Laser ranging sensors are divided into two categories: triangulation and time-of-flight methods. Time-of-flight laser ranging can be divided into three types: pulsed laser ranging, phase-based laser ranging and interferometric laser ranging.

1. Pulse laser ranging

Pulsed laser ranging sensor technology takes advantage of the relatively concentrated energy of laser pulses in time, and the instantaneous power is very large (usually up to watts). In the case of cooperative targets, pulsed laser ranging can achieve edge measurement, and general-purpose pulsed laser ranging sensors can measure distances of tens or even tens of thousands of kilometers, achieving a measurement accuracy of more than 10 cm. When performing a short-range range from a few kilometers to several tens of kilometers, even if the cooperative target is not used, the distance measurement can be performed only by using the measurement target to diffusely reflect the signal to the pulse tube. The disadvantage is that the absolute ranging accuracy is not very high.

2. Phase laser ranging

The phase laser ranging sensor uses a fixed frequency high frequency sinusoidal signal to continuously modulate the luminous intensity of the laser source, and measures the phase delay generated by the modulated laser back and forth once. The measured distance is calculated from the phase delay.

Phase-based ranging is to indirectly measure the signal propagation time by measuring the phase delay generated by the continuous amplitude modulated signal propagating back and forth over the distance to be measured, thereby obtaining the measured distance. This method has high measurement accuracy, usually on the order of millimeters.

3. Interferometric laser ranging

The interferometric ranging method is also a phase ranging method. The difference from the general phase ranging method is that it does not measure the distance by measuring the phase of the laser modulation signal, but measures the distance by measuring the interference fringe changes. The laser itself.