The operating principle of the rangefinder. Laser rangefinders, operating principle and purpose. Practical rangefinder measurements

Ranging.

The ability of electromagnetic radiation to propagate 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:
L = ct/2, 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.

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.

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.

With the phase ranging method, laser 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). Typically a sinusoidal signal with a frequency of 10...150 MHz (measuring frequency) is used. The reflected radiation enters the receiving optics and 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 determined.

Use of laser rangefinders for military purposes.

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, tanks), and in aviation (rangefinder, altimeter, target designator), and in the navy. This equipment has been combat tested in Vietnam and the Middle East. Currently, a number of rangefinders are adopted in the armies of a number of countries.

First laser rangefinder The XM-23 was tested in Vietnam and adopted by the US Army. It was designed for use in forward observation posts of ground forces. The radiation source in it was a laser with an output power of 2.5 W and a pulse duration of 30 ns. Integrated circuits were widely used in the design of the rangefinder. The emitter, receiver and optical elements are mounted in a monoblock, which has scales for precise reading of the azimuth and elevation angle of the target. The rangefinder was powered by a 24 V nickel-cadmium battery, providing 100 range measurements without recharging.

One of the first production models is a Swedish rangefinder designed for use in control systems of onboard ship and coastal artillery. The design of the rangefinder was particularly robust, which made it possible to use it in difficult conditions. The rangefinder could be interfaced, if necessary, with an image intensifier or television sight. The operating mode of the rangefinder provided for either measurements every 2 s for 20 s, or every 4 s for a long time.

Since the early 70s, laser rangefinders have been installed on foreign tanks. The installation of laser rangefinders on tanks immediately attracted the interest of foreign weapons 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. Compared to optical ones, they have a number of advantages: high speed, automated process of entering the measured range into sighting devices, high measurement accuracy, small size, weight, etc. For this, the AN/VVS-1 rangefinder was developed in the USA for the M60A tank. It did not differ in design from the laser artillery rangefinder on the ruby, however, in addition to issuing range data on a digital display, it had a device that provided range input into the calculating device of the tank’s fire control system. In this case, the range could be measured both by the gunner and the tank commander. The rangefinder operating mode is 15 measurements per minute for one hour.

Laser rangefinders installed on modern tanks allow you to measure the range to a target ranging from 200 m to 8,000 m (on American and French tanks) and from 200 to 10,000 m (on British and West German tanks) with an accuracy of 10 m. Most active elements of laser rangefinders currently installed on Western-made tanks and infantry fighting vehicles are based on a garnet crystal with an admixture of neodymium (the active element is a crystal of yttrium-aluminum garnet Y3A15O3, into which neodymium ions Ш3+ are introduced as active centers). These lasers generate radiation at a wavelength of 1.06 microns. There are also laser rangefinders in which the active element is a pink ruby crystal. Here the base is an aluminum oxide crystal Al2O3, and the active elements are chromium ions Cr3*. Ruby lasers generate radiation at a wavelength of 0.69 microns.

Recently, carbon dioxide laser rangefinders have begun to be used on foreign combat vehicles. In a CO2 laser, in a gas-discharge tube there is a mixture consisting of carbon dioxide (CO2), molecular nitrogen (N), and various small additives in the form of helium, water vapor, etc. The active centers are CO2 molecules. The advantage of the carbon dioxide laser is that its radiation (wavelength 10.6 microns) is relatively safe for vision and provides better penetration through smoke and fog. In addition, a constant-wave laser operating at this wavelength can be used to illuminate a target when working with a thermal imaging sight.

The rapid development of microelectronics has ensured a reduction in the weight and size of laser rangefinders, which has made it possible to create portable rangefinders. The Norwegian laser rangefinder LP-4 turned out to be very successful. It had an optical-mechanical shutter as a Q-switch. The receiving part of the rangefinder is also the operator's sight. The diameter of the optical system is 70 mm. The receiver is a portable photodiode. The counter is equipped with a range gating circuit, which 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 eye from exposure to its laser when receiving a reflected pulse. The emitter and receiver are mounted in one housing. The target elevation angle is determined to ~25 degrees. The battery provided 150 range measurements without recharging, its weight was only 1 kg. The rangefinder was purchased by Canada, Sweden, Denmark, Italy, and Australia.

Portable laser rangefinders were developed 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 six-fold monocular optical sight, 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. False signals reflected from nearby objects 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 circuits, which made it possible to increase the weight of the rangefinder together with the power source to 2 kg.

The next stage in the military use of laser rangefinders is their integration with the infantryman’s individual small arms.

An example is the F2000 assault rifle (Belgium). Instead of a sight, the F2000 can be equipped with a special fire control module, which includes a laser rangefinder and a ballistic computer. Based on the data on the range to the target, the computer sets the aiming mark of the sight both for firing from the machine gun itself and from the under-barrel grenade launcher (if installed).

The American OICW (Objective Individual Combat Weapon) system is an attempt to dramatically increase the effectiveness of the infantryman's weapons. The development is currently at the prototyping stage. The start of production is planned for 2008, entry into service - for 2009. According to current plans, there will be 4 OICWs per infantry squad. The OICW is a modular design consisting of three main modules: the "KE" (Kinetic Energy) module, which is a slightly upgraded Heckler-Koch G36 rifle; The "HE" (High Explosive) module, which is a self-loading 20 mm magazine-fed grenade launcher, installed on top of the "KE" module and using a trigger shared with the "KE" module for firing; and finally, a fire control module, which includes day/night television sights, a laser rangefinder and a ballistic computer, which automatically sets the aiming mark in the lens in accordance with the range to the target, and is also used to program remote fuses for 20 mm grenades. Before firing, based on data from a laser rangefinder, the grenade fuse is programmed to detonate in the air at a given range, which ensures that hidden targets are hit by shrapnel from above or from the side. Determining the range for remote detonation is carried out by counting the revolutions made by the grenade in flight.

Federal state budget

Educational institution

Kovrov State Technological Institute

Academy named after V.A. Degtyareva

Abstract on the topic:

“The principle of operation of a laser range finder”

Completed:

student of group U-112

Terekhova A.S.

Checked:

Kuznetsova S.V.

