Abstract

The optical fluid flow measurement technique of particle image velocimetry (PIV) relies on photographing, under pulsed illumination, small seeding particles carried along in the flow. After development of the film the local velocity in any area of the flow is given by the separation of particles in the image. One method of determining this separation is to pointwise interrogate the film with a laser beam and measure the spacing of the resultant fringes. This is generally performed by capturing the fringes with a video or CCD camera, digitizing them, and performing a Fourier transform. Automatic measurement systems for this task have been set up in several laboratories, and some researchers have also investigated the possibility of using photorefractives for processing the fringes. In this paper, we demonstrate using a ferroelectric liquid crystal, optically addressed spatial light modulator (OASLM) to perform the Fourier transform much faster than is possible with conventional methods.

© 1991 Optical Society of America