Physical Optics Corporation has developed an automatic polarization sensitive multispectral imaging system for real-time object-to-background contrast enhancement This system is built around an acousto-optic tunable filter and liquid crystal achromatic rotator oflight polarization.Compared with the previously developed multispectral systems, the perfonnance algorithm takes advantage of the additional information provided by light polarization. Spectral images taken in both orthogonal light polarizations are used for calculating the spectrally-matched filter, thus doubling the dimension of the feature space used for the best separation of the selected object over a cluttered background.The system described is capable of near real time (4 frames per second) object contrast enhancement and background suppression without intensive computer post-processing of multispectral data. It does not require a large volume of data storage and a wide-band communication link between the remote sensor and operations center. By providing real-time contrast enhancement this systems improves conditions for subsequent object recognition by a human operator or a computer algorithm.

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By utilizing the unique AOTF feature of varying its spectral transmission according to the spectrum of the driving RF signal, Physical Optics Corporation developed an automatic hyperspectral system for real-time target contrast enhancement and target tracking.The system performance algorithm includes automatic collection of initial spectral information in the scene of observation. Depending on the application scenario, either a data bank of target spectral signatures or the spectral signature of an object in the scene selected by an operator is used to calculate the parameters ofthe spectrally matched filter. This process enhances target contrast and suppresses background clutter. Therefore, the AOTF driving signal for the calculated spectrally matched filter is synthesized under computer control so an image with enhanced target contrast can be acquired immediately.Image acquisition through the spectrally matched filter can be continued until target movement or variation in illumination significantly changes the target or background spectral signatures.The system described eliminates intensive computer post-processing of hyperspectral data. It does not require a large volume of data storage or a wide band communication link between the remote sensor and the command center. By providing real-time target contrast enhancement, this system improves conditions for subsequent target recognition by a human operator or a computer algorithm.

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The goal of this work was to develop a fast optical correlator for automatic real-time target recognition. The tremendous importance of optical correlators for military and civilian applications was recognized recently and approved by a U.S. conference committee of senators and representatives.This publication presents the experimental results of detecting and identifying complex scattered signals by using an innovative, hybrid electro-optical correlator. Our technique is based on achieving optical correlation by utilizing state-of-theart devices: time delay integration (ThI), charge coupled devices (CCDs), liquid crystal displays (LCDs), and electronically controllable light sources. Results of the experiment with our optical correlator, performed with simulated sonar signals with a center frequency of 100 kHz and duration of 8 to 512 pulses (corresponding 13 jts -65 ms), show the possibility of recognizing a Doppler shift of 20 Hz. This Doppler shift corresponds to a target velocity of 20.7 rn/sec. Simulation results indicate that we can achieve significant correlation for a noisy (signal-to-noise ratio, SNR of 1) signal by using appropriate signal length (not less than 64 pulses). Our experiments demonstrate that we can perform .iO1O multiply accumulate operations (multiplication and summation) per second with the high parallel optical correlator, compared to iO6 multiply accumulate operations per second using a Pentium 133 MHz personal computer (PC).This new optical correlation scheme can provide solutions for overcoming the inherent shortcomings attributable to the low dynamic range of CCD, and the problem of compatibility caused by different pixel patterns between LCD and CCD by making use of high-quality optics and modern means of achieving uniform illumination.