Optical path splitting element and image display apparatus using the same

• US 6,757,107 B2
• Filed: 04/25/2002
• Issued: 06/29/2004
• Est. Priority Date: 04/25/2001
• Status: Expired due to Term

• Current Assignee: Olympus Corporation
• Original Assignee: Olympus Corporation
• Inventors: Togino, Takayoshi
• Primary Examiner(s): Dang, Hung Xuan
• Application Number:
  US10/131,031
• Publication Number:
  US 20030072092A1
• Time in Patent Office: 796 Days
• Field of Search: 359/631, 359/632, 359/633, 359/629, 359/627, 359/625, 359/619
• US Class Current: 359/631
• CPC Class Codes: G02B 2027/0156 with optionally usable elements
• CPC Class Codes: G02B 27/0172 characterised by optical features

Abstract

An optical path splitting element for splitting a light beam from a single object into at least two optical paths is made compact in size by using a three-dimensional optical system and given a power to reduce the number of components thereof. An image display apparatus uses the optical path splitting element. The optical path splitting element has a prism member having an entrance surface through which the light beam from the object enters the prism member, at least one reflecting surface reflecting the light beam within the prism member, and an exit surface through which the light beam exits the prism member. The prism member has at least one rotationally asymmetric surface. At least one optical functional surface is a discontinuous surface formed from at least two surfaces adjacent to each other. The other optical functional surfaces are common to the at least two optical paths.

Claims

1. An optical path splitting element for splitting a light beam from a single object into at least two optical paths, said optical path splitting element comprising a prism member formed from a medium having a refractive index (n) larger than 1 (n>

1), said prism member having;

an entrance surface through which the light beam from said object enters said prism member;

at least one reflecting surface reflecting the light beam within said prism member; and

an exit surface through which the light beam exits said prism member;

said prism member having at least one rotationally asymmetric surface;

wherein at least one optical functional surface of said prism member is a discontinuous surface formed from at least two surfaces adjacent to each other, and other optical functional surfaces of said prism member are common to said at least two optical paths.

2. An image display apparatus comprising:

an optical path splitting element for splitting a light beam from a single object into at least two optical paths;

an image display device disposed at a position of said object; and

an ocular optical system having at least a positive power to project the at least two optical paths split by said optical path splitting element near an eyeball of an observer;

wherein said optical path splitting element has a prism member formed from a medium having a refractive index (n) larger than 1 (n>

1), said prism member having;

an entrance surface through which the light beam from said object enters said prism member;

at least one reflecting surface reflecting the light beam within said prism member; and

an exit surface through which the light beam exits said prism member;

said prism member having at least one rotationally asymmetric surface;

wherein at least one optical functional surface of said prism member is a discontinuous surface formed from at least two surfaces adjacent to each other, and other optical functional surfaces of said prism member are common to said at least two optical paths.

3. An image display apparatus according to claim 2, wherein said ocular optical system has at least one rotationally asymmetric surface.

4. An image display apparatus according to claim 2, wherein said ocular optical system is a reflecting optical system.

5. An image display apparatus according to claim 2, wherein said ocular optical system is a refracting optical system.

6. An image display apparatus according to claim 2, wherein said ocular optical system is a diffractive optical system.

7. An image display apparatus according to claim 2, wherein said ocular optical system has directional diffusion properties.

8. An image display apparatus according to claim 2, wherein a virtual image of each optical path is formed near a point of intersection between optical axes of said at least two optical paths after exiting said ocular optical system.

9. An image display apparatus according to claim 2, wherein exit pupils formed in said at least two optical paths exiting said ocular optical system are disposed apart from each other by a distance corresponding to an interpupillary distance of the observer.

10. An image display apparatus according to claim 2, wherein the at least two optical paths split by said optical path splitting element intersect each other near said ocular optical system, and a virtual image of each optical path is formed near said ocular optical system.

11. An image display apparatus according to claim 2, wherein said discontinuous surface of said optical path splitting element that is formed from at least two surfaces is a surface near a pupil position within said optical path splitting element.

12. An image display apparatus according to claim 2, wherein said ocular optical system is retractable from the optical paths so that said image display apparatus is usable as a projector.

13. An image display apparatus according to claim 2, wherein a position of said image display device is adjustable relative to said optical path splitting element.

14. An image display apparatus according to claim 2, further comprising:

a light source for illuminating said image display device; and

an external light source unit removably attached to a body of said image display apparatus.