MeekandMild,
Good point. I think the water vapor in the denser lower atmosphere helps attenuate specular reflections at long slant distances, so the main eye danger would be to troops in-theater (who would probably be issued with infrared-opaque glasses). One reason they're going through all the trouble to stick the Airborne Laser on a 747 is to get the beam source up into the stratosphere where water vapor attenuation is less of a problem, allowing the laser to shoot things down hundreds of miles away. Since THEL is more of a point-defense-type system, propagation range is less of an issue.