The principle of laser ranging technology using phase and pulse methods in laser rangefinders
The principle of phase based laser ranging technology:
The mainstream laser rangefinder in the current market is based on phase method laser rangefinder. This is because laser rangefinders based on phase method can easily overcome a major drawback of ultrasonic ranging: excessive error, resulting in measurement accuracy reaching the millimeter level. The main drawbacks of laser rangefinders based on this method are complex circuits and short operating distances (around 100 meters, after the efforts of many scientific workers, there are now phase based laser rangefinders with operating distances of several hundred meters).
Phase based laser ranging technology uses laser with radio frequency band to modulate the amplitude and measure the phase difference generated by the distance between the sine modulated light and the target object. Based on the wavelength and frequency of the modulated light, the laser flight time is calculated, and then the measured distance is calculated in sequence. This method generally requires placing a reflector at the object to be measured, reflecting the laser path back to the laser rangefinder, and receiving and processing it by the discriminator of the receiving module. That is to say, this method is a passive laser ranging technology with cooperative target requirements.
The principle of pulse laser ranging technology:
The phase method is similar to the method used for ultrasonic speed and distance measurement, with a maximum measurement distance usually of a few hundred meters, which can easily reach the order of millimeters. However, the maximum measurement distance of the rangefinder designed according to this method is limited and cannot be extended. This method is mainly widely used abroad. Pulse laser ranging generally uses infrared laser, including near-infrared laser and mid infrared laser. There is a distinction between visible and invisible lasers in this wavelength range. And based on this technology, the rangefinder requires low coherence, fast speed, simple implementation structure, high peak output power, high repetition frequency, and a large range. Therefore, this project uses a pulse method to design a handheld laser rangefinder.
