Kit for Converting a Standard Microscope Into a Single Aperture Confocal Scanning Epi-Illumination Microscope

FIG. 1 is a diagrammatic view of the single aperture confocal scanning epi-illumination microscope formed by installation of the kit of the present invention to a regular epi-illumination microscope;

FIG. 2 is a partial view of the optics portion of the microscope with light rays drawn in to represent the incident light;

FIG. 3 is a partial view of the optics of the microscope with light rays drawn in to represent the returning light;

FIG. 4 is a diagrammatic view of the optics of the second embodiment of the present invention utilizing mirrors to relocate the conjugate field plane out of the vertical optical axis of the microscope;

FIG. 5 is a side view of a version of the kit installed on a standard microscope;

FIG. 6 is a cross-sectional view taken along the plane of line 6--6 in FIG. 5 showing the interchangeable lens;

FIG. 7 is a cross-sectional view taken along the plane of line 7--7 in FIG. 5 detailing the aperture with the wedge-shaped slots;

FIG. 8 is a diagrammatic view of the optics of the third embodiment of the present invention utilizing only one extra standard objective lens positioned at its correct tube length; and

FIG. 9 is a diagrammatic view of the optics for two alternate versions of the third embodiment showing either a standard or specially ground objective lens placed relatively closer to the aperture.

As best shown in FIG. 1, the first embodiment of the kit as installed on a standard epi-illumination microscope results in the single aperture confocal scanning epi-illumination microscope 20. As shown therein, a light source 22 produces a beam of incident light 24 for illuminating the specimen. A beam splitter such as a half-silvered mirror or the like 26 reflects the incident light 24 through a first, standard objective, intermediate lens 28 which focuses the incident light at a first field plane where an aperture 30 is positioned. The aperture 30 may comprise a single pin hole or spot, a rectangular slit, an Archimedian spiral of holes, or any other suitable aperture as is known in the art of confocal scanning microscopes. A second intermediate lens 32, which may also be a standard objective lens, defocuses the incident light into the standard objective lens 34 of the microscope 20. A negative or diverging lens 36 may be placed between lenses 32, 34 to correct for the tube lengths of lenses 32 and 34, as is known in the art. The inventors have utilized matched 10x, EF, 160 mm standard objective lenses for lenses 28, 32. It is noted that lenses 28, 32 are utilized to create the field plane at aperture 30 for both incident light and light returning from the specimen 38 mounted on the stage 40. Thus, both incident and reflected light traverse lenses 28, 32. If the lenses 28, 32 are matched, there is greater assurance that the same effect is given to the light as it passes through both lenses. However, excellent images may be obtained with a simple plano-convex lens replacing lens 32. Furthermore, the magnification of the microscope 20 may be changed by merely replacing lens 28 with a lens having a different power. This is because both incident and reflected light traverse lens 28, and lens 2B is "above" the aperture and specimen. A means to move the aperture 30 (rotating Nipkow disc, slits, or spots) is included. If a rectilinear scan of a pinhole aperture is desired, an X-Y stage controller 42 and matched computer 44 which are well known in the art for controlling the movement of a microscope stage could serve. The inventors have found that such a controller may also be used for controlling the movement of aperture 30 within the conjugate field plane to achieve the scanning of the aperture across the specimen 38 as desired herein. A second half-silvered mirror or the like 46 may be utilized to divert the reflected light either into an eyepiece 48 for direct viewing of the specimen 38, or for directing the light to video camera 50 which produces a plurality of images reconstructed by an image processor 52 for display on a CRT 54 or the like.

In practice, the inventors have found that the X-Y stage controller 42 may be a part No. 517MF as manufactured by Stahl Research Laboratories, and that the aperture may be mounted to a 22 mm stage as manufactured by Artek. Also, a light source producing blue, green, or ultraviolet light may be utilized for light source 22, and the specimen 38 may be dyed such that incident light impinging on specimen 38 induces fluorescence of a different wavelength to facilitate its separation from incident light by standard fluorescence excitation and barrier filters near the half-silvered or dichroic mirror 26. However, it is to be understood that these particular components are merely examples of those which might be utilized by one of ordinary skill in the art and that other equivalent devices for achieving separation of incident from reflected light may also be used without departing from the spirit and scope of the invention. For example, bright field epi-illumination may also be carried out with an aperture in a surface that does not reflect light into the ocular or whose reflections are blocked by cross polarization.

As shown in FIG. 1, those items which comprise the kit for converting the ordinary microscope into the single aperture confocal scanning microscope 20 include intermediate, standard objective lenses 2B, 32; aperture 30; X-Y stage controller 42; and computer 44. As an option, the negative or diverging lens 36 may also be included to correct for the tube length of lenses 32, 34, as mentioned above. Typically, a standard, laboratory use, epi-illumination microscope would include the other components as shown in FIG. 1. The mechanical positioning and layout of a commercial embodiment of the kit 21 as installed on an ordinary microscope is more fully explained below and shown in FIG. 5.

As best shown in FIGS. 2 and 3, a conjugate field plane for both incident and returning light is created as it traverses the space between the mirror 26 and the specimen by lenses 28, 32, both of which are in the light paths for incident and reflected light. This is more easily understood by referring first to FIG. 2 which represents the incident light. Typically, a light source 22 includes a lamp 56 for creating the illumination, a first lens 58 and second lens 60 which accommodate the placement of an aperture diaphragm 62 for adjusting the intensity of the incident light and also creating a field plane for the placement of a field diaphragm 64 to permit adjustment of the incident light beam size. A third lens 62 provides further control for focusing the incident light. As mentioned, these components are typically included within a Kohler illumination type light source 22, as known in the art. The incident light is then reflected by half-silvered or dichroic mirror 26 through the first intermediate lens 28 which creates a field plane 66 of the incident light for insertion of the aperture. This field plane 66 is conjugate to the field plane created at the specimen, or specimen plane 68. Field plane 64 is also conjugate to field plane 66. This minimizes the potential for inadvertent misalignment of the light source such that a good quality illuminating beam is formed.

