Laser ranging sensor classification
Laser ranging sensor technology is divided into absolute distance measurement method and micro displacement measurement method according to the measurement range. Subdivided according to the ranging method, the absolute distance ranging method mainly includes pulse laser ranging and phase laser ranging, and the micro displacement measurement mainly includes triangulation laser ranging and interferometric laser ranging.
The principle of the pulse laser ranging sensor is: the pulse laser emits a pulse laser with a very short duration, and after passing the distance to be measured, it hits the target to be measured, and part of the energy will be reflected back. . The echo returns to the range finder and is received by a photodetector. According to the interval between the main wave signal and the echo signal, that is, when the laser pulse travels back and forth from the laser to the target to be measured, the distance to the target to be measured can be calculated.
The principle of the phase laser ranging sensor is: to modulate the light intensity of the emitted laser light, and use the phase change of the modulated signal when the laser space propagates. According to the wavelength of the modulated wave, the distance represented by the phase delay is calculated. That is, the indirect method of phase delay measurement is used instead of directly measuring the time required for the round trip of the laser to realize distance measurement. The accuracy of this method can reach millimeter level.
The triangulation laser ranging sensor is the light emitted by the laser, which is incident on the surface of the measured object after being focused by the converging lens, and the receiving lens receives the scattered light from the incident light point and images it on the sensitive surface of the photoelectric position detector . When the object moves, the relative distance moved by the object is calculated by the displacement of the light spot on the imaging plane. The resolution of triangulation laser ranging is very high, which can reach the order of microns.
The interferometric laser ranging sensor moves the measured target and measures the coherence, and completes the measurement of the distance increment after counting. Therefore, the sensitivity of the interferometric measurement is very high and can reach the nanometer level.
