Lidar is actually a kind of work in the optical band (special band) of the radar, its advantages are very obvious:

1. With a very high resolution: high power laser radar work in the optical band, the frequency is higher than the microwave 2 to 3 orders of magnitude above, therefore, compared with the microwave radar, laser radar has a very high distance resolution, angular resolution and speed Resolution;

2. The anti-interference ability: the laser wavelength is short, can launch the divergence angle is very small (μ rad order) of the laser beam, multi-path effect is small (no directional emission, and microwave or millimeter wave multipath effect), can detect Low altitude / low altitude target;

3. Access to the amount of information: can directly access the target distance, angle, reflection intensity, speed and other information to generate the target multi-dimensional image;

4. Can work all day: laser active detection, does not depend on external lighting conditions or the target itself, the radiation characteristics. It only needs to launch its own laser beam, by detecting the emission of the laser beam echo signal to obtain the target information.

If the system is divided from the main, there are direct detection of lidar and coherent detection of lidar. In fact, what we are currently referring to, including automatic driving, robots, mapping used in the lidar, basically belong to this type of direct detection of the lidar. There are more special, such as wind, speed and the like radar, the general will use coherent system.

By application classification, we can share more, such as: blue laser range finder, laser three-dimensional imaging radar, laser radar, laser atmospheric radar, and so on.

According to the principle of distance measurement, there are two ways:

1. One is TOF technology, that is, Time of Flight. It is a way of measuring the time of light flight. In this way, the name suggests is to emit a laser, and then there will be a diode for green laser pointer echo detection, we then use a very high-precision timer to measure the light emitted to the target to cause feedback back to the time difference, but we It is known that the speed of light has invariance, and then the time difference multiplied by the speed of light can get the target object distance.

2. There is another new measurement method - triangulation method. This approach is essentially a method based on image processing.