Laser range finder measures distance in two ways: the principle of pulse method and phase method
The new laser range finder uses two methods to measure distance: the principle of pulse method and phase method
The 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 range finders, usually a long cylinder, composed of objective lens, eyepiece, display device (can be built in), battery and other parts.
The laser rangefinder can also emit multiple laser pulses to determine whether the object is moving away from or approaching the light source through the Doppler effect.
The principle of range finder
Laser range finders 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 measured object and then received by the range finder, and the range finder records the time of the laser to and fro at the same time. Half of the product of the speed of light and the round-trip time is the distance between the rangefinder and the measured object. The accuracy of distance measurement by pulse method is generally around +/-1 meter. In addition, the measurement blind zone of this type of rangefinder is generally about 15 meters.
Laser distance measurement is a method of distance measurement in light wave distance measurement. If light travels in the air at speed c and takes time t to go back and forth between two points A and B, then the distance D between points A and B can be used as follows express.
D=ct/2
In the formula:
D--the distance between two points A and B of the station site;
c - the speed of light propagating in the atmosphere;
t--the time required for light to go 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 different measurement methods, laser range finders can usually be divided into two types of measurement: pulse type and phase type.
Phase Laser Range Finder
The phase laser rangefinder uses the frequency of the radio band to modulate the amplitude of the laser beam and measure the phase delay caused by the modulated light going back and forth to the survey line once, and then convert the distance represented by the phase delay according to the wavelength of the modulated light. That is, the indirect method is used to measure the time required for the light to go back and forth through the measuring line, as shown in the figure.
The phase laser rangefinder is generally used in precision distance measurement. Due to its high precision, generally at the millimeter level, 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 reflector called a cooperative target. mirror.