As best shown in FIG. 3, the image forming path of the returning light essentially retraces the same path as the incident light traversed between the mirror 26 and specimen plane 68. However, the intermediate lens 32 acts to refocus the returning light and induce a field plane 70 which is conjugate to the specimen plane 6B. It is noted that the induced conjugate field plane 70 for the returning light is coincident with the induced conjugate field plane 66 of the incident light such that an aperture placed at this coincident conjugate field plane has the same effect upon the incident light as it does upon the returning light. Additionally, another conjugate field plane 72 is induced such that an eyepiece 48 may be used to replicate the magnified specimen at the viewer's eye, or a video camera or film (see FIG. 1) may be used to replicate the specimen as necessary to record an image.

As shown in FIG. 4, a microscope arrangement 74 can be formed by adding to the kit 21 a first pair of mirrors 76, 78 which are placed at an acute angle in the light path for both incident and reflected light. These mirrors reflect the light out of the optical axis or centerline 80 of the microscope 74 and through the intermediate lenses 28, 32. A second pair of mirrors 82, 84 are then used to bounce the incident and reflected light back in alignment to create the conjugate field plane 66, 70 at a point physically removed from the optical axis of centerline 80. As is well known to those in the art, the angles at which mirrors 76, 78, 82, 84 are positioned are virtually limitless and can be used to greatly vary the distance between mirrors 82, 84 and thereby increase the physical accessibility to the conjugate field planes 66, 70, as desired. Also, the lateral distance between the conjugate field planes 66, 70 and the optical axis or centerline BU may be changed as desired.

As shown in FIGS. 5, 6, and 7, an embodiment of the kit 21 is attached to the nosepiece 86 of a standard epi-illumination microscope with the microscope's standard objective lens 88 being secured to the kit 21. Therefore, the kit 21 interfits between the nosepiece B6 and the standard objective lens 88 in the manner shown. The kit 21 includes a generally elongated assembly 90 having a first pair of mirrors 92, 94 which divert the incident and reflected light along the length of the assembly 90. A second pair of mirrors 96, 98 direct the incident and reflected light through a spinning aperture 100 which takes the form of a circular disc having a number of wedge shaped, radially aligned slits 102, 104. The aperture 100 is rotated by motor 106 and controlled by motor control 10S. At a midpoint in the assembly 90 is mounted a lower fixed lens 110 and an upper rotatable wheel 112 (see FIG. 6) having four separate lenses 114, 116, 11B, 120; any one of which may be rotated into position in the light path. Lens 110 corresponds to lens 28 and lenses 114-120 correspond to lens 32 in FIG. 1 and perform a like function as explained above. Changing lenses with rotatable wheel 112 achieves a change in magnification and illumination of the specimen. A mechanical positioning device 122 mounted atop the outboard end of assembly 90 permits repositioning of the aperture 100 with respect to mirrors 96, 98. This permits adjustment of the optical sectioning viewed by the microscope as the average width of apertures 102, 104 (see FIG. 7) through which the light traverses is changed due to their wedge shape, thereby changing the size of the scanning light beam. The smaller the width of the apertures 102, 104 used to mask the incident and reflected light, the smaller the depth of the optical section obtained.

Still another embodiment of the invention disclosed and claimed herein is shown in FIG. 8 and includes a standard eyepiece 124, a beam splitter 126, a standard objective lens 128, an aperture means 130, a second standard objective lens 132, and a specimen plane 134. Other components of the standard microscope are not shown in FIG. 8 for purposes of clarity. As noted previously herein, each standard objective lens 128, 132 has a tube length representing the distance between the back focal plane 136, 138 respectively at each of lenses 128, 132 and its focal plane 140, 142 wherein a color corrected image is formed. As shown in FIG. 5, this requires a physical separation represented by arrows 144, 146 corresponding to mounting tubes which may, in some instances, render the resulting microscope unwieldy or inconvenient for use. However, a major advantage can be realized in the embodiment in FIG. 8 in that only a single extra standard objective lens 128 is required to create the field plane at aperture 130 both for incident light, and reflected light as the standard objective lens 132 need not be paired with the second intermediate lens, such as lens 32 as shown in FIG. 1 in order to correct for the tube length. For purposes of illustration, arrows 148 and 150 represent the working distances for the standard objective lenses 12B, 132. The full rated working distance of each of these lenses 128, 132 can be realized as the geometry of the microscope is arranged to make use of the full tube length rating of each lens.

An alternate version of the embodiment shown in FIG. 8 is shown in FIG. 9 and includes the same lens 124, 128 and beam splitter 126 along with aperture 130 all oriented in their same relative physical positions. However, lens 152 may be either a standard objective lens or a specially ground lens, either one of which is oriented physically closer to the aperture 130 to render the microscope more compact and more readily usable in a manner similar to other standard microscopes presently commercially available. If lens 152 is a standard objective lens, then, as explained above, color aberrations may be induced in the resultant image and a reduced working height, as represented by the distance between arrows 154, may be experienced with the risk that the working height is reduced to a dimension so small as to render the microscope virtually unusable for many applications.

If lens 152 is a specially designed and manufactured lens having a reduced tube length, then the working distance and color aberration problems may be overcome with some sacrifice in the versatility of the microscope in that lens 152 may not be interchanged with other standard objective lenses.

There are various changes and modifications which may be made to the invention as would be apparent to those skilled in the art. However, these changes or modifications are included in the teaching of the disclosure, and it is intended that the invention be limited only by the scope of the claims appended hereto.