LASER INTERFEROMETRIC DETECTION OF ULTRASONIC-WAVES PROPAGATING INSIDE A TRANSPARENT SOLID

Ultrasonic waves propagating inside a transparent solid have been inve stigated by using a combination of laser interferometry and photoelast ic effect. In comparison with the classical photoelastic technique, th e present heterodyne method is sensitive not only to the amplitude but also to the phase of acoustic strains. Pulsed strains of longitudinal , shear, and Rayleigh waves have been experimentally achieved. The pha se changes of ultrasonic pulses reflected at the different interfaces were investigated. In addition, the polarization states of shear waves have been observed using the heterodyne detection.