Laser ranging technique

Principle of laser rangefinder
In addition to the industrial use of lasers for material processing, other fields, such as aerospace, military and other fields are also constantly developing laser applications. Among them, the laser used in aviation and military is increasing, and the laser application in this field is mainly laser ranging.The principle of laser ranging – distance is equal to speed times time.The speed of light is determined, and the travel time of light can be detected by a detection device, and the distance of the object to be measured can be calculated.

The diagram is as follows:

The laser divergence factor has great influence on the accuracy of the laser rangefinder. What is the divergence factor? For example, one person holds a flashlight and another person holds a laser pointer. The irradiation distance of the laser pointer is larger than that of the flashlight, because the flashlight light is more divergent, and the measure of the divergence of the light is called the divergence factor. Laser light is theoretically parallel, but when the action distance is far, there is divergence of light. If the divergence Angle of the light is compressed, controlling the divergence degree of the laser is a way to improve the accuracy of the laser rangefinder.

Application of laser rangefinder
Laser rangefinder is used more in aerospace, Apollo 15 on the moon with a special set of equipment – large Angle reflector, used to reflect the laser beam from the Earth, by recording the round-trip time to calculate the distance between the Earth and the moon.
At the same time, laser rangefinders are also used in other areas of aerospace:
1, laser rangefinder in the military application
Many of the optoelectronic tracking systems on fighter jets and ground equipment are equipped with laser rangefinders, which can accurately know the enemy’s distance and prepare for defense accordingly.
2, the application of laser ranging in terrain investigation and mapping
The laser rangefinder in the survey and mapping of terrain is generally called the laser altimeter, which is mainly carried on the aircraft or satellite to measure the elevation data.
3. Application of laser ranging in spacecraft autonomous landing
Using unmanned probes to land on the surface of target celestial bodies such as the moon, Mars or asteroids for field exploration or even sampling return is an important way for human to explore the universe, and it is also one of the hot spots for the development of deep space exploration activities in the future. Launching satellites or probes to soft land on the surface of other planets is an important direction for space exploration.
4. Application of laser ranging in space autonomous rendezvous and docking
Space autonomous rendezvous and docking is an extremely complex and precise process.
Rendezvous process refers to two or more aircraft meet in space orbit according to the predetermined position and time, the action distance is 100km ~ 10m, from far to near the need for GPS guidance, microwave radar, lidar, optical imaging sensor measurement means, space docking refers to two aircraft in space orbit after meeting in the mechanical structure of a whole. The operating distance is 10 ~ 0m, which is mainly accomplished by advanced video guidance sensors (AVGS).

5. Application of laser ranging in the field of space debris detection
Space debris detection is one of the important application fields of deep space laser detection technology.

Sum up
Laser is a tool! It’s also a weapon!