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Stereo tube Scherenfernrohr - optical instrument, consisting of two periscopes connected together at the eyepieces and spread apart at the lenses, for observing distant objects with both eyes. The German army trumpet in a case (Scherenfernrohr mit Kasten), nicknamed "rabbit ears" by the troops, was intended to monitor enemy positions, target designation and determine distances. It found its main application at the command and observation posts of artillery and infantry. The optics was characterized by the relation
10x50, i.e. 10x magnification with 50mm objective lenses. Periscopic optical system
located in steel pipes about 37 cm long. To get a good stereo effect, necessary for exact definition distances, the pipes were moved apart approximately at an angle of 90 degrees. The design included adjusting screws for adjusting the optical system and aligning the rangefinder marks, a level, a rechargeable battery, a light bulb, and a tripod mount. The kit included yellow filters, a spare light bulb, covers for lenses and eyepieces, and other little things.
In the stowed position, the pipes were reduced to contact and the entire structure was placed in a special, often leather, case with dimensions: 44.5 cm - height, 17.5 cm - width and from 21.5 cm to 11 cm - depth (narrower at the base) . The stereo tube could be equipped with a tripod and some additional devices.
The movable joints of the German stereotube structure were lubricated with a cold-resistant grease designed for a temperature of -20 °C. The main surfaces were painted in olive-green tones, but in winter the pipes right on the front line could be repainted white (in 1942, on the Elbrus passes, the Germans painted white not only binoculars, rangefinders and skis, but even donkeys used to transport equipment) .
The main manufacturer of these instruments (and, perhaps, the only one) was Carl Zeiss Jena. The manufacturer's code, serial number was affixed to the case
(for example, 378986), army order code (for example, "H / 6400"), designation
lubricants (e.g. "KF") and some other markings on individual units (e.g.
"S.F.14. Z.Gi." - Scherenfernrohr 14 Zielen Gitter - telescopic marking
pipes).
Stereo tube mesh Scherenfernrohr 14 
GERMAN RANGEFINDER
Stereo telescopic rangefinder, had a base distance of 1 meter. Its interesting feature was a special tripod for the shoulders, which made it possible to carry out observations and measurements of the straight arm. The rangefinder itself and all its components were stored in an oblong metal box, and the parts of the tripod were stored in a small aluminum trapezoid case.
forms.
Rangefinder mod.34 (model 1934) standard army mechanical optical rangefinder.
Entfernungsmesser 34 - the rangefinder itself
Gestell mit Behaelter - tripod with case
Stuetzplatte - base plate
Traghuelle - transport case
Berichtigungslatte mit Behaelter Alignment rail with cover (this is the "adjustment plate")
Serves to determine the distance between the gun and the target, as well as any other distances on the ground or to air targets.
It is mainly used to determine distances for heavy mortars and heavy machine guns, if the distance to the target is more than 1000 meters, as well as in combination with other means of artillery guidance.
Design, device and appearance almost identical to its predecessor, the rangefinder mod. 1914 (Entfernungsmesser 14).
The length of the range finder is 70 cm. The measurement range is from 200 to 10,000 meters. Has a field of view of 62 meters at a distance of 1000 meters.
The rangefinder is very simple and easy to use, moreover, it has a relatively small error in determining the distance, for example:
at 4500 meters, theoretical error = +/- 131 meters, and practical = +/- 395 meters.
(For example, at the same time, the Soviet easel, very bulky and multi-piece stereoscopic rangefinder has only half the error.)
To find out the distance to one or another object, you just need to combine the visible image in the main window with the image in the small one.
The rangefinder also has two rollers for changing the range scale (they have different scale change rates). 
For the initial, rough "picking" on the object on the body of the rangefinder there is a special front sight and sight.
In addition, the rangefinder lenses, if necessary, and in the stowed position, are protected from contamination and mechanical damage by metal cylindrical plates. And the eyepiece is protected by a special cover on a spring fastener.
The rangefinder kit includes:
- the rangefinder itself with a shoulder strap
- carrying case for rangefinder
- a tripod stand for a rangefinder with a case for a belt and a base plate, for wearing around the neck.
-correction plate with cover
The entire kit was carried by one person, but as a rule, not all of it was always on the rangefinder (in German, Messmann [messman]).
Baltic State TechnicalUniversity "VOENMEH" them. D. F. Ustinova
Quantum Artillery RangefinderDAK-2M.
St. Petersburg2002
Point the included rangefinder at people,
Point the rangefinder at specularly reflective surfacesand on surfaces close in reflection to specular,
Point the rangefinder at the sun.
1. The purpose of the work.
The purpose of this work is to study the principles of operation of quantum rangefinder devices, as well as their main components and design features.
2. Introduction.
Along with radar, there are other methods for determining the coordinates of an object. So wide application in practice, optical locators have been obtained that allow determining all three coordinates of an object with high accuracy. The study of the use of optical locators as goniometric devices is beyond the scope of this work; in the future, only the determination of the range will be considered. Methods for determining the range using optoelectronic means can be divided into active, using probing signals, and passive. The latter include stereoscopic rangefinders and image-focusing rangefinders (e.g. dual image rangefinders).
Optical locators, which include this quantum range finder, are characterized by a very high resolution in range and angular coordinates, which is due to a decrease in wavelength by several orders of magnitude compared to radio range devices. In quantum (laser) rangefinders, increasing the operating frequencies allows you to expand the usable frequency band. This makes it possible to form very short (up to tens of nanoseconds) probing pulses. In practice, this makes it possible to obtain a range resolution of the order of 1 meter at a range of several kilometers.
