There are lot, depending on your requirements. Anyway you can try: Sm)Ha:[4
mtJ9nC
1, Refractive: an achromatic as positive + plano-convex as negative; C9~52+S
OR Ir
{OheJ
2, Reflective: two parabolic mirrors; \DYWy*pe
?j40}
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Both of them affer nice spherical aberration performance. T^Y([23
ABQa 3{v
Reminder: compute the laser beam density, ensure you have enough strong optical coating. GR
+[UG
isQ[ Gc!8
Good luck.