Patent ID: 7936452

Claim:
An inspection apparatus comprising: a light projecting unit configured to project linear light on a surface of an object to be inspected; a first light receiving unit and a second light receiving unit configured to receive scattered light of light projected on the surface by the light projecting unit, which is generated by the surface; and a controller configured to relatively scan the light projecting unit, the first light receiving unit, and the second light receiving unit along the surface while maintaining a positional relationship between the light projecting unit, the first light receiving unit, and the second light receiving unit and determine the presence/absence of a foreign substance on the surface based on intensity distributions of signals output from the first light receiving unit and the second light receiving unit, the controller causing the inspection apparatus to perform foreign substance inspection a plurality number of times while changing a positional relationship between a tentative first start position at which the first light receiving unit starts scanning and a tentative second start position at which the second light receiving unit starts scanning, calculating an overlapping degree between an intensity distribution of a signal output from the first light receiving unit and an intensity distribution of a signal output from the second light receiving unit for each of the plurality of foreign substance inspections, and determining a scanning start position of each of the first light receiving unit and the second light receiving unit to inspect the surface of the object based on the positional relationship between the tentative first start position and the tentative second start position which exhibits a maximal overlapping degree among the plurality of calculated overlapping degrees.