Modified liquid crystal television as a spatial light modulator

• US 4,715,683 A
• Filed: 11/10/1986
• Issued: 12/29/1987
• Est. Priority Date: 11/10/1986
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Gregory, Don A., Guenther, Bob D.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Gallivan, Richard F.
• Application Number:
  US06/928,492
• Time in Patent Office: 414 Days
• Field of Search: 350/331 R, 350/347 E, 350/345, 350/3.66, 350/3.67, 350/3.77, 350/337, 350/3.74
• US Class Current: 386/335
• CPC Class Codes: G03H 1/04 Processes or apparatus for producing holograms G03H1/26 takes precedence
• CPC Class Codes: G03H 2001/0066 for wavefront matching wherein the hologram is arranged to convert a predetermined wavefront into a comprehensive wave, e.g. associative memory recognition using holographic masks G06V10/88
• CPC Class Codes: G03H 2210/22 2D SLM object wherein the object beam is formed of the light modulated by the SLM SLM per se G03H2001/0224
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means

Abstract

The spatial light modulator utilizes a modified liquid crystal television for modulating a laser beam so as to produce a transformed hologram image on a film plate which is identical with the video information being fed into the liquid crystal TV. Once a image film has been produced the film is developed and placed back in the system so that the system will now act as a comparator and tracking device. With the reference beam blocked and a new video input fed into the liquid crystal TV the system now will have an output only when the scene on the TV is identical to the scene recorded on the film. Indicator means give a signal output from this comparison that is identical.

Claims

1. A system comprising a laser producing a laser beam, first means for splitting said laser beam into first and second parts, a liquid crystal television having a screen, a lens, input means connected to said television so as to cause a scene to be depicted on said screen, said screen positioned such that the first part of said laser beam will pass through said screen and be modulated by the scene thereon, and be transformed by said lens, film means being positioned so as to receive said first part of said laser beam after it passes through said screen, and said second part of said laser beam being directed towards said film means by a path which does not pass through said TV screen so as to act as a reference beam, whereby said film means will produce a holograph of said scene on said TV screen.

2. A system as set forth in claim 1 further comprising a first lens system having a pinhole construction so as to filter out higher orders of diffraction components due to electrode grid structure of the liquid crystal television screen, and said lens system being interposed between said screen and said film so as to perform its filtering functions.

3. A system as set forth in claim 2 wherein said film means is replaced with a developed hologram, blocking means located in the second part of said laser beams so as to selectively pass or block said second part of said laser beam, activating said blocking means to block said second part of said laser beam, said input to said TV being supplied so as to be compared with the information on said film means, and detecting means located relative to said film means for detecting when said input to said TV is the same as the information in said film means.

4. A system as set forth in claim 3 wherein better quality first and second polarizer are provided on either side of said screen so as to improve the image.