Looking for help with lens arrangement

Hi,

I'm working on a project that involves projecting a series of 10 laser
beams (actually the same beam being manipulated with a galvanometer
mirror and blanking control) at a target and counting the number of
beams that get returned.

The beams are arranged in a straight line of 10 points. Let's say 5
strike the object and are reflected back, so 5 pulses are recorded by
a photodiode.

My problem is I want to use one photodiode with a total active area of
about 3mmx3mm. I therefore need to focus the image of my returned 10
beams down to this size.

I've already focused them down to 10 points with a single convex lens,
and placed a diode at each point - but I would really like to only use
a single diode if I can.

I'm looking for some background help on choosing and placing lenses to
bring the image down to the 3x3mm size.

Any help would be appreciated.

Thanks,
Dave

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