Kovrov 2014

History of creation

Principle of operation

Conclusion

History of the laser

The word “laser” is made up of the initial letters in the English phrase Light Amplification by Stimulated Emission of Radiation, which translated into Russian means: amplification of light through stimulated emission. Thus, the term laser itself reflects the fundamental role of stimulated emission processes that they play in generators and amplifiers of coherent light. Therefore, the history of laser creation should begin in 1917, when Albert Einstein first introduced the concept of stimulated emission.

This was the first step towards the laser. The next step was taken by the Soviet physicist V.A. Fabrikant, who in 1939 pointed out the possibility of using stimulated emission to amplify electromagnetic radiation as it passes through matter. The idea expressed by V. A. Fabrikant involved the use of microsystems with inverse population of levels. Later, after the end of the Great Patriotic War, V. A. Fabrikant returned to this idea and, based on his research, filed in 1951 (together with M. M. Vudynsky and F. A. Butaeva) an application for the invention of a method for amplifying radiation using stimulated emissions. A certificate was issued for this application, in which, under the heading “Subject of the Invention,” it was written: “A method of amplifying electromagnetic radiation (ultraviolet, visible, infrared and radio wavelengths), characterized in that the amplified radiation is passed through a medium in which, with the help of auxiliary radiation or in another way create an excess concentration of atoms, other particles or their systems at the upper energy levels corresponding to excited states compared to the equilibrium one."

Initially, this method of amplifying radiation was implemented in the radio range, or more precisely in the ultrahigh frequency range (microwave range). In May 1952, at the All-Union Conference on Radio Spectroscopy, Soviet physicists N. G. Basov and A. M. Prokhorov made a report on the fundamental possibility of creating a radiation amplifier in the microwave range. They called it a “molecular generator” (it was supposed to use a beam of ammonia molecules). Almost simultaneously, the proposal to use stimulated emission to amplify and generate millimeter waves was put forward at Columbia University in the USA by the American physicist Charles Townes.

In 1954, a molecular oscillator, soon called a maser, became a reality. It was developed and created independently and simultaneously in two parts of the globe - at the P. N. Lebedev Physical Institute of the USSR Academy of Sciences (a group led by N. G. Basov and A. M. Prokhorov) and at Columbia University in the USA (a group under the leadership of C. Townes).

Subsequently, the term “laser” was derived from the term “maser” as a result of replacing the letter “M” (the initial letter of the word Microwave) with the letter “L” (the initial letter of the word Light). The operation of both a maser and a laser is based on the same principle - the principle formulated in 1951 by V. A. Fabrikant. The appearance of the maser meant that a new direction in science and technology was born. At first it was called quantum radiophysics, and later it became known as quantum electronics.

Ten years after the creation of the maser, in 1964, at the ceremony dedicated to the Nobel Prize, Academician A. M. Prokhorov said: “It would seem that after the creation of masers in the radio range, quantum generators in the optical range would soon be created. However, this did not happen . They were created only five to six years later. How does this explain? There were two difficulties. The first difficulty was that resonators for the optical wavelength range were not proposed at that time, and the second was that specific systems and methods for obtaining inverse population in the optical range."

The six years mentioned by A. M. Prokhorov were indeed filled with those studies that ultimately made it possible to move from a maser to a laser. In 1955, N. G. Basov and A. M. Prokhorov substantiated the use of the optical pumping method to create an inverted population of levels. In 1957, N. G. Basov put forward the idea of using semiconductors to create quantum generators; At the same time, he proposed using specially treated surfaces of the sample itself as a resonator. Also in 1957, V.A. Fabrikant and F.A. Butaeva observed the effect of optical quantum amplification in experiments with an electric discharge in a mixture of mercury vapor and small amounts of hydrogen and helium. In 1958, A. M. Prokhorov and, independently of him, the American physicist C. Townes theoretically substantiated the possibility of using the phenomenon of stimulated emission in the optical range; They (as well as the American R. Dicke) put forward the idea of using open resonators, not volumetric ones (as in the microwave range), in the optical range. Note that a structurally open resonator differs from a volume resonator in that the side conducting walls are removed (the end reflectors that fix the resonator axis in space are retained) and the linear dimensions of the resonator are chosen to be large compared to the wavelength of the radiation.

In 1959, the work of N. G. Basov, B. M. Vul and Yu. M. Popov was published with a theoretical substantiation of the idea of semiconductor quantum generators and an analysis of the conditions for their creation. Finally, in 1960, a substantive article by N. G. Basov, O. N. Krokhin, Yu. M. Popov appeared, in which the principles of creation and theory of quantum generators and amplifiers in the infrared and visible ranges were comprehensively reviewed. At the end of the article, the authors wrote: “The absence of fundamental restrictions allows us to hope that in the near future generators and amplifiers will be created in the infrared and optical wavelength ranges.”

Thus, intensive theoretical and experimental research in the USSR and the USA brought scientists close to the creation of a laser at the very end of the 50s. Success fell to the lot of the American physicist T. Maiman. In 1960, his message appeared in two scientific journals that he had succeeded in generating radiation in the optical range from ruby. This is how the world learned about the birth of the first “optical maser” - a ruby laser. The first sample of the laser looked quite modest: a small ruby cube (1x1x1 cm), two opposite faces of which had a silver coating (these faces played the role of a resonator mirror), were periodically irradiated with green light from a high-power flash lamp, which covered the ruby cube like a snake. The generated radiation, in the form of red light pulses, was emitted through a small hole in one of the silver-plated faces of the cube.

In the same 1960, American physicists A. Javan, W. Bennett, and E. Herriot succeeded in generating optical radiation in an electric discharge in a mixture of helium and neon. Thus was born the first gas laser, the appearance of which was actually prepared by the experimental studies of V. A. Fabrikant and F. A. Butaeva, carried out in 1957.

Since 1961, lasers of various types (solid-state and gas) have taken a strong place in optical laboratories. New active media are being mastered, laser manufacturing technology is being developed and improved. In 1962-1963 The first semiconductor lasers were created simultaneously in the USSR and the USA.

Thus begins a new, “laser” period of optics. Since its inception, laser technology has developed at an extremely rapid pace. New types of lasers are appearing and at the same time old ones are being improved. This was the reason for the deep penetration of lasers into many sectors of the national economy.

Laser operating principle

Fig. 1 Laser operation diagram

The schematic diagram of the laser is extremely simple (Fig. 1): an active element placed between two mutually parallel mirrors. The mirrors form a so-called optical resonator; One of the mirrors is made slightly transparent, and a laser beam emerges from the resonator through this mirror. In order for the generation of laser radiation to begin, it is necessary to “pump” the active element with energy from some source (it is called a pumping device).

