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Beam Misalignments and Fluid Velocities in Laser-Induced Thermal Acoustics

Schlamp, Stefan and Cummings, Eric B. and Hornung, Hans G. (1999) Beam Misalignments and Fluid Velocities in Laser-Induced Thermal Acoustics. Applied Optics, 38 (27). pp. 5724-5733. ISSN 0003-6935. http://resolver.caltech.edu/CaltechAUTHORS:SCHLao99

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Abstract

Beam misalignments and bulk fluid velocities can influence the time history and intensity of laser-induced thermal acoustics (LITA) signals. A closed-form analytic expression for LITA signals incorporating these effects is derived, allowing the magnitude of beam misalignment and velocity to be inferred from the signal shape. It is demonstrated how instantaneous, nonintrusive, and remote measurement of sound speed and velocity (Mach number) can be inferred simultaneously from homodyne-detected LITA signals. The effects of different forms of beam misalignment are explored experimentally and compared with theory, with good agreement, allowing the amount of misalignment to be measured from the LITA signal. This capability could be used to correct experimental misalignments and account for the effects of misalignment in other LITA measurements. It is shown that small beam misalignments have no influence on the accuracy or repeatability of sound speed measurements with LITA.


Item Type:Article
Additional Information:© Copyright 1999 Optical Society of America. Received 1 April 1999; revised manuscript received 21 June 1999. The authors acknowledge Thomas H. Sobota of Advanced Projects Research, Incorporated, for providing the motivation for understanding and characterizing the effects of beam misalignments and fluid velocity on the LITA signal. This research was supported by Advanced Projects Research, Incorporated, and the U.S. Air Force Research Laboratory at Edwards Air Force Base.
Subject Keywords:Four-wave mixing; Diffraction gratings; Metrology
Record Number:CaltechAUTHORS:SCHLao99
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:SCHLao99
Alternative URL:http://www.opticsinfobase.org/abstract.cfm?URI=ao-38-27-5724
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7689
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:22 Mar 2007
Last Modified:29 Aug 2014 14:36

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