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Abstract

A defect inspection method for three-dimensional shapes employs a difference is between a distance code obtained by scanning, a perfect work (a value indicating a rocking angle of a mirror), and a distance code obtained by scanning an inspected work, at each measurement position. Differences are stored for a matrix in which a linear direction of the irradiation and a direction of a moving locus of the irradiation are two orthogonal axes. The most frequent difference value among matrix elements in the linear direction of the irradiation is found at each rocking angle of the mirror. A matrix element having a difference that deviates from the most frequent difference value by more than a set value is found at each rocking position of the mirror. Thus, sections having distance codes that do not match distance codes of the perfect work even by relatively shifting the distance code data are detected and identified as defect candidates. The presence/absence of defects on the inspected work is determined on the basis of all the existing states of matrix elements as defect candidates.

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