A Scherenfernrohr stereo tube is an optical device consisting of two periscopes, connected together at the eyepieces and spread apart at the lenses, for observing distant objects with two eyes. The German army trumpet in a case (Scherenfernrohr mit Kasten), nicknamed “rabbit ears” by the troops, was intended for observing enemy positions, target designation and determining distances. It was mainly used at command and observation posts of artillery and infantry. The optics were characterized by the ratio
10x50, i.e. 10x magnification with 50mm objective lenses. Periscope optical system
was located in steel pipes about 37 cm long. To obtain a good stereo effect necessary for precise definition distances, the pipes were moved apart at approximately an angle of 90 degrees. The design included adjusting screws for adjusting the optical system and aligning rangefinder marks, a level, a battery, a light bulb, and a mounting unit for a tripod. The kit included yellow filters, a spare light bulb, covers for lenses and eyepieces and other small items.

In the stowed position, the pipes were brought together until they touched 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 accessories.
The moving joints of the German stereo tube structure were lubricated with a cold-resistant lubricant designed for a temperature of -20 °C. The main surfaces were painted in olive green tones, but in winter the pipes right at the front line could be repainted white (in 1942, on the passes of the Elbrus region, the Germans painted white not only binoculars, rangefinders and skis, but even donkeys used for transporting equipment) .
The main manufacturer of these instruments (and perhaps the only one) was the Carl Zeiss Jena company. The manufacturer's code and serial number were stamped on the case
(for example, 378986), army order code (for example, "H/6400"), designation
lubricants (for example, “KF”) and some other markings on individual components (for example,
“S.F.14. Z.Gi." — Scherenfernrohr 14 Zielen Gitter — telescopic marking
pipes).

Stereo tube mesh Scherenfernrohr 14

GERMAN RANGE FINDER

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. straight hand. The rangefinder itself and all its components were stored in an oblong metal box, and the tripod parts were stored in a small aluminum trapezoidal case.
forms.

Rangefinder mod.34 (model 1934) standard army mechanical optical rangefinder.
Entfernungsmesser 34 - the rangefinder itself
Gestell mit Behaelter - tripod with cover
Stuetzplatte - base plate
Traghuelle - transport case
Berichtigungslatte mit Behaelter alignment rod with cover (this is the “adjustment plate”)
Serves to determine the weapon-target distance, as well as any other distances on the ground or to air targets.
It is used mainly 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 artillery guidance means.

Design, device and appearance almost identical to its predecessor, the rangefinder mod. 1914 (Entfernungsmesser 14).
The length of the rangefinder 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, despite the fact that it has a relatively small error in determining the distance, for example:
at 4500 meters the theoretical error = +/- 131 meters, and the practical error = +/- 395 meters.
(For example, from the same time, the Soviet easel, very bulky and multi-component stereoscopic rangefinder has only half the error.)
To find out the distance to a particular object, you simply need to combine the visible picture in the main window with the picture in the small one.
The rangefinder also has two rollers for changing the range scale (they have different speeds for changing the scale).

For initial, rough “aiming” at an object, there is a special front sight and sight on the rangefinder body.
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 with 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 belt cover and a base plate, for wearing around the neck.
-adjustment plate with cover
The entire set was carried by one person, but as a rule, not all of it was always on the rangefinder (in German Messmann [messman]).

FEDERAL EDUCATION AGENCY

State educational institution of higher professional education

MOSCOW STATE INSTITUTE OF RADIO ENGINEERING ELECTRONICS AND AUTOMATION (TECHNICAL UNIVERSITY)

COURSE WORK

by discipline

"Physical basis of measurements"

Topic: Rangefinder

No. of student group performer – ES-2-08

Last name of the acting performer is A. A. Prusakov.

Last name of the acting director is K.E. Rusanov.

Moscow 2010

Introduction ______________________________________________________________3

2. Types of rangefinders _____________________________________________5

3. Laser rangefinder _____________________________________________6

3.1. Physical Basics measurements and operating principle _________________8

3.2 Design features and operating principle. Types and applications ____12

4. Optical rangefinder __________________________________________19

4.1. Physical basis of measurements and principle of operation ________________21

4.1.2 Filament rangefinder with constant angle _________________________________23

4.1.3 Measuring slant distance with a thread rangefinder __________25

4.2 Design features and operating principle ______________________________27

5. Conclusion ______________________________________________________________29

6. Bibliography _____________________________________________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 sighting devices for weapons, bombing systems, etc.

Geodesy- a branch of production associated with on-site measurements. It is an integral part of construction work. With the help of geodesy, designs of buildings and structures are transferred from paper to nature with millimeter precision, volumes of materials are calculated, and compliance with the geometric parameters of structures is monitored. It is also used in mining for calculating blasting operations and rock volumes.

The main tasks of geodesy:

Among the many tasks of geodesy, one can distinguish “long-term tasks” and “tasks for the coming years.”

Long-term objectives include:

determination of the shape, size and gravitational field of the Earth;

spreading unified system coordinates to the territory of a particular state, continent and the entire Earth as a whole;

performing measurements on the earth's surface;

depiction of areas of the earth's surface on topographic maps and plans;

study of global displacements of blocks of the earth's crust.

Currently, the main tasks for the coming years in Russia are the following:

creation of state and local cadastres: land real estate, water forest, urban, etc.;

topographic and geodetic support for 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 state program for the widespread transition to satellite methods of autonomous position determination;

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 rangefinders are used in ground-based military equipment (artillery, such), and in aviation (rangefinders, altimeters, target designators), and in the navy. This equipment has been combat tested in Vietnam and the Middle East. Currently, a number of rangefinders have been adopted by many armies around the world.

Rice. 2 - Laser sight-rangefinder. First used on T72A

2. Types of rangefinders

Rangefinder devices are divided into active and passive:

active:

• sound rangefinder

  light rangefinder

  laser rangefinder

passive:

• rangefinders using optical parallax (rangefinder camera)

  rangefinders that use object-to-pattern matching

The operating principle of active type rangefinders is to measure the time it takes for the signal sent by the rangefinder to travel the distance to an object and back. The speed of signal propagation (the speed of light or sound) is considered known.

