Eye-tracker illumination

Abstract

A subject is illuminated whose movements of at least one eye are to be registered by an eye-tracker for producing resulting data. To this aim, a coherent light source in light producing means produces at least one well-defined light beam. A diffractive optical element is arranged between the coherent light source and an output from the light producing means. The diffractive optical element is configured to direct a light beam towards at least a first designated area estimated to cover the at least one eye of the subject. Image registering means registers light from the at least one light beam having been reflected against the subject. The resulting data is produced in response to these light reflections, which resulting data represents movements of the at least one eye of the subject.

1 . (canceled) 
     
     
         2 . A system for determining a gaze direction, the system comprising:
 an eye tracking device including:
 a light source configured to produce coherent light; 
 a light redirection device configured to adaptively direct a portion of the coherent light towards a first eye of a user, wherein the light redirection device comprises a diffractive element; and 
 an image sensor configured to detect a glint on the first eye caused by the portion of the coherent light reflecting off the first eye of the user. 
   
     
     
         3 . The system of  claim 2 , wherein the light redirection device further comprises:
 a refractive element.   
     
     
         4 . The system of  claim 2 , wherein the light redirection device further comprises:
 a reflective element.   
     
     
         5 . The system of  claim 2 , wherein the light redirection device being configured to adaptively direct the portion of the coherent light towards the first eye comprises the light redirection device being configured to:
 redirect the coherent light to a first designated area estimated to comprise the first eye; and   adaptively control a location of the first designated area such that the first designated area is estimated to comprise the first eye over time.   
     
     
         6 . The system of  claim 5 , wherein the light redirection device being configured to adaptively direct the portion of the coherent light towards the first eye further comprises the light redirection device being configured to:
 redirect the coherent light to a second designated area, wherein the second designated area is estimated to comprise a second eye of the user; and   adaptively control a location of the second designated area such that the second designated area is estimated to comprise the second eye over time.   
     
     
         7 . The system of  claim 6 , wherein the image sensor is further configured to:
 detect a glint on the second eye caused by the portion of the coherent light reflecting off the second eye.   
     
     
         8 . The system of  claim 7 , wherein the system further comprises:
 one or more processors configured to:
 determine a gaze direction of the user based on the glint on the first eye and the glint on the second eye. 
   
     
     
         9 . A non-transitory computer readable medium having instructions stored thereon executable by a computing device to cause the computing device to perform operations comprising:
 producing coherent light;   redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise a first eye of the user; and   detecting, with an image sensor, a glint on the first eye caused by the coherent light reflecting off the first eye.   
     
     
         10 . The non-transitory computer readable medium of  claim 9 , wherein redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise a first eye comprises:
 adaptively controlling a location of the first designated area such that the first eye is maintained within the first designated area.   
     
     
         11 . The non-transitory computer readable medium of  claim 9 , wherein the first optical element further comprises:
 a lens to alter the coherent light and thereby change a property of the first designated area.   
     
     
         12 . The non-transitory computer readable medium of  claim 9 , wherein redirecting the coherent light comprises:
 redirecting the coherent light with a second optical element configured to adaptively redirect the coherent light towards a second designated area of a user estimated to comprise a second eye of the user.   
     
     
         13 . The non-transitory computer readable medium of  claim 12 , wherein redirecting the coherent light further comprises:
 time modulating the first optical element and the second optical element such that the first designated area and the second designated area are illuminated alternately.   
     
     
         14 . The non-transitory computer readable medium of  claim 12 , wherein the first optical element comprises:
 a first filter to allow coherent light of a first wavelength to pass through the first optical element; and   a second filter to allow coherent light of a second wavelength to pass through the second optical element.   
     
     
         15 . The non-transitory computer readable medium of  claim 9 , wherein detecting, with an image sensor, a glint on the first eye produced in response to the coherent light reflecting off the first eye comprises:
 determining a restricted portion of the image sensor capable of detecting the glint on the first eye; and   detecting, using only the restricted portion of the image sensor, the glint on the first eye.   
     
     
         16 . A method for illuminating an eye of a user for use with an eye tracking device, the method comprising:
 producing coherent light;   redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise a first eye of the user;   detecting, with an image sensor, a glint on the first eye caused by the coherent light reflecting against the first eye; and   determining a gaze direction of the user based on the glint.   
     
     
         17 . The method of  claim 16 , wherein redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise a first eye comprises:
 adaptively controlling the first designated area to maintain the first eye within the first designated area over time.   
     
     
         18 . The method of  claim 17 , wherein redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise a first eye further comprises:
 redirecting the coherent light towards a second designated area of the user estimated to comprise a second eye of the user using a second optical element; and   adaptively controlling the second designated area to maintain the second eye within the second designated area over time.   
     
     
         19 . The method of  claim 18 , wherein redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise the first eye comprises:
 redirecting, in a time alternated manner, the coherent light towards the first optical element and the second optical element.   
     
     
         20 . The method of  claim 16 , wherein redirecting the coherent light with a first optical element configured to adaptively redirect the coherent light towards a first designated area of a user estimated to comprise the first eye further comprises:
 shaping and controlling a direction of the coherent light using a lens element.   
     
     
         21 . The method of  claim 16 , wherein producing the coherent light comprises:
 time-modulating the coherent light to produce the coherent light with a temporally varying speckle pattern.