A laser rangefinder is an instrument that uses lasers to accurately measure the distance to a target. The laser rangefinder emits a very fine laser beam to the target during operation. The photoelectric element receives the laser beam reflected by the target, and the timer measures the time from emission to reception of the laser beam to calculate the distance from the observer to the target. The laser rangefinder is light in weight, small in size, simple to operate, fast and accurate, and the error is only one-fifth to one-hundredth of other optical rangefinders.

principle

1. Using infrared ranging or laser ranging principle

The principle of ranging can basically be attributed to the measurement of the time required for the light to enter and exit the target, and then calculate the distance D through the speed of light c=299792458 m/s and the atmospheric refractive index n. Because it is difficult to directly measure the time, the phase of continuous wave is usually measured. It is a phase measuring range detector. Of course, there is also a pulse rangefinder, usually the DI-3000 of WILD.

It should be noted that the phase measurement is not measuring the phase of infrared or laser, but measuring the phase of a signal modulated on infrared or laser. The construction industry has a handheld laser rangefinder for house surveying, which works in the same way.

2. The plane of the object must be perpendicular to the light.

Generally, precision ranging requires a total reflection prism to match, and the rangefinder used for house measurement is directly measured by reflection from a smooth wall, mainly because the distance is relatively close and the signal intensity reflected by the light is large enough. It can be known that it must be vertical, otherwise the return signal will be too weak to obtain a precise distance.

3. The plane of the object can be measured as diffuse reflection

Usually it is also possible. In actual engineering, thin plastic plates are used as reflective surfaces to solve serious diffuse reflection problems.

4. Ultrasonic ranging accuracy is relatively low, and the use is relatively small.

5. The laser rangefinder can reach an accuracy of 1 mm and is suitable for various high-precision measurements.