Measuring method and apparatus for non-linear parameter of acoustic medium and its application

摘要

A measuring method and apparatus for measuring a non-linear parameter of an acoustic medium or its distribution, and the application of the parameter to the measurement of internal temperature of a sample noninvasively. A continuous wave ultrasonic probing beam is radiated through the sample, and a pumping wave which is an ultrasonic pulse is superposed on the probing beam. A phase change in the probing beam caused by the pumping wave is detected. From this phase change the non-linear parameter (B/A) is obtained. The invention projects two methods. The first method provides the pumping wave in a direction intersecting the probing beam. The second method projects the pumping wave in a direction along the probing beam in counter direction. From the information concerning the variation of measured value of (B/A), the inner temperature of the sample is obtained. The invention makes it possible to measure the non-linear parameter or temperature which was impossible in the prior art.