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Title: Beam misalignments and fluid velocities in laser-induced thermal acoustics

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. {copyright} 1999 Optical Society of America

Authors:
;  [1];  [2]
  1. Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, California 91125 (United States)
  2. Sandia National Laboratories, Livermore, California 94551 (United States)
Publication Date:
OSTI Identifier:
690674
Resource Type:
Journal Article
Journal Name:
Applied Optics
Additional Journal Information:
Journal Volume: 38; Journal Issue: 27; Other Information: PBD: Sep 1999
Country of Publication:
United States
Language:
English
Subject:
44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; LIGHT SCATTERING; PHOTOACOUSTIC EFFECT; VELOCIMETERS; SOUND WAVES; FLUID FLOW; LEAST SQUARE FIT; LASER RADIATION; FREQUENCY MIXING

Citation Formats

Schlamp, S., Hornung, H.G., and Cummings, E.B. Beam misalignments and fluid velocities in laser-induced thermal acoustics. United States: N. p., 1999. Web. doi:10.1364/AO.38.005724.
Schlamp, S., Hornung, H.G., & Cummings, E.B. Beam misalignments and fluid velocities in laser-induced thermal acoustics. United States. doi:10.1364/AO.38.005724.
Schlamp, S., Hornung, H.G., and Cummings, E.B. Wed . "Beam misalignments and fluid velocities in laser-induced thermal acoustics". United States. doi:10.1364/AO.38.005724.
@article{osti_690674,
title = {Beam misalignments and fluid velocities in laser-induced thermal acoustics},
author = {Schlamp, S. and Hornung, H.G. and Cummings, E.B.},
abstractNote = {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. {copyright} 1999 Optical Society of America},
doi = {10.1364/AO.38.005724},
journal = {Applied Optics},
number = 27,
volume = 38,
place = {United States},
year = {1999},
month = {9}
}