Principle Classification and Application of Handheld Laser Rangefinder
a introduction
The laser rangefinder is an instrument that uses laser to accurately measure the distance of the target. When the laser range finder is working, it emits a very thin laser beam to the target, and the photoelectric element receives the laser beam reflected by the target. The timer measures the time from the launch to the reception of the laser beam, and calculates the distance from the observer to the target.
If the laser is emitted continuously, the measurement range can reach about 40 kilometers, and the operation can be carried out day and night. If the laser is emitted in pulses, the general accuracy is low, but for long-distance measurement, it can achieve good relative accuracy
The world's first laser was successfully developed in 1960 by Maiman, a scientist from the Hughes Aircraft Company of the United States. The U.S. military quickly launched research on laser devices on this basis. In 1961, the first laser range finder passed the demonstration test of the US military, after which the laser range finder soon entered the practical complex.
The laser rangefinder is light in weight, small in size, easy to operate, fast and accurate, and its error is only one-fifth to several hundredths of other optical rangefinders, so it is widely used in terrain measurement, battlefield measurement, tank , Aircraft, ships and artillery to the target range, measuring the altitude of clouds, aircraft, missiles and artificial satellites, etc. It is an important technical equipment to improve the accuracy of high tanks, aircraft, ships and artillery.
Due to the continuous reduction in the price of laser range finders, the industry has gradually begun to use laser range finders. At home and abroad, a batch of new miniature rangefinders with the advantages of fast ranging, small size and reliable performance have emerged, which can be widely used in industrial measurement and control, mines, ports and other fields.
2. Measuring principle and method of laser range finder
1 What is the principle of infrared ranging or laser ranging?
The principle of ranging can basically be attributed to measuring the time required for light to go back and forth to the target, and then calculate the distance D through the speed of light c=299792458m/s and the atmospheric refraction coefficient n. Because it is difficult to measure time directly, it is usually to measure the phase of continuous wave, which is called phase measuring range finder. Of course, there are also pulse rangefinders, typically 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. The construction industry has a handheld laser distance meter for house surveying that works on the same principle.
2 Must the plane of the measured object be perpendicular to the light?
Usually precision distance measurement requires the cooperation of a total reflection prism, while the rangefinder used for house measurement directly measures with smooth wall reflection, mainly because the distance is relatively short and the signal strength of the light reflected back is large enough. It can be known from this that it must be vertical, otherwise the return signal is too weak and the maximum distance cannot be obtained.
3. Is it possible if the plane of the measured object is diffuse reflection?
It is usually possible. In actual engineering, a thin plastic plate is used as a reflective surface to solve the problem of serious diffuse reflection.
4. The accuracy of ultrasonic ranging is relatively low, and it is rarely used now.
Three main categories
One-dimensional laser rangefinder for distance measurement and positioning;
Two-dimensional laser range finder (Scanning Laser Range finder)
3D Laser Range finder
