Cavitation threshold pressure of focused ultrasound observed with sonochemiluminescence

Abstract Spatial distribution of sonochemiluminescence (SCL) from an argon-saturated luminol solution was measured in a focused sound field at 1 MHz standing-wave configuration. The SCL confined to pre-focal region acoustic powers lower than 0.9 W, and not located the focus but few mm side threshold for inception. pressure amplitude inception 3.6 atm focus, which value obtained with background-oriented schlieren method. method is based on broadening multiple slits due optical deflection caused by ultrasound, width provides amplitude. A qualitative image also obtained.