What are the principles and methods of laser guidance?

Laser guidance, in layman's terms, is to control the flight of missiles with lasers and guide them to reach their targets. There are three ways: laser beam guidance, semi-active laser guidance and full-active laser guidance.

Laser beam guidance means that the laser beam emitted by the laser irradiator aims at and tracks the target, and the missile always stays at the center of the laser beam in the process of flying to the target. If the missile deviates from this center, the laser receiver installed at the tail of the missile will send out a deviation signal, and then the control system will correct the trajectory deviation. This guidance method requires strict coordination between laser beam and missile launching direction, which is technically difficult, but the whole system is small and light, suitable for individual use. This is a successfully developed guidance method, which is mainly used to prevent low-altitude missiles.

Semi-active laser guidance is to use a laser illuminator installed on the ground or aircraft to emit a laser beam to the target (indicating the target). The laser signal reflected from the target surface is received by the target detector (that is, the laser receiver) installed on the missile head, and then the missile or projectile is guided to the target through the control system. This guidance method is mostly used in laser guidance system to deal with ground targets, such as laser-guided bombs, air-to-ground missiles, air-to-ground anti-tank missiles and laser-guided artillery shells. Semi-active laser guidance mode has great maneuverability and flexibility, and it is also a successful laser guidance mode at present.

Fully active laser guidance; Both the laser radiator and the target detector are installed on the bomb. The laser irradiator emits laser to the target, and the target seeker receives the laser signal reflected by the target, and then guides the missile to the target through the control system on the missile. This is an ideal guidance method, especially suitable for terminal guidance, but its development is not mature at present.