| 摘要 |
PURPOSE:To increase the permissible range of the slant angle of a body to be measured by using outside parts of convex lenses for projection and photodetection except part of their inside parts. CONSTITUTION:Light from a light source 1 is projected through the outside part 2b of the projection lens 2 and an aperture 6a, and reflected light R of the projection beam P from the body X to be measured is passed through an aperture 6b and the outside part 3b of the photodetection lens 3 to form an image on a photodetecting element 4. Then, the light shield part 5 having the apertures 6a and 6b shields internal half parts 2a and 3a of the convex lenses 2 and 3 for projection and photodetection. Consequently, the angle at which a regular reflection component is incident through the photodetection lens 3 increases to widen the permissible range of the slant angle of the objective body X without varying the distance l0 between the lenses 2 and 3, and a sensor is reduced in size. |