Laser radiation has a high directivity, which simplifies the selection of objects that are approximately in the same angular direction, but at significantly different ranges, and allows you to eliminate the errors associated with this.
3. The purpose of the rangefinder.
Artillery quantum rangefinder DAK-2M with a target selection device is designed for:
range measurements to moving and stationary targets, local objects and shell explosions;
ground artillery fire adjustments;
conducting visual reconnaissance of the area;
measurements of horizontal and vertical angles goals;
topographic and geodetic binding of elements of artillery combat formations with the help of other topographic and geodetic devices.
The DAK-2M rangefinder can be included in the artillery fire control complex as a reconnaissance and surveillance device, and can also be interfaced with the complex's computing devices.
The range finder provides distance measurement to targets such as a tank, a car with a probability of reliable measurement of 0.9 (in the absence of foreign objects in the beam alignment).
4. Tactical and technical data.
Maximum measurable range for tank-car targets, m 9000
Pointing angle range:
range of vertical pointing angles ±4-50
range of horizontal pointing angles ±30
3. Measurement accuracy of target parameters:
number of targets recorded on the target counter indicator 3
maximum range measurement error, m<6
range resolution, m 3
measurement accuracy of angular coordinates in both planes ±00-01
4. Optical characteristics of the receiver channel:
entrance pupil diameter, mm 96
3" field of view
FEDERAL AGENCY FOR EDUCATION
State educational institution of higher professional education
MOSCOW STATE INSTITUTE OF RADIO ENGINEERING ELECTRONICS AND AUTOMATION (TECHNICAL UNIVERSITY)
COURSE WORK
by discipline
"Physical foundations of measurements"
Theme: Rangefinder
№ student group performer - ES-2-08
Surname of the I. O. of the performer - Prusakov A. A.
Surname and name of the head - Rusanov K. E.
Moscow 2010
Introduction ____________________________________________________________3
2. Types of rangefinders ______________________________________________5
3. Laser rangefinder _____________________________________________6
3.1. Physical basis of measurements and principle of operation _________________8
3.2 Design features and principle of operation. Types and application ____12
4. Optical rangefinder __________________________________________19
4.1. Physical bases of measurements and principle of operation ________________21
4.1.2 Fixed Angle Thread Distance Meter ____________________________23
4.1.3 Measuring the slope distance with a filament distance meter __________25
4.2 Design features and principle of operation ___________________________________27
5. Conclusion ____________________________________________________________29
6. Bibliographic list ______________________________________30
1. Introduction
Rangefinder- a device designed to determine the distance from the observer to the object. Used in geodesy, for focusing in photography, in sights of weapons, bombing systems, etc.
Geodesy- branch of production associated with measurements on the ground. It is an integral part of construction work. With the help of geodesy, projects of buildings and structures are transferred from paper to nature with millimeter accuracy, volumes of materials are calculated, and compliance with the geometric parameters of structures is monitored. It also finds application in mining for calculating blasting and rock volumes.
The main tasks of geodesy:
Among the many tasks of geodesy, one can single out “long-term tasks” and “tasks for the coming years”.
Long term tasks include:
determination of the figure, size and gravitational field of the Earth;
distribution of a single coordinate system to the territory of a separate state, continent and the whole Earth as a whole;
performing measurements on the surface of the earth;
depiction of land surface areas on topographic maps and plans;
study of global displacements of the earth's crust blocks.
Currently, the main tasks for the coming years in Russia are as follows:
creation of state and local cadastres: land real estate, water forest, urban, etc.;
topographic and geodetic support for the delimitation (definition) and demarcation (designation) of the state border of Russia;
development and implementation of standards in the field of digital mapping;
creation of digital and electronic maps and their data banks;
development of a concept and a state program for the widespread transition to satellite methods for autonomous determination of coordinates;
creation of a comprehensive national atlas of Russia and others.
Laser ranging is one of the first areas of practical application of lasers in foreign military equipment. The first experiments date back to 1961, and now laser range finders are used both in ground military equipment (artillery, such), and in aviation (range finders, altimeters, target designators), and in the navy. This technique has been combat tested in Vietnam and the Middle East. Currently, a number of rangefinders have been adopted by many armies of the world.
Rice. 2 - Laser sight-rangefinder. First used on T72A
2. Types of rangefinders
Rangefinder devices are divided into active and passive:
sound rangefinder
light rangefinder
laser rangefinder
rangefinders using an optical parallax rangefinder camera)
rangefinders that use object-to-pattern matching
active:
passive:
The principle of operation of active type rangefinders is to measure the time it takes for the signal sent by the rangefinder to travel the distance to the object and back. The speed of signal propagation (the speed of light or sound) is assumed to be known.
The measurement of distances with passive type rangefinders is based on determining the height h of an isosceles triangle ABC, for example, using the known side AB = l (base) and the opposite acute angle b (the so-called parallax angle). For small angles b (expressed in radians)
One of the quantities, l or b, is usually constant, and the other is variable (measured). On this basis, rangefinders with a constant angle and rangefinders with a constant base are distinguished.
3. Laser range finder
Laser range finder - a device for measuring distances using a laser beam.
It is widely used in engineering geodesy, topographic survey, military navigation, gastronomic research, and photography.
A laser rangefinder is a device consisting of a pulsed laser radiation detector. By measuring the time it takes the beam to travel to the reflector and back, and knowing the value of the speed of light, it is possible to calculate the distance between the laser and the reflecting object.
