Background of the Invention
The invention relates to optical instruments, specifically to conical-lens microscopes.
Multiple magnification is a new concept in optics which was introduced and first published in U.S. Pat. No. 4,277,148, Conical Split-Image Microscopic Lens, dated July 7, 1981, Inventor: John E. Clegg.
Summary of the Invention
Conical-lens microscopes have a number of advantages over spherical-lens microscopes. There is no focusing; therefore there is no need of a rack and pinion. High fixed working distance between lens and object is possible. There is no turret with mounted achromatic objectives, nor are there separate eyepieces which must be interchanged; instead, the conical lenses and a single eyepiece are mounted inside the microscopic tube, protected from dust, moisture and wear. Conical surfaces are easier to calculate, measure and grind than spherical surfaces. Finally, extremely high magnification is possible, and the clarity and resolution of images is superior to that of spherical-lens microscopes. While it is true that light rays must pass through six separate surfaces of the conical lens for each stage used, and that a certain amount of interference will occur, the interference will be minor when compared to the interference produced at the focal point of high-powered spherical lenses. Images produced by conical lenses will be essentially distortion-free.
A major disadvantage of the conical-lens microscope is that each stage is formed of three component lenses, with a total of six sections (faces) for each stage. The four-stage microscope has a total twenty-four sections, and the eight-stage microscope has twice that number. Production costs would be prohibitive were it not for the savings resulting from the elimination of the rack and pinion, turret, three achromatic lenses, and three separate mounted eyepieces. Also, the use of quadrant lenses will mean that only one whole lens will have to be ground for the four-stage microscope and only two whole lenses for the eight-stage microscope.
Description of the Drawings
FIG. 1 is a longitudinal section of a conical stage lens.
FIG. 2 is a cross section of a blank component lens formed of four quadrants prior to grinding.
FIG. 3 is an elevation of a double-tube eight-stage microscope.
FIG. 4 is a cross section taken on line 4--4 of FIG. 3.
Description of the Preferred Embodiment
FIG. 1 is a longitudinal section of a stage lens 1 consisting of three component lenses; lower component lens 2 with concave conical section 3 and convex conical section 4, middle component lens 5 with convex conical section 6 and concave conical section 7, and upper component lens 8 with concave conical section 9 and planar section 10.
FIG. 2 is a cross section of a blank component lens consisting of four blank quadrants which are cemented together prior to grinding. After being ground and polished, the quadrant lenses are separated, enclosed in metal jackets and mounted in the microscopic tube.
FIG. 3 is a view of an eight-stage quadrant microscope with six visible quadrant stage lenses 11-16 and two quadrant stage lenses 17-18 rotated out of view. Each quadrant stage lens 11-18 consists of three quadrant component lenses; lower quadrant component lens 19 with quadrant concave conical section 20 and quadrant convex conical section 21, middle quadrant component lens 22 with quadrant convex conical section 23 and quadrant concave conical section 24, and upper quadrant component lens 25 with quadrant concave conical section 26 and quadrant planar section 27.
Each quadrant stage lens 11-18 is assembled from lower, middle and upper quadrant component lenses 19, 22 and 25. Each quadrant stage lens 11-18 has a cylindrical wall 28, two plane longitudinal walls 29 extending inward from cylindrical wall 28 to the common axis of the quadrant stage lenses 11-18, where the two plane longitudinal walls 29 abut at an angle of 90.degree., and two basal end walls 30 located at opposite ends of each quadrant stage lens 11-18.
Each quadrant stage lens 11-18 is mounted in a tubular metal jacket 31, with the inner tubular wall 32 being of the same degree of curvature as cylindrical wall 28, with two plane longitudinal walls 33 enclosing portions of plane longitudinal walls 29, and with two basal end walls 34 enclosing portions of basal end walls 30.
Quadrant stage lenses 11-18 and their jackets 31 are mounted vertically in a single microscopic tube or in a double microscopic tube 35 formed of two adjoined single tubes with the intervening walls removed, as shown in FIGS. 3 and 4. There is a circular slot 36 in the double tube 35 at each level in which a quadrant stage lens 11-18 and its jacket 31 are mounted. Shanks 37 engage jackets 31 and extend laterally through slots 36 to rotating knobs 38, which are the means of rotating quadrant stage lenses 11-18 into and out of the line of vision from outside the double tube 35. The tubular portions 39 of jackets 31 form arcs greater than 180.degree. so as to rotate around the axis of the quadrant stage lenses 11-18 and the central axis of double tube 35.
In operation, parallel rays 40 from the object pass through optical window 41 mounted in lower housing 42 and are refracted by quadrant conical sections 20, 21, 23, 24 and 26 of quadrant stage lens 11. The 1st enlarged image 43 (5.times.) is emitted by quadrant planar section 27. One fifth of 1st enlarged image 43 is received by quadrant conical section 20 of quadrant stage lens 12, which produces 2nd enlarged image 44 (25.times.). The 3rd enlarged image 45 (125.times.) produced by quadrant stage lens 13 is shown in cross section in FIG. 4.
The 4th enlarged image 46 (625.times.) is produced by quadrant stage lens 14 and is reflected from the top of double tube 35 to the bottom thereof by upper mirrors 47 mounted in upper housing 48. Reflected image 49 is reflected up into quadrant stage lens 15 by lower mirrors 50 mounted in lower housing 42. Quadrant stage lens 15 produces 5th enlarged image 51 (3125.times.), and quadrant stage lens 16 produces 6th enlarged image 52 (15,625.times.), which is shown in FIGS. 3 and 4.
Quadrant stage lenses 17 and 18 are rotated out of the line of vision, so 6th enlarged image 52 is received by eyepiece lens 53 which produces 7th enlarged image (78,125.times.) (not shown).
The apexes of quadrant concave conical sections 20 of lower quadrant component lenses 19 are critical areas in so far as grinding is concerned, and these areas should be avoided when producing multiple magnification. Tubular shims 0.5 mm thick should be placed between quadrant stages 11-13 and 15-17 and jackets 31 to move the apex areas out of the line of vision. Three shims should be placed between quadrant stage lens 11 and its jacket 31, two shims between quadrant stage lens 12 and its jacket 31, and one shim between quadrant stage lens 13 and its jacket 31. The same numbers of shims should be placed between quadrant stages 15-17 and their jackets 31. Other parts will have to be modified to reflect these design changes.
Angles of incidence and refraction are as follows:
A table of multiple magnification produced by eight stages and an eyepiece is given below: