They're used to it
They've been using lasers from the observatories in the canaries for some time now,
such as from the Isaac Newton telescope there:
The lasers are used to create an "artificial star" in the field of view of the telescope by fluorescing sodium atoms in the upper atmosphere (you need a bright star in the image to align the optics with).
Newer telescope plans have lots of laser stars (10-20) and beams, e.g. for the EELT (42m) telescope that ESO is building.