CASCADING OPTICS IN OPTICAL COMBINERS OF HEAD MOUNTED DISPLAYS

• US 20140232651A1
• Filed: 02/15/2013
• Published: 08/21/2014
• Est. Priority Date: 02/15/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Starner, Thad E., Kress, Bernard
• Granted Patent: US 9,223,139 B2
• Time in Patent Office: Days
• US Class Current: 345/158
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 2027/0187 slaved to motion of at least a part of the body of the user, e.g. head, eye
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence

Abstract

An apparatus for a head mounted display includes a display module for launching display light along a forward propagating path. The apparatus also includes a light relay to receive the display light. The light relay includes a first optic disposed along the forward propagating path. The light relay also includes a second optic disposed along the forward propagating path between the first optic and the display module. The first optic is configured to direct the display light in an eye-ward direction and the second optic is configured to direct the display light in an eye-ward direction.

Claims

1. An apparatus for a head mounted display (“

HMD”

), the apparatus comprising;

a display module for launching display light along a forward propagating path;

a light relay optically coupled to receive the display light, wherein the light relay includes;

a first switchable holographic optic (“

SHO”

) disposed along the forward propagating path; and

a second SHO disposed along the forward propagating path between the first SHO and the display module; and

a controller coupled to selectively activate the first and second SHOs, wherein the first SHO is configured to direct at least a first portion of the display light toward an eye-ward side of the light relay when the first SHO is activated by the controller, and wherein the second SHO is configured to direct at least a second a portion of the display light toward the eye-ward side of the light relay when the second SHO is activated by the controller.

2. The apparatus of claim 1, wherein the controller is also coupled to the display module to coordinate the launching of the display light with selectively activating the first and second SHOs.

3. The apparatus of claim 1 further comprising an eye-tracking module positioned to monitor an eye to be brought in proximity to the eye-ward side of the light relay, wherein the controller is coupled receive gaze data generated by the eye-tracking module and coupled to selectively activate the first and second SHGs in responsive to the gaze data generated by the eye-tracking module.

4. The apparatus of claim 1, wherein the first SHO is configured to substantially collimate the first portion of the display light when the first SHO is activated by the controller and configured to appear essentially transparent to the display light propagating along the forward propagating path when the first SHO is not activated by the controller,

and wherein the second SHO is configured to substantially collimate the second portion of the display light propagating along the forward propagating path when the second SHO is activated by the controller and configured to appear essentially transparent to the display light propagating along the forward propagating path when the second SHO is not activated by the controller.

5. The apparatus of claim 1, wherein the light relay further includes a third SHO disposed along the forward propagating path between the first SHO and the second SHO, wherein the controller is coupled to selectively activate the third SHO, and wherein the third SHO is configured to direct at least a third portion of the display light toward the eye-ward side of the light relay when the third SHO is activated by the controller.

6. The apparatus of claim 5, wherein the first SHO includes a first holographic medium written with a first, second, and third Bragg selectivity to cause a first, second, and third spectrum of the display light to be collimated and reflected toward the eye-ward side of the light relay when the first SHO is activated by the controller,

and wherein the second SHO includes a second holographic medium written with the first, second, and third Bragg selectivity to cause the first, second, and third spectrum of the display light to be collimated and reflected toward the eye-ward side of the light relay when the second SHO is activated by the controller

and wherein the third SHO includes a third holographic medium written with the first, second, and third Bragg selectivity to cause the first, second, and third spectrum of the display light to be collimated and reflected toward the eye-ward side of the light relay when the third SHO is activated by the controller.

7. The apparatus of claim 6, wherein a light source of the display module includes:

a first light source that emits the first spectrum of the display light;

a second light source that emits the second spectrum of the display light; and

a third light source that emits the third spectrum of the display light.

8. The apparatus of claim 1, wherein the first SHO includes first holographic polymer-dispersed liquid crystals (“

H-PDLC”

) and the second SHO includes second H-PDLC.

9. The apparatus of claim 1, wherein the display module include a liquid crystal on silicon (“

LCOS”

) display.

10. The apparatus of claim 1 further comprising a frame assembly for wearing on a head of a user, wherein the display module is mounted to the frame assembly.

