There are lot, depending on your requirements. Anyway you can try: 9lqH
ur\<NApT;
1, Refractive: an achromatic as positive + plano-convex as negative;
z>lIZ}
OR l]R=I2t
2, Reflective: two parabolic mirrors; [] cF*en
v9*31Jx
Both of them affer nice spherical aberration performance. ?*LVn~y
[8jIu&tJf
Reminder: compute the laser beam density, ensure you have enough strong optical coating. 4Dy|YH$>S
#K&XY6cTj
Good luck.