how to deliver and focus

I have to deliver a CO2 laser beam (100W, 4mm diameter, 4mrad
full-angle divergence) on two targets getting the same spot size. The
fisrt target is located 1 meter far from the source, while the second
is 20m away! On each target I have a single lense for focusing the
beam. In between there are also other target, but what count here are
the the first one and the last one. I supposed to place a 5x beam
expander just after the source to enlarge (better for focusing) the
beam size and to have a lower divergence, but 0.08mrad of divergence
still force me to have a too big beam size on the 20m target, even
bigger than my focusing ZnSe lense. I was thinking to displace to each
other the 2 lenses of the beam expander, in order to have a behaviour
like a low positive lement instead of an afocal element, to compensate
the divergence with this pre-focusing. My question is, are there other
better solutions? Doing this way could I reach a good spot size, i.e.
lower that 200um?
All your help is really welcome!
Thanks, Marco

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