There are lot, depending on your requirements. Anyway you can try: ZqQ*}l5
2ev*CX6.
1, Refractive: an achromatic as positive + plano-convex as negative; */w7?QOv
OR edijfhn
2, Reflective: two parabolic mirrors; r?p[3JJ;mG
l$a?A[M$
Both of them affer nice spherical aberration performance. D9BQID$R
zBY~lNB
Reminder: compute the laser beam density, ensure you have enough strong optical coating. fN)x#?
v^SsoX>WMH
Good luck.