Among the various evaluation techniques suggested for analysis of PIV images is the evaluation of the scattered interference pattern (Young's fringes) by numerical Fourier transform. An alternative to the numerical calculation of the Fourier transform of the Young's fringes has been suggested, using a modified liquid crystal television as an optical correlator to allow the transform to be performed optically, thus speeding up the interrogation process.
Both transform techniques are affected by the quality of the input function, specifically the Young's fringes. This paper will compare the performance of optical and numerical fourier transform analysis of Young's fringes using speckle images.
The repeatability and an estimate of the accuracy of the particle displacement will be shown for each method.