FLAW DETECTING METHOD AND DEVICE FOR PLATE-LIKE BODY

摘要

PROBLEM TO BE SOLVED: To provide a flaw detecting method and its device for a plate-like body capable of detecting a flaw having a fracture surface perpendicular to a principal plane without affected by a protective film stuck to the principal plane. SOLUTION: A light beam 6 irradiates the plate-like body 3 while an irradiation position by the light beam 6 is moved, and the flaw is detected based on a change of the light quantity transmitting the plate-like body 3 of the irradiated light beam 6 by this flaw detecting method and the device. The light beam 6 irradiates the plate-like body 3 so that the optical axis 101 lies nonperpendicularly to a principal plane 3a.