Waveguide

• US 9,513,480 B2
• Filed: 02/09/2015
• Issued: 12/06/2016
• Est. Priority Date: 02/09/2015
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Saarikko, Pasi, Kostamo, Pasi
• Primary Examiner(s): KIM, ELLEN E
• Application Number:
  US14/617,697
• Publication Number:
  US 20160231568A1
• Time in Patent Office: 666 Days
• Field of Search: 385/31, 385/37, 349/65, 359/630, 359/34, 359/571, 359/633, 345/690
• US Class Current: 1/1
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/4272 having plural diffractive elements positioned sequentially along the optical path
• CPC Class Codes: G02B 5/1842 Gratings for image generation G02B5/1847 takes precedence
• CPC Class Codes: G02B 5/1861 Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0033 Means for improving the coupling-out of light from the light guide
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it

Abstract

A waveguide has a front and a rear surface, the waveguide for a display system and arranged to guide light from a light engine onto an eye of a user to make an image visible to the user, the light guided through the waveguide by reflection at the front and rear surfaces. A first portion of the front or rear surface has a structure which causes light to change phase upon reflection from the first portion by a first amount. A second portion of the same surface has a different structure which causes light to change phase upon reflection from the second portion by a second amount different from the first amount. The first portion is offset from the second portion by a distance which substantially matches the difference between the second amount and the first amount.

Claims

1. A waveguide having a front and a rear surface, the waveguide for a display system and arranged to guide light from a light engine onto an eye of a user to make an image visible to the user, the light guided through the waveguide by reflection at the front and rear surfaces;

wherein a first portion of the front or rear surface has a structure which causes light to change phase upon reflection from the first portion by a first amount;

wherein a second portion of the same surface has a different structure which causes light to change phase upon reflection from the second portion by a second amount different from the first amount; and

wherein the first portion is offset from the second portion by a distance which substantially matches the difference between the second amount and the first amount.

2. A waveguide according to claim 1 wherein the structure of the first portion constitutes a first diffraction grating.

3. A waveguide according to claim 2 wherein the structure of the second portion constitutes a second diffraction grating.

4. A waveguide according to claim 3 wherein the first grating has a depth different from the second grating.

5. A waveguide according to claim 2 wherein the first grating has a depth which is substantially constant over the entire first portion up to the edge of the first grating.

6. A waveguide according to claim 3 wherein the first grating has a depth which is substantially constant over the entire first portion up to the edge of the first grating, and the second grating has a depth which is substantially constant over the entire second portion up to the edge of the second grating.

7. A waveguide according to claim 1 wherein the structure of the first portion constitutes a first diffraction grating and the structure of the second portion is substantially non-diffractive.

8. A waveguide according to claim 7 wherein the first grating has a depth which is substantially constant over the entire first portion up to the edge of the first grating.

9. A waveguide according to claim 1 wherein the first and second portions are substantially contiguous.

10. A waveguide according to claim 9, wherein the first and second portions are separated by no more than 100 micrometers in width along a common border, and optionally no more than 50 micrometers in width along the common border.

11. A waveguide according to claim 1 wherein a third portion of the same surface has a structure which causes light to change phase upon reflection from the third portion by a third amount different from the first amount, wherein the first and third portions are adjacent the second portion so that the second portion separates the first and third portions, and wherein the third portion is offset from the second portion by a distance which substantially matches the difference between the second amount and the third amount.

12. A waveguide according to claim 11 wherein the structure of the first portion constitutes a first diffraction grating, the structure of the third portion constitutes a second diffraction grating, and the structure of the second portion is substantially non-diffractive.

13. An image display system comprising:

a light engine configured to generate an image;

a waveguide having a front and a rear surface, the waveguide arranged to guide light from the light engine onto an eye of a user to make the image visible to the user, the light guided through the waveguide by reflection at the front and rear surfaces, wherein a first portion of the front or rear surface has a structure which causes light to change phase upon reflection from the first portion by a first amount, wherein a second portion of the same surface has a different structure which causes light to change phase upon reflection from the second portion by a second amount different from the first amount, and wherein the first portion is offset from the second portion by a distance which substantially matches the difference between the second amount and the first amount.

14. A display system according to claim 13 wherein the structure of the first portion constitutes an incoupling grating via which said light is coupled into the waveguide from the display.

15. A display system according to claim 13 wherein the structure of the second portion constitutes an exit grating via which said light exits the waveguide onto the eye of the user.

16. A display system according to claim 13 wherein the structure of the second portion constitutes an intermediate grating configured to manipulate the spatial distribution of the light within the waveguide.

17. A wearable image display system comprising:

a headpiece;

a light engine mounted on the headpiece and configured to generate an image;

a waveguide located forward of an eye of a wearer in use, the waveguide having a front and a rear surface, the waveguide arranged to guide light from the light engine onto the eye of the wearer to make the image visible to the wearer, the light guided through the waveguide by reflection at the front and rear surfaces, wherein a first portion of the front or rear surface has a structure which causes light to change phase upon reflection from the first portion by a first amount, wherein a second portion of the same surface has a different structure which causes light to change phase upon reflection from the second portion by a second amount different from the first amount, and wherein the first portion is offset from the second portion by a distance which substantially matches the difference between the second amount and the first amount.

18. A display system according to claim 17 wherein the structure of the first portion constitutes an incoupling grating via which said light is coupled into the waveguide from the display.

19. A display system according to claim 17 wherein the structure of the second portion constitutes an exit grating via which said light exits the waveguide onto the eye of the user.

20. A display system according to claim 17 wherein the structure of the second portion constitutes an intermediate grating configured to manipulate the spatial distribution of the light within the waveguide.