Measuring distances with passive type rangefinders is based on determining the height h of the isosceles triangle ABC, for example by known party AB = l (base) and the opposite acute angle b (the so-called parallactic angle). For small angles b (expressed in radians)

One of the quantities, l or b, is usually a constant, and the other is a variable (measurable). Based on this feature, a distinction is made between rangefinders with a constant angle and rangefinders with a constant base.

3. Laser rangefinder

Laser rangefinder is a device for measuring distances using a laser beam.

Widely used in engineering geodesy, topographical surveying, military navigation, astronomical 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 speed of light, you can calculate the distance between the laser and the reflecting object.

Fig.1 Modern models of laser rangefinders.

electromagnetic radiation propagating at a constant speed makes it possible to determine the distance to an object. Thus, with the pulse ranging method, the following relationship is used:

Where L- the distance to the object, the speed of light in a vacuum, the refractive index of the medium in which the radiation propagates, t- the time it takes for the impulse to travel to the target and back.

Consideration of this relationship shows that the potential accuracy of range measurement is determined by the accuracy of measuring the time it takes for the energy pulse to travel to the object and back. It is clear that the shorter the impulse, the better.

3.1. Physical basis of measurements and principle of operation

The task of determining the distance between the rangefinder and the target comes down to measuring the corresponding time interval between the probing signal and the signal reflected from the target. There are three methods for measuring range depending on the type of modulation of laser radiation used in the rangefinder: pulse, phase or pulse-phase. The essence of the pulse ranging method is that a probing pulse is sent to the object, which also starts a time counter in the range finder. When the impulse reflected by the object reaches the rangefinder, it stops the counter. Based on the time interval, the distance to the object is automatically displayed in front of the operator. Let us evaluate the accuracy of this ranging method if it is known that the accuracy of measuring the time interval between the probing and reflected signals corresponds to 10 in -9 s. Since we can assume that the speed of light is 3 * 10 x 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 significant limits. Depending on the distance to the object, the phase of the signal incident on the object changes. The signal reflected from the object will also arrive at the receiving device with a certain phase, depending on the distance. Let us estimate the error of a phase rangefinder suitable for working in field conditions. 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 error in measuring the distance will be about 5 cm.

Based on the principle of operation, rangefinders are divided into two main groups, geometric and physical types.

Fig.2 Operating principle of the rangefinder

The first group consists of geometric rangefinders. Measuring distances with a rangefinder of this type is based on determining the height h of the 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 (measurable). Based on this feature, a distinction is made between rangefinders with a constant angle and rangefinders with a constant base. A constant-angle rangefinder is a telescope with two parallel threads in the field of view, and the base is a portable staff with equidistant divisions. The distance to the base measured by the rangefinder is proportional to the number of staff divisions visible through the telescope between the threads. Many geodetic instruments (theodolites, levels, etc.) work on this principle. The relative error of the filament rangefinder is 0.3-1%. More complex optical rangefinders with a constant base are built on the principle of combining images of an object constructed by beams that have passed through various optical rangefinder systems. The alignment is carried out 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 for 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. There are pulse and phase methods of range measurement.

With the pulse method, a probing pulse is sent to the object, which triggers a time counter in the rangefinder. When the pulse reflected by the object returns to the rangefinder, it stops the counter. Based on 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 for the pulse to travel to the target and back.

Rice. 3 - Operating principle of a 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 released. 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 operating principle. Types and applications

The first laser rangefinder XM-23 was tested and was adopted by the armies. It is designed for use in forward observation posts of 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 rangefinders. 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 24V nickel-cadmium batteries, which provide 100 range measurements without recharging. Another artillery rangefinder, also adopted by armies, has a device for simultaneously determining the range of up to four targets lying on the same straight line, by sequentially gating distances of 200,600,1000, 2000 and 3000m.

The Swedish laser rangefinder is interesting. It is intended for use in fire control systems for onboard naval and coastal artillery. The design of the rangefinder is particularly robust, which allows it to be used in folded conditions. The rangefinder can be interfaced, if necessary, with an image intensifier or television sight. The rangefinder operating mode provides either measurements every 2s. within 20s. and with a pause between a series of measurements for 20 s. or every 4s. During a long time. Digital range indicators work in such a way that when one of the indicators displays the last measured distance, the other four previous distance measurements are stored in the memory.

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 operator's sight. The diameter of the input optical system is 70mm. The receiver is a portable photodiode, the sensitivity of which is maximum value at a wavelength of 1.06 microns. The meter is equipped with a range gating circuit that operates at the operator's discretion from 200 to 3000 m. In the optical viewfinder circuit, a protective filter is placed in front of the eyepiece to protect the operator’s eye from the effects of its laser when receiving a reflected pulse. The emitter and receiver are mounted in one housing. The target elevation angle is determined within + 25 degrees. The battery provides 150 range 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 entered into 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 designed in the form of binoculars. The radiation source and 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 display of LEDs, clearly visible both at night and during the day. The laser uses yttrium aluminum garnet as a radiation source, with a lithium niobate Q switch. 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 low power of only 10 V -9 W. False signals reflected from nearby objects located in the target barrel 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 weight of the rangefinder together with the power source to 2 kg.

The installation of laser rangefinders on tanks immediately attracted the interest of foreign military weapon developers. This is explained by 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 purpose, the AN/VVS-1 rangefinder was developed for the M60A tank. It did not differ in design from the laser artillery rangefinder on the ruby, but in addition to issuing range data on a digital display in the counting device of the tank's fire control system. In this case, range measurement can be carried out both by the gunner and the tank commander. The rangefinder operating mode is 15 measurements per minute for one hour. Foreign press reports that a more advanced rangefinder, developed later, has range measurement limits from 200 to 4700m. with an accuracy of + 10 m, and a computing device connected to the tank’s fire control system, where 9 more types of ammunition data are processed together with other data. 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 the analogue discussed earlier as a range finder, but it includes seven more sensors and an optical sight. Name of Kobeld's installation. The press reports that it provides a high probability of hitting the target and despite the complexity of this installation, switch the ballistics mechanism 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 locking 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 the establishment signal. The laser rangefinder included in the Kobeld system allows you to measure the range simultaneously of up to two targets located on target. The system is fast-acting, allowing you to fire a shot in the shortest possible time.

