There are lot, depending on your requirements. Anyway you can try: [SKN}:D
Jn :h;|9w
1, Refractive: an achromatic as positive + plano-convex as negative; 7.mYzl-F(
OR MpNgp)%>
2, Reflective: two parabolic mirrors; 2gasH11M
@PL.7FM<v
Both of them affer nice spherical aberration performance. `erKHZ]S
+nAbcBJAl
Reminder: compute the laser beam density, ensure you have enough strong optical coating. SH1S_EQ<
qr@<'wp/
Good luck.