Microscope photography lens system
AssigneeNikon Corporation
InventorYumiko Ouchi
Life of this patent
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Abstract
The present invention allows one to take an intermediate image formed by a microscope objective lens system and reform a clear image of it, at relatively low magnification, on a film surface. The present invention provides for a lens system which comprises, in order, from the observed object end, a first lens group having a convex surface facing toward the objective lens system end, and having positive refractive power, a second lens group, positioned to the rear of the intermediate image, and having negative refractive power, and a third lens group having positive refractive power. The lenses in the system are set to follow predetermined parameters.
Claims10
A microscope photography lens system for directing an intermediate image of an observed object formed by an objective lens system onto a photographic surface, wherein said microscope photography lens system comprises, in order, from the observed object:
- a) a first lens group having a convex surface facing toward the objective lens system and having an overall positive refractive power;
- b) a second lens group having a concave surface facing toward the objective lens system, which is located between said intermediate image and a third lens group, and having an overall negative refractive power;
- and
- c) said third lens group having at least two lens elements with a front end facing towards the objective lens system and a rear end, wherein the third lens group has a positive refractive power and wherein the following mathematical relationships are satisfied:
- 1) -0.1.gtoreq.d/L.gtoreq.-0.4;
- 2) 0.1.ltoreq.D.sub.2 /D.sub.1 .ltoreq.1.0;
- 3) 0.2.ltoreq..vertline.r.sub.21 /f.sub.3 .vertline..ltoreq.0.6;
- and
- 4) 15.ltoreq.(V.sub.3(max) -V.sub.3(min));
- wherein:
- d is a distance from the intermediate image to the convex surface of said first lens group;
- L is a distance from the convex surface of said first lens group to the rear end of said third lens group;
- D.sub.1 is a distance between said first lens group and said second lens group;
- D.sub.2 is a distance between said second lens group and said third lens group;
- r.sub.21 is a curvature radius of the concave surface of said second lens group facing towards the objective lens system;
- f.sub.3 is a focal length of said third lens group;
- .upsilon..sub.3(max) is the highest Abbe number from the lens elements of said third lens group;
- .upsilon..sub.3(min) is the lowest Abbe number from the lens elements of the third lens group;
- and
- all distances are positive when they are measured to the photographic surface side from the observed object side.
A microscope photography lens system for directing an intermediate image of an observed object formed by an objective lens system onto a photographic surface, wherein said microscope photography lens system comprises, in order, from the observed object:
- a) a first lens group having a convex surface facing toward the objective lens system and having an overall positive refractive power;
- b) a second lens group having a concave surface facing toward the objective lens system, which is located between said intermediate image, and a third lens group, and having an overall negative refractive power;
- and
- c) a third lens group having an overall positive refractive power and wherein the following mathematical relationships are satisfied:
- 1) -0.1.gtoreq.d/L.gtoreq.-0.4;
- 2) 0.1.ltoreq.D.sub.2 /D.sub.1 .ltoreq.1.0;
- 3) 0.2.ltoreq..vertline.r.sub.21 /f.sub.3 .vertline..ltoreq.0.6;
- and
- wherein:
- d is a distance from the intermediate image to the convex surface of said first lens group;
- L is a distance from the convex surface of said first lens group to the rear end of said third lens group;
- D.sub.1 is a distance between said first lens group and said second lens group;
- D.sub.2 is a distance between said second lens group and said third lens group;
- r.sub.21 is a curvature radius of the concave surface of said second lens group facing towards the objective lens system;
- f.sub.3 is a focal length of said third lens group;
- and
- all distances are positive when they are measured to the photographic surface side from the observed object side.
Dependencies are inferred from the claim text.