Experimental Studies on Sonoluminescence and Ultrasonic Cavitation

Using a miniature spherical hydrophone made of barium titanate, the individual cavity collapse was detected as a sharp impulse (0.5 µs width) slightly after the pressure maximum of sound cycle. When may cavities collapsed simultaneously, sinusoidal sound-pressure waveform was turned into saw-tooth form. By comparing the flash of sonoluminescence with the instantaneous change of scattered light from cavitating bubbles in dark-fiield illumination, the sonoluminescence from water has been decided to occur during the final stages of the bubble collapse. The sonoluminescence from aqueous solutions of various sodium salts, organic solvents and luminol has also examined. The luminescence of luminescence of luminol has been applied to develop a new method for the visualization of ultrasonic fields.