Sgt. Salis of the Natick Police Department brought our Fitchburg State University Police Program's Recruit Officer Course (ROC) recruits out to the McKay School parking lot for a hands-on lesson in the use of lidar speed tracking. Lidar, which stands for Light Detection and Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth.