Understand the characteristics and main players of the four types of lidar in one article

Since its birth, the lidar industry has kept up with the cutting-edge development of underlying devices. With the development of lidar technology, from single-point lidar to solid-state lidar and FMCW lidar with innovative technical solutions, lidar has always been favored by industries such as consumer electronics, unmanned driving, robotics, and Internet of Vehicles. pay attention to.

In 2020, Apple includes dToF lidar modules on the new iPad Pro, iPhone 12 Pro and iPhone 12 Pro Max. Let lidar spark public discussion again.

Although the lidar on Apple products is also based on the time-of-flight principle, from the perspective of product requirements and customer groups, lidar for consumer electronics applications is very different from lidar for unmanned, advanced assisted driving, robotics, and Internet of Vehicles applications. . In particular, consumer electronics have stricter requirements on the volume and power consumption of lidar modules.

Since its birth, the lidar industry has kept up with the cutting-edge development of underlying devices. With the development of lidar technology, from single-point lidar to solid-state lidar and FMCW lidar with innovative technical solutions, lidar has always been favored by industries such as consumer electronics, unmanned driving, robotics, and Internet of Vehicles. pay attention to.

At present, lidar is usually divided into mechanical lidar, pure solid-state lidar, and semi-solid lidar. Among them, semi-solid radars are represented by three types: rotating mirror type, rotating mirror type and galvanometer type. The solid-state lidar mainly has three technical directions: MEMS, OPA, and Flash.

Mechanical lidar

The classic architecture of mechanical lidar is mainly to drive the overall rotation of the optical-mechanical structure through the motor, which is generally carried out in the aspects of increasing the number of system channels, expanding the ranging range, improving the spatial angle resolution, and improving the system integration and reliability. technological innovation. Mechanical LiDAR has the advantages of fast scanning speed, small receiving field, strong anti-light interference ability, and high signal-to-noise ratio. The disadvantage is that it is expensive, optical path debugging, complex assembly, long production cycle, and low reliability in driving environment.

Semi-solid lidar

Semi-solid lidar can be divided into rotating mirror type, micro-galvo mirror type and so on. Among them, the rotating mirror type keeps the transceiver module stationary, allowing the motor to reflect the light beam to a certain range of space in the process of driving the rotating mirror to move, so as to realize scanning detection. Its technological innovation is similar to that of mechanical lidar.

The micro-galvanometer type mainly uses a high-speed vibrating two-dimensional galvanometer to scan and measure a certain range of space. In terms of technological development, it focuses on the development of a galvanometer with a larger aperture, higher frequency and better reliability, which is suitable for lidar. The micromirror has a small vibration amplitude, high frequency, low cost, and mature technology, which is suitable for mass production and large-scale applications.

Pure solid-state lidar

It is generally believed that there are only two pure solid-state lidars, one is optical phased array OPA, and the other is Flash. OPA is an optical phased array technology, which adjusts the phase relationship of each phased unit by applying a voltage, and uses the coherence principle to realize the deflection of the emitted beam, so as to complete the scanning measurement of a certain range of space by the system.

The Electronic scanning type mainly realizes scanning by sequentially driving the transceiver units of different fields of view in time sequence, and there are no mechanical moving parts in the system. Its architecture is more advanced than the Flash solid-state lidar that exposes all transceiver units as a whole.

Flash lidar mainly emits a large area of ​​laser covering the detection area directly in a short time, and then uses a highly sensitive area array receiver to complete the drawing of images around the environment.

Pure solid-state lidar is considered to be the future development trend of lidar due to its fast scanning speed, high precision, good controllability, and small size, but pure solid-state lidar technology is not fully mature.

FMCW lidar

FMCW lidar transmits frequency-modulated continuous laser, and obtains the frequency difference through coherent beat frequency between the echo signal and the reference light, thereby indirectly obtaining the time-of-flight inverse distance of the target, and can also directly measure the speed of the target according to the Doppler frequency shift information. , The technical development direction is to use silicon-based optoelectronic technology to realize the chipization of lidar system.

FMCW lidar can achieve higher detection sensitivity and accuracy, suitable for low-cost mass production of silicon photonics and phased array technology, and can effectively block the interference of other radars. However, the high requirements on the power consumption processing capability of the components are the basic factors that limit this technology. In order to gain market acceptance, the lasers must be in FM speed, FM range, linearity, laser coherence, meet vehicle regulations and be able to Progress has been made in many aspects such as low-cost mass production.

Based on the advantages and disadvantages of different lidars, domestic and foreign manufacturers choose different camps in terms of technology.

At present, the main players of mechanical lidar are: Hesai, Velodyne, Sagitar, Ouster, etc.

The main players of hybrid solid-state lidar are: MEMS-based Sagitar, Innoviz, mirror-based DJI Livox, Valeo, Luminar, etc.

And pure solid-state lidar players include: Quanergy, Ibeo, etc.

Solid-state lidar is the future trend, with the advantages of miniaturization and low cost. Solid-state LiDAR requires no rotating parts, making it smaller, easier to integrate inside the body, and significantly reducing costs as system reliability increases. Therefore, LiDAR has a trend towards solid-state development.

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Author: Yoyokuo