Analysis of the graphs shows that the use of a system with a laser range finder and a computer provides a probability of hitting a target close to the calculated one. The graphs also show how much the probability of hitting a moving target increases. If for stationary targets the probability of being hit when using laser system Compared to the probability of defeat when using a system with a stereo rangefinder, it 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 to the probability of hitting 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 a 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 necessary to determine the range with high accuracy in a short period of time. Thus, it was reported in the press that an automatic system for tracking air targets and measuring their range has been developed. The system allows for accurate measurement of azimuth, elevation and range. Data can be recorded on magnetic tape and processed on a computer. The system is small in size and weight and is placed on a mobile van. The system includes a laser operating in the infrared range. Receiving device with infrared television camera, television control device, tracking mirror with servo wire, digital indicator and recording device. The neodymium glass laser device operates in Q-switched mode and emits energy at a wavelength of 1.06 microns. 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. Support channels use Various types photodetectors. The receiving device uses a silicon LED. In the tracking channel there is an array consisting of four photodiodes, with the help of which a mismatch signal is generated when the target moves away from the sighting axis 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 tracks 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. in this case, the accuracy of target tracking, determined experimentally, is 0.1 mrad. in azimuth and 0.2 mrad in target elevation. Range measurement accuracy + 15 cm.

Ruby and neodymium glass laser rangefinders provide distance measurements to stationary or slowly moving objects, since the pulse repetition rate is low. No more than one hertz. If you need to measure short distances, but with a higher frequency of measurement cycles, then use phase rangefinders with a semiconductor laser emitter. They usually use gallium arsenide as a source. Here is the characteristic of one of the rangefinders: 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 receiving device consists of an optical system, and on the focal plane of which there is a diaphragm that limits the field of view of the receiver to the required size. Collimation is performed by a short-focus lens located behind the diaphragm. The operating wavelength is 0.902 microns, and the range is from 0 to 400m. The press reports that these characteristics were significantly improved in later designs. 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 measuring range from 30 to 6400m. The pulse power is 100 W, and the pulse repetition rate is 1000 Hz.

Since several types of rangefinders are used, there is 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 field conditions.

The emitter module consists of a rod, a pump lamp, an illuminator, a high-voltage transformer, and resonator mirrors. Q modulator. The radiation source is usually neodymium glass or sodium aluminum garnet, which ensures the rangefinder operates without a cooling system. All these head elements are housed in a rigid cylindrical body. Precision machining of the seats at both ends of the cylindrical head body allows for their quick replacement and installation without additional adjustment, and this ensures ease of maintenance and repair. For initial adjustment of the optical system, a reference mirror is used, mounted on a carefully processed surface of the head, perpendicular to the axis of the cylindrical body. A diffusion-type illuminator consists of two cylinders that fit into each other, between the walls of which there is a layer of magnesium oxide. The Q modulator is designed for continuous stable operation or pulsed operation with quick 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 frequency 0.33 Hz for 12 s, operation at a frequency of 1 Hz is allowed) , divergence angle 2 mrad. Due to the high sensitivity to internal noise, the photodiode, preamplifier and power supply are placed in one package as densely as possible, and in some models all this is made in the form of a single compact unit. This provides a sensitivity of the order of 5 * 10 V -8 W.

The amplifier has a threshold circuit that is excited at the moment when the pulse reaches half the maximum amplitude, which helps to increase the accuracy of the rangefinder, because it reduces the influence 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 active pad diameters of 50, 100, and 200 microns. A significant reduction in size is facilitated by the fact that the receiving and transmitting optical systems are combined, with the central part used to generate the transmitter radiation, and the peripheral part to receive the signal reflected from the target.

4. Optical rangefinder

Optical rangefinders are a generalized name for a group of rangefinders with visual guidance on 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 remote base (for example, a thread rangefinder, which is supplied with many geodetic instruments - theodolites, levels, etc.); with a constant internal base - monocular (for example, photographic rangefinder) and binocular (stereoscopic rangefinder).

Optical range finder (light range finder) is a device for measuring distances based on 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, transmitting and receiving systems, a photoreceiving device and a device for measuring time intervals. Optical rangefinders are divided into pulse and phase, depending on the methods for determining the time it takes for radiation to travel the distance from an object and back.

Rice. 4 – Modern optical rangefinder

Fig. 5 – Optical rangefinder type “Seagull”

In rangefinders, it is not the line length itself that is measured, but some other quantity, relative to which the line length is a function.

As previously mentioned, 3 types of rangefinders are used in geodesy:

optical (geometric type rangefinders),

electro-optical (light range finders),

radio engineering (radio range finders).

4.1. Physical basis of measurements and principle of operation

Rice. 6 Geometric diagram of optical rangefinders

Suppose we need to find the distance AB. Let's place an optical rangefinder at point A, and a staff at point B perpendicular to line AB.

Let us denote: l - a section of the GM rail,
φ is 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 using the series expansion of the function Ctgφ, we can reduce formula (4.1.1) 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 which value - φ or l - is assumed to be constant, a distinction is made between 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 diastymometric 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 Filament rangefinder with constant angle

In the telescope reticle, as a rule, there are two additional horizontal threads located on both sides of the center of the reticle at equal distances from it; these are rangefinder threads (Fig. 7).

Let us draw the path of rays passing through the rangefinder threads in a Kepler tube with external focusing. The device is installed above point A; at point B there is a rail installed perpendicular to the sighting line of the pipe. You need to find the distance between points A and B.

Rice. 7 - Rangefinder threads

Let's construct the ray path from points m and g of the rangefinder threads. Rays from points m and g, running parallel to the optical axis, after refraction at the objective lens, will intersect this axis at the front focus point F and hit points M and G of the staff. The distance from point A to point B will be equal to:

D = l/2 * Ctg(φ/2) + fob + 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 ob - focal length of the lens;
l is the length of the segment MG on the rail.

