Optical microscope which has optical modulation elements

• US 5,969,853 A
• Filed: 09/19/1997
• Issued: 10/19/1999
• Est. Priority Date: 09/19/1996
• Status: Expired due to Fees

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Takaoka, Hideyuki
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): CHERRY, EUNCHA P
• Application Number:
  US08/934,058
• Time in Patent Office: 760 Days
• Field of Search: 359/370, 359/371, 359/385, 359/386, 359/381
• US Class Current: 359/370
• CPC Class Codes: G02B 21/14 affording illumination for phase-contrast observation

Abstract

An optical microscope is provided with an aperture element 13 and an optical modulation element 14 that creates an image having the detecting sensitivity of the phase contrast imaging technique while simultaneously realizing an image having the three-dimensional sense provided by the modulation contrast imaging technique. There are four regions (two of which may have the same transmittance value and be contiguous in portions of the optical modulation element), are provided on a single optical modulation element 14, these regions including a first light absorbing region 14a having transmittance Ta, a second light absorbing region 14b having transmittance Tb and positioned adjacent to the first light absorbing region, a first light transmitting region 14c having a transmittance Tc and positioned adjacent to the first light absorbing region 14a, and a second light transmitting region 14d having a transmittance Td, wherein Ta is greater than Tb and less than Tc, Ta is less than Td, Tc is greater than 0.5, and Td is greater than 0.5.

Claims

1. An optical modulation element for use in an optical microscope having an optical axis, said optical modulation element including four regions comprising:

a first light absorbing region having a transmittance Ta;

a second light absorbing region having a transmittance Tb which is positioned adjacent to the first light absorbing region;

a first light transmitting region having a transmittance Tc which is positioned adjacent to the first light absorbing region; and

,

a second light transmitting region having a transmittance Td which is positioned adjacent the second light absorbing region at a side of the second light absorbing region that is opposite to said first light absorbing region, wherein the following conditional equations are satisfied

space="preserve" listing-type="equation">Tb<

Ta<

Tc

space="preserve" listing-type="equation">Ta<

Td

space="preserve" listing-type="equation">Tc>

0.5

space="preserve" listing-type="equation">Td>

0.5

wherein at least one of said four regions imparts a predetermined phase retardation to light transmitted therethrough.

2. The optical modulation element according to claim 1, wherein said first light absorbing region imparts a predetermined phase retardation to light transmitted by said first light absorbing region.

3. The optical modulation element according to claim 2 in combination with an optical microscope, said optical microscope including:

an illuminating optical system;

an aperture element positioned at a pupil plane of said illuminating optical system and having an aperture therein; and

an image-forming optical system having an objective lens;

wherein said optical modulation element is positioned at or near a pupil plane of the image-forming optical system that is conjugate to the pupil plane of said illuminating optical system.

4. The optical modulation element according to claim 1, wherein the second light absorbing region is substantially opaque, and Tc and Td each exceed 0.90.

5. The optical modulation element according to claim 4, wherein the first light absorbing region and the second light absorbing region are arranged along directions approximately orthogonal to the optical axis.

6. The optical modulation element according to claim 4 in combination with an optical microscope, said optical microscope including:

an illuminating optical system;

an aperture member positioned at a pupil plane of said illuminating optical system and having an aperture therein; and

an image-forming optical system having an objective lens;

wherein said optical modulation element is positioned at or near a pupil plane of the image-forming optical system that is conjugate to the pupil plane of said illuminating optical system.

7. The optical modulation element according to claim 1, wherein the first light absorbing region and the second light absorbing region are arranged along directions approximately orthogonal to the optical axis.

8. The optical modulation element according to claim 2, wherein the first light absorbing region and the second light absorbing region are arranged along directions approximately orthogonal to the optical axis.

9. The optical modulation element according to claim 8, wherein the second light absorbing region is substantially opaque, and Tc and Td each exceed 0.90.

10. The optical modulation element according to claim 9, and further comprising the first light absorbing region and the second light absorbing region each having sides that are equidistant, with the below conditional equation being satisfied

11. The optical modulation element according to claim 10, wherein the aperture of the aperture element is the shape of an angular segment of a ring centered on the optical axis, and the first light absorbing region and the second light absorbing region of the optical modulation element are each rings of a different size that are centered on the optical axis.

12. The apparatus as set forth in claim 11, said aperture element being rotatable about the optical axis.

13. The optical modulation element according to claim 11, wherein the second light absorbing region is arranged outward from the optical axis of said first light absorbing region, light passing through the innermost region of the aperture is incident on a sample being observed by said microscope, the optical microscope includes multiple objective lenses for observing an image having a selected magnification and the following conditional equation is satisfied

14. The apparatus according to claim 13, wherein:

when the objective lens having the smallest numerical aperture value is used, a part of said first light absorbing region is positioned at a circumference region of a pupil of said image-forming optical system.

15. The combination as recited in claim 14, said aperture element being rotatable about the optical axis.

16. The optical modulation element according to claim 7 in combination with an optical microscope, said optical microscope including:

an illuminating optical system;

an aperture element positioned at a pupil plane of said illuminating optical system and having an aperture therein; and

an image-forming optical system having an objective lens;

wherein said optical modulation element is positioned at or near a pupil plane of the image-forming optical system that is conjugate to the pupil plane of said illuminating optical system.

17. The optical modulation element according to claim 1 in combination with an optical microscope, said optical microscope including:

an illuminating optical system;

an aperture element positioned at a pupil plane of said illuminating optical system and having an aperture therein; and

an image-forming optical system having an objective lens;

wherein said optical modulation element is positioned at or near a pupil plane of the image-forming optical system that is conjugate to the pupil plane of said illuminating optical system.

18. The optical modulation element according to claim 1, wherein an aperture of an aperture element is the shape of an angular segment of a ring centered on the optical axis, and the first light absorbing region and the second light absorbing region of the optical modulation element are each rings of a different size that are centered on the optical axis.

19. The apparatus as set forth in claim 18, an aperture element being rotatable about the optical axis.

20. The optical modulation element as set forth in claim 1, wherein Tc equals Td, and the first light transmitting region and the second light transmitting region are contiguous in certain portions of said optical modulation element.