The principle and use of laser range finder
The laser range finder is an instrument that uses a certain parameter of the modulated laser to accurately measure the distance of the target. The pulsed laser rangefinder emits a beam or a sequence of short-term pulsed laser beams to the target when it is working, and the photoelectric element receives the laser beam reflected by the target. The timer measures the time from the launch to the reception of the laser beam, and calculates The distance from the meter to the target.
The principle and application of the laser rangefinder
1. The principle of using infrared ranging or laser ranging
The principle of ranging can basically be attributed to measuring the time required for light to go back and forth to the target, and then calculate the distance D through the speed of light c = 299792458m/s and the atmospheric refraction coefficient n. Because it is difficult to measure time directly, it is usually to measure the phase of continuous wave, which is called phase measuring range finder. Of course, there are also pulsed rangefinders.
It should be noted that phase measurement does not measure the phase of infrared or laser, but the phase of the signal modulated on infrared or laser. The construction industry has a handheld laser distance meter for house surveying that works on the same principle.
2. The plane of the measured object must be perpendicular to the light
Usually precision distance measurement requires the cooperation of a total reflection prism, while the rangefinder used for house measurement directly measures with smooth wall reflection, mainly because the distance is relatively short and the signal strength of the light reflected back is strong enough. It can be known from this that it must be vertical, otherwise the return signal is too weak and the distance cannot be obtained.
3. The object plane can be measured as diffuse reflection
It is usually possible. In actual engineering, a thin plastic plate is used as a reflective surface to solve the problem of serious diffuse reflection.
4. The accuracy of the phase laser range finder can reach 1 mm error, which is suitable for various high-precision measurement purposes.
5. The entertainment-grade products of the pulse method laser range finder can achieve a display accuracy of 1 meter, a measurement accuracy of ±1 meter, and a measurement-grade product with a display accuracy of 0.1 meters and a measurement accuracy of ±0.15 meters.
