There are lot, depending on your requirements. Anyway you can try: wn*<.s
U 7mA~t2E
1, Refractive: an achromatic as positive + plano-convex as negative; =
7U^pT
OR }#~@HM>6Z
2, Reflective: two parabolic mirrors; 6<0-GD}M
9_Tk8L#
Both of them affer nice spherical aberration performance. 9>~UqP9
g7*c wu
Reminder: compute the laser beam density, ensure you have enough strong optical coating. v_Om3i9$E
lK;/97Ze
Good luck.