Aris Tanone

Phase modulation depth for a real-time kinoform using a liquid crystal television

Interest in the liquid crystal television (LCTV) kinoform has been reported recently by several investigators. The technique requires a modulation depth of about 2π, which most of the commercially available LCTVs cannot attain. We discuss an experimental study of generating an LCTV kinoform in which the the modulation depth is limited by π. The major drawbacks of the ir phase variation are that, compared with 2π variation, it reduces the diffraction efficiency as well as the space bandwidth product to a degree of about one-fourth. Verification of these findings is reported.

Effects of thresholding in joint-transform correlation

The joint-transform power spectrum of two identical objects can be represented as a one-dimensional sinusoidal grating modulated by a Fourier transform, and the correlation peaks can be regarded as the first-order diffraction of the grating. The peak intensity and the width are then determined by the aperture and the modulation of the grating. Based on this analysis, it is shown that dc blocking, hard clipping, or binarization of the power spectrum results in higher correlation peak intensity and a narrower peak width. Direct-current blocking is also found to be preferable if the input pattern to the correlator is corrupted by noise.

Data association multiple target tracking using a phase-mostly liquid crystal television

This paper presents a technique of using data association target tracking in a motion sequence via an adaptive joint transform correlator. The massive data in the field of view can be reduced to a few correlation peaks. The average velocity of a target during the tracking cycle is then determined from the location of the correlation peak. We have used a data association algorithm for the analysis of these correlation signals, with which multiple targets can be tracked. A phase-mostly LCTV is used in the hybrid joint transform correlation system, and simultaneous tracking of three targets is demonstrated.

Closed-loop binary phase correction of an LCTV using a point diffraction interferometer

A point diffraction interferometer was used to examine the phase nonuniformity of a liquid-crystal television (LCTV). The resulting interference pattern was then binarized and written back onto the LCTV for phase compensation. A binary phase joint transform correlation experiment was performed using the binary phase corrected LCTV to demonstrate the applicability of this technique.<<ETX>>

Pendulum iterative algorithm for phase retrieval from modulus data

We present a pendulum iterative algorithm (PIA) to solve the phase retrieval problem. Computer simulations show that, in general, PIA converges faster than previous iterative algorithms in which the moduli of the object and the Fourier domain are provided. The performance of the PIA is compared with that of the error-reduction algorithm (ERA), the modified error-reduction algorithm (MERA), the input-output algorithm (IOA), and the hybrid IOA/ERA algorithm. We show that the PIA generally performs better for a binary modulus. In the case of a multilevel modulus, the PIA performs comparable to the hybrid IOA/ERA, while better than the others.

Holographic optical disk correlator

Abstract A novel optical joint transform correlator architecture using a holographic optical disk is described. The main advantages of the proposed system are high speed random accessibility and high strorage capacity. A proof-of-concept demonstration is given.

Electronic pseudocolor encoder for optical testing

An electronic pseudocolor encoder based on the principle of optical method is described. The system can perform pseudocolor encoding in real-time. A compact hand-held system consisting of monochrome CCD camera, electronics, and a liquid crystal display in a housing is presented. Example for optical testing is given.

Applications of liquid crystal spatial light modulators to optical information processing systems

This paper describes basic concepts of liquid crystal spatial light modulators, basic considerations for applying them in optical information processing system, some applications, and their future directions.

Multitarget tracking using a hybrid joint transform correlator

A technique using data association target tracking in a motion sequence via an adaptive joint transform correlator is presented. The massive data in the field of view can be reduced to a few correlation peaks. The average velocity of a target during the tracking cycle is then determined from the location of the correlation peak. A data-association algorithm is used for the analysis of these correlation signals, for which multiple targets can be tracked. A phase-mostly liquid-crystal TV is used in the hybrid joint transform correlation system, and simultaneous tracking of three targets is demonstrated.

High-efficiency joint-transform correlator for symbolic substitution

Symbolic substitution was firet proposed by Haung as a mean of utilising the parallelism of optics to perform digital computing. Essentially, it is a combination of recognition and substitution phase. In addition, although synibolic substitution is not restricted to space invariant operations, it is indeed based on the space invariant connectivity of optics. Therefore, holographic associative memory techniques may be alternatively applied to implement a symbolic substitution logic system.