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Proceedings Paper

Optical filters to exclude non-Doppler-shifted light in fast velocimetry
Author(s): David R. Goosman; George R. Avara; James T. Wade; Anthony T. Rivera
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Paper Abstract

We frequently measure velocity-time histories of dynamic experiments. In some, the Doppler-shifted light is often weak compared to non-shifted light reflected from stationary surfaces and imperfections in components. With our Fabry-Perot (FP) based systems which handle multiple frequencies, data is lost where the fringes coincide; if we had used an intensity-measuring VISAR system, it would probably fail. We designed a facility for doing experiments under such conditions by selectively eliminating most of the non-shifted light. Our first filter excluded non-shifted light by a factor of 300 when manually tuned, and by 150 when run in an auto-tuning mode. It used a single 50 mm diameter FP as the filter with a spacing of 1.65 mm and reflectivities of 77%, and filters five channels prior to use in one of our 5-beam velocimeters. One use of the filter system was to embed optical fibers in long sections of explosives to make continuous detonation velocity-time histories. We have carried out many such tests with this filter, and two without. A special single-beam filter was constructed with a 40% efficiency for shifted light that rejected non-shifted light by 4 million times, with a bandpass of a few GHz.

Paper Details

Date Published: 1 August 2003
PDF: 8 pages
Proc. SPIE 4948, 25th International Congress on High-Speed Photography and Photonics, (1 August 2003); doi: 10.1117/12.516818
Show Author Affiliations
David R. Goosman, Lawrence Livermore National Lab. (United States)
George R. Avara, Lawrence Livermore National Lab. (United States)
James T. Wade, Lawrence Livermore National Lab. (United States)
Anthony T. Rivera, Lawrence Livermore National Lab. (United States)

Published in SPIE Proceedings Vol. 4948:
25th International Congress on High-Speed Photography and Photonics
Claude Cavailler; Graham P. Haddleton; Manfred Hugenschmidt, Editor(s)

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