SNR in photocounting images of rough objects in partially coherent light.

Image irradiance distributions from objects illuminated with partially coherent, quasi-monochromatic light, viewed against a spatially uniform background and received with a photosensitive detector are analyzed. A general expression for the SNR at the detector output is obtained as a function of the coherence of the illuminating light, the object surface roughness, the width of the telescope point spread function, and the aperture and integration time of the detector. The expression is evaluated for several limiting cases of coherence of illumination and of object surface roughness.