Indeed, the main physical process that determines the action of a laser is stimulated emission of radiation. It occurs when a photon interacts with an excited atom and the photon energy coincides with the excitation energy of the atom (or molecule).

As a result of this interaction, the excited atom goes into an unexcited state, and the excess energy is emitted in the form of a new photon with exactly the same energy, direction of propagation and polarization as that of the primary photon. Thus, the consequence of this process is the presence of two absolutely identical photons. With the further interaction of these photons with excited atoms similar to the first atom, a “chain reaction” of multiplication of identical photons “flying” absolutely exactly in one direction may occur, which will lead to the appearance of a narrowly directed light beam. For an avalanche of identical photons to occur, a medium is required in which there would be more excited atoms than unexcited ones, since photon absorption would occur when photons interact with unexcited atoms. Such a medium is called a medium with an inverse population of energy levels (Fig. 2).

Fig.2. Schematic representation of a medium with an inverted population of energy levels.

So, in addition to the forced emission of photons by excited atoms, the process of spontaneous emission of photons also occurs during the transition of excited atoms to an unexcited state and the process of absorption of photons during the transition of atoms from an unexcited state to an excited one. These three processes, accompanying the transitions of atoms to excited states and back, were postulated, as mentioned above, by A. Einstein in 1916.

If the number of excited atoms is large, and there is an inverse population of levels (there are more atoms in the upper, excited state than in the lower, unexcited state), then the very first photon born as a result of spontaneous emission will cause an increasing avalanche of the appearance of photons identical to it. There will be an increase in spontaneous emission.

With the simultaneous birth (in principle possible) of a large number of spontaneously emitted photons, a large number of avalanches arise, each of which will propagate in its own direction, specified by the initial photon of the corresponding avalanche.

Fig.3. Spontaneously generated photons, the direction of propagation of which is not perpendicular to the plane of the mirrors, create avalanches of photons that extend beyond the boundaries of the medium

As a result, we will receive streams of light quanta, but we will not be able to obtain either a directed beam or high monochromaticity, since each avalanche was initiated by its own initial photon. In order for a medium with an inverted population to be used to generate a laser beam, i.e., a directed beam with high monochromaticity, it is necessary to “remove” the inverted population using primary photons that already have the same radiation direction and the same energy , coinciding with the energy of a given transition in the atom. In this case we will have a laser light amplifier.

There is, however, another option for obtaining a laser beam, which involves the use of a feedback system. In Fig. Figure 3 shows that spontaneously generated photons, the direction of propagation of which is perpendicular to the plane of the mirrors, create avalanches of photons that extend beyond the boundaries of the medium. At the same time, photons, the direction of propagation of which is perpendicular to the plane of the mirrors, will create avalanches that are greatly amplified in the medium due to multiple reflections from the mirrors. If one of the mirrors has a small transmission, then a directed stream of photons will exit through it perpendicular to the plane of the mirrors. With properly selected transmission of the mirrors, their precise adjustment relative to each other and relative to the longitudinal axis of the medium with an inverted population, the feedback can be so effective that the “sideways” radiation can be completely neglected in comparison with the radiation emerging through the mirrors. In practice, this can actually be done. This feedback circuit is called an optical cavity, and it is this type of cavity that is used in most existing lasers.

Some unique properties of laser radiation

Let's consider some unique properties of laser radiation. In spontaneous emission, an atom emits a spectral line of finite width. With an avalanche-like increase in the number of stimulated emitted photons in a medium with an inverted population, the radiation intensity of this avalanche will increase, first of all, in the center of the spectral line of a given atomic transition, and as a result of this process, the width of the spectral line of the initial spontaneous emission will decrease. In practice, under special conditions, it is possible to make the relative width of the spectral line of laser radiation 107 - 108 times smaller than the width of the narrowest spontaneous emission lines observed in nature.

In addition to narrowing the radiation line in the laser, it is possible to obtain a beam divergence of less than 10-4 radians, i.e., at the level of arcseconds.

It is known that a directed narrow beam of light can be obtained, in principle, from any source by placing a number of screens with small holes located on the same straight line in the path of the light flow. Let's imagine that we took a heated black body and, using diaphragms, obtained a beam of light, from which, using a prism or other spectral device, we isolated a beam with a spectral width corresponding to the width of the spectrum of laser radiation. Knowing the power of laser radiation, the width of its spectrum and the angular divergence of the beam, one can use Planck’s formula to calculate the temperature of an imaginary black body used as a source of a light beam equivalent to a laser beam. This calculation will lead us to a fantastic figure: the temperature of the black body should be on the order of tens of millions of degrees! An amazing property of a laser beam - its high effective temperature (even at a relatively low average laser radiation power or low laser pulse energy) opens up great opportunities for researchers that are absolutely not feasible without the use of a laser.

Application of lasers in various technological processes

laser radiation technological power

The advent of lasers immediately had and continues to have an impact on various fields of science and technology, where it became possible to use lasers to solve specific scientific and technical problems. The conducted research confirmed the possibility of significant improvement of many optical devices and systems when using lasers as a light source and led to the creation of fundamentally new devices (brightness amplifiers, quantum gyrometers, high-speed optical circuits, etc.). Before the eyes of one generation, new scientific and technical areas were formed - holography, nonlinear and integrated optics, laser technologies, laser chemistry, the use of lasers for controlled thermonuclear fusion and other energy problems. Below is a short list of applications of lasers in various fields of science and technology, where the unique properties of laser radiation have provided significant progress or led to completely new scientific and technical solutions.

High monochromaticity and coherence of laser radiation ensure the successful use of lasers in spectroscopy, initiation of chemical reactions, isotope separation, in systems for measuring linear and angular velocities, in all applications based on the use of interference, in communication and light-location systems. Of particular note, obviously, is the use of lasers in holography.

The high energy density and power of laser beams, the ability to focus laser radiation into a small spot are used in laser thermonuclear fusion systems, in such technological processes as laser cutting, welding, drilling, surface hardening and dimensional processing of various parts. These same properties and the direction of laser radiation ensure the successful use of lasers in military equipment.

The directionality of laser radiation and its low divergence are used in determining directions (in construction, geodesy, cartography), for targeting and target designation, in location, including for measuring distances to artificial Earth satellites, in communication systems through space and underwater communications.

