Measurement principles and methods of laser rangefinder
1 What is the principle of using infrared ranging or laser ranging?
The principle of ranging can basically be summarized as measuring the time it takes for light to return to the target, and then calculating the distance D through the speed of light c=299792458m/s and the atmospheric refractive index n. Since it is difficult to directly measure time, the phase of a continuous wave is usually measured, which is called a phase-measuring distance meter. Of course, there are also pulse rangefinders, the typical one is WILD's DI-3000
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. There is a handheld laser rangefinder used in the construction industry for house surveying that works on the same principle.
2. Does the plane of the measured object have to be perpendicular to the light?
Usually precise distance measurement requires the cooperation of a total reflection prism, but the rangefinder used for house measurement directly measures the reflection of a smooth wall, mainly because the distance is relatively close and the signal strength of the light reflection is strong enough. It can be known from this that it must be vertical, otherwise the return signal will be too weak and the maximum distance cannot be obtained.
3. Is it okay if the plane of the measured object is diffusely reflective?
This is usually possible. In actual projects, thin plastic plates are used as reflective surfaces to solve the problem of serious diffuse reflection.
4. The accuracy of ultrasonic ranging is relatively low and is rarely used now.
Main categories
One-dimensional laser range finder is used for distance measurement and positioning;
Scanning Laser Range finder
3D Laser Range finder
