Solving the Out-Of-Focus OTF Reduction Using a Phase Only Filter and Fuzzy Logic Reasoning

The problem of frequency response degradation while stepping out of the focal plane of an optical setup is well known. In this work the authors suggest a novel method for decreasing this effect. The main principle is to assign different weights to different out-of-focus planes and design a phase only filter for each plane, then combining the filters with respect to the weights. The weights of the different planes increase as the distance from the focal plane increases and the exact weights are determined by a fuzzy logic inference engine. The fuzzy logic tool grades the different weighing sets according to the average width of the optical transfer functions and according to the deviation between function's widths.