A CALORIMETER FOR ULTRASOUND TOTAL POWER MEASUREMENTS

A simple, rugged, absolute calorimeter is described, based on an inversion of Fitch's method for thermal conductivity determination. This calorimeter operates in the range of 0-10 W with linearity of 0.15% over this power range. The minimum detectable power change is 10 mW. The response time of the calorimeter depends on the configuration adopted to absorb the input power, and can lie in the range from 48 to 405 s, depending on the diameter of the calorimeter absorbing region. Results obtained from acoustic power measurements at 1 MHz are demonstrated. Its use is not confined to ultrasound power measurements