Enhanced techniques for ultrasonic power output measurement by modulated radiation pressure

Levels of time-averaged spatially-integrated output power radiated into reflectionless water loads are measured at NIST for sources up to 50 mm in diameter operating in the frequency range 0.5 MHz-30 MHz at output levels between 1 mW and 35 W. Used predominantly by diagnostic and therapeutic equipment manufacturers and others in the medical ultrasonics community, this calibration service has evolved significantly during the 16 years it has been offered. Improvements in purpose-built electronics have nearly halved overall uncertainties, to ±4% (2σ) for a 50 mm diameter source operating at 10 MHz, while extending the capabilities of the technique to include measuring the output of ultrasonic systems with arbitrary pulse waveforms