APPARATUS FOR DETECTING INTERNAL DEFECT OF STRUCTURE

PROBLEM TO BE SOLVED: To provide an apparatus which can conduct quantitative evaluation, reduce cost required for inspection and inspect defects which are deeper than by prior art. SOLUTION: This apparatus detects internal defects of a structure by exposing the structure to light. The apparatus includes an infrared light source 21 for radiating infrared beams to the overhead bridge 22, an infrared radiation time controller 25 connected electrically to the infrared light source 21, an infrared camera 26 connected electrically to the infrared radiation time controller 25 for picking up images of the structure illuminated by the infrared light source 21, an image storage device 27, connected electrically to the infrared camera 26 for storing images picked up by the camera 26, and an image- analyzing device 28 electrically connected to the infrared irradiation time controller 25 and the image storage device 27 for analyzing images stored in the image storage device 27.