With the creation of lasers, tremendous progress has occurred in the development of nonlinear optics, the study and use of phenomena such as harmonic generation, self-focusing of light beams, multiphoton absorption, and various types of light scattering caused by the laser radiation field.

Lasers are successfully used in medicine: in surgery (including eye surgery, destruction of kidney stones, etc.) and the treatment of various diseases, in biology, where focusing into a small spot makes it possible to act on individual cells or even parts of them.

Most of the above areas of laser application represent independent and extensive branches of science or technology and naturally require independent consideration. The purpose of the brief and incomplete list of laser applications given here is to illustrate the enormous impact that the advent of lasers has had on the development of science and technology, on the life of modern society.

Application of lasers in the jewelry industry

In recent years, there has been a tendency to expand the use of lasers in the jewelry industry. The most widely used are machines for processing with solid-state lasers on yttrium aluminum garnet, the radiation of which is quite well absorbed by the main materials of the jewelry industry - precious metals and stones. Some of the technological processes of laser processing have been fully developed and implemented in the jewelry industry, some processes and technologies are under development, and perhaps in the near future they can be used for processing jewelry industry products. Therefore, I will try to consider all possible options for using lasers in technological processes in the jewelry industry.

Punching holes in stones. One of the first uses of lasers was to punch holes in watch stones. Drilling holes has always been an extremely labor-intensive operation. Modern laser technology allows you to pierce holes of the required shape in stones of various types with high speed and quality.

Laser welding. One of the first applications of lasers in the jewelry industry was repairs of various products using laser welding. An example of the use of laser welding in serial mass production is laser welding of chains during their production.

Rice. 4. Types of welded chains.

Rice. 5. Example of laser welding of a gold hairpin

Indeed, everyone knows and successfully uses equipment for the production of chains, especially from Italian companies. A special feature of this process is its two-stage nature: first, a chain is formed, then it is soldered using traditional methods. Lasers make it possible to weld a chain link directly during its formation using one technological operation and the same equipment. This technology was first developed for welding gold chains by the Italian company Laservall. It is also possible to use welding when connecting various components of jewelry, fastening the needles of signs (Fig. 2), welding a large ring for a lock, etc. The advantages of laser welding are the locality of heat input, the absence of fluxes and filler material (solder), low material losses during welding, the ability to connect product parts with stones, practically without heating the entire product as a whole. It should be especially noted that laser welding is one of the most complex technological processes and requires development of technology (assembly rules, welding modes, preparation and design of a welding unit) in almost every case of application of this process.

Laser welding with additive (surfacing). Such a process can be carried out similarly to welding, but with the remelting of additional filler material - solder - in the welding zone. This way, the issue of welding internal voids and cavities of products that open during polishing and grinding of products after casting, as well as welding joints with large gaps can be resolved.

Laser marking and engraving. One of the most interesting methods of processing precious metals is marking and engraving. Modern lasers, equipped with computer control, make it possible to apply almost any graphic information - drawings, inscriptions, monograms, logos - onto metal using laser marking and engraving (surface modification under the influence of laser radiation). Moreover, the image can be applied both in raster and contour images. Modern equipment allows you to move the laser beam at a speed of more than two meters per minute and provide graphic resolution on metal up to 10...15 lines per millimeter. Using this technique, it is possible to produce various pendants, hairpins, and other jewelry with unique laser graphics at a low cost (Fig. 3). Another interesting application of laser engraving technology is the laser application of various logos, monograms of owners, trademarks and signs on elements of tableware, both from precious metals and non-precious metals, for example, to indicate “stainless.” on knife blades.

Fig.6. Samples of laser marking and engraving of jewelry.

High resolution (thin lines), accuracy and repeatability (less than 5 microns) of a graphic pattern on metal makes it possible to effectively use a laser for marking the markings of products for further manual engraving, for example, in the manufacture of memorial signs, medals or tools for their production. A wide range of laser processing modes allows precise dosing of laser radiation energy, which in turn provides the possibility of high-precision processing of two-layer materials, such as jewelry made of base metals pre-varnished. Removing varnish under the influence of laser radiation without disturbing the geometric parameters of the metal surface makes it possible to subsequently carry out galvanic deposition of precious metal of almost any graphic image and obtain an unusual product.

Diamond marking. The modern development of lasers and laser technology, the improvement of laser radiation parameters, and the development of fundamentally new laser emitters have opened up the possibility of marking diamonds.

Rice. 4. Appearance of synthetic diamond markings.

According to Jewelry Review magazine, the American Institute of Gemology, in order to improve the characteristics of the diamond market, has begun laser marking diamonds weighing 0.99 carats or more. Similar work is being carried out in Russia. So in Fig. 4. An example of applying a laser image to a synthetic diamond is given, which in terms of physical and chemical properties is very close to natural stone and is a good model material for studying the technological process of marking diamonds. Since the size of clearly identifiable marks in the above figure is about 125 microns, this opens up the possibility of laser marking on the girdle of diamonds weighing from 0.2 carats, since the size of the girdle is about 200 microns. This is a very promising technology.

Branding. Branding is a type of laser marking where an image is formed on metal as a result of projecting a pre-created design with a laser beam. This method makes it easy to obtain small dimensions on metal and is used to set the name of the manufacturer of the product and assay marks. High resolution allows you to obtain images with a high degree of protection against reproduction (counterfeiting) and can be used for setting hallmarks.

The mark on a product is at the same time a sign of its quality. The laser branding technology does not lead to loss of product quality, does not require stamping operations, and is highly productive and ergonomic. The use of laser marking on lightweight and thin-walled products made of precious metals is especially effective.

Ground laser rangefinders. 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.

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. Using the previously discussed formula, we will 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 10-9 s. Since we can assume that the speed of light is 3*1010 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. This is well illustrated in the section on geodetic rangefinders. Let us estimate the error of a phase rangefinder suitable for working in field conditions. Experts say that it is not difficult for an operator (not a very qualified soldier) 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.

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 has a 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 10-9 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, however, 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. Installation name Kobelda . 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. Laser rangefinder included in the system Kobelda , allows you to measure the range simultaneously to two targets located on target. The system is fast-acting, allowing you to fire a shot in the shortest possible time.

