Patent ID: 8908172

Claim:
A defect inspection device comprising: an illumination optical portion configured to illuminate, with illuminating light, an object to be inspected; a detecting optical portion illuminated by the illumination optical portion, and equipped with a plurality of detectors configured to detect components of scattered light scattered from the inspected object, each detector disposed in a different direction of azimuthal angle or in a different direction of angle of elevation with respect to a surface of the inspected object; and a signal processing portion configured to perform defect determinations as to a plurality of signals, based on the scattered light components from the inspected object detected by the detectors, respectively, such that the defect determinations are performed in parallel, based on gain adjustments and threshold value decisions, and configured to extract defects based on results of the gain adjustments and defect determinations, wherein the signal processing portion includes: a signal combining portion having a plurality of signal combining units, and configured to perform, in parallel, respective gain adjustments on a plurality of signals, the signals being based on the scattered light components received from the inspected object and detected by the plurality of detectors, wherein each signal combining unit is configured to perform gain adjustments respectively on the signals based on the scattered light components received from the inspected object and detected by the detectors, and wherein the signal combining units perform the gain adjustments using respectively different values of gain; a defect decision portion having a plurality of defect decision units, and configured to perform, in parallel, defect determinations based on a preset threshold value, on the signals on which the gain adjustments have been made by the signal combining portion, wherein each defect decision unit is configured to perform defect determinations respectively on signals on which the gain adjustments have been made by the signal combining portion, and a result combining portion configured to combine results of the defect determinations made by the defect decision portion and configured to extract defects.