Method and system for tracking eye movement in conjunction with a light scanning projector
An eye tracking system includes a pair of glasses including two frames, a projector coupled to the pair of glasses and operable to project a beam of light, and an eyepiece mounted in one of the two frames and optically coupled to the projector. The eyepiece is operable to direct at least a portion of the beam of light towards an eye of a user. The eye tracking system also includes one or more optical sensors coupled to at least one of the two frames of the pair of glasses and operable to detect a set of reflected signals off the eye of the user, and a processor coupled to the projector and the one or more optical sensors, wherein the processor is operable to determine an eye orientation based on the set of reflected signals.
1. An eye tracking system comprising:
a pair of glasses including a first frame and a second frame, wherein the first frame includes a first periphery portion adjacent a first temple of a user and the second frame includes a second periphery portion adjacent a second temple of the user;
a first projector coupled to the first frame of the pair of glasses;
a second projector coupled to the second frame of the pair of glasses, wherein the first projector and the second projector are operable to project a beam of light;
a first eyepiece mounted in the first frame and optically coupled to the first projector, wherein the first eyepiece is operable to direct at least a first portion of the beam of light from the first projector towards a first eye of the user;
a second eyepiece mounted in the second frame and optically coupled to the second projector, wherein the second eyepiece is operable to direct at least a second portion of the beam of light from the second projector towards a second eye of the user;
a first optical sensor coupled to the first periphery portion, the first optical sensor being operable to detect a first set of reflected signals off the first eye of the user from the first portion of the beam of light from the first projector;
a second optical sensor coupled to the second periphery portion, the second optical sensor being operable to detect a second set of reflected signals off the second eye of the user from the second portion of the beam of light from the second projector; and
a processor coupled to the first projector, the second projector, the first optical sensor, and the second optical sensor, wherein the processor is operable to determine an orientation of the first eye and the second eye based on the first set of reflected signals and the second set of reflected signals.
2. The eye tracking system of claim 1 wherein:
the first eyepiece comprises:
a first inner surface facing the first eye of the user and a first outer surface opposing the first inner surface; and
a first diffractive structure overlaying the first eyepiece, wherein the first diffractive structure is formed as a first planar layer laminated to the first inner surface of the first eyepiece and is operable to diffract one or more time-varying reflected signals from the first eye to the first optical sensor; and
the second eyepiece comprises:
a second inner surface facing the second eye of the user and a second outer surface opposing the second inner surface; and
a second diffractive structure overlaying the second eyepiece, wherein the second diffractive structure is formed as a second planar layer laminated to the second inner surface of the second eyepiece and is operable to diffract one or more time-varying reflected signals from the second eye to the second optical sensor.
3. The eye tracking system of claim 1 wherein the first projector and the second projector each comprise a fiber scanning projector configured to scan in a spiral pattern with an increasing angular deflection as a function of time during a scanning time of an image frame.
4. The eye tracking system of claim 1 wherein the first eyepiece comprises a first plurality of planar waveguides, and wherein the second eyepiece comprises a second plurality of planar waveguides.
5. The eye tracking system of claim 4 wherein the first plurality of planar waveguides comprise four planar waveguides, and wherein the second plurality of planar waveguides comprise four planar waveguides.
6. The eye tracking system of claim 1 wherein the first optical sensor comprises a photodetector.
7. The eye tracking system of claim 1 wherein the beam of light corresponds to a display signal, wherein the first projector is further operable to output a first characterization signal, and wherein the second projector is further operable to output a second characterization signal.
8. The eye tracking system of claim 7 wherein the display signal comprises one or more visible wavelengths and the first characterization signal and the second characterization signal comprise one or more non-visible wavelengths.
9. The eye tracking system of claim 8 wherein the one or more visible wavelengths comprise red wavelengths, green wavelengths, and blue wavelengths and the one or more non-visible wavelengths comprise infrared wavelengths.
