The principle and application of laser range finder

The laser range finder is an instrument that uses the laser to accurately measure the distance to the target. In operation, a very fine laser beam is emitted toward the target, the photoelectric element receives the laser beam reflected by the target, and the timer measures the time from the laser beam emission to the reception, and calculates the distance from the observer to the target. With the appreciation of the following Xiao Bian share a brief analysis of the laser range finder principle and application.

1. The principle of distance measurement using infrared distance measurement or laser distance measurement can basically be attributed to the time required to measure the light to and from the target, and then the distance D can be calculated by the speed of light c=299792458m/s and the atmospheric refractive index n. Because it is more difficult to measure the time directly, it is usually to measure the phase of the continuous wave, which is called a phase measuring range finder. Of course, there are also pulsed rangefinders, typically WIL-DI-3000.

It should be noted that phase measurement does not measure the phase of the infrared or laser, but instead measures the phase of the signal modulated on the infrared or laser. The construction industry has a hand-held laser range finder for house measurements, which works in the same way.

2. Field of application of laser range finder Laser range finder has been widely used in the following fields: power, water conservancy, communications, environment, construction, geology, policing, fire fighting, blasting, navigation, railway, anti-terrorism/military, agriculture, Forestry, real estate, leisure/outdoor sports etc.

3. The difference between "safe" and "unsafe" of the laser range finder As the name suggests, the laser range finder works by using the laser as the main working substance. At present, the working materials of the hand-held laser rangefinder on the market mainly include the following: semiconductor lasers with operating wavelengths of 905 nanometers and 1540 nanometers, and YAG lasers with an operating wavelength of 1064 nanometers. The 1064 nm wavelength is harmful to human skin and eyes, especially if the eye accidentally touches a laser with a wavelength of 1064 nm, the damage to the eye may be permanent. Therefore, in foreign countries, the handheld laser rangefinder has completely banned the 1064 nm laser. In China, some manufacturers also have a laser rangefinder that produces 1064 nanometers.

For the 905nm and 1540nm laser rangefinders, we call it "safe." For the 1064 nm laser rangefinder, we call it "unsafe" because of its potential harm to the human body.

4. Precautions for Use of Laser Rangefinder DISTO and other hand-held laser range finders use laser for distance measurement, while pulsed laser beam is a monochromatic light source with very concentrated energy. Look straight ahead and do not use the telescope to observe the smooth reflective surface so as not to injure the human eye. Be sure to measure according to the safety instructions in the instrument manual. When measuring in the field, do not direct the emission port of the instrument to the sun so as not to burn the photosensor of the instrument.

The above uses the DISTO instrument as an example to briefly describe the measurement function of the instrument. The function keys of the handheld laser distance meter produced by different manufacturers have similarities and differences. However, as long as the user manual is read carefully, the handheld laser distance meter will be fully utilized in the housing construction. The role of area measurement and other precision engineering measurements.

5. The plane of the measuring object must be perpendicular to the ray. Normally, the full-reflection prism is required for precise distance measurement. The range finder used for house measurement is directly measured with a smooth wall reflection, mainly because the distance is relatively close to the signal reflected by the light. The intensity is big enough. As you can see, it must be vertical, otherwise the return signal is too weak to get the exact distance.

6. It is usually possible to measure the plane of the object as diffuse reflection. In practice, thin plastic plates are used as reflective surfaces to solve the serious problem of diffuse reflection.

7. Hand-held laser rangefinder Measurement of the use of housing in the measurement of housing has always been the work of the housing management department. It is a drawing directly used as a property right certificate and has legal validity. It not only directly faces the common people, but also directly affects the economic interests of the people. Therefore, the control of housing measurement errors is particularly important. According to past practice, using a tape measure or a steel tape measure for the construction area, the use of area measurement, although it can also meet the basic Requirement, however, in long-distance measurement, there is a large error in the measurement of high-elevation and difficult-to-reach measurements, and there are disadvantages such as labor intensity and complicated work. In today's rapid development of new and high technologies, such original, traditional measurement methods have been Obviously does not meet the fast and efficient requirements of today's information society. For this reason, after the introduction of two Leica handheld laser distance meters, after several months of practical use, it is generally considered that the instrument is particularly suitable for the measurement of buildings with complex building structures, mid-rises and long distances. Easy to use, accurate measurement data (three millimeters accuracy), improved work efficiency (non-contact measurement), completely abandoned a tape measure (or steel tape measure) method of measuring the housing, reduce the survey error, ensure the accuracy of the area measurement, The result of the calculation made the owner more convinced. Of course, this instrument also has areas that need to be improved. For example, under strong sunlight, long-distance target objects are difficult to see and need to use telescopes and other accessories. In addition, it is more laborious to calibrate the leveling bubble for each measurement and it is better to calibrate it automatically. In short, the instrument is still welcome by us.

8. The use of laser range finder in the case traffic police It is understood that the case traffic police can hold the "Lycra PLUS" laser range finder aiming at the target and press it lightly, the traffic accident scene data can be done. The laser range finder as an auxiliary equipment for traffic accident scene mapping system automatically inputs the on-site measurement data and related information into the portable computer through Bluetooth wireless communication, and uses computer high-speed data calculation and graphics processing functions to quickly and accurately map out a standardized and accurate traffic accident. The on-site ratio map and automatic on-site survey transcripts greatly increase the speed and accuracy of measurement. The laser range finder has the characteristics of small size, light weight, easy to carry and so on. The ranging range is 0.2 meters to 200 meters, and the measuring accuracy is plus or minus 1.5 millimeters.