Fig.1 Modern models of laser rangefinders.
electromagnetic radiation to propagate at a constant speed makes it possible to determine the distance to the object. So, with the pulse method of ranging, the following ratio is used:
where L- the distance to the object, the speed of light in vacuum, the refractive index of the medium in which the radiation propagates, t is the time it takes for the impulse to reach the target and back.
Consideration of this relation shows that the potential accuracy of distance measurement is determined by the accuracy of measurement of the time of passage of the energy pulse to the object and back. It is clear that the shorter the pulse, the better.
3.1. Physical bases of measurements and principle of operation
The task of determining the distance between the range finder and the target is reduced to measuring the corresponding time interval between the probing signal and the signal, the reflection from the target. There are three methods for measuring range, depending on what kind of modulation of laser radiation is used in the rangefinder: pulse, phase or phase-pulse. The essence of the pulse method of ranging is that a probing pulse is sent to the object, which also starts a time counter in the rangefinder. When the pulse reflected by the object reaches the rangefinder, it stops the counter. According to the time interval, the distance to the object is automatically displayed in front of the operator. Let us estimate the accuracy of such a ranging method if it is known that the accuracy of measuring the time interval between the probing and reflected signals corresponds to 10 V -9 s. Since we can assume that the speed of light is 3 * 10 cm / s, we get an error in changing the distance of about 30 cm. Experts believe that this is quite enough to solve a number of practical problems.
With the phase ranging method, laser radiation is modulated according to a sinusoidal law. In this case, the radiation intensity varies within a significant range. Depending on the distance to the object, the phase of the signal that fell on the object changes. The signal reflected from the object will arrive at the receiving device also with a certain phase, depending on the distance. Let us estimate the error of a phase rangefinder suitable for field operation. Experts say that it is not difficult for the operator to determine the phase with an error of no more than one degree. If the modulation frequency of the laser radiation is 10 MHz, then the distance measurement error will be about 5 cm.
According to the principle of operation, rangefinders are divided into two main groups, geometric and physical types.
Fig.2 The principle of operation of the rangefinder
The first group consists of geometric rangefinders. The measurement of distances with a range finder of this type is based on determining the height h of an isosceles triangle ABC (Fig. 3), for example, using the known side AB = I (base) and the opposite acute angle. One of the quantities, I, is usually a constant, and the other is a variable (measured). On this basis, rangefinders with a constant angle and rangefinders with a constant base are distinguished. A fixed angle rangefinder is a telescope with two parallel filaments in the field of view, and a portable rail with equidistant divisions serves as the base. The distance to the base measured by the rangefinder is proportional to the number of divisions of the staff visible through the telescope between the threads. Many geodetic instruments (theodolites, levels, etc.) work according to this principle. The relative error of the filament rangefinder is 0.3-1%. More complex optical rangefinders with a fixed base are built on the principle of superimposing images of an object constructed by beams that have passed through various optical systems of the rangefinder. Alignment is performed using an optical compensator located in one of the optical systems, and the measurement result is read on a special scale. Monocular rangefinders with a base of 3-10 cm are widely used as photographic rangefinders. The error of optical rangefinders with a constant base is less than 0.1% of the measured distance.
The principle of operation of a physical type rangefinder is to measure the time it takes the signal sent by the rangefinder to travel the distance to an object and back. The ability of electromagnetic radiation to propagate at a constant speed makes it possible to determine the distance to an object. Distinguish pulse and phase methods of distance measurement.
With the pulse method, a probing pulse is sent to the object, which starts a time counter in the rangefinder. When the pulse reflected by the object returns to the rangefinder, it stops the counter. By the time interval (delay of the reflected pulse), using the built-in microprocessor, the distance to the object is determined:
where: L is the distance to the object, c is the speed of radiation propagation, t is the time it takes the pulse to reach the target and back.
Rice. 3 - The principle of operation of the geometric type rangefinder
AB - base, h - measured distance
With the phase method, the radiation is modulated according to a sinusoidal law using a modulator (an electro-optical crystal that changes its parameters under the influence of an electrical signal). The reflected radiation enters the photodetector, where the modulating signal is extracted. Depending on the distance to the object, the phase of the reflected signal changes relative to the phase of the signal in the modulator. By measuring the phase difference, the distance to the object is measured.
3.2 Design features and principle of operation. Types and application
The first XM-23 laser rangefinder was tested and adopted by the armies. It is designed for use in advanced observation posts of the ground forces. The radiation source in it is a ruby laser with an output power of 2.5 W and a pulse duration of 30 ns. Integrated circuits are widely used in the design of the rangefinder. The emitter, receiver and optical elements are mounted in a monoblock, which has scales for accurately reporting the azimuth and elevation angle of the target. The rangefinder is powered by a 24V nickel-cadmium battery that provides 100 range measurements without recharging. In another artillery rangefinder, also adopted by the armies, there is a device for simultaneously determining the range of up to four targets lying on the same straight line by successively strobing distances of 200,600,1000, 2000 and 3000m.
Interesting Swedish laser rangefinder. It is intended for use in fire control systems of onboard naval and coastal artillery. The design of the rangefinder is particularly durable, which allows it to be used in difficult conditions. The rangefinder can be paired, if necessary, with an image intensifier or a television sight. The operating mode of the rangefinder provides for either measurements every 2s. within 20s. and with a pause between a series of measurements for 20 s. or every 4s. for a long time. Digital range indicators work in such a way that when one of the indicators gives the last measured range, the other four previous distance measurements are stored in the memory of the other.
