There are lot, depending on your requirements. Anyway you can try: yY UAH-
]$s)6)kW
1, Refractive: an achromatic as positive + plano-convex as negative; Sft
vN-
OR Jf7H;ZM<
2, Reflective: two parabolic mirrors; |iBf6smF
L7rr/D
Both of them affer nice spherical aberration performance. dba_(I~y
ATc!c +
Reminder: compute the laser beam density, ensure you have enough strong optical coating. x<!]#**;
!*&5O~dfN
Good luck.