What is a laser rangefinder?

The laser rangefinder (Laser rangefinder) is an instrument that uses a certain parameter of the modulated laser to measure the distance to the target. The laser rangefinder has a measuring range of 3.5 to 5000 meters.

According to the distance measurement method, it is divided into phase method rangefinder and pulse method rangefinder. The pulsed laser rangefinder emits a beam or a sequence of short pulsed laser beams to the target when it is working, and the photoelectric element receives the laser light reflected by the target. The timer measures the time from emission to reception of the laser beam, and calculates the distance from the observer to the target. The phase method laser rangefinder detects the distance by detecting the phase difference that occurs when the emitted light and the reflected light propagate in space. The laser rangefinder is light in weight, small in size, simple to operate, fast and accurate, and its error is only one-fifth to one-hundredth of other optical rangefinders.

Introduction

The laser rangefinder is an instrument that uses a certain parameter of the modulated laser to accurately measure the distance to the target. The pulsed laser rangefinder emits a beam or a sequence of short pulsed laser beams to the target when it is working. The photoelectric element receives the laser beam reflected by the target. The distance from the instrument to the target.

When the power of the emitted laser beam is sufficient, the measurement range can reach about 40 kilometers or more. The laser rangefinder can operate day and night, but when there are substances with high laser absorption rate in the space, the distance and accuracy of the ranging will be reduced.

The first laser in the world was a ruby laser developed by Mayman, a scientist at Hughes Aircraft Corporation of the United States, in 1960. The US military quickly carried out research on military laser devices on this basis. In 1961, the first military laser rangefinder passed the U.S. military demonstration test, after which the laser rangefinder soon entered the practical stage.

As the price of laser rangefinders continues to drop, the industry has gradually begun to use laser rangefinders. A number of new miniature rangefinders with the advantages of fast ranging, small size, and reliable performance have emerged at home and abroad, which can be widely used in industrial measurement and control, mines, ports and other fields.

Laser is a new technology developed in the 1960s. It is a light with very pure color, high concentration of energy, and good directionality. A laser rangefinder is an instrument that uses lasers for distance measurement. Its principle of action is very simple: the distance is measured by measuring the time from when the laser light is emitted to when the laser light is reflected back from the target. For example, a laser rangefinder is used to measure the distance of the moon. If the time from the start of the laser emission to the reflection from the moon is determined to be 2.56 seconds, the one-way time of the laser emission to the moon is equal to 1.28 seconds, and the speed of the laser is the speed of light, which is equal to 300,000 kilometers per second. Therefore, the measured distance from the moon to the earth is the product of the one-way time and the speed of light, which is 384,000 kilometers. In order to emit and receive laser light, and to perform timing, laser rangefinder is composed of laser transmitter, receiver, clock frequency oscillator and distance counter.

Laser rangefinders can also be used to track and range artificial satellites, measure the altitude of aircraft, aim and range targets, and conduct terrain mapping and surveys.

Principle

1.Using the principle of infrared ranging or laser ranging

The principle of ranging can basically be attributed to the measurement of the time required for the light to go back and forth to the target, and then the distance D is calculated by 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 a phase measuring rangefinder. Of course, there are also pulsed rangefinders.

It should be noted that the phase measurement is not measuring the phase of infrared or laser, but measuring the phase of the signal modulated on infrared or laser. There is a hand-held laser rangefinder in the construction industry for house surveying, and its working principle is the same.

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

Usually precision ranging requires the cooperation of total reflection prisms, and the rangefinder used for house measurement directly uses smooth wall reflection to measure, mainly because the distance is relatively short, and the signal intensity 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 precise distance cannot be obtained.

3. It can measure the surface of the object as diffuse reflection

Usually, it is also possible. In actual engineering, a thin plastic plate is used as a reflecting surface to solve the serious problem of diffuse reflection.

4. The entertainment-grade pulse method laser rangefinder can achieve a display accuracy of 1 meter, a measurement rangefinder can achieve accuracy of ±1 meter, ±0.1 meter, and ±0.15 meter.

5. The accuracy of the phase laser rangefinder can reach an error of 1 mm, which is suitable for various high-precision measurement purposes.