Infrared optical element for proximity sensor system

• US 10,551,500 B2
• Filed: 05/14/2019
• Issued: 02/04/2020
• Est. Priority Date: 04/10/2018
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Facebook Technologies, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Appleby, Matthew Christopher, Yang, Dong, Liu, Fei
• Primary Examiner(s): Gaworecki, Mark R
• Application Number:
  US16/412,268
• Publication Number:
  US 20190310369A1
• Time in Patent Office: 266 Days
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G02B 27/0093 with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking
• CPC Class Codes: G02B 27/017 Head mounted

Abstract

An optical device includes an optical element. The optical element includes a first surface configured to receive light in a first direction and a second surface that is non-parallel to the first surface. The second surface is configured to transmit a first portion of the light in a second direction that is different from the first direction and internally reflect a second portion of the light that is distinct from the first portion of the light. The optical element further includes a third surface configured to receive the second portion of the light from the second surface and reduce internal reflection of the second portion of the light by the third surface. Also disclosed is a method of steering light by the optical device.

Claims

1. An optical device comprising:

an optical element, the optical element including;

a first surface configured to receive light in a first direction;

a second surface that is non-parallel to the first surface, the second surface configured to transmit a first portion of the light in a second direction that is different from the first direction and internally reflect a second portion of the light that is distinct from the first portion of the light; and

a third surface configured to receive the second portion of the light from the second surface and reduce internal reflection of the second portion of the light by the third surface.

2. The optical device of claim 1, further including a light emitter configured to project the light in the first direction toward the first surface of the optical element.

3. The optical device of claim 2, wherein the first surface is configured so that the light emitted from the light emitter impinges on the first surface at an angle that is less than a critical angle for the light emitted from the light emitter.

4. The optical device of claim 2, further including an absorbing material configured to absorb a portion of the light from the light emitter exiting from the optical element through the third surface.

5. The optical device of claim 4, wherein the absorbing material is positioned on the third surface.

6. The optical device of claim 4, wherein the absorbing material is positioned away from the third surface.

7. The optical device of claim 1, wherein the first surface includes a structured surface.

8. The optical device of claim 7, wherein the first surface includes a prism structure, the prism structure configured to receive the light in the first direction and steer the light to a third direction distinct from the first direction and the second direction.

9. The optical device of claim 7, wherein the first surface includes a plurality of Fresnel structures.

10. The optical device of claim 1, wherein the second surface includes an anti-reflection coating.

11. The optical device of claim 1, wherein the second direction is different from a surface normal of the second surface.

12. The optical device of claim 1, wherein the third surface is a flat surface.

13. The optical device of claim 1, wherein the third surface is adjacent to the first surface, and the third surface is non-parallel to the first surface and to the second surface.

14. The optical device of claim 13, wherein the third surface is configured so that the second portion of the light impinges on the third surface at an angle that is less than a critical angle for the second portion of the light.

15. The optical device of claim 1, wherein the second surface is configured so that the light from the first surface impinges on the second surface at an angle that is distinct from a surface normal of the second surface.

16. The optical device of claim 1, wherein the optical element is made of infrared transmitting plastic and the light is infrared light.

17. The optical device of claim 1, further including a sensor configured to detect at least a portion of the first portion of the light returned from an object outside the optical device and transmitted through the second surface and the first surface of the optical element.

18. A method of steering light, the method comprising:

at an optical device including an optical element having a first surface, a second surface, and a third surface;

receiving, on the first surface, light in a first direction;

transmitting, through the second surface that is non-parallel to the first surface, a first portion of the light in a second direction that is different from the first direction;

internally reflecting, at the second surface, a second portion of the light that is distinct from the first portion of the light;

receiving, with the third surface, the second portion of the light from the second surface; and

reducing internal reflection of the second portion of the light on the third surface.

19. The method of claim 18, further including:

projecting, with a light emitter, the light in the first direction toward the first surface of the optical element.

20. The method of claim 18, wherein the first surface includes a prism structure, and the method further includes receiving, with the prism structure, the light in the first direction and steering the light to a third direction distinct from the first direction and the second direction.