There are lot, depending on your requirements. Anyway you can try: pr4y*!|Y$
L>E{~yh
1, Refractive: an achromatic as positive + plano-convex as negative; b2[U3)|oO
OR vSoG] :1
2, Reflective: two parabolic mirrors; (f_J @n
vUO[V$rx
Both of them affer nice spherical aberration performance. Z,O-P9jC
/0|1xHs
Reminder: compute the laser beam density, ensure you have enough strong optical coating. Le bc@,
GVn'p
Wg
Good luck.