Patent ID: 7602487

Claim:
A surface inspection apparatus that comprises: a light source that emits inspection light; an inspection head that is inserted inside a cylindrical body, which is an inspection object, that, while rotating around an axis of the cylindrical body and moving in the axial directions, projects the inspection light emitted from the light source to an inner circumferential surface of the cylindrical body and receives the light reflected thereby; and a photoelectric converting means that outputs a signal in accordance with the intensity of the reflected light received by the inspection head; and that generates a two dimensional image that corresponds to the inner circumferential surface based on the signal output by the photoelectric converting means; further comprising: a signal processor extracting frequency components, which correspond to fluctuations in the intensity of the reflected light caused by a deviation between the axis and a center line of the cylindrical body, from the signal output by the photoelectric converting means; and a light source controller controlling the light source so that the intensity of the inspection light emitted from the light source varies with the differential between a prescribed reference value and the frequency components extracted by the signal processing means, wherein the signal processor extracting frequency components within a prescribed range that includes frequency components that correspond to the fluctuations and omits frequency components that correspond to a defect of the inner circumferential surface.