1/r^2 comes from the fact that space is three dimensional. No amount of beam collimating can change that (unless we have some fundamental breakthrough/change in

1/r^2 comes from the fact that space is three dimensional. No amount of beam collimating can change that (unless we have some fundamental breakthrough/change in our understanding of physics). Better beam coherence could keep improving on the solid angle, which is the multiplicative coefficient to the (asymptotic) scaling behavior.