If for stationary targets the probability of defeat when using a laser system compared to the probability of defeat when using a system with a stereo rangefinder is not much different 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. Various types of photodetectors are used in tracking channels. 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*10-8 W. 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 angle. 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, resonator mirrors, and a Q-switch. 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 one another, 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 about 5*10-8 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.

Airborne laser systems. Foreign press reports that laser rangefinders and altimeters have become widely used in military aviation of the US and NATO countries; they provide high accuracy in measuring range or altitude, have small dimensions and are easily integrated into the fire control system. In addition to these tasks, laser systems are now tasked with a number of other tasks. These include guidance and targeting. Laser guidance and target designation systems are used in helicopters, airplanes and unmanned aerial vehicles. They are divided into semi-active and active. The principle of constructing a semi-active system is as follows: the target is irradiated with laser radiation either continuously or pulsed, but in such a way as to prevent the loss of the target of the laser homing system, for which the appropriate sending frequency is selected. The target is illuminated either from a ground or aerial observation post; The laser radiation reflected from the target is perceived by a homing head mounted on a missile or bomb, which determines the error in the mismatch between the position of the optical axis of the head and the flight path. This data is entered into the control system, which ensures precise guidance of the missile or bomb at the target illuminated by the laser.

Laser systems cover the following types of ammunition: bombs, air-to-ground missiles, naval torpedoes. The combat use of laser homing systems is determined by the type of system, the nature of the target and the conditions of combat operations. For example, for guided bombs, the target designator and the bomb with a homing head can be on the same carrier.

To combat tactical ground targets in foreign laser systems, target designation can be carried out from helicopters or using ground-based portable target designators, and engagement can be carried out from helicopters or airplanes. But the difficulty of using target designators from air carriers is also noted. This requires a sophisticated stabilization system to keep the laser spot on the target.

Laser reconnaissance systems. For aerial reconnaissance, foreign armies use a variety of means: photographic, television, infrared, radio, etc. It is reported that the greatest capacity of useful information is provided by photo reconnaissance means. But they have such disadvantages as the impossibility of conducting covert reconnaissance at night, as well as long processing times for transmissions and provision of materials carrying information. Television systems allow you to transmit information quickly, but they do not allow you to work at night and in difficult weather conditions. Radio systems allow you to work at night and in bad weather conditions, but they have a relatively low resolution.

The operating principle of the aerial reconnaissance laser system is as follows. Radiation from an on-board carrier irradiates the area being explored and objects located on it reflect the radiation falling on it in different ways. You can notice that the same object, depending on what background it is located on, has a different brightness coefficient, therefore, it has unmasking features. It is easy to distinguish it from the surrounding background. Reflected by the underlying surface and objects located on it, laser radiation is collected by the receiving optical system and directed to the sensitive element. The receiver converts the radiation reflected from the surface and the electrical signal, which will be modulated in amplitude depending on the brightness distribution. Since in laser reconnaissance systems, as a rule, line-frame scanning is implemented, such a system is close to a television one. A narrow laser beam unfolds perpendicular to the direction of flight of the aircraft. At the same time, the radiation pattern of the receiving system is also scanned. This ensures that the image line is formed. Scanning across the frame is ensured by the movement of the aircraft. The image is recorded either on photographic film or can be produced on the screen of a cathode ray tube.

Holographic indicators on the windshield. A holographic windshield indicator was developed for use in the night vision targeting and navigation system intended for the F-16 fighter and the A-10 attack aircraft. Due to the fact that the dimensions of the aircraft cabin are small, in order to obtain a large instantaneous field of view of the indicator, the developers decided to place a collimating element under the instrument panel. The optical system includes three separate elements, each of which has the properties of diffractive optical systems: the central curved element acts as a collimator, the other two elements serve to change the position of the beams. A method has been developed for displaying combined information on one screen: in the form of a raster and in a line form, which is achieved by using the reverse beam path when forming a raster with a time interval of 1.3 ms, during which information is reproduced on the TV screen in alphanumeric form and in the form graphic data generated by the line method. A narrow-band phosphor is used for the indicator TV tube screen, which ensures good selectivity of the holographic system when reproducing images and transmission of light without a pink tint from the external environment. In the process of this work, the problem of bringing the observed image into correspondence with the image on the indicator when flying at low altitudes at night was solved (the night vision system gave a slightly enlarged image), which the pilot could not use, since this would somewhat distort the picture that could be obtained by visual inspection. Studies have shown that in these cases the pilot loses confidence and tends to fly at a lower speed and at a higher altitude. It was necessary to create a system that would provide a valid image of a size large enough so that the pilot could fly the aircraft visually at night and in adverse weather conditions, only occasionally checking the instruments. This required a wide field of the indicator, which expands the pilot’s capabilities to pilot the aircraft, detect targets off the route and carry out an anti-aircraft route and maneuver to attack targets. To ensure these maneuvers, a large field of view in elevation and azimuth is required. As the aircraft's bank angle increases, the pilot must have a wide vertical field of view. Installation of the collimating element as high as possible and close to the pilot’s eyes was achieved through the use of holographic elements as mirrors to change the direction of the beam of rays. Although this complicated the design, it made it possible to use simple and cheap holographic elements with high returns.

In the United States, a holographic coordinator is being developed to recognize and track targets. The main purpose of such a correlator is to generate and monitor missile guidance control signals in the middle and final sections of the flight path. This is achieved by instantly comparing images of the earth's surface located in the system's field of view in the lower and front hemisphere with images of various sections of the earth's surface along a given trajectory stored in the system's memory device. This ensures the ability to continuously determine the location of the missile on its trajectory using nearby surface areas, which allows for course correction in conditions of partial obscuration of the area by clouds. High accuracy at the final stage of flight is achieved using correction signals with a frequency of less than 1 Hz. The missile control system does not require an inertial coordinate system and coordinates of the exact position of the target. Reportedly, the initial data for this system should be provided by preliminary aerial or space reconnaissance and consist of a series of sequential frames representing Fourier spectrum images or panoramic photographs of the terrain, as is done when using the existing areal terrain correlator. The use of this scheme, according to experts, will make it possible to launch missiles from a carrier located outside the enemy’s air defense zone, from any height and trajectory point, from any angle, and will ensure high noise immunity, guiding guided weapons after launch at pre-selected and well-camouflaged stationary targets. The sample equipment includes an input lens, a device for converting a current image operating in real time, a holographic lens matrix matched with a holographic laser storage device, an input photodetector and electronic components. A special feature of this scheme is the use of a lens matrix of 100 elements having a 10x10 format. Each elementary lens provides an overview of the entire input equipment and, therefore, the entire signal from the image of the terrain or target entering the input. At a given focal plane, correspondingly 100 Fourier spectra of this input signal are formed. Thus, the instantaneous input signal is addressed simultaneously to 100 memory positions. In accordance with the lens matrix, a high-capacity holographic memory is manufactured using matched filters and taking into account the necessary application conditions. It is reported that during the testing phase of the system, a number of its important characteristics were identified. High detection ability both at low and high image contrast, the ability to correctly identify the input

information, even if only part of it is available. Possibility of smooth automatic transition of tracking signals when replacing one image of the area with another contained in the storage device.

