Visualization of high intensity focused ultrasound fields using image subtraction Schlieren technique and evaluation of focus depth

Abstract

A high intensity focused ultrasound (HIFU) field of a transducer for ultrasound therapy was visualized using an image subtraction Schlieren technique. The transducer of 110 mm in diameter and 100 mm in focal length was driven by a burst pulse of 1.58 MHz in center frequency and of 10 W in input electric power. Figure 1 shows beam profiles on the acoustic axis. A FWHM of the beam was 5.8 mm in a visualized field and was 7.3 mm in a field determined by hydrophone measurement.