| 摘要 |
<p>PROBLEM TO BE SOLVED: To simplify an apparatus, to reduce its costs and to prevent its failure and its trouble by a method wherein a laser beam is expanded by a rotary reflecting body so as to continuously scan a detection region on a definite plane or on a definite line. SOLUTION: A rotary reflecting body 2 can be turned around a shaft 21 at its axial center, and its circumferential face 22 is formed of a plurality of plane reflecting plates. A reflecting sheet 3 is used to reflect a laser beam 4, and it is attached to, and installed at, a moving object, to be detected, in advance. The rotary reflecting body 2 is turned, and the laser beam 4 is radiated from a laser transmitter-receiver 1 toward its circumferential face 22. The laser beam 4 is reflected by the circumferential face 22 of the rotary reflecting body 2 so as to be expanded, and it continuously scans a detection region on a definite plane or on a definite line. When the moving object creeps into the detection region, the reflecting sheet 3 which is attached to, and installed at, the moving object reflects the laser beam 4. Then, its reflected beam is received by the laser transmitter-receiver 1, and it is detected that the moving object has crept into the detection region.</p> |
