| 摘要 |
PURPOSE:To make crack generation clear at a glance by picking up an image of the deformation of a grating-shaped light beam formed on an object of measurement, computing and digitizing the obtained output and comparing it with last observation data and deciding whether or not a crack is generated, and displaying its position on a display if the crack is generated. CONSTITUTION:The object A of measurement such as a concrete pole is moved up and down, and right and left by using a moving device 3 while loaded, and grating-shaped interference fringes formed by projecting the light from an irradiation device 1 are picked up by an image pickup device 2, whose result is inputted to an arithmetic unit 4. At this time, there is a deformation place B in the interference fringes, the unit 4 digitizes its output signal and data on the place B among data which are obtained by last observation is read out of a storage means 5 to compare both data with each other, and it is judged whether or not a crack is generated from whether or not both data match with each other. When they do not match, a graphic drawing device 6 is used to give a mark C for the crack on the display or recording paper. Thus, the need to put the face close to the object of measurement is eliminated and detection is performed in safety.
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