There are lot, depending on your requirements. Anyway you can try: N\|B06X
IO7z}![V;
1, Refractive: an achromatic as positive + plano-convex as negative; ;apLMMsWC
OR .J.}}"+U
2, Reflective: two parabolic mirrors; gd[muR ~
S1k*"><
Both of them affer nice spherical aberration performance. *gmc6xY
<v ub
Q4
Reminder: compute the laser beam density, ensure you have enough strong optical coating. [,bJKz)a
s-#@t
Good luck.