This paper addresses itself to the problem of thermoacoustic generation by an obliquely incident laser beam in a body of water. Far-field directivity pattern of thermoacoustic source (TS) has been studied analytically and numerically. Our study suggests the possibility of getting highly directional sound beams in a simple configuration.

The paper presents an analysis of ultrasonic wave generation in water by intensity modulated elliptical Gaussian laser beams. It is found that generated acoustic radiation is highly directional both in polar and azimuthal directions. An increase in the assymmetry of the transverse intensity distribution from the Gaussian dependence enhances the source directivity considerably. An obvious conclusion is that elliptical Gaussian beams are better choice in applications where it is desired to communicate in an approximately prescribed small solid angle.