| 摘要 |
PROBLEM TO BE SOLVED: To cause light to enter a portion of a lens having a curved surface having an apex where lubricant liquid is attached and collecting the light at the other end, and suppress a variation in collection of light compared with a lens without grooves formed on a curved surface.SOLUTION: A lens 54 includes a curved surface 54A having an apex TS1 on one end, the curved surface 54A having grooves D formed thereon, and collects light LB entering the curved surface 54A at the other end 54B.SELECTED DRAWING: Figure 4 |