A very successful laser rangefinder is the LP-4. It has an optical-mechanical shutter as a Q-switch. The receiving part of the rangefinder is also the sight of the operator. The diameter of the input optical system is 70mm. The receiver is a portable photodiode, the sensitivity of which has a maximum value at a wavelength of 1.06 μm. The meter is equipped with a range strobing circuit, which operates according to the operator's setting from 200 to 3000 m. In the scheme of the optical sight, a protective filter is placed in front of the eyepiece to protect the operator's eye from the effects of his laser when receiving the reflected pulse. The emitter and receiver are mounted in one housing. The elevation angle of the target is determined within + 25 degrees. The battery provides 150 distance measurements without recharging, its weight is only 1 kg. The rangefinder has been tested and purchased in a number of countries such as - Canada, Sweden, Denmark, Italy, Australia. In addition, the British Ministry of Defense signed a contract for the supply of a modified LP-4 rangefinder weighing 4.4 kg to the British army.
Portable laser rangefinders are designed for infantry units and forward artillery observers. One of these rangefinders is made in the form of binoculars. The source of radiation and the receiver are mounted in a common housing, with a monocular optical sight of six times magnification, in the field of view of which there is a light panel of LEDs, well distinguishable both at night and during the day. The laser uses an yttrium aluminum garnet as a radiation source, with a Q-switch on lithium niobate. This provides a peak power of 1.5 MW. The receiving part uses a dual avalanche photodetector with a broadband low noise amplifier, which makes it possible to detect short pulses with a low power of only 10 V -9 W. False signals reflected from nearby objects that are in the barrel with the target are eliminated using a range gating circuit. The power source is a small-sized rechargeable battery that provides 250 measurements without recharging. The electronic units of the rangefinder are made on integrated and hybrid circuits, which made it possible to increase the mass of the rangefinder together with the power source to 2 kg.
The installation of laser rangefinders on tanks immediately interested foreign developers of military weapons. This is due to the fact that on a tank it is possible to introduce a rangefinder into the tank's fire control system, thereby increasing its combat qualities. For this, the AN / VVS-1 rangefinder was developed for the M60A tank. It did not differ in design from a laser artillery rangefinder on a ruby, however, in addition to issuing range data on a digital display in the tank's fire control system calculator. In this case, the range measurement can be performed both by the gunner and the tank commander. Rangefinder operation mode - 15 measurements per minute for one hour. Foreign press reports that a more advanced rangefinder, developed later, has range limits from 200 to 4700m. with an accuracy of + 10 m, and a computer connected to the tank's fire control system, where, together with other data, 9 more types of ammunition data are processed. This, according to the developers, makes it possible to hit the target with the first shot. The fire control system of a tank gun has an analog, considered earlier, as a rangefinder, but it includes seven more sensory sensors and an optical sight. The name of the Kobeld installation. The press reports that it provides a high probability of hitting the target, and despite the complexity of this installation, the ballistics mechanism switch to the position corresponding to the selected type of shot, and then press the laser rangefinder button. When firing at a moving target, the gunner additionally lowers the fire control interlock switch so that the signal from the turret traverse speed sensor when tracking the target goes behind the tachometer to the computing device, helping to generate a signal from the institution. The laser rangefinder, which is part of the Kobeld system, allows you to measure the range simultaneously to two targets located in the alignment. The system is fast-acting, which allows you to shoot in the shortest possible time.
An analysis of the graphs shows that the use of a system with a laser rangefinder and a computer provides a probability of hitting a target close to the calculated one. The graphs also show how much more likely it is to hit a moving target. If for stationary targets the probability of hitting when using a laser system compared to the probability of hitting when using a system with a stereo rangefinder does not make a big difference at a distance of about 1000m, and is felt only at a distance of 1500m or more, then for moving targets the gain is clear. It can be seen that the probability of hitting a moving target when using a laser system, compared with the probability of hitting when using a system with a stereo range finder already at a distance of 100 m, increases by more than 3.5 times, and at a distance of 2000 m., where the system with a stereo range finder becomes practically ineffective, laser the system provides a probability of defeat from the first shot of about 0.3.
In armies, in addition to artillery and tanks, laser rangefinders are used in systems where it is required to determine the range with high accuracy in a short period of time. So, in the press it was reported that an automatic system for tracking air targets and measuring the distance to them was developed. The system allows accurate measurement of azimuth, elevation and range. Data can be recorded on magnetic tape and processed on a computer. The system has a small size and weight and is placed on a mobile van. The system includes a laser operating in the infrared range. Infrared TV camera receiver, TV monitor, servo-wire tracking mirror, digital display and recorder. The neodymium glass laser device operates in Q-switched mode and emits energy at a wavelength of 1.06 µm. The radiation power is 1 MW per pulse with a duration of 25 ns and a pulse repetition rate of 100 Hz. The divergence of the laser beam is 10 mrad. Tracking channels use various types of photodetectors. The receiver uses a silicon LED. In the tracking channel - a grating consisting of four photodiodes, with the help of which a mismatch signal is generated when the target is shifted away from the axis of sight in azimuth and elevation. The signal from each receiver is fed to a video amplifier with a logarithmic response and a dynamic range of 60 dB. The minimum threshold signal at which the system monitors the target is 5 * 10V-8W. The target tracking mirror is driven in azimuth and elevation by servomotors. The tracking system allows you to determine the location of air targets at a distance of up to 19 km. while the accuracy of target tracking, determined experimentally, is 0.1 mrad. in azimuth and 0.2 mrad in elevation of the target. Distance measurement accuracy + 15 cm.
