| 摘要 |
A surface inspection apparatus includes a light source for applying a detection laser beam to a film sample. A light receiver has plural photomultiplier tubes arranged in a width direction of the film sample, for receiving output light reflected by the film sample. A defect detector detects a defect on the film sample according to an output signal output by each of the photomultiplier tubes. A sensitivity corrector sets sensitivity of the photomultiplier tubes to process an output of the light receiver for output noise suppression. Specifically, the sensitivity corrector determines a set sensitivity of the photomultiplier tubes by correcting a sensitivity characteristic thereof for abnormality detection, to keep a sensitivity difference between the photomultiplier tubes as small as a predetermined value or less. Furthermore, plural light valves upstream from the light receivers are controlled by the sensitivity corrector for their transmittance.
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