Patents by Inventor Johannes M. Wittkamper

Johannes M. Wittkamper 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).

  • Patent number: 4450553
    Abstract: The invention relates to a multilayer information disc, in particular a video disc, which is read by laser light. The disc comprises at least two radiation-reflecting optical structures each having a relief-like information track of regions situated alternately at a higher and a lower level which is read in reflection and on the basis of phase differences. Each of the optical structures is covered with a reflection layer at least one of which partially transmits the reading radiation so that upon reading the other optical structure or structures, the radiation passes through the structure provided with the partially transmitting reflection layer. The coefficients of reflection of the various reflective layers are preferably matched to each other in a manner such that upon reading the same amount of light returns from each optical structure. A suitable material for the partially reflective layer is a dielectric which has no light absorption.
    Type: Grant
    Filed: January 26, 1979
    Date of Patent: May 22, 1984
    Assignee: U.S. Philips Corporation
    Inventors: Peter L. Holster, Johannes M. Wittkamper