Patent ID: 6580502
Filing Date: 2003-06-17
Classification: G01N,G02B

Abstract:
An appearance inspection method for detecting a fault of an inspection object having pattern regions by comparing an image acquired by imaging said pattern regions arranged in a predetermined direction on said inspection object with an image of a pattern arranged at a corresponding position of another inspection object, comprising the steps of:radiating rays of light by illumination means for radiating the rays of light having at least two wavelength bands; changing the direction of the rays of light from said illumination means by a beam splitter; focusing said rays of light, the direction of which is so changed on the surface of said inspection object, through a single fixed optical system having such chromatic aberration as a to focus the rays of light on positions corresponding to said wavelength bands; separating the rays of light of said two wavelength bands reflected from the surface of said inspection object into two directions by a half mirror through said optical system and through said beam splitter and causing one of the rays of light so separated to travel towards first wavelength selection means and the other towards second wavelength selection means; allowing one of the rays of said at least two wavelength bands to pass through said first wavelength selection means and the other of the rays of light of at least two wavelengths bands to pass through said second wavelength selection means; receiving the rays of light passing through said first and second wavelength selection means by at least two imaging means, respectively, and simultaneously imaging the image of said pattern regions by said wavelength bands, respectively; synthesizing the taken image data; and detecting a fault of said inspection object by comparing the image of each region of said synthetic image with the image of a pattern arranged at a corresponding position of other inspection object.