[knotimpressed]

I wonder if the requirement to rotate the target is inherent, or if it could be optimized away eventually?

[stevemadere]

I suspect this was an easy way to test it without having to build a rotatable optical bench.

A practical device may be an array of light sources and telescopes on a rotating mount or a set of moveable mirrors that achieve the same effect.

[nkrisc]

If it is required, then in a real application you could just rotate the laser array instead.

[Noumenon72]

I also wonder about the requirement for the letters to be made of reflective material.

[xnx]

Or rotate the telescopes

[IAmBroom]

... which are radially symmetric.