Stereoscopic endoscope

[0002] This is a divisional of application Ser. No. 08/564,537, filed Nov. 29, 1995, the contents of which are herein incorporated by reference in its entirety.

[0003] The present invention relates to a stereoscopic endoscope which allows an observer to view a three-dimensional image of an object under test.

[0004] A stereoscopic endoscope is used to observe an object or cavity internal to a machine or the human body. Examples of rigid type stereoscopic endoscopes are disclosed in, for example, U.S. Pat. No. 4,364,629 and Japanese Laid Open Publication Hei. 6-194581. In these examples, the stereoscopic endoscopes have an insertion portion which includes an objective lens for forming an image of the object and a relay lens for transmitting the light to an exit pupil of the insertion portion. The stereoscopic endoscopes also include an observing -portion, which includes an-optical device for splitting the light at the exit pupil and directing the split light beams to a left and right optical imaging system, through which an observer-would view a three-dimensional image of the object.

[0005] However, if the optical device for splitting the light beam is not positioned correctly, the three-dimensional effect of the image may be reduced, thereby reducing the effectiveness of the endoscope. Further, even if the optical device for splitting the light beam is positioned correctly for an object located near to the insertion portion of the endoscope, the three-dimensional effect of an image of an object located far away from the insertion point of the endoscope may be reduced. This also reduces the effectiveness of the endoscope.

[0006] In conventional stereoscopic endoscopes, the three-dimensional image is viewed directly, using eyepiece lenses, or indirectly using an imaging device such as a CCD, and a video processor. Use of an imaging device allows the images to be viewed by many people, through the use of a monitor and special viewing glasses. However, this requires extra hardware and elaborate image processing. In a direct viewing endoscope, the image may be viewed easily and quickly through the eyepiece lenses, but by only one person at a time. Thus, extra time will be required if many people are to view the image.

[0007] Further, in a conventional stereoscopic endoscope that employs the imaging devices, one imaging device is used with each optical system, thereby increasing the cost of manufacturing the cost of the endosocope.

[0008] In conventional stereoscopic endoscopes the optical device for splitting the light beam uses a series of reflective surfaces in order to properly split the light beam. Therefore, the positional relationship between the various reflective surfaces must be set precisely. Further, in order properly position all of the reflective surfaces, the size of the endoscope must be made large, thereby reducing the effectiveness of the endoscope. Furthermore, the number of parts required to manufacture the endoscope is increased.

[0009] In a conventional stereoscopic endoscope, light is provided to illuminate the object by using a separate light source and an optical guide. The optical guide is housed in the insertion portion of the stereoscopic endoscope, and is parallel to the optical axis of optical system used for viewing the image. This results in the diameter of the insertion portion being large, and therefore the insertion portion cannot be as easily inserted into the cavity.

[0010] It is therefore an object of the present invention to provide an improved stereoscopic endoscope in which the position of a device for splitting the light beam, can be positioned at the standard correct position quickly and accurately.

[0011] It is another object of the present invention to provide an improved stereoscopic endoscope in which the three-dimensional effect of the image viewed using the endosocope can be changed quickly and easily.

[0012] It is a further object of the present invention to improve the utility of a stereoscopic endoscope in which the image of the object can be viewed by many people or by a single person, quickly.

[0013] It is yet a further object of the present invention to provide an improved stereoscopic endoscope in which a single imaging device is used, thereby reducing the size of the endoscope and the number of parts required to manufacture the endosocope.

[0014] It is still another object of the present invention to provide an adapter for use with a stereoscopic endoscope which allows a wide range of insertion portions of monocular endoscopes to be used with an observing portion of the stereoscopic endoscope.

[0015] It is still a further object of the present invention to provide an improved stereoscopic endoscope which can illuminate the object to be viewed without increasing the diameter of the insertion portion of the stereoscopic endoscope.

[0016] According to a first aspect of the present invention, there is provided a stereoscopic endoscope which includes: a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system; a device for dividing the light transmitted to the second end of the primary optical system into two light beams, and a pair of secondary optical systems. Each of the secondary optical systems has an imaging device which outputs an image signal. Each of the secondary optical systems receives one of the light beams and forms an image of the object on its corresponding imaging device. The stereoscopic endoscope also includes a device for adjusting a position of the light dividing device relative to an optical axis and exit pupil of the primary optical system, and a device for detecting a position of the light dividing device in accordance with each of the output image signals.

[0017] In a preferred embodiment, the detecting device detects the position of the light dividing device in accordance with a distribution of a brightness of each image formed on each of the imaging devices, by an object having uniform brightness. Further, the stereoscopic endoscope calculates an amount and direction of movement required to move the adjusting device to a standard correct position, in accordance with the distribution of brightness of the images formed on each of the imaging devices. Therefore, the stereoscopic endoscope can automatically position the light dividing device at the standard correct position, quickly and accurately. This ensures that an image having the proper three-dimensional effect can be observed by the user.

[0018] Still preferably, the stereoscopic endoscope also includes a device for processing the image signals to produce left and right images, and a device for calculating the amount and direction of movement required to position the light dividing device at the standard correct position.

[0019] In a preferred embodiment, the processing device and the calculating device are located in a common housing, which is separate from the housing of the stereoscopic endoscope.

[0020] In another preferred embodiment, the processing device and the calculating device are located in separate housings. Therefore, during normal use of the stereoscopic endoscope, only the processing device needs to be attached to the stereoscopic endoscope, thereby reducing the size of the stereoscopic endoscope system.

[0021] In yet another preferred embodiment, the calculating device is provided inside the stereoscopic endoscope housing, and the processing means is provided in a separate housing. This reduces the overall size required for the stereoscopic endoscope system.

[0022] Optionally, the primary optical system is provided by a monocular endoscope, which is attached to an adapter. The adapter is then attached to an observing portion of the stereoscopic endoscope which includes the light dividing device and the pair of secondary optical systems. This permits automatic positioning of the light dividing device relative to an exit pupil of any monocular endoscope.

[0023] The position of the adapter relative to the light dividing device may be adjusted by varying a position of adjustment screws used to secure the adapter to the observing portion. Furthermore, by including motors, the adjustment of the position of the screws can be done automatically.

[0024] In another preferred embodiment, the stereoscopic endoscope includes an indicator for indicating the calculated amount and direction of movement required to position the light dividing device at the standard correct position. The adjustment of the position of the light dividing device can then be done manually using the indicated information.

[0025] In yet another preferred embodiment, a single imaging device replaces the imaging device used in each of the secondary systems. This reduces the overall cost of manufacturing the stereoscopic endoscope.

[0026] In order to further reduce the cost of manufacture, the size of the imaging device can be reduced, and the formation of the images by the two secondary optical systems on the imaging device are alternated.

[0027] The viewing of the three-dimensional image of the object may be achieved by using a monitor to alternately display the left and right images, and special glasses to alternately transmit the left and right images to the corresponding eye of the observer.

[0028] In a preferred embodiment, the light dividing device is a mirror block having two reflective surfaces which are perpendicular to each other, and arranged at a 45° angle to an optical axis of the primary optical system. Further, the adjusting device may include:

[0029] a frame for holding the mirror block;

[0030] a first screw fitted into the holding frame;

[0031] a first gear which meshes with the first screw, the first gear rotating about an axis;

[0032] a second screw fitted into a mounting member attached to the observing portion and having a nut through which the first screw is threaded; and

[0033] a second gear which meshes with the second screw, the first gear rotating about another axis.

[0034] The holding frame is moved in a first plane in response to a rotation of the first gear, and is moved in a second plane in response to a rotation of the second gear, with the first plane being perpendicular to the second plane.

[0035] In an alternative embodiment, the mirror block is replaced with a pair of mirrors attached to separate supports. The pair of mirrors are arranged in a similar position relative to the primary optical axis, as the reflective surfaces of the mirror block. This reduces the need for a mirror block and results in reduction in the weight of the stereoscopic endoscope.

[0036] According to a second aspect of the present invention, there is provided a stereoscopic endoscope having an optical system for transmitting a luminous flux, reflected by an object located near a first end of the optical system, to a second of the optical system. The stereoscopic endoscope forms a first image of the object in accordance with a first area of the luminous flux, and forms a second image of the object in accordance with a second area of the luminous flux. The second area of the luminous flux does not overlap the first area of the luminous flux. The stereoscopic endoscope also includes a device for adjusting a distance between an optical axis of the first area of the luminous flux and an optical axis of the second area of the luminous flux, such that a size of the first area of the luminous flux remains equal to a size of the second area of the luminous flux.

[0037] In a preferred embodiment, the stereoscopic endoscope includes a device for guiding the first area of the luminous flux to a first device for forming a first image, and a device for guiding the second area of the luminous flux to a second device for forming the second image

[0038] Preferably, the adjusting device includes a screw and a gear which rotates about an axis and meshes with a center of the screw. The two guiding devices are attached to separate supports, with one support threaded onto the screw on one side of the center of the screw, and the other support threaded onto the screw on the other side of the center of the screw. By rotating the gear, the supports move towards or away from each other along an axis of the screw.

[0039] Therefore, the distance between the central axis of the two portions of the luminous flux which form the first and second images, can be adjusted. Thus, the three-dimensional effect of the observed image can be adjusted, by rotating the gear.

[0040] In a preferred embodiment the guiding devices are mirrored surfaces for reflecting the first area of the luminous flux to the first image forming device, and for reflecting the second area of the luminous flux to the second image forming device.

[0041] In another preferred embodiment, each of the first and second image forming devices includes an imaging lens for forming the respective image and an eyepiece lens for viewing the image.

[0042] In yet another preferred embodiment, each of the first and second image forming devices includes an imaging lens for forming the respective image and an imaging device for detecting the image and for outputting an image signal. The imaging device can include a CCD.

[0043] Optionally, each of the secondary optical systems may also have an eyepiece lens to allow simultaneous direct viewing of the image, and indirect viewing using the imaging devices.

[0044] Further optionally, the primary optical system is provided by an insertion portion of a monocular endoscope which is attached using an adapter to an observing portion of the stereoscopic endoscope. Therefore, the range of endoscopes which may be used with the apparatus having the present invention is increased.

[0045] Alternatively, each guiding device and corresponding image forming device is replaced with a separator lens and an imaging device. Each separator lens receives one of the respective portions of the luminous flux and forms an image, which is detected by the corresponding imaging device. The imaging devices output image signals, which can be processed to produce a three-dimensional image. Therefore, in this case, the adjusting device changes the distance between the optical axes of the separator lenses.

[0046] Optionally, an optical fiber bundle may be used to transfer the luminous flux from the separator lens to the corresponding imaging device. This increases the flexibility of positioning the imaging devices.

[0047] Alternatively, the imaging device is replaced with an imaging lens and an eyepiece lens for direct viewing of the three-dimensional image by an observer.

[0048] In another alternative embodiment, the stereoscopic endoscope has a single imaging device and each of separator lenses forms one of the images on the single imaging device. By employing one imaging device, the cost of manufacturing the stereoscopic endoscope can be decreased.

[0049] According to a third aspect of the present invention, there is provided a stereoscopic endoscope which includes: a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system; a plurality of secondary optical systems, each of the secondary optical systems receiving a separate portion of the light and forming an image of the object; and a plurality of devices for guiding a separate portion of the light transmitted to the second end of the primary optical system, to each of the secondary optical systems. The stereoscopic endoscope also includes a device for selecting a predetermined number of the images for viewing the object. Therefore, by selecting images which are formed by secondary optical systems which are closer together or further apart, the three-dimensional effect of the observed image can be varied.

[0050] In a preferred embodiment, each of the plurality of guiding devices and corresponding plurality of secondary optical systems is replaced with a separator lens, and an imaging device. Each separator receives one of the portions of transmitted light and forms an image of the object on the corresponding imaging device. The imaging devices output image signals corresponding to the images formed by the separator lenses.

[0051] In another preferred embodiment, each of the guiding devices includes a separator lens for receiving the separate portions of the light. Further, each of the secondary optical systems includes an imaging lens, an imaging device, and an optical fiber bundle for guiding the received portions of the light from the separator lens to the imaging lens. The imaging lens forms an image on the imaging device, which outputs the image signal.

[0052] Alternatively, some of the imaging devices are replaced with eyepiece lenses to allow direct viewing of the three-dimensional image of the object. Therefore, simultaneous direct viewing using the eyepiece lenses and indirect viewing using the imaging devices is possible. optionally, some of the secondary optical systems are provided with an eyepiece lens, a half mirror and an imaging device. This also allows direct viewing with the eyepiece lens as well as more choices for indirectly viewing the image using the imaging devices.

[0053] Preferably, at least three secondary optical systems, and three guiding devices are provided.

[0054] In another preferred embodiment, one imaging device is provided and two secondary optical systems are provided to form two images on two areas of the single imaging device. optionally, each of the secondary optical systems is provided with a liquid crystal shutter, which allows or prohibits the formation of the image by the secondary optical system. Therefore, when the image is being formed by one of the secondary optical systems on the single imaging device, the liquid crystal shutter of the other secondary optical system prohibits the formation of the other image by the other secondary optical system.

[0055] In this case, the first area and second area of the single imaging device can overlap, and therefore, the size of the single imaging device can be reduced, thereby reducing the cost of manufacturing the stereoscopic endoscope.

[0056] According to a fourth aspect of the present invention, there is provided a stereoscopic endoscope which includes: a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system. The prism for dividing the light transmitted to the second end of the primary optical system into two light beams, with the two light beams not being parallel to each other; and a pair of secondary optical systems which receive one of the light beams and forming an image of the object. Therefore, the size of the stereoscopic endoscope can be reduced since extra space is not required to have parallel secondary optical systems.

[0057] In a preferred embodiment, the primary optical system is housed within an insertion portion of the stereoscopic endoscope, and the secondary optical systems are housed within an observing portion of the endoscope. The insertion portion is attached to the observing portion using a cylindrical adapter. This allows the insertion portion of monocular endoscopes to be used with the observing portion of the stereoscopic endoscope.

[0058] In another preferred embodiment, each of the secondary optical systems includes an imaging lens for forming an image of the object in accordance with the refracted light beam, and an imaging device for detecting the images formed by the imaging lens, with the imaging devices outputting image signals.

[0059] Alternatively, the stereoscopic endoscope is provided with a single imaging device. The images formed by the imaging lenses of the secondary optical systems is formed on different areas of the single imaging device.

[0060] Optionally, each of the secondary optical systems is provided with a liquid crystal shutter, which allows or prohibits the formation of the image by the secondary optical system. Therefore, when the image is being formed by one of the secondary optical systems on the single imaging device, the liquid crystal shutter of the other secondary optical system prohibits the formation of the other image by the other secondary optical system

[0061] In this case, the first area and second area of the single imaging device can overlap, and therefore, the size of the single imaging device can be reduced, thereby reducing the cost of manufacturing the stereoscopic endoscope.

[0062] In yet another preferred embodiment, each of the secondary optical systems includes a prism for refracting the received light beams, such that the refracted light beams are parallel to an optical axis of the primary optical system, an imaging lens for forming an image of the object in accordance with the refracted light beam, and an eyepiece lens for viewing the image formed by the imaging lens. This permits direct viewing of the three-dimensional image.

[0063] Alternatively, a single deflecting prism is provided for refracting the received light beams. This reduces the number of parts required to manufacture the stereoscopic endoscope.

[0064] Further, a single roof prism may replace the prism used for dividing the light. This results in a less complex prism being used in the manufacturing of the stereoscopic endoscope.

[0065] According to a fifth aspect of the present invention, there is provided a method of adjusting a position of a light dividing mechanism of a stereoscopic endoscope to a predetermined position. Light from an object having a uniform brightness is transmitted by a primary optical system of the stereoscopic endoscope to the light dividing mechanism, which divides the light into two light beams, with each light-beam being incident on an imaging device. The method includes the steps of:

[0066] detecting a brightness pattern of an image formed on each of the imaging devices;

[0067] determining a direction and amount of movement required to position the light dividing mechanism at the predetermined position, in response to the detected brightness pattern of each of the images; and

[0068] adjusting the position of the light dividing mechanism in accordance with the direction and movement amount determined in the determining step.

