Analysis on the measuring principle and method of laser rangefinder

The laser rangefinder is an instrument that uses lasers to accurately measure the distance to a target. The laser rangefinder emits a very thin laser rangefinder light to the target when it is working. The photoelectric element receives the laser beam reflected by the target. The timer measures the time from emission to reception of the laser beam, and calculates the time from the observer to the The distance to the target. If the laser is fired continuously, 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 low, but for long-distance measurement, it can achieve good relative accuracy. The laser in the world was first successfully developed by Mayman, a scientist at Hughes Aircraft Corporation in the United States in 1960.

    The US military quickly carried out research on military laser devices on this basis. In 1961, Taiwan's military laser rangefinder passed the U.S. military demonstration test, after which the laser rangefinder soon entered the practical complex. 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, so it is widely used in terrain surveying, battlefield surveying, and tanks. , The distance measurement of aircraft, ships and artillery to the target, the measurement of the height of clouds, aircraft, missiles and artificial satellites. It is an important technical equipment to improve the accuracy of high tanks, aircraft, ships and artillery. 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.
    The main categories are one-dimensional laser rangefinders for distance measurement and positioning; two-dimensional laser rangefinders (Scanning Laser Rangefinder) for contour measurement, positioning, area monitoring and other fields; three-dimensional laser rangefinders (3D Laser Rangefinder) for Three-dimensional contour measurement, three-dimensional space positioning and other fields.
    Measuring principle and method of laser rangefinder using laser to measure the distance from the moon to the earth
    1. What is the principle of using 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. The typical DI-3000 of WILD needs attention. Phase measurement is not to measure the phase of infrared or laser, but to measure 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. Must the plane of the measured object 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 distance cannot be obtained.
    3. Is it okay if the plane of the measured object is 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. Ultrasonic ranging accuracy is relatively low, and it is rarely used now.