| 摘要 |
PROBLEM TO BE SOLVED: To provide a fly eye lens capable of showing desired optical performance even if thermal expansion occurs by providing positioning parts along reference lines passing a thermal expansion center, in the periphery. SOLUTION: This fly eye lens 10 including plural cells in an optical function part 20 has a first positioning part 40, a second positioning part 50 and a third positioning part 60 in the periphery. The first positioning part 40 and the second positioning part 50 are formed on one side of an area divided by a first reference line X passing a thermal expansion center O of the lens 10. Respective end parts of the first positioning part 40 and the second positioning part 50 are positioned on the first reference line X, while an end part of the third positioning part 60 is positioned on a second reference line Y perpendicular to the first reference line X, passing the thermal expansion center O of the lens 10. Thereby, the position of the thermal expansion center O of the fly eye lens 10 becomes constant in an optical system even if thermal expansion occurs, to keep desired optical performance. |