[0069] In a preferred embodiment, the determining step includes the steps of calculating a direction of movement of the light dividing mechanism, and comparing a position of the light dividing mechanism with the predetermined position. Further, the adjusting step includes the step of driving the light dividing mechanism by a fixed amount. Furthermore, the detecting step, the determining step and the adjusting step are repeated until the determining step determines that the position of the light dividing mechanism is at the predetermined position. Since the calculating step only determines a direction of movement, the number of bits required for the calculation is low.

[0070] Alternatively, the calculating step also calculates the amount of movement required to move the light dividing mechanism to the predetermined position In this case, the driving step drives the light dividing mechanism directly to the predetermined position, after the first calculation. Therefore, the light dividing mechanism can be quickly and accurately placed at the predetermined position.

[0071] According to a sixth aspect of the present invention, there is provided an adapter for enabling a monocular endoscope to be used with a stereoscopic observing portion. The observing portion includes a device for dividing light transmitted by the monocular endoscope, into two light beams, by a pair of optical systems. Each of the optical systems receives one of the light beams and forms an image of the object. The adapter includes a device for connecting the observing portion of the stereoscopic endoscope to the monocular endoscope.

[0072] Thus, the range of insertion portions that can be used with the observing portion of the stereoscopic endoscope is increased.

[0073] In a preferred embodiment, the connecting device includes a plurality of screws and nuts for attaching the adapter to the observing portion. Therefore, the adapter can be easily attached to the observing portion of the stereoscopic endoscope.

[0074] In another preferred embodiment, the connecting device includes a device for adjusting a positional relationship of the observing portion and the monocular endoscope. This allows for accurate positioning of the monocular endoscope in relation to the light dividing device of the observing portion. Therefore, the three-dimensional effect of the image can be changed by using the adjusting device.

[0075] In the preferred embodiment, the adjusting device includes a first set of screws oriented along a first direction, and a second set of screws oriented along a second direction. The second direction may be perpendicular to the first direction. Further, the first set of screws adjusts a position of the adapter relative to the observing portion along the first direction. The second set of screws adjusts a position of the adapter relative to the observing portion along the second direction. Therefore, accurate two dimensional adjustment of the position of the monocular endoscope relative to the observing portion can be achieved.

[0076] Optionally, each screw is rotated by a motor. This allows automatic adjustment of the position of the monocular endoscope relative to the observing portion.

[0077] According to a seventh aspect of the present invention, there is provided a stereoscopic endoscope which has a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, along a first optical path to an exit pupil located at a second end of the primary optical system. The stereoscopic endoscope is also provided with a device for dividing the light transmitted to the second end of the primary optical system into two light beams, and a pair of secondary optical systems. Each of the secondary optical systems receives one of the light beams and forms an image of the object. The stereoscopic endoscope further provides a device for emitting light through a second optical path of the primary optical system which is parallel to the first optical path. The emitted light is incident on the object and does not interfere with the first optical path. Therefore, the stereoscopic endoscope provides the light required for viewing the object, and an auxiliary light source is not need.

[0078] According to an eighth aspect of the present invention, there is provided a stereoscopic endoscope having a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system. The stereoscopic endoscope also includes a device for dividing the light transmitted through the primary optical system into two light beams, and a pair of secondary optical systems. Each of the secondary optical systems receives one of the light beams and forms an image of the object. Further, each of the secondary optical systems includes an eyepiece lens for viewing the image and an imaging device for detecting the images formed by the secondary optical system. A half mirror is provided in each secondary optical system for reflecting half of the received light to one of the eyepiece lens and the imaging device, and for transmitting the other half of the received light to other of the-eyepiece lens and the imaging device.

[0079] Therefore, the three-dimensional image can be viewed directly using the eyepiece lenses or indirectly using the imaging devices. This increases the facility of the viewing of the three-dimensional image observed using the stereoscopic endoscope.

[0080] In a preferred embodiment, the light dividing device includes two mirrors arranged perpendicular to each other, with each of the mirrors arranged at a 45 angle to an optical axis of the primary optical system. Further, stereoscopic endoscope also includes a device for adjusting a distance between each of the two mirrors. Therefore, by adjusting the distance between the two mirrors, the three-dimensional effect of the image can be changed.

[0081] In another preferred embodiment, the dividing device includes a half mirror for dividing the light into the two light beams. This reduces the number of parts required to manufacture the endoscope.

[0082] According to a ninth aspect of the present invention, there is provided a stereoscopic endoscope having a primary optical system for transmitting a luminous flux, reflected by an object located near a first end of the optical system, to a second end of the optical system. The stereoscopic endoscope also includes a device for forming a first image of the object in accordance with a first area of the luminous flux, and another device for forming a second image of the object in accordance with a second area of the luminous flux. The second area of the luminous flux does not overlap the first area of the luminous flux. A single imaging device detects the first image and the second image and outputs an image signal. By using only one imaging device, the cost of manufacturing the stereoscopic endoscope can be decreased.

[0083] In a preferred embodiment, the first image is formed on a first portion of the imaging device, and the second image is formed on a second portion of the imaging device, which is separate from the first portion. Therefore, by processing the image signal, the left and right images can be obtained.

[0084] In another preferred embodiment, each image forming device is provided with a liquid crystal shutter, which controls a timing of the image formation by alternately prohibiting and allowing transmission of light through the image forming device. Further, the first and second images are alternately formed on overlapping portions of the imaging device. Therefore, the size of the imaging device can be reduced, and the cost of manufacturing the stereoscopic endoscope can also be reduced.

[0085] FIG. 1A shows a sectional view of a stereoscopic endoscope according to a first embodiment of the present invention.

[0086] FIG. 1B shows a block diagram of a processing device used with the stereoscopic endoscope shown in FIG. 1A, according to the first embodiment of the present invention;

[0087] FIGS. 2A and 2B are enlarged views of a mirror block of the stereoscopic endoscope shown in FIG. 1;

[0088] FIGS. 3A and 3B are perspective views for defining directions of movement of the mirror block shown in FIG. 2A;

[0089] FIG. 4 is a top view of the mirror block showing optical paths when the mirror block is positioned at a standard correct position;

[0090] FIG. 5A is a top view of the mirror block showing optical paths when the mirror block is linearly displaced in a +x direction from the standard correct position;

[0091] FIG. 5B shows a brightness distribution of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is in the position shown in FIG. 5A;

[0092] FIG. 6A is a top view of the mirror block showing optical paths when the mirror block is linearly displaced in a −x direction from the standard correct position;

[0093] FIG. 6B shows a brightness distribution of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is in the position shown in FIG. 6A;

[0094] FIG. 7A is a top view of the mirror block showing optical paths when the mirror block is linearly displaced in a +y direction from the standard correct position;

[0095] FIG. 7B shows a brightness distribution of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is in the position shown in FIG. 7A;

[0096] FIG. 8A is a front view of the mirror block from the object side showing optical paths when the mirror block is rotated about the x-axis from the standard correct position;

[0097] FIG. 8B shows a brightness distribution of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror-block is in the position shown in FIG. 8A;

[0098] FIG. 9A is a front view of the mirror block from the object side showing optical paths when the mirror block is rotated about the y-axis from the standard correct position;

[0099] FIG. 9B shows a brightness distribution of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is in the position shown in FIG. 9A;

[0100] FIG. 10A is a top view of the mirror block showing optical paths when the mirror block is rotated about the z-axis from the standard correct position;

[0101] FIG. 10B shows a brightness distribution of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is in the position shown in FIG. 10A;

[0102] FIGS. 11A and 11B show brightnesses of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is moved in along the x-axis in the +x and −x directions, respectively;

[0103] FIGS. 11C and 11D show brightnesses of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is moved in along the y-axis in the +y and −y directions, respectively;

[0104] FIGS. 11E and 11F show brightnesses of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is rotated about the x-axis in the clockwise and counterclockwise directions, respectively;

[0105] FIGS. 11G and 11H show brightnesses of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is rotated about the y-axis in the clockwise and counterclockwise directions, respectively;

[0106] FIGS. 11I and 11J show brightnesses of left and right images taken by the stereoscopic endoscope shown in FIG. 1, when the mirror block is rotated about the z-axis in the clockwise and counterclockwise directions, respectively;

[0107] FIGS. 12A through 12D are flowcharts showing four different methods for adjusting the position of the mirror block according to the first embodiment of the present invention;

[0108] FIG. 13 shows a block diagram of a processing device used with the stereoscopic endoscope shown in FIG. 1A according to a second embodiment of the present invention;

[0109] FIG. 14 shows a sectional view of a stereoscopic endoscope and block diagram of the stereoscopic endoscope, according to third embodiment of the present invention;

[0110] FIG. 15A shows a sectional view of a stereoscopic endoscope according to fourth embodiment of the present invention;

[0111] FIG. 15B shows a block diagram of the processing device used with the stereoscopic endoscope shown in FIG. 15A according to the fourth embodiment of the present invention;

[0112] FIG. 16 shows a sectional view of an observing portion of a stereoscopic endoscope according to a fifth embodiment of the present invention;

[0113] FIG. 17 shows a sectional view of an observing portion of a stereoscopic endoscope according to a sixth embodiment of the present invention;

[0114] FIGS. 18A and 18B are enlarged views of a mirror block shown in FIG. 17;

[0115] FIG. 19 shows a sectional view of an observing portion of a stereoscopic endoscope according to a seventh embodiment of the present invention;

[0116] FIG. 20 shows a sectional view of an observing portion of a stereoscopic endoscope according to an eighth embodiment of the present invention;

[0117] FIG. 21A shows a sectional view of a stereoscopic endoscope according to a ninth embodiment of the present invention;

[0118] FIG. 21B shows a block diagram of a processing device used with the stereoscopic endoscope shown in FIG. 21A according to the ninth embodiment of the present invention;

[0119] FIG. 22A shows a sectional view of a stereoscopic endoscope according to a tenth embodiment of the present invention;

[0120] FIG. 22B shows a block diagram of a processing device used with the stereoscopic endoscope shown in FIG. 22A according to the tenth embodiment of the present invention;

[0121] FIG. 23 shows a sectional view of a stereoscopic endoscope of a eleventh embodiment of the present invention;

[0122] FIG. 24 is a front view of a mirror block viewed from an object side, showing a relationship between an illumination light beam and an observing field of an exit pupil of a primary optical system of the stereoscopic endoscope shown in FIG. 23;

[0123] FIG. 25 is a sectional view of a stereoscopic endoscope according to a twelfth embodiment of the present invention;

[0124] FIG. 26A is an enlarged top view of a pupil dividing mechanism of the stereoscopic endoscope shown in FIG. 25;

[0125] FIG. 26B is an enlarged side view of the pupil dividing mechanism of the stereoscopic endoscope shown in FIG. 25;

[0126] FIG. 27A is a top view of mirrors of the pupil dividing mechanism showing light paths when the mirrors are positioned closest to each other;

[0127] FIG. 27B is a front view of the mirrors shown in FIG. 27A viewed from an object side;

[0128] FIG. 28A is a top view of the mirrors of the pupil dividing mechanism showing light paths when the mirrors are positioned furthest apart;

[0129] FIG. 28B is a front view from an object side under the condition shown in FIG. 28A;

[0130] FIG. 29 is a sectional view of an observing portion of a thirteenth embodiment according to the present invention;

[0131] FIG. 30 is a sectional view of a stereoscopic endoscope according to a fourteenth embodiment of the present invention;

[0132] FIG. 31 is a sectional view of a stereoscopic endoscope according to a fifteenth embodiment of the present invention;

[0133] FIG. 32 is a sectional view of a stereoscopic endoscope according to a sixteenth embodiment of the present invention;

[0134] FIG. 33 is a sectional view of a stereoscopic endoscope according to a seventeenth embodiment of the present invention;

[0135] FIG. 34 is a sectional view of a stereoscopic endoscope according to an eighteenth embodiment of the present invention;

[0136] FIG. 35 is a sectional view of a stereoscopic endoscope according to a nineteenth embodiment of the present invention;

[0137] FIG. 36 is a sectional view of a stereoscopic endoscope according to a twentieth embodiment of the present invention;

[0138] FIG. 37 is a sectional view of a stereoscopic endoscope according to a twenty-first embodiment of the present invention;

[0139] FIG. 38A is a top view of separator lenses of a pupil dividing mechanism of the twenty-first embodiment showing light paths when the separator lenses are positioned closest to each other;

[0140] FIG. 38B is a top view of the separator lenses of the pupil dividing mechanism of the twenty-first embodiment showing light paths when the separator lenses are positioned farthest apart;

[0141] FIG. 39A is a top view of the separator lenses of the pupil dividing mechanism according to a modification of the twenty-first embodiment, showing light paths when the separator lenses are positioned closest to each other;

[0142] FIG. 39B is a top view of the separator lenses of the pupil dividing mechanism according to a modification of the twenty-first embodiment;

[0143] FIG. 40A is a top view of a shading plate used in the pupil dividing mechanism according to the modification of the twenty-first embodiment;

[0144] FIGS. 40B is a top view of a modification of the shading plate used in the pupil dividing mechanism according to the modification of the twenty-first embodiment;

[0145] FIG. 41 is a sectional view of a stereoscopic endoscope according to a twenty-second embodiment of the present invention;

[0146] FIG. 42A is a top view of separator lenses of a pupil dividing mechanism according to a twenty-third embodiment of the present invention, showing light paths when the separator lenses are positioned closest to each other;

[0147] FIG. 42B is a front view of the separator lenses of the pupil dividing mechanism, viewed from the object side, showing a relationship between illumination light beams and an observing field of an exit pupil of the primary optical system of the stereoscopic endoscope;

[0148] FIG. 43 is a sectional view of a stereoscopic endoscope according to a twenty-fourth embodiment of the present invention;

[0149] FIG. 44 is a sectional view of a stereoscopic endoscope according to a twenty-fifth embodiment of the present invention;

[0150] FIG. 45 is a sectional view of a stereoscopic endoscope according to a twenty-sixth embodiment of the present invention;

[0151] FIG. 46 is a sectional view of a stereoscopic endoscope according to a twenty-seventh embodiment of the present invention;

[0152] FIG. 47 is a sectional view of a stereoscopic endoscope according to a twenty-eighth embodiment of the present invention;

[0153] FIG. 48 is a sectional view of an observing portion of a stereoscopic endoscope-according to a twenty-ninth embodiment of the present invention;

[0154] FIG. 49 is a sectional view of a stereoscopic endoscope according to a thirtieth embodiment of the present invention;

[0155] FIG. 50A is a sectional view of a stereoscopic endoscope according to a thirty-first embodiment of the present invention;

[0156] FIG. 50B is an enlarged view of a pupil dividing mechanism of an observing unit of the stereoscopic endoscope shown in FIG. 50A;

[0157] FIG. 50C shows a front view of an arrangement of separator lenses of the pupil dividing mechanism shown in FIG. 50B, with respect to an exit pupil of a primary optical system of the stereoscopic endoscope shown in FIG. 50A;

[0158] FIG. 51 shows a block diagram of an apparatus that uses a lenticular screen to display three-dimensional images of images viewed using a stereoscopic endoscope;

[0159] FIG. 52 shows a sectional view of an observing portion of a stereoscopic endoscope according to a thirty-second embodiment of the present invention;

[0160] FIG. 53 shows a sectional view of a stereoscopic endoscope according to a thirty-third embodiment of the present invention;

[0161] FIG. 54 shows a sectional view of a stereoscopic endoscope according to a thirty-fourth embodiment of the present invention;

[0162] FIG. 55 shows a sectional view of a stereoscopic endoscope according to a thirty-fifth embodiment of the present invention;

[0163] FIG. 56A shows a sectional view of a stereoscopic endoscope according to a thirty-sixth embodiment of the present invention;

[0164] FIG. 56B is an enlarged view of an observing portion of the stereoscopic endoscope shown in FIG. 56A;

[0165] FIG. 57 is a sectional view of a stereoscopic endoscope according to a thirty-seventh embodiment of the present invention;

[0166] FIGS. 58A through 58D are front views showing modified arrangements of separator lenses in an exit pupil of a primary optical system of the stereoscopic endosocope shown in FIG. 56A;

[0167] FIGS. 59A through 59D are front views showing additional modified arrangements of the separator lenses shown in FIGS. 58A through 58D;

[0168] FIG. 60 is a sectional view of a stereoscopic endoscope according to a thirty-eighth embodiment of the present invention;

[0169] FIG. 61 is a sectional view of an observing portion of a stereoscopic endoscope according to a thirty-ninth embodiment of the present invention;

[0170] FIG. 62 is a sectional view of a stereoscopic endoscope according to a fortieth embodiment of the present invention;

[0171] FIG. 63 is an enlarged view of an observing portion of the stereoscopic endoscope shown in FIG. 62;

[0172] FIG. 64 is a sectional view of a stereoscopic endoscope according to a forty-first embodiment of the present invention;

[0173] FIG. 65 is a sectional view of an observing portion of stereoscopic endoscope according to a forty-second embodiment of the present invention;

[0174] FIG. 66 shows a sectional view of a stereoscopic endoscope according to a forty-third embodiment of the present invention;

[0175] FIG. 67 shows a sectional view of a stereoscopic endoscope according to a forty-fourth embodiment of the present invention;

[0176] FIG. 68 is an enlarged view of an observing portion of a stereoscopic endoscope according to a forty-fifth embodiment of the present invention;

[0177] FIG. 69 is an enlarged view of an observing portion of a stereoscopic endoscope according to a forty-sixth embodiment of the present invention; and

[0178] FIG. 70 is a sectional view of a stereoscopic endoscope according to a forty-seventh embodiment of the present invention.

