| 摘要 |
PURPOSE:To obtain an ultrasonic picture with high S/N by a method wherein an electric signal having a modified frequency is impressed on a piezoelectric transducer so as to determine a frequency whose amplitude is maximum, and the frequency of a high-frequency pulse signal for forming an ultrasonic microscope picture is set according to the frequency thus determined. CONSTITUTION:A piezoelectric transducer 41 has an electrode 42 for transmission and reception and an electrode 43 for monitoring a frequency on the upper end surface of an acoustic lens 8. A signal generated by a high-frequency pulse generator 15 passes through a circulator 16 and is impressed on the electrode 42 and an earthing electrode, and an ultrasonic wave is transmitted onto the sample 11 side. The ultrasonic wave reflected by the sample 11 is transduced again into an electric signal by the transducer 41, and it passes through the circulator 16 and is introduced into a gate circuit 18 and displayed in a TV monitor 27. The signal of the electrode 43 is stored in a memory 50 through a detection circuit 48, and it is subjected to an arithmetic operation by an operation processing unit 53 after sweeping for one period. The generator 15 is controlled so that the amplitude of the transducer 41 by made maximum by an operation output. In this way, an ultrasonic picture with high S/N can be obtained. |
