LASERS:AN ADVANCED TECHNIQUE AND ITS APPLICATION
INTRODUCTION
In modern era,there are many techniques which bring a revolution in manâ„¢s life.whether it is a field of science, medical etc.One of the majoruseful techniques(which is being used in every aspects of life)LASER which is an acronym for LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION.This is the device which proved to be boon for human life. LASER, invented in 1960 by Gordon Gould had the battle of his life receiving credit for his laser invention. It is a device by which an intense ,monochromatic ,collimated and highly coherent light beam can be obtained.
HISTORY OF LASERS:
The history of the laser began with a little boy and an Erector set. A little boy by the name of Gordon Gould was the son of Kenneth Miller and Helen Gould. He was born in New York City on July 17, 1920. The Erector set is a construction kit that children use to put things together and take them apart. After watching his mother use the set to construct various things, Gordon began to construct things himself and take them apart. So this was the beginning of taking things apart and fixing them for a creative child. With the help of his brothers, he began to take clocks apart piece-by-piece and attempt to fix them.
Then it happened in 1973 when he won his first court victory. The courts decided the documentation for the laser provided by Townes and Schawlow did not reflect the instructions for building a laser. Good news was heard in October of 1977. Gouldâ„¢s optic pump was finally given a patent. The good news did not stop with the optic pump. The United States Patent Office Appeals Board overturned all objections in 1986. This is something that Gould had been waiting to hear for years. Gould was 67 years old and his dream was finally coming true.
History was made with Gouldâ„¢s invention of the laser and the world reaps its benefits almost every day. Lasers can measure the distance to the moon and are being used in communications. The Universal Product Code we see on items is associated with the laser. The laser is responsible for compact disks, which contain recorded sound. Gould will be remembered as the inventor who was the most influential in the 20th century.
In order to understand the basics of LASERS , following terms should be known which are as follows:-
STIMULATED AND SPONTANEOUS EMISSION
Three kinds of transitions involving electromagnetic radiation are possible between two energy levels,Eo and E1,in an atom (fig a).If the atom is initially in the lower state Eo,it can be raised to E1 by absorbing aphoton of energy E1-Eo =hv.This process is called stimulated emission.If the atom is initially in upper state E1,it can drop to Eo by emitting a photon of energy hv. This is spontaneous emission.
Einstein, in1917,was the first to point out a third possibility, stimulated emission,in which an incident photon of energy hv causes transitionfrom E1 to Eo .In stimulated emission, the radiated light waves are exactly in phase with the incident ones, so the result is an enhanced beam of coherent light. Einstein showed that stimulated emission has the same probability as stimulated absorption . That is ,a photon of energy hv incident on an atom in the upper state E1 has the same likelihood of causing the emission of another photon of energy hv as its likelihood of being absorbed if it is incident on atom in the lower state Eo.
He introduced stimulated emission and used it to arrive at the form of Planckâ„¢s radiation law in an elegantly simple manner . By the early 1920s this idea together with what had becomeknown about the physics of the atom would have enabled the laser to have beeen invented then ,but ,somehow nobody connected the dots until over 30 years.
MATHEMATICAL FORMULATION:-
Consider two energy states ina particular atom, alower one i and an upper one j (fig b).If the atom is initially in state i ,it can be raised to state j by absorbing a photon of frequency
V = Ej “Ei / h ¦¦¦. (1)
Now imagine an assembly of Ni atoms in state i and Nj atoms in j state,all in thermal equillibrium at the temperature T with light of frequency v and energy density u(v),The probability that an atom in state I absorbs aphoton is proportional to the energy densityu(v) and
also to the properties of states i and j ,which can include in some constant Bij .Hence the number Ni->j of atoms per second that absorb photons is given by Number of atoms that absorb photons Ni->j =Nbij u(v) ¦¦¦..(2)
An atom in the upper state j has a certain probability Aij to spontaneously drop to state i by emitting a photon of frequency v . Also a photon frequency v can somehow interact with an atom in state j to induce its transition to the lower state I .An energy density of u(v) therefore means a probability for stimulated emission of Bij u(v),where Bij ,like Bij and Aij, depends on the properties of states i and j. Since Nj is the number of atoms per seconds that fall to lower state i is
Number of atoms that emit photons
Ni->j = Nj [ Aij + Bij u(v) ] ¦¦¦¦¦(3)
Stimulated emission has a classical physics analog in the behaviour of a harmonic oscillator. Of course, classical physics often doesnot apply on atomic scale ,but it is not assumed that stimulated emission does occur, only that it may occur. If this assumption is wrong , ultimately it is found that Bij = 0.