[0179] The present invention will now be described with reference to FIGS. 1A through 70.

[0180] FIG. 1A shows a sectional view of a stereoscopic endoscope according to the present invention. The stereoscopic endoscope comprises an insertion portion 1 and an observing portion 2. The insertion portion 1, is inserted through a narrow opening into an object or cavity (such as the digestive tract or abdominal cavity of the human body) that is to be observed. The observing portion 2 is optically connected to the insertion portion 1 and allows an observer to see an image of the object being observed.

[0181] The insertion portion 1 includes a primary optical system 10. The primary optical system 10, as shown in FIG. 1A, consists of an objective lens 11, a first relay lens 12, and a second relay lens 13 In this specification the term “lens” can mean a “single lens” or “group of lenses”. The objective lens 11 forms an image of the object being observed. The first relay lens 12 and second relay lens 13 transmit the image to an exit pupil of the optical system 10, in order to be observed by the observing portion 2.

[0182] The observing portion 2 includes a pupil dividing mirror block 20, and a pair of secondary optical systems 30A and 30B. The mirror block 20 consists of a pair of mirrored surfaces 20aand 20b(see, e.g., FIGS. 1A and 1B). The optical systems 30A, 30B consist of mirrors 31a,31b,imaging lenses 32a,32band imaging devices 34a,34b,respectively. In the preferred embodiment, the imaging devices 34a,and 34bare CCDs.

[0183] Light from the primary optical system 10 that is incident on the mirrored surface 20ais reflected to the mirror 31aand then reflected to the imaging lens 32a.The imaging lens 32aforms an image on the imaging device 34a.Similarly, light from the primary optical system 10 that is incident on the mirrored surface 20bis reflected to the mirror 31band then reflected to the imaging lens 32b.The imaging lens 32bforms an image on the imaging device 34b.

[0184] As shown in FIG. 1A, and described above, the light transmitted from the primary optical system 10, is divided into two separate paths and an image of the divided light is produced by the secondary optical systems 30aand 30b.The secondary optical system 30aforms an image that is seen by a right eye of the observer, while the secondary optical system 30bforms an image that is seen by a left eye of the observer. Therefore, each of the optical systems 30a,30bwill produce an image of the object from a slightly different perspective, resulting in a three-dimensional view of the object being observed.

[0185] However, in order to achieve the proper three-dimensional perspective of the object, an area of the exit pupil through which light is transferred to the secondary optical system 30a,must be the same size as an area of the exit pupil through which light is transferred to the secondary optical system 30b.

[0186] FIG. 2A shows an enlargement of the mirror block 20, the secondary optical systems 30a,30b,and the exit pupil of the primary optical system 10. In order to achieve the proper three-dimensional perspective, the ridge line between the mirrored surfaces 20aand 20b,must be coincident with the plane of the exit pupil Ep and an optical axis Ax1 of the primary optical system 10. If this condition is satisfied, then the mirror block 20 is in the standard correct position. Further, the mirrored surfaces 20a,20bare arranged to be at an angle of 45° to the optical axis Ax1, when the mirror block 20 is at the standard correct position.

[0187] Further, as shown in FIG. 2A, when the mirror block 20 is at the standard correct position, a center axis Ax2 of the light reflected by the mirrored surface 20ais coincident with an optical axis of the secondary optical system 30a,and a center axis Ax3 of the light reflected by the mirrored surface 20bis coincident with an optical axis of the secondary optical system 30b.Further, the axes Ax2 and Ax3 are positioned at a predetermined distance on either side of the axis Ax1, and therefore, parallax corresponding to the distance occurs in the images formed at the imaging devices 34A and 34B.

[0188] FIGS. 3 through 10 will be used to explain the effect on the image detected by the imaging devices 34aand 34b,by moving the mirror block 20 from the standard correct position As shown in FIGS. 3A through 10B, the uniformity of brightness of the two images will be affected by the movement of the-mirror block 20. Further, the exit pupil Ep is shown as a bold line in FIGS. 4 through 10A.

[0189] The mirror block 20 has six degrees of freedom, as shown in FIGS. 3A and 3B. The mirror block 20 can be moved along the x-axis, y-axis or z-axis. Further, the mirror block 20 may be rotated about any of these axes. However, movement along the z-axis may be ignored, since the mirror block 20 has enough height in the z-axis direction. Hereinafter, only five degrees of freedom will be described.

[0190] In the following description, φ1 denotes the movement along the x-axis, φ2 the movement along the y-axis, φ3 the rotation about the x-axis, φ4 the rotation about the y-axis and φ5 the rotation about the z-axis.

[0191] FIG. 3A shows the reference x, y and z axes. Movement along one of the axes in a direction toward the arrow is defined as positive (+) movement, while the movement in the reverse direction is defined as negative (−) movement. FIG. 3B shows one of the three axes and a rotation movement about the axis. Clockwise rotation about the axis is defined as positive (+) rotation, while counterclockwise rotation is defined as negative (−) rotation.

[0192] FIG. 4 shows the light paths incident from the second relay lens 13 and divided by the mirror block 20 that is located at the standard correct position (i.e., all displacements in any direction are equal to zero). At this position, the center light beam (shown by solid line L0) transmitted along the optical axis Ax1, the left light beam (shown by line LL) transmitted from the left side of the primary optical system 10, and the right light beam (shown by line LR) transmitted from the right side of the primary optical system 10, are each divided into two uniformly equal light beams by the mirror block 20.

[0193] FIG. 5A shows the mirror block 20 displaced from the standard correct position by +φ1, (i.e., in the positive x-axis direction). In this case, the fraction of the left light beam LL that is incident on the right mirror surface 20ais increased, and the fraction of the right light beam LR that is incident on the left mirror surface 20bis also increased. The center light beam L0 remains divided into two equal light beams.

[0194] FIG. 5B shows the effect on the right and left images detected by the CCDs 34A and 34B, respectively, when the mirror block 20 is moved from the standard correct position by +φ1. As shown in FIG. 5B, the left side of the left image, and the right side of the right image become dark. The remaining portions of the two images become bright.

[0195] FIG. 6A shows the pupil dividing mirror block 20 displaced from the standard correct position by φ1 (i.e., in the negative x-axis direction). In this case, the fraction of the left light beam LL that is incident on the left mirror surface 20bis increased, and the fraction of the right light beam LR that is incident on the right mirror surface 20ais also increased. The center light beam L0 remains equally divided.

[0196] FIG. 6B shows the effect on the right and left images detected by the CCDs 34A and 34B, respectively, when the mirror block 20 is moved from the standard correct position by φ1. As shown in FIG. 6B, the right side of the left image, and the left side of the right image become dark. The remaining portions of the two images become bright.

[0197] FIG. 7A shows the mirror block 20 displaced from the standard correct position by +φ2 (i.e., in the positive y-axis direction). In this case, the fraction of the left light beam LL, the right light beam LR and the center light beam L0 that is incident on the left mirror surface 20bis increased.

[0198] FIG. 7B shows the effect on the right and left images detected by the CCDs 34A and 34B, respectively, when the mirror block 20 is moved from the standard correct position by +φ2. As shown in FIG. 7B, the left image becomes bright, while the right image becomes dark.

[0199] FIG. 8A shows the mirror block 20 displaced from the standard correct position by +φ3 (i.e., rotated about the x-axis in the clockwise direction). In this case, the left light beam LL, the right light beam LR and the center light beam L0 are reflected such that they are not incident on the upper-part of the mirrored surface 31aor the lower part of the mirrored surface 31b.

[0200] FIG. 8B shows the effect on the right and left images detected by the CCDs 34A and 34B, respectively, when the mirror block 20 is moved from the standard correct position by +φ3. As shown in FIG. 8B, the lower portion of the left image and the upper portion of the right image becomes dark, while the remaining portions of the two images become bright.

[0201] FIG. 9A shows the mirror block 20 displaced from the standard correct position by +φ4 (i.e., rotated about the y-axis in the clockwise direction). In this case, the left light beam LL, the right light beam LR and the center light beam L0 are reflected such that they are not incident on the lower part of the mirrored surface 31aor the lower part of the mirrored surface 31b.

[0202] FIG. 9B shows the effect on the right and left images detected by the CCDs 34A and 34B, respectively, when the mirror block 20 is moved from the standard correct position by +φ4. As shown in FIG. 9B, the lower portion of the left image and the lower portion of the right image becomes dark, while the remaining portions of the two images become bright.

[0203] FIG. 10A shows the mirror block 20 displaced from the standard correct position by +φ5 (i.e., rotated about the z-axis in the clockwise direction). In this case, the left light beam LL, the right light beam LR and the center light beam L0 are reflected such that they are not incident on the left part of the mirrored surface 31aor the left part of the mirrored surface 31b.

[0204] FIG. 10B shows the effect on the right and left images detected by the CCDs 34A and 343, respectively, when the mirror block 20 is moved from the standard correct position by +φ5. As shown in FIG. 10B, the left side of the left image and the left side of the right image becomes dark, while the remaining portions of the two images become bright.

[0205] Thus, as described above, the position of the mirror block 20 relative to the exit pupil, and the optical axes Ax1, Ax2, and Ax3, is critical if the brightness of the left and right images is to be uniform, and the three-dimensional perspective is to be maintained.

[0206] Therefore, by detecting a difference between the brightness of different portions of each of the left and right images, and a difference in brightness between the left image and the right image, the direction for moving the mirror block 20, in order to achieve a uniform brightness of both images, can be determined.

[0207] First Embodiment

[0208] A first embodiment of the present invention, will be described with reference to FIGS. 1A, 1B, 2A and 2B.

[0209] The position of the mirror block 20 is adjustable in the x and y directions between a pair of parallel guide plates 42aand 42b(see FIG. 2B), by an adjusting mechanism 40. The adjusting mechanism 40 includes a holding frame 41, which is attached to a base portion of the mirror block 20, and a first screw 44, which is fitted into the holding frame 41. A first motor 60 is attached to the base of the mirror block 20, and has a pinion 60A. A first gear 44A is meshed with the pinion 60A, and is also meshed with the first screw 44. When the first motor 60 is driven, the pinion 60A rotates the first gear 44A and thereby moves the screw 44 in the y direction.

[0210] A second screw 45 is fitted through a holding wall 2aof the observing portion 2. A nut portion 45aformed on the head of the second screw 45 is engaged with the first screw 44. A second motor 61 is attached to the inside of the holding wall 2a,and has a pinion 61a.A second gear 46 which is meshed with the pinion 61aand the second screw 45, is installed inside the holding wall 2a.When the second motor 61 is driven, the pinion 61A rotates the second gear 46 and thereby moves the screw 45 in the x direction.

[0211] Thus, as described above, the mirror block 20 is supported by the first screw 44 that is held by the second screw 45 which is fitted through the holding wall 2a.Further, by driving the motors 60 and 61, the position of the mirror block 20 can be adjusted in the x and y directions, until the ridge line between the mirrored surfaces 20aand 20b,is coincident with the exit pupil Ep and the optical axis Ax1, of the primary optical system 10. Furthermore, the effect on the left and right images formed at the imaging devices 34aand 34bdescribed above, can be used to determine which direction the mirror block 20 should be moved in order to restore uniform brightness to the detected images.

[0212] As shown in FIG. 1A, a light source 300 outputs a diffuse light having a uniform brightness. The light is incident on the primary optical system 10, and transmitted to the observing unit 2

[0213] As shown in FIG. 1B, an image signal is output from each of the imaging devices 34aand 34band is sent to a processor 100. More specifically, picture data contained within the image signal is stored in memories 101 and 102, respectively. The picture data of one image is compared with the picture data of the other image by a calculating device 105. The calculating device 105 outputs a driving signal to a controller 106. The controller 106 controls the first motor 60 and second motor 61 to drive the mirror block 20 to a position (i.e., the standard correct position) which will result in a uniform brightness of the left and right images.

[0214] Once the mirror block 20 has been adjusted to standard correct position, the picture data for the left and right images are further processed by a video processor 103 and output to a monitor 190 A timing controller 104 controls the video processor to alternately output the left and right image to the monitor 190. An observer wears a pair of glasses 191 that has shutters such as liquid crystal shutters in a viewfields of each eye. The shutters are controlled by the timing controller 104 to be alternately open and shut, such that the image on the monitor 190 can be viewed by only one eye at one time. The timing controller 104 outputs control signals corresponding to the output timing of the picture data of the video processor 103. Therefore, the shutter in front of the right eye of the glasses 191 blocks the light when the left picture is displayed on the monitor 190. Conversely, the shutter of left eye blocks the light when the right picture is displayed.

[0215] The pair of glasses 191 allow an observer to view the left picture taken by the left image sensing element 34ausing only the left eye, and the right picture taken by the right image sensing element 34bby using only the right eye. Therefore, the observer is able to view a three dimensional image of the object.

[0216] Thus, as described above, the difference in brightness between the left and right images, and the difference in brightness between each image is detected. Then, the position of the mirror block 20 is automatically adjusted to the standard correct position.

[0217] The calculating device 105 and the controller 106 are only used during the adjustment and are not used during the observation.

[0218] The operation of the calculating device 105, and the detection of the image brightness will be described with reference to FIGS. 11A through 11J and 12A through 12D.

[0219] FIGS. 11A through 11J show the brightness of the left and right images when the mirror block 20 has been moved in one of the directions or rotations φ1 through φ5.

[0220] As shown in FIGS. 11A through 11J, there are five brightness detection zones, A1, A2, A3, A4 and A5, respectively. The intensities I1, I2, I3, 14 and I5 are measured for the detection zones, A1, A2, A3, A4 and A5, respectively. Each intensity may be the output of one picture cell or an average of a group of cells Table 1 below summarizes the displacement of the mirror block 20 from the standard correct position corresponding to each of the FIGS. 11A through 11J, as well combinations of two types of displacements. In Table 1, “d” denotes “dark”, “b” denotes “bright”, “vd” denotes “very dark”, and “vb” denotes “very bright”. These terms are relative to a standard-brightness, which is defined as the brightness of the each of the left and right images when the mirror block 20 is located at the standard correct position. In Table 1, the intensities which have no data have the standard brightness level.

[0221] The first six rows in Table 1 (i.e., A through F) show the intensities I1 through I5 for each of the detecting zones A1 trough A5 as a result of the displacement of the mirror block 20, along one of the axes. The resulting left and right image patterns detected by the imaging devices 34aand 34b,respectively, are shown in FIGS. 11A through 11F, respectively. Therefore, by comparing the intensities I1 through I5 of the image sensor areas A1 through A5 of the left image, with the intensities I1 through I5 of the image sensor areas A1 through A5 of the right image, it is possible to detect the position of the mirror block 20 relative to the standard correct position. Further, the direction in which the mirror block 20 should be moved in order to return to the standard correct position can be determined.

