Would a laser dazzler be militarily useful? I saw Why don&#39;t combat aircraft have rear-facing *laser* weapons? pop up in the Hot Questions list and that motivated me to join here and ask this question. 

Weapons that blind are banned. But what if they merely dazzle?

I'm imagining a little box with a laser pen in it - like those that so trouble landing pilots when wielded by foolish people on the ground. The box can point the laser around the sky and switch it on or off. It's a relatively cheap unit. It's probably controlled from an air defence computer that is looking at radar, IFF etc, that tells it where to point. If a hostile aircraft arrives, dazzle it.

Of course, the first thing the hostile aircraft will do is shoot up the box. (So you wouldn't want to be a human defender pointing a laser pen.) But if the boxes are cheap enough, you could scatter a hundred or so around any base you were trying to defend, and target an attacker with just one box at a time. When it gets blown up, use another box.

Without fancy radar, IFF etc (you may have no aircraft so you want to dazzle all of them) you could put a camera and image recogniser in each box.

If it all goes wrong and points at a friendly aircraft or even a human on the ground, probably no harm will come. But it seems it would make it much harder for an aircraft flown by a human to attack a target. It could work against drones, too, even relatively high-flying ones.

Would it work?

Would such a system be legal? Practical? Has anyone deployed one? Is anyone working on one?
Such a system already exists (in a way) and is in place to warn pilots who improperly enter the DC SFRA area. Im not sure it "dazzles" but it is what you describe and could be extended to do so. You can see an example of it running here.