Let us denote (f about + d) by c, and the value 1/2*Ctg φ/2 by 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 = ОF/m"O; m"O= p/2 (4.1.2.3)

Ctg φ/2 = (fob*2)/p, (4.1.2.4)

where p is the distance between the rangefinder threads. Next we write:

C = f rev / 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 threads. 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 slant distance with a thread rangefinder

Let the sighting line of the pipe JK, when measuring the distance AB, have an inclination angle ν, and the segment l is measured along the staff (Fig. 8). If the staff were installed perpendicular to the sight line of the pipe, then the inclined distance would be equal to:

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)

We determine the horizontal location of the line S from Δ JKE:

S = D*Cosν (4.1.3.4)

S= C*l*Cos2ν + c*Cosν. (4.1.3.5)

rice. 8 - Measuring slant distance with a thread rangefinder

For convenience of calculations, we take the second term equal to c*Cos2ν ; Since the value of c 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"* Cos2ν (4.1.3.7)

Usually the value (C*l + c) is called the rangefinder distance. Let us denote the difference (D" - S) by ΔD and call it the correction for reduction to the horizon, then

S = D" – ΔD (4.1.3.8)

ΔD = D" * Sin 2 ν (4.1.3.9)

The angle ν is measured with a vertical circle of theodolite; Moreover, the correction ΔD is not taken into account. The accuracy of measuring distances with a thread rangefinder is usually estimated by a relative error of 1/100 to 1/300.

In addition to the usual filament rangefinder, there are dual image optical rangefinders.

4.2 Design features and operating principle

In a pulsed light rangefinder, the radiation source 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 radiation pulse repetition rates of up to 50-100 Hz, semiconductor lasers - 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 combinations thereof. Injection lasers are controlled by injection current.

In phase 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 modes, light-finding radiation is modulated by interference, acousto-optical and electro-optical modulators. Microwave phase optical rangefinders use electro-optical modulators on cavity and waveguide microwave structures.

In pulse light range finders, photodiodes are usually used as a photoreceiving device; in phase light range finders, photo reception is carried out using photomultipliers. The sensitivity of the photoreceiving path of an optical rangefinder can be increased by several orders of magnitude by using optical heterodyning. The range of such an optical rangefinder is limited by the coherence length of the transmitting laser, and it is possible to register movements and vibrations of objects up to 0.2 km.

Measuring time intervals is most often carried out using the pulse-counting method.

5. Conclusion

A rangefinder is the best device for measuring distance over long distances. Nowadays laser rangefinders are also used in ground-based military equipment both in aviation and navy. A number of rangefinders have been adopted by many armies around the world. The rangefinder has also become an indispensable part of hunting, which makes it unique and very useful.

6. Bibliography

1. Gerasimov F.Ya., Govorukhin A.M. Brief topographic-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. Online optical store. Operating principles 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.htmlrangefinder 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) – mesh of threads; b) – scheme for determining... levels. Device technical levels. Depending on the devices, applied...

19

to Favorites to Favorites from Favorites 8

Dear colleagues, since the main hero “is an artillery officer, your humble servant had to understand a little about the issues of fire control in the period shortly before and the beginning of WWI. As I suspected, the question turned out to be very complicated, but we still managed to collect some information. This material in no way claims to be complete and comprehensive; it is only an attempt to bring together all the facts and guesses that I currently have.

Let’s try to understand the peculiarities of artillery shooting “on our fingers”. In order to aim a gun at a target, you need to set it to the correct sight (vertical pointing angle) and rear sight (horizontal pointing angle). In essence, all the sophisticated artillery science comes down to installing the correct sight and rear sight. However, it is easy to say, but difficult to do.

The simplest case is when our gun is stationary and standing on level ground and we need to hit the same stationary target. In this case, it would seem that it is enough to point the gun so that the barrel points directly at the target (and we will have the correct rear sight), and find out the exact distance to the target. Then, using artillery tables, we can calculate the elevation angle (sight), give it to the gun and boom! We'll hit the target.

In reality, this is, of course, not the case - if the target is far enough away, you need to make adjustments for the wind, air humidity, the degree of wear of the gun, the temperature of the gunpowder, etc. etc. – and even after all this, if the target is not too large, you will have to hit it properly from the cannon, since minor deviations in the shape and weight of the projectiles, as well as the weight and quality of the charges, will still lead to a certain spread of hits (ellipse dispersion). But if we fire a certain number of shells, then in the end, according to the law of statistics, we will definitely hit the target.

But we will put the problem of amendments aside for now, and consider the weapon and the target as such spherical horses in a vacuum. Let’s say shooting is done on an absolutely flat surface, with always the same humidity, no breeze, the gun is made of a material that is essentially non-fading, etc. and so on. In this case, when firing from a stationary cannon at a stationary target, it will indeed be enough to know the distance to the target, which gives us the vertical aiming angle (sight) and the direction towards it (rear sight)

But what if the target or weapon is not stationary? For example, what is it like in the navy? The gun is located on a ship that is moving somewhere at some speed. His target, the bastard, doesn’t stand still either; it can come at absolutely any angle to our course. And at absolutely any speed that her captain can think of. What then?

Since the enemy is moving in space and taking into account the fact that we are not shooting from a turbolaser, instantly hitting the target, and from a gun whose projectile needs some time to reach the target, it is necessary to make a lead, i.e. shoot not where the enemy ship is at the time of the shot, but where it will be 20–30 seconds later, by the time our projectile arrives.

It seems to be easy too - let’s look at it in the diagram.

Our ship is at point O, the enemy's is at point A. If, being at point O, our ship fires at the enemy from a cannon, then while the projectile is flying, the enemy ship will move to point B. Accordingly, during the flight of the projectile the following will change:

1. Distance to the target ship (was OA, will become OB);
2. Bearing to the target (it was angle S, but will become angle D)

Accordingly, in order to determine the sight correction, it is enough to know the difference between the lengths of the segments OA and OB, i.e. the magnitude of the change in distance (hereinafter referred to as VIR). And in order to determine the correction of the rear sight, it is enough to know the difference between the angles S and D, i.e. the magnitude of the bearing change (hereinafter referred to as VIP)

1. Distance to target ship (DA);
2. Target bearing (angle S);
3. Target course;
4. Target speed.

Now let’s look at how the information needed to calculate VIR and VIP was obtained.

