| 摘要 |
PURPOSE:To equalize the detection accuracy, by deflecting a scanning pattern drawn by a light beam which is made incident to a light beam focusing means for focusing a light beam onto the surface of a material to be inspected, to a shape being similar to an external shape of the material to be inspected. CONSTITUTION:A light beam 2 from a laser light source 1 is reflected by driving mirrors 9a, 9b of a polarization means 9, and reaches a reflector 11. The light beam 2 reflected by the reflector 11 is irradiated so as to form one coil- like uniform beam spot 14 extending over almost the whole circumference except a shadow part (part shown by a broken line in the figure) of a material to be inspected 3 through a convex lens 12. The light beam 2 scanned onto the surface of the material to be inspected 3 is reflected and is irradiated as a reflected ray 5 to a photoelectric converting element of a detector 7. Accordingly, when the material to be inspected 3 is moved in the axial direction, the reflected ray 5 can be obtained from almost the whole surface of the material to be inspected 3, and a strong or weak variation of this reflected ray 5 is inputted to a processing circuit 15, by which whether a defect exists on the surface of the material to be inspected 3 or not is detected. |
