Broadband method for measuring the ultrasonic absorption spectrum of biological tissues.

An apparatus is described which in the frequency range from about 5 to 500 MHz allows the ultrasonic absorption coefficient of biological tissues to be measured with 1% accuracy. This apparatus is based on a pulse transmission method in which a computer-controlled mode of operation is combined with a RF substitution technique. Superheterodyne detection of the transmitted signal, multiple data recording and signal averaging result in a high sensitivity of the measuring method. The apparatus can be also used to analyze the ultrasonic pulse reflected by the sample.