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Proceedings Paper

Optical Scanning System For Laser Velocimeter
Author(s): David B. Rhodes
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Paper Abstract

An optical system was developed to provide fast incremental scanning of a backscattered laser velocimeter focus point over a 36-cm distance. The system is used to measure flow velocities at 16 positions along its optical axis and to scan these 16 positions up to 30 times a second. Dwell time at each location is approximately 2 milliseconds. Sample volumes typically are 0.2 mm in diameter by 1.4 cm in length. The optical scanning system consists of a wheel containing plane parallel quartz windows of various thicknesses. The laser velocimeter beams are imaged to a primary focus within the dead airspace of an optical cell. -The beams emerging from the cell pass through the windows of the scanning wheel. The refraction of the beams passing through the windows causes an apparent shift of the focus within the optical cell and hence in the test zone. Light scattered from the secondary focus within the test zone is concurrently collected and reimaged through the same optical path which originally projected the primary focus. The reimaged backscattered light containing the velocity information is then collected and focused onto a photomultiplier detector system to complete the scanned laser velocimeter optical system.

Paper Details

Date Published: 10 January 1977
PDF: 7 pages
Proc. SPIE 0084, Laser Scanning Components and Techniques: Design Considerations/Trends, (10 January 1977); doi: 10.1117/12.954922
Show Author Affiliations
David B. Rhodes, Langley Research Center (United States)

Published in SPIE Proceedings Vol. 0084:
Laser Scanning Components and Techniques: Design Considerations/Trends
Leo Beiser; Gerald F. Marshall, Editor(s)

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