There are lot, depending on your requirements. Anyway you can try: fW/G_
u\L=nCtLby
1, Refractive: an achromatic as positive + plano-convex as negative; N)F&c!anh
OR pKSn
3-A
2, Reflective: two parabolic mirrors; ,tt
.oF|
|I; tBqN{u
Both of them affer nice spherical aberration performance. G9`;Z^<L
hLs<g!*O
Reminder: compute the laser beam density, ensure you have enough strong optical coating. j`fQN
D'{NEk@
Good luck.