超音波による回折スペクトルの測定方法と音速および吸収測定への応用
1969 年 38 巻 12 号 p. 1126-1132
詳細
1969 年 38 巻 12 号 p. 1126-1132
A technique for measuring ultrasonic light diffraction spectra is proposed. Frequency of the light diffracted by ultrasonic waves is shifted in the first spectral order by that of ultrasonic waves. By superposing a reference coherent light on the diffracted light, the resultant light having the same beat frequency as the frequency of the ultrasonic waves can be obtained. Photoelectric currents gained by scanning the focal plane are recorded through the amplifier tuned to the frequency of ultrasonic waves. The ultrasonic velocity and absorption in media are obtained by analyzing the spectra. A technique for measuring thevelocity of ultrasonic waves in media by utilizing the information included in the phase term of the heterodyne signal is also described. The optical arrangement has been so constructed as to eliminate several sources of errors, such as thedrift of output signals due to the absorption of the ultrasonic energy in- media, and the fluctuation of the output power of the gas laser used as the coherent light source. Some results for water, glycerol and polyethylene glycol are shownat the frequency of 2MHz. The accuracy of 0.5% is obtained for the velocity in water.
