There are lot, depending on your requirements. Anyway you can try: G
m40u/
uCuXY#R+
1, Refractive: an achromatic as positive + plano-convex as negative; !~PLW] Z4
OR i3g;B?54
2, Reflective: two parabolic mirrors; $[txZN
f@lRa>Z(Fm
Both of them affer nice spherical aberration performance. %cJ]Ds%V
+Z[(s!
Reminder: compute the laser beam density, ensure you have enough strong optical coating. #]bWE$sU<
$$8xdv#
Good luck.