There are lot, depending on your requirements. Anyway you can try: E
uk[ @1
9Jf.Ls
1, Refractive: an achromatic as positive + plano-convex as negative; f9b[0L
OR Z<[f81hE&
2, Reflective: two parabolic mirrors; rqi|8gKY
inv 5>OeG
Both of them affer nice spherical aberration performance. vA@\V)s
?C|b>wM/
Reminder: compute the laser beam density, ensure you have enough strong optical coating. rY(h }z
H=>;Mj
Good luck.