A modified IFT-algorithm of synthesis of a kinoform is presented. In this method, two object-dependent filters
(the amplitude (A) filter and the phase (P) one) are formed in the object plane in the process of iteration,
rather than one phase filter, as usual. Both these filters participate in the formation of the phase structure of a
kinoform. The use of two degrees of freedom (A, P) in the object plane instead of one degree (P) accelerates the
convergence of the IFT-algorithm and allows one to reach significantly less values of the amplitude variance in
a reconstructed image as compared with those within the available methods. The results of optical and model
experiments confirming the efficiency of the method are given. It is found that the method is most efficient for
binary objects. The method is generalized to the case of off-axis kinoforms. A simple method to introduce the
carrier frequency into the structure of an axial kinoform is proposed. An image reconstructed by an off-axis
kinoform is free from the noises with zero and close frequencies caused by the nonideality of both the phase
mode of operation of a SLM and the effects of quantization of the registered phase.
The method of pattern recognition based on replacement of object images incoming to the correlator input
by object-dependent synthesized phase objects calculated using the iterative Fourier-transform algorithm was
developed by us earlier. In this work, we performed experimental testing the above method by using an opticaldigital
4F-correlator. Synthesized phase objects were introduced into the correlator through the spatial light
modulator LC 2002. Holographic matched filters were recorded using self-developing photopolymers PPC-488.
For two test objects, we obtained unified (δ-like) correlation signals with the signal-to-noise ratio reaching 24
dB, while the diffraction efficiency of these filters was up to 30%.
A new approach towards solving the pattern recognition problems in hybrid optical-digital 4F correlators is suggested. The method is based on that during the realization of the recognition procedure in the optical-digital correlator instead of real amplitude or amplitude-phase objects incoming on its input there is proposed to use synthesized phase (SP) objects unambiguously related to it. SP-objects represent object-dependent phase distributions calculated with application of iterative Fourier-transform (IFT) algorithm. Replacement of real objects with SP-objects allows to unify the shape (form) of correlation signals and so to formalize the procedure of choice of recognition attributes for objects of arbitrary classes. The modified recognition procedure in optical-digital correlators is presented, the influence of noises and distortions in the structure of input object upon characteristics of cross-correlation signal of corresponding SP-objects is studied. Numerical simulation results are presented.