FOURIER TRANSFORMATION WITH A PLANAR HOLOGRAPHIC DOUBLET

The use of a single off-axis holographic lens for Fourier transformati on results in phase errors that degrade its performance. A configurati on of two identical off-axis holographic elements is proposed for perf orming Fourier transformation without phase errors. Such a configurati on can be readily folded to form a compact and cascadable element that can be conveniently incorporated into optical correlators. The gratin g functions of the holographic elements needed for performing the desi red transformation were used to record the planar configuration, which was then experimentally evaluated. The results reveal that phase erro rs were indeed eliminated, in close agreement with the calculations.