Pulsed acoustic waves in water generated by ultrasonic transducers with power levels in the medical diagnostic range are characterized by analyzing the optical diffraction patterns of short laser pulses due to the pressure waves to be analyzed. The diffracted laser light is filtered in the Fourier plane of an optical system and projected onto a charge-coupled-device camera to be grabbed and further processed. Using this technique, it is possible to measure and characterize the ultrasound field in minutes time, which would otherwise last hours or days using the standard method of measuring the intensity on a fine three-dimensional grid with a hydrophone. In addition, the phase information of the ultrasonic wave is acquired easily.
['Erwin K. Reichel', 'Bernhard G. Zagar']
Phase contrast method for measuring ultrasonic fields