| 摘要 |
PROBLEM TO BE SOLVED: To omit tilt adjustment in a position adjusting by separating a laser beam transmitting through a lens into two luminous flux and providing two or above of means which impart optical path difference to the luminous flux existing in the space as far as a photodetector. SOLUTION: A luminous flux 2j transmitted through a beam splitting surface 15a is reflected by a total reflection surface 15b, and is retransmitted through the beam splitting surface 15a, and passes through the light splitting surface 15c, and is reflected by the total reflection surface 15d, and passes again through the light splitting surface 15c to be irradiated on the photodetector 16 on a position rear from a focus. The optical path difference between a luminous flux 2a and a luminous flux 2j, first becomes a total of p+q by that it is given first by (q) between the beam splitting surface 15a and the total reflection surface 15d. The sizes of the luminous flux 2a and the luminous flux 2j on the photodetector 16 are proportional to p+q, and a gap (r) becomes r=q-p. Thus, by selecting the values of (p) and (q), the matter independently setting of the sizes and the gap of two luminous flux on the photodetector 16 becomes possible, and the gap is reduced without changing the sizes of the luminous flux 2a and the luminous flux 2j. |
