| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent the influence of noise due to return beams. <P>SOLUTION: A 1/4 wave plate 21 positioned at one of optical paths A1 and B1 of parallel beams A1 between a collimate lens 17 and a rising mirror 19 and parallel beams B1 between the rising mirror 19 and an objective lens 23 is positioned inclined with respect to optical axes A and B, so as to reflect the return beams to a position deviated from the light emitting point of a laser element 11 and the light receiving part of a light receiving element 27. <P>COPYRIGHT: (C)2003,JPO |
