Instrument for measuring the temporal characteristics of therapeutic ultrasound fields

An instrument is described that measures the ultrasonic frequency; pulse repetition rate; pulse duration; timer accuracy; peak-to-rms pressure amplitude ratio; and, peak-to-average intensity ratio for ultrasonic therapy devices designed for use in physical medicine. These temporal beam characteristics are included in a Food and Drug Administration performance standard for ultrasonic therapy products. They can be measured conveniently and efficiently when the instrument is used with an ultrasound transducer (hydrophone) to detect the radiated ultrasound beam. Instrument design is straightforward, employing standard analog and digital circuit components and modules. Frequency and time measurement errors are typically 1% or better. Pressure and intensity ratio errors are less than 2% and 4%, respectively.