what is the laser distance meter?
laser distance measuring as a light source is a laser ranging. Depending on how the work is divided into laser continuous laser and pulsed lasers. Helium-neon, argon ion, krypton gases such as cadmium laser operating in continuous output state for phase-shift laser rangefinder; gallium arsenide double heterostructure semiconductor laser for infrared range; ruby, neodymium glass and other solid-state lasers for pulsed laser ranging. Since the laser monochrome laser rangefinder good, strong directional characteristics, plus electronic circuits of the semiconductor integrated, compared with EDM, not only can work day and night, but also improve the range accuracy, significantly reduced weight and power consumption, making measurements to artificial earth satellites, lunar and other targets far from the reality.
Baidu Encyclopedia: laser distance meter
Laser distance meter is the use of a laser to target distance accurate measurement instrument. In operation laser rangefinder to the target emit a very fine laser, received by the photoelectric element of the laser beam reflected by the target, a timer measuring the time the laser beam emitted from the receiver, calculates the distance from the observer to the target.
If the laser is a continuous emission, measurement range up to 40 kilometers, and can carry out day and night operations. If the laser pulse is emitted, generally low absolute accuracy, but for distance measurement, can achieve a good relative accuracy.The world's first laser, by US scientists Maiman of Hughes Aircraft Company in 1960, the first successful development. The US military quickly on the basis of carried out research on military laser device. In 1961, the first with a laser rangefinder demonstration test by the US military, this laser distance meter quickly into the practical Commonwealth.
Laser distance meter light weight, small size, simple operation, fast and accurate, the error is only one fifth of a percent to several other optical rangefinder, which is widely used for topographic survey, battlefield measure, tanks , aircraft, warships and artillery against targets ranging, measuring cloud height, aircraft, missiles and satellites and so on. It is to improve high tanks, aircraft, warships and artillery accuracy of important technical equipment.
Since the laser distance meter prices continue to drop, the industry has gradually started using a laser range finder. Domestic and abroad there has been a number of new micro-ranging rangefinder has a fast, small, reliable performance advantages can be widely used in industrial measurement and control, mining, ports and other areas.
Laser sixties developed a new technology. It is a very pure color, high concentration of energy, good directional light. Laser distance meter is an instrument by laser ranging. Its function principle is simple: start by determining the laser emitting laser light reflected from the target to the time to measure the distance. For example, a laser range finder to measure the distance of the moon, if the laser light emitted from the beginning to the time reflected from the moon was determined to be 2.56 seconds, the laser emission to the moon one-way time is equal to 1.28 seconds, and the speed of the laser light is the speed of light, equal three hundred thousand kilometers per second. Thus, the measured distance of the moon from the earth is the product of one-way speed of light and time, that is the three hundred and eighty-four thousand kilometers. In order to transmit and receive the laser, and for a time, by a laser rangefinder laser transmitter, a receiver, a clock oscillator frequency and distance counter and other components.
Laser distance meter can be used to track satellites ranging measure aircraft flight altitude, distance to the target to aim, as well as terrain mapping, prospecting and so 。
Diffuse laser distance meter to resolve the problem
Usually in order to reduce errors, those laser rangefinder will be measured on a reflecting surface to reduce errors caused by diffuse reflection, that those laser rangefinder telescopic sniper in the end is how to overcome this problem? Laser distance meter and sonar works the same, but received reflected light signal will not easily be interference from other light wavelength and intensity of the environment?
Laser distance meter (pulse) detection devices typically use avalanche photodiode, then it is only a very small light intensity of a specific wavelength of light sensitive, it can also be matched wavelength is detected, the wavelength does not match, even if the light intensity greatly and it can not be detected. Just having a good monochrome laser characteristics common wavelength of 905nm. Therefore, the signal light receiving reflected light interference environment is not likely to be other wavelength and intensity.
There are two commonly used laser ranging program: pulse method and phase method.Phase method by measuring the return phase shift waves to measure the distance, the need to meet the target, which is a reflective surface on what you said measured . in this case, the transmission power of smaller rangefinder.
Snipers with telescopic laser rangefinders are generally used in pulse method, which sends a pulse, start time, after receiving the reflected pulse stop the clock, to achieve the purpose of distance. When such a case, there is no cooperation objectives, by diffuse light energy losses are very serious, but generally do not affect the measurement. As previously mentioned reasons. Usually rangefinder will increase transmit power to make some compensation.
Hand-held laser distance meter work
If the laser is a continuous emission, measurement range up to 40 kilometers, lined butterfly valves can be day and night operations. If the laser pulse is emitted, generally low absolute accuracy, but for the amount of distance, you can achieve a good relative accuracy. The world's first laser, by US scientists Maiman of Hughes Aircraft Company in 1960, the first successful development. The US military quickly on the basis of carried out research on military laser device. In 1961, Taiwan's first with a laser rangefinder demonstration test by the US military, this laser rangefinder quickly into the practical Commonwealth. Laser rangefinder light weight, small size, simple operation, fast and accurate, the error is only one fifth of a percent to several other optical rangefinder, which is widely used for topographic survey, battlefield measure, tanks , aircraft, warships and artillery against targets ranging, measuring cloud height, aircraft, missiles and satellites and so on. It is to improve high tanks, aircraft, warships and artillery accuracy of important technical equipment. Since the laser range finder prices continue to drop, the industry has gradually started using a laser range finder. At home and abroad there has been a number of new micro-ranging rangefinder has a fast, small, reliable performance advantages can be widely used in industrial measurement and control, mining, ports and other areas. Main Category 1D laser rangefinder for distance measurement, positioning; 2D Scanning Laser Rangefinder is used to measure the contour, location, area monitoring and other areas; three-dimensional 3D Laser Rangefinder for three-dimensional profile measurement, three-dimensional spatial orientation, and other fields).
The measuring principle and method of using a laser to measure the distance from Earth to the moon is a schematic diagram of a laser rangefinder
1. What is the use of infrared ranging or laser ranging principle? Ranging principle which can be attributed to the measurement light and from the target required time, and then the speed of light c = 299792458m / s and atmospheric refractive index n calculates the distance D. Because of direct measurement is difficult, usually the measuring continuous wave phase, called test-phase rangefinder. Of course, there are also pulse rangefinder, typically WILD's DI-3000 should be noted, is not measured with infrared or laser phase measurement, but the measurement of phase modulation signal in the infrared or laser above. Construction industry there is a hand-held laser range finder for measuring housing, it works the same way.
2. The measured object must be perpendicular to the plane of the light? Usually requires precise distance measurement with total reflection prism, the Housing measured by the rangefinder, directly to the smooth wall reflection measurements, mainly because of the relatively close distance, the light intensity of the reflected signal is large enough. You can know this must be vertical, otherwise there will be no return signal is too weak,Method to obtain the exact distance.)
3. If the object plane of diffuse reflection? Usually possible, the actual project will use thin plastic plate as the reflective surface to solve the serious problem of diffuse reflection.
4.The ultrasonic distance measurement accuracy is relatively low, it is now rarely used.