There are lot, depending on your requirements. Anyway you can try: ')>D*e
/A93mY[
1, Refractive: an achromatic as positive + plano-convex as negative; 5U6b\jxX
OR k;Ask#rs
2, Reflective: two parabolic mirrors; M?QX'fia
[U_
Both of them affer nice spherical aberration performance. +Sak_*fq
hE;BT>_dn
Reminder: compute the laser beam density, ensure you have enough strong optical coating. w3jcit|
b=XHE1^rM
Good luck.