Since the system here is in equillibrium ,the number of atoms per seconds that go from state i to j must equal the number that go from j to i. Therefore
Ni->j =Nj->i
Ni Bij u(v) = Nj [ Aji + Bji u(v) ]
Dividing both side of the latter equation by Nj Bji and solving for u(v) gives
(Ni/ Nj) (Bij /Bji) u(v) = Aji / Bji + u(v)
u(v) = Aji/Bji /(Ni/ Nj) (Bij /Bji -1 ¦¦¦¦¦¦¦¦¦.(4)
Finally ,the numbers of atoms of energies Ei and Ej in a system of these atoms at the temperature T, which can be written as
_Ei/ kt
Ni = C e
_Ej/kt
Nj = Ce
Hence _( Ei “ Ej) /kt ( Ej “ Ei ) /kt hv/ kt
Ni/Nj = e = e = e (from eq 1) ¦¦¦(5)
And so hv/ kt
u(v) = Aji / (Bij / Bji )e -1 ¦¦¦¦¦¦¦¦¦¦.(6)
This formula gives the energy density of photons of frequency v in equillibrium at the temperature T with atoms whose possible energies are Ei and Ej .
Equation (6) is consistent with the Planck radiation law of Eq if
Bij = Bji
And
Aji / Bji = 8phv3 / c3 ¦¦¦¦¦¦¦¦¦¦¦(7)
Following conclusions can be drawn :
1. Stimulated emission does occur and its probability for a transition between two states is equal to the probability for absor ption.
2. The ratio between the probabilities for spontaneous and stimulated emission varies with v3 ,so the relative likelihood of spontaneous emission increases rapidly with the energy difference between two states .
Spontaneous emission and stimulated emission differ in an important respect. Spontaneous emission is a completely random process , and the emitted photons are in coherent , which means that their phases and propagation direction are random .In stimulated emission, the phase and direction of propagation are the same as that of the incident photon. This is referred as coherent photon emission . A light bulb is an incoherent photon source.The phase relation between individual photons is random , and because the propagation direction the photons is random ,the intensity of the source falls off as the square of the distance. A LASER is a coherent source of radiation. All photons are in phase ,and because they have the same propagation direction ,the divergence of the beam is very small. This explains why laser beam that is reflected from the moon still has a measurable intensity when it returns to earth .
POPULATION INVERSION:
It describes an assembly of atoms in which the majority are in energy levels above the ground state ,normaly the ground state is occupied to the greatest extent.
A number of ways exist to produce a population inversion .One of them, called optical pumping illustrated in (fig ).Here an external light source is used some of whose photons have the right frequency to raise ground state atoms to the excited state that decays spontaneously to the desired metastable state.
PRINCIPLE AND WORKING :
In order for a laser to function properly, more atoms with stored energy must be present than atoms with free storage space, as more photons on average would otherwise be absorbed than the number of new ones being added. This state is known as inversion. In order to achieve this state, atoms are kept in an excited state by pumping the laser, and some photons are inserted. This causes some atoms to undergo stimulated emission, and the resulting photons cause other atoms to undergo stimulated emission, leading to a chain reaction.
To make some of the photons pass through the laser medium more than once, a so-called resonator is used: Two mirrors are positioned to reflect and amplify the light between them before it leaves the laser as the output beam. One mirror is almost perfectly reflective and the second reflects only most of the incoming photons, allowing some of the photons to pass through it. This forms the laser beam.
Fig( ) :The principal of the laser
WORKING PRINCIPLE :
Two coherent laser beams derived from a single source intersect at a fixed angle. The intersection volume of the two beams is positioned on the sample surface. The wavefronts of the two beams interfere in the intersection volume and form an interference pattern. The fringes of the pattern have a known distance depending on the wavelength of the laser and the angle between the two beams.
