The Author(s) 2016. In this contribution we discuss the use of optics in remote sensing. The first remote sensing applications were passive in nature, i.e., used the light reflected or scattered from objects, etc. With the advent of the laser a perfect light source for active remote sensing became available; specifically, the light output of a laser has a high intensity in a well-collimated beam that can be propagated over large distances. After a brief review of the technical progress necessary to the development of the laser, we specifically discuss Lidar (light detection and ranging) and its applications to remote sensing in the atmosphere and oceanic research. Finally, we briefly discuss newer developments in remote sensing with ultra-short pulses.