| 摘要 |
PURPOSE:To impart a wide directional characteristic to the above hydrophone and to allow the exact measurement of the pressure of ultrasonic waves and impulsive wave by forming the part of a piezoelectric high-polymer film where the wave receiving electrodes are formed to a curved surface shape. CONSTITUTION:The piezoelectric high-polymer film 1 is a circular polyvinylidene fluoride film and the peripheral part is fixed by a supporting ring 2 made of a metal or resin. The film 1 is formed as the curved surface part curved in such a manner that the ultrasonic incident surface side in the central part constitutes a convex face and the opposite side a concave face. The wave receiving electrodes 3 are formed on both surfaces of such curved surface part so as to face each other. The value suitable for the required directional characteristic and sensitivity characteristic is selected for the radius of curvature of the electrodes 3. A piezoelectric effect is generated in the wave receiving region where the electrodes 3 of the film 1 is formed when the ultrasonic pulses are made incident on this hydrophone. The voltage pulses corresponding to the pressure of the incident ultrasonic pulses is then outputted via the electrodes 3 and the pulse waveforms thereof are observed on an oscilloscope. The pressure and pressure distribution of the incident ultrasonic pulses on the wave receiving region are determined from these pulse waveforms. |
