Velodyne Laser Teardown 

+Mark Philpott Couldnt have said better myself. Good job.

Lidar relies on accurate reflection. So it's not great at long distances as refraction due to changes in air temperature start to effect it. But to a few hundred meters it can be very accurate. I don't know about this system, but cm and mm resolutions are possible with total stations using a similar tech. Using retroreflectors can increase that to a couple of km. But not quickly as pointing a laser at a specific location km away accurately is not easy.