Working Principle Of Pulsed And Continuous Wave Laser Distance Meter
At present, there are many types of laser rangefinders with different functions, but from the perspective of operation mode (or operating principle), pulse laser rangefinders and continuous wave laser rangefinders are nothing more than two types. The following is a description of the principles and characteristics of two types of rangefinders:
(1) Pulse laser ranging.
The principle of pulse laser ranging is to use a pulse laser to emit a very narrow series of light pulses (pulse width less than 50ns) towards the target, and the light is locally reflected after reaching the surface of the target. After measuring the time from emission to receiver of the light pulse, the interval between the rangefinder and the target can be calculated. Assuming the measurement interval is h, the reciprocating time of the light pulse is t, and the propagation speed of light in the air is c, then:
h=ct/2
Pulse laser rangefinder can emit strong laser light. Distance measurement can be very strong. Even with non cooperative policies, the maximum distance can reach over 30000 meters. Its ranging accuracy is generally 5 meters, with a maximum of 0.15 meters. Pulse laser rangefinder can not only be used for ranging in various non cooperative military policies, but also for measuring visibility and cloud height in climate, as well as fine interval measurement of artificial satellites.
(2) Continuous wave laser ranging.
Continuous wave laser rangefinders generally use the phase method for distance measurement. The principle is to first emit a modulated continuous wave laser beam to the target, which is reflected after reaching the surface of the target. By measuring the phase difference between the emitted continuous wave laser beam and the receiver's received echo, the distance between the target and the rangefinder can be obtained.
