| 摘要 |
PURPOSE:To find the position of an excavator even in a curved tunnel by providing a beam oscillator, a rotating prism, and encoder, a photodetector and a reflection mirror at the position to cross at right angles to a beam projecting plane to cross at right angles to an axis of rotation of the rotating prism. CONSTITUTION:Laser beams L1 projected horizontally from the laser oscillator 14 are made incident L2 on the center of the incident surface 10a of the rotating prism 10 via a fixed prism 13 and a perforated mirror 15. Next, the laser beams are enlarged sectorally via a semicylindrical lens 12 from the outgoing surface 10c and directed to the outside of a box body 1. Then, the surface laser beams are scanned in accordance with rotating motion of a rotary table 5, the prism 10 and the lens 12. Further, the laser beams reflected on a corner cube 19 are photodetected by the photodetector 17 via an optical path L4 or L4', L5, L6 almost contrary to the above. The photodetector 17 outputs a detected signal to the rotary encoder 4 when photodetecting the beams and the encoder 4 detects an angle of rotation from the reference direction of the prism 10 when receiving the detected signal and outputs the electrical signal to an indicator.
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