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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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The photocontrolled millimeter-wave (MMW) antenna is an alternative approach to the phased array. It offers a high potential to decrease fabrication cost. We describe a new MMW scanning antenna controlled by light. The basic antenna element is a semiconductor plate containing a photoinduced plasma grating (PIPG). By changing the grating period and rotating the grating, the device is able to scan a MMW beam in two dimensions. To enhance antenna efficiency, we use an antenna design that takes advantage of the reflectance of the MMW mirror behind the semiconductor plate. We found that the pulse duration of the pumping light can strongly affect the antenna's output. Our calculations demonstrate that diffusion is responsible for decay of antenna efficiency.