Nonlinear filtering in object and Fourier space in a joint transform optical correlator: comparison and experimental realization

The use of different kinds of nonlinear filtering in a joint transform correlator are studied and compared. The study is divided into two parts, one corresponding to object space and the second to the Fourier domain of the joint power spectrum. In the first part, phase and inverse filters are computed; their inverse Fourier transforms are also computed, thereby becoming the reference in the object space. In the Fourier space, the binarization of the power spectrum is realized and compared with a new procedure for removing the spatial envelope. All cases are simulated and experimentally implemented by a compact joint transform correlator

Pattern detection using a modified composite filter with nonlinear joint transform correlator

A simple method for optical implementation of a composite filter in a joint transform correlator is presented. A composite filter in object space is a real function, but by adding an appropriate constant value, only positive values are obtained. As a drawback, the bias introduced decreases the relative height of the correlation peaks in the recognition process. Non-linear effects in a joint transform correlator are used to increase discrimination by using positive composite filters. Digital simulation and optical implementation of the process has been carried out, achieving the non-linearities by means of saturation effects on the intensity detection process

Noves metodologies docents per millorar l'aprenentatge en l'assignatura d'òptica del grau de Física

En el curs 2010/2011 es va impartir per primer cop la nova assignatura d'Òptica de grau. A diferència del que succeïa en l'antiga llicenciatura de Física, les pràctiques de laboratori estan incloses en l'assignatura de teoria i problemes i es fan simultàniament. Volem introduir una sèrie d'eines d'auto-aprenentatge i avaluació per tal que els alumnes puguin assolir una sèrie de coneixements prèviament a les sessions de laboratori, de forma que el grau d'aprofitament de les pràctiques sigui major

Optical correlation by use of partial phase-only modulation with VGA liquid-crystal displays

The development of liquid-crystal panels for use in commercial equipment has been aimed at improving the pixel resolution and the display efficiency. These improvements have led to a reduction in the thickness of such devices, among other outcomes, that involves a loss in phase modulation. We propose a modification of the classical phase-only filter to permit displays in VGA liquid-crystal panels with a constant amplitude modulation and less than a 2¿(PI) phase modulation. The method was tested experimentally in an optical setup