| 摘要 |
PROBLEM TO BE SOLVED: To suppress leakage of stray lights from a reflection-measuring instrument which detects an external body by receiving the reflected light of a light beam irradiating the outside. SOLUTION: A partition wall 112, which has a partition wall opening 118, is provided on the optical path of nearly parallel laser light reaching a polygon mirror 30 from a lens unit 10 via a reflecting mirror 20. The partition wall 112 allows the laser light to pass through the partition wall opening 118 and cuts off stray light generated more closely to the lens unit 10 than to the partition wall opening 118 at the periphery of the partition wall opening 118. The peripheral edge part of the partition wall opening 118 is pointed toward the optical path of the laser light. Consequently, the stray light is generated more closely to the lens unit 10 than to the partition wall 112 can effectively be cut off, and the generation of new stray lights at the peripheral edge part of the partition wall opening 118 can be suppressed.
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