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Applied Optics

Applied Optics


  • Vol. 38, Iss. 27 — Sep. 20, 1999
  • pp: 5724–5733

Beam misalignments and fluid velocities in laser-induced thermal acoustics

Stefan Schlamp, Eric B. Cummings, and Hans G. Hornung  »View Author Affiliations

Applied Optics, Vol. 38, Issue 27, pp. 5724-5733 (1999)

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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.

© 1999 Optical Society of America

OCIS Codes
(000.2170) General : Equipment and techniques
(050.2770) Diffraction and gratings : Gratings
(120.6780) Instrumentation, measurement, and metrology : Temperature
(120.7280) Instrumentation, measurement, and metrology : Vibration analysis
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing

Original Manuscript: April 1, 1999
Revised Manuscript: June 21, 1999
Published: September 20, 1999

Stefan Schlamp, Eric B. Cummings, and Hans G. Hornung, "Beam misalignments and fluid velocities in laser-induced thermal acoustics," Appl. Opt. 38, 5724-5733 (1999)

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