Apparatus for detecting the defects of a pattern with directional characteristics using a filter having arm sections of curved shape

摘要: An apparatus for detecting the defects composed of non-linear components a subject pattern, includes laser source illuminating pattern by beam, Fourier-transform lens projecting an information light from through spatial filter onto screen. The is placed on plane Fourier-transformed intercepting coherent having linear components, arm sections extending correspondingly to said normal outer periphery including curved circular or elliptical shape protruding toward intersecting point arms.