| 摘要 |
PROBLEM TO BE SOLVED: To efficiently reflect light by controlling light that is emitted from a light source to a parallel light with an axis (c) of an optical system. SOLUTION: A line segment lp in a diametric direction along a lens surface Lp is a line segment on a straight line that orthogonally crosses the axis (c) of the optical system, the focus of a curve rl in the diametrical direction along an inner reflection surface Rl is located at a point p0 on a light source, the distance from the axis (c) of the optical system of one end point p1 of the curve rl is equal to or larger than a radius that is required for installing the light source, the other end point p2 of the curve rl is located at the light source side from the segment lp on the straight line, being extended by connecting a point p0' and a point p5, the focus of a curve ru in a diametric direction along an outer reflection surface Ru is located at the point p0', one end point p3 of the curve ru is at the light source side from the straight line which is extended by connecting the points p0' and p5 and is located outside the curve rl, and the other end point p4 of the curve ru is the intersection point between the segment lp and the curve ru. |
