Incoherent imaging and spatial filtering systems may use illumination sources that are effectively periodic and discrete spatially (e.g., light-emitting-diode arrays or cathode-ray-tube rasters). We show that, despite the noncontinuous nature of such sources, linear-in-intensity imaging can, under certain conditions, be obtained. We model the source as a sampled continuous distribution and use Fourier optics methods to obtain a sampling condition that specifies the minimum permissible spacing between source points. This minimum spacing depends on the reciprocal of the smaller of the width of the object and the width of the imaging system’s coherent point-spread function. Relatively coarse sampling in the source plane is permitted in many cases of practical interest. We provide additional physical insight by examining the distributions (wave-amplitude distributions and transmittance function) in the pupil plane of the system.
© 1989 Optical Society of America
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