Earth's atmosphere is a constant annoyance for anyone trying to do anything useful with light. Even if you discount things like clouds, smog, and smoke, there are layers and pockets of air of varying temperatures that routinely make things go all wobbly. This is why most halfway decent telescopes are built on the tops of mountains and all the best telescopes are out in space.
Things get even more difficult when you're trying to push a lot of light through the atmosphere with the goal of having it all end up exactly where you want it, as is the case with a directed energy weapon. Adaptive optics have been able to help somewhat, but wouldn't it be better if the atmosphere could actually do something useful? You know, for once?
BAE Systems has been working on a way to use lasers to actively reshape the atmosphere to turn it into a variety of optical tools. The Laser Developed Atmospheric Lens system (LDAL) uses powerful laser pulses to make air itself into lenses, mirrors, and even protective deflector shields.