The measurement principle and method of laser rangefinder
What is the principle of using infrared or laser ranging?
The principle of distance measurement can be summarized as measuring the time required for light to travel back and forth to the target, and then calculating the distance D through the speed of light c=299792458m/s and atmospheric refractive index n. Due to the difficulty of directly measuring time, it is usually to measure the phase of continuous waves, which is called a phase measuring rangefinder. Of course, there are also pulse rangefinders, typical of which are WILD's DI-3000
It should be noted that phase measurement is not about measuring the phase of the infrared or laser, but rather measuring the phase of the signal modulated on the infrared or laser. There is a handheld laser rangefinder used in the construction industry for house measurement, which works on the same principle.
2. Does the plane of the tested object have to be perpendicular to the light?
Usually, precision ranging requires the cooperation of a total reflection prism, and the rangefinder used for house measurement directly reflects the measurement from a smooth wall surface, mainly because the distance is relatively close and the signal strength reflected back by the light is strong enough. It can be inferred that it must be perpendicular, otherwise the return signal will be too weak to obtain accurate distance.
3. If the plane of the tested object is diffuse reflection, is it possible?
Usually, it is also possible to use thin plastic sheets as reflective surfaces in practical engineering to solve the problem of severe diffuse reflection.
4. Ultrasonic ranging accuracy is relatively low and is rarely used nowadays.
Measurement principles and methods of action
With the development of technology, it seems that most people are still unaware of the existence of laser rangefinders and do not understand them. Even some workers are using tape measures to measure distances, calculating areas, volumes, and so on with pens. Below, I will introduce the principle and usage of laser rangefinder, which can enable workers to work and learn with high efficiency and precision.
Laser rangefinder is an instrument that uses laser to accurately measure the distance of a target. The laser rangefinder emits a very fine laser beam towards the target during operation, and the photoelectric element receives the reflected laser beam from the target. The timer measures the time from the laser beam to the receiving point and calculates the distance from the observer to the target.
If the laser is continuously emitted, the measurement range can reach about 40 kilometers and operations can be carried out day and night. If the laser is pulsed, the accuracy is generally low, but when used for long-distance measurement, it can achieve good relative accuracy.