10. The eye tracking system of claim 1 wherein the first eyepiece comprises a plurality of planar waveguides including:
a first planar waveguide corresponding to red wavelengths;
a second planar waveguide corresponding to green wavelengths;
a third planar waveguide corresponding to blue wavelengths; and
a fourth planar waveguide corresponding to infrared wavelengths.
11. A method of operating an eye tracking system including a pair of glasses including a first frame and a second frame, a first projector coupled to the first frame, a second projector coupled to the second frame, a first eyepiece mounted in the first frame, a second eyepiece mounted in the second frame, a first optical sensor, and a second optical sensor, the method comprising:
generating, using the first projector and the second projector, an optical signal;
coupling at least a first portion of the optical signal into the first eyepiece;
coupling at least a second portion of the optical signal into the second eyepiece;
projecting, from the first eyepiece and the second eyepiece, an image viewable by a first eye and a second eye of a user;
reflecting, from the first eye of the user, a first set of reflected optical signals, wherein the first set of reflected optical signals corresponds to light related to the image reflected from the first eye of the user;
reflecting, from the second eye of the user, a second set of reflected optical signals, wherein the second set of reflected optical signals corresponds to light related to the image reflected from the second eye of the user;
detecting, using the first optical sensor, the first set of reflected optical signals, wherein the first optical sensor is coupled to a first periphery portion of the first frame adjacent a first temple of the user;
detecting, using the second optical sensor, the second set of reflected optical signals, wherein the second optical sensor is coupled to a second periphery portion of the second frame adjacent a second temple of the user; and
tracking a position of the first eye and the second eye of the user based on the first set of reflected optical signals and the second set of reflected optical signals.
12. The method of claim 11 , wherein the optical signal is a time-varying optical signal, wherein:
the first eyepiece includes:
a first inner surface facing the first eye of the user and a first outer surface opposing the first inner surface; and
a first diffractive structure overlaying the first eyepiece, wherein the first diffractive structure is formed as a first planar layer laminated to the first inner surface of the first eyepiece;
the second eyepiece includes:
a second inner surface facing the second eye of the user and a second outer surface opposing the second inner surface; and
a second diffractive structure overlaying the second eyepiece, wherein the second diffractive structure is formed as a second planar layer laminated to the second inner surface of the second eyepiece;
the first set of reflected optical signals comprises a first set of reflected time-varying optical signals and the second set of reflected optical signals comprises a second set of reflected time-varying optical signals, and wherein the method further comprises:
diffracting, using the first diffractive structure, the first set of reflected time-varying optical signals reflected off the first eye of the user to the first optical sensor; and
diffracting, using the second diffractive structure, the second set of reflected time-varying optical signals reflected off the second eye of the user to the second optical sensor.
13. The method of claim 11 wherein the first projector and the second projector each comprise a fiber scanning projector configured to scan in a spiral pattern with an increasing angular deflection as a function of time during a scanning time of the image.
14. The method of claim 11 wherein the optical signal comprises a display signal, and wherein the method further comprises:
generating, using the first projector, a first characterization signal; and
generating, using the second projector, a second characterization signal.
15. The method of claim 14 wherein the display signal comprises one or more visible wavelengths and the first characterization signal and the second characterization signal comprise one or more non-visible wavelengths.
16. The method of claim 15 wherein the one or more visible wavelengths comprise red wavelengths, green wavelengths, and blue wavelengths and the one or more non-visible wavelengths comprise infrared wavelengths.
17. The method of claim 11 wherein the first eyepiece comprises a first plurality of planar waveguides, and wherein the second eyepiece comprises a second plurality of planar waveguides.
18. The method of claim 17 wherein the first plurality of planar waveguides comprise four planar waveguides, and wherein the second plurality of planar waveguides comprise four planar waveguides.
19. The method of claim 11 wherein the first optical sensor comprises a photodetector.
20. The method of claim 11 wherein tracking the position of the first eye and the second eye of the user comprises:
correlating a position of a series of pixels of the image in the first eyepiece with a series of intensities of the first set of reflected optical signals from the first eye of the user; and
correlating a position of a series of pixels of the image in the second eyepiece with a series of intensities of the first set of reflected optical signals from the second eye of the user.