鏡面反射光を利用した固体表面速度および角度のレーザー・ドップラ計測

抄録

On the measurement of velocity of moving solid surface by using a laser Doppler velocimeter (LDV), diffuse and specular reflection can be observed in the back scattering region. Since the specular reflection (SR) is followed by the law of geometrical optics, direction of the reflected beam changes With the moving angle of solid surface. However, the utilization of SR has never been considered on the LDV measurement.
In this study, we proposed a new differential method of LDV, in which the SR beam was again reflected by means of a mirror (specular re-reflection, SRR) and arranged to enter into the sampling volume as an incident light. As consequence by crossing three laser beams (SR and two inherent incident beams) in the focal, point, three different interference were constructed in the sampling volume. When scatters pass through the sampling volume, scattered light emits and involves three different Doppler frequency shifts which give an information regarding the velocity of the solid surface and the moving angle.
In the present paper, theoretical investigation was carried out about the effect of SRR on the Doppler signals correlated with the moving angle of the solid surface. Fundamental experiment was also carried out by using a rotating disk and the results were compared with the theoretical aspects. Application of the Doppler effect caused by SRR was additionally discussed.