Until we figure out how to make a phaser that can be set to stun, we've been stuck with
non less-lethal options like tasers (which can kill) and laser dazzlers (which can cause eye damage). StunRay is basically just a big flashlight, except with the ability to disable you by causing "inverse blindness."
If you're wondering what inverse blindness looks like, it's easy to do to yourself: just stare at a bright light for a minute or two and then look around. It's not dark, really, but you can't see anything very well, and it's because the exposure to bright light has overloaded the neurons that connect your retinas to your brain, and mostly all you can see is a featureless white expanse. The technical term for this is "loss of contrast sensitivity," and it's an effective way of disabling someone.
A company called Genesis Illumination is working what's basically a giant fancy flashlight called StunRay that can inflict this loss of contrast sensitivity or inverse blindness or neural overload or whatever you want to call it on people at long range in a split second. Each burst of super bright light incapacitates subjects for five seconds or so without causing any pain, and subjects fully recover in about five minutes. The "fully recover" bit is key, since StunRay won't roast your eyeballs like a laser dazzler can.
StunRay uses a 75 watt bulb, which doesn't seem like much, but with some fancy optics, the device is able to focus its light beam to be ten times brighter than an aircraft landing light, even up to 150 feet away. And in case you were wondering, and I'm sure you were, this is bright enough to read a newspaper from a mile away.
Genesis Illumination just received a patent for StunRay, so in the near future, we'll be able to rely on one single device for both our disabling and long distance newspaper-reading needs.