Mapping of an acoustic field by analysis of bubbles trajectory

It has been noted that in a high intensity field a bubble is pushed away in the ultrasonic propagation direction. The main action of an intense sound field on bubbles are usually identified as radiation pressure and, due to this force, the bubble-velocity in acoustic propagation direction is proportional to the square of the pressure amplitude. Then, when a bubble rises up through an acoustic field, its movement provides pinpoint information about this field. Calibrated bubbles with a constant and reproducible size are produced one at a time from a capillary tip. As a first step the experiment is shot with a video. As a second step, images are digitized and processed. Using bubbles of a hundred microns as a sensor does not disturb the investigated field. In this paper, the experimental setup and the mapping of a 2 MHz transducer field at pressure amplitudes of about 10 ⁴ Pa are presented