There are lot, depending on your requirements. Anyway you can try: C1T_9}L-A
HaA1z}?n
1, Refractive: an achromatic as positive + plano-convex as negative; R];Oxe
OR 1e xl0]-
2, Reflective: two parabolic mirrors; !?
^h;)a
<"o"z2
Both of them affer nice spherical aberration performance. $-+/$!
0=w K:Ex
Reminder: compute the laser beam density, ensure you have enough strong optical coating. RkFD*E$
&iN--~}!$
Good luck.