COHERENCE REQUIREMENTS, TRANSFER FUNCTION AND NOISE PERFORMANCE OF A PARTIALLY COHERENT OPTICAL PROCESSOR

This dissertation is a theoretical study of partially coherent optical information processing. We use Wolf's theory of partially coherent light to develop a transformation formula for the mutual intensity function passing through an ideal thin lens. Later, we develop a general formula to describe the characteristics of a partially coherent optical processor. The quantitative analysis of the temporal and the spatial coherence requirements for three of the most important processing operations, image deblurring, image subtraction, and signal correlation detection, are investigated. We also establish the quantitative relations between processed image quality and the degree of coherence, such that the spectral bandwidth and the extent of the light source can be adequately selected for a given processing operation. The calculation results indicated that the coherence requirements for image subtraction are more stringent than those of the other two processing operations.;The quantitative relationships between the noise performance, depicted by the signal to noise ratio at the output plane, with respect to the temporal and the spatial coherence, respectively, are developed. A special emphasis is given to the cases when the noise is present at the input or at the Fourier plane. The results obtained are suitable not only for low frequency input, but also for high frequency signals. Generally speaking, a consistently better noise performance is expected for systems employing spatially incoherent illumination than for systems using a temporally incoherent light source.;Finally, we stress that the formulas and the conclusions obtained in this dissertation are rather general and may be applied to any partially coherent optical processing system.;We also develop the relations that illustrate how the apparent transfer function depends on the temporal and spatial coherence of the light source. The criteria based on the apparent transfer function are obtained to evaluate the resolution of the processor. It is shown that the modulated transfer function is less dependent upon the temporal coherence as compared to its relationship with the spatial coherence.