| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical lens having a diaphragm function capable of eliminating light beams in the outside of an optically effective surface without impairing an optical performance. SOLUTION: In this optical lens 24 consisting of a transparent material, the light source side surface 24a is formed into a projected aspheric surface of rotational symmetry defined by a function with respect to a distance (radius) from an optical axis, and the aspheric surface is provided with a slight difference 24c in level at the prescribed radial position and also is provided with a place where the differential coefficient of the above described function is discontinuous at the prescribed radial position. The above described slight difference in level is specified to 0.01 mm or less. |
