| 摘要 |
PURPOSE:To measure a higher harmonic component due to non-linear propagation in a state separated from other component according to a pulse echo method by respectively constituting a transmitter and a receiver specifically. CONSTITUTION:An annular array type transmitter-receiver is divided into ultrasonic vibrator element groups 1, 2 on a plane containing a center axis. The corresponding vibrator elements of the first and second groups are made possible to drive by fundamental frequencies mutually reverse in their phases. The double frequency echo reflected from the point reflector in the vicinity of a transmitting focus is received by ultrasonic vibrators 1, 2 and a transmitting-receiving circuit 13 and a delay time is added by a receiving focus circuit 14 and converted to echo intensity by a detection circuit 15 and the echo intensity at the time of double frequency same phase transmission is recorded on a memory circuit 16-2. The echo intensity at the time of fundamental frequency reverse phase transmission is once recorded on a memory circuit 16-1 to be inputted to a division circuit 17 and divided by the echo intensity from the corresponding position recorded on the memory circuit 16-2 to be outputted as the measured value corresponding to the non-linear coefficient in the vicinity of the position and a display circuit 18 displays an ultrasonic non-linear coefficient distribution image on the basis of the measured value. |
