Systems, devices, and methods for eyebox expansion in wearable heads-up displays

Abstract

Systems, devices, and methods for eyebox expansion by exit pupil replication in scanning laser-based wearable heads-up displays (“WHUDs”) are described. The WHUDs described herein each include a scanning laser projector (“SLP”), a holographic combiner, and an optical replicator positioned in the optical path therebetween. For each light signal generated by the SLP, the optical replicator receives the light signal and redirects each one of N>1 instances of the light signal towards the holographic combiner effectively from a respective one of N spatially-separated virtual positions for the SLP. The holographic combiner converges each one of the N instances of the light signal to a respective one of N spatially-separated exit pupils at the eye of the user. In this way, multiple instances of the exit pupil are distributed over the area of the eye and the eyebox of the WHUD is expanded.

1 . A method of operating a wearable heads-up display, the wearable heads-up display including a scanning laser projector, an optical replicator, and a holographic combiner positioned within a field of view of an eye of a user when the wearable heads-up display is worn on a head of the user, the method comprising:
 generating a first light signal by the scanning laser projector;   redirecting respective ones of N instances of the first light signal towards the holographic combiner by the optical replicator, where N is an integer greater than 1; and   redirecting each instance of the first light signal that is received from the optical replicator towards the eye of the user by the holographic combiner.   
     
     
         2 . The method of  claim 1 , further comprising:
 receiving the first light signal from the scanning laser projector by the optical replicator; and   replicating the first light signal into the N instances of the first light signal by the optical replicator.   
     
     
         3 . The method of  claim 1  wherein redirecting each instance of the first light signal that is received from the optical replicator towards the eye of the user by the holographic combiner includes redirecting each instance of the first light signal that is received from the optical replicator spatially in parallel with one another towards respective regions of the eye of the user by the holographic combiner. 
     
     
         4 . The method of  claim 1  wherein redirecting respective ones of N instances of the first light signal towards the holographic combiner by the optical replicator includes redirecting respective ones of N instances of the first light signal towards the holographic combiner by the optical replicator effectively from respective ones of N spatially-separated virtual positions for the scanning laser projector. 
     
     
         5 . The method of  claim 1  wherein redirecting each instance of the first light signal that is received from the optical replicator towards the eye of the user by the holographic combiner includes converging each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the holographic combiner. 
     
     
         6 . The method of  claim 5  wherein the holographic combiner includes at least two multiplexed holograms, and wherein converging each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the holographic combiner includes converging each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by a respective multiplexed hologram. 
     
     
         7 . The method of  claim 6  wherein:
 the scanning laser projector includes a red laser diode, a green laser diode, and a blue laser diode; 
 the first light signal generated by the scanning laser projector includes a red component, a green component, and a blue component; and 
 the holographic combiner includes a wavelength-multiplexed holographic combiner that includes at least one red hologram, at least one green hologram, and at least one blue hologram, and wherein converging each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by a respective multiplexed hologram includes: 
 converging a respective red component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the at least one red hologram; 
 converging a respective green component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the at least one green hologram; and 
 converging a respective blue component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the at least one blue hologram. 
 
     
     
         8 . The method of  claim 7  wherein the holographic combiner includes a wavelength-multiplexed and angle-multiplexed holographic combiner that includes at least two angle-multiplexed red holograms, at least two angle-multiplexed green holograms, and at least two angle-multiplexed blue holograms, and wherein:
 converging a respective red component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the at least one red hologram includes converging a respective red component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by a respective angle-multiplexed red hologram; 
 converging a respective green component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the at least one green hologram includes converging a respective green component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by a respective angle-multiplexed green hologram; and 
 converging a respective blue component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the at least one blue hologram includes converging a respective blue component of each instance of the first light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by a respective angle-multiplexed blue hologram. 
 
     
     
         9 . The method of  claim 1 , further comprising:
 generating at least a second light signal by the scanning laser projector;   redirecting respective ones of N instances of the at least a second light signal towards the holographic combiner by the optical replicator; and   converging each instance of the at least a second light signal that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the holographic combiner.   
     
     
         10 . The method of  claim 1 , further comprising:
 generating light signals corresponding to a sweep of a total scan range θ by the scanning laser projector;   receiving the light signals corresponding to the total scan range θ of the scanning laser projector by the optical replicator;   redirecting respective ones of N instances of the total scan range θ of the scanning laser projector towards the holographic combiner by the optical replicator; and   converging each instance of the total scan range θ of the scanning laser projector that is received from the optical replicator to a respective exit pupil at or proximate the eye of the user by the holographic combiner.   
     
     
         11 . The method of  claim 1  wherein the first light signal includes an image comprising at least two pixels and redirecting respective ones of N instances of the first light signal towards the holographic combiner by the optical replicator includes redirecting N respective instances of a same image towards the holographic combiner by the optical replicator. 
     
     
         12 . The method of  claim 1  wherein redirecting respective ones of N instances of the first light signal towards the holographic combiner by the optical replicator includes redirecting N respective instances of a same pixel in a different instance of a same image towards the holographic combiner by the optical replicator.