[0222] The next four rows in Table 1 (i.e., G through J) show the intensities I1 through I5 for each of the detecting zones A1 trough A5 as a result of the rotation of the mirror block 20, about one of the axes. The resulting left and right image patterns detected by the imaging devices 34aand 34b,respectively are shown in FIGS. 11G through 11J, respectively. Therefore, by comparing the intensities I1 through I5 of the image sensor areas A1 through A5 of the left image with the intensities I1 through I5 of the image sensor areas A1 through A5 of the right image, it is possible to detect the position of the mirror block 20 relative to the standard correct position. Further, the direction in which the mirror block 20 should be rotated in order to return to the standard correct position can be determined.

[0223] As shown in Table 1, if the displacement of the mirror block 20 from the standard correct position usually occurs in only one direction (i.e., movement along only one axis, or rotation about one axis), then by detecting whether each of the intensities I1 through I5 of each of the images is darker or brighter than the standard brightness, the calculating device 105 can determine which direction the mirror block 20 must be moved. Therefore, only 1 bit of information is required for processing.

[0224] However, in the case that the mirror block 20 has been displaced along two or more axes, then more information may be required.

[0225] In Table 1, examples K through R illustrate examples of the mirror block 20 having been displaced in two directions from the standard correct position. In these cases, the intensities I1 through I5 are either very bright, very dark or have the standard brightness. However, the image patterns for each of the examples A through R, is unique and therefore, for the image patterns of examples K through R, only 1 bit of information is required in order to determine the direction in which the mirror block 20 should be moved.

[0226] However, other combinations of displacements in which the image pattern is similar to those listed above, but which have intensities that have more than one bright level and more than one dark level, 2 or more bits of information will be required.

[0227] If 8 bits of information are used, then the calculating device 105 can also determine the amount of displacement of the mirror block 20 from the standard correct position.

[0228] The methods of adjusting the location of the mirror block 20 based on the detected intensities I1 through I5 will be described below with reference to FIGS. 12A through 12D.

[0229] First Method

[0230] FIG. 12A shows a flowchart of a first method of adjusting the position of the mirror block 20. In this method, the amount of displacement necessary to position the mirror block 20 at the standard correct position is determined by solving a set of simultaneous linear equations. In this method, the number of intensities detected is equivalent to the number of degrees of freedom of the mirror block 20. Therefore, since the mirror block 20 has five degrees of freedom, five of the ten intensities (i.e. I1 through I5 for each of the left and right images) detected are used for determining the adjustment amount of the mirror block 20.

[0231] In step S11, the image data from the imaging devices 34aand 34bare transferred to the memories 101 and 102, respectively. Then in step S13, the intensities I1 through I5 for each of the left and right images are determined. in step S15, a total of five intensities of the ten intensities are selected. In step S17, the calculating device 105 uses simultaneous linear equations to determine the amount and direction of movement of the mirror block 20, required to move the mirror block 20 back to the standard correct position. The calculating device 105 then outputs a signal to the controller 106, which indicates the amount and direction of movement required to position the mirror block 20 at the standard correct position.

[0232] In step 19, the controller 106 controls the first motor 60 and the second motor 61 to drive the first gear 44aand the second gear 46 by a calculated amount, in order to move the mirror black 20 to the standard correct position. The routine then ends.

[0233] Thus, as described above, the first method can quickly calculate the amount and direction of movement required to move the mirror block 20 to the standard correct position, since the image data only needs to be detected once.

[0234] However, the first method requires that the intensity values change linearly with a change in displacement of the mirror block 20. If the mirror block 20 is located at a position where a rotation of the mirror block 20 is required in order to return the mirror block 20 to the standard correct position, another method of determining the amount and direction of movement of the mirror block 20 is required.

[0235] Second Method

[0236] FIG. 12B shows a second method of determining the amount and direction of movement of the mirror block 20, required to move the mirror block 20 to the standard correct position. In the second method, the calculating device 105, stores standard intensity values for the left and right images when the mirror block 20 is at the standard correct position. The actual intensity values are compared with the standard intensity values, and the mirror block 20 is moved based on a difference between the actual intensity values and the standard intensity values. Then the process is repeated until the two sets of values are the same.

[0237] Steps S21 through S25 are similar to steps S11 through S15 of the first method shown in FIG. 12A. Therefore, in step S21, the image data from the imaging devices 34aand 34bare transferred to the memories 101 and 102, respectively. Then in step S23, the intensities I1 through I5 for each of the left and right images are determined. In step S25, a total of five intensities of the ten intensities are selected.

[0238] In step S27, the calculating device 105 compares the intensities with the standard data, and determines whether the intensities are within an allowable range of the standard data by calculating the difference between the two sets of data using the least square method. If the difference between the two sets of data is less than a predetermined value (S27:Y), then the routine ends.

[0239] If the difference between the two sets of data is not less than the predetermined value (S27:N), then in step S29, the calculating device 105 determines the direction and amount of compensation required to move the mirror block 20 to the standard correct position.

[0240] In step 31, the controller 106 controls the first motor 60 and the second motor 61 to drive the first gear 44aand the second gear 46 by the calculated-amount, in order to move the mirror block 20 to the standard correct position. Control then returns to step S21, where the above process is repeated.

[0241] As, described above, the process of measuring the intensities I1 through I5 for each of the left and right images, and the driving of the mirror block 20 to a new position in accordance with a difference between the measured intensities and the standard values, is repeated until the mirror block 20 is positioned at the standard correct position.

[0242] Third Method

[0243] FIG. 12C shows a third method of determining the amount and direction of movement of the mirror block 20, required to move the mirror block 20 to the standard correct position. In the third method, a reference look up table which cross references displacement amounts with intensities (similar to Table 1) is used.

[0244] As shown in FIG. 12C, steps S41 through S49, are similar to the steps S21 through S29 of the second method shown in FIG. 12B.

[0245] Therefore, in step S41, the image data from the imaging devices 34aand 34bare transferred to the memories 101 and 102, respectively. Then in step S43, the intensities I1 through I5 for each of the left and right images are determined. In step S45, a total of five intensities of the ten intensities are selected.

[0246] In step S47, the calculating device 105 compares the intensities with the standard data, and determines whether the intensities are within an allowable range of the standard data by calculating the difference between the two sets of data using the least square method. If the difference between the two sets of data is less than a predetermined value (S47:Y), then the routine ends.

[0247] If the difference between the two sets of data is not less than the predetermined value (S47:Y), then in step S49 the calculating device 105 looks up a direction of movement for compensating the position of the mirror block 20 in accordance with the measured intensities. The controller 106 then controls the first motor 60 and second motor 61 to drive the mirror block 20 by a predetermined amount and in the direction determined from the look up table. The control then proceeds to step S41, where the above process is repeated, until the difference between the intensities and the standard values is below the predetermined amount.

[0248] As, described above, the process of measuring the intensities I1 through I5 for each of the left and right images, and the driving of the mirror block 20 to a new position in accordance with a value in the reference table, is repeated until the mirror block 20 is positioned at the standard correct position.

[0249] Fourth Method

[0250] FIG. 12D shows a fourth method of determining the amount and direction of movement of the mirror block 20, required to move the mirror block 20 to the standard correct position. The fourth method also uses the reference look up table which cross references displacement amounts with intensities used in the third method. However, the fourth method is also similar to the first method, where the procedure is executed only once, and the mirror block 20 is moved to the standard correct position immediately.

[0251] As shown in FIG. 12D, steps S61 through S65 are similar to the steps S11 through S15 of the second method shown in FIG. 12A.

[0252] Therefore, in step S61, the image data from the imaging devices 34aand 34bare transferred to the memories 101 and 102, respectively. Then in step S63, the intensities I1 through 15 for each of the left and right images are determined. In step S65, a total of five intensities of the ten intensities are selected.

[0253] Then in step S67, the calculating device 105 looks up a direction and amount of compensation corresponding to the measured intensities. The controller 106 then controls the first motor 60 and second motor 61 to drive the mirror block 20 by the amount and in the direction determined from the look up table, in step S71. The mirror block 20 will then be located at the standard correct position.

[0254] As described above, there are four methods of positioning the mirror block 20 at the standard correct position. The first and fourth method determine an amount and direction of movement required to move the mirror block 20 to the standard correct position, while the second and third method determine a direction that the mirror block 20 should be moved in order to attain the standard correct position. However, the mirror block 20 is moved by a predetermined amount and the process is repeated until it is determined that the mirror block 20 is at the standard correct position.

[0255] Thus, only direction data needs to be determined when using the second and third method, and therefore only 1 or 2 bits of data is required. The first and fourth methods will position the mirror block 20 at the standard correct position more quickly, but require 8 bits of data.

[0256] Second Embodiment

[0257] FIG. 13 shows a block diagram of a stereoscopic endoscope according to a second embodiment of the present invention. The second embodiment is similar to the first embodiment shown in FIG. 1, with the common parts having the same reference numerals.

[0258] The second embodiment is provided with an observation processing device 100aand an adjustment processing device 100b,instead of the processing device 100 of the first embodiment.

[0259] As shown in FIG. 13, the observation processing device 100ais provided with the memories 101 and 102, the video processor 103, and the timing controller 104. The adjustment processing device 100bis provided with the calculating device 105, and the controller 106. Further, the memories 101 and 102 are electrically connected to the calculating device 105.

[0260] The movement of the mirror block 20 to the standard correct position is done in a similar manner to that described for the first embodiment above. However, the adjustment of the position of the mirror block 20 is usually done in the factory, and therefore, it is only necessary to connect the adjustment processing device 100bto the endoscope during the adjustment operation. Furthermore, during normal operation of the stereoscopic endoscope, only the observation processing device 100ais required. This reduces the overall size of the stereoscopic endoscope unit required in the field.

[0261] Third Embodiment

[0262] FIG. 14 shows a sectional view of a stereoscopic endoscope according to a third embodiment of the present invention. The third embodiment includes the insertion portion 1 and an observing portion 200

[0263] The observing portion 200 is similar to the observing portion 2, with the adjustment mechanism 40 attached to a holding wall 200a,and other common parts having the same reference numerals. However, the observing portion 200 includes the calculating device 105, the memories 101 and 102, and the controller 106. Therefore, the adjustment of the position of the mirror block 20 can be done without connecting an external device. This facilitates the readjustment of the position of the mirror block 20 in the field, as well as the initial adjustment done in the factory. Further, the overall size of the stereoscopic endoscope is reduced.

[0264] An observation processor 100cwhich includes the video processor 103 and the timing controller 104 can be connected to observing portion 200 to allow viewing of the images displayed on the monitor 190 while wearing the pair of glasses 191.

[0265] Fourth Embodiment

[0266] FIG. 15A shows a sectional view of a stereoscopic endoscope according to a fourth embodiment of the present invention. The fourth embodiment includes the insertion portion 1 and an observing portion 201.

[0267] The observing portion 201 is similar to the observing portion 2, with the common parts having the same reference numerals. However, in the fourth embodiment, the mirror block 20 is attached to a mounting frame 41a,which is attached to a holding wall 201a.A mounting screw 401 and nut 402 secure the mounting frame 41ato the holding wall 201a.The mounting screw 401 passes through a hole 201bof the holding wall 201a.The shape of the hole 201bis slightly oblong in the y direction, to allow the mounting screw to be offset from the center of the hole 201bin the y direction, as shown in FIG. 15B.

[0268] As further shown in FIG. 15B, the observation processing device 100ahas the same arrangement as the second embodiment. An adjustment processing device 100dis provided with the memories 101 and 102, the calculating device 105 and correction value indicator 107. The calculating device 105 determines the displacement of the mirror block 20 from the standard correct position based on the image data, and the indicator 107 displays the correction value for the y-axis direction as numerical information. The correction value refers to the direction and amount of movement required to position the mirror block 20 at the standard correct position.

[0269] Therefore, by using the numerical information, the mounting block can be manually positioned by adjusting the position of the mounting screw 401 with respect to the center of the hole 201b.

[0270] As described above, the fourth embodiment of the endoscope does not require a driving mechanism to move the mirror block 20 to the standard correct position, and therefore the number of parts and the cost of manufacturing the endoscope is reduced.

[0271] Fifth Embodiment

[0272] FIG. 16 shows a sectional view of a stereoscopic endoscope according to a fifth embodiment of the present invention. The fifth embodiment includes an insertion portion 1aand an observing portion 202.

[0273] The observing portion 202 is similar to the observing portion 2, and the insertion portion 1ais similar to the insertion portion 1, with the adjustment mechanism 40 attached to a holding wall 202aand the other common parts having the same reference numerals. However, the insertion portion 1ais designed to be used with a non-stereoscopic endoscope, and is attached to the observing portion 202 using an adapter 50. The insertion portion 1ais normally provided with a hood 14 that is attached around the circumference of the image-side end of the insertion portion 1a.The hood 14 allows an observer to directly view the image formed by the insertion portion 1a,while preventing external ambient light from entering the observer's eye. The observing portion 202 is connected with the insertion portion 1athrough the adapter 50 that is clamped on the hood 14.

[0274] The adapter 50 comprises a holding ring 51 that is attached to the hood 14 from the observing portion side. Clamps 52 are attached to the holding ring 51 using bolts 53. Further, the clamps 52 are positioned on the insertion portion side of the hood 14. By tightening the bolts 53, the space between the clamps 52 and the holding ring 51 is reduced, and the hood 14 is securely attached to the holding ring 51. In FIG. 16, each of the clamps 52 is shown attached to the holding ring 51 using a single bolt. However, three bolts should be used to in order to securely attach the hood 14 to the holding ring 51.

[0275] The holding ring 51 consists of a base plate portion 51athat has an opening to allow light to pass through, a cylindrical portion 51bthat encloses the hood 14, and an inner flange portion 51cto which the clamps 52 are fixed. The hood 14 is clamped between the base plate portion 51aof the holding ring 51 and the clamps 52. In the preferred embodiment the clamps 52 are L-shaped.

[0276] The holding ring 51 is attached to an outer flange 202bof the observing portion 202 using at least three adjusting bolts 54.

[0277] The adjusting bolts 54 are fed through holes 202cand are fixed to the outer flange 202bby fastening nuts 55 and 56, which are positioned on either side of the outer flange 202b.Since the positions of the nuts 55 and 56 are changed together, the distance between the insertion portion 1 and the observing portion 202 along the adjusting bolt 54 changes. Therefore, the relative attitude of the insertion portion 1aand the observing portion 202 can be adjusted three-dimensionally by adjusting each of the adjusting bolts 54 independently.

[0278] Further, the adjusting mechanism 40 is more effective in the fifth embodiment, since the relative attitude of the insertion portion 1aand the observing portion 202 can be changed in the fifth embodiment.

[0279] Sixth Embodiment

[0280] FIG. 17 shows a sectional view of a stereoscopic endoscope according to a sixth embodiment of the present invention. The sixth embodiment includes the insertion portion 1aand an observing portion 203. The observing portion 203 is similar to the observing portion 202, with the common parts having the same reference numerals. In this case, the adapter 50 is attached to a flange 203bby the bolts 54 which pass through the holes 203cand are fastened using the nuts 55 and 56.

[0281] FIGS. 18A and 18B show an enlarged view of an adjustment mechanism 40aof the observing portion 203. The mechanism 40aincludes a holding base 42 which holds the mirror block 20 and permits movement along the x-axis direction and the y-axis direction.

[0282] The holding base 42 is supported by a rotation plate 47 with three adjusting bolts 48a,48band 48c.The rotation plate 47 is attached to a holding wall 203aof the observing portion 203 by an axis pin 49 so as to permit rotation about the axis pin 49. Compression springs are arranged around the adjusting bolt 48a,48band 48cto maintain the attitude of the holding base 42.

[0283] The attitude of the holding base 42 changes by tightening or loosening the adjusting bolts 48a,48band 48c.Further, the adjustment of these bolts allows the mirror block 20 to be rotated about the y-axis and the z-axis. The adjustment of the rotation plate 47 allows the mirror block 20 to be rotated about the x-axis.

[0284] Therefore, as described above, the mirror block 20 can be adjusted along the 5 degrees of freedom.

