Scanning self-mixing interferometry with waveguide

Abstract

A light source of a self-mixed interferometer (SMI) emits infrared light. The infrared light is directed to an eyebox location with the scanning module by scanning the infrared light into a waveguide. Feedback infrared light is measured by a light sensor of the SMI.

What is claimed is: 
     
         1 . An eye-tracking device comprising:
 a self-mixed interferometer (SMI) including:
 an infrared light source including an optical cavity configured to emit infrared light; and 
 a light sensor optically coupled with the infrared light source; 
   a waveguide; and   a scanning module configured to scan the infrared light to the waveguide, wherein the waveguide is configured to direct the infrared light received from the scanning module to an eyebox location.   
     
     
         2 . The eye-tracking device of  claim 1 , wherein the waveguide includes an output grating to direct the infrared light received from the scanning module to the eyebox location. 
     
     
         3 . The eye-tracking device of  claim 2 , wherein the waveguide guides the infrared light to the output grating. 
     
     
         4 . The eye-tracking device of  claim 2 , wherein the waveguide includes a second output grating, and wherein the scanning module is configured to direct the infrared light to the second output grating to illuminate a second eyebox location. 
     
     
         5 . The eye-tracking device of  claim 4 , wherein the scanning module is configured to direct the infrared light to the second output grating during a second time period that is a subsequent to a first time period that the scanning module directs the infrared light to the output grating. 
     
     
         6 . The eye-tracking device of  claim 1 , wherein the light sensor of the SMI is configured to generate an SMI signal in response to feedback light entering the optical cavity of the infrared light source, the feedback light being a portion of the infrared light received back from the eyebox location. 
     
     
         7 . The eye-tracking device of  claim 6 , wherein the waveguide includes an output grating to direct the infrared light received from the scanning module to the eyebox location, and wherein the feedback light propagates through the output grating, through the waveguide, reflects off a reflective element of the scanning module, and then enters the optical cavity of the infrared light source of the SMI. 
     
     
         8 . The eye-tracking device of  claim 1 , wherein the scanning module includes a reflective element and the SMI is configured to point the infrared light to the reflective element of the scanning module, and wherein the scanning module is configured to direct the infrared light to the eyebox location by adjusting the reflective element to redirect the infrared light emitted by the infrared light source of the SMI to the eyebox location. 
     
     
         9 . The eye-tracking device of  claim 1 , wherein the scanning module is configured to direct the infrared light to  120  or more eyebox locations per second. 
     
     
         10 . The eye-tracking device of  claim 1 , wherein the light sensor of the SMI is configured to generate an SMI signal in response to feedback light entering the optical cavity of the infrared light source, the eye-tracking device further comprising:
 processing logic configured to receive the SMI signal from the light sensor, wherein the processing logic is further configured to generate eye data that includes depth or velocity measurements of an eye when an eye is present in an eyebox.   
     
     
         11 . The eye-tracking device of  claim 10 , wherein the processing logic is configured to receive eye image data from a camera positioned to image the eye, and wherein the eye data generated by the processing logic is generated in response to the SMI signal and the eye image data. 
     
     
         12 . The eye-tracking device of  claim 1 , wherein waveguide includes a refractive material. 
     
     
         13 . A sensor comprising:
 a self-mixed interferometer (SMI) including a light source configured to emit coherent light;   a scanning module configured to direct the coherent light to a plurality of target locations, wherein the SMI also includes a light sensor configured to generate a plurality of SMI signals in response to feedback light received back from the plurality of target locations; and   a waveguide configured to receive the coherent light from the scanning module, wherein the waveguide includes a first output grating to direct the coherent light to a first target location in the plurality of target locations, and wherein the scanning module is also configured to direct the coherent light a second output grating of the waveguide illuminate a second target location in the plurality of target locations.   
     
     
         14 . The sensor of  claim 13 , wherein the scanning module is configured to direct the coherent light to a second target location, wherein the light sensor of the SMI is configured to generate a second SMI signal in response to second feedback light entering an optical cavity of the light source, the second feedback light being a portion of the coherent light received back from the second target location. 
     
     
         15 . The sensor of  claim 13  further comprising:
 processing logic configured to receive the SMI signals from the light sensor, wherein the processing logic is further configured to generate eye data that includes depth or velocity measurements of an eye when an eye is present in an eyebox. 
 
     
     
         16 . The sensor of  claim 15 , wherein the processing logic is configured to receive eye image data from a camera positioned to image the eye, and wherein the eye data generated by the processing logic is generated in response to the SMI signals and the eye image data. 
     
     
         17 . The sensor of  claim 13 , wherein the scanning module is configured to direct the coherent light to a second target location during a second time period that is a subsequent to a first time period that the scanning module directs the coherent light to the target locations. 
     
     
         18 . The sensor of  claim 13 , wherein the scanning module is configured to direct the coherent light to 120 or more eyebox locations per second. 
     
     
         19 . A method of eye-tracking comprising:
 activating an infrared light source of a self-mixed interferometer (SMI) to emit coherent infrared light;   directing the coherent infrared light to an eyebox location with a scanning module, wherein directing the coherent infrared light to the eyebox location includes scanning the coherent infrared light into a waveguide; and   measuring an SMI signal generated by the SMI in response to feedback infrared light received back from the eyebox location, wherein the feedback infrared light is a portion of the coherent infrared light.   
     
     
         20 . The method of  claim 19 , wherein the waveguide includes an output grating to direct the coherent infrared light received from the scanning module to the eyebox location.