ACOUSTIC CHARACTERISTIC MEASURING APPARATUS

摘要

PURPOSE:To measure acoustic characteristic of material efficiently by having light beam travelling almost at the right angle to the advancing direction of ultrasonic waves with a sample to be measured set almost vertical to the advancing of the ultrasonic wave on an ultrasonic propagation medium. CONSTITUTION:When an accoustic sample 304 is inserted between a probe 101 and light beam 302 parallel to the light beam 302, as a sound transmits the sample 304, the pressure thereof reduces due to effect of attenuation and reflection of the sample 304. In this case, the reduction rate of the sound pressure is measured as changes in the intensity of the diffracted light of the light beam 302. Then, the frequency (f) of a drive voltage to be applied to an ultrasonic probe is changed and the transmittance the light is measured at respective frequencies (f). This gives the attenuation of the sample and the velocity of sound.