[0285] Seventh Embodiment

[0286] FIG. 19 shows a sectional view of a stereoscopic endoscope according to a seventh embodiment of the present invention. The seventh embodiment includes the insertion portion 1aand an observing portion 204. The observing portion is similar to the observing portion 202, with the common parts having the same reference numerals. However, the mirror block 20 is directly attached to a holding wall 204aof the observing portion 204.

[0287] In the seventh embodiment, the adapter 50 is connected to the observing portion 204 through two L-shaped coupling plates 57. The mirror block 20 is fixed to the observing portion 204 such that its position cannot be adjusted.

[0288] The adapter 50 has the three adjusting bolts 54, with at least two of the adjusting bolts 54 being attached to the observing portion 204 through the coupling plates 57. The nuts 55 and 56 that are positioned on either side of each coupling plate 57, and secure one end of the coupling plate 57 to one of the adjusting bolts 54. The other end of the coupling plate 57 is provided with fixing screw 57b.

[0289] The coupling plate 57 is fastened to a fixing plate 204dof the observing portion 204 using nuts 58 and 59 which are fastened to the fixing screw 57bon both sides of the fixing plate 204d.

[0290] The adjustment of the nuts 58 and 59 allows the relative attitude of the insertion portion 1ato the observing portion 24 to be changed in the y-axis direction. Further, by adjusting the nuts 55 and 56 that are attached to the adjusting bolts 54, the relative attitude of the insertion portion 1ato the observing portion 204 may be changed in order to change the three-dimensional effect.

[0291] Therefore, as described above, the change in the three-dimensional effect of the image can be achieved without using the adjustment mechanism 40. This decreases the number of parts, and reduces the cost of manufacturing the stereoscopic endoscope.

[0292] Eighth Embodiment

[0293] FIG. 20 shows a sectional view of a stereoscopic endoscope according to an eighth embodiment of the present invention. The eighth embodiment includes the insertion portion 1aand an observing portion 205. The observing portion 205 is similar to the observing portion 204, with the mirror block 20 attached to a holding wall 205 and the other common parts having the same reference numerals. Thus, the eighth embodiment is similar to the seventh embodiment shown in FIG. 19, except for the construction around each coupling plate 57. In the eighth embodiment, two coupling plates are provided. The construction around one of the coupling plates 57 will be described below.

[0294] A first adjusting gear 56ais installed on the coupling plate 57 and rotates about an axis. The adjusting bolt 54 is screwed through the opening 57a.The first adjusting gear 56ais meshed with the adjusting bolt 54 and a first pinion 62aof a first motor 62. The first motor 62 is mounted on the coupling plate 57.

[0295] A second adjusting gear 58ais installed inside the observing portion 205, and rotates about an axis. The fixing screw 57bis screwed through an opening 205eformed in the observing portion 205. The second adjusting gear 58 is meshed with the fixing screw 57band with a second pinion 63aof a second motor 63. The second motor 63 is mounted on an inside wall of the observing portion 205.

[0296] According to the construction shown in FIG. 20, since the two first motors 62 are driven simultaneously, the position of the insertion portion 1aalong the y axis can be adjusted. Further as the two second motors 63 are driven simultaneously, the position of the insertion portion 1acan be adjusted in the x-axis direction.

[0297] Therefore, the three-dimensional effect on the observed image can be controlled by driving the pair of first motors 62 and the pair of second motors 63.

[0298] Ninth Embodiment

[0299] FIG. 21A shows a sectional view of a stereoscopic endoscope according to a ninth embodiment of the present invention. The ninth embodiment includes the insertion portion 1 and an observing portion 206. The observing portion 206 is similar to the observing portion 2 shown in FIG. 1A, with the adjustment mechanism 40 attached to a holding wall 206a,and the other common parts having the same reference numerals. However, the observing portion 206 has a single imaging device 34c,and two secondary optical systems 30cand 30d.The secondary optical systems 30cand 30dare similar to the secondary optical systems 30aand 30bbut include a pair of imaging lenses 32cand 32d,a second pair of mirrors 31cand 31d,and a third pair of mirrors 31eand 31f.

[0300] As shown in FIG. 21A, the light divided by the mirror block 20 is transmitted by the pair of the secondary optical systems 30cand 30d,and a pair of images are formed on the imaging device 34c.The images are formed on separate areas of the imaging device 34cand do not overlap each other.

[0301] The output data from the imaging device 34cis input into a processing device 100ethat processes the data to display a picture of the object on the monitor 190, as shown in FIG. 21B. The processing device 100eis similar to the processing device 100a,with similar parts having common reference numerals.

[0302] The output data from the imaging device 34c,which is the combined data of the left and right pictures, is separated by an area division circuit 108 into a pair of images that correspond to the left and right image formed by each the secondary optical system 30cand 30d.The separated picture data are stored into the picture memories 101 and 102 and are alternatively displayed in time sequence on the monitor 190, as described above.

[0303] Therefore, in the ninth embodiment, only a single imaging device is required, and thus the cost of manufacturing the stereoscopic endoscope can be reduced.

[0304] Tenth Embodiment

[0305] FIG. 22A shows a sectional view of a stereoscopic endoscope according to a tenth embodiment of the present invention. The tenth embodiment includes the insertion portion 1 and an observing portion 207.

[0306] The observing portion 207 is similar to the observing portion 206 shown in FIG. 21, with the adjustment mechanism 40 attached to a holding wall 207a,and the other common parts having the same reference numerals. However, in the observing portion 206 the images of the pair of the secondary optical systems 30cand 30dare formed in the same area of an imaging device 34d.As a result, the imaging device 34dof the tenth embodiment is only half the size of the imaging device 34cused in the ninth embodiment. Further, a half mirror prism 80 replaces the third pair of mirrors 31eand 31f.Each of the half mirrors 80aand 80breceives light through one of a pair of liquid crystal shutters 81 and 82.

[0307] Since the images formed by both of the secondary optical systems 30cand 30d,completely overlap on the imaging device 34d,then one of the left and right images must be blocked while the other image is detected in order to independently receive the left and right images. Therefore, the liquid crystal shutters 81 and 82 alternatively transmit light reflected from the second mirrors 31cand 31d,to the half mirror prism 80.

[0308] As shown in FIG. 22B, a processing device 100fmay be provided which is similar to the processing device 100 and which has the timing controller 104 which controls the liquid crystal shutters 81 and 82, a time division circuit 109 and the shutters of the glasses 191, to operate in synchronism, thereby ensuring that the proper image is seen by the corresponding eye. The output data of the imaging device 34dis divided into the left and right picture data by the time division circuit 109, with each picture being separately stored into the memories 101 and 102, respectively. The video processor 103 alternatively displays the left and right pictures according to clock signal from the timing controller 104 and the shutters of the glasses 191 are driven synchronously with the switching of the picture on the monitor 190.

[0309] Eleventh Embodiment

[0310] FIG. 23 shows a sectional view of a stereoscopic endoscope according to an eleventh embodiment of the present invention. The eleventh embodiment of the stereoscopic endoscope includes the insertion portion 1, and an observing portion 208. The observing portion 208 has a mirror block 21, a pair of secondary optical system 30eand 30f,and an illumination unit 90, used to illuminate the object being observed with the endoscope.

[0311] The secondary optical systems 30eand 30fare similar to the secondary optical systems 30aand 30bof the observing portion 2, except that imaging lenses 22aand 22bare used instead of the imaging lenses 35aand 35b.The imaging lenses 22aand 22bare positioned between the mirror block 21 and the mirrors 31aand 31b,respectively. Further, the mirror block 21 is fixed in position.

[0312] The illumination unit 90 includes a light source 91a,condenser lens 92 and an optical fiber bundle 93. Two light beams L1 and L2 emitted from the illumination unit 90 are transmitted through the insertion portion 1 to the object to be viewed. The illumination unit 90 is arranged so that the light beam emitted from the light source 91 does not interfere with the light beam incident on the mirror block 21 that is reflected by the object.

[0313] FIG. 24 is a front view of the mirror block 21 viewed from the object side, showing a relationship of the illuminating light beams L1 and L2, and the observing fields E1 and E2 on the exit pupil Ep of the primary optical system 10. As shown in FIG. 24, the illuminating light beams L1 and L2 do not overlap the observing fields E1 and E2.

[0314] Therefore, as described above, an optical fiber is not required to transmit the illuminating light to the end of the insertion portion 1. Therefore, the cost of manufacturing the stereoscopic endoscope can be reduced.

[0315] Twelfth Embodiment

[0316] FIG. 25 shows a sectional view of a stereoscopic endoscope according to a twelfth embodiment of the present invention. The twelfth embodiment includes the insertion portion 1 and an observing portion 209.

[0317] The observing portion 209 is similar to the observing portion 2 of the first embodiment, and includes a pupil dividing mechanism 120, a first secondary optical system 130aand a second secondary optical system 130b.The pupil dividing mechanism 120 consists of two mirrors 121 and 122. A distance between the two mirrors 121 and 122 can be changed in the y-axis direction (i.e., the left-right direction), by an adjusting mechanism 140.

[0318] The first secondary optical systems 130aincludes mirrors 31a,imaging lenses 132aand 135a,and an eyepiece lens 133a.The secondary optical systems 130bincludes mirrors 31b,imaging lenses 132band 135b,and an eyepiece lens 133b.The eyepiece lenses 133aand 133ballow an observer to directly view the object.

[0319] The adjusting mechanism 140 includes a holding frame 141, which is formed on a base portion of the pupil dividing mechanism 120, and a first screw 144, which is fitted into the holding frame 141. A first gear 144A is meshed with the first screw 144. By rotating the first gear 144A, the first screw 144 is moved in the y direction

[0320] A second screw 145 is fitted through a holding wall 209aof the observing portion 209. A nut portion 145aformed on the head of the second screw 145 is engaged with the first screw 144. A second gear 146 which is meshed with the second screw 145, is installed inside the holding wall 209a.By rotating the second gear 146 the screw 145 is moved in the x direction.

[0321] A third adjusting screw 143 is also supported by the holding frame 141. Stems 121aand 122athat are formed behind the mirrors 121 and 122 have threaded through holes, and are threaded with the third adjusting screw 143.

[0322] As shown in FIG. 26A, a third adjusting gear 143ais formed at the center of the third adjusting screw 143. Further, the third adjusting screw 143 is formed such that a direction of the threading of the adjusting screw 143 on one side of the adjusting gear 143ais opposite to a direction of the threading of the adjusting screw 143 on the other side of the adjusting gear 143a.FIG. 26B shows a side view of the pupil dividing mechanism 120. The pupil dividing mechanism 120 is arranged between guide plates 142aand 142bso that the rotation of adjusting gear 143aresults in the linear movement of the mirrors 121 and 122 along the axis of the screw 143, as described above.

[0323] The position of the mirrors 121 and 122 are changed synchronously, in the x-axis direction and the y-axis direction by rotating the first and second adjusting gears 144aand 146, respectively. When the positions of each of the mirrors 121 and 122 are correctly adjusted, a tip 121bof the mirror 121 and a tip 122bof the mirror 122 coincide with the optical axis Ax1 of the primary optical system 10 and a plane which includes the exit pupil.

[0324] The distance between the mirrors 121 and 122 is adjusted by rotating the third adjusting gear 143a.When the third adjusting gear 143ais rotated in one direction, the mirrors 121 and 122 are separated from each other. When the third adjusting gear 143ais rotated in the opposite direction, the mirrors 121 and 122 are moved closer together. The third adjusting gear 143amay be driven manually or by using a motor.

[0325] As described above, light travels from the exit pupil Ep and is incident on the mirrors 121 and 122. By changing the distance between the mirrors 121 and 122, a distance traveled by the light from the exit pupil Ep to the mirrors 121 and 122, will change. The three-dimensional effect of the stereoscopic image viewed in the observing portion 209 varies according to the distance that the light has traveled. The effect of the change in the distance that the light has traveled will be described below.

[0326] FIG. 27A is a top view of the mirrors 121 and 122 showing a path of the light incident on the mirrors 121 and 122 when the tips 121band 122bof the mirrors 121 and 122 contact each other. FIG. 27B is a front view of the mirrors 121 and 122 when the tips 121band 122bof the mirrors 121 and 122 contact each other. Under this condition, since the distance traveled by the light is equal to the minimum value d0, the three-dimensional effect on the observed image is small. This is preferable for viewing an object that is located at a point near to the objective lens 11. Further, the amount light that is transmitted to the secondary optical systems 130aand 130bis a maximum, and therefore, a bright image is observed.

[0327] FIG. 28A is a top view of the mirrors 121 and 122 when the tips 121band 122bof the mirrors 121 and 122 are farthest apart. FIG. 27B is a front view of the mirrors 121 and 122 when the tips 121band 122bof the mirrors 121 and 122 are farthest apart. Under this condition, since the distance that the light has traveled is equal to the maximum value d1, the three-dimensional effect on the observed image is large. This is preferable for viewing an object that is located at a point far away from the objective lens 11.

[0328] As described above, the twelfth embodiment allows a observer to adjust the three-dimensional effect on the image observed.

[0329] Thirteenth Embodiment

[0330] FIG. 29 shows a sectional view of the observing portion 210 of a stereoscopic endoscope according to a thirteenth embodiment of the present invention. The observing portion 210 is similar to the observing portion 209 shown in FIG. 25 with the adjustment mechanism 140 attached to a holding wall 210a,and the other common parts having the same reference numerals.

[0331] The thirteenth embodiment also includes the insertion portion 1ashown in FIG. 16, and described above for the fifth embodiment. Thus, the insertion portion 1ais attached to the hood 14 and the adapter 50. The adapter 50 is then attached to a flange 210bof the observing portion 210 by passing the adjusting bolts 54 through holes 210cand securing the adjusting bolts 54 with nuts 55 and 56.

[0332] Therefore, in the thirteenth embodiment, an insertion portion for a non-stereoscopic endoscope can be used with the observing portion of the stereoscopic endoscope.

[0333] Fourteenth Embodiment

[0334] FIG. 30 shows a sectional view of a stereoscopic endoscope according to a fourteenth embodiment of the present invention. An observing portion 211 of the fourteenth embodiment includes the pupil dividing mechanism 120 and the adjustment mechanism 140 which is attached to a holding wall 211a.However, the observing portion 211 has a first secondary optical system 130cand a second secondary optical system 130d.The first and secondary optical systems 130cand 130dare similar to the optical systems 130aand 130bdescribed above, except that the imaging devices 134aand 134breplace the imaging lenses 135a,135band eyepiece lenses 133aand 133b,respectively.

[0335] Therefore, the imaging devices 134aand 134boutput an image signal representative of the right and left images respectively. The output image can be processed by the processing device 100 and viewed using the monitor 190 and the pair of glasses 191, as described for the first embodiment.

[0336] Further, the processing device 100 can also be used to determine a direction and amount of movement of the pupil dividing mechanism 120 in order to improve the three-dimensional effect, in a similar manner to the process described for the movement of the mirror block 20 in the fourth embodiment.

[0337] Fifteenth Embodiment

[0338] FIG. 31 shows a sectional view of a stereoscopic endoscope according to a fifteenth embodiment of the present invention. The fifteenth embodiment includes an observing portion 212 and the insertion portion 1a.The observing portion 212 is similar to the observing portion 211 of the fourteenth embodiment with the adjustment mechanism 140 being attached to a holding wall 212a,and the other common parts having the same reference numerals.

[0339] Thus, the insertion portion 1ais attached to the hood 14 and the adapter 50. The adapter 50 is then attached to a flange 212bof the observing portion 212 by passing the adjusting bolts 54 through holes 212cand securing the adjusting bolts 54 with nuts 55 and 56, in a similar manner to that described in the fifth embodiment, and shown in FIG. 16.

[0340] Therefore, in the fifteenth embodiment, an insertion portion for a non-stereoscopic endoscope can be used with the observing portion of the stereoscopic endoscope.

[0341] Sixteenth Embodiment

[0342] FIG. 32 shows a sectional view of a stereoscopic endoscope according to a sixteenth embodiment of the present invention. The sixteenth embodiment includes the insertion portion 1 and an observing portion 213. The observing portion 213 is similar to the observing portion 209 of the twelfth embodiment with the adjustment mechanism 140 being attached to a holding wall 213a,and the other common parts having the same reference numerals.

