laser ranging radar
Laser ranging radar determines the distance between the measured object and the test point by emitting a laser beam to the measured object, receiving the reflected wave of the laser beam, and recording the time difference. Traditionally, lidar can be used in the field of industrial security detection, such as the laser wall seen in science fiction films. When someone intrudes, the system will immediately respond and issue an early warning. In addition, laser ranging radar is also widely used in the field of space surveying and mapping. However, with the rise of artificial intelligence industry, laser ranging radar has become an indispensable core component in the robot body. With the use of SLAM technology, it can help the robot to locate and navigate in real time and realize autonomous walking. The rplidar series developed by Silan Technology, combined with slamware module, is a typical representative of autonomous positioning and navigation of service robots at present. It can complete laser ranging for tens of thousands of times per second within a ranging radius of 25 meters and achieve millimeter resolution.
laser velocimetry radar
laser velocimetry radar is used to measure the moving speed of an object, and the moving speed of the object can be obtained by laser ranging twice with a specific time interval.
there are two kinds of lidar speed measurement methods. one is based on the principle of lidar distance measurement, that is, the target distance is continuously measured at a certain time interval, and the target speed value can be obtained by dividing the difference between the two target distances by the time interval, and the direction of the speed can be determined according to the positive and negative difference of the distance. This method has simple system structure and limited measurement accuracy, and can only be used for hard targets with strong laser reflection.
another kind of speed measurement method is to use Doppler frequency shift. Doppler frequency shift means that when there is a relative velocity between the target and the lidar, there will be a frequency difference between the frequency of the received echo signal and the frequency of the transmitted signal, which is called Doppler frequency shift.
laser imaging radar
laser imaging radar can be used to detect and track targets, and obtain information of target orientation and speed. It can accomplish tasks that ordinary radar can't, such as detecting submarines, mines, hidden military targets and so on. It is widely used in military, aerospace, industrial and medical fields.
atmospheric detection lidar
atmospheric detection lidar is mainly used to detect molecules, smoke density, temperature, wind speed, wind direction and the concentration of water vapor in the atmosphere, so as to achieve the purpose of monitoring the atmospheric environment and forecasting disastrous weather such as storms and sandstorms.
Tracking radar
Tracking radar can continuously track a target, measure the coordinates of the target, and provide the moving track of the target. It is not only used in artillery control, missile guidance, exterior ballistic measurement, satellite tracking, penetration technology research, etc., but also in meteorology, transportation, scientific research and other fields.
Classification by working medium:
Solid-state laser radar
Solid-state laser radar has high peak power, and its output wavelength range matches the existing optical components and devices (such as modulators, isolators and detectors) and atmospheric transmission characteristics, and it is easy to realize the structure of master oscillator-power amplifier (MOPA), plus high efficiency, small size, light weight and high reliability. In recent years, the development of lidar is focused on diode-pumped solid-state lidar.
gas lidar
gas lidar is represented by CO2 lidar, which works in infrared band, with small atmospheric transmission attenuation and long detection distance, and has played a great role in atmospheric wind field and environmental monitoring. However, it is bulky, and the medium-infrared HgCdTe detector used must work at 77K, which limits the development of gas lidar.
semiconductor laser radar
semiconductor laser radar can work continuously with high repetition rate, and has the advantages of long life, small size, low cost and little harm to human eyes. It is widely used in Mie scattering measurement with strong backscattered signals, such as detecting the height of cloud bottom. The potential application of semiconductor lidar is to measure visibility, obtain aerosol extinction profile in atmospheric boundary layer and identify rain and snow, which is easy to be made into airborne equipment.