| 摘要 |
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. |