[0343] However, in the sixteenth embodiment, an imaging lens 35 and an imaging device 36 (such as a CCD) are located in between the mirrors 121 and 122. Therefore, when the mirrors 121 and 122 are separated, a portion of the light transmitted through the primary optical system 10 will be incident on the imaging lens 35, and an image will be formed on the imaging device 36. The imaging device 36 outputs an image signal which can be processed by a processing device such as the processing device 100, and shown on the monitor 190. With this construction, a three-dimensional image can be viewed through the eyepiece lenses 133aand 133b.Further, a regular two dimensional image can be viewed on an-external monitor.

[0344] Seventeenth Embodiment

[0345] FIG. 33 shows a sectional view of a stereoscopic endoscope according to a seventeenth embodiment of the present invention, in which a three-dimensional image can be viewed through the eyepiece lenses as well as displayed on a monitor.

[0346] The seventeenth embodiment has an observing portion 214, which is similar to the observing portion 209 of the twelfth embodiment. However, the adjustment mechanism 140 is attached to a holding wall 214a.Further, the observing portion 214 has a first secondary optical system 130eand a second secondary optical system 130f.The first secondary optical system 130eand the second secondary optical system 130fare similar to the first secondary optical system 130cand the second secondary optical system 130dof the previous embodiment, but also include a first half mirror 95alocated between the lenses 132aand 135a,and a second half mirror 95blocated between the lenses 132band 135b,as well as a pair of imaging devices 134aand 134b,respectively.

[0347] The first half mirror 95atransmits a portion of the light to the eyepiece lens 133a,and transmits the remaining portion of the light to the imaging device 134a.The second half mirror 95btransmits a portion of the light to the eyepiece lens 133b,and transmits the remaining portion of the light to the imaging device 134b.The imaging devices 134aand 134boutput left and right image signals to a processing device such as the processing device 100 shown in FIG. 1. Therefore, a three-dimensional image can be observed on the monitor 190 by wearing the pair of glasses 191 of the first embodiment.

[0348] Eighteenth Embodiment

[0349] FIG. 34 shows a sectional view of a stereoscopic endoscope according to an eighteenth embodiment of the present invention. The eighteenth embodiment includes an observing portion 215 and the insertion portion 1a.The observing portion 215 is similar to the observing portion 214 with the adjustment mechanism 140 being attached to a holding wall 215a,and the other common parts having the same reference numerals.

[0350] Thus, the insertion portion 1ais attached to the hood 14 and the adapter 50. The adapter 50 is then attached to a flange 215bof the observing portion 215 by passing the adjusting bolts 54 through holes 215cand securing the adjusting bolts 54 with nuts 55 and 56, in a similar manner to that described in the fifth embodiment, and shown in FIG. 16.

[0351] In the twelfth through eighteenth embodiments described above, the adjustment of the pupil dividing mechanism 120 can be automatically done using a combination of motors and image processing in a manner described for the first embodiment. Therefore, a processing device such as the processing device 100 can receive image information either directly through the imaging devices 134aand 134b,or by attaching an imaging device to each of the eyepiece lenses 133a,133b.Then, the amount and direction of movement required to move the pupil dividing mechanism 120 to its standard correct position can be determined.

[0352] Nineteenth Embodiment

[0353] FIG. 35 shows a sectional view of a stereoscopic endoscope according to a nineteenth embodiment of the present invention. The nineteenth embodiment includes an observing portion 216 and the insertion portion 1.

[0354] Light transmitted from the insertion portion 1 to the observing portion 216 is divided into left and right light beams by a half mirror 396, a mirror 323 and a mirror 324.

[0355] One half of the light beam transmitted through the half mirror 396 is reflected by the mirror 323 and transmitted through a first secondary optical system 330aand viewed by an observer. The first secondary optical system 330aincludes a mirror 331aan imaging lenses 332aand an eyepiece lens 333a.

[0356] The other half of light beam transmitted through the half mirror 396 is incident on a separator lens 337athat forms the right picture on the imaging device 334a.

[0357] Similarly, one half of the light beam reflected by the half mirror 396 is reflected by the mirror 324, and is transmitted through a second secondary optical system 330band viewed by an observer. The second secondary optical system 330bincludes an imaging lenses 332band an eyepiece lens 333b.

[0358] The other half of the beam reflected by the half mirror 396 is incident on a separator lens 337bthat forms the left picture on the imaging device 334b.

[0359] The imaging devices 334aand 334boutput left and right image signals respectively, to a processing device, such as the processing device 100 described above. Alternate left and right images are then displayed on a monitor and viewed wearing special glasses, such as the pair of glasses 191.

[0360] Further, the eyepiece lenses 333aand 333bhave inverting optics, thereby forming an erect image.

[0361] As described above, the stereoscopic endoscope according to the nineteenth embodiment allows direct three-dimensional viewing of the object, as well as three-dimensional viewing using a monitor, and a special pair of glasses. Therefore, many people can view the three-dimensional image simultaneously.

[0362] Twentieth Embodiment

[0363] FIG. 36 shows a sectional view of a stereoscopic endoscope according to a twentieth embodiment of the present invention. The twentieth embodiment includes an observing portion 217 and the insertion portion 1a.

[0364] The observing portion 217 is similar to the observing portion 216 described above, with common parts having the same reference numerals. The observing portion 217 has a base flange 217e,a cylindrical portion 217fand a top flange 217g.The base flange 217ehas an opening to allow light from the insertion portion 1ato be transmitted to the observing portion 217. The insertion portion 1ais attached to the hood 14 in a similar manner to that described for the fifth embodiment above. The hood 14 is securely fastened between the base flange 217eand the top flange 217gusing clamps 52 and bolts 53.

[0365] Twenty-first Embodiment

[0366] FIG. 37 shows a sectional view of a stereoscopic endoscope according to a twenty-first embodiment of the. present invention. The twenty-first embodiment includes an observing portion 218 and the insertion portion 1. The .observing-portion 218 includes a first secondary optical system 430aand a second secondary optical system 430b,and an adjustment mechanism 440. The first secondary optical system 430ahas a separator lens 437a,a fiber bundle 439aand an eyepiece lens 433a.Similarly, the second secondary optical system 430bhas a separator lens 437b,a fiber *bundle 439band an eyepiece lens 433b.

[0367] The separator lenses 437aand 437bare located in the exit pupil Ep (see, e.g, FIG. 38A) of the primary optical system 10 and form the left and right picture images at a first end surface of each of the fiber bundles 439aand 439b,respectively. The fiber bundles 439a,439btransmit the images to a second end surface thereof. The observer can then view the images through the eyepiece lenses 433aand 433b.

[0368] The adjustment mechanism 440 is similar to the adjustment mechanism 140 of the twelfth embodiment. Common parts have the same reference numbers and will not be described in detail below.

[0369] The adjustment mechanism 440 has a first support 447aand a second support 447b,each having a threaded through-hole. The third adjusting screw 143 is threaded through each of the through holes. The separator lens 437aand the first end portion of the fiber bundle 439aare fixed to the first support 447a,while the separator lens 437band the first end portion of the fiber bundle 439bare fixed to the second support 447b.The second ends of each of the fiber bundles 439aand 439bare fastened to the observing portion 218.

[0370] The third adjusting screw 143 is supported by the holding frame 141 at which the first adjusting screw 144 is fitted. The first adjusting gear 144ais fasten to the first adjusting screw 144 and the second adjusting screw 145 is fitted through holding wall 218aof the observing portion 218. The nut portion 145aformed on the top end of the second adjusting screw 145 is engaged with the first adjusting screw 144. The second adjusting gear 146 that is meshed with the second adjusting screw 145, is installed inside the holding wall 218a.

[0371] The third adjusting gear 143ais formed at the center of the third adjusting screw 143. Further, the direction of the threads on the third adjusting screw 143 on one side of the adjusting gear 143 are opposite the direction of the threads on the third adjusting screw 143 formed on the other side adjusting gear 143.

[0372] By rotating the first and second adjusting gears 144aand 146, the position of the separator lenses 437aand 437bin the x-axis and the y-axis directions can be changed simultaneously.

[0373] The distance between the separator lenses 437aand 437bis adjusted by -rotating the third adjusting gear 143a.When the third adjusting gear 143ais rotated in one direction, the lenses 437aand 437bare gradually separated, and by rotating the third adjusting gear 143ain the other direction, the lenses 437aand 437bare moved closer together. The fiber bundles 439aand 439bare flexible, and therefore bend when the first and second supports 447aand 447bare moved.

[0374] The change of the distance between the lenses 437aand 437bvaries the distance between the viewing fields, and therefore changes the three-dimensional effect of the image.

[0375] FIG. 38A shows the light path as seen by the right and left eyes E_Rand E_L, respectively, when the separator lenses 437aand 437bcontact each other. Under this condition, since the distance between the lenses 437aand 437bis equal to the minimum value d1, the three-dimensional effect of the view fields is small. This condition is preferable for observing an object that is located at a point near to the objective lens 11.

[0376] FIG. 38B shows the light path when the separator lenses 437aand 437bare furthest apart. Under this condition, since the distance between the lenses 437aand 437bis equal to the maximum value d2, the three-dimensional effect of the view fields is large. This condition is preferable for observing an object that is located at a point far away from the objective lens 11.

[0377] FIGS. 39A and 39B show-one modification to the twenty-first embodiment. In this modification, the separator lenses 437aand 437bare arranged to contact each other. A shading plate 425 is located in the center of the exit pupil and shades the central portion of the light beam that is incident on the separator lenses 437aand 437b.

[0378] The incident axes distance between the incident axes is equal to d3 when the shading plate 425 is removed, as shown in FIG. 39A. When the shading plate 425 is present, the distance between the incident axes is equal to d4, as shown in FIG. 39B. In this modification, d4 is larger than d3.

[0379] FIGS. 40A and 40B show two shading plates 426 and 427 which are modifications of the shading plate 425. Each of the shading plates 426 and 427 has apertures that define which areas of the light beams are to be incident on the separator lenses 437aand 437b.

[0380] The shading plate 426 in FIG. 40A, has a pair of apertures 426aand 426bthat are arranged symmetrically about the optical axis Ax1 of the primary optical system 10, and lie along the exit pupil Ep. The shading plate 427 has a pair of apertures 427aand 427bwhich are not arranged symmetrically, as shown in FIG. 40B.

[0381] As described above by using fiber bundles in the secondary optical systems, the number of parts which require precision positioning such as mirrors, can be reduced.

[0382] Twenty-second embodiment

[0383] FIG. 41 shows a sectional view of a stereoscopic endoscope according to a twenty-second embodiment of the present invention. The twenty-second embodiment has an observing portion 219 and the insertion portion 1a.The observing portion 219 is similar to the observing portion 218 of the twenty-first embodiment described above, with the adjustment mechanism 440 being attached to a holding wall 219a,and the other common parts having the same reference numerals.

[0384] Thus, the insertion portion 1ais attached to the hood 14 and the adapter 50. The adapter 50 is then attached to a flange 219bof the observing portion 219 by passing the adjusting bolts 54 through holes 219cand securing the adjusting bolts 54 with nuts 55 and 56, in a similar manner to that described in the fifth embodiment above.

[0385] Twenty-third Embodiment

[0386] FIG. 42A shows an enlarged portion of an observing portion 220 of a stereoscopic endoscope according to a twenty-third embodiment of the present invention. The observing portion is similar to the observing portion 219 of the twenty-first embodiment, with the common parts having the same reference numerals. Further, the twenty-third embodiment also includes the insertion portion 1, used in the first embodiment.

[0387] As shown in FIG. 42A, the observing portion 220 includes an illumination unit 490 used to illuminate an object to be viewed. The illumination unit 490 comprises the light source 491, the condenser lens 492 and the fiber bundles 493A, 493B. The emitted light beam from the illumination unit 490 is transmitted through the exit pupil Ep and insertion unit 1 to be incident on the object to be viewed. The illumination unit 490 is arranged so that the light beam emitted from the light source 491 does not interfere with the light beam that is reflected by the object and incident on the separator lenses 437aand 437b.

[0388] FIG. 42B is a front view of the exit pupil observed from the object side, and shows a relationship of illumination light beams L1 and L2, and effective fields E1 and E2 of the separator lenses 437aand 437b,respectively As shown in FIG. 42B, the illumination light beams L1 and L2 do not interfere with the effective fields E1 and E2 of the separator lenses 437aand 437b.

[0389] Twenty-fourth Embodiment

[0390] FIG. 43 shows a sectional view of a stereoscopic endoscope according to a twenty-fourth embodiment of the present invention. The twenty-fourth embodiment has the insertion portion 1 and an observing portion 221 The observing portion 221 is similar to the observing portion 218 of the twenty-first embodiment with the adjustment mechanism 440 being attached to a holding wall 221a,and the other the common parts having the same reference numerals.

[0391] The observing portion 221 includes an imaging device 434 instead of the eyepiece lenses 434aand 434b.The images transmitted by the fiber bundles 439aand 439bare formed on the imaging device 434 by the imaging lenses 432cand 432d.

[0392] In the twenty-fourth embodiment, the imaging lens 432cforms an image on a first area of the imaging device 434, while the imaging lens 432dforms an image on a second area of the imaging device 434. The first area and second area do not overlap each other.

[0393] The output data from the imaging device 434 is input into processing device, such as the processing device 100 of the first embodiment in FIG. 11, that processes the input data to display a three-dimensional picture of the object on the monitor. The output data from the imaging device 434 includes imaging data for both the left and right images. The imaging data is separated into the left and right picture data corresponding to the left and right images formed by each the imaging lens 432cand 432drespectively. The left and right picture data are alternatively displayed on the monitor, and viewed using the pair of glasses 191. This permits the viewing of a three-dimensional image.

[0394] Twenty-fifth Embodiment

[0395] FIG. 44 shows a sectional view of a stereoscopic endoscope according to a twenty-fifth embodiment of the present invention. The twenty-fifth embodiment has the insertion portion 1 and an observing portion 222. The observing portion 222 is similar to the observing portion 221 of the twenty-fourth embodiment with the adjustment mechanism 440 being attached to a holding wall 222a,and the other the common parts having the same reference numerals.

[0396] The observing portion 222 includes a pair of liquid crystal shutters 481 and 482 which are located between the two lenses of each of the imaging lenses 432cand 432d,respectively.

[0397] In the twenty-fifth embodiment, the images formed by the imaging lenses 432cand 432don the imaging device 434 are partially overlapped. Therefore, when the right image is to be formed on the imaging device 434, the left image is blocked by controlling the liquid crystal shutter 482 to be opaque. Similarly, when the left image is to be formed on the imaging device 434, the right image is blocked by controlling the liquid crystal shutter 481 to be opaque. This process results in the imaging device 434 outputting separate left and right image data. The left and right image data can then be processed by a processing device such as the processing device 100 of the first embodiment, and a three dimension image can be viewed on the monitor 190 using the pair of glasses 191.

[0398] In the twenty-first, twenty-second, twenty-fourth and twenty-fifth embodiments described above, the positioning of the separator lenses 437aand 437dcan be achieved manually. However, by adding two motors, which are similar to the first and second motors of the first embodiment, and a processing device which is similar to the processing device 100, the positioning of the separator lenses 437aand 437dcan be done automatically, in a manner similar to that described for the first embodiment. Further, in the twenty-fourth and twenty-fifth embodiments, the use of fiber bundles 439aand 439band the imaging device 434, can reduce the overall size and number of parts required to manufacture the stereoscopic endoscope. Furthermore, the reduced number of parts can improve the accuracy of the imaging provided by the stereoscopic endoscope.

[0399] Twenty-sixth Embodiment

[0400] FIG 45 shows a sectional view of a stereoscopic endoscope according to a twenty-sixth embodiment of the present invention. The twenty-sixth embodiment includes an insertion portion 1b,an extension portion 1c,and an observing portion 223. The extension portion 1cis flexible and provides a physical and optical connection between the insertion portion 1band the observing portion 223.

[0401] The insertion portion 1bis similar to the insertion portion 1 of the first embodiment. The common parts have the same reference numerals. However, separator lenses 537aand 537bare mounted in the insertion portion 1bat the location of the exit pupil.

