Apparatus for eye tracking

• US 9,804,389 B2
• Filed: 09/23/2016
• Issued: 10/31/2017
• Est. Priority Date: 05/11/2012
• Status: Active Grant

• Current Assignee: DigiLens Inc
• Original Assignee: DigiLens Inc
• Inventors: Popovich, Milan Momcilo, Waldern, Jonathan David, Grant, Alastair John
• Primary Examiner(s): DANG, HUNG XUAN
• Application Number:
  US15/274,049
• Publication Number:
  US 20170031160A1
• Time in Patent Office: 403 Days
• Field of Search: 351221, 351209, 351210
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0174 holographic
• 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 27/0093 with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/4287 Optical modules with tapping or launching means through the surface of the waveguide G02B6/2852, G02B6/4286 take precedence
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 1/294 Variable focal length devices
• CPC Class Codes: G02F 1/2955 by controlled diffraction or phased-array beam steering controlled diffraction for optical waveguide switching G02F1/313
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 2201/16 series; tandem
• CPC Class Codes: G02F 2201/30 grating
• CPC Class Codes: G02F 2201/302 grating coupler
• CPC Class Codes: G02F 2201/305 : diffraction grating
• CPC Class Codes: G02F 2201/307 : Reflective grating, i.e. Bragg grating
• CPC Class Codes: G02F 2203/24 : beam steering
• CPC Class Codes: G02F 2203/28 : focussing or defocussing
• CPC Class Codes: G02F 2203/62 : Switchable arrangements whereby the element being usually not switchable
• CPC Class Codes: G06V 40/193 : Preprocessing; Feature extraction
• CPC Class Codes: H04N 5/33 : Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An eye tracker having a waveguide for propagating illumination light towards an eye and propagating image light reflected from at least one surface of an eye, a light source optically coupled to the waveguide, and a detector optically coupled to the waveguide. Disposed in the waveguide is at least one grating lamina for deflecting the illumination light towards the eye along a first waveguide path and deflecting the image light towards the detector along a second waveguide path.

Claims

1. An eye tracker comprising:

a source, a detector; and

a waveguiding structure comprising a first waveguide containing an input coupler for coupling illumination from said source into a first TIR waveguide path in said first waveguide and a first grating for coupling light out of said first TIR waveguide path onto an eye; and

a second waveguide containing a second grating for coupling light reflected from at least one surface of eye into a second TIR waveguide path in said second waveguide and an output coupler for coupling light out of said second TIR path onto said detector.

2. The apparatus of claim 1 wherein said first and second waveguide are formed as a single continuous waveguide layer.

3. The apparatus of claim 1 wherein said first and second waveguide are configured as separate overlapping waveguide layers wherein first grating at least partially overlaps said second grating.

4. The apparatus of claim 1 wherein said second grating comprises a multiplicity of electrically switchable elements each having a diffracting state for coupling light from said eye into said waveguide and a non-diffracting state.

5. The apparatus of claim 1 wherein said first and second waveguide paths are in opposing directions.

6. The apparatus of claim 1 wherein said first grating is disposed in proximity to an upper or lower edge of said second grating along said first waveguide path.

7. The apparatus of claim 1 wherein said first grating comprises first and second gratings disposed in proximity to upper and lower edges of said second grating along said first waveguide path.

8. The apparatus of claim 1 wherein said input coupler is one of a grating or a prism.

9. The apparatus of claim 1 wherein said output coupler is one of a grating or a prism.

10. The apparatus of claim 1 wherein said first grating is a linear array of elongate switchable beam deflection elements with longer dimension aligned perpendicular to said first waveguide path.

11. The apparatus of claim 1 wherein said second grating is a linear array of elongate switchable beam deflection elements with longer dimension aligned perpendicular to said second waveguide path.

12. The apparatus of claim 1 wherein each said grating is one of a switchable Bragg grating, a switchable grating recorded in a reverse mode holographic polymer dispersed liquid crystal, or a non-switching Bragg grating.

13. The apparatus of claim 1 wherein said light reflected from said eye is speckle.

14. The apparatus of claim 1 wherein said eye surface is at least one of the cornea, lens, iris, sclera and retina.

15. The apparatus of claim 1 wherein said detector is a two-dimensional array.

16. The apparatus of claim 1 wherein said first grating encodes optical power.

17. The apparatus of claim 1 wherein said second grating encodes optical power.

18. The apparatus of claim 1 wherein said detector is connected to an image processing apparatus for determining at least one spatio-temporal characteristic of an eye movement.

19. The apparatus of claim 1 wherein said first grating encodes diffusing properties.

20. The apparatus of claim 1 wherein said source is in the infrared band.