1. Distance to the target ship - obviously, according to the rangefinder data. And even better - several rangefinders, preferably at least three. Then the most deviating value can be discarded, and the arithmetic mean taken from the other two. Determining distance using several rangefinders is obviously more effective

2. Target bearing (heading angle, if you will) - determined with half-finger-to-ceiling accuracy by any inclinometer, but for more accurate measurements it is advisable to have a sighting device - a device with high-quality optics, capable (among other things) of very accurately determining the heading angle goals. For sights intended for central aiming, the position of the target ship was determined with an error of 1-2 divisions of the rear sight of an artillery gun (i.e. 1-2 thousandths of the distance, at a distance of 90 kbt the position of the ship was determined with an accuracy of 30 meters)

3. Target course. This required arithmetic calculations and special artillery binoculars with divisions marked on them. It was done like this: first it was necessary to identify the target ship. Remember its length. Measure the distance to it. Convert the length of the ship into the number of divisions on artillery binoculars for a given distance. Those. calculate: “Sooo, the length of this ship is 150 meters, at 70 kbt a ship 150 meters long should occupy 7 divisions of artillery binoculars.” After this, look at the ship through artillery binoculars and determine how many divisions it actually occupies there. If, for example, the ship occupies 7 spaces, this means that it is facing us with its entire side. And if it’s less (let’s say 5 divisions), this means that the ship is located at some angle to us. Calculating, again, is not too difficult - if we know the length of the ship (i.e. the hypotenuse AB, in the example is equal to 7) and using artillery binoculars we determined the length of its projection (i.e. the leg AC in the example is length 5) then Calculating the angle S is an everyday matter.

The only thing I would like to add is that the same sighting device could play the role of artillery binoculars

4. Target speed. Now this was more difficult. In principle, the speed could be estimated “by eye” (with appropriate accuracy), but it is possible, of course, more accurately - knowing the distance to the target and its course, you can observe the target and determine its angular displacement speed - i.e. how quickly the bearing of the target changes. Next, the distance traveled by the ship is determined (again, you won’t have to calculate anything more complicated than right triangles) and its speed.

Here, however, one can ask - why, for example, do we complicate everything so much if we can simply measure changes in the VIP by observing the target ship through the sighting device? But here’s the thing: the change in VIP is nonlinear, and therefore current measurement data quickly becomes outdated.

The next question is what do we want from a fire control system (FCS)? Here's what.

The LMS should receive the following data:

1. Distance to the enemy target ship and bearing to it;
2. Course and speed of your own ship.

In this case, of course, the data must be constantly updated as quickly as possible.

1. Course and speed of the enemy target ship;
2. Convert course/speeds into a model of ship movement (friendly and enemy), with which you can predict the position of ships;
3. Lead for firing taking into account VIR, VIP and projectile flight time;
4. Sight and rear sight taking into account lead (taking into account all kinds of corrections (powder temperature, wind, humidity, etc.)).

The control system must transfer the sight and rear sight from the transmitting device in the conning tower (central post) to the artillery guns so that the functions of the gunners on the guns are minimal (ideally, the guns’ own sights are not used at all).

The control system must ensure salvo firing of guns selected by the senior artilleryman at his own chosen point in time.

Artillery fire control devices model 1910 manufactured by N.K. Geisler and K

They were installed on Russian dreadnoughts (both Baltic and Black Sea) and included many mechanisms for various purposes. All devices can be divided into giving (into which data was entered) and receiving (which produced some data). In addition to them, there were many auxiliary devices that ensured the operation of the others, but we will not talk about them; we will list the main ones:

Devices for transmitting rangefinder readings

The givers were located in the rangefinder room. They had a scale that allowed you to set the distance from 30 to 50 kbt with an accuracy of half a cable, from 50 to 75 kbt - 1 cablet, and from 75 to 150 kbt - 5 cablets. The operator, having determined the range using a rangefinder, set the corresponding value manually

The receivers were located in the conning tower and the CPU, and had exactly the same dial as the givers. As soon as the operator of the giving device set a certain value, it was immediately reflected on the dial of the receiving device.

Devices for transmitting the direction of targets and signals

Quite funny instruments, the task of which was to indicate the ship at which to fire (but by no means a bearing on this ship), and orders were given for the type of attack “shot/attack/shooting/volley/rapid fire”

The sending devices were located in the conning tower, the receiving devices were at each casemate gun and one for each tower. They worked similarly to devices for transmitting rangefinder readings.

Rear sight devices (devices for transmitting a horizontal sight)

This is where the confusion begins. With the giving instruments, everything is more or less clear - they were located in the conning tower and had a scale of 140 divisions, corresponding to the divisions of the gun sights (i.e. 1 division - 1/1000 of the distance). The receiving instruments were placed directly on the sighting devices of the guns. The system worked like this: the operator of the giving device in the conning tower (CP) set a certain value on the scale. Accordingly, the same value was shown on the receiving instruments, after which the gunner’s task was to turn the sighting mechanisms until the horizontal aiming of the gun coincided with the arrow on the instrument. Then - it seems like openwork, the gun is aimed correctly

There is a suspicion that the device did not provide a horizontal sight angle, but only a correction for lead. Not verified.

Devices for transmitting sight height

The most complex unit.

The giving devices were located in the conning tower (CP). Data about the distance to the target and VIR (the amount of change in distance, in case anyone forgot) was manually entered into the device, after which the device began to click something and display the distance to the target in the current time. Those. the device independently added/subtracted VIR from the distance and transmitted this information to the receiving devices.

The receiving devices, as well as the receiving rear sight devices, were installed on the sighting devices of the guns. But it was not the distance that appeared on them, but the sight. Those. devices for transmitting the height of the sight independently converted the distance into the angle of the sight and issued it to the guns. The process was running continuously, i.e. at each moment of time, the arrow of the receiving device showed the current sight on this moment. Moreover, corrections could be made to the receiving device of this system (by connecting several eccentrics). Those. if, for example, the gun was heavily shot and its firing range dropped, say, by 3 kbt compared to the new one, it was enough to install the corresponding eccentric - now an angle was added to the angle of the sight transmitted from the giving device, specifically for this gun, designed to compensate for the three-cable undershot. These were individual adjustments for each gun.

