| 摘要 |
PROBLEM TO BE SOLVED: To provide a range finder for reducing a cost by achieving a highly accurate measurement with less temperature dependency and at the same time forming an image-forming lens of a plastic lens. SOLUTION: A protrusion 23a is offset by an offset distance E toward a same side at a line (X axis) including a light axis interval B0 . Each point of a lens 20R (20L) causes a thermal inflation for a lens supporting plate 16a with the protrusion 23a as an anchoring point due to a temperature change. However, either axial center is displaced in a same direction by a same distance on X axis, thus preventing the light axis interval based on the thermal inflation of the lens 20R (20L) itself from occurring. The light axis interval is uniquely determined in proportional to the thermal coefficient of expansion and the temperature change of the lens supporting plate 16a. As a result, a temperature can be compensated and a high-accuracy ranging finding can be achieved due to the improvement in temperature characteristics. Also, a plastic lens with a large thermal coefficient of expansion can be used, thus reducing cost. |
