Super-resolution by pupil plane phase filtering

Abstract

Resolution capability of any optical imaging system is limited by residual aberrations as well as diffraction effects. Overcoming this fundamental limit is called super-resolution. Several new paradigms for super-resolution in optical systems use 'a posteriori' digital image processing. In these ventures the three-dimensional point spread function (PSF) of the lens plays a key role in image acquisition. A straightforward tailoring of the PSF can be performed by appropriate pupil plane filtering. With a brief review of the state-of-art in this research area, this paper dwells upon the inverse problem of global optimization of the pupil function by phase filtering in accordance with the desired PSF.

Toraldo filters with concentric unequal annuli of fixed phase by evolutionary programming

“…Also, formation of merit function should correctly reflect goals of optimization so that one can aim for problem-specific useful solutions. The merit function used in our earlier reports [38,39] did not directly incorporate provisions for setting desired targets for width of the central lobe and required field size. Few analytical studies, reported earlier, formulate the problem as a search for the pupil function in accordance with prespecified location for zeros in the point spread function.…”

“…On the other hand, Liu and Wang used a constrained global optimization technique in the design of three-zone, phase-only, and amplitude-only optical pupil filters. We have reported earlier [38,39] our adaptation of evolutionary programming for the purpose, where we incorporated dynamic merit function to overcome stagnation problems in the optimization procedure, but the study was restricted to the case of equal area zones.…”

Engineering of Aberrated PSF by Asymmetric Apodization with the Complex Shaded Aperture

“…Optical aberrations reduce the overall performance of an optical system [30,31]. Aberrations can be reduced by using an optical element with a high optical transmission function [32][33][34][35][36][37][38][39][40][41][42]. Traditionally, apodization of the exit pupil of the optical system has been aimed at producing a high-quality output or increasing imaging qualities.…”