Lidar Range Finders

A laser rangefinder is a rangefinder that uses a laser beam to determine the distance to an object. The most common form of laser rangefinder operates on the time of flight principle by sending a laser pulse in a narrow beam towards the object and measuring the time taken by the pulse to be reflected off the target and returned to the sender. 

The term LIDAR originated as a portmanteau of "light" and "radar". Lidar uses ultraviolet, visible or near infrared light to image objects.