11. An apparatus for a head mounted display (“

HMD”

), the apparatus comprising;

a display module for launching display light along a forward propagating path; and

a light relay optically coupled to receive the display light, wherein the light relay includes;

a first holographic optic disposed along the forward propagating path and configured to direct and focus a first spectrum of the display light toward an eye-ward side of the light relay; and

a second holographic optic disposed along the forward propagating path between the second holographic optic and the display module, wherein the second holographic optic is configured to direct and focus a second spectrum of the display light toward the eye-ward side of the light relay and configured to pass the second spectrum of the display light to the first holographic optic.

12. The apparatus of claim 11, wherein the first spectrum of the display light includes a first image and the first holographic optic is further configured to direct the first image to a first image region, and wherein the second spectrum of the display light includes a second image and the second holographic optic is further configured to direct the second image to a second image region that is different than the first image region.

13. The apparatus of claim 11 wherein the light relay further includes a third holographic optic disposed along the forward propagating path between the first holographic optic and the second holographic optic, wherein the third holographic optic is configured to direct a third spectrum of the display light toward the eye-ward side of the light relay.

14. The apparatus of claim 13, wherein the first, second, and third spectrums are different colors of visible light, and wherein the first spectrum of the display light includes a first image and the first holographic optic is further configured to direct the first image to a first image region, the second spectrum of the display light includes a second image and the second holographic optic is further configured to direct the second image to a second image region that is different than the first image region, and the third spectrum of the display light includes a third image and the third holographic optic is further configured to direct the third image to a third image region that is different than the first and second image regions.

15. The apparatus of claim 13, wherein the first holographic optic includes a first Bragg grating that is angle-tuned to reflect the first spectrum of the display light, the second holographic optic includes a second Bragg grating that is angle-tuned to reflect the second spectrum of the display light, and the third holographic optic includes a third Bragg grating that is angle-tuned to reflect the third spectrum of the display light.

16. The apparatus of claim 11 further comprising a frame assembly for wearing on a head of a user, wherein the display module is mounted to the frame assembly.

17. An apparatus for a head mounted display (“

HMD”

), the apparatus comprising;

a display module for launching display light along a forward propagating path;

an end reflector positioned to reflect back the display light along a reverse propagating path;

a light relay disposed between the display module and the end reflector, wherein the light relay includes;

a first switchable optic disposed along the forward propagating path; and

a second switchable optic disposed along the forward propagating path between the first switchable optic and the display module; and

a controller coupled to selectively activate the first and second switchable optics, wherein the first switchable optic is configured to direct the display light propagating along the reverse propagating path toward an eye-ward side of the light relay when the first switchable optic is activated by the controller, and wherein the second switchable optic is configured to direct the display light propagating along the reverse propagating path toward the eye-ward side of the light relay when the second switchable optic is activated by the controller.

18. The apparatus of claim 17, wherein the controller is also coupled to the display module to coordinate the launching of the display light with selectively activating the first and second switchable optics.

19. The apparatus of claim 17, wherein the end reflector is optically configured to receive the display light propagating along the forward propagating path and reflect the display light as substantially collimated display light propagating along the reverse propagating path.

20. The apparatus of claim 19, wherein the first switchable optic includes a first switchable mirror and the second switchable optic includes a second switchable mirror.

21. The apparatus of claim 19, wherein the first switchable optic includes a first switchable holographic optic and the second switchable optic includes a second switchable holographic optic.

22. The apparatus of claim 21, wherein the first switchable holographic optic includes first holographic polymer-dispersed liquid crystals (“

H-PDLC”

) and the second switchable holographic optic includes second H-PDLC.

23. The apparatus of claim 17, wherein the end reflector includes a planar mirror, and wherein the first switchable optic includes a first switchable holographic optic and a first beam splitter and the second switchable optic includes a second switchable holographic optic and a second beam splitter, the first and second beam splitters facing the planar mirror,

wherein the first switchable holographic optic is configured to substantially collimate the display light propagating along the forward propagating path when the first switchable optic is activated by the controller and to appear essentially transparent to the display light propagating along the forward propagating path when the first switchable optic is not activated by the controller,

and wherein the second switchable holographic optic is configured to substantially collimate the display light propagating along the forward propagating path when the second switchable optic is activated by the controller and to appear essentially transparent to the display light propagating along the forward propagating path when the second switchable optic is not activated by the controller.

24. The apparatus of claim 17 further comprising a frame assembly for wearing on a head of a user, wherein the display module is mounted to the frame assembly.