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Proceedings Paper

Measurement Of Fine Particulate In Pollution Control
Author(s): B. J. Matthews
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Paper Abstract

The technique of pulsed ruby laser holo-graphy has been adapted to record microscopic particles at large distances. The developed hologram reconstructs three-dimensional dark field records of scattered light images frozen during the ~50 x 10-9 second ruby laser pulse. Reconstructions may be analyzed to determine particle density. This is accomplished by measuring variations in absolute intensity of the reconstructed images and relating particle density to image intensity. The ability to determine particle density from absolute light intensity information contained in the holographic image was made possible with an improvement: the holocamera utilized two reference beams instead of one, each at a different angle relative to the scene beam. The second reference beam permits one to make absolute intensity measurements and thus direct comparisons between successive holograms. Separate tests have, in addition, indicated the extreme sensitivity of the three-beam holographic technique. Scene beam signals 10-° less intense than the second reference beam have been recorded, reconstructed and measured.

Paper Details

Date Published: 14 October 1971
PDF: 14 pages
Proc. SPIE 0025, Developments in Holography II, (14 October 1971); doi: 10.1117/12.953506
Show Author Affiliations
B. J. Matthews, TRW Systems Group (United States)

Published in SPIE Proceedings Vol. 0025:
Developments in Holography II
Brian J. Thompson; John B. DeVelis, Editor(s)

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