| 摘要 |
PURPOSE:To enhance measuring accuracy and to simplify a system, by scanning the entire peripheral wall surface of a tunnel crossing the longitudinal direction of the tunnel at a right angle by laser beam and detecting the scattering beam therefrom by one condensing lens and one light receiving means. CONSTITUTION:The inspection part 1 of this apparatus is mounted on a vehicle T running in a circular tunnel having a diameter D as a body to be inspected along the longitudinal direction thereof. Then laser beam is oscillated by a laser oscillator 2 so that an optical axis comes to the center axis of the tunnel and the mirror 4b supported by a mirror holder 4a is rotated at a high speed by a moor 3 to perform the rotary scanning of the wall surface 9 of the tunnel by said laser beam in a vertical direction. Further, the scattering beam from the wall surface 9 of said beam is received by the condensing lens 5 and light receiver 6 arranged so as to be spaced apart by a predetermined distance from the mirror 4b. Furthermore, the beam reflected by the mirror 4b is detected by a rotation detection sensor 8 through a half mirror 7 and operated by a processing circuit to detect the position of a crack.
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