Visualization of high frequency ultrasonic wavefronts by holographic interferometry

Ultrasonic fields in glycerol are visualized by holographic interferometry with a phase-modulated reference beam. Fine particles suspended in glycerol are illuminated with sheet-like light, and the light scattered from the illuminated plane is recorded in a hologram. The ultrasonic field on the plane is displayed in the reconstructed image, which provides equiphase positions of the wave, i.e., wavefronts. The experiments are done with an ultrasound of frequency 1 MHz. The wavefronts of the ultrasounds scattered or reflected by obstacles are visualized on some cross-sectional planes. The experiments demonstrate that the method can visualize the three-dimensional ultrasonic fields.