Application of lasers in computer technology

The main example of the operation of semiconductor lasers is the magnetic-optical storage device (MO).

The MO drive is built on a combination of magnetic and optical principles of information storage. Information is written using a laser beam and a magnetic field, and read using only a laser.

During the recording process on an MO disk, a laser beam heats certain points on the disk, and under the influence of temperature, the resistance to polarity change for a heated point drops sharply, which allows the magnetic field to change the polarity of the point. After heating is completed, the resistance increases again, but the polarity of the heated point remains in accordance with the magnetic field applied to it at the moment of heating. In current MO drives, two cycles are used to write information, an erase cycle and a write cycle. During the erase process, the magnetic field has the same polarity, corresponding to binary zeros. The laser beam sequentially heats the entire erased area and thus writes a sequence of zeros to the disk. During the write cycle, the polarity of the magnetic field is reversed, which corresponds to a binary one. In this cycle, the laser beam is turned on only in those areas that should contain binary ones, leaving areas with binary zeros unchanged.

In the process of reading from a MO disk, the Kerr effect is used, which consists in changing the plane of polarization of the reflected laser beam, depending on the direction of the magnetic field of the reflecting element. The reflective element in this case is a point on the disk surface magnetized during recording, corresponding to one bit of stored information. When reading, a laser beam of low intensity is used, which does not lead to heating of the read area, thus, when reading, the stored information is not destroyed.

This method, unlike the usual one used in optical discs, does not deform the surface of the disc and allows repeated recording without additional equipment. This method also has an advantage over traditional magnetic recording in terms of reliability. Since remagnetization of disk sections is possible only under the influence of high temperature, the probability of accidental magnetization reversal is very low, in contrast to traditional magnetic recording, the loss of which can be caused by random magnetic fields.

The scope of application of MO disks is determined by its high characteristics in terms of reliability, volume and replaceability. An MO disk is necessary for tasks that require large disk space, such as CAD and sound image processing. However, the low speed of data access does not make it possible to use MO disks for tasks with critical system reactivity. Therefore, the use of MO disks in such tasks comes down to storing temporary or backup information on them. A very beneficial use for MO disks is for backing up hard drives or databases. Unlike tape drives traditionally used for these purposes, storing backup information on MO disks significantly increases the speed of data recovery after a failure. This is explained by the fact that MO disks are random access devices, which allows you to recover only the data that has failed. In addition, with this recovery method there is no need to completely stop the system until the data is completely restored. These advantages, combined with high reliability of information storage, make the use of MO disks for backup profitable, although more expensive compared to tape drives.

The use of MO disks is also advisable when working with large volumes of private information. Easy replacement of disks allows you to use them only during work, without worrying about protecting your computer during non-working hours; data can be stored in a separate, protected place. This same property makes MO disks indispensable in situations where it is necessary to transport large volumes from place to place, for example, from work to home and back.

The main prospects for the development of MO disks are primarily related to increasing the speed of data recording. The slow speed is determined primarily by the two-pass recording algorithm. In this algorithm, zeros and ones are written in different passes, due to the fact that the magnetic field that sets the direction of polarization of specific points on the disk cannot change its direction quickly enough.

The most realistic alternative to two-pass recording is a technology based on phase change. Such a system has already been implemented by some manufacturing companies. There are several other developments in this direction related to polymer dyes and modulations of the magnetic field and laser radiation power.

Technology based on a change in phase state is based on the ability of a substance to transition from a crystalline state to an amorphous one. It is enough to illuminate a certain point on the surface of the disk with a laser beam of a certain power, and the substance at this point will turn into an amorphous state. In this case, the reflectivity of the disk at this point changes. Writing information occurs much faster, but during this process the surface of the disk is deformed, which limits the number of rewriting cycles.

The technology, based on polymer dyes, also allows for repeated recording. With this technology, the surface of the disk is covered with two layers of polymers, each of which is sensitive to light of a certain frequency. For recording, a frequency is used that is ignored by the upper layer, but causes a reaction in the lower one. At the point of incidence of the beam, the lower layer swells and forms a bulge, which affects the reflective properties of the disk surface. For erasing, a different frequency is used, to which only the top layer of the polymer reacts; during the reaction, the bulge is smoothed out. This method, like the previous one, has a limited number of recording cycles, since the surface is deformed during recording.

Currently, technology is being developed that allows the polarity of a magnetic field to be reversed in just a few nanoseconds. This will allow the magnetic field to change synchronously with the arrival of data for recording. There is also a technology based on modulation of laser radiation. In this technology, the drive operates in three modes - low-intensity read mode, medium-intensity write mode and high-intensity write mode. Modulating the intensity of the laser beam requires a more complex disk structure, and the addition of an initializing magnet mounted in front of the bias magnet and having the opposite polarity to the disk drive mechanism. In the simplest case, the disk has two working layers - initializing and recording. The initializing layer is made of such a material that the initializing magnet can change its polarity without additional laser exposure. During the recording process, the initializing layer is written with zeros, and when exposed to a medium-intensity laser beam, the recording layer is magnetized by the initializing one; when exposed to a high-intensity beam, the recording layer is magnetized in accordance with the polarity of the bias magnet. Thus, data recording can occur in one pass, when switching laser power.

Of course, MO disks are promising and rapidly developing devices that can solve emerging problems with large volumes of information. But their further development depends not only on the technology of recording on them, but also on progress in the field of other storage media. And unless a more efficient way to store information is invented, MO disks may become dominant.

Conclusion

Recently, extensive research has been carried out in Russia and abroad in the field of quantum electronics, and various lasers have been created, as well as devices based on their use. Lasers are now used in location and communications, in space and on earth, in medicine and construction, in computer technology and industry, and in military technology. A new scientific direction has emerged - holography, the formation and development of which is also unthinkable without lasers.

