Patent ID: 8452074

Claim:
A pattern inspection apparatus comprising: a light source; a stage configured to mount thereon a substrate with a pattern formed thereon; a first laser measuring unit configured to measure a position of the stage by using a laser beam; a sensor configured to capture a pattern image obtained from the pattern, formed on the substrate, irradiated by light from the light source; an optical system configured to focus the pattern image on the sensor; a second laser measuring unit configured to measure a position of the optical system by using a laser beam; a correction unit configured to correct a captured pattern image by using a difference between the position of the stage and the position of the optical system; and an inspection unit configured to inspect whether there is a defect of the pattern by using a corrected pattern image, wherein the correction unit corrects the captured pattern image per subpixel by using a Whittaker-Shannon interpolation formula which uses a sampling interval obtained by Nyquist condition, and the sampling interval L is obtained by an equation of L≦λ/(4NA)*M using a maximum aperture angle NA at a side of the substrate in the optical system, a wavelength λ of the light from the light source and a magnification M of the optical system.