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Phase-shifting point diffraction interferometer

United States Patent

5,835,217
November 10, 1998
View the Complete Patent at the US Patent & Trademark Office
Lawrence Berkeley National Laboratory - Visit the Technology Transfer and Intellectual Property Management Department Website
Disclosed is a point diffraction interferometer for evaluating the quality of a test optic. In operation, the point diffraction interferometer includes a source of radiation, the test optic, a beam divider, a reference wave pinhole located at an image plane downstream from the test optic, and a detector for detecting an interference pattern produced between a reference wave emitted by the pinhole and a test wave emitted from the test optic. The beam divider produces separate reference and test beams which focus at different laterally separated positions on the image plane. The reference wave pinhole is placed at a region of high intensity (e.g., the focal point) for the reference beam. This allows reference wave to be produced at a relatively high intensity. Also, the beam divider may include elements for phase shifting one or both of the reference and test beams.
Medecki; Hector (Berkeley, CA)
The Regents of the University of California (Oakland, CA)
08/ 808,081
February 28, 1997
This invention was made, in part, with U.S. and government support and the contract number DE-AC03-76SF00098, awarded by the Department of Energy. The government has certain rights in this invention.