Three piece prism eye-piece

• US 8,937,771 B2
• Filed: 12/12/2012
• Issued: 01/20/2015
• Est. Priority Date: 12/12/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Robbins, Steve J.
• Primary Examiner(s): Jones, James
• Application Number:
  US13/712,626
• Publication Number:
  US 20140160576A1
• Time in Patent Office: 769 Days
• Field of Search: 359/630
• US Class Current: 359/630
• 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 27/0172 characterised by optical features

Abstract

A prism eye piece and optical system including a prism eye piece and microdisplay are described herein. The prism eye piece may include three prisms. A main body prism has a surface that receives light from a source such as a microdisplay. Another prism has a surface that receives light from a source such as the real world. Both of these images are projected through a surface of still another prism that is proximate to an exit pupil. The surface of the prism proximate the exit pupil may be flat. Also the surface of the prism that receives light from a source such as the real world may be flat. These flat surfaces may be parallel to each other. This allows the light from the real world to be transmitted to the exit pupil without distortion.

Claims

1. An apparatus, comprising:

a three piece prism eyepiece comprising a first prism, a second prism, and a correcting plate;

the first prism having a first surface that is positioned to receive light from outside of the three piece prism eyepiece, the first prism having a second surface and a third surface, wherein at least one of the surfaces of the first prism is a free form surface;

the second prism having a first surface proximate to the second surface of the first prism and having a second surface, the second surface of the second prism being flat, there being an air gap between the first surface of the second prism and the second surface of the first prism; and

the correcting plate having a first surface proximate the third surface of the first prism, the correcting plate having a second surface that is flat, wherein the second surface of the second prism is in a first plane, wherein the second surface of the correcting plate is in a second plane that is parallel to the first plane, wherein the second surface of the correcting plate being configured to receive light from outside of the three piece prism eyepiece;

the first prism, the second prism, and the correcting plate are configured such that light that enters the first surface of the first prism from outside of the three piece prism eyepiece is emitted from the second surface of the second prism externally of the three piece prism eyepiece;

the first prism, the second prism, and the correcting plate are configured such that light that enters from outside of the three piece prism eyepiece into the second surface of the correcting plate is emitted from the second surface of the second prism externally from the three piece prism eyepiece.

2. The apparatus of claim 1, further comprising a microdisplay, the first surface of the first prism is configured to receive light from the microdisplay.

3. The apparatus of claim 2, wherein the first prism, the second prism, and the correcting plate are configured such that the light that enters the first surface of the first prism from the microdisplay is reflected at the second surface of the first prism by total internal reflection, then reflected at the third surface of the first prism, then transmitted out of the second surface of the first prism into the air gap, then into the first surface of the second prism, and then out of the second surface of the second prism.

4. The apparatus of claim 1, wherein a refracting index of the correcting plate is matched to a refracted index of the first prism.

5. The apparatus of claim 1, wherein the third surface of the first prism is rotationally symmetric.

18. The apparatus of claim 1, wherein the second surface of the first prism is a free form surface.

19. The apparatus of claim 1, wherein the second surface and the third surface of the first prism are each a free form surface.

20. The apparatus of claim 1, wherein the first surface, the second surface and the third surface of the first prism are each a free form surface.

6. A see through head mounted display apparatus, comprising:

a microdisplay;

a first prism having a first surface configured to receive light from the microdisplay, the first prism having a second surface and a third surface, wherein at least one of the second surface or the third surface of the first prism is a free form surface;

a second prism having a first surface configured to receive light from the second surface of the first prism, the second surface of the second prism configured to transmit light to an exit pupil, the second surface being flat, there being an air gap between the first surface of the second prism and the second surface of the first prism; and

a third prism having a first surface proximate to the third surface of the first prism, the third prism having a second surface that is flat, the flat second surface of the second prism is parallel to the flat second surface of the third prism, the first prism, the second prism, and the third prism are configured to transmit light that enters the second surface of the third prism from outside of the see through head mounted display apparatus to the exit pupil;

the first prism, the second prism, and the third prism are configured to transmit light from the microdisplay to the exit pupil.

7. The see through head mounted display apparatus of claim 6, wherein the microdisplay is one of a transmissive display, a reflective display, or an emissive display.

8. The see through head mounted display apparatus of claim 6, wherein the first prism, the second prism, and the third prism are a first set of prisms that provide light to a first eye of a user that wears the apparatus, and further comprising a second set of a first prism, a second prism, and a third prism that provide light to a second eye of the user.

9. The see through head mounted display apparatus of claim 6, wherein a prescription of the first surface of the second prism is matched to a prescription of the second surface of the first prism.

10. The see through head mounted display apparatus of claim 6, further comprising an aspherical lens between the microdisplay and the first surface of the first prism.

11. The see through head mounted display apparatus of claim 6, wherein the first surface of the third prism is in physical contact with the third surface of the first prism.

12. The see through head mounted display apparatus of claim 6, further comprising:

a processing device in communication with the microdisplay, the processing device provides an image to the microdisplay.

13. An optical system comprising:

a microdisplay;

a first prism having a first surface, a second surface, a third surface and a body, the first prism configured to receive light from the microdisplay into the first surface, wherein the second surface is a free form surface;

a second prism having a first surface, a second surface, and a body, the second surface of the second prism being proximate to the second surface of the first prism, the second surface of the second prism being flat, the first surface of the second prism being a free form surface; and

a correcting plate having a first surface, a second surface, and a body, the first surface of the correcting plate being proximate to the third surface of the first prism, the second surface of the correcting plate being flat and parallel to the flat second surface of the second prism;

light that enters the first surface of the first prism from the microdisplay is reflected at the second surface of the first prism by total internal reflection, then reflected at the third surface of the first prism, then transmitted out of the second surface of the first prism into an air gap between the first prism and second prism, then into the first surface of the second prism, and then out of the second surface of the second prism;

light that enters the second surface of the correcting plate is transmitted though the body of the correcting plate, through the body of the first prism, into the air gap, through the body of the second prism and out of the second surface of the second prism.

14. The optical system of claim 13, wherein the first prism has a first index of refraction, the correcting plate has a second index of refraction that is equal to the first index of refraction.

15. The optical system of claim 13, wherein the second surface of the first prism is a free form surface.

16. The optical system of claim 13, wherein the third surface of the first prism includes a partially reflective coating.

17. The optical system of claim 13, wherein the first surface of the correcting plate is conterminous with the third surface of the first prism.