Holograghic waveguide eye tracker
An eye tracker having a first waveguide for propagating illumination light along a first waveguide path and propagating image light reflected from at least one surface of an eye along a second waveguide path. At least one grating lamina for deflecting the illumination light out of the first waveguide path towards the eye and deflecting the image light into the second waveguide path towards a detector is disposed adjacent an optical surface of the waveguide.
1. An apparatus for tracking the movement of an eye, comprising:
a first waveguide;
a light source for illuminating said eye;
at least one detector optically coupled to said waveguide; and
disposed within said waveguide, at least one grating layer comprising a first plurality of grating elements with a first prescription for diffracting a first characteristic of light reflected from said eye into a first total internal reflection (TIR) path to said detector and a second plurality of grating elements with a second prescription for diffracting a second characteristic of light reflected from said eye into a second TIR path to said detector.
2. The apparatus of claim 1 , wherein said first characteristic provides an image of said eye at said detector.
3. The apparatus of claim 1 , wherein said second characteristic provides an optical signature formed by at least one of reflection or scatter from at least one of an optical surface or ocular medium of said eye at said detector.
4. The apparatus of claim 3 , wherein said signature is one of speckle or glint.
5. The apparatus of claim 1 , wherein said first waveguide contains a grating or prism for coupling illumination from said source into an illumination TIR path in said first waveguide and a grating for coupling light out of said illumination TIR path onto said eye.
6. The apparatus of claim 1 , further comprising a second waveguide supporting a grating or prism for coupling illumination from said source into an illumination TIR path in said second waveguide and a grating for coupling light out of said illumination TIR path onto said eye.
7. The apparatus of claim 1 , wherein at least one of said first plurality of grating elements or said second plurality of grating elements comprises at least one switchable grating element having a diffracting state and a non-diffracting state.
8. The apparatus of claim 1 , wherein at least one of said first plurality of grating elements or said second plurality of grating elements comprises at least one switchable grating element having a diffracting state and a non-diffracting state, wherein said element in said diffracting state deflects light reflected from said eye into at least one of said first or second TIR paths.
9. The apparatus of claim 1 , wherein at least one of said first plurality of grating elements or said second plurality of grating elements comprises an array of elongate elements.
10. The apparatus of claim 1 , wherein at least one of said first plurality of grating elements or said second plurality of grating elements is a two-dimensional array.
11. The apparatus of claim 1 , wherein said grating layer comprises at least one of a switchable Bragg grating, a switchable grating recorded in a reverse mode holographic polymer dispersed liquid crystal, a switchable grating recorded in a reverse mode holographic polymer dispersed liquid crystal, a surface relief grating or a non-switching Bragg grating.
12. The apparatus of claim 1 , wherein said eye surface is at least one of a cornea, front or rear lens surface, iris, sclera or retina.
13. The apparatus of claim 1 , wherein said detector is a two-dimensional array.
14. The apparatus of claim 1 , further comprising at least one grating with at least one of optical power or diffusing properties.
15. The apparatus of claim 1 , wherein said detector is connected to at least one of an image processing apparatus for determining at least one spatio-temporal characteristic of an eye movement or an image processing system including a neural network.
16. The apparatus of claim 1 , wherein said detector is coupled to said waveguide by a grating or a prism.
17. The apparatus of claim 1 , integrated within a HMD or HUD.
18. The apparatus of claim 1 , further comprising a turning grating.
19. The apparatus of claim 1 , wherein said source is a laser or a light emitting diode.
20. The apparatus of claim 1 , wherein said at least one detector comprises a first detector for recording said first characteristic of light and a second detector for recording said second characteristic of light.