| 摘要 |
PURPOSE:To detect a foreign matter and a defect such as rust in the surface of a metal substrate. CONSTITUTION:Material 11 to be inspected such as metal substrate is irradiated with a detecting light 12 at the right angle to the direction X-X of rolling and from the direction inclined to the surface to measure the intensity of scattered light by a scattered light detection means 15 arranged above an inspection position A. Here, when there is no defect such as rust. much scattered light 14 attributed to fine irregularities formed on the surface part of the material 11 to be inspected during the rolling is permitted to impinge onto the detection means 15 and a signal thereof is at a HIGH level. When there is any defect such as rust, the defect checks the generation of the scattered light 14 to lower a signal from the detection means 15 significantly thereby enabling the detection of a foreign matter and the defect. |
