There are lot, depending on your requirements. Anyway you can try: \qTp#sF
#R7hk5/8n}
1, Refractive: an achromatic as positive + plano-convex as negative; ^/cqE[V~,
OR s IBP$9
2, Reflective: two parabolic mirrors; a^\F9^j
[mj=m?j
Both of them affer nice spherical aberration performance. 2jlz#Sk
H0jbG;
Reminder: compute the laser beam density, ensure you have enough strong optical coating. Sy]W4%
"a(e2H2&T4
Good luck.