There are lot, depending on your requirements. Anyway you can try: sO~:e?F
66x>*
1, Refractive: an achromatic as positive + plano-convex as negative; >|L,9lR_b
OR AvdxDN
2, Reflective: two parabolic mirrors; %D|27gh
dUOvv/,FZT
Both of them affer nice spherical aberration performance. lBS!=/7
7@u0;5p|
Reminder: compute the laser beam density, ensure you have enough strong optical coating. u+eA>{
$9dm2#0d
Good luck.