A system including a microscope and an inspection apparatus in which an objective lens having a large numerical aperture is used for detecting a defect existing inside a sample. A light source apparatus produces linearly polarized light. The polarization maintaining fibers optically coupled to the light source apparatus project the linearly polarized light onto the sample surface as an illumination beam of P-polarized light at an incidence angle substantially equal to the Brewster's angle of the sample. The scattered light generated by the defect existing in the sample is emitted from the sample and is collected by the objective lens whose optical axis is perpendicular to the sample surface. Since the illumination beam of P-polarized light is projected at the incidence angle equal to the Brewster's angle of the sample, no surface reflection occurs and it is possible to use the objective lens having a large numerical aperture.