Pattern detector.

摘要

A pattern detector according to the present invention adopts a processing method wherein means is provided anew with which the intensity distribution of light reflected from or transmitted through an illuminated specimen is photoelectrically converted, and a pattern position is detected at high speed from the ratio between the primary moment and integral value of a detection signal thus derived, whereupon a symmetry calculation is executed within a narrow range around the detected value, whereby the pattern position is found fast and precisely.