There are lot, depending on your requirements. Anyway you can try: --5F*a{R|
q(KjhM
1, Refractive: an achromatic as positive + plano-convex as negative; 6mM9p)"$
OR Rf:.'/<^
2, Reflective: two parabolic mirrors; aFnel8
t3;Zx+Br
Both of them affer nice spherical aberration performance.
I1Q!3P
]\(8d[4
Reminder: compute the laser beam density, ensure you have enough strong optical coating. KdVKvs[
![_x/F9
Good luck.