There are lot, depending on your requirements. Anyway you can try: bVEt?E*+
y6.Q\=
1, Refractive: an achromatic as positive + plano-convex as negative; K!|%mI8gk
OR Ok7i^-85
2, Reflective: two parabolic mirrors; >Ux5UD
}]0f -}
Both of them affer nice spherical aberration performance. yDwG,)m 4s
vA(V.s`
Reminder: compute the laser beam density, ensure you have enough strong optical coating. O gQE1{C
bERYC|
Good luck.