Laser rangefinders on ruby and neodymium glass provide distance measurement to stationary or slowly moving objects, since the pulse repetition rate is low. Not more than one hertz. If it is necessary to measure short distances, but with a higher frequency of measurement cycles, then phase rangefinders with a semiconductor laser emitter are used. As a rule, they use gallium arsenide as a source. Here is the characteristic of one of the rangefinders: the output power is 6.5 W per pulse, the duration of which is 0.2 μs, and the pulse repetition rate is 20 kHz. The laser beam divergence is 350*160 mrad i.e. resembles a petal. If necessary, the angular divergence of the beam can be reduced to 2 mrad. The receiver consists of an optical system, and the focal plane of which is a diaphragm that limits the field of view of the receiver to the desired size. Collimation is performed by a short focus lens located behind the diaphragm. The working wavelength is 0.902 microns, and the range is from 0 to 400m. The press reports that these characteristics have been significantly improved in later designs. So, for example, a laser rangefinder with a range of 1500m has already been developed. and distance measurement accuracy + 30m. This rangefinder has a repetition rate of 12.5 kHz with a pulse duration of 1 μs. Another rangefinder developed in the USA has a range of 30 to 6400m. The pulse power is 100W, and the pulse repetition rate is 1000 Hz.
Since several types of rangefinders are used, there has been a tendency to unify laser systems in the form of separate modules. This simplifies their assembly, as well as the replacement of individual modules during operation. According to experts, the modular design of the laser rangefinder provides maximum reliability and maintainability in the field.
The emitter module consists of a rod, a pump lamp, an illuminator, a high-voltage transformer, and resonator mirrors. quality modulator. As a radiation source, neodymium glass or aluminum-sodium garnet is usually used, which ensures the operation of the rangefinder without a cooling system. All these elements of the head are placed in a rigid cylindrical body. Precise machining of the seats on both ends of the cylindrical body of the head allows for quick replacement and installation without additional adjustment, which ensures ease of maintenance and repair. For the initial adjustment of the optical system, a reference mirror is used, mounted on a carefully machined surface of the head, perpendicular to the axis of the cylindrical body. A diffusion-type illuminator consists of two cylinders entering one into the other, between the walls of which there is a layer of magnesium oxide. The Q-switch is designed for continuous stable operation or pulsed with fast starts. the main data of the unified head are as follows: wavelength - 1.06 μm, pump energy - 25 J, output pulse energy - 0.2 J, pulse duration 25 ns, pulse repetition rate 0.33 Hz for 12 s, operation with a frequency of 1 Hz is allowed) , the divergence angle is 2 mrad. Due to the high sensitivity to internal noise, the photodiode, preamplifier and power supply are housed in the same housing with the most dense arrangement possible, and in some models it is all made in a single compact unit. This provides a sensitivity of the order of 5 * 10 in -8 watts.
The amplifier has a threshold circuit that is activated at the moment when the pulse reaches half of the maximum amplitude, which helps to improve the accuracy of the range finder, because it reduces the effect of fluctuations in the amplitude of the incoming pulse. The start and stop signals are generated by the same photodetector and follow the same path, which eliminates systematic ranging errors. The optical system consists of an afocal telescope to reduce the divergence of the laser beam and a focusing lens for the photodetector. Photodiodes have an active area diameter of 50, 100, and 200 µm. A significant reduction in size is facilitated by the fact that the receiving and transmitting optical systems are combined, and the central part is used to form the radiation of the transmitter, and the peripheral part is used to receive the signal reflected from the target.
4. Optical rangefinder
Optical rangefinders is a generalized name for a group of rangefinders with visual aiming at an object (target), the operation of which is based on the use of the laws of geometric (beam) optics. Optical rangefinders are common: with a constant angle and a remote base (for example, a filament rangefinder, which is supplied by many geodetic instruments - theodolites, levels, etc.); with a constant internal base - monocular (for example, a photographic rangefinder) and binocular (stereoscopic rangefinders).
Optical range finder (light range finder) - a device for measuring distances by the time it takes optical radiation (light) to travel the measured distance. An optical rangefinder contains a source of optical radiation, a device for controlling its parameters, a transmitting and receiving system, a photodetector and a device for measuring time intervals. The optical rangefinder is divided into pulse and phase, depending on the methods for determining the time it takes the radiation to travel the distance from the object and back.
Rice. 4 - Modern optical rangefinder
Fig. 5 - Optical rangefinder type "Seagull"
In rangefinders, it is not the length of the line itself that is measured, but some other value, relative to which the length of the line is a function.
As previously mentioned, 3 types of rangefinders are used in geodesy:
optical (rangefinders of geometric type),
electro-optical (light range finders),
radio engineering (radio rangefinders).
4.1. Physical bases of measurements and principle of operation
Rice. 6 Geometric scheme of optical rangefinders
Let it be required to find the distance AB. We place an optical rangefinder at point A, and a rail at point B perpendicular to the line AB.
Denote: l - segment of the rail GM,
φ - the angle at which this segment is visible from point A.
From triangle AGB we have:
D=1/2*ctg(φ/2) (4.1.1)
D = l * сtg(φ) (4.1.2)
Usually the angle φ is small (up to 1 o), and by applying the expansion of the function Ctgφ in a series, formula (4.1.1) can be reduced to the form (4.1.2). On the right side of these formulas, there are two arguments with respect to which the distance D is a function. If one of the arguments has a constant value, then to find the distance D it is enough to measure only one value. Depending on what value - φ or l - is taken constant, there are rangefinders with a constant angle and rangefinders with a constant basis.
In a rangefinder with a constant angle, the segment l is measured, and the angle φ is constant; it is called the diastimometric angle.
