Patent ID: 8654333

Claim:
A surface inspection apparatus comprising: a light source for applying a detection beam to a sample of a film form; a light receiver, having plural photoelectric cells arranged in a width direction of said sample, for receiving output light transmitted or reflected by said sample; a defect detector for detecting a defect on said sample according to an output signal output by each of said photoelectric cells; and a sensitivity corrector for correcting sensitivity of said photoelectric cells, wherein said sensitivity corrector is constituted by plural sensitivity correctors for correcting sensitivity of respectively one of said photoelectric cells corresponding thereto, to keep a signal difference of said output signal between said photoelectric cells as small as a predetermined value or less, and wherein said sensitivity corrector includes: plural light valves each of which is disposed upstream of one of said photoelectric cells; and a transmission control unit for setting transmittance of said light valves by applying voltage thereto.