JPS5479693A - Wire body surface defect detector - Google Patents

Abstract

PURPOSE:To obtain a device capable of detecting defects without being influenced by linear velocity or linear vibration, by receiving the light reflected from a defective part on wire body surface after being projected from one optical fiber with the other optical fiber. CONSTITUTION:When there is no defect in the wire body surface, the projected light from end part 5B of outer layer optical fiber 5 runs along an optical path 7 and is reflected by a concave mirror 3, and then runs along an optical path 8 and is reflected by surface 9 of a wire body, thereby advancing at the reflection angle theta' equal to the incident angle theta, so that almost no light reaches the end part 6A of inner layer optical fiber 6. If there is a defect in the wire body surface, the light running along the optical path 8 is reflected by point 9' on the surface of defective part 2, and returns along an optical path 11, and is reflected by the concave mirror 3, thereby entering the end part 6A of the inner layer optical fiber 6 through the optical path 12, finally reaching a photo detector 16. Furthermore, even if there is linear vibration, the defect may be detected without being influenced by such vibration.