Zoom image-forming optical system and microscope equipped therewith

Patent metadata

Field	Value
Publication number	US-9383566-B2
Application number	US-201213480784-A
Country	US
Kind code	B2
Filing date	May 25, 2012
Priority date	May 31, 2011
Publication date	Jul 5, 2016
Grant date	Jul 5, 2016

Abstract

A zoom image-forming optical system used in combination with an infinity-correction objective lens, the zoom image-forming optical system including: a tube lens for condensing a luminous flux from the objective lens to form an intermediate image; and a relay lens with a zoom function for projecting the intermediate image onto an image plane. The relay lens includes a first lens group with positive power, a second lens group that belongs to a movable group with positive power, a third lens group that belongs to a movable group with positive or negative power, and a fourth lens group with negative power, in this order from the intermediate image side. The zoom image-forming optical system changes its magnifying power by moving the second lens group and the third lens group in an optical axis direction.

First claim

What is claimed is:

1. A zoom image-forming optical system used in combination with an infinity-correction objective lens, the zoom image-forming optical system comprising:
a tube lens for condensing a luminous flux from the objective lens to form an intermediate image; and
a relay lens with a zoom function for projecting the intermediate image onto an image plane,
wherein:
lenses of the relay lens consist of: (i) a first lens group with positive power; (ii) a second lens group that is a movable group with positive power; (iii) a third lens group that is a movable group with positive power; and (iv) a fourth lens group with negative power, in this order from a side of the intermediate image, and
the relay lens changes its magnifying power by moving the second lens group and the third lens group in an optical axis direction.

2. The zoom image-forming optical system according to claim 1 , wherein:
the relay lens includes an aperture stop between the second lens group and the third lens group, the aperture stop moving in a direction of an optical axis, and
the aperture stop is arranged at an optically conjugated position with reference to an exit pupil position of the objective lens, or in close proximity to the optically conjugated position.

3. The zoom image-forming optical system according to claim 2 , wherein:
a conditional expression
−2.7 <F TL /F MIN <−0.9

is satisfied, where F TL indicates a focal length of the tube lens, and F MIN indicates a compound focal length between the tube lens and the relay lens in a low-power end state.

4. The zoom image-forming optical system according to claim 2 , wherein:
a conditional expression
−0.16 <F TL /F MAX <−0.07

is satisfied, where F TL indicates a focal length of the tube lens, and F MAX indicates a compound focal length between the tube lens and the relay lens in a high-power end state.

5. The zoom image-forming optical system according to claim 2 , wherein:
a conditional expression
0.05<φ E/L PI <0.17

is satisfied, where φE indicates a pupil diameter of the objective lens in a high-power end state, and L PI indicates a distance from the exit pupil position of the objective lens to a primary image-forming position at which the intermediate image is formed by the tube lens.

6. The zoom image-forming optical system according to claim 2 , wherein:
conditional expressions
−17< L PC /F MIN <−5

−1.3< L PC /F MAX <−0.3

are satisfied, where F MIN indicates a compound focal length between the tube lens and the relay lens in a low-power end state, F MAX indicates a compound focal length between the tube lens and the relay lens in a high-power end state, and L PC indicates a distance from the exit pupil position of the objective lens to a secondary image-forming position at which an image is formed by the relay lens.

7. The zoom image-forming optical system according to claim 2 , wherein:
the tube lens includes a convex lens, and
a conditional expression
120< vd TLP * nd TLP <140

is satisfied, where vd TLP indicates an Abbe number of the convex lens, and nd TLP indicates an index of refraction for a d Line of the convex lens.

8. The zoom image-forming optical system according to claim 2 , wherein the aperture stop is a variable stop in which a stop diameter is variable.

9. A microscope including the zoom image-forming optical system according to claim 2 .

10. A zoom image-forming optical system used in combination with an infinity-correction objective lens, the zoom image-forming optical system comprising:
a tube lens for condensing a luminous flux from the objective lens to form an intermediate image; and
a relay lens with a zoom function for projecting the intermediate image onto an image plane,
wherein:
the relay lens includes: (i) a first lens group with positive power; (ii) a second lens group that belongs to a movable group with positive power; (iii) a third lens group that belongs to a movable group with positive or negative power; and (iv) a fourth lens group with negative power, in this order from a side of the intermediate image,
the relay lens changes its magnifying power by moving the second lens group and the third lens group in an optical axis direction,
the relay lens includes an aperture stop between the second lens group and the third lens group, the aperture stop moving in a direction of an optical axis,
the aperture stop is arranged at an optically conjugated position with reference to an exit pupil position of the objective lens, or in close proximity to the optically conjugated position, and
a conditional expression
−2.7 <F TL /F MIN <−0.9

is satisfied, where F TL indicates a focal length of the tube lens, and F MIN indicates a compound focal length between the tube lens and the relay lens in a low-power end state.

11. A zoom image-forming optical system used in combination with an infinity-correction objective lens, the zoom image-forming optical system comprising:
a tube lens for condensing a luminous flux from the objective lens to form an intermediate image; and
a relay lens with a zoom function for projecting the intermediate image onto an image plane,
wherein:
the relay lens includes: (i) a first lens group with positive power; (ii) a second lens group that belongs to a movable group with positive power; (iii) a third lens group that belongs to a movable group with positive or negative power; and (iv) a fourth lens group with negative power, in this order from a side of the intermediate image,
the relay lens changes its magnifying power by moving the second lens group and the third lens group in an optical axis direction,
the relay lens includes an aperture stop between the second lens group and the third lens group, the aperture stop moving in a direction of an optical axis,
the aperture stop is arranged at an optically conjugated position with reference to an exit pupil position of the objective lens, or in close proximity to the optically conjugated position, and
a conditional expression
−0.16 <F TL /F MAX <−0.07

is satisfied, where F TL indicates a focal length of the tube lens, and F MAX indicates a compound focal length between the tube lens and the relay lens in a high-power end state.

12. A zoom image-forming optical system used in combination with an infinity-correction objective lens, the zoom image-forming optical system comprising:
a tube lens for condensing a luminous flux from the objective lens to form an intermediate image; and
a relay lens with a zoom function for projecting the intermediate image onto an image plane,
wherein:
the relay lens includes: (i) a first lens group with positive power; (ii) a second lens group that belongs to a movable group with positive power; (iii) a third lens group that belongs to a movable group with positive or negative power; and (iv) a fourth lens group with negative power, in this order from a side of the intermediate image,
the relay lens changes its magnifying power by moving the second lens group and the third lens group in an optical axis direction,
the relay lens includes an aperture stop between the second lens group and the third lens group, the aperture stop moving in a direction of an optical axis,
the aperture stop is arranged at an optically conjugated position with reference to an exit pupil position of the objective lens, or in close proximity to the optically conjugated position, and
a conditional expression
0.05<φ E/L PI <0.17

is satisfied, where φE indicates a pupil diameter of the objective lens in a high-power end state, and L PI indicates a distance from the exit pupil posi

Assignees

• Yamamoto Hirofumi
• Olympus Corp

Inventors

• Yamamoto Hirofumi

Classifications

• G02B21/082

  for incident illumination only · CPC title

• G02B21/025 Primary

  with variable magnification (variable magnification G02B15/00) · CPC title