Authors: PD Lin CS Liu
Publish Date: 2010/12/17
Volume: 102, Issue: 1, Pages: 243-249
Abstract
The Modulation Transfer Function MTF is a measure of an optical system’s ability to transfer contrast from the specimen to the image plane at a specific resolution It can be computed either numerically by geometrical optics or measured experimentally by imaging a knife edge or a bartarget pattern of varying spatial frequency Previously MTF accuracy was generally affected by the size of the mesh on the image plane This paper presents a new MTF computation method based on the irradiance model without counting the number of rays hitting each grid To verify the method the MTF in the sagittal and meridional directions of an axissymmetrical optical system is computed by both the raycounting and the proposed methods It is found that the grid size meshed on the image plane significantly affects the MTF of the raycounting method sometimes with significantly negative results The proposed irradiance method is immune to issues of grid size The CPU computation time for the two methods is approximately the same
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