There are lot, depending on your requirements. Anyway you can try: `]65&hWZL
Y[e.1\d'
1, Refractive: an achromatic as positive + plano-convex as negative; @{b5x>KX
OR (87wWhH
2, Reflective: two parabolic mirrors; f&$Bjq
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Both of them affer nice spherical aberration performance. GDCp@%xW
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Reminder: compute the laser beam density, ensure you have enough strong optical coating. q5r7KYH{
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Good luck.