There are lot, depending on your requirements. Anyway you can try: u2\QhP 9
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1, Refractive: an achromatic as positive + plano-convex as negative; -9)H[}.
OR {Qv Whf
2, Reflective: two parabolic mirrors; v%^"N_]
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Both of them affer nice spherical aberration performance. |YEq<wbQ
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Reminder: compute the laser beam density, ensure you have enough strong optical coating. ^W#161&
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Good luck.