| 摘要 |
PROBLEM TO BE SOLVED: To provide an edge detection method which enable the position detection with high accuracy from a light intensity distribution on a light-receiving surface by a Fresnel diffraction, and its device. SOLUTION: A light intensity change at an initial build-up part of the light intensity distribution on the light-receiving surface of a line sensor by the Fresnel diffraction of a monochromatic parallel light is approximated with a hyperbolic second function sech (x). A light-receiving intensity for each light-receiving cell of the line sensor is analyzed by using the hyperbolic second function. Especially, each light receiving cell having the light receiving intensities which place a standard light receiving intensity [0.25] between is obtained. For the light-receiving surface of each light receiving cell, a light-receiving position which is to have the light-receiving intensity is calculated by the hyperbolic second function approximating the light intensity distribution. From the light receiving position thus calculated, a position which is to have the standard light-receiving intensity is obtained as an edge position of the above shield by interpolation calculation. COPYRIGHT: (C)2004,JPO
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