I don't know much about masers but I think power source would be a problem so I'll talk about chemical lasers... (of course I don't know much about them either)<br /><br />Laser beams still spread over the very long distance. I think the beam used in the retroreflector ranging experiments, which they focus as tightly as they can, spreads to something like 5 miles diameter by the time it gets to the moon, with the intensity reducing proportional to 1/(beam diameter)^2<br /><br />Even if you could somehow solve the beam dispersion problem you'd still neat a honkin' big laser. The chemical laser used for ballistic missile defense tests is a one-shot device (without refueling) and takes up a whole 747 so I imagine it weighs something in the range of 50-200 tonnes. That only gets you one shot, and anyway I'm not sure it would be up to melting regolith even apart from the range issue. When used against ballistic missiles, it doesn't vapourise the missile, rather it just heats the surface of the missile booster's propellant tanks enough that they lose a little strength and fail from the internal pressure. I don't think moonrock is that fragile.<br /><br />Even if you could, why bother? Apollo managed to get down fine and the dust was a bit annoying, perhaps slightly hazardous during approach from a visibility point of view but precision guidance should fix that.