Patent ID: 8502988

Claim:
A pattern inspection apparatus comprising: a light source; a beam splitter configured to split a light emitted from the light source into a first optical path and a second optical path; a first optical system provided on the first optical path, the first optical system delivering the light to a first pattern and delivering a first reflected light from the first pattern; a second optical system provided on the second optical path, the second optical system delivering the light to a second pattern and delivering a second reflected light from the second pattern, the second pattern having an identical shape and dimensions to the first pattern, and the light delivered to the second pattern not overlapping with the light delivered to the first pattern; a polarization controller provided on at least one of the first optical path and the second optical path, the polarization controller controlling a polarization angle and a polarization phase, and the polarization controller performing a control so that an intensity of the first reflected light and an intensity of the second reflected light are substantially equal to each other; a phase controller provided on at least one of the first optical path and the second optical path, and performing a control so that a phase of the first reflected light and a phase of the second reflected light are inverted from each other; and a detector configured to detect a light produced by superposing the first reflected light and the second reflected light one upon the other in the beam splitter so that the first reflected light and the second reflected light are made to interfere with each other.