Optical system and image display apparatus

• US 5,768,025 A
• Filed: 08/20/1996
• Issued: 06/16/1998
• Est. Priority Date: 08/21/1995
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Togino, Takayoshi, Nakaoka, Masaya
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US08/697,068
• Time in Patent Office: 665 Days
• Field of Search: 359/630, 359/631, 359/633, 359/637, 359/640, 345/7, 345/8, 345/9
• US Class Current: 359/633
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00
• CPC Class Codes: G02B 17/0816 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0832 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0848 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0856 comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
• CPC Class Codes: G02B 17/086 wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 25/001 Eyepieces
• CPC Class Codes: G02B 27/0172 characterised by optical features

Abstract

An optical system which is compact, lightweight and satisfactorily corrected for aberrations and may be suitably used as an imaging optical system or an ocular optical system for a head- or face-mounted image display apparatus which forms no intermediate image. The optical system includes an optical member (7) and a diffraction optical element (8), which are decentered with respect to each other. The optical member (7) has at least three adjacent optical surfaces, at least one of which is a curved surface. At least two reflections take place between the optical surfaces. The space between the optical surfaces is filled with a medium having a refractive index larger than 1. Light rays emitted from an image display device (6) enter the optical member (7) through a first transmitting surface (5) disposed to face the image display device (6) and are reflected by a first reflecting surface (3). The reflected light rays are reflected by a second reflecting surface (4) and led to an observer'"'"'s eyeball through a second transmitting surface (3).

Claims

1. An image display apparatus comprising:

an image display device that displays an image;

an ocular optical system that leads the image displayed by said image display device to an observer'"'"'s eyeball without forming an intermediate real image; and

a retaining component that retains both said image display device and said ocular optical system on an observer'"'"'s head or face,

wherein said image display apparatus includes a light-blocking member provided between said ocular optical system and said observer'"'"'s eyeball, and

said ocular optical system has three to four optical surfaces, and an area surrounded by said optical surfaces is filled with a transparent medium having a refractive index larger than 1, said optical surfaces including a first surface disposed to face said image display device, a second surface disposed on an observer'"'"'s visual axis to face an observer'"'"'s pupil, and a third surface disposed on said observer'"'"'s visual axis between said second surface and said observer'"'"'s pupil.

2. An image display apparatus according to claim 1, wherein said second surface is a reflecting surface.

3. An image display apparatus according to claim 1, wherein light rays emitted from said image display device enter said ocular optical system through said first surface and are led to said observer'"'"'s eyeball through said third surface.

4. An image display apparatus according to claim 3, wherein said third surface is identical with said first surface.

5. An image display apparatus according to claim 1, wherein light rays emitted from said image display device enter said ocular optical system through said first surface and are reflected by a fourth surface and said second surface in the mentioned order before being led to said observer'"'"'s eyeball through said third surface.

6. An image display apparatus according to claim 5, wherein said fourth surface is identical with said third surface.

7. An image display apparatus according to claim 6, wherein the reflection at said fourth surface is total reflection.

8. An image display apparatus according to claim 5, wherein said fourth surface is identical with said first surface.

9. An image display apparatus according to claim 5, wherein said second surface is identical with said first surface.

10. An image display apparatus according to claim 1, wherein said light-blocking member is provided with an aperture.

11. An image display apparatus according to claim 10, which satisfies the following condition:

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

+.o slashed./2≦

R≦

2 (Ltanθ

+.o slashed./2)(22)

where R is a distance from an edge of the aperture in said light-blocking member to said observer'"'"'s visual axis in a section containing a center of said image display device and said observer'"'"'s visual axis, .o slashed. is a diameter of an exit pupil of said ocular optical system, L is an eye relief of said ocular optical system, and θ

is a half view angle in the section containing the center of said image display device and said observer'"'"'s visual axis.

12. An image display apparatus according to claim 10, which satisfies the following condition:

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

+.o slashed./2≦

R≦

1.2 (Ltanθ

+.o slashed./2)(22'"'"')

where R is a distance from an edge of the aperture in said light-blocking member to said observer'"'"'s visual axis in a section containing a center of said image display device and said observer'"'"'s visual axis, .o slashed. is a diameter of an exit pupil of said ocular optical system, L is an eye relief of said ocular optical system, and θ

is a half view angle in the section containing the center of said image display device and said observer'"'"'s visual axis.