For simplicity, assume that an element with a velocity component perpendicular to the center axis is moving through the intersection volume. The element will scatter light with its amplitude modulated by the local intensity contrast. The frequency of the modulation is proportional to the velocity of the element.
Thus when recording the intensity signal the motion of elements within the observation area can be calculated. A typical sample with its natural roughness contains scattering elements everywhere on its surface which allows the measurement of the amount of material moving through the observation area.
By simultaneous measurement at two points of the sample surface the relative motion between these two points can be determined. This allows the use of the measuring arrangement as an extensometer.
In other words , principle at which laser works can be understood as the no atoms of a substance are in their ground state .When they are given energyu by some external source,they are excited and reach some higher energy state.An atom can persist in an excited state only for 10n (n = -8 ) seconds after which it returns to its original state. In this process, the atom emits light photons of frequency v ,where
hv = E2 - E1
where E2 and E1 are the energies in the higher and the lower energy states respectively.The
process called spontaneous emission . This ian irregular emission and takes place at different times for different atoms. So, the light obtained by spontaneous emmission from different atoms is incoherent.
If ,however ,when an atom is in an excited state E2,alight photon of the same frequency which is to be emitted by the atom ,falls upon it,then the atom immediately comes down to its normal state E1 and estimulates the incident light by emitting the photon of exactly the same frequency.this is called as stimulated emission which is completely coherent with the incident light.Now the stimulated and the incident light photons cause coherent stimulated light emission from the excited atoms.If the substance has a good number of excited atoms ,then this process gets multiplied . Thus, an intense ,coherent light beam is emitted from the substance.
TYPES OF LASERS
According to their sources:
1. Gas Lasers
2. Crystal Lasers
3. Semiconductors Lasers
4. Liquid Lasers
¢ According to the nature of emission:
1. Continuous Wave
2. Pulsed Laser
¢ According to their wavelength:
1. Visible Region
2. Infrared Region
3. Ultraviolet Region
4. Microwave Region
5. X-Ray Region
INSTRUMENTATION OF RUBY LASERS
A laser is constructed from three principal parts:
¢ An energy source (usually referred to as the pump or pump source),
¢ A gain medium or laser medium, and
¢ Two or more mirrors that form an optical resonator.
Pump source
The pump source is the part that provides energy to the laser system. Examples of pump sources include electrical discharges, flashlamps, arc lamps, light from another laser, chemical reactions and even explosive devices. The type of pump source used principally depends on the gain medium, and this also determines how the energy is transmitted to the medium. A helium-neon (HeNe) laser uses an electrical discharge in the helium-neon gas mixture, a Nd:YAG laser uses either light focused from a xenon flash lamp or diode lasers, and excimer lasers use a chemical reaction.
Gain medium / Laser medium
The gain medium is the major determining factor of the wavelength of operation, and other properties, of the laser. There are hundreds if not thousands of different gain media in which laser operation has been achieved. The gain medium is excited by the pump source to produce a population inversion, and it is in the gain medium that spontaneous and stimulated emission of photons takes place, leading to the phenomenon of optical gain, or amplification.
Examples of different gain media include:
¢ Liquids, such as dye lasers. These are usually organic chemical solvents, such as methanol, ethanol or ethylene glycol, to which are added chemical dyes such as coumarin, rhodamine and fluorescein. The exact chemical configuration of the dye molecules determines the operation wavelength of the dye laser.
¢ Gases, such as carbon dioxide, argon, krypton and mixtures such as helium-neon. These lasers are often pumped by electrical discharge.
¢ Solids, such as crystals and glasses. The solid host materials are usually doped with an impurity such as chromium, neodymium, erbium or titanium ions. Typical hosts include YAG (yttrium aluminium garnet), YLF (yttrium lithium fluoride), sapphire (aluminium oxide) and various glasses. Examples of solid-state laser media include Nd:YAG, Ti
apphire, Cr
apphire (usually known as ruby), Cr:LiSAF (chromium-doped lithium strontium aluminium fluoride), Er:YLF, Nd:glass, and Er:glass. Solid-state lasers are usually pumped by flashlamps or light from another laser.
¢ Semiconductors, a type of solid, in which the movement of electrons between material with differing dopant levels can cause laser action. Semiconductor lasers are typically very small, and can be pumped with a simple electric current, enabling them to be used in consumer devices such as compact disc players. See laser diode.
