There are lot, depending on your requirements. Anyway you can try: TJZar Nc$
b7gN|Hw5 H
1, Refractive: an achromatic as positive + plano-convex as negative; TpdYU*z_Br
OR Kb'4W-&u!
2, Reflective: two parabolic mirrors; S9'Xsh
Mf7
[@#$
Both of them affer nice spherical aberration performance. @twi<U_
u('`.dwkc
Reminder: compute the laser beam density, ensure you have enough strong optical coating. _3#_6>=M
bik lja
Good luck.