Holographic display

Abstract

A method of displaying a Computer Generated Holographic (CGH) image by a display, including setting pixel values of a Spatial Light Modulator (SLM) included in a Head Mounted Display (HMD), producing a interference based holographic image at a first location by projecting coherent light onto the SLM, and re-imaging the holographic image from the first location to form a holographic image in front of an eye of a viewer wearing the HMD. Related apparatus and methods are also described.

1 . A method of displaying a Computer Generated Holographic (CGH) image by a display, comprising:
 setting pixel values of a Spatial Light Modulator (SLM) comprised in a Head Mounted Display (HMD);   producing an interference based holographic image at a first location by projecting coherent light onto said SLM;   using an imaging optical component for imaging an image of said SLM to a second location;   using a direction-adjustable optical component at said first location for directing said image of said SLM to a pupil of a viewer wearing said HMD and directing said holographic image from said first location to form a holographic image in front of an eye of said viewer.   
     
     
         2 . (canceled). 
     
     
         3 . The method of  claim 1  and further comprising enabling the eye of the viewer to view a real world view in addition to the holographic image and blocking a portion of the real world view, the portion of the real world view being blocked overlapping, at least in part, at least a portion of the holographic image. 
     
     
         4 . The method of  claim 1  and further comprising re-imaging said holographic image from said first location to form a holographic virtual image and re imaging said image of said SLM at said pupil of said viewer. 
     
     
         5 - 7 . (canceled). 
     
     
         8 . The method of  claim 53  and further comprising:
 tracking a direction in which said HMD is pointing; 
 when a change in said direction said HMD is pointing is detected, adjusting said second direction-adjustable optical element so as to make said holographic image appear at a same location as prior to said change. 
 
     
     
         9 . The method of  claim 1  in which:
 said setting pixel values of said SLM comprises setting a first set of pixel values of said SLM for producing a first portion of said holographic image; 
 said producing said holographic image at a first location by projecting coherent light onto said SLM comprises projecting said first portion of said holographic image onto said first location; and 
 using said second direction-adjustable optical element for directing said first portion of said holographic image from said first location to form a first portion of said holographic image at a third location in front of said eye of said viewer; 
 and further comprising: 
 setting a second set of pixel values of said SLM for producing a second portion of said holographic image; 
 producing said second portion of said holographic image by projecting coherent light onto said SLM and projecting said second portion of said holographic image onto said first location; and 
 using said second direction-adjustable optical element for projecting said second portion of said holographic image from said first location to form a second portion of said holographic image at a fourth location in front of said eye of said viewer, said fourth location in front of said eye of said viewer being adjacent to said third location in front of said eye of said viewer, such that said second portion of said holographic image appears adjacent to said first portion of said holographic image. 
 
     
     
         10 - 11 . (canceled). 
     
     
         12 . The method of  claim 1  in which
 said directing said holographic image from said first location toward said eye of said viewer comprises adjusting a direction of said direction-adjustable optical element to direct said holographic image from said first location toward said eye of said viewer. 
 
     
     
         13 . The method of  claim 1  and further comprising:
 tracking a location of a pupil of said eye of said viewer; 
 when a change in location of said pupil is detected, adjusting a location of said directing said image of said SLM to keep said image of the SLM at a vicinity of said viewer's pupil responsive to said change in location of said pupil by using said first direction-adjustable optical element. 
 
     
     
         14 - 16 . (canceled). 
     
     
         17 . The method of  claim 1  in which said setting pixel values of said SLM further comprises distributing a calculating of said pixel values between a computer external to said HMD and a computing unit on-board said HMD and said computer external to said HMD calculates pixel values for a tile smaller than an entire area of said SLM, and said on-board computing unit calculates pixel values of said entire area of said SLM. 
     
     
         18 . (canceled). 
     
     
         19 . The method of  claim 1  in which said setting pixel values of said SLM comprised in said display and said producing a holographic image at a first location comprises setting pixel values and producing a holographic image comprising multiple focal planes relative to said viewer's point of view. 
     
     
         20 . A system for displaying an interference based holographic image by a display, the system comprising:
 a Spatial Light Modulator (SLM);   a source of coherent light for projecting onto said SLM for producing an interference based holographic image at a first location and an image of said SLM at a second location;   an imaging component for re-imaging said image of said SLM to a viewer's pupil and re-imaging said holographic image from said first location to form a holographic virtual image in front of an eye of said viewer, and;   a first optical component at said first location for directing an image of said SLM to a pupil of an eye of a viewer.   
     
