There are lot, depending on your requirements. Anyway you can try: `VFl|o#H
:ZfUjqRE
1, Refractive: an achromatic as positive + plano-convex as negative; TJ[jZuT:
OR Mto~ /
2, Reflective: two parabolic mirrors; E9d i
CotMV^
Both of them affer nice spherical aberration performance. @*"<U]
y]YS2^
Reminder: compute the laser beam density, ensure you have enough strong optical coating. ;]ShC\1
:z} _y&]
Good luck.