Beam multiplier that can be used as an exit-pupil expander and related system and method

• US 20050237615A1
• Filed: 07/12/2004
• Published: 10/27/2005
• Est. Priority Date: 04/23/2004
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Tegreene, Clarence T., Urey, Hakan
• Granted Patent: US 7,339,737 B2
• Time in Patent Office: Days
• US Class Current: 359/566
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 3/0062 Stacked lens arrays, i.e. refractive surfaces arranged in at least two planes, without structurally separate optical elements in-between
• CPC Class Codes: G02B 5/1871 Transmissive phase gratings

Abstract

A beam multiplier includes a beam-multiplying layer and an adjacent optical layer. The beam-multiplying layer is operable to generate output beamlets of light from an input beam of light, and the optical layer has an adjustable index of refraction. By switching the index of refraction of the optical layer between first and second values, one can switch the beam multiplier to a first state (e.g., “on”) where it generates the output beamlets of light, and can switch the beam multiplier to a second state (e.g., “off”) where it passes the input beam of light but does not generate the output beamlets. And by using the beam multiplier as an exit-pupil expander, one can switch the exit-pupil expander to a first state where it generates multiple exit-pupil images, and to a second state where it generates only a single exit-pupil image.

Claims

1. A beam multiplier, comprising:

a beam-multiplying layer operable to generate output beamlets of light from an input beam of light; and

an optical layer adjacent to the beam-multiplying layer and having an adjustable index of refraction.

2. The beam multiplier of claim 1 wherein the beam multiplier layer is transparent.

3. The beam multiplier of claim 1, further comprising a reflector operable to reflect in a first direction light passing through the beam-multiplying layer in second direction.

4. The beam multiplier of claim 3 wherein the reflector is integral with the beam-multiplying layer.

5. The beam multiplier of claim 3 wherein the reflector is separate from the beam-multiplying layer.

6. The beam multiplier of claim 1 wherein the optical layer is transparent.

7. The beam multiplier of claim 1 wherein the optical layer comprises an electro-optic layer.

8. The beam multiplier of claim 1 wherein the optical layer comprises a thermo-optic layer.

9. The beam multiplier of claim 1 wherein the beam-multiplying layer comprises a diffractive optical element.

10. The beam multiplier of claim 1 wherein the beam-multiplying layer comprises a refractive optical element.

11. The beam multiplier of claim 1 wherein:

the beam-multiplying layer has a first index of refraction; and

the optical layer comprises an electro-optic layer having substantially the first index of refraction in response to a first electric field across the electro-optic layer and having a second index of refraction in response to a second electric field across the electro-optic layer.

12. The beam multiplier of claim 1 wherein:

the beam-multiplying layer has a first index of refraction; and

the optical layer comprises an electro-optic layer having substantially the first index of refraction in response to a nonzero electric field across the electro-optic layer and having a second index of refraction in response to a substantially zero electric field across the electro-optic layer.

13. The beam multiplier of claim 1, further comprising:

wherein the beam-multiplying layer has first and second opposite sides;

wherein the optical layer comprises an electro-optic layer having first and second opposite sides, the first side of the electro-optic layer adjacent to the second side of the beam-multiplying layer;

a first electrode adjacent to the first side of the beam-multiplying layer; and

a second electrode adjacent to the second side of the electro-optic layer.

14. The beam multiplier of claim 1, further comprising:

wherein the beam-multiplying layer has first and second opposite sides;

wherein the optical layer comprises an electro-optic layer having first and second opposite sides, the first side of the electro-optic layer adjacent to the second side of the beam-multiplying layer;

a first transparent electrode adjacent to the first side of the beam-multiplying layer; and

a second transparent electrode adjacent to the second side of the electro-optic layer.

15. The beam multiplier of claim 1, further comprising:

wherein the optical layer comprises an electro-optic layer having first and second opposite sides;

a first electrode disposed between the beam-multiplying layer and the first side of the electro-optic layer; and

a second electrode adjacent to the second side of the electro-optic layer.

16. The beam multiplier of claim 1, further comprising:

wherein the optical layer comprises an electro-optic layer having first and second opposite sides;

a first transparent electrode disposed between the beam-multiplying layer and the first side of the electro-optic layer; and

a second transparent electrode adjacent to the second side of the electro-optic layer.

17. A display system, comprising:

an image source operable to generate an optical source image; and

an exit-pupil expander operable to generate multiple exit-pupil images from the source image in response to a first signal and to generate only a single exit-pupil image in response to a second signal.

18. The display system of claim 17 wherein:

the first and second signals respectively comprises first and second electric fields; and

the exit-pupil expander comprises electrodes operable to apply the first and second electric fields across a portion of the exit-pupil expander.

19. The display system of claim 17 wherein the exit-pupil expander is further operable to:

generate a 0^th-order exit-pupil image and at least one higher-order exit-pupil image from the source image in response to the first signal; and

generate only the 0^th-order exit-pupil image from the source image in response to the second signal.

20. The display system of claim 17, further comprising a filter operable to attenuate one of the multiple exit-pupil images in response to the first signal and operable to pass the single exit-pupil image substantially unattenuated in response to the second signal.

21. A method, comprising:

generating beamlets from an incident light beam in response to a first stimulus; and

passing the incident light without generating the beamlets in response to a second stimulus.

22. The method of claim 21 wherein:

the first stimulus comprises a nonzero electric field; and

the second stimulus comprises a substantially zero electric field.

