格子状空間フィルターを用いた微小域用差動型速度計

抄録

A method of measuring velocity using a grating spatial filter in a microscopic area is described. The images corresponding to particles moving in a probing region are formed on the grating placed in front of a photodetector. The particle velocity is determined from the frequency measurement of eletrical output signals obtained from the photodetector. In this paper, the filtering characteristics of the grating used is analyzed by means of the power spectral density function for the two cases of single and differential detection systems. The preliminary experiment of velocity measurements is performed by using a part of the circumference of a rotating random pattern. The theoretical and experimental results show that the differential detection system is useful for measurements of the velocity in a microscopic area where only a small number n of spatial filter lines exists.