1. What is the principle of using infrared or laser ranging?
The principle of ranging can basically be summed up as measuring the time required for light to travel back and forth to the target, and then calculating the distance D by the light speed c=299792458m/s and the atmospheric refraction coefficient n. Because it is difficult to measure the time directly, it is usually to measure the phase of a continuous wave, which is called a phase measuring rangefinder. Of course, there are also pulse rangefinders, typically the DI-3000 of WILD.
It should be noted that the phase measurement is not to measure the phase of infrared or laser light, but to measure the phase of the signal modulated on infrared or laser light. There is a hand-held laser rangefinder in the construction industry, which is used to measure houses, and its working principle is the same.
2. Must the plane of the measured object be perpendicular to the light?
Usually, precision distance measurement needs the cooperation of total reflection prism, while the distance meter used for house measurement directly uses smooth wall reflection measurement, mainly because the distance is relatively close and the signal intensity of light reflection is large enough. Therefore, it must be vertical, otherwise the return signal is too weak to get the accurate distance.
3. Is it ok if the plane of the measured object is diffuse reflection?
Usually, it is also possible. In practical engineering, the thin plastic plate will be used as the reflecting surface to solve the serious diffuse reflection problem.
4. Ultrasonic ranging accuracy is relatively low, and it is rarely used now.
5. The accuracy of laser rangefinder can reach 65438±0mm error, which is suitable for various high-precision measurement purposes.