There are lot, depending on your requirements. Anyway you can try: AK!hK>u`
/93l74.w
1, Refractive: an achromatic as positive + plano-convex as negative; 3REx45M2
OR g*UMG>
2, Reflective: two parabolic mirrors; !$;a[Te
I04jjr:<
Both of them affer nice spherical aberration performance. RyJ 1mAC
-t2T(ha
Reminder: compute the laser beam density, ensure you have enough strong optical coating.
|{r$jZeE
}R[#?ty;]
Good luck.