     
         21 . The system of  claim 20  and further comprising the system enabling the eye of the viewer to view a real world view in addition to the holographic image. 
     
     
         22 - 23 . (canceled). 
     
     
         24 . The system of  claim 20  in which:
 said producing an interference based holographic image at a first location comprises producing a holographic real image; and 
 said directing said holographic image from said first location to form a holographic image in front of said eye of said viewer comprises re-imaging said holographic image and producing a holographic virtual image. 
 
     
     
         25 . (canceled). 
     
     
         26 . The system of  claim 20  and further comprising:
 a direction-tracker for tracking a direction said display is pointing; and 
 a direction-adjustable optical element at said second location for adjusting said projecting said holographic image from said first location to form a holographic image in front of said eye of said viewer to make said holographic image appear at a same location responsive to a change in direction detected by said direction-tracker, 
 in which said direction controller comprises a direction-adjustable optical component selected from a group consisting of: 
 a controllable tilting mirror; 
 a controllable tilting prism; 
 a controllable image redirection element. 
 
     
     
         27 . (canceled). 
     
     
         28 . The system of  claim 20  and further comprising:
 a location-tracker for tracking a change in location of said display; and 
 a location controller for setting values of said pixels of said SLM to make said holographic image appear at a same location as prior to said change in location of said display. 
 
     
     
         29 . The system of  claim 24  and further comprising a sensor arranged to read a location of an object inserted into a same space as said holographic virtual image displayed in front of said eye of said viewer. 
     
     
         30 . The system of  claim 20  and further comprising a transparent liquid crystal display between an apparent location of said holographic virtual image and said eye of said viewer, in which said liquid crystal display is configured to block light from a direction of said apparent location of said holographic virtual image to said eye of said viewer, thereby increasing a contrast between said holographic virtual image and a background of said holographic virtual image. 
     
     
         31 - 32 . (canceled). 
     
     
         33 . The system of  claim 20  in which:
 said producing a holographic image at a first location comprises producing said holographic image to comprise multiple focal planes; and 
 said directing said holographic image from said first location to form a holographic virtual image in front of said eye of said viewer wearing said display comprises directing said multiple focal planes, relative to said viewer's point of view, to apparent distances in a range from as close as an apparent 30 cm from said eye of said viewer to as far as apparent optical infinity. 
 
     
     
         34 - 47 . (canceled). 
     
     
         48 . The system of  claim 20  and further comprising a partially-reflecting mirror in front of an eye of a viewer. 
     
     
         49 . The system of  claim 20  and further comprising the system being mounted on an adjustable arm, the adjustable arm being arranged to enable movement of the system so as to place a partially-reflecting mirror in front of said viewer's face. 
     
     
         50 . The system of  claim 20  wherein said first optical component comprises a first direction-adjustable optical element and further comprising a second direction-adjustable optical element placed at said second location. 
     
     
         51 . The method of  claim 1  wherein:
 said imaging optical component images the holographic image to a third location, 
 further comprising an additional optical component for re-imaging said image of said SLM from said second location and for re-imaging said holographic image from said third location to form a virtual holographic image in front of said eye of said viewer; and 
 using said direction-adjustable optical component comprises using said direction-adjustable optical component at said third location for directing said image of said SLM to said pupil of said viewer and directing said holographic image from said third location to form said virtual holographic image in front of said eye of said viewer. 
 
     
     
         52 . A display for displaying an interference based holographic image by a display, the display comprising:
 a Spatial Light Modulator (SLM);   a source of coherent light for projecting onto said SLM for producing an interference based holographic image at a first location and an image of said SLM at a second location; and   an optical imaging element for re-imaging said image of the SLM from said second location to a viewer's pupil and for re-imaging the holographic image from said first location to form a holographic virtual image in front of an eye of the viewer,   wherein the system is mounted on an adjustable arm, the adjustable arm being arranged to be movable by hand so as to place the holographic virtual image in front of said viewer's face.   
     
     
         53 . The method of  claim 1  and further comprising placing a second direction-adjustable optical element at said second location.