Using exactly the same principle, it was possible to introduce adjustments for the temperature of the gunpowder (it was taken to be the same as the temperature in the cellars), as well as adjustments for the type of charge/projectile “training/combat/practical”

But that's not all.

The fact is that the accuracy of the sight installation was “plus or minus a tram stop, adjusted for the azimuth of the North Star.” It was easy to make a mistake with both the range to the target and the size of the VIR. Special cynicism Another problem was that rangefinders always reported ranges with a certain delay. The fact is that the rangefinder determined the distance to the object at the moment the measurement began. But in order to determine this range, he had to perform a number of actions, including “picture alignment”, etc. All this required some time. It took some more time to report a certain range and set its value on the receiving device to transmit rangefinder readings. Thus, according to various sources, the senior artillery officer saw on the receiving device transmitting rangefinder readings not the current range, but the one that was almost a minute ago.

So, the device for transmitting the height of the sight gave the senior artilleryman the widest opportunities for this. At any time during the operation of the device, it was possible to manually enter a correction for the range or for the size of the VIR, and from the moment the correction was entered, the device continued the calculation taking it into account. It was possible to turn off the device altogether and set the sight values ​​manually. It was also possible to set the values ​​“jump” – i.e. if, for example, our device shows a sight of 15 degrees, then we can fire three volleys in a row - at 14, 15 and 16 degrees without waiting for the shells to fall and without introducing range/VIR adjustments, but the initial setting of the machine gun is not got lost.

And finally

Howlers and calls

The giving devices are located in the conning tower (CP), and the howlers themselves are located one at each gun. When the fire manager wants to fire a volley, he closes the corresponding circuits and the gunners at the guns fire shots.

Unfortunately, it is absolutely impossible to talk about the Geisler model 1910 as a full-fledged fire control system. Why?

1. Geisler's control system did not have a device that could determine the bearing of the target (there was no sighting device);
2. There was no instrument that could calculate its course and the speed of the target ship. So, having received the range (from the device for transmitting rangefinder readings) and having determined the bearing to it using improvised means, everything else had to be calculated manually;
3. There were also no instruments that would allow one to determine the course and speed of one’s own ship - they also had to be obtained “by means at hand,” that is, not included in Geisler’s kit;
4. There was no device for automatic calculation of VIR and VIP - i.e. Having received and calculated the courses/speeds of one’s own ship and target, it was necessary to calculate both VIR and VIP, again manually.

Thus, despite the presence of very advanced instruments that automatically calculate the height of the sight, Geisler’s control system still required very large quantity manual calculations - and that was not good.

Geisler's control system did not, and could not, exclude the use of gun sights by gunners. The fact is that the sight height automatic machine calculated the sight... of course, for the moment when the ship is on an even keel. And the ship experiences both longitudinal and lateral motion. And it was this that Geisler’s OMS did not take into account at all and in no way. Therefore, there is an assumption, very similar to the truth, that the task of the gunner was to “tweak” the aiming in such a way as to compensate for the ship’s pitching. It is clear that it was necessary to “twist” constantly, although there are doubts that the 305-mm guns could be “stabilized” manually. Also, if I am right that the Geisler control system did not transmit the horizontal aiming angle, but only the lead, then the gunner of each gun independently aimed his gun in the horizontal plane and only took the lead as ordered from above.

Geisler's fire control system allowed for salvo firing. But the senior artilleryman could not fire a simultaneous volley - he could give the signal to open fire, it is not the same. Those. Let's imagine a picture - four turrets of the Sevastopol, in each the gunners “adjust” the sights, compensating for the pitching. Suddenly - a howler! Some people's sights are fine, they shoot, but others haven't adjusted it yet, they tighten it up, fire a shot... and the difference of 2-3 seconds significantly increases the dispersion of the shells. Thus, giving a signal does not mean receiving a one-time salvo.

But what Geisler’s control system did really well was the transfer of data from the sending devices in the conning tower to the receiving devices at the guns. There were no problems here, and the system turned out to be very reliable and fast.

In other words, the Geisler instruments of the 1910 model were not so much a control system as a way of transmitting data from the commander to the guns (although the presence of an automatic calculation of the sight height gives the right to classify the Geisler specifically as a control system).

A sighting device appeared in Erickson’s control system, and it was connected to an electromechanical device that outputs the horizontal aiming angle. Thus, apparently, turning the sight led to an automatic displacement of the arrows on the sighting devices of the guns.

In Erickson's control system there were 2 central gunners, one of them was engaged in horizontal aiming, the second - vertical, and it was they (and not the gunners) who took into account the pitching angle - this angle was constantly measured and added to the aiming angle on an even keel. So the gunners could only adjust their guns so that the sight and rear sight corresponded to the values ​​of the arrows on the sighting devices. The gunner no longer needed to look through the gun sight.

Generally speaking, trying to “keep up” with the motion by manually stabilizing the gun looks strange. It would be much easier to solve the problem using a different principle - a device that would close the circuit and fire a shot when the ship was on an even keel. In Russia there were pitching control devices based on the operation of a pendulum. But alas, they had a fair amount of error and could not be used for artillery fire. To tell the truth, the Germans only had such a device after Jutland, but Erickson still produced results that were no worse than “manual stabilization.”

Salvo firing was carried out according to a new principle - now, when the gunners in the tower were ready, they pressed a special pedal, and the senior artilleryman closed the chain, pressing his own pedal in the conning tower (CP) as the towers were ready. Those. the volleys became truly simultaneous.

I don’t know whether Erickson had automatic calculation devices for VIR and VIP. But what is known reliably is as of 1911–1912. Erickson's OMS was tragically unprepared. The transmission mechanisms from giving devices to receiving devices worked poorly. The process took much longer than in Geisler's OMS, but inconsistencies constantly occurred. The pitch control devices worked too slowly, so that the sight and rear sight of the central gunners “could not keep up” with the pitching - with corresponding consequences for shooting accuracy. What was to be done?

Russian imperial fleet I took a rather original path. The newest battleships were equipped with the Geisler system, model 1910. And since the only control system they had was instruments for calculating the height of the sight, then, apparently, it was decided not to wait until the Erickson control system was perfected, and not to try to buy a new control system (let's say, from the British) entirely, and to acquire/implement the missing instruments and simply supplement the Geisler system with them.