[0402] The observing portion 223 has a first secondary optical system 530aand a second secondary optical system 530b.The first secondary optical system 530aincludes a fiber bundle 539aand an eyepiece lens 533a.The second secondary optical system 530aincludes a fiber bundle 539band an eyepiece lens 533b.A first end of each of the fiber bundles 539aand 539b,located inside the observing portion 226, is held in a fixed position. The fiber bundles 539aand 539bextend through the extension portion 1c,and into the insertion portion 1b.A second end of each of the fiber bundles 539aand 539b,located in the insertion portion 1b,is also held in a fixed position. The second ends of the fiber bundles 539aand 539bcontact the separator lenses 537aand 537b,respectively, such that the image formed by the separator lenses 537aand 537bis transmitted through the fiber bundles 539aand 539band viewed through the eyepiece lenses 533aand 533b.

[0403] As described above, since the extension portion 1cis flexible, it is possible to observe an object through a narrower opening, than is possible using only a rigid insertion portion.

[0404] Twenty-seventh Embodiment

[0405] FIG. 46 shows a sectional view of a stereoscopic endoscope according to a twenty-seventh embodiment of the present invention. The twenty-seventh embodiment includes the insertion portion 1b,the extension portion 1cand an observing portion 224.

[0406] The observing portion 224 is similar to the observing portion 223 described above. However, the eyepiece lens 533ais replaced with imaging lenses 532aand 535a,and a first liquid crystal shutter 581, and the eyepiece lens 533bis replaced with imaging lenses 532band 535b,and a second liquid crystal shutter 582. Further, images formed by the imaging lenses 532a,535a,532band 535bare detected by an imaging device 534.

[0407] In the twenty-seventh embodiment, the image formed by the imaging lenses 532a,535aand the image formed by the imaging lenses 532b,535bon the image sensing element 534 are partially overlapped.

[0408] Therefore, when the right image is to be formed on the imaging device 534, the left image is blocked by controlling the second liquid crystal shutter 582 to be opaque. Similarly, when the left image is to be formed on the imaging device 534, the right image is blocked by controlling the first liquid crystal shutter 581 to be opaque. This process results in the imaging device 534 outputting separate left and right image data. The left and right image data can then be processed by a processing device such as the processing device 100 of the first embodiment, and a three-dimensional image can be viewed on the monitor 190 using the pair of glasses 191.

[0409] Twenty-eighth embodiment

[0410] FIG. 47 shows a sectional view of a stereoscopic endoscope according to a twenty-eighth embodiment of the present invention. The twenty-eighth embodiment has the insertion portion 1aand an observing portion 225. The observing portion 225 includes the adjustment mechanism 440, described above in the twenty-first embodiment, separator lenses 637aand 637b,and imaging devices 634aand 634b.

[0411] As shown in FIG. 47, the separator lens 637aand the imaging device 634aare mounted on the support 447a.Similarly, the separator lens 637band the imaging device 634bare mounted on the support 447b.The separator lens 637areceives light from the left side of the insertion portion 1a,while the separator lens 637breceives light from the right side of the insertion portion 1a.Therefore, by rotating the first and second adjusting gears 144aand 146, the position of the separator lenses 637aand 637bin the x-axis and y-axis directions can be changed simultaneously.

[0412] The distance between the separator lenses 637aand 637bis adjusted by rotating the third adjusting gear 143a.When the third adjusting gear 143ais rotated in one direction, the lenses 637aand 637bare gradually separated, and by rotating the third adjusting gear 143ain the other direction, the lenses 637aand 637bare moved closer together.

[0413] The change of the distance between the lenses 637aand 637bvaries the distance between the viewing fields, and. therefore changes the three-dimensional effect of the image.

[0414] Twenty-ninth Embodiment

[0415] FIG. 48 shows a sectional view of a stereoscopic endoscope according to a twenty-ninth embodiment of the present invention. The twenty-ninth embodiment has an observing portion 226 and the insertion portion 1a.The observing portion 226 is similar to the observing portion 225 of the twenty-eighth embodiment described above, with common parts having the same reference numerals.

[0416] Thus, the insertion portion 1ais attached to the hood 14 and the adapter 50. The adapter 50 is then attached to a flange 226bof the observing portion 226 by passing the adjusting bolts 54 through holes 226cand securing the adjusting bolts 54 with nuts 55 and 56, in a similar manner to that described in the fifth embodiment above.

[0417] Thirtieth Embodiment

[0418] FIG. 49 shows a sectional view of a stereoscopic endoscope according to a thirtieth embodiment of the present invention. The thirtieth embodiment has an observing portion 227 and the insertion portion 1. The observing portion 227 is similar to the observing portion 226 of the twenty-ninth embodiment described above, with the common parts having the same reference numerals.

[0419] In the observing portion 227, a single imaging device 634areceives the images formed by the separator lenses 637aand 637b.Further, the observing portion 227 includes a pair of liquid crystal shutters 681 and 682 which are located between the each of the separator lenses 637aand 637b,respectively, and the imaging device 634.

[0420] In the thirtieth embodiment, the images formed by the separator lenses 637aand 637bon the imaging device 634 may be partially overlapped, in the case that the distance between the incident axes of the left and right images is small. Therefore, when the right image is to be formed on the imaging device 634, the left image is blocked by controlling the liquid crystal shutter 682 to be opaque. Similarly, when the left image is to be formed on the imaging device 634, the right image is blocked by controlling the liquid crystal shutter 681 to be opaque. This process results in the imaging device 634 outputting separate left and right image data. The left and right image data can then be processed by a processing device such as the processing device 100 of the first embodiment, and a three-dimensional image can be viewed on the monitor 190 using the pair of glasses 191.

[0421] If the adjustment device 440 increases the distance between the separator lenses 637aand 637b,then the distance between the incident axes of the left and right images is large, and the images formed on the imaging device 634 will not overlap.

[0422] Thirty-first Embodiment

[0423] FIG. 50A shows a sectional view of a stereoscopic endoscope according to a thirty-first embodiment of the present invention. The thirty-first embodiment includes the insertion portion 1 and an observing portion 228. The observing portion 228 includes a secondary optical system 630 and an adjustment mechanism 640 having a mounting frame 641 which supports the secondary optical system 630. The adjustment mechanism 640 is similar to the adjustment mechanism 40, with the common parts having the same reference numerals.

[0424] The secondary optical system 630 includes five separator lenses 637a,637b,637c,637d,and 637e,and five imaging devices 634a,634b,634c,634d,and 634e,as shown in FIG. 50B. The incident surfaces of the five separator lenses 637a,637b,637c,637d,and 637eare arranged to be coincident with the plane of the exit pupil. However, by rotating the first and second adjusting gears 44aand 46, the position of the secondary optical system 630 in the x-axis and y-axis directions can be changed simultaneously.

[0425] FIG. 50C shows the view field for each of the five separator lenses 637athrough 637e,and their corresponding imaging devices, with respect to the exit pupil Ep. As shown in FIG. 50C, by selecting an appropriate separator lens and its corresponding imaging device, the three-dimensional effect of the image can be varied.

[0426] If, for example, the output of the imaging devices 634aand 634ewere selected, then the distance between the incident axis of the left image (detected by the imaging device 634a) and the incident axis of the right image (detected by the imaging device 634e) will be a maximum. Therefore, the three-dimensional effect on the image is large. This condition is preferable for observing an object that is located at a point far way from the insertion portion 1.

[0427] Conversely, if, for example, the output of the imaging devices 634band 634dwere selected, then the distance between the incident axis of the left image (detected by the imaging device 634b) and the incident axis of the right image (detected by the imaging device 634d) will be a minimum. Therefore, the three-dimensional effect on the image is small. This condition is preferable for observing an object that is located at a point near to the insertion portion 1.

[0428] Therefore, a change in the three-dimensional effect can be achieved by selecting the appropriate pair of imaging devices in order to process the output image data. This is accomplished without the need for moving the separator lenses 637athrough 637erelative to each other.

[0429] Further, by selecting adjacent pairs of imaging devices, the output image data representative of either the left or the right image can be displayed. Thus, in order to display the left image, the imaging devices 634aand 634bshould be selected. Similarly, in order to display the right image, the imaging devices 634dand 634eshould be selected.

[0430] FIG. 51 shows a projection device 600 used to display a three-dimensional image of the object viewed in the stereoscopic endoscope. The projection device 600 includes a lenticular screen 620 and five projectors 610, 611, 612, 613 and 614 that project light beams toward the rear side of the lenticular screen 620 to form the images taken by the imaging devices 634a,634b,634c,634dand 634erespectively. The projectors are aligned along a horizontal direction Dh.

[0431] The lenticular screen 620 is composed of many parallel cylinders having generatrixes which are aligned in the vertical direction (i.e., in a direction out of the drawing). The lenticular screen 620 defines the directions of the light beams transmitted therethrough. The directions of the transmitted light beams depend on the angles of incidence of the light beams projected from the projectors 610 through 614 to the lenticular screen 620.

[0432] The light beams from each of the projectors 610 through 614 is projected onto a limited area of the lenticular screen 620. Further, the projected light beams partially overlap each other, in the horizontal direction Dh. As a result, the left and right eyes of the observer looks at the images formed by the different projectors. This forms a three-dimensional image.

[0433] Further, the observing direction changes according to a change in the view point of the observer in the horizontal direction Dh. For example, when the head H of the observer is located at the position H1, the right eye sees the image formed primarily by the second projector 611, and the left eye sees the image formed primarily by the third projector 612.

[0434] However, when the head H is moved to a position H2, the right eye sees the image formed primarily by the fourth projector 613 and the left eye sees the image formed primarily by the fifth projector 614.

[0435] Therefore by moving his head H in the horizontal direction, the observer can change his view point and see a different portion of the image.

[0436] Thirty-second Embodiment

[0437] FIG. 52 shows a sectional view of a stereoscopic endoscope according to a thirty-second embodiment of the present invention. The thirty-second embodiment includes the insertion portion 1aand an observing portion 229.

[0438] The observing portion 229 is similar to the observing portion 228 described above, with the common parts having the same reference numerals. The observing portion 229 has a base flange 229b.The base flange 229bhas an opening to allow light from the insertion portion 1ato be transmitted the observing portion 229.

[0439] Thus, the insertion portion 1ais attached to the hood and the adapter 50. The adapter 50 is then attached to e flange 229bof the observing portion 229 by passing the adjusting bolts 54 through holes 229cand securing the adjusting bolts 54 with nuts 55 and 56, in a similar manner to that described for the fifth embodiment above.

[0440] Thirty-third Embodiment

[0441] FIG. 53 shows a sectional view of a stereoscopic endoscope according to a thirty-third embodiment of the resent invention. The thirty-third embodiment includes an insertion portion 1d,the extension portion 1c,and an observing portion 230.

[0442] The insertion portion 1dis similar to the insertion portion 1, with common parts having the same reference numerals. However, the secondary optical system 630 described above, is positioned within the insertion portion 1d.Therefore, the image data output from the secondary optical system 630 is supplied to the observing unit 230, and then processed, by a processing device, such as the processing device 100 for viewing on a monitor.

[0443] Thirty-fourth Embodiment

[0444] FIG. 54 shows a sectional view of a stereoscopic endoscope according to a thirty-fourth embodiment of the present invention. The thirty-fourth embodiment includes an insertion portion 1e,the extension portion 1cand an observing portion 231.

[0445] The insertion portion 1eis similar to the insertion portion 1 shown in FIG. 1. However, five separator lenses 737a,737b,737c,737dand 737eare attached to the insertion-portion 1e,such that an incident surface of each of the separator lenses 737athrough 737eis coincident with a plane of the exit pupil.

[0446] Five first ends of five fiber bundles 739a,739b,739c,739dand 739eare attached to the insertion portion 1e,such that each of the first ends contacts a corresponding one of the five separator lenses 737athrough 737e.The fiber bundles 739athrough 739etransmit the images formed by the separator lenses 737athrough 737eto the observing unit 231.

[0447] The observing unit 231 includes imaging lenses 732a,732b,732c,732dand 732e,and imaging devices 734a,734b,734c,734dand 734e.The imaging devices 732athrough 732ereceive light from the fiber bundles 739athrough 739e,respectively, and form an image on the imaging devices 734athrough 734e,respectively. Image data is output from imaging devices 734athrough 734eto a processing device, such as the processing device 100, where a three-dimensional of the image is generated and viewed through a monitor.

[0448] Thirty-fifth Embodiment

[0449] FIG. 55 shows a sectional view of a stereoscopic endoscope according to a thirty-fifth embodiment of the present invention. The thirty-fifth embodiment includes the insertion portion 1e,the extension portion 1cand an observing portion 232.

[0450] The observing portion 232 is similar to the observing portion 231 described above. However, only the three central separator lenses 732b,732cand 732dand corresponding imaging devices 734b,734cand 734dare used.

[0451] The images transmitted by the two fiber bundles 739band 739dare observed by the observer using eyepiece lenses 733aand 733b.Therefore, direct viewing of a three-dimensional image is possible through the eyepiece lenses 733aand 733b.Further, the image signal output by the three imaging devices 734b,734cand 734dmay be processed and viewed on an external monitor.

[0452] Thirty-sixth Embodiment

[0453] FIG. 56A shows a sectional view of a stereoscopic endoscope according to a thirty-sixth embodiment of the present invention. The thirty-sixth embodiment includes the insertion portion 1e,the extension portion 1cand an observing portion 233.

[0454] The observing portion 233 is similar to the observing portion 232 described above. However, as shown in FIGS. 56A and 56B, the image formed by each of the imaging lenses 732band 732dis incident on half-mirrors 780aand 780b,respectively.

[0455] The half-mirror 780atransmits half of the light to the eyepiece lens 733a,and reflects the other half of the light to the imaging device 734bthrough an imaging lens 732f.Similarly, the half-mirrors 780btransmits half of the light to the eyepiece lens 733b,and reflects the other half of the light to the imaging device 734dthrough an imaging lens 732g.

[0456] With the above construction, the image can be viewed directly through the eyepiece lenses 733aand 733b.Further, all five imaging devices can output image data to a processing device such as the processing device 100.

[0457] Thirty-seventh embodiment

[0458] FIG. 57 shows a sectional view of a stereoscopic endoscope according to a thirty-seventh embodiment of the present invention. The thirty-seventh embodiment includes the insertion portion 1 and an observing portion 234.

[0459] The observing portion 234 is similar to the observing portion 230 and includes an adjustment mechanism 840 which is similar to the adjustment mechanism 440 shown in FIG. 47, with the common parts having the same reference numerals. The adjustment mechanism is attached to the wall 234aof the observing mechanism 234.

[0460] The observing portion 234 also includes three separator lenses 837a,837band 837cfor forming images on three corresponding imaging devices 838a,838band 838c,in a similar manner to that described above for the previous embodiments.

[0461] The separator lens 837aand the imaging device 838aare attached to support 847a,while the separator lens 837band the imaging device 838bare attached to support 847b.The separator lens 837cand the imaging device 838care attached to the holding frame 841.

[0462] The distance between the separator lenses 837aand 837bis adjusted by rotating the third adjusting gear 143a.Therefore, the three-dimensional effect of image can be varied, as described before. Further, by adjusting screws 144aand 146, the position of the separator lens—imaging device combinations in the x-axis and y-axis directions can be changed simultaneously.

[0463] FIGS. 58A, 58B and 58C show the locations of the separator lenses 837a,837band 837cin the exit pupil of the primary optical system 10. FIG. 58A shows the condition where the separator lenses 837a,837band 837care located closest to each other (i.e., contacting each other). FIG. 58B shows the condition where the separator lenses 837a,837band 837care located at their maximum distance apart.

[0464] FIG. 58C shows the condition in which the separator lenses 837a,837band 837care closest together, but located on one side of the exit pupil. This can be achieved by rotating the adjusting gear 144ain order to move the holding frame 141 in the y-axis direction.

[0465] An alternative to the thirty-seventh embodiment uses separator lenses which are designed such that the sum of the diameters of the lenses is equal to the diameter of the exit pupil Ep, as shown in FIG. 58D.

