We must not succumb to the image of the "Star Trek" type phaser beam....they all disperse with the square of the distance away. As the knowledgeable poster on Page one said....the best l@sers shot at the moon are 5 times the moon's diameter when they arrive there. If you were to look at the Earth from the moon (directly into the beam) you would most certainly NOT notice it.....it is that diverged.
Actually, the laser NASA used to bounce off the moon was about 7km diameter by the time it reached the moon, not 5 times the moon's diameter!
J