| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lens with a diaphragm easily produced and capable of decreasing the influence of undesired returning light by providing diaphragm structure at the outer edge part of a lens on a light entering side and constituting the diaphragm structure so that one part of entering parallel beams may be reflected and the reflected light may turn in a direction where it is separated from the optical axis of the parallel beams. SOLUTION: This lens 1 is equipped with a light entering lens part 2, a light emitting lens part 3 and an annular flange part 4 provided at the outer edge part formed by the parts 2 and 3. Then, the flange part 4 is provided with a light entering surface (diaphragm structure) 4a arranged on the lens part 2 side and a light emitting surface 4b arranged on the lens part 3 side, and the surface 4a is a circular-arc surface in circular-arc shape swollen to the outside with respect to the optical axis of the lens 1, and the surface 4b is a plane orthogonal to the optical axis of the lens 1. The surface 4a is constituted of a plane optically designed so that the incident parallel beams may be reflected in the direction where they may separated from their optical axis and has both a function to converge the parallel beams and a function to prevent the parallel beams from being undesirably reflected to an incident side. |
