There are lot, depending on your requirements. Anyway you can try: BavO\{J#|0
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1, Refractive: an achromatic as positive + plano-convex as negative; `\Unpp\I
OR W WG /k17
2, Reflective: two parabolic mirrors; T-" I9kM
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Both of them affer nice spherical aberration performance. 1|QvN1?
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Reminder: compute the laser beam density, ensure you have enough strong optical coating. =Agg_h
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Good luck.