Patents by Inventor Petra Ludwig

Petra Ludwig 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).

  • Operation microscope with an interference filter, and interference filter
    Patent number: 6028707
    Abstract: An operation microscope includes an illuminating device and an interference filter in the illuminating beam of the illuminating device. The interference filter is suitable for incorporation into the operation microscope. In order to prevent the yellow tinge that is present in long-known UV interference filters, the interference layer applied directly to the carrier substrate is a layer between 8 and 12 nm thick of yttrium fluoride, thorium fluoride, lanthanum fluoride or cerium fluoride.
    Type: Grant
    Filed: August 14, 1998
    Date of Patent: February 22, 2000
    Assignee: Carl-Zeiss-Stiftung trading as Carl Zeiss
    Inventors: Bernhard Ganswein, Andrea Mahler, Gerhard Moller, Petra Ludwig