The principle of LiDAR is similar to Electronic Distance Measuring Instrument (EDMI), where a laser (pulse or continuous wave) is fired from a transmitter and the reflected energy is captured (Figure 2). Using the time of travel (ToT) of this laser the distance between the transmitter and reflector is determined. The reflector could be natural objects or an artificial reflector like prism. In case of ranging LiDAR this distance is one of the primary measurement which with integration with other measurements also provides the coordinates of the reflector. This is shown in the following paragraphs.
Figure 2 Principle of range measurement using laser