Since the laser was invented in the 1960s, lidar has developed on a large scale. Laser has become a real driver, making lidar cheap and reliable, making it more competitive than other sensor technologies. Laser radars begin to work in the visible region (ruby laser), then in the near infrared region (Nd: YAG laser), and finally in the infrared region (CO2 laser). At present, many lidars work in the near infrared region (1.5 um) which is harmless to human eyes. Based on the principle of lidar, many new technologies, such as OCT and digital holography, have been paid more and more attention.
The application of lidar in surveying and mapping mainly includes ranging, positioning and drawing of the earth and foreign objects; coherent lidar has important applications in environmental applications, such as wind sensing and the development of synthetic aperture lidar; gated imaging is mainly used in military, medical and security aspects; and lidar has been applied in vascular research and eye vision correction. Ghost lidar has been applied in theory and Simulation in the form of new technology. As an important technology, lidar is used by autopilot and UAV. It is also used by police to measure speed, as well as games such as Microsoft‘s Kinect sense game.
Throughout the development history of lidar in Europe, the United States, the former Soviet Union, Japan and China, lidar has gone through many stages of development. From the earliest laser ranging, lidar has been widely used in military ranging and weapon guidance, especially in laser positioning (bistatic radar). Further research has led to the development of laser imaging system based on two-dimensional gating monitoring and three-dimensional imaging technology in the process of equipment. The development of imaging system mainly includes: wider range and cross-range resolution, single photon sensitive array, multi-frequency or wide-spectrum laser emission with multiple functions, better penetration ability, traversing plants, traversing dense media for target recognition and other applications.
In civil and military-civilian applications, environmental lidar technology has matured in the field of atmospheric and ocean remote sensing research, while in many countries, three-dimensional mapping lidar has entered the operational state. With the increasing efficiency of laser, and more compact and cheaper, it provides potential applications for automobiles and UAVs. The application of autopilot vehicle is probably the most widely used commercial application of lidar, which greatly reduces the size, weight and cost of lidar.
Lidar technology has many applications in medicine, one of which is optical low coherence tomography. This technology originates from the wide application of laser reflector in ophthalmology to study the three-dimensional reconstruction of eye structure. It realizes the three-dimensional endoscopy of blood vessels and extends to Doppler three-dimensional velocimeter. Another important example is refractive imaging of human eye diopter. Research.
In the research of lidar system, many new technologies and methods have emerged, including porous and synthetic aperture, bidirectional operation, multi-wavelength or broadband emission laser, photon counting and advanced quantum technology, combined passive and active systems, combined microwave and lidar, etc. At the same time, it is expected that coherent lidar will be used to increase the method of obtaining full-field data. In terms of components, effective multi-functional laser sources, compact solid-state laser scanners, non-mechanical beam control and shaping, sensitive and larger focal plane arrays, effective hardware and algorithms for processing lidar information and high data rate are used to achieve direct and coherent detection.
By comparing the achievements of lidar technology in the past 50 years in various countries, the results show that lidar technology and related applications still have a broad application prospect.