Patent ID: 7417720

Claim:
A defect inspection method of a defect inspection apparatus including a housing, wherein the housing accommodates a laser beam source, a beam deflection mechanism enabling a beam emitted from the laser beam source to be reflected so that the beam travels in a direction almost parallel to the beam emitted form the laser source, a beam expander for converting the beam to a parallel beam having a larger cross-sectional area, an objective lens, through which the parallel beam is reduced and applied to the surface of a sample and a convergence lens, the method comprising the steps of: splitting the parallel beam in a light passage from the beam expander to the objective lens into at least two split parallel beams; further dividing at least one of the split parallel beams into at least two divided parallel beams; observing a beam intensity profile of the cross-section of a first of the divided parallel beams; converging a second of the divided parallel beams with the convergence lens; detecting a position of a spot image converged with the convergence lens; and, controlling the beam deflection mechanism and the beam expander on the basis of either or both of information of the cross-sectional diameter of the beam and information of the beam position displacement.