[0466] FIGS. 59A through 59D show variations of the arrangement of the separator lenses in the exit pupil Ep. A two dimensional arrangement allows a change in the direction of parallax according to which pair of separator lenses are selected.

[0467] If the three separator lenses 837a,837b,837care arranged at vertexes of a triangle as shown in FIG. 59A, one of the three different directions d1, d2 and d3 can be selected as the direction of parallax.

[0468] Further, in case four separator lenses (i.e., 837a,837b,837c,and 837d) are arranged at ends of a cross as shown in FIG. 59B, one of the two different directions dv and dh can be selected as the direction of parallax.

[0469] More separator lenses (such as 837eand 837f) may be arranged as shown in FIGS. 59C and 59D. These two dimensional arrangements of the separator lenses permit a change in the observation direction without changing the direction and/or the angle of the primary optical system 10.

[0470] The thirty-eighth through forty-seventh embodiments will be described with reference to FIGS. 60 through 70. In these embodiments, refracting prisms are used in the pupil dividing mechanism.

[0471] Thirty-eighth Embodiment

[0472] FIG. 60 shows a sectional view of a stereoscopic endoscope according to a thirty-eighth embodiment of the present invention. The thirty-eighth embodiment includes the insertion portion 1 and an observing portion 235.

[0473] The observing portion 235 includes a first secondary optical system 930a,a second optical system 930b,a first prism 970 and a second prism 971. The first prism 970 and the second prism 971 divide the light beam at the exit pupil, into two light beams. One of the divided light beams is refracted towards the first secondary optical system 930aby the first prism 970, while the other light beam is refracted towards the second secondary optical system 930bby the second prism 971.

[0474] The first secondary optical system 930ahas an imaging lens 932awhich receives light from the first prism 970 and forms an image of the object on an imaging device 934a.Similarly, the second secondary optical system 930bhas an imaging lens 932bwhich receives light from the second prism 971 and forms an image of the object on an imaging device 934b.

[0475] The first prism 970 and the second prism 971 are wedge-shaped and contact each other at their respective apexes, as shown in FIG. 60. Further, the first prism 970 and the second prism 971 are located in a plane coincident with the exit pupil.

[0476] The first prism 970 consists of two prisms 970aand 970bbonded together. Each of the two prisms 970aand 970bhas a different refractive index, in order to reduce chromatic aberrations. Similarly, the second prism consists of two prisms 971aand 971b,which have different refractive indexes, bonded together.

[0477] The prisms 970a,970b,971a,and 971bmust satisfy the below noted equations 1 and 2 in order to cancel the chromatic aberration. In equations 1 and 2, “A1” and “A2” denote apex angles of the prisms 970a,970b,971a,and 971b,“V1” and “V2” denote Abbe numbers, “N1” and “N2” denote refractive indexes and “Dt” denotes a composed deviation angle of the two prisms. $\begin{array}{cc}\mathrm{A1}=\frac{\mathrm{Dt}\times \mathrm{V1}}{\left(\mathrm{N1}-1\right)\times \left(\mathrm{V1}-\mathrm{V2}\right)}& \left(1\right)\\ \mathrm{A2}=\frac{\mathrm{Dt}\times \mathrm{V2}}{\left(\mathrm{N2}-1\right)\times \left(\mathrm{V2}-\mathrm{V1}\right)}& \left(2\right)\end{array}$

[0478] If equations 1 and 2 are satisfied, then the prisms 970a,970b,971a,and 971bwill be achromatic

[0479] The picture data output from the imaging devices 934aand 934bare processed by a processing device, such as processing device 100, in order to display a three-dimensional picture on a monitor.

[0480] Further, the images formed on the imaging devices 934aand 934binclude trapezoid distortion due to refraction by the prisms 970, 971. The distortion of the image may be canceled by the well-known affine transformation process

[0481] As described above, the angle between the light beams refracted by each of the prisms 970 and 971 can be minimized. Further, since imaging devices are employed, the secondary optical systems do not have to be parallel. Therefore, the size of the observing portion can be reduced. Furthermore, the number of parts required to construct each of the secondary optical systems can be reduced, since mirrors etc. are not required. This also improves the accuracy of aligning the optical elements used in the observing unit 235.

[0482] Thirty-ninth Embodiment

[0483] FIG. 61 shows a sectional view of a stereoscopic endoscope according to a thirty-ninth embodiment of the present invention. The thirty-ninth embodiment includes the insertion portion 1aand an observing portion 236.

[0484] The observing portion 236 is similar to the observing portion 235 described above, with common parts having the same reference numerals. The observing portion 236 has a base flange 236b.The base flange 236bhas an opening to allow light from the insertion portion 1ato be transmitted to the observing portion 236. Thus, the insertion portion 1ais attached to the hood 14 and the adapter 50. The adapter 50 is then attached to the flange 236bof the observing portion 236 by passing the adjusting bolts 54 through holes 236cand securing the adjusting bolts 54 with nuts 55 and 56, in a similar manner to that described for the fifth embodiment above.

[0485] Fortieth Embodiment

[0486] FIG. 62 shows a sectional view of a stereoscopic endoscope according to a fortieth embodiment of the present invention. The fortieth embodiment includes the insertion portion 1 and an observing portion 237.

[0487] The observing portion 237 is similar to the observing portion 235 described above in the thirty-eighth embodiment, with common parts having the same reference numerals. In the observing portion 237, the first prism 970 is separated from the second prism 971 by a shading plate 925. This results in the distance between the incident axes of the first and second light beams being separated. This will increase the three-dimensional effect of the image detected by the imaging devices 934aand 934b,in a manner similar to that described for the previous embodiments.

[0488] FIG. 63 shows a modification of the arrangement of the first prism 970, the second prism 971 and the shading plate 925. shown in the fortieth embodiment. In this modification, the first prism 970 contacts the second prism 971 at the apex. However, the shading plate 925 is positioned to block light incident on an area of the two prisms 970 and 971 around the point where the prisms contact each other.

[0489] Forty-first Embodiment

[0490] FIG. 64 shows a sectional view of a stereoscopic endoscope according to a forty-first embodiment of the present invention. The forty-first embodiment includes the insertion portion 1 and an observing portion 238.

[0491] The observing portion 238 allows direct viewing of a three-dimensional image of the object. The observing portion has a first secondary optical system 940a,a second secondary optical system 940b,a first prism 973 and a second prism 974.

[0492] The first secondary optical system 940aincludes the imaging lens 932a,an eyepiece lens 933a,and a deflecting prism 972a.Similarly, the secondary optical system 940bincludes the imaging lens 932b,an eyepiece lens 933b,and a deflecting prism 972b.

[0493] The first prism 973 and the second prism 974 are arranged to contact each other at their respective apexes, in a similar manner to that described for the prisms 970 and 971, in the thirty-eighth embodiment.

[0494] The light beams refracted by each of the prisms 970 and 971, are refracted by the prisms 972aand 972b,such that the refracted light beams are made parallel to the optical axis Ax1, towards the imaging lenses 932aand 932b.The lenses 932aand 932bform left and right images which are viewed using the eyepiece lenses 933aand 933b,respectively.

[0495] In the forty-first embodiment, the first prism 973 and the second prism 974 are not formed of separate prisms bonded together, since the chromatic aberrations of the prisms 973 and 974 will be canceled by the chromatic aberrations of the deflecting prisms 972aand 972b.Further, there is no trapezoidal distortion of the image viewed through the eyepiece lenses 933aand 933band therefore the affine transformation is not required.

[0496] Forty-second Embodiment

[0497] FIG. 65 shows a sectional view of a stereoscopic endoscope according to a forty-second embodiment of the present invention. The forty-second embodiment includes the insertion portion 1aand an observing portion 239.

[0498] The observing portion 239 is similar to the observing portion 238 described above, with common parts having the same reference numerals. The observing portion 239 has a base flange 239b.The base flange 239bhas an opening to allow light from the insertion portion 1ato be transmitted to the observing portion 239. The insertion portion 1ais attached to the hood 14. The hood 14 is securely fastened to the adapter 50, and the adapter 50 is attached to the base flange 239b,in a similar manner to that described for the fifth embodiment above.

[0499] Forty-third Embodiment

[0500] FIG. 66 shows a sectional view of a stereoscopic endoscope according to a forty-third embodiment of the present invention. The forty-third embodiment includes the insertion portion 1 and an observing portion 240.

[0501] The observing portion 240 has a first secondary optical system 941a,a second secondary optical system 941b,the first prism 973 and the second prism 974.

[0502] The first secondary optical system 941aincludes the deflecting prism 972aand the imaging lens 932awhich forms a left image on a portion of an imaging device 934c.Similarly, the secondary optical system 940bincludes the deflecting prism 972b,and the imaging lens 932bwhich forms a right image on another portion of the imaging device 934c.

[0503] The left and right images that are formed on separate areas of the imaging device 934cdo not overlap. Therefore, the image data that is output by the imaging device 934ccan be processed by a processing device such as the processing device 100, and separated into left image data and right image data. Then, by alternately displaying the left and right images on the monitor 190 and wearing the pair of glasses 191, an observer can view a three-dimensional image.

[0504] Forty-fourth Embodiment

[0505] FIG. 67 shows a sectional view of a stereoscopic endoscope according to a forty-fourth embodiment of the present invention. The forty-fourth embodiment includes the insertion portion 1 and an observing portion 241.

[0506] The observing portion 241 has a first secondary optical system 942a,a second secondary optical system 942b,the first prism 973 and the second prism 974, a half mirror prism 980, a first liquid crystal shutter 981, a second liquid crystal shutter 982, and an imaging device 934a.

[0507] The first secondary optical system 942aincludes a deflecting prism 972c,an imaging lens 932c,and a mirror 931a.Similarly, the secondary optical system 942bincludes a deflecting prism 972d,an imaging lens 932d,and a mirror 931b.The imaging lenses 932cand 932dhave a different shape than the imaging lenses 932aand 932b,since the distance between the imaging lenses 932cand 932dand the imaging device 934ais longer than the distance between the imaging lenses 932aand 932band the imaging device 934c.

[0508] The deflecting prisms 972cand 972dhave the same function as the prisms 972aand 972b,of the previous embodiments, however the shape of the prisms 972cand 972dis slightly different than the shape of the prisms 972aand 972bin order to accommodate the change in the shape of the imaging lenses 932cand 932d,respectively.

[0509] Thus, light which enters the exit pupil of the insertion portion 1 is split by the prisms 973 and 974 and refracted to the optical systems 942aand 942b.The light which is transmitted by the optical system 942ais reflected by the mirror 931a,through the liquid crystal shutter 981 to be incident on the half mirror prism 980. Half of the light is reflected by the half mirror prism 980 towards the imaging device 934a,where the left image is detected and the left image data is output. When the left image data is being detected, the shutter 982 is made opaque, thereby blocking the right image from interfering with the left image.

[0510] Similarly, the light which is transmitted by the optical system 942bis reflected by the mirror 931b,through the liquid crystal shutter 982 to be incident on the half mirror prism 980. Half of the light is reflected by the half mirror prism 980 towards the imaging device 934a,where the right image is detected and the right image data is output. Further, when the right image data is being detected, the shutter 981 is made opaque, thereby blocking the left image from interfering with the right image.

[0511] The left and right images are formed on overlapping portions of the imaging device 934a.Therefore, by controlling the shutters 982 and 981 to be alternately opaque and transparent, the left and right image data can be detected by the imaging device 934aand output to a processing device, such as the processing device 100, for viewing on a monitor using the pair of glasses 191.

[0512] As described above, the imaging device 934ais half the size of the imaging device 934c.Therefore, the cost of manufacturing the stereoscopic endoscope can be reduced.

[0513] Forty-fifth Embodiment

[0514] FIG. 68 shows a first secondary optical system 943a,a second secondary optical system 943b,and a roof prism 975 of an observing portion 242, and an imaging lens 13 of the insertion portion 1 of a stereoscopic endoscope according to a forty-fifth embodiment of the present invention.

[0515] As shown in FIG. 68, the thickness of the roof prism 975 is a maximum at the center thereof, and gradually decreases towards each end. The roof prism 975 has two incident surfaces 975aand 975b.Light which is incident on the incident surface 975ais refracted towards the first secondary optical system 943a,thereby forming an image on the imaging device 934a.Similarly, light which is incident on the incident surface 975bis refracted towards the second secondary optical system 943b,thereby forming an image on the imaging device 934b.

[0516] The refraction of the light by the roof prism 975 introduces a trapezoidal distortion into the images formed on the imaging devices 934aand 934b.Therefore, the image data output by the imaging devices 934aand 934bshould be processed with the affine transform in order to remove the trapezoidal distortion. Further, by processing with the processing device 100, a three-dimensional image may be viewed on the monitor 190 using the pair of glasses 191.

[0517] Forty-sixth Embodiment

[0518] FIG. 69 shows an observing portion 243, and an imaging lens 13 of the insertion portion 1 of a stereoscopic endoscope according to a forty-sixth embodiment of the present invention.

[0519] The observing portion 243 is similar to the observing portion 242 described above, with common parts having the same reference numerals. The observing portion 219 includes a deflecting prism 976 located between the first and second secondary optical systems 943aand 943band the roof prism 975. The apex of the deflecting prism 976 has the same angle as the apex of the roof prism 975 Therefore, the chromatic aberrations and trapezoidal distortion introduced into the light beams refracted by the roof prism 975 is canceled by the deflecting prism 976. The left and right images detected by the imaging devices 934aand 934b,can be processed normally using the processing device 100, and a three-dimensional image can be viewed on the monitor 190 using the pair of glasses 191.

[0520] Forty-seventh Embodiment

[0521] FIG. 70 shows a sectional view of a stereoscopic endoscope according to a forty-seventh embodiment of the present invention. The forty-seventh embodiment includes the insertion portion 1 and an observing portion 244.

[0522] The observing portion 244 has a first secondary optical system 944a,a second secondary optical system 944b,the roof prism 975 and the deflecting prism 976, the half mirror prism 980, the first liquid crystal shutter 981, the second liquid crystal shutter 982, and the imaging device 934d.

[0523] The first secondary optical system 944aincludes the imaging lens 932aand the mirror 931a.Similarly, the secondary optical system 944bincludes the imaging lens 932band the mirror 931b.

[0524] Thus, light which enters the exit pupil of the insertion portion 1 is split by the roof prism 975 and refracted by the deflecting prism 976 and to the optical systems 944aand 944b.The light which is transmitted by the optical system 944ais reflected by the mirror 931a,through the liquid crystal shutter 981 to be incident on the half mirror prism 980. Half of the light is reflected by the half mirror prism 980 towards the imaging device 934d,where the left image is detected and the left image data is output. When the left image data is being detected, the shutter 982 is made opaque, thereby blocking the right image from interfering with the left image.

[0525] Similarly, the light which is transmitted by the optical system 944bis reflected by the mirror 931b,through the liquid crystal shutter 982 to be incident on the half mirror prism 980. Half of the light is reflected by the half mirror prism 980 towards the imaging device 934d,where the right image is detected and the right image data is output. Further, when the right image data is being detected, the shutter 981 is made opaque, thereby blocking the left image from interfering with the right image.

[0526] The left and right images are formed on overlapping portions of the imaging device 934d.Therefore, by controlling the shutters 982 and 981 to be alternately opaque and transparent, the left and right image data can be detected by the imaging device 934dand output to a processing device, such as the processing device 100, for viewing on a monitor using the pair of glasses 191.

[0527] As described above, the imaging device 934dis half the size of the imaging device 934c.Therefore, the cost of the stereoscopic endoscope can be reduced.

[0528] The present disclosure relates to subject matter contained in Japanese patent application Nos. Hei 6-319300 (filed on Nov. 29, 1994), Hei 6-331229 (filed on Dec. 8, 1994), Hei 6-340053 (filed on Dec. 28, 1994), Hei 6-340055 (filed on Dec. 28, 1994), Hei 7-44779 (filed on Feb. 9, 1995), Hei 7-50613 (filed on Feb. 15, 1995), Hei 7-61749 (filed on Feb. 24, 1995), Hei 7-136043 (filed on May 10, 1995) and Hei 7-191143 (filed on Jul. 4, 1995) which are expressly incorporated herein by references in their entireties.