However, the limited scope of this work did not allow us to note such an important aspect of quantum electronics as laser thermonuclear fusion, the use of laser radiation to produce thermonuclear plasma, and the stability of light compression. Such important aspects as laser separation of isotopes, laser production of pure substances, laser chemistry and much more are not considered.

We don’t know yet, what if a scientific revolution in the world, based on today's achievements of laser technology. It is quite possible that in 50 years reality will be much richer than our imagination...

Maybe by moving to time machine 50 years into the future, we will see a world hidden under the gun of lasers. Powerful lasers aimed from cover at spacecraft and satellites. Special mirrors in near-Earth orbits prepared to reflect a merciless laser beam in the right direction and direct it to the desired target. Powerful gamma lasers hover at a great height, the radiation of which is capable of destroying all life in any city on Earth in a matter of seconds. And there is nowhere to hide from the menacing laser beam - except to hide in deep underground shelters.

But this is all fantasy. And God forbid it turns into reality.

All this depends on us, on our actions today, on how actively we all treat the achievements of our mind correctly, and direct our decisions in a worthy direction of this vast rivers , whose name is laser.

List of used literature

Aviation and Cosmonautics No. 5 1981 from 44-45
Gorny S.G. “Use of lasers in the jewelry industry” 2002.
Donina N.M. The emergence of quantum electronics. M.: Nauka, 1974.
Quantum Electronics M.: Soviet Encyclopedia, 1969.
Karlov N.V. Lectures on quantum electronics. M.: Nauka, 1988.
Lasers in aviation (edited by Sidorin V.M.) Military Publishing House 1982
Petrovsky V.I. Laser locators Voenizdat
Ready J. Industrial application of lasers World 1991
Priezzhev A.V., Tuchin V.V., Shubochkin L.P. Laser diagnostics in biology and medicine. M.: Nauka, 1989.
Tarasov L.V. Meet lasers Radio and communications 1993
Tarasov L.V. Lasers reality and hopes, published by Science 1985
Tarasov L.V. Physics of processes in coherent optical generators
Fedorov B.F. Laser devices and aircraft systems Mechanical engineering 1988

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Test and coursework in the discipline

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control and navigation systems"

on the topic “Laser rangefinders”

Completed by: student gr. 130801

Volynkin P.N.

Checked by: Likhosherst V.V.

Introduction……………………………………………………………………...3 pages

1. Advantages of a laser rangefinder………………..…………………..4 page

2. Design and principle of operation………………………………………….. 5 pages

4. Example of a laser range finder…………………………………………....6 page

5. History of development.................................................. ...........................................7 page

Conclusion................................................. ........................................................ ....9 pages

Introduction

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

Widely used in engineering geodesy, topographical surveys, military affairs, navigation, astronomical research, and photography. Modern laser rangefinders are in most cases compact and allow you to determine distances to objects of interest in the shortest possible time and with great accuracy.

Laser rangefinders differ in operating principle: pulse and phase.

A pulsed laser rangefinder is a device consisting of a pulsed laser and a 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.

A phase laser rangefinder is a rangefinder whose operating principle is based on the method of comparing the phases of the sent and reflected signals. Phase rangefinders have higher measurement accuracy compared to pulse rangefinders. Phase rangefinders are also cheaper to manufacture. It is phase rangefinders that have become widespread in everyday life.

Advantages of a laser rangefinder

Firstly, you can measure distances alone; you just need to point the device at the target and press a button. This lightweight and compact instrument is convenient and easy to use, and allows you to accurately measure not only the length, but also the width and height of objects, calculate volumes and areas, and also perform arithmetic calculations. At the same time, the laser rangefinder allows you to save measurement results in its memory.

In addition, unlike traditional steel or fabric tape measures, laser rangefinders are practically not subject to wear over time - you just need to change the batteries on time. And, of course, the undeniable advantages of laser rangefinders are high measurement accuracy, speed of operation, ease of operation and reliable protection from dust and moisture. If you drop the rangefinder in the mud, quickly and carefully rinse it under running water and continue working. Some models of laser tape measures are equipped with an inclinometer, which allows you to measure the height of an object in one step - that is, the hypotenuse and angle are measured, and the height is calculated automatically.

Design and operating principle

The pulse ranging method uses the following ratio:

Where L is the distance to the object,

C – speed of radiation propagation,

T is the time it takes for the impulse to travel to the target and back.

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 pulse reflected by the object reaches the rangefinder, it stops the counter. Based on the time interval (delay of the reflected pulse), the distance to the object is determined.

A rangefinder is a device that is designed to determine the exact distance from an observer to a specific object. The device is simply necessary in engineering geodesy, construction of transmission lines and communications, agriculture, tourism, navigation, military affairs...

Classification of ranging devices

When and where did the first range meters appear? This device first went on sale in 1992 in the West, but its cost reached several thousand dollars. And only four years later these devices became available to a wider range of users. Then many companies began to work in this direction. And today there are quite a few varieties of this instrument, the most accurate ones use the laser principle in their work; a well-known model is the Leica rangefinder; the range also includes other devices for similar purposes, for example, those using lasers.

What is the principle of operation? Active type models measure distance using the time it takes a sent signal to travel to the object and back. The speed with which this signal propagates is, of course, known in advance (sound and light speed). Determining the distance using passive versions of the device is based on calculating the height of an isosceles triangle. Active ones are divided into three types: sound, light, laser. And there are two passive ones: optical and filament.

Active type rangefinders - studying the operation of tools

Sound models measure the distance to objects that reflect sound waves. They work on the principle of an echolocator, that is, first a short sound pulse is emitted, which has a very high frequency. Then the microphone is turned on, and the time is counted during which the sound pulse will return back, reflected from some object. When the returned signal reaches the sensor, the result will be known. Light types of distance measuring devices use light modulation in brightness with a constant or variable frequency.

The distance is calculated by the phase difference between the reflected and sent light. This requires the presence of complex electronic and electrical devices in the device. It was with the help of light models that the exact distance from the Earth to the Moon was established. Laser instruments include the main elements of the device - a reflector and an emitter. Using special function keys, you can set a reference point and use all the software capabilities of the device. Also, some models are equipped with additional functions - a reflective panel for testing, air temperature measurement, selection of a measurement system, automatic shutdown setting, battery indicator.

