A simple Schlieren system for visualizing a sound field of pulsed ultrasound

Abstract

A new Schlieren method for visualizing an acoustic field of pulsed ultrasound was proposed, and a system was developed to evaluate the validity of the proposed method by visualizing an acoustic field of a focused ultrasound field of diagnostic frequency range. A conventional Schlieren optical system is not used in the developed system. The system uses a short-pulsed laser, a CCD camera with a wide dynamic range, and a PC that processes images captured by the CCD camera. In the proposed method, extraction of light diffracted by ultrasound is carried out by subtraction of images captured with and without ultrasound exposure. The usefulness of the developed system was confirmed by an experiment in which acoustic fields of a 5-MHz focused transducer were visualized. Good agreement was found between the visualized and simulated ultrasound fields.