Difference between solid-state lidar and mechanical lidar

The so-called solid-state lidar is generally recognized as a non-rotating solid-state lidar. It is usually divided into three ways, based on phased array, Flash and MEMS.

The solid-state laser radar is realized by using the principle of phased array, and the mechanical structure is completely cancelled. The exit angle of laser is changed by adjusting the phase difference of each transmitting unit in the transmitting array. Optical phased array generally realizes beam pointing scanning by strictly controlling the phase of electrical signals, so it can also be called electronic scanning technology. However, it is also easy to form sidelobes, which affect the working distance and angular resolution of the beam and are difficult to produce.

Solid-state lidar using 3D Flash technology belongs to non-scanning radar. It emits surface light and is a kind of lidar with 2d or 3D images as its output content. Although the stability and cost are good, the main problems are short detection distance and poor technical reliability.

The solid-state laser radar based on MEMS scans by changing the emission angle of a single emitter through a micro-vibration mirror, thus forming a scanning field of view of an area array. At present, many manufacturers are developing laser radar based on MEMS. Compared with the first two, MEMS is technically easier to realize and its cost is lower. Therefore, it has also been unanimously optimistic about the host manufacturers.

Solid state lidar has many advantages. First of all, it is simple in structure and small in size. Because there is no need for rotating parts, the structure and size of radar can be greatly reduced, its service life can be prolonged and its cost can be reduced. Secondly, because the optical structure of mechanical lidar is fixed, it is often necessary to adjust its position and angle accurately to adapt to different vehicles, while solid-state lidar can be adjusted by software, which greatly reduces the difficulty of calibration and speeds up the scanning speed and accuracy.

However, solid-state lidar also has its corresponding shortcomings. Solid-state lidar means that it can't rotate 360 degrees and can only detect the front. Therefore, in order to realize omni-directional scanning, it is necessary to arrange multiple solid-state lidar in different directions. In addition, solid-state lidar still can't solve the shortcoming that it can't display performance in extreme climate. If combined with all-weather millimeter wave radar, the detection performance of self-driving cars will be greatly improved.