An interesting sequence is given by Mr. Serg in Tsushima: http://tsushima.su/forums/viewtopic.php?id=6342&p=1

On January 11, MTK decided to install the Erickson system at Sevakh.
May 12 Erickson is not ready, a contract has been signed with Geisler.
On September 12, a contract was signed with Erickson for the installation of additional devices.
September 13, Erickson’s refinement of the Pollen device and Geisler’s AVP.
January 14 installation of a set of Pollen devices on the PV.
June 14, testing of Pollen devices on PV was completed
December 15, conclusion of a contract for the development and installation of central heating units.
16 autumn the installation of the central heating unit was completed.
17g firing with central nervous system.

As a result, the control system of our “Sevastopol” became a hodgepodge. The VIR and VIP calculation machines were supplied by English ones purchased from Pollen. The visors are from Erickson. The automatic machine for calculating the height of the sight was at first Geisler's, then it was replaced by Erickson's. To determine courses, they installed a gyroscope (but it’s not a fact that in WWII, maybe later...) In general, around 1916, our Sevastopols received a completely first-class central guidance system for those times.

What about our sworn friends?

It seems that the British had the best situation in Jutland. The guys from the island came up with the so-called “Dreyer Table”, which maximally automated the processes of developing vertical and horizontal sights.

The British had to take a bearing and determine the distance to the target manually, but the course and speed of the enemy ship were automatically calculated by the Dumaresque device. Again, as far as I understand, the results of these calculations were automatically transferred to the “Dreyer table”, which received data on its own heading/speed from some analogue of a speedometer and gyrocompass, built a model of the ships’ movement itself, calculated VIR and VIP. In our country, even after the advent of the Pollen device, which calculated the VIR, the transfer of the VIR to the automatic sight height calculation occurred like this - the operator read Pollen’s readings, then entered them into the automatic sight height calculation. For the British, everything happened automatically.

I tried to summarize the data on the LMS into a single table, and this is what came out:

Alas for me - the table probably suffers from many errors; the data on the German OMS is extremely lapidary: http://navycollection.narod.ru/library/Haase/artillery.htm

And in English - on English language which I don't know: http://www.dreadnoughtproject.org/tfs/index.php/Dreyer_Fire_Control_Table

I don’t know how the British solved the issue with compensation for longitudinal/transverse pitching. But the Germans did not have any compensating devices (they appeared only after Jutland).

Generally speaking, it turns out that the control system of the Baltic dreadnoughts was still inferior to the British, and was approximately on the same level as the Germans. True, with one exception.

The German Derflinger had 7 (in words SEVEN) rangefinders. And they all measured the distance to the enemy, and the average value was entered into the automatic sight calculation machine. The domestic Sevastopols initially had only two rangefinders (there were also so-called Krylov rangefinders, but they were nothing more than improved Lujol-Myakishev micrometers and did not provide high-quality measurements at long distances).

On the one hand, it would seem that such rangefinders (of much better quality than those of the British) provided the Germans with quick shooting in Jutland, but is this so? The same "Derflinger" took aim only from the 6th salvo, and then generally by accident (in theory, the sixth salvo should have resulted in a flight, the commander of the "Derflinger" Hase tried to take the British into the fork, however, to his surprise, there was a cover ). "Goeben" in general also did not show brilliant results. But we must take into account that the Germans still shot much better than the British, probably the German rangefinders have some merit in this.

But I believe that the better accuracy of German ships is not at all the result of superiority over the British in material terms, but a completely different system of training gunners.

Here I will allow myself to make some excerpts from the book Hector Charles Bywater and Hubert Cecil Ferraby"Strange Intelligence. Memoirs of Naval Secret Service". Constable, London, 1931: http://militera.lib.ru/h/bywater_ferraby/index.html

Under the influence of Admiral Thomsen, the German Navy began experimenting with long-range shooting in 1895... ...The new navy can afford to be less conservative than navies with old traditions. And therefore, in Germany, all new products capable of strengthening the combat power of the fleet were guaranteed official approval in advance...

The Germans, having made sure that shooting at long distances was feasible in practice, immediately gave their onboard guns the maximum possible aiming angle...

...If the German gun turrets already in 1900 allowed the guns to raise their barrels by 30 degrees, then on British ships the elevation angle did not exceed 13.5 degrees, which gave the German ships significant advantages. If war had broken out at that time, the German fleet would have significantly, even decisively, surpassed us in accuracy and range of fire...

...The Germans did not have a centralized fire control system “Fire-director”, installed, as already noted, on the ships of the British fleet for some time after the Battle of Jutland, but the effectiveness of their fire was confirmed by the results of this battle.

Of course, these results were the fruit of twenty years of intensive work, persistent and thorough, which is generally characteristic of the Germans. For every hundred pounds that we allocated in those years for artillery research, Germany allocated a thousand. Let's give just one example. Secret Service agents learned in 1910 that the Germans allocated much more shells for training than we did - for large-caliber guns - 80 percent more rounds. Live-fire exercises against armored target ships were a constant practice for the Germans, while in the British Navy they were very rare or even not carried out at all...

...In 1910, important exercises took place in the Baltic using the Richtungsweiser device installed on board the ships Nassau and Westphalen. A high percentage of hits on moving targets from distances up to 11,000 meters was demonstrated, and after certain improvements, new practical tests were organized.

But in March 1911, accurate and much-explaining information was received. It concerned the results of firing exercises conducted by a division of German warships equipped with 280 mm cannons at a towed target at an average distance of 11,500 meters in fairly rough seas and moderate visibility. 8 percent of the shells hit the target. This result was far superior to anything we had previously been told. Therefore, experts showed skepticism, but the evidence was quite reliable.

It was quite clear that the campaign was undertaken to test and compare the merits of target designation and guidance systems. One of them was already installed on the battleship Alsace, and the other, experimental, was installed on the Blucher. The shooting site was located 30 miles southwest of the Faroe Islands, the target was a light cruiser that was part of the division. It is clear that they did not shoot at the cruiser itself. It, as they say in the British Navy, was a “shifted target,” that is, aiming was carried out at the target ship, while the guns themselves were aimed with a shift at a certain angle and fired. The check is very simple - if the devices work correctly, the shells will fall exactly at the calculated distance from the stern of the target ship.

