Patents by Inventor Kurt Kirchhoff

Kurt Kirchhoff 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).

  • Three-element projection lenses
    Patent number: 3936155
    Abstract: A triplet-type three element lens comprises three lens elements made of substantially the same optical glass. The glass may be crown glass having an Abbe number greater than 50, a refractive index of less than 1.535 and a specific gravity of less than 2.7. The lens may be symmetrical comprising front and rear planoconvex lenses and a central biconcave lens.
    Type: Grant
    Filed: January 9, 1974
    Date of Patent: February 3, 1976
    Assignee: Heinrich Reichmann
    Inventor: Kurt Kirchhoff