In rangefinders with a constant basis, the angle φ is measured, which is called the parallactic angle; the segment l has a constant known length and is called a basis.
4.1.2 Constant angle thread distance meter
In the grid of threads of telescopes, as a rule, there are two additional horizontal threads located on both sides of the center of the grid of threads at equal distances from it; these are rangefinder threads (Fig. 7).
Let's draw the path of rays passing through the rangefinder filaments in the Kepler tube with external focusing. The device is installed above point A; at point B there is a rail installed perpendicular to the sight line of the pipe. Find the distance between points A and B.
Rice. 7 - Rangefinder threads
Let's construct the course of rays from the points m and g of the range-finding threads. Rays from points m and g, going parallel to the optical axis, after refraction on the objective lens, will cross this axis at the front focus point F and fall into points M and G of the rail. The distance from point A to point B will be:
D = l/2 * Ctg(φ/2) + frev + d (4.1.2.1)
where d is the distance from the center of the lens to the axis of rotation of the theodolite;
f about - focal length of the lens;
l is the length of the segment MG on the rail.
Denote (f about + d) through c, and the value 1/2*Ctg φ/2 - through C, then
D = C * l + c. (4.1.2.2)
The constant C is called the rangefinder coefficient. From Dm "OF we have:
Ctg φ / 2 \u003d ОF / m "O; m" O \u003d p / 2 (4.1.2.3)
Ctg φ/2 = (fob*2)/p, (4.1.2.4)
where p is the distance between the rangefinding threads. Next we write:
C \u003d f about / p. (4.1.2.5)
The rangefinder coefficient is equal to the ratio of the focal length of the lens to the distance between the rangefinder filaments. Usually, the coefficient C is taken equal to 100, then Ctg φ / 2 = 200 and φ = 34.38 ". At C = 100 and fob = 200 mm, the distance between the threads is 2 mm.
4.1.3 Measuring the slope distance with a filament distance meter
Let the sight line of the pipe JK when measuring the distance AB has an angle of inclination ν, and the segment l is measured along the rail (Fig. 8). If the rail were installed perpendicular to the pipe sight line, then the slope distance would be:
D = l 0 * C + c (4.1.3.1)
l 0 = l*Cos ν (4.1.3.2)
D = C*l*Cosν + c. (4.1.3.3)
The horizontal distance of the line S is determined from Δ JKE:
S = D*Cosν (4.1.3.4)
S= C*l*Cos2v + c*Cosv. (4.1.3.5)
rice. 8 - Measuring the slant distance with a filament rangefinder
For the convenience of calculations, we take the second term equal to c*Cos2ν ; since the c value is small (about 30 cm), such a replacement will not introduce a noticeable error in the calculations. Then
S = (C * l + c) * Cos 2 ν (4.1.3.6)
S = D"* Cos2v (4.1.3.7)
Usually the value (C * l + c) is called the rangefinding distance. Let us denote the difference (D" - S) by ΔD and call it the correction for reduction to the horizon, then
S = D" – ∆D (4.1.3.8)
ΔD = D" * Sin 2 ν (4.1.3.9)
The angle ν is measured by the vertical circle of the theodolite; where the correction ΔD is not taken into account. The accuracy of measuring distances with a filament rangefinder is usually estimated by a relative error from 1/100 to 1/300.
In addition to the usual filament rangefinder, there are optical double-image rangefinders.
4.2 Design features and principle of operation
In a pulse light rangefinder, the source of radiation is most often a laser, the radiation of which is formed in the form of short pulses. To measure slowly changing distances, single pulses are used; for rapidly changing distances, a pulsed radiation mode is used. Solid-state lasers allow the repetition rate of radiation pulses up to 50-100 Hz, semiconductor - up to 104-105 Hz. The formation of short radiation pulses in solid-state lasers is carried out by mechanical, electro-optical or acousto-optical shutters or their combinations. Injection lasers are controlled by the injection current.
In phase light rangefinders, incandescent or gas-light lamps, LEDs and almost all types of lasers are used as light sources. An optical rangefinder with LEDs provides a range of up to 2-5 km, with gas lasers when working with optical reflectors on an object - up to 100 km, and with diffuse reflection from objects - up to 0.8 km; similarly, the Optical Rangefinder with Semiconductor Lasers provides a range of 15 and 0.3 km. In phase light-range radiation, it is modulated by interference, acousto-optical, and electro-optical modulators. Electro-optical modulators based on resonator and waveguide microwave structures are used in microwave phase optical rangefinders.
In pulse light range finders, photodiodes are usually used as a photodetector; in phase light range finders, photodetection is carried out by photomultipliers. The sensitivity of the photoreceiving path of an optical rangefinder can be increased by several orders of magnitude by using optical heterodyning. The operating range of such an optical rangefinder is limited by the coherence length) of the transmitting laser, while it is possible to register movements and vibrations of objects up to 0.2 km.
The measurement of time intervals is most often carried out by the counting-pulse method.
5. Conclusion
Rangefinder - is the best device for measuring distance over long distances. Now laser rangefinders are used in ground military equipment and in aviation and navy. A number of rangefinders have been adopted by many armies of the world. Also, the rangefinder has become an indispensable part of hunting, which makes it unique and very useful.
6. Bibliographic list
1. Gerasimov F.Ya., Govorukhin A.M. Brief topographic and geodetic dictionary-reference book, 1968; M Nedra
Elementary course of optics and rangefinders, Voenizdat, 1938, 136 p.
Military optical-mechanical devices, Oboronprom, 1940, 263 p.
