I. What is LiDAR?
Car companies are all emphasizing LiDAR, so first we need to understand what LiDAR is.
(LiDAR)
LiDAR—often called the "eyes of robots"—is an important sensor that integrates laser, GPS, and inertial measurement units. It measures distance by emitting laser light and detecting the time it takes for the light to return. The principle is similar to radar, but laser light is used instead of radio waves. LiDAR is arguably one of the key hardware components that helps cars achieve advanced driver assistance features.
II. What is the working principle of lidar?
Next, let's talk about the working principle of lidar.
First, it's important to clarify that LiDAR doesn't operate independently; it typically consists of three main modules: a laser emitter, a receiver, and an inertial positioning and navigation system. When LiDAR is working, it emits a laser beam. Upon encountering an object, the laser beam is reflected back to the CMOS sensor for reception, allowing the system to measure the distance between the object and the target. In principle, knowing the speed of light and the time from emission to CMOS sensing allows us to measure the distance to the obstacle. Then, combining this with real-time GPS and calculating the LiDAR's emission angle, the system can obtain the coordinates, direction, and distance information of the object ahead.
Then, if a lidar can emit multiple lasers from a set angle within the same space, it can obtain multiple obstacle-based reflection signals. Combined with the time range, laser scanning angle, GPS location, and INS data processing information (x, y, z coordinates), this information becomes three-dimensional signals such as distance and spatial location. Based on software algorithm combinations, the system can obtain relevant parameters such as lines, surfaces, and body elements, establish a three-dimensional point cloud map, and draw an environmental map, thus becoming the "eyes" of a car.
III. LiDAR Industry Chain
1) Transmitter Chips: Osram's dominant position in the 905nm EEL chip family is hard to change, but VCSELs, after making up for the power shortcomings through multi-junction technology, will gradually replace EELs due to their low cost and low temperature drift characteristics. Domestic chip manufacturers such as Changguang Huaxin and Zonghui Xinguang are ushering in development opportunities.
2) Receiver: Due to the need to increase the detection range for the 905nm route, it is expected that the SiPM and SPAD routes will continue to use APD for the 1550nm route. Currently, Sony, Hamamatsu, and ON Semiconductor mainly monopolize related products with high barriers to entry. The 1550nm Chipstar and the 905nm Lingming Photonics are expected to be the first to break through Nanjing Nuclear Vision.
3) Calibration end: Semiconductor laser resonators have small resonant cavities and poor beam quality. To meet lidar standards, direct optical calibration along the fast and slow axes is required. Line light source solutions need homogenization, and a single lidar unit costs several hundred yuan.
4) TEC: Osram solved the temperature drift problem of EEL, and VCSEL naturally has low temperature floating characteristics, so LiDAR no longer needs TEC.
5) Scanning end: The main barrier to timing control of the rotating mirror is the high difficulty of MEMS process. Xijing Technology was the first to achieve mass production.
