Abstract: An apparatus for observing a sound field of an ultrasonic wave, including a first unit which determines characteristic values of a medium at each point of a predetermined region by an ultrasonic wave having a sound field of an arbitrary form and a second unit which displays an output of the first unit as two-dimensional or three-dimensional distribution in the predetermined region, and allows control of the form of the sound field of the ultrasonic wave.

Abstract: This invention relates to a system for measuring the non-linear parameter B/A of an ultrasonic medium such as a living tissue, namely the value which indicates a rate of change of the sound velocity with change of pressure, utilizing reflected ultrasonic waves. In this invention, a measuring burst pulse, having a comparatively high frequency, and a pumping pulse, having a comparatively low frequency and a high sound pressure, for giving a change of pressure are transmitted in the same direction while they are superposed, the phase of the reflected waves from each region of the ultrasonic medium is detected as a function of time, and it is then differentiated. Thereby, the distribution of B/A along the transmitting direction of said pulses can be obtained.

Abstract: 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.