Patent ID: 7487049

Claim:
A surface inspection method for detecting contaminated particles or defects existing on a surface of an object to be inspected or inside near the surface, by using an object to be inspected moving stage for moving the object to be inspected, a pulse laser light source for conducting pulse oscillation repetitively in time, illumination means for irradiating an illumination spot having a predetermined size on the surface of the object to be inspected with pulse light supplied from the light source, scattered/diffracted/reflected light detection means for detecting light generated by scattering/diffracting/reflecting the irradiating light in the illumination spot and converting the light to an electric signal, A/D conversion means for converting the electric signal to digital data, and particle size calculation means for calculating a size of a contaminated particle or defect on the basis of the digital data, wherein the A/D conversion means samples the electric signal at substantially constant sampling intervals, and the sampling interval is determined so as to be associated with a pulse oscillation repetition period of the laser light source.