The new laser rangefinder measures distance in two ways: the principle of pulse method and phase method
The new laser rangefinder uses two methods to measure distance: the pulse method and the phase method principle
A rangefinder is a tool for measuring length or distance, and can be combined with angle measuring equipment or modules to measure parameters such as angle and area. There are many forms of rangefinders, usually a long cylinder, which consists of an objective lens, an eyepiece, a display device (which can be built in), a battery and other parts.
Laser rangefinders can also fire multiple laser pulses, using the Doppler effect to determine whether an object is moving away or approaching the light source.
The principle of rangefinder
Laser rangefinders generally use two methods to measure distance: pulse method and phase method. The process of pulse method ranging is as follows: the laser emitted by the range finder is reflected by the object to be measured and then received by the range finder, and the range finder records the time of the laser round trip at the same time. Half the product of the speed of light and the round-trip time is the distance between the rangefinder and the object being measured. The accuracy of the distance measurement by the pulse method is generally around +/- 1 meter. In addition, the measurement blind area of this type of rangefinder is generally about 15 meters.
Laser ranging is a kind of ranging method in light wave ranging. If the time required for light to travel back and forth between points A and B at a speed c is t, then the distance D between points A and B can be as follows: express.
D=ct/2
In the formula:
D--the distance between the two points A and B of the measuring station;
c--the speed of light traveling in the atmosphere;
t--the time it takes for light to travel back and forth between A and B once.
It can be seen from the above formula that to measure the distance between A and B is actually to measure the time t of light propagation. According to the different measurement time methods, laser rangefinders can usually be divided into two measurement forms: pulse type and phase type.
Phase laser rangefinder
The phase laser rangefinder uses the frequency of the radio band to modulate the amplitude of the laser beam and measure the phase delay produced by the modulation light going back and forth to the measuring line once, and then convert the distance represented by the phase delay according to the wavelength of the modulated light. That is, the time required for the light to travel back and forth through the line is measured by an indirect method, as shown in the figure.
Phase laser rangefinders are generally used in precision ranging. Due to its high accuracy, generally in the order of millimeters, in order to effectively reflect the signal and limit the measured target to a specific point commensurate with the accuracy of the instrument, this rangefinder is equipped with a reflection called a cooperative target. mirror.
