There are lot, depending on your requirements. Anyway you can try: 8Vn4.R[vE
(S/F)?
1, Refractive: an achromatic as positive + plano-convex as negative; c0rk<V%5+
OR |J>WC}g@n
2, Reflective: two parabolic mirrors; 0XU}B\'<
L%h/OD
Both of them affer nice spherical aberration performance. i.y)mcB4
Q8nId<\(
Reminder: compute the laser beam density, ensure you have enough strong optical coating. <02m%rhuW
K5 KyG
Good luck.