Are there any drawbacks to having intermediate foci in a multi lens optical system? For instance in a dynamic beam expander? I have a five lens system I am designing, but have a focus point between lens four and five when maximizing the beam diameter. There will not be enough power at the focus to ionize the air, so I am not worried about that.

  • Following convention, of course, with the source propagating from left to right with the lenses numbered as such. – michaelkm8 Sep 14 '17 at 15:59

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