Optical resonator
The optical resonator, or optical cavity, in its simplest form is two parallel mirrors placed around the gain medium which provide feedback of the light. The mirrors are given optical coatings which determine their reflective properties. Typically one will be a high reflector, and the other will be a partial reflector. The latter is called the output coupler, because it allows some of the light to leave the cavity to produce the laser's output beam.
Light from the medium, produced by spontaneous emission, is reflected by the mirrors back into the medium, where it may be amplified by stimulated emission. The light may reflect from the mirrors and thus pass through the gain medium many hundreds of times before exiting the cavity. In more complex lasers, configurations with four or more mirrors forming the cavity are used. The design and alignment of the mirrors with respect to the medium is crucial to determining the exact operating wavelength and other attributes of the laser system.
Other optical devices, such as spinning mirrors, modulators, filters, and absorbers, may be placed within the optical resonator to produce a variety of effects on the laser output, such as altering the wavelength of operation or the production of pulses of laser light.
Some lasers do not use an optical cavity, but instead rely on very high optical gain to produce significant amplified spontaneous emission (ASE) without needing feedback of the light back into the gain medium. Such lasers are said to be superluminescent, and emit light with low coherence but high bandwidth. Since they do not use optical feedback, these devices are often not categorized as lasers.
Characteristics of Laser
1. Highly Monochromatic:
* Laser ray is highly pure beam of light with respect to the wavelength and the frequency of the photons forming it.
2. Highly Directional
* laser beam is highly intense and very narrow beam this is because its divergence is very small.
* Laser beam transfers in straight lines approximately parallel to each other.
3. Highly Coherent
* The laser photons are coherent,in phase and have the same direction.
APPLICATIONS OF LASERS:
There are many scientific, military, medical and commercial laser applications which have been developed since the invention of the laser in the 1958. The coherency, high monochromaticity, and ability to reach extremely high powers are all properties which allow for these specialized applications.
Scientific
In science, lasers are used in many ways, including:
¢ A wide variety of interferometric techniques
¢ Raman spectroscopy
¢ Laser induced breakdown spectroscopy.
¢ Atmospheric remote sensing
¢ Investigating nonlinear optics phenomena
¢ Holographic techniques employing lasers also contribute to a number of measurement techniques.
¢ Laser based LIght Detection And Ranging (LIDAR) technology has application in geology, seismology, remote sensing and atmospheric physics.
¢ Lasers have been used aboard spacecraft such as in the Cassini-Huygens mission.
¢ In astronomy, lasers have been used to create artificial laser guide stars, used as reference objects for adaptive optics telescopes.
Lasers may also be indirectly used in spectroscopy as a micro-sampling system, a technique termed Laser ablation (LA), which is typically applied to ICP-MS apparatus resulting in the powerful LA-ICP-MS.
The principles of laser spectroscopy are discussed by Demtröder[1] and the use of tunable lasers in spectroscopy are described in Tunable Laser Applications.[2]
Spectroscopy
Most types of laser are an inherently pure source of light; they emit near-monochromatic light with a very well defined range of wavelengths. By careful design of the laser components, the purity of the laser light (measured as the "linewidth") can be improved more than the purity of any other light source. This makes the laser a very useful source for spectroscopy. The high intensity of light that can be achieved in a small, well collimated beam can also be used to induce a nonlinear optical effect in a sample, which makes techniques such as Raman spectroscopy possible. Other spectroscopic techniques based on lasers can be used to make extremely sensitive detectors of various molecules, able to measure molecular concentrations in the parts-per-trillion (ppt) level. Due to the high power densities achievable by lasers, beam-induced atomic emission is possible: this technique is termed Laser induced breakdown spectroscopy (LIBS).
Lunar laser ranging
Main article: Lunar laser ranging experiment
When the Apollo astronauts visited the moon, they planted retroreflector arrays to make possible the Lunar Laser Ranging Experiment. Laser beams are focused through large telescopes on Earth aimed toward the arrays, and the time taken for the beam to be reflected back to Earth measured to determine the distance between the Earth and Moon with high accuracy.
Material processing
Laser cutting, laser welding, laser brazing, laser bending, laser engraving or marking, laser cleaning, weapons etc. LIA has edited a book on most of these topics: "Handbook of Laser Materials Processing".
