Patent ID: 7821644

Claim:
An inspection apparatus for inspecting a specimen with patterns formed thereon comprising: a specimen stage for holding said specimen; a light source; an illumination optic for illuminating an area on said specimen with said light source; a diffuser; a polarizing beam splitter; an objective lens; a quarter waveplate arranged between said polarizing beam splitter and said objective lens; an imaging optic for forming an image of said specimen; and a photoelectric conversion image sensor for obtaining images of a part of said illuminated area on said specimen, comprising an array of channels in a longitudinal direction, each channel comprising pixels, wherein an illumination beam of light rays emitted from said light source is irradiated on the specimen held by said specimen stage via said diffuser, said polarizing beam splitter, said quarter waveplate and said objective lens, wherein a reflection beam from said specimen is led to said imaging optic by way of said objective lens, quarter waveplate and polarizing beam splitter so as to image said specimen on said image sensor, and wherein the direction of the illumination beam from said light source incident on said polarizing beam splitter is substantially parallel to said longitudinal direction of said array of channels of said photoelectric conversion image sensor projected on said polarizing beam splitter, and polarization directions in the center and at opposite ends of said photoelectric conversion image sensor view field, respectively, are identical with one another to reduce dependency of inspection sensitivity on channels of said photoelectric conversion image sensor so as to improve sensitivity of said inspection.