Eye tracking and gaze fixation detection systems, components and methods using polarized light

Patent metadata

Field	Value
Publication number	US-9737209-B2
Application number	US-201414889401-A
Country	US
Kind code	B2
Filing date	May 15, 2014
Priority date	May 15, 2013
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

An eye tracking and gaze fixation detection system, includes an electronically scannable optical illumination system emits polarized near-infrared (NIR) light to a retina in an eye of a subject; an optical detection system arranged in an optical path of the NIR light after being reflected from the retina of the eye of the subject, the optical detection system providing a detection signal; and a signal processing system communicates with the optical detection system to receive the detection signal, wherein the optical illumination system emits the polarized NIR light to illuminate at least a portion of a scanning path, wherein the scanning path is a spatially closed loop across a portion of the retina in the eye of the subject that repeats periodically over time, and wherein the signal processing system is configured to determine at least one of a gaze direction and a gaze fixation based on the detection signal.

First claim

We claim:

1. An eye tracking and gaze fixation detection system, comprising:
an electronically scannable optical illumination system arranged to emit polarized near-infrared (NIR) light to at least a portion of a retina in an eye of a subject;
an optical detection system arranged in an optical path of said NIR light after being reflected from the retina of the eye of the subject, said optical detection system providing a detection signal; and
a signal processing system configured to communicate with the optical detection system to receive said detection signal,
wherein the optical illumination system is configured to emit the polarized NIR light to illuminate at least a portion of a scanning path,
wherein said scanning path is a spatially closed loop across a portion of said retina in said eye of said subject that repeats periodically over time, and
wherein the signal processing system is configured to determine at least one of a gaze direction and a gaze fixation based on the detection signal.

2. The eye tracking and gaze fixation detection system of claim 1 , wherein the electronically scannable optical illumination system comprises a plurality of emitters that are electronically addressable to emit in a timed sequence corresponding to portions of said scanning path.

3. The eye tracking and gaze fixation detection system of claim 2 , wherein the optical detection system comprises a plurality of polarization-sensitive detectors arranged at least one of substantially coincident with or optically conjugate with a corresponding one of the plurality of emitters to detect the at least one polarization component of reflected near-infrared light from the retina of the eye of the subject.

4. The eye tracking and gaze fixation detection system according to claim 3 , wherein the optical detection system comprises a liquid crystal polarization rotator,
wherein the liquid crystal polarization rotator is configured to rotate the detected polarization component.

5. The eye tracking and gaze fixation detection system of claim 3 , wherein the plurality of emitters and the plurality of detectors are positioned outside a periphery of a screen that is adapted for the subject to gaze at.

6. The eye tracking and gaze fixation detection system according to claim 3 , wherein the plurality of detectors comprises an image sensor array.

7. The eye tracking and gaze fixation detection system of claim 2 , wherein each of the plurality of emitters comprises a laser diode.

8. The eye tracking and gaze fixation detection system according to claim 7 , wherein each of the plurality of laser diodes is one of at least an edge-emitting laser diode or a vertical cavity surface emitting laser diode.

9. The eye tracking and gaze fixation detection system according to claim 7 , wherein said electronically scannable optical illumination system further comprises a liquid crystal polarization rotator arranged to rotate the plane of polarization of the light from said plurality of laser diodes to enhance said detection signal.

10. The eye tracking and gaze fixation detection system according to claim 7 , wherein said electronically scannable optical illumination system further comprises a plurality of optical fibers, and
wherein each optical fiber of said plurality of optical fibers is optically coupled to a corresponding one of said plurality of laser diodes.

11. The eye tracking and gaze fixation detection system according to claim 2 , wherein the optical detection system comprises a plurality of photodetectors arranged to substantially surround each of the plurality of emitters in a plane substantially common to the location of both the emitters and the detectors.

12. The eye tracking and gaze fixation detection system according to claim 2 , wherein the electronically scannable optical illumination system comprises a laser diode coupled to an optical multiplexer, and
wherein the optical multiplexer is optically coupled to each of the plurality of emitters.

13. The eye tracking and gaze fixation detection system according to claim 2 , wherein each of the plurality of emitters comprises a light-emitting diode, and
wherein the electronically scannable optical illumination system further comprises a polarizer disposed in an optical path between the emitters and the subject.

14. The eye tracking and gaze fixation detection system according to claim 13 , wherein the electronically scannable optical illumination system comprises an optical multiplexer that is optically coupled to each of the plurality of emitters.

15. The eye tracking and gaze fixation detection system of claim 2 , wherein said timed sequence of said plurality of emitters is determined by electronically addressable liquid crystal shutters arrayed before said emitters that allow emission of the NIR light of the emitter through the electronically addressable liquid crystal shutters in said sequence.

16. The eye tracking and gaze fixation detection system of claim 1 , wherein the electronically scannable optical illumination system comprises an emitter that is arranged to continuously emit NIR light in a timed sequence, and said timed sequence of emission of said emitter being determined by electronically addressable liquid crystal shutters arrayed before said emitter that allows emission of the NIR light of the emitter through the electronically addressable liquid crystal shutters in said sequence.

17. The eye tracking and gaze fixation detection system of claim 1 , wherein said electronically scannable optical illumination system comprises:
a digital micromirror device comprising a plurality of micromirrors, and
an emitter of NIR light arranged to illuminate at least a portion of said digital micromirror device,
wherein the plurality of micromirrors are configured to have electronically addressable ON and OFF states to provide a timed sequence of NIR light corresponding to at least a portion of said scanning path.

18. The eye tracking and gaze fixation detection system of claim 1 , further comprising a display that is adapted to be viewed by the subject,
wherein said electronically scannable optical illumination system and said optical detection system are integrated into a viewing region of said display.

19. The eye tracking and gaze fixation detection system according to claim 1 , further comprising a variable liquid crystal retarder arranged in the optical path of the NIR light from the electronically scannable optical illumination system after being reflected from the object of interest prior to being detected by the optical detection system.

20. The eye tracking and gaze fixation detection system according to claim 19 , wherein the variable liquid crystal retarder is electrically controllable by a central processing unit.

21. The eye tracking and gaze fixation detection system according to claim 1 , further comprising an interference filter arranged in the optical path of the NIR light from the electronically scannable optical illumination system after being reflected from the eye of the subject prior to being detected by the optical detection system.

22. The eye tracking and gaze fixation detection system according to claim 1 , wherein said electronically scannable optical illumination system and said optical detection system comprise a polarization-sensitive optical transducer, said polarization-sensitive optical transducer comprising:
a source of polarized light that has an end portion arranged to project the polarized light;
a photodete

Assignees

• Univ Johns Hopkins

Inventors

• Gramatikov Boris I
• Guyton David L
• Irsch Kristina

Classifications

• G02F1/1313

  specially adapted for a particular application · CPC title

• G02B26/0833

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · CPC title

• A61B3/0008

  provided with illuminating means (A61B3/117, A61B3/14 take precedence) · CPC title

• G01N21/23

  Bi-refringence · CPC title

• A61B3/0025

  characterised by electronic signal processing, e.g. eye models · CPC title