We analyze in depth several engineering problems regarding the construction of a VanderLugt correlator. Two liquid crystal devices are used in the input and Fourier planes and the large distances involved are reduced with the help of telephoto systems. An original method to control both modulators with a single 8-bit frame grabber and a single videoprojector electronics is presented. Problems related to pixel-by-pixel addressing and the phase modulation in the panels are also discussed. All the solutions proposed in this paper have been implemented and experimental correlation results using the setup have been obtained.