| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a surface flaw without being affected by displacement such as backlash of an inspecting object even if the displacement occurs in a range exceeding the uneven shape of the flaw due to the conveyance of the inspecting object.SOLUTION: When a surface flaw of a long-sized inspecting object 12 is inspected over the whole length of the inspecting object 12, a plurality of distance measuring means (21 and 22) are closely disposed in the relative moving direction. The distance measuring means (21 and 22) measure the distance to the surface of the inspecting object 12 while relatively moving in the longitudinal direction of the inspecting object 12 maintaining a certain distance from the central axis of the inspecting object 12. The existence of the surface flaw 12A of the inspecting object 12 is detected on the basis of a distance profile of the longitudinal direction of the inspecting object 12 that is measured by the plurality of distance measuring means (21 and 22). |