4. Internet shop of optics. Principles of operation of a laser rangefinder. URL: http://www.optics4you.ru/article5.html
Electronic version of the textbook in the form of hypertext
in the discipline "Geodesy". URL: http://cheapset.od.ua/4_3_2.html range finder Abstract >> Geology
K and f + d = c , we get D = K n + c , where K is the coefficient rangefinder and c is a constant rangefinder. Rice. 8.4. Thread rangefinder: a) - a network of threads; b) - scheme for determining ... levels. Device technical levels. Depending on the devices applied...
Optical reconnaissance devices.
Electron-optical devices.
ARTILLERY QUANTUM RANGER
Artillery quantum rangefinder 1D11 with a target selection device is designed to measure the range to fixed and moving targets, local objects and shell explosions, correct ground artillery fire, maintain visual
reconnaissance of the area, measurement of vertical and horizontal angles of targets, topographic and geodetic binding of elements of artillery combat formations.
The range finder provides distance measurement to targets (tank, car, etc.) with a probability of reliable measurement of at least 0.9 (if they are confidently detected in the optical sight and in the absence of foreign objects in the beam alignment).
The rangefinder operates under the following climatic conditions: atmospheric pressure of at least 460 mm Hg. Art., relative humidity up to 98%, temperature ± 35 ° C. The main performance characteristics of 1D11
Increase. . . ................. 8.7 x
Line of sight. . . ................. 1-00(6°)
Periscopicity .............. 330 mm
Distance measurement accuracy. . ......... 5-10 m
Quantity of measurements of range without replacement of the rechargeable battery - at least 300
The rangefinder is ready for operation after turning on the general power supply - no more than 10 s
The 1D11 rangefinder kit includes a transceiver, an angle measuring platform, a tripod, a rechargeable battery, a cable, a single set of spare parts and accessories, and a stowage box.
The principle of operation of the rangefinder is based on measuring the time it takes for a light signal to travel to a target and back.
A powerful radiation pulse of short duration, generated by an optical quantum generator, is directed by a forming optical system to the target, the range to which must be measured. The radiation pulse reflected from the target, having passed the optical system, falls on the rangefinder photodetector. The moment of emission of the probing pulse and the moment of arrival
The reflection of the reflected pulse is recorded by the trigger unit and the photodetector, which generate electrical signals to start and stop the time interval meter.
The time interval meter measures the time interval between the fronts of the emitted and reflected pulses. The range to the target, proportional to this interval, is determined by the formula
D=st/2,
where With - speed of light in the atmosphere, m/s;
t- measured interval, s.
The measurement result in meters is displayed on a digital indicator entered in the field of view of the left eyepiece.
Preparing the rangefinder for operation includes installation, leveling, orientation and performance testing
The installation of the rangefinder is carried out in this order. They choose a place for observation, place the tripod (with one of the legs pointing towards observation) above the chosen point so that the tripod table is approximately horizontal. An angle measuring platform (API) is installed on the tripod table and securely fixed with a set screw.
After placing the tripod, a rough leveling is carried out on the ball level with an accuracy of half a division of the level scale by changing the length of the legs of the tripod.
Then, the transceiver is installed with the shank into the seat of the UIP (previously moving the handle of the UIP clamping device counterclockwise to the stop) and, turning the transceiver, ensure that the fixing stops of the shank enter the corresponding grooves of the clamping device, after which the handle of the UIP is turned clockwise until the transceiver is securely fastened. Hang up the battery
battery on a tripod or install it to the right of the tripod, taking into account the possibility of turning the transceiver connected by a cable to the battery. Connect the cable to the transceiver and the battery, having previously removed the plugs from the corresponding connectors.
Accurate leveling on a cylindrical level is carried out in this order. The worm removal handle is pulled down to the stop and the transceiver is turned in such a way that the axis of the cylindrical level is parallel to the straight line passing through the axes of the two UIP lifting screws. The level bubble is brought to the middle, while simultaneously rotating the UIP lifting screws in opposite directions. The transceiver is rotated by 90° and, by turning the third lifting screw, the level bubble is again brought to the middle, the leveling accuracy is checked by smoothly turning the transceiver by 180°, and the leveling is repeated if, when turning, the cylindrical level bubble moves away from the middle by more than half a division.
Checking the rangefinder performance includes monitoring the battery voltage, monitoring the functioning of the time interval meter (IVI) and checking the functioning of the rangefinder.
The battery voltage is monitored in this order. Turn on the POWER switch and press the CHECK button. eg. If the red indicator light (on the right) lights up in the field of view of the left eyepiece, the battery voltage is too low and the battery needs to be replaced.
The control of the functioning of the time interval meter is carried out on three calibration channels in the following order: set the STROBING switch to position 0, press the START button. the PURPOSE switch is sequentially set to position 1,
2, 3 and after each switching, press the CALIBRATION button when the red signal dot (on the left) lights up in the field of view of the left eyepiece.
When you press the CALIBRATION button, the indicator readings must be within the limits indicated in the table
After the checks, the PURPOSE switch is set to position 1.
The operation of the rangefinder is checked by a control measurement of the range to the target, the distance to which is within the scope of the rangefinder and is known in advance with an error of no more than 2 m. If the range is not known exactly, then the distance to the same target is measured three times.
The measurement results should not differ from the known value or differ from each other by a value not exceeding the error indicated in the form.
Before orienting the rangefinder, the eyepiece of the sight is set to sharpen the image. If necessary, install a sighting pole on the head of the transceiver and fix it with a screw.
