Cummings, E. B. and Leyva, I. A. and Hornung, H. G. (1995) Laser-induced thermal acoustics (LITA) signals from finite beams. Applied Optics, 34 (15). pp. 3290-3302. ISSN 0003-6935. http://resolver.caltech.edu/CaltechAUTHORS:CUMao95
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Laser-induced thermal acoustics (LITA) is a four-wave mixing technique that may be employed to measure sound speeds, transport properties, velocities, and susceptibilities of fluids. It is particularly effective in high-pressure gases (>1 bar). An analytical expression for LITA signals is derived by the use of linearized equations of hydrodynamics and light scattering. This analysis, which includes full finite-beam-size effects and the optoacoustic effects of thermalization and electrostriction, predicts the amplitude and the time history of narrow-band time-resolved LITA and broadband spectrally resolved (multiplex) LITA signals. The time behavior of the detected LITA signal depends significantly on the detection solid angle, with implications for the measurement of diffusivities by the use of LITA and the proper physical picture of LITA scattering. This and other elements of the physics of LITA that emerge from the analysis are discussed. Theoretical signals are compared with experimental LITA data.
|Additional Information:||© 1995 Optical Society of America Received 19 August 1994; revised manuscript received 5 December 1994. The authors gratefully acknowledge the support of the University Research Initiative in aerothermochemistry sponsored by the U.S. Air Force Office of Scientific Research. E. Cummings is also indebted to the U.S. Office of Naval Research for its support of his graduate education through its fellowship program.|
|Subject Keywords:||LITA, finite-beam-size effects, thermal grating, electrostrictive grating, LITA velocimetry, multiplex LITA, data fits, dynamic light scattering|
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|Deposited On:||26 Oct 2006|
|Last Modified:||26 Dec 2012 08:41|
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