When working with a laser device, the help of a second person is not required, as, for example, is the case with. In order to calculate the distance to a certain object, you need to point a laser beam at it. The device measures the time it takes for a beam to travel from it to an object and, after being reflected, to return. As a result, calculations are made and the data is displayed on the screen. You can measure both horizontal and vertical planes. Using a laser rangefinder, you can also measure the volume of a room and its total area.

In addition, such a device provides a unique opportunity to measure only a certain fragment of the wall, and not its entirety. You can also define the width and height of an object.

A huge advantage is that the laser device can calculate the average value of several measurements, and the accuracy will be at a very high level. It is also possible to find out the area of round objects, and not just rectangular or square ones. If the room has a sloped ceiling, then the tool will determine not only the area, but also the angle of inclination and the length of the slope. All measurements can be carried out at a distance of up to 200 meters. If you need the device to measure only rooms, it will be enough to purchase a device whose measurement range does not exceed 50 meters. If you are going to work over long distances, you should also use a tripod and a reflective plate, this will allow you to get more accurate results. But not all models can be mounted on a tripod; this needs to be clarified with the seller.

The main characteristics of laser instruments depend not only on the design, for example, the measurement range depends on the power of the radiation source and on external operating conditions, for example, lighting will affect the range. It is worth noting separately that it decreases if measurements are carried out in the open air. Household models have small errors, and these errors increase when measuring over large distances. But even these types of laser devices are relatively expensive.

We measure range using passive methods

Optical rangefinder can be of two types - stereoscopic and monocular. Despite the fact that they differ in the design of the parts, their basic design is the same, in addition, the principles of operation are identical. Using two known angles of a triangle, as well as one known side, its unknown side is determined. Two telescopes construct an image of the object. The object appears to be seen in different directions. In addition, such devices can be either full-field overlay or half-field overlay - the upper half of the image from one telescope is combined with the lower half of the other.

Monocular models are a type of optical, they also work on the principle of combining images, and are very often built into photographic equipment to obtain a sharper image. The advantages of monocular rangefinders are that there is no need for precise horizontal aiming, and the image during measurement is shifted in both the right and left fields. The disadvantages of monocular devices include high fatigue of the operator, since the work is done with one eye, it is also practically impossible to work with moving objects, and the object needs to have a clear generatrix, which is located at ninety degrees to the field dividing line, otherwise the measurement accuracy will decrease significantly.

Stereoscopic models are also a type of optical and have a double telescope. There are marks in the focal plane, and the image of the object is combined with the image of these marks, the distance is completely proportional to the displacement of the compensator. The main advantage of a stereoscopic instrument over a monocular instrument is more accurate distance measurements. They are used to determine the range, as well as the flight altitude and its angular coordinates. The most powerful stereoscopic devices are capable of operating at distances of up to 50,000 meters; as for measuring altitude, the numbers here are slightly smaller - up to 20,000 meters.

The thread version of range finders is the simplest type of instrument for this purpose, having a constant parallax angle, which is why you can make such a range finder with your own hands if you suddenly need to measure the range, but you don’t have time to go shopping, or you’re sorry for the money. It can detect distances up to 300 meters. This device uses a leveling rod with centimeter divisions as a base, and special lines are visible in the field of view of the pipe. How it works: to accurately determine the distance, the number of divisions that are between the lines is counted, and the desired distance will ultimately be the distance in meters. The thread device has a very simple design and a very simple operating principle, it is also able to calculate the distance without much error. But the electronic rangefinder still wins in terms of accuracy.

Good afternoon, dear readers. Today is a review of a useful tool for a shooter - a laser rangefinder, a distance meter up to 600 m.

I continue my series of reviews of air rifle accessories.
There are several types of rangefinders sold in Chinese shops:
Only for golf (optical principle):

Repair meters:

So they are not suitable for shooting. You need a rangefinder with optical targeting, similar to binoculars. This is the model we will consider:

Boring physics. Principle of operation

Measuring range with a hunting laser rangefinder.

Where L is the distance to the object,
- c is the speed of radiation propagation,
- t is the time it takes for the impulse to travel to the target and back.

Packaging, box

I bought it from the TOMTOP store on ebay, directly from their website.

Where a rangefinder can be useful: For shooting, hunting, tourism, sports. I took it for shooting, to accurately determine range corrections in a ballistic calculator.

Characteristics:
Distance measuring range: 5 - 600 m
Angle measurement range: +-60° (for model with index A)
Measuring accuracy: ±1 m
Laser wavelength: 905 nm
Safety Certificate: FDA(CFR 21)
Field of view: 7°
Magnification: 6X
Lens diameter: 24mm
Exit pupil diameter: 3.8mm
Diopter adjustment: ±3 D
Manual focus
Working temperature: 0°~40°
Height measurement
Scan mode
Golf mode
Battery: 3V CR2
Dimensions: 10.5 * 7.5 * 4 cm
Weight: 181 g.

Equipment:
Rangefinder, case, hand strap, cloth for wiping optics, instructions, warranty.

A closer look at the rangefinder itself:

There is a threaded hole for a tripod, a useful addition.

Diopter adjustment occurs by rotating the eyepiece.
This is how it sits in your hand:

Black - soft touch coating to prevent slipping. And of course, it’s better to wear a strap, since the rangefinder is unlikely to survive a fall on the asphalt.

Battery:

Form factor 15270. batteries with charger immediately.

Instructions

Weight with battery and case:

Job:
There are two buttons on top: power and mode, measurement occurs when you press the power button, mode switches modes (in this case, only meters or yards).
We point the crosshair at the desired object - press the button - we see the result in the eyepiece.
Looking into it is almost like looking through a 6x monocular.

Minimum 5 m, maximum 611 I got. At more than 100 m, he aims hard at small objects. Through the glass it takes one at a time.

Indirect accuracy check:

on the map:

To summarize:
I liked the rangefinder itself; I have no complaints about the quality of manufacture and measurements.
But, despite the pictures in the lot, no angle measurement function(I was sent a model without the “A” index). Whether they made a mistake in the store, or whether there was a deliberate deception, I will look into it. I chose a model with a protractor; a model without a protractor can be found cheaper.

Thank you for your attention! Well-aimed shots!

I'm planning to buy +15 Add to favorites I liked the review +22 +36

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