Development of the high speed inspection system of defects inside concrete

Mikami, Katsuhiro; Kurahashi, Shinri*; Kitamura, Toshiyuki*; Hasegawa, Noboru; Okada, Hajime; Kondo, Shuji; Kotyaev, O.*; Shimada, Yoshinori*; Kawachi, Tetsuya

A lot of infrastructure constructions were built in the 1940s and 1950s in Japan and these decrepitude are seriously concerned that leading to a serious accident. Recently, a novel inspection method using laser systems which consists of impact laser and detection laser, is energetically developing because of its significant advantages. A role of the impact laser is to induce the vibration on concrete walls by the high energy laser pulse behaving like hammering. Then, the detection laser set in laser differential interferometer that which detects the vibration of the concrete surface. For putting into actual utilization, the inspection speed which is about several ten meters per night should be improved for the exceedingly-long train-tunnels. The inspection speed of impact laser and detection systems is required a high-frequency measurement. In this study, we developed a new prototype inspection system to realize high speed inspection for defects inside concrete.