Laser rangefinder in the operation of the policy shot a very fine laser beam, by the photoelectric element to receive the policy reflected laser beam, the timer measured the time from the laser beam to receive, calculate the distance from the observer to the policy if the laser is continuously launched, the measuring distance can reach about 40 kilometers, and can work day and night. If the laser pulse is launched, the general must precision is low, but for distance measurement, can reach the good relative accuracy laser rangefinder light weight, small volume, short operation is fast and accurate, its error is only one 5 of other optical rangefinder to several per cent, have been widely used in topographic survey, field measurement, tanks, planes, ships and artillery range of policy, measure the clouds, the height of the aircraft, missiles and satellites, etc. It is an important technical device for the precision of high moving tanks, aircraft, ships and artillery. As the price of laser rangefinders continues to drop, the industry is gradually using laser rangefinders.
At home and abroad, a number of new micro rangefinder with the advantages of fast ranging, small volume and reliable function, which can be widely used in industrial measurement and control, mines, ports and other fields. What is the principle of infrared ranging or laser ranging? The principle of ranging can be reduced to measuring the time required by the light reciprocation policy, and then calculate the distance D through the light speed c=299792458m/s and atmospheric refraction coefficient n. Because it is difficult to measure time directly, the phase of continuous wave is usually measured, which is called phase measuring rangefinder.Of course, there is also a pulse rangefinder, the typical WILD di-3000 needs to pay attention to, measuring the phase is not to measure the infrared maybe laser phase, but measure the modulation in the infrared maybe laser above the signal phase. Construction work is a kind of hand-held laser range finder, is used for house, the operational principle of the same plane object to be tested is necessary and total reflection prism light vertical yao general precision ranging demand collaboration, and house measurement range finder, directly reflect on the metope of smooth measurement, first because the distance closer, reflected light signal strength is enough big.And this can know, is bound to the vertical, otherwise the return signal is too small will not be able to get the accurate distance if plane object to be tested as diffuse can also can generally, in the practical engineering can choose thin plastic sheet as a reflective surface to deal with diffuse severe problem. Ultrasonic ranging accuracy is lower, now rarely used.
This is the use of laser monochromaticity and coherence, strong directionality and other characteristics, in order to end high-precision measurement and detection, such as measuring length, distance, speed, Angle and so on.Laser ranging can be divided into pulse laser ranging and continuous wave phase laser ranging.Pulsed laser ranging principle similar to radar ranging, rangefinder emission laser signal to the policy, policy will be reflected back, because the speed of light is known, so just recorded optical signal under reciprocating time, with the speed of light (300000 km/s) multiplied by the reciprocating one half of time, is to measure the distance.Hand-held and portable rangefinders, now widely used, range from hundreds of metres to tens of kilometres and measure with a precision of about five metres.