| 摘要 |
PURPOSE:To perform measurement speedily and accurately by providing a moving measurement part with plural observation parts consisting of a light source part and a photodetection part, and regarding the intersection of irradiation light beams and detecting large/small relation in distance from the photodetection order of reflected light beams from a body to be measured. CONSTITUTION:There are plural, for example, two observation parts provided so as to reflect irradiation light from a light source 6 by a body 7 or 13 to be measured and then photodetect the reflected light by a photodetecting element 7. Namely, the 1st and the 2nd observation parts 11 and 12 are provided at specific distance l from the moving measurement part 10 which moves on an (x) axis and at the opposite side to the moving direction side. They are slanted at specific angles theta1 and theta2 to the (x) axis and irradiation light beams cross each other at a point P at distance (d) from the (x) axis. Then, the measurement part 10 is moved and the observation parts 11 and 12 photodetect the reflected light from the body 13 to be measured; and the observation part 11 when the distance to the measurement part 13 is shorter than the distance (d) or 12 when larger detects the reflected light earlier. |