Orientation of the rangefinder, as a rule, is carried out according to the directional angle of the orientation direction. The order of orientation is as follows: point the transceiver at a landmark, the directional angle for which is known, set it on the limb (on a black scale) and on the scale
accurate readings, a reading equal to the value of the directional angle to the landmark, clamp the screws for fixing the limb and the nut for fixing the scale of accurate readings,
Measurement of horizontal angles is carried out using the monocular grid (up to 0-70), the limb scale (as the difference between the readings on the right and left points), the limb scale with the initial setting of 0 to the right point and subsequent marking on the left point. Vertical angles are measured using the monocular reticle (up to 0-35) and the target elevation angle mechanism scale.
Range measurement with a 1D11 rangefinder is carried out as follows.
Looking through the right eyepiece and turning the handwheels of the horizontal and vertical aiming mechanisms, point the reticle mark at the target, turn on the POWER switch, press the START button and after the signal dot lights up, press the MEASUREMENT button without knocking down the aiming. After that, the reading of the measured range and the number of targets in the beam alignment are taken in the left eyepiece.
If the MEASUREMENT button has not been pressed within 65-90 s. from the moment the readiness indicator lights up, the rangefinder automatically turns off. The measured range is displayed in the left eyepiece for 5-9 s.
If there are several targets (up to three) in the beam alignment, the rangefinder, at his choice, can measure the range to any of them. The rangefinder measures the distance to the first target when the TARGET switch is set to position 1. To measure the range to the second or third target, the TARGET switch is set to position 2 or 3, respectively. In addition, the rangefinder provides stepwise distance gating in range. The rangefinder by setting the STROBING switch to positions 0, 0, 4, 1, 2 and 3 can start measuring the range from distances of 200, 400, 1000, 2000 and 3000 m from the rangefinder, respectively.
After ten such measurements, a three-minute break must be taken.
The reliability of the measurement results depends on the correct choice of the aiming point on the object, since the power of the reflected beam depends on the effective reflection area of the target and its reflection coefficient. Therefore, when measuring, you need to choose a point in the center of the visible area.
If it is impossible to measure the distance directly to the target, the distance to a local object located in the immediate vicinity of the target is measured.
To transfer the rangefinder from the combat position to the marching position, turn off the POWER and LIGHT switch, record the readings of the impulse counter, disconnect the power cable first from the battery, and then from the transceiver and put it in the pocket of the packing box. Remove the sighting pole, lantern from the transceiver and place them in the packing box. Close the plugs and the socket for the pole with plugs. Pull the handle of the UIP clamping device counterclockwise until it stops. Remove the transceiver from the UIP, put it in the packing box and fix it in it. Place the battery in the storage box. Remove the UIP from the tripod, put it in the packing box and fix it in it. Fold the tripod, cleaning it of dirt, and fix it on the stacking box.
A variety of quantum rangefinders is laser reconnaissance device(LPR). A laser reconnaissance device in relation to an artillery quantum rangefinder has a number of advantages: dimensions and weight are smaller, more power sources, the ability to work "by hand". At the same time, the main tactical and technical characteristics of the APR are worse compared to the DAK, during combat work its stability is significantly lower, the device does not have a periscope. In addition, its active measuring channel is subject to flare from a bright light source.
Safety requirements when working with the LPR, the procedure and rules for orienting the device according to the directional angle or compass, checking its performance do not differ from similar actions with the DAC.
The device can be powered by a built-in battery, an on-board network of wheeled or tracked vehicles, or non-standard batteries. In this case, when operating from other sources (except for the built-in battery), a protective device is installed instead of the built-in battery.
The transition conductor is connected to a current source, observing the polarity.
To transfer the decision maker to a combat position:
to work "by hand" remove the device from the case, connect the selected (or existing) power source, check the operation of the device;
to work with a tripod from the kit, set the tripod in the chosen place according to the general rules (it is possible to fix the tripod cup in any wooden object);
install the angle measuring device (UIU) with a ball bearing in the cup; insert the ICD clamp into the T - shaped groove of the device bracket until it stops and fix the device by turning the handle of the clamping device;
to work with a periscope artillery compass, a compass is installed for work, leveled and oriented; mounted on the monocular compass transition crowns
matte: insert the clamp of the bracket into the T - shaped groove of the bracket of the device until it stops and fix the device.
In the stowed position, the LPR is transferred in the reverse order.
To measure the range, press the MEASUREMENT-1 button, after the ready indicator lights up, the button is released and the range indicator is read.
The rangefinder is aimed at the target so that it covers the largest possible area of the grid gap. If more than one target hits the radiation target, then the distance to the second deli is measured by pressing the MEASUREMENT-2 button.
The measured value is displayed in the range indicator for 3-5 s.
Horizontal and vertical angles are measured according to the rules common for goniometers. Angles not exceeding 0-80 div. ang., can be estimated from the goniometric grid with an accuracy of no higher than 0-05 div. ang.
To determine the polar coordinates of the target, the distance to it is measured and the azimuth reading is taken. Rectangular coordinates are determined using the coordinate converter included in the kit, or by any other known method.
When working in conditions of strong background noise (the target is located against the backdrop of a bright sky or surfaces lit by a bright sun, etc.), the diaphragm stored in the case cover is inserted into the lens barrel. At negative temperatures from -30°C and below, the diaphragm is not installed.
When measuring the distance to remote, small-sized or moving targets, for convenience, a cable of remote buttons is connected to the plug on the rangefinder panel.
A detailed description of the device kit, the procedure for combat work and maintenance of the device are given in the Calculation Memo attached to each kit.