23. The method of claim 21 wherein:

the first stimulus comprises a first temperature; and

the second stimulus comprises a second temperature.

24. A method, comprising:

diffracting incident light in response to a first stimulus; and

passing the incident light substantially undiffracted in response to a second stimulus.

25. A method, comprising:

receiving an image with an exit-pupil expander;

generating multiple exit-pupil images from the received image when the exit-pupil expander is in a first state; and

generating a single exit-pupil image from the received image when the exit-pupil expander is in a second state.

26. The method of claim 25, further comprising:

causing the exit-pupil expander to be in the first state with a first stimulus; and

causing the exit-pupil expander to be in the second state with a second stimulus.

27. The method of claim 25, further comprising:

causing the exit-pupil expander to be in the first state by applying a first electric field across a portion of the exit-pupil expander; and

causing the exit-pupil expander to be in the second state by applying a second electric field across the portion of the exit-pupil expander.

28. The method of claim 25, further comprising:

causing the exit-pupil expander to be in the first state by taking a portion of the exit-pupil expander to a first temperature; and

causing the exit-pupil expander to be in the second state by taking the portion of the exit-pupil expander to a second temperature.

29. The method of claim 25, further comprising:

generating the image by sweeping an electromagnetic beam; and

wherein receiving the image comprises receiving the swept electromagnetic beam with the exit-pupil expander.

30. The method of claim 25 wherein generating multiple exit-pupil images comprises diffracting the received image.

31. The method of claim 25 wherein generating multiple exit-pupil images comprises refracting the received image.

32. The method of claim 25, further comprising:

causing the exit-pupil expander to be in the first state by causing a portion of the exit-pupil expander to have a first index of refraction; and

causing the exit-pupil expander to be in the second state by causing the portion of the exit-pupil expander to have a second index of refraction.

33. A method, comprising:

diffracting incident light according to a first diffraction property in response to a first stimulus; and

diffracting incident light according to a second diffraction property in response to a second stimulus.

34. The method of claim 33 wherein:

diffracting incident light according to the first diffraction property comprises generating outgoing light at an outgoing angle that is different than an incident angle of the incident light; and

diffracting the incident light according to the second diffraction property comprises generating outgoing light at an outgoing angle that is substantially the same as the incident angle of the incident light.

35. The method of claim 33 wherein:

the first stimulus comprises a first voltage; and

the second stimulus comprises a second voltage.

36. An optical device, comprising:

a diffraction grating having a diffraction characteristic; and

a structure operable to alter the diffraction characteristic of the diffraction grating.

37. The optical device of claim 36 wherein the structure comprises an electrode.

38. The optical device of claim 36 wherein the structure:

comprises first and second electrodes disposed on opposite sides of the diffraction grating; and

is operable to alter the diffraction characteristic of the diffraction grating in response to a voltage across the first and second electrodes.

39. The optical device of claim 36 wherein the structure:

comprises first and second electrodes disposed on a same side of the diffraction grating; and

is operable to alter the diffraction characteristic of the diffraction grating in response to a voltage across the first and second electrodes.

40. The optical device of claim 36 wherein the structure:

comprises first and second electrodes disposed on opposite sides of the diffraction grating; and

is operable to alter the diffraction characteristic of the diffraction grating in response to an electric field between the first and second electrodes.

41. The optical device of claim 36 wherein the structure:

comprises first and second electrodes disposed on a same side of the diffraction grating; and

is operable to alter the diffraction characteristic of the diffraction grating in response to an electric field between the first and second electrodes.

47. The optical device of claim 36 wherein the optical element comprises a refractive optical element.

48. The optical device of claim 36 wherein the optical element comprises an array of lenses.

49. The optical device of claim 36 wherein the optical element comprises a diffraction grating.

42. A method, comprising:

manipulating incident light according to a first optical characteristic in response to a first stimulus; and

manipulating incident light according to a second optical characteristic in response to a second stimulus.

43. The method of claim 42 wherein:

manipulating incident light according to the first optical characteristic comprises diffracting the incident light according to a first diffraction characteristic; and

manipulating the incident light according to the second optical characteristic comprises diffracting the incident light according to a first diffraction characteristic.

44. The method of claim 42 wherein:

manipulating incident light according to the first optical characteristic comprises refracting the incident light according to a first refraction characteristic; and

manipulating the incident light according to the second optical characteristic comprises refracting the incident light according to a first refraction characteristic.

45. An optical device, comprising:

an optical element having an optical characteristic; and

a structure operable to alter the optical characteristic of the optical element.

46. The optical device of claim 45 wherein the optical element comprises a diffractive optical element.

50. A method, comprising:

tuning an optical characteristic of an optical element with a stimulus; and

manipulating light with the tuned optical element.

51. The method of claim 50 wherein tuning an optical characteristic comprises tuning an index of refraction of the optical element with a stimulus.

52. The method of claim 50 wherein tuning an optical characteristic comprises tuning a refractive characteristic of the optical element with a stimulus.

53. The method of claim 50 wherein tuning an optical characteristic comprises tuning a diffractive characteristic of the optical element with a stimulus.

54. An optical element:

having an optical characteristic that is tunable in response to a stimulus; and

operable to manipulate light according to the tuned optical characteristic.

55. The optical element of claim 54 wherein the optical characteristic comprises a refractive characteristic.

56. The optical element of claim 54 wherein the optical characteristic comprises a diffractive characteristic.

57. The optical element of claim 54 wherein the optical characteristic comprises an index of refraction.