Laser rangefinders, as the name suggests, use lasers as the main working
substance to work. At present, the working materials of rangefinders on the
market mainly include the following: semiconductor lasers with working
wavelengths of 905 nm and 1540 nm, and YAG lasers with working wavelengths of
1064 nm. The wavelength of 1064 nanometers is harmful to human skin and eyes,
especially if the eyes are accidentally exposed to the laser of 1064 nanometers,
the damage to the eyes may be serious.
Therefore, in foreign countries, the 1064-nanometer laser is completely banned in rangefinders. In China, some manufacturers also produce 1064-nanometer laser rangefinders. For the 905nm and 1540nm rangefinders, we call them "safe". For the 1064 nm rangefinder, we call it "unsafe" because of its potential harm to the human body.
Rangefinders generally use two methods to measure distance: the pulse method and the phase method. The process of pulse method ranging is as follows: the laser emitted by the range finder is reflected by the object to be measured and then received by the range finder, and the range finder records the time of the laser round trip at the same time.
Because the rangefinder is light in weight, small in size, simple in operation, fast and accurate, its error is only one fifth to several hundredths of other optical rangefinders. So its maintenance work is very simple, just follow the following methods:
1. Always check the appearance of the instrument and remove the dust, grease, mildew, etc. on the surface in time.
2. Use a soft dry cloth when cleaning the eyepiece, objective lens or laser emission window. It is strictly forbidden to scratch with hard objects, so as not to damage the optical performance.
3. It should be handled with care during use, and it is strictly forbidden to squeeze or drop it from a high place, so as not to damage the instrument.
The laser rangefinder uses laser to measure distance, and the pulse beam is a monochromatic light source with very concentrated energy, so when using it, do not look directly at the emission port, and do not use an aiming telescope to observe the reflective surface, so as not to hurt people's glasses .
Laser rangefinder pictures
The principle of laser rangefinder:
1. Using the principle of infrared ranging or laser ranging: The principle of ranging can basically be attributed to measuring the time required for light to travel to and from the target, and then calculate the distance D 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 the continuous wave, which is called a phase-measuring rangefinder. Of course, there are also pulsed rangefinders. It should be noted that the phase measurement does not measure the phase of the infrared or laser, but measures the phase of the signal modulated on the infrared or laser. The construction industry has a hand-held laser rangefinderfor house measurements that works the same way.
2. The plane of the object to be measured should be perpendicular to the light: Usually, precision ranging requires a total reflection prism, and the rangefinder used for house measurement is directly measured by reflection from a smooth wall, mainly because the distance is relatively close, and the light is reflected back. The signal strength is high 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. The plane of the object can be measured as diffuse reflection: it is usually possible. In practical projects, a thin plastic plate will be used as a reflective surface to solve the problem of serious diffuse reflection.