| 摘要 |
PROBLEM TO BE SOLVED: To perform front and rear positioning of a tip of a hole drilling rod and a rear end of a guide cell easily and simultaneously. SOLUTION: Two laser projectors, namely, a first laser projector 3 and a second laser projector 5 having different laser beam colors are simultaneously used. A laser beam 6 from the first laser projector 3 is directly irradiated as spot light using a digging hole target point 8 on a digging face such as tunnel facing as an aiming point, and at the same time, a laser beam 7 from the second laser projector 5 is moved so that it becomes scanning light along a tangential line 11 with which a rear end target point for the rear end of the guide cell 4 holding the hole digging rod 1 comes into contact to align the tip of the hole digging rod 1 with spot light and align the rear end of the guide cell 4 with the rear end target point along the scanning light.
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