Imaging with Low-Redundancy Arrays
A conventional imaging system, consisting of a collection of lenses or mirrors with clear apertures, provides non-uniform coverage of the spatial spectrum of an incoherent object.1,2 Stated another way, a certain spatial-frequency redundancy is inherent to such a system, with low spatial frequencies being weighted more heavily than high spatial frequencies. In this paper we propose that it may sometimes be desirable to destroy this redundancy by inserting a complicated mask in the exit pupil of the system, thereby allowing the images to be formed with a multi-element interferometer. With a proper choice of mask geometry, the spatial frequency redundancy can be minimized or eliminated. The destruction of redundancy will be shown to be advantageous if the optical elements are aberrated and if post-detection image processing may be applied to improve image quality. We emphasize at the start that all arguments to follow apply only for spatially incoherent objects.
KeywordsSpatial Frequency High Spatial Frequency Inverse Filter Optical Transfer Function Vector Separation
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