APPARATUS FOR MULTIPLEXED IMAGING USING OPTICALLY-GENERATED KRONECKER PRODUCTS

A new type of fully-multiplexed imaging device is described for use at wavelengths where efficient focal plane array detectors are unavailable. It shares some properties in common with the familiar technique of cycle-redundancy (i.e. Hadamard transform) imaging, but many of its features and capabilities are unique. Some of these characteristics are, first, the new approach employs image encoding masks that are both transmitting and reflecting, thereby increasing optical efficiency, and second, the technique requires only 2.sqroot.N encoding masks to image a field of N pixels, a dramatically smaller number than that needed (.about.2N) by traditional methods. Dual complementary inputs are used for first-order passive rejection of radiation background interference. The resulting image spatial resolutions along two coordinate directions are completely independent of each other. The measured image is formed by a convergent tiling of the image plane, quite unlike conventional raster scanning. In principle, the technique is capable of versatile adaptation to a wide variety of imaging and target discrimination tasks in infrared and microwave remote sensing, astronomy and surveillance.