Patents by Inventor Darrell M. Postlethwaite

Darrell M. Postlethwaite 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).

  • Open area ratiometer
    Patent number: 4421409
    Abstract: An optical apparatus and method for measuring the percent of open area of a perforated sheet. The apparatus and method based on Fourier optics uses a light detector which measures only a small central portion of the light in a Fraunhofer diffraction pattern of the perforated sheet. The ratiometer offers both accurancy and speed in the measuring of the percent of open area while avoiding diffraction problems which are characteristic with arrays of small holes in the perforated sheet. Also, the invention can be used with both opaque and translucent materials.
    Type: Grant
    Filed: October 14, 1980
    Date of Patent: December 20, 1983
    Assignee: The Boeing Company
    Inventors: Fred M. Dickey, Darrell M. Postlethwaite