There are lot, depending on your requirements. Anyway you can try: ZGrV? @o,6
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1, Refractive: an achromatic as positive + plano-convex as negative; emHi=[!i
OR
A=,m
2, Reflective: two parabolic mirrors; ^O?$}sr
V6!oe^a7'
Both of them affer nice spherical aberration performance. !xlVyt5e
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Reminder: compute the laser beam density, ensure you have enough strong optical coating. C/E3NL8
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Good luck.