Sometimes you have to process crime or fire scenes in the wind, dust, rain and snow. Leica ScanStations are professional grade quality and are built to handle the elements. They are used all over the world for the most demanding construction projects in all kinds of conditions.
ScanStations have what is known as an IP rating (of 54). This is an internationally used measure of how well an instrument can handle dust and moisture. Because ScanStations have completely enclosed mirrors and optics (as opposed to exposed) it is designed to withstand real world conditions without damage to the scanner. If the scanner you are considering doesn’t have an IP rating, you had better ask about if they recommend using it in the rain.