Optical noise and temporal coherence

Abstract

Previous articles have been devoted to the study of optical noise as a function of spatial coherence. The present one completes this study by considering temporal coherence. Noise arising from defects in the pupil plane and affecting the high spatial frequencies of an image is notably reduced by white-light illumination. Temporal coherence has little effect on noise arising from defects in the object plane. However, impulse noise due to small isolated defects is reduced in size. Physical arguments are presented to explain these phenomena and a mathematical study of partially coherent imaging in the presence of random defects is given.