What is laser radar? Introduction to laser radar

In the application of autonomous driving, LiDAR is mainly used to detect obstacles on the road, transmit data and signals to the brain of autonomous driving, and then make corresponding driving actions. However, common outdoor interference factors such as rain, fog, snow, dust, high and low temperatures have a great impact on the recognition of LiDAR. Therefore, before LiDAR is put into practical application, a large number of tests need to be carried out in special environments such as rain, fog, light, and dust.

Under natural environmental conditions, the required test scenarios are hard to come by and cannot be reproduced, which cannot meet the needs of large-scale real-environment testing of lidar.

LiDAR is a sensor that is currently changing the world. It is widely used in self-driving cars, drones, autonomous robots, satellites, rockets, etc. The laser measures the propagation distance (Time of Flight, TOF) between the sensor transmitter and the target object, analyzes the reflected energy size, amplitude, frequency and phase of the reflected spectrum on the surface of the target object, and outputs a point cloud, thereby presenting the precise three-dimensional structural information of the target object.

LiDAR is composed of a laser transmitting unit and a laser receiving unit. The transmitting unit works by emitting layers of laser beams. The more layers there are, the higher the accuracy is, but this also means that the sensor size is larger. After the transmitting unit emits the laser, when the laser encounters an obstacle, it will be reflected and then received by the receiver. The receiver creates a set of point clouds based on the time when each laser beam is emitted and returned. A high-quality LiDAR can emit more than 200 laser beams per second.

As for the wavelength of laser, currently, laser transmitters with wavelengths of 905nm and 1550nm are mainly used. Light with a wavelength of 1550nm is not easy to transmit in the liquid of the human eye. Therefore, 1550nm can greatly increase the transmission power while ensuring safety. High power can achieve a longer detection distance, and long wavelength can also improve anti-interference ability. However, 1550nm lasers require the use of InGaAs, which is currently difficult to mass produce. Therefore, Si materials are currently used more to mass produce 905nm LiDAR. Safety is ensured by limiting power and pulse time.