Design of compact joint transform correlator

To improve the quality of images taken with spatial cameras, we measure sub-pixel shift between two adjacent images, using a joint transform correlator (JTC). First we describe the principles of measurements of the image shifts based on the JTC. Then, considering discrete pixel-like structures of a CCD and a spatial light modulator, we discuss relationships among the parameters of JTC components, issuing from the sampling theorem and the Fourier optics principles. Following from these points, we select the devices needed and design the Fourier lens to construct a compact JTC. Finally, we build the experimental platform and estimate the efficiency of measurements of the image shifts. The results show that sub-pixel image shifts can be measured very accurately, with the errors being less than 0.1 pixel under condition that the image shifts are within 1 pixel.