Space-Variant Image Formation*

Abstract

The application of optical transfer theory to the process of image formation requires that the image-forming system be linear and space invariant. In a space-invariant system, the point image retains its shape while the point source explores the object plane. The purpose of this paper is to investigate image-forming systems which are linear but space variant. Such systems may exceed performance limitations which are inherent in linear space-invariant systems. A method for experimentally determining space variance is devised. The degree of space invariance is defined and evaluated for several examples of space-variant systems.