Patents by Inventor Douglas N. DeFoe

Douglas N. DeFoe has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Optical collimating device employing cholesteric liquid crystal and a non-transmissive reflector
    Patent number: 5408346
    Abstract: An optical collimating device employs an optical (concave) mirror and cholesteric liquid crystal element to collimate and project image light into the line-of-sight of an observer in efficient manner. Image light is generated with light components within a predetermined bandwidth and with a predetermined rotary sense. The image light is directed so that it is reflected by the concave mirror, expanding (collimating) the image light, projecting in onto a cholesteric liquid crystal element that reflects those components of the image light within the bandwidth B and having the proper rotary sense of circular polarization. The cholesteric liquid crystal element substantially reflects the returned image to the observer.
    Type: Grant
    Filed: October 20, 1993
    Date of Patent: April 18, 1995
    Assignee: Kaiser Electro-Optics, Inc.
    Inventors: Richard G. Trissel, Douglas N. DeFoe