DEVELOPMENT OF A REAL-TIME SIGNAL-PROCESS ING FOR LASER-DOPPLER VELOCIMETER USING LIQUID-CRYSTAL SPATIAL LIGHT-MODULATOR

A multi-channel spectral analysis method, for multiple LDV signals, us ing an optical Fourier transform system is described. A Liquid Crystal Spatial Light Modulator (LCSLM) is employed to input the LDV signals to the system. As the electronics of LCSLM is same as a video, the inp ut temporal LDV signal is converted automatically into a spatial trans mission distribution in one-dimension, along the scanning line. It is possible to feed the signal from different points of measurement into each scanning line, and as we employed an anamorphic lens system; whic h performs the Fourier transform along the scanning line and images LC SLM in the perpendicular direction; we can obtain the frequency distri bution of LDV signal from independent points simultaneously. The resul ts of velocity distribution measurement, using the LDV system for dete rmination of the central position of rotation of a rotating object, ag ree well with that of calculations.