| 摘要 |
PURPOSE:To perform a measurement of a pressure, by a method wherein a surface of a piezo-electric object, which an ultrasonic wave propagates, is irradiated with light by the use of a fiber for projection, and a change in the frequency of the ultrasonic waves is detected from a reference light and a diffracted light of a reflecting light obtained at a fiber for reception. CONSTITUTION:Lower parts at both ends of a piezo-electric object 2, formed in a flat, are supported by supporters 2a, and a pressure P is exerted on the under surface. In an ultrasonic wave generator 3, electrodes 3a for producing ultrasonic wave, formed in the shape of a comb, are located at the left of the object 2, and an oscillator 3b is connected to the electrode 3a. Further, sound absorbing agents 3c are formed at the ends of the object 2, and the frequency of ultrasonic waves varies with a change in the pressure P. A fiber 4 for projection irradiates with light 1 at an angle thetai to the vertical axis of the object 2. In a fiber 5 for collection, a reference light L2, whose reflecting angle is unchangeable against a change in the frequency of the ultrasonic waves, and a diffracted light L3, whose diffraction angle varies, are obtained. A change in a diffraction angle thetad is measured from the reference light L2 and the diffracted light L3 to measure the pressure P. This permits measuring of only the pressure P through correction of vibration and temperature change. |
