Virtual and augmented reality systems and methods having improved diffractive grating structures

• US 10,466,486 B2
• Filed: 02/14/2018
• Issued: 11/05/2019
• Est. Priority Date: 01/26/2015
• Status: Active Grant

• Current Assignee: Magic Leap, Inc.
• Original Assignee: Magic Leap, Inc.
• Inventors: Tekolste, Robert D., Klug, Michael A., Greco, Paul M., Schowengerdt, Brian T.
• Primary Examiner(s): Lett, Thomas J
• Application Number:
  US15/896,438
• Publication Number:
  US 20180172998A1
• Time in Patent Office: 629 Days
• CPC Class Codes: G02B 2027/0105 Holograms with particular structures
• CPC Class Codes: G02B 2027/0107 with optical power
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/4205 having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955
• CPC Class Codes: G02B 5/1842 Gratings for image generation G02B5/1847 takes precedence
• CPC Class Codes: G02B 6/0011 the light guides being planar or of plate-like form
• CPC Class Codes: G06T 19/006 Mixed reality object pose determination, tracking or camera calibration for mixed reality G06T7/00

Abstract

Disclosed is an improved diffraction structure for 3D display systems. The improved diffraction structure includes an intermediate layer that resides between a waveguide substrate and a top grating surface. The top grating surface comprises a first material that corresponds to a first refractive index value, the underlayer comprises a second material that corresponds to a second refractive index value, and the substrate comprises a third material that corresponds to a third refractive index value.

Claims

1. An augmented reality (AR) display system for delivering augmented reality content to a user, comprising:

an image-generating source to provide one or more frames of image data;

a light modulator to transmit light associated with the one or more frames of image data;

a diffractive optical element (DOE) to receive the light associated with the one or more frames of image data and direct the light to the user'"'"'s eyes, the DOE comprising a diffraction structure having a waveguide substrate, a surface grating, and an underlayer disposed between the waveguide substrate and the surface grating; and

wherein the surface grating has a surface grating refractive index, the underlayer has an underlayer refractive index, and the surface grating refractive index is smaller than the underlayer refractive index.

2. The system of claim 1, wherein the underlayer refractive index is approximately 1.79 or 1.84.

3. The system of claim 1, wherein the waveguide substrate has a waveguide substrate refractive index, and the waveguide substrate refractive index is approximately 1.5, 1.7, or 1.8.

4. The system of claim 1, wherein all of the waveguide substrate, the underlayer, and the surface grating correspond to different refractive index values.

5. The system of claim 1, wherein the underlayer refractive index is higher value compared to a waveguide refractive index.

6. The system of claim 1, wherein the waveguide substrate, the underlayer, and the surface grating correspond to different materials.

7. The system of claim 1, wherein at least two of the waveguide substrate, the underlayer, and the surface grating correspond to a common refractive index value.

8. The system of claim 7, wherein the at least two of the waveguide substrate, the underlayer, and the surface grating correspond to the same material.

9. The system of claim 1, wherein the underlayer comprises a non-uniform thickness.

10. The system of claim 9, wherein the non-uniform thickness of the underlayer changes from a relatively thin to a relatively thick as distance is increased from a light injection location.

11. The system of claim 1, wherein the underlayer comprises a non-uniform underlayer refractive index.

12. The system of claim 11, wherein the non-uniform underlayer refractive index of the underlayer changes from being relatively similar to the waveguide refractive index to being increasing different from the waveguide refractive index as distance is increased from a light injection location.

13. The system of claim 1, wherein the underlayer comprises both a non-uniform thickness and a non-uniform underlayer refractive index.

14. The system of claim 1, wherein the system comprises a stacked waveguide assembly having a plurality of the diffraction structure that are stacked together.

15. The system of claim 14, wherein a plurality of the image-generating source injects the image data into each of the diffraction structure within the stacked waveguide assembly.

16. The system of claim 1, wherein the waveguide substrate, the underlayer, and the surface grating correspond to at least one of polymer material, sapphire, or glass.

17. The system of claim 1, wherein the DOE is switchable between an ON state and an OFF state.

18. The system of claim 1, embodied as a head-mountable wearable system.

19. The system of claim 1, where the diffraction structure further comprises a top surface layer over the surface grating.

20. The system of claim 19, wherein the top surface layer forms an interstitial layer for stacking of the diffraction structure, and the top surface layer has an index of refraction of around 1.1 to 1.2.

21. The system of claim 19, wherein the top surface layer has an index of refraction of around 1.86.

22. The system of claim 1, wherein the surface grating refractive index is approximately 1.5 or 1.86.