OK - I have to weigh in here, and please understand, I mean no offense to ANYONE here (and yes, I know people say that right before they offend, but I'm really going to make an effort here). I work with lasers, I've read the literature, I've written some of the literature - I don't know if I am an expert, but I have been hired as one, and my clients (including several military customers) have been happy with my performance. That's as close as you get to my credentials in this public forum. That said, here are my thoughts, and although some of this repeats information already here, I'll try to be complete:
IF such a device as a laser was going to be used to blind pilots in an aircraft, either permanently or temporarily, it would have to be:
A) Visible (not because the pilots have to see it, but because it has to get through the glass of the cockpit, which filters out both UV and IR)
B) "High power" - not high continuous power, but high pulsed power, and not high compared to those used for boost phase intercept, but high compared to that used for eye surgery or laser pointers. The power would be "high" because the natural reflex of the target would be to close their eyes immediately, so damage would have to be inflicted as rapidly as possible. At sufficiently high levels of power the atmosphere will ionize (this is the kind of power required to perform boost phase intercept on ballistic missiles, for example), but MUCH lower power levels are required to blind humans, and the losses through the atmosphere are much lower at these "lower" power levels. (Was all of that confusing enough??) These lasers are available commercially, and are not cheap, but are certainly within reach of a terrorist organization, or an upper-middle class whacko.
3) Low diffraction, or "spreading" - luckily for the designer of pilot-blinding lasers, this goes with making the beam just a little bit bigger than your standard eye-surgery/laser pointer beam - that is to say, spreading the beam out larger at the point of transmission (together with other appropriate optics choices) helps to reduce the spread of the beam over distance - there's no point in making the beam narrower than you can point it, or than you can hold it on the target during the time of the "attack".
4) Pointed accurately during the "attack" - this can now be accomplished with available optical processors and optics with a minimum amount of programming, together with a beam director appropriate to the laser being used - these are now available for a variety of applications, especially for such a slow-moving and high-stability target as a commercial aircraft - these kind of targets used to be hard to hit, and are still nearly impossible to hit with a "hand-held" device like a laser pointer, no matter what kind of aids might be provided, but current technology provides easily purchased solutions for our pilot-hating whackos.
OK - I've probably missed 40 posts by now, so I'll go ahead and submit this, and stand by for flames. Please also understand that if this is being done in the US, this is a serious and credible threat, and it needs to be taken seriously. These components are available, and can be integrated by an average engineer - many of whom are available for the right price. Scary.