Focusing and beamsteering of laser generated ultrasound

The generation of acoustical waves in solids by pulsed laser irradiation has the advantage of being contactless and nondestructive in the case of the thermoelastic mode. Unfortunately, acoustical characteristics of such a source are limited. To modify these parameters, a phased array of thermooptical sources was made by moving the laser beam, and control of beam directivity was obtained. Achievement of such an array is accomplished with an acoustooptic deflector synchronized with a large pulse dye laser. The influence of the velocity and geometry of the moving source is studied, and comparison with a motionless source is made.<>