There are two very distinct classes of l@zers that might be used by
astronomers.
The first is a classroom l@zer pointer used to highlight sights in the
sky for a huddle of people at night, see
5mW Green Laser Pointer for Astronomy.
There's no reason for these to exceed 5mW.
The second is the multi-10W class of yellow l@zers used to produce a
~90-km-high sodium beacon to sample atmospheric turbulence above
a small number of professional observatories. These are always used
with spotters, who cut off the l@zer on sight of aircraft. See,
http://www2.keck.hawaii.edu/optics/l...cs/kaon361.pdf.
These are launched through 20-cm-class telescopes, so they have
finite width, but would definitely hurt. In the US, pointing directions
must also be approved in advance by the USAF to avoid satellite
collisions, and on a typical night there are a handful of windows where
the air force refuses the observatory permission to use the l@ser.
I would be interested to know whether pilots operating near Mounts
Hamilton and Palomar, California and Mauna Kea in Hawaii have noticed
these yellow/orange beams, especially on night-vision goggles. It is very likely that military observatories in Hawaii and the western US use similar
beacons.
These l@zer classes are so distinct in properties, that neither should
interfere with aircraft operations. The first by being no risk, and the second by being turned off if aircraft are near. I am sceptical that an innocent astronomy spotting pointer being scanned from star to star in the sky could be responsible for an aircraft blinding incident, and would expect a court
to see through this as a defense, especially as there's no reason to use
a pointer without a small crowd of witnesses.
I would expect that atmospheric chemistry sounding l@zers and l@zer-show
l@zers would pose more of a risk.