It is quite easy to believe that as-lased from lasers in the lidar units, the beams are generally safe.
But could other optical mechanisms such as eye-glasses accidentally focus these dispersed beams in such a way that they could again be dangerous?
But if eye-glasses could do that, then people would get retinal burns from the sun, and so on. Remember that all glasses do is adjust the path of light reaching the lens of the eye so that when it arrives at the retina it is identical to the path of light focussed by a normal, healthy eye. Which also means that another way we know it isn't a problem is that people without glasses are safe.
Also, remember that this is medium-wavelength IR at 1500nm, which is between two and three times the wavelength of visible at 400-700nm approximately. The energy in a photon is calculated as E = hf = hc/l where h is Planck's constant and c is the speed of light, while l is the wavelength. Notice how the energy decreases nice and linearly as the wavelength increases - this is good!