Improvement of point spread function (PSF) using linear quadratic aperture

Abstract

Since each of the modulated linear and quadratic apertures gives better resolution as compared with that obtained in case of circular aperture. Hence, we believe that a combination of both linear and quadratic multilayer concentric circular aperture will give a further improvement in resolution and contrast. Consequently, the following two models are assumed. The 1st aperture model is composed of successive quadratic, linear, and constant circular transmission segments from the center. In this model, the central quadratic distributed segment from the aperture is chosen in order to attenuate the low spatial frequencies. The 2nd aperture model is composed of four concentric segments. In this aperture, starting from the center, the 1st segment is dark central disk followed by a higher order, 6, distribution, the next is linear, and the last has constant transmission segment. In this model, further spatial frequency attenuation is attained by the selection of the central dark disk followed by the 6 distribution. The point spread function (PSF) of the described apertures is computed and compared with the corresponding annular and circular apertures. In addition, the coherent transfer function of the confocal microscope is computed using the two models of multilayer arrangement. The effect of the pinhole diameter upon the PSF of a standard CSLM using the two models of apertures is discussed. A MATLAB code is organized to perform all the numerical computations and plots.