13. An image display apparatus according to claim 1, wherein said light-blocking member is in close contact with said ocular optical system.

14. An image display apparatus comprising:

an image display device that displays an image;

an ocular optical system that leads the image displayed by said image display device to an observer'"'"'s eyeball without forming an intermediate real image; and

a retaining component that retains both said image display device and said ocular optical system on an observer'"'"'s head or face,

wherein said image display apparatus includes a numerical aperture limiting member disposed between said image display device and said ocular optical system to limit a numerical aperture of a bundle of light rays emitted from said image display device, and

said ocular optical system has three to four optical surfaces, and an area surrounded by said optical surfaces is filled with a transparent medium having a refractive index larger than 1, said optical surfaces including a first surface disposed to face said image display device, a second surface disposed on an observer'"'"'s visual axis to face an observer'"'"'s pupil, and a third surface disposed on said observer'"'"'s visual axis between said second surface and said observer'"'"'s pupil.

15. An image display apparatus according to claim 14, wherein said second surface is a reflecting surface.

16. An image display apparatus according to claim 14, wherein light rays emitted from said image display device enter said ocular optical system through said first surface and are led to said observer'"'"'s eyeball through said third surface.

17. An image display apparatus according to claim 16, wherein said third surface is identical with said first surface.

18. An image display apparatus according to claim 14, wherein light rays emitted from said image display device enter said ocular optical system through said first surface and are reflected by a fourth surface and said second surface in the mentioned order before being led to said observer'"'"'s eyeball through said third surface.

19. An image display apparatus according to claim 18, wherein said fourth surface is identical with said third surface.

20. An image display apparatus according to claim 19, wherein the reflection at said fourth surface is total reflection.

21. An image display apparatus according to claim 18, wherein said fourth surface is identical with said first surface.

22. An image display apparatus according to claim 18, wherein said second surface is identical with said first surface.

23. An image display apparatus according to claim 14, wherein said numerical aperture limiting member limits the numerical aperture of the bundle of light rays emitted from said image display device such that an angle θ

between a normal to said image display device and a marginal light ray on an observer'"'"'s pupil side is not greater than 45°

.

24. An image display apparatus according to claim 14, wherein said numerical aperture limiting member limits the numerical aperture of the bundle of light rays emitted from said image display device such that an angle θ

between a normal to said image display device and a marginal light ray on an observer'"'"'s pupil side is not greater than 20°

.

25. An image display apparatus according to claim 14, wherein said numerical aperture limiting member is a louver.

26. An image display apparatus according to claim 14, wherein said numerical aperture limiting member is an optical fiber plate.

27. An image display apparatus according to claim 14, wherein said numerical aperture limiting member is a field selecting glass.

28. An image display apparatus comprising:

an image display device that displays an image;

an ocular optical system that leads the image displayed by said image display device to an observer'"'"'s eyeball without forming an intermediate real image; and

a retaining component that retains both said image display device and said ocular optical system on an observer'"'"'s head or face,

said image display device being a transmission type liquid crystal display device, said transmission type liquid crystal display device using light limited in numerical aperture as illuminating light therefor,

wherein said ocular optical system has three to four optical surfaces, and an area surrounded by said optical surfaces is filled with a transparent medium having a refractive index larger than 1, said optical surfaces including a first surface disposed to face said image display device, a second surface disposed on an observer'"'"'s visual axis to face an observer'"'"'s pupil, and a third surface disposed on said observer'"'"'s visual axis between said second surface and said observer'"'"'s pupil.

29. An image display apparatus according to claim 28, wherein said second surface is a reflecting surface.

30. An image display apparatus according to claim 29, wherein light rays emitted from said image display device enter said ocular optical system through said first surface and are led to said observer'"'"'s eyeball through said third surface.

31. An image display apparatus according to claim 30, wherein said third surface is identical with said first surface.

32. An image display apparatus according to claim 29, wherein light rays emitted from said image display device enter said ocular optical system through said first surface and are reflected by a fourth surface and said second surface in the mentioned order before being led to said observer'"'"'s eyeball through said third surface.

33. An image display apparatus according to claim 32, wherein said fourth surface is identical with said third surface.

34. An image display apparatus according to claim 33, wherein the reflection at said fourth surface is total reflection.

35. An image display apparatus according to claim 32, wherein said fourth surface is identical with said first surface.

36. An image display apparatus according to claim 32, wherein said second surface is identical with said first surface.