Variable-depth stereoscopic display

Abstract

This document describes various techniques for implementing a variable-depth stereoscopic display. A first distance at which a viewer is disposed relative to a stereoscopic display is received. Once received, a second distance by which to change a front focal distance of a lens structure of the stereoscopic display is determined based on the first distance. The front focal distance of the lens structure is then caused to change by the second distance effective to display a stereoscopic image at the first distance.

1 . A method comprising:
 receiving a first distance at which a viewer is disposed relative to a stereoscopic display;   determining, based on the first distance, a second distance by which to change a front focal distance of a lens structure of the stereoscopic display; and   causing the focal distance of the lens structure to change by the second distance effective to display a stereoscopic image at the first distance.   
     
     
         2 . The method as recited in  claim 1 , wherein the stereoscopic display includes a liquid crystal lens configured to re-focus light emitted by the lens structure effective to change the front focal distance of the lens structure by the second distance. 
     
     
         3 . The method as recited in  claim 1  further comprising determining, based on the first distance, which of a first or a second light source of the stereoscopic display to use and wherein the causing causes the determined light source to inject light into the lens structure of the stereoscopic display. 
     
     
         4 . The method as recited in  claim 3 , wherein the lens structure an optical wedge configured to receive light from the determined light source and to emit light to display the stereoscopic image at the first distance. 
     
     
         5 . The method as recited in  claim 3 , wherein the first light source is operably coupled with a light guide, the light guide configured such that a back focal length associated with the first light source is different than a back focal length associated with the second light source. 
     
     
         6 . The method as recited in  claim 5 , wherein the respective back focal lengths associated with the first or the second light sources are effective to cause a front focal distance associated with the lens structure to be different depending on which of the first or the second light sources is caused to inject the light into the lens structure. 
     
     
         7 . The method as recited in  claim 3 , wherein the first or the second light source includes an array of light emitting diodes (LEDs) that are individually selectable to inject the light into the lens structure. 
     
     
         8 . An optical system comprising:
 two or more light sources individually selectable to emit light, each of the two or more light sources associated with a respective light guide having an optical path length that is different from an optical path length of a light guide associated with another of the two or more light sources;   a lens structure configured to receive light from one of the light guides associated with one of the two or more light sources and emit light useful to display stereoscopic imagery to a viewer;   a controller configured to:
 determine whether the viewer is within a front focal plane of the stereoscopic display; and 
 if the viewer is not in the front focal plane of the stereoscopic display, select another of the two or more light sources to change the front focal plane of the stereoscopic display. 
   
     
     
         9 . The optical system as recited in  claim 8 , wherein the lens structure is an optical wedge. 
     
     
         10 . The optical system as recited in  claim 8 , wherein the light guide associated with the other of the two or more light sources is configured to not occlude light emitted by the light source. 
     
     
         11 . The optical system as recited in  claim 8 , wherein the controller is further configured to receive viewer positional data from a sensor based on which the controller is configured to determine whether the viewer is within the front focal plane of the stereoscopic display. 
     
     
         12 . The optical system as recited in  claim 8 , wherein the controller is further configured to detect movement of the viewer in response to which the controller is configured to determine whether the viewer is within the front focal plane of the stereoscopic display. 
     
     
         13 . The optical system as recited in  claim 8 , wherein the optical system is configured as a non-projective flat panel display. 
     
     
         14 . The optical system as recited in  claim 8 , further comprising a spatial light modulator configured to modulate the light with parallax information associated with the stereoscopic imagery. 
     
     
         15 . A system comprising:
 a first light source and a second light source individually selectable to emit light;   a first light guide and a second light guide, the first and the second light guides configured to receive the light emitted from the first or the second light source respectively, the first light guide having an optical path length that is different from an optical path length of the second light guide;   a lens structure configured to receive the light from the first or the second light guides and emit light useful to display stereoscopic imagery to a viewer; and   a controller configured to select, based on an distance from the lens structure to the viewer, one of the first or the second light sources effective to set a front focal distance of the lens structure such that the front focal distance corresponds to the distance to the viewer.   
     
     
         16 . The system as recited in  claim 15 , wherein the lens structure is an optical wedge. 
     
     
         17 . The system as recited in  claim 15 , further comprising a light re-director configured to diffuse the light emitted by the lens structure. 
     
     
         18 . The system as recited in  claim 15 , wherein selecting the first light source is effective to cause the lens structure to have a first front focal distance and selecting the second light source is effective to cause the lens structure to have a second front focal distance. 
     
     
         19 . The system as recited in  claim 15 , wherein the first and the second front focal distances of the lens structure sufficiently overlap to provide the stereoscopic imagery continuously over the first and second front focal distances. 
     
     
         20 . The system as recited in  claim 15 , further comprising a spatial light modulator configured to modulate the light emitted by the lens structure.