Abstract

It is now well known that a modification of the diffraction-limited point-spread function is possible by using various types of amplitude apodization filter. A comparative study of the performance of optical systems apodized with a few commonly used amplitude filters has been made. The comparison has been made from the considerations of the diffracted field characteristics, namely, point-spread function, encircled energy factor, Strehl ratio, second-order moment, mean apodization ratio, two-point resolution, etc. The imaging characteristics of extended objects, both periodic and nonperiodic in various conditions of coherence, have also been compared with special reference to optical transfer function, generalized frequency response function, image contrast, etc. Attempts have been made to correlate the functional form of the pupil function to the performance of the apodized optical system in terms of the various diffracted fields and the imaging characteristic parameters considered. Finally, experimental methods to fabricate a few of these filters for superresolution, image processing, etc. are described.

© 1985 Optical Society of America