The Directivity of a Laser-induced Thermoacoustic Array

date September 26, 1984
comments no comments.

Wednesday, September 26, 1984 12:00 p.m.

Yves H. Berthelot
Applied Research Laboratories
The University of Texas at Austin

A thermoacoustic array can be generated by modulating the intensity of a laser beam illuminating a liquid. The nearfield directivity pattern of a thermoacoustic array is found by taking the Fourier transform of the impulse response of the optoacoustic system. A simple expression in integral form has been derived for the directivity of a thermoacoustic array on a pressure release boundary such as an air/water interface. The integral is easily evaluated numerically and it clearly shows the presence of side lobes in the nearfield directivity. In the limiting case of farfield radiation the directivity computed numerically reduces to the farfield direc­tivity derived analytically. Experimental results will also be discussed.