There are lot, depending on your requirements. Anyway you can try: s/UIo^m
-fuSCj
1, Refractive: an achromatic as positive + plano-convex as negative; 5i7,s
OR 6Lz{/l8
2, Reflective: two parabolic mirrors; `o
yz"07m
n|IdEgD$
Both of them affer nice spherical aberration performance. OEy'8O$
RVy8%[Gcq
Reminder: compute the laser beam density, ensure you have enough strong optical coating. AZz
}
g4!zH};n
Good luck.