Inspection apparatus

When it is tried to detect a microscopic defect, it is desired that the width of the above-mentioned illuminated region in the minor axis direction should be short. In the related art, although an illuminated region is formed by converging light by some means, it is not easy to form an illuminated region with a narrower width. This is because various aberrations possessed by optical elements themselves used for convergence, aberrations possessed by other optical elements disposed on optical paths, assembly errors, and the like have undesired influence on the formation of linear illumination. In the related art, sufficient consideration has not been paid to the above points. The present invention is characterized in that it includes a system for changing the wavefront of light.