| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens easily attached, aligned in a rotating direction with the large degree of freedom and further obtaining high-uniformity characteristic. SOLUTION: A flange 3 is formed on the outer periphery of a lens part 2, and a notched part 4 notched in a chord direction and obtained by notching one part in the thickness direction of the flange 3 is formed at one part of the outer periphery of the flange 3. |
