Abstract

Optical probe for visualizing ultrasonic traveling wave-front has long attracted considerable attention in the acoustics field. In recent years, we have established a series of methods to display the image of wave-front for ultrasonic traveling wave of an acousto-optic device. The methods are based on the correlation theory and by using cw laser beam. Special spatial filtering technique has been used. (It is different from the general spatial filtering technique for the steady phase object, for instance, Schlieren method, Zernike phase contrast method, dark ground field method, etc.) It is based on considering the temporal frequency spectrum in spatial frequency spectrum of ultrasonic traveling wavefront which is a moving phase object illuminated by multi-frequency light beam which is one of the diffracted beams of standing wave device driven synchronously with the traveling wave device through a frequency dividing circuit. By analyzing the temporal frequency spectrum in the spatial frequency spectrum of the traveling wavefront illuminated by one of the diffracted beams which has multi-frequency and different phase, we have taken a special spacial filtering technique to obtain a high contrast image of the ultrasonic traveling wavefront. The results of our experiments are well desired as the theory predicted by us. The technique is more convenient to be established and much cheaper than others.

© 1990 Optical Society of America