What is LiDAR and How Does it Work?

10 Nov.,2022


Aerial Remote Sensing

A LiDAR system may use a scan mirror, multiple laser beams, or other means to "scan" the object space. With the ability to provide accurate measurement of distances, LiDAR can be used to solve many different problems.

In remote sensing, LiDAR systems are used to measure scatter, absorption, or re-emission from particles or molecules in the atmosphere. For these purposes, the systems may have specific requirements on the wavelength of the laser beams.  The concentration of a specific molecular species in the atmosphere, e.g. methane and the aerosol loading, can be measured. Rain droplets in the atmosphere can be measured to estimate the distance of a storm and the rain fall rate.

Other LiDAR systems provide profiles of three-dimensional surfaces in the object space. In these systems, the probing laser beams are not tied to specific spectral features. Instead, the wavelength of the laser beams may be chosen to ensure eye safety or to avoid atmospheric spectral features. The probing beam encounters and is reflected by a "hard target" back to the LiDAR receiver.

LiDAR can also be used to determine the velocity of a target. This can be done either through the Doppler technique or measuring the distance to a target in rapid succession. For example, atmospheric wind velocity and the velocity of an automobile can be measured by a LiDAR system.

In addition, LiDAR systems can be used to create a three-dimensional model of a dynamic scene, such as what may be encountered by an autonomous driving vehicle. This can be done in various ways, usually using a scanning technique.