What is a lidar system?

A radar that uses a laser as a radiation source. Lidar is a combination of laser technology and radar technology. It consists of transmitter, antenna, receiver, tracking frame and information processing. Emitters are various types of lasers, such as carbon dioxide lasers, Nd-doped yttrium aluminum garnet lasers, semiconductor lasers and solid-state lasers with adjustable wavelengths. The antenna is an optical telescope; The receiver adopts various forms of photodetectors, such as photomultiplier tubes, semiconductor photodiodes, avalanche photodiodes, infrared and visible light multi-detector devices, etc. Lidar works in two modes: pulse or continuous wave. Detection methods are divided into direct detection and heterodyne detection.

From the first photo taken by Daguerre and Nipce in 1839, the technology of making photo plane (x, y) by using photos has been used to this day. 190 1 year, the Dutch Fourcade invented the stereo observation technology of photogrammetry, which made it possible to obtain three-dimensional data (x, y, z) of the ground from two-dimensional photos. In the past 100 years, stereo photogrammetry is still the most accurate and reliable technology to obtain three-dimensional data on the ground, and it is also an important technology for national basic scale topographic mapping.