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22 May 1998Multiple-image control with an 8-bit frame grabber: use in a Vander Lugt correlator
The reduction of geometrical distances in optical correlators, in order to build miniaturized systems, has become a necessity for realistic applications [1]. In general, the scope of the studies carried out is only focused in some parts of the problem. Nowadays, liquid crystal devices (LCD), usually removed from commercial videoprojectors, are used to display images in optical setups. As a result of using pixelated panels, the viability study of building an optical correlator in a reduced space should not be only limited to a design of optical systems. It must include an analysis of the behaviour of the displaying devices. Another issue that has not been raised yet is the reduction of the material needed to control simultaneously two LCDs in a Vander Lugt correlator, which involves a duplication in the driving electronics. We analyze in depth several engineering problems regarding the construction of a Vander Lugt correlator with LCDs at the input and Fourier planes. In order to reduce the length of the setup we have designed two telephoto systems. An original method to control both devices with a single 8-bit frame grabber and a single videoprojector electronics is presented. We have solved the problems related to pixel-by-pixel control when displaying the data from the frame grabber on the LCDs. An accurate analysis of the phase modulation capability of the panels is also discussed. Experimental results obtained with this setup are presented.
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Ignasi Juan I. Labastida, Arturo Carnicer, Estela Martin-Badosa, Santiago Vallmitjana, Ignacio Prades Juvells, "Multiple-image control with an 8-bit frame grabber: use in a Vander Lugt correlator," Proc. SPIE 3490, Optics in Computing '98, (22 May 1998); https://doi.org/10.1117/12.308918