The fundamental advantage of this method, invented, according to their own statements, by the Germans, is that, without compromising the accuracy of the results obtained, it makes it possible to replace conventional targets in shooting, which, due to heavy engines and mechanisms, can only be towed at low speed and usually in good weather.

An assessment of “shift” shooting could only be called approximate to a certain extent, because it lacks the final fact - holes in the target, but on the other hand, the data obtained from it is sufficiently accurate for all practical purposes.

During the first experiment, Alsace and Blucher fired from a distance of 10,000 meters at a target, which was a light cruiser traveling at a speed of 14 to 20 knots.

These conditions were unusually harsh for the era, and it is not surprising that the report of the results of these shootings caused controversy, and even its accuracy was refuted by some British experts on naval artillery. However, this information was true, and the test results were indeed incredibly successful.

From 10,000 meters, "Alsace", armed with old 280-mm cannons, fired a three-gun salvo at the target's wake, that is, if the guns had not been aimed "with a shift", the shells would have hit the target exactly. The battleship easily accomplished the same thing when firing from a distance of 12,000 meters.

"Blücher" was armed with 12 new 210 mm guns. He also easily managed to hit the target, most of shells hit in the immediate vicinity or directly into the wake left by the target cruiser.

On the second day the distance was increased to 13,000 meters. The weather was good and a slight sea was rocking the ships. Despite the increased distance, "Alsace" shot well, as for "Blücher", it exceeded all expectations.

Moving at a speed of 21 knots, the armored cruiser caught the target ship, sailing at 18 knots, with the third salvo. Moreover, according to the estimates of experts who were on the target cruiser, it would be possible to confidently state that one or more shells hit each of the eleven subsequent salvoes. Given the relatively small caliber of guns, higher speed, with which both the “shooter” and the target, and the state of the sea were going, the result of the shooting at that time could be called phenomenal. All these details, and much more, were contained in the report sent by our agent to the Secret Service.

When the report reached the Admiralty, some old officers considered it erroneous or false. The agent who wrote the report was summoned to London to discuss the matter. He was told that the information about the test results he indicated in the report was “absolutely impossible”, that not a single ship would be able to hit a moving target at a distance of over 11,000 meters on the move, in general, that all this was fiction or a mistake.

Quite by chance, these results of German firing became known a few weeks before the first test by the British Navy of Admiral Scott's fire control system, nicknamed "Fire-director". His Majesty's ship Neptune was the first ship on which this system was installed. He conducted training exercises in March 1911 with excellent results. But official conservatism slowed down the introduction of the device on other ships. This situation lasted until November 1912, when comparative tests of the Director system installed on the Thunderer ship and the old system installed on Orion were carried out.

Sir Percy Scott described the teachings in the following words:

“The distance was 8200 meters, the “shooter” ships sailed at a speed of 12 knots, the targets were towed at the same speed. Both ships simultaneously opened fire immediately after the signal. The Thunderer shot very well. "Orion" sent its shells in all directions. Three minutes later the “Cease fire!” signal was given and the target was checked. As a result, it turned out that the Thunderer made six more hits than the Orion.

As far as we know, the first live firing in the British Navy at a distance of 13,000 meters took place in 1913, when the ship Neptune fired at a target from such a distance.

Those who followed the development of gunnery tools and techniques in Germany knew what we had to expect. And if anything came as a surprise, it was the fact that in the Battle of Jutland the ratio of the number of shells hitting the target to total number fired shells did not exceed 3.5.%

I will take the liberty of asserting that the quality of German shooting lay in the artillery training system, which was much better than that of the British. As a result, the Germans compensated for some of the superiority of the British in the fire control system with professionalism.

An optical rangefinder is an optical device used to measure distances to objects. Based on the principle of operation, rangefinders are divided into two main groups, geometric and physical types. The first group consists of geometric rangefinders. Measuring distances with a rangefinder of this type is based on determining the height h of an isosceles triangle ABC (diagram 10), for example, using the known side AB = I (base) and the opposite acute angle. One of the quantities, I or., is usually constant, and the other is variable ( measurable). Based on this feature, a distinction is made between rangefinders with a constant angle and rangefinders with a constant base. A constant-angle rangefinder is a telescope with two parallel threads in the field of view, and the base is a portable staff with equidistant divisions. The distance to the base measured by the rangefinder is proportional to the number of staff divisions visible through the telescope between the threads. Many geodetic instruments (theodolites, levels, etc.) work on this principle. The relative error of the filament rangefinder is 0.3-1%. More complex optical rangefinders with a constant base are built on the principle of combining images of an object constructed by beams that have passed through various optical rangefinder systems. The alignment is carried out 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 for 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. There are pulse and phase methods of range measurement. With the pulse method, a probing pulse is sent to the object, which triggers a time counter in the rangefinder. When the pulse reflected by the object returns to the rangefinder, it stops the counter. Based on the time interval (delay of the reflected pulse), using the built-in microprocessor, the distance to the object is determined: L= ct/2, where: L - distance to the object, s - speed of radiation propagation, t - time of passage of the pulse to the target and back. 10. Operating principle of a geometric type range finder 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 released. 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. The most common civilian electro-optical devices for measuring ranges are portable laser rangefinders, with which you can measure the distance to any object on the ground that is in the direct line of sight, with an error of about one meter. Maximum range determining the distance is individual for each model, usually from several hundred to one and a half thousand meters and highly depends on the type of object. It is best to measure ranges to large objects with high reflectivity, worst of all - to small objects that intensively absorb laser radiation. The laser rangefinder can be made in the form of a monocular or binoculars with magnification from 2 to 7 times. Some manufacturers integrate rangefinders into other optical devices, such as riflescopes. In the field of view of the rangefinder there is a special mark, which is aligned with the object, after which the range is measured, usually by simply pressing a button. The measurement result is displayed on the indicator panel located on the body of the device or reflected in the eyepiece, which allows you to obtain information about the range without taking your eyes off the rangefinder. Many models can display measurement results in different metric units (meters, feet, yards).