There are lot, depending on your requirements. Anyway you can try: P+Gz'
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1, Refractive: an achromatic as positive + plano-convex as negative; *fs[]q'Q
OR !x:{"
2, Reflective: two parabolic mirrors; ~
MsHV%
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Both of them affer nice spherical aberration performance. ($!uBF-b
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Reminder: compute the laser beam density, ensure you have enough strong optical coating. (?g+.]Dt,
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Good luck.