Performance Evaluation of an Apodized Optical System with Polarization Masks

Abstract

It sometimes becomes necessary to modify the imaging characteristics of an optical system to achieve better performance for certain applications. The modification can be achieved by various means, and the usual practice has been to modify the amplitude and phase transmissions over different zones of the pupil of the optical system; such a modification is called apodization. The present paper reports a method of apodization in which three polarization masks are pláced at different orientations over the pupil of the optical system, which is illuminated with an elliptically polarized light beam. The performance of this apodized optical system has been investigated in terms of diffraction patterns and optical transfer functions by making use of the Jones matrix approach. It has been shown that, by suitably choosing the state of polarization of the illuminating beam and the orientation of the polarization masks, the performance of the optical system can be effectively modified. Further, with an analyser in the image plane, the diffraction pattern as well as the optical transfer function can be continuously modified for required roles.