Analysis on Measurement Principle and Method of Laser Range Finder

Laser rangefinder is an instrument that uses laser to accurately measure the policy distance. During operation, the laser rangefinder emits a very thin beam of laser rangefinder light to the policy, and the photoelectric element receives the laser beam reflected by the policy. The timer measures the time from emission to reception of the laser beam and calculates the distance from the observer to the policy. If the laser is continuously emitted, the measuring range can reach about 40 kilometers, and the fluorine-lined butterfly valve can operate day and night. If the laser is pulsed, the accuracy is generally lower, but for long distance measurement, it can reach a good relative accuracy. The world's first laser was first developed in 1960 by American Hughes Aircraft Company scientist Meiman.

The U.S. military soon started discussions on military laser equipment on this basis. In 1961, Taiwan's top military laser rangefinder passed the U.S. military certification test and soon entered a useful consortium. Laser rangefinders are light in weight, small in size, simple in operation, fast and accurate, and their faults are only 1/5 to 1/100 of those of other optical rangefinders. Therefore, they are widely used in topographic survey, battlefield survey, range finding of tanks, planes, ships and artillery on policies, and height measurement of clouds, planes, missiles and artificial satellites. It is an important technical equipment with high precision for tanks, planes, ships and artillery. Because the price of laser rangefinders has been continuously lowered, the industry has gradually begun to use laser rangefinders. At home and abroad, a number of new micro range finders have emerged with the advantages of fast ranging, small size and reliable function, which can be widely used in industrial measurement and control, mines, ports and other fields. First classification One-dimensional laser rangefinder is used for distance measurement and positioning. Two-dimensional laser range finder is used in inductive measurement, location, area monitoring and other fields. Three-dimensional laser range finder is used in three-dimensional inductive measurement, three-dimensional spatial positioning and other fields.

1. What is the principle of infrared or laser ranging?

The principle of distance measurement can be summed up as the time required to measure the light reciprocating policy, and then the distance d can be calculated through the speed of light c=299792458m/s and the atmospheric refractive index 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 range finders, typically WILD's DI-3000. Phase measurement does not measure the phase of infrared or laser light, but the phase of the signal modulated on the infrared or laser light. There is a kind of hand-held laser range finder for building work, which is used for house measurement. Its working principle is the same as this.

2. Is it necessary for the plane of the measured object to be perpendicular to the light?

General precision ranging requires the cooperation of total reflection prisms, while the rangefinder used for house measurement is directly measured by smooth wall reflection, mainly because the distance is relatively close and the signal intensity reflected by light is large enough. From this, we can know that it must be vertical, otherwise the return signal is too small to get accurate distance.

3. If the plane of the measured object is diffuse reflection, can it be?

Generally, it is also possible. In practical projects, thin plastic plates will be selected as the reflecting surface to deal with the severe diffuse reflection problem.