There are lot, depending on your requirements. Anyway you can try: y(Pv1=e
\>/AF<2"
1, Refractive: an achromatic as positive + plano-convex as negative; A[88IMZs
OR ,E(M<n|.
2, Reflective: two parabolic mirrors; &6Wim<*
CwEb ?
Both of them affer nice spherical aberration performance. F>u/Lh!
H/#WpRg
Reminder: compute the laser beam density, ensure you have enough strong optical coating. ^> d"D
0"@p|nAa
Good luck.