APPARATUS FOR INSPECTING AN OBJECT BY LIGHT

摘要

An apparatus for determining the average size of fundamental patterns contained in a given region of an object to be inspected, which includes Fourier transform means for producing output data corresponding to a Fourier transform pattern image of the given region of the object, and processor means for processing the output data to provide the actual pattern size information. The Fourier transform means includes a Fourier converter for providing the output data corresponding to Fourier transform patterns. The processor means includes an extractor coupled to the Fourier transform means for extracting a single magnitude data (In) representing the order n of spatial frequency component (e.g. 200) from the output data, the magnitude of the order n component changing with variation (e.g. DELTA aH) of the size of patterns; and a data processor coupled to the extractor for determining the average size of patterns in the given region according to the single magnitude (In) and providing the actual pattern size information indicating the averge size of the patterns.