Unfortunately, even laser light has too much divergence (due to intrinsic behaviour of waves) to remain one focused tight spot by the time it reaches Proxima Ce

Unfortunately, even laser light has too much divergence (due to intrinsic behaviour of waves) to remain one focused tight spot by the time it reaches Proxima Centauri, or even the outskirts of our solar system. https://en.wikipedia.org/wiki/Laser#The_light_emitted https://en.wikipedia.org/wiki/Laser#The_light_emitted does say that the rate of divergence is inversely proportional to the diameter of the beam, so maybe if we make the beam really wide, it could reach Proxima Centauri without spreading too much.. I don't know how wide that would have to be.