Photochemistry
Some laser systems, through the process of modelocking, can produce extremely brief pulses of light - as short as picoseconds or femtoseconds (10-12 - 10-15 seconds). Such pulses can be used to initiate and analyse chemical reactions, a technique known as photochemistry. The short pulses can be used to probe the process of the reaction at a very high temporal resolution, allowing the detection of short-lived intermediate molecules. This method is particularly useful in biochemistry, where it is used to analyse details of protein folding and function.
Laser cooling
A technique that has had recent success is laser cooling. This involves atom trapping, a method where a number of atoms are confined in a specially shaped arrangement of electric and magnetic fields. Shining particular wavelengths of laser light at the ions or atoms slows them down, thus cooling them. As this process is continued, they all are slowed and have the same energy level, forming an unusual arrangement of matter known as a Bose-Einstein condensate.
Nuclear fusion
Some of the world's most powerful and complex arrangements of multiple lasers and optical amplifiers are used to produce extremely high intensity pulses of light of extremely short duration. These pulses are arranged such that they impact pellets of tritium-deuterium simultaneously from all directions, hoping that the squeezing effect of the impacts will induce atomic fusion in the pellets. This technique, known as "inertial confinement fusion", so far has not been able to achieve "breakeven", that is, so far the fusion reaction generates less power than is used to power the lasers, but research continues.
Microscopy
Confocal laser scanning microscopy and Two-photon excitation microscopy make use of lasers to obtain blur-free images of thick specimens at various depths. Laser capture microdissection use lasers to procure specific cell populations from a tissue section under microscopic visualization.
Additional laser microscopy techniques include harmonic microscopy, four-wave mixing microscopy[3] and interferometric microscopy.[4]
Military
Military uses of lasers include applications such as target designation and ranging, defensive countermeasures, communications and directed energy weapons. Directed energy weapons such as Boeingâ„¢s Airborne Laser which can be built inside a 747 jet can burn the skin off enemy missiles.[5]
On March 18, 2009 Northrop Grumman announced that its engineers in Redondo Beach had successfully built and tested an electric laser capable of producing a 100-kilowatt ray of light, powerful enough to destroy cruise missiles, artillery, rockets and mortar rounds.[6] An electric laser is theoretically capable, according to Brian Strickland, manager for the United States Army's Joint High Power Solid State Laser program, of being mounted in an aircraft, ship, or vehicle because it requires much less space for its supporting equipment than a chemical laser.[7]
Defensive countermeasures
Defensive countermeasure applications can range from compact, low power infrared countermeasures to high power, airborne laser systems. IR countermeasure systems use lasers to confuse the seeker heads on heat-seeking anti-aircraft missiles. High power boost-phase intercept laser systems use a complex system of lasers to find, track and destroy intercontinental ballistic missiles (ICBM). In this type of system a chemical laser, one in which the laser operation is powered by an energetic chemical reaction, is used as the main weapon beam (see Airborne Laser). The Mobile Tactical High-Energy Laser (MTHEL) is another defensive laser system under development; this is envisioned as a field-deployable weapon system able to track incoming artillery projectiles and cruise missiles by radar and destroy them with a powerful deuterium fluoride laser.
Another example of direct use of a laser as a defensive weapon was researched for the Strategic Defense Initiative (SDI, nicknamed "Star Wars"), and its successor programs. This project would use ground-based or space-based laser systems to destroy incoming intercontinental ballistic missiles (ICBMs). The practical problems of using and aiming these systems were many; particularly the problem of destroying ICBMs at the most opportune moment, the boost phase just after launch. This would involve directing a laser through a large distance in the atmosphere, which, due to optical scattering and refraction, would bend and distort the laser beam, complicating the aiming of the laser and reducing its efficiency.
Another idea to come from the SDI project was the nuclear-pumped X-ray laser. This was essentially an orbiting atomic bomb, surrounded by laser media in the form of glass rods; when the bomb exploded, the rods would be bombarded with highly-energetic gamma-ray photons, causing spontaneous and stimulated emission of X-ray photons in the atoms making up the rods. This would lead to optical amplification of the X-ray photons, producing an X-ray laser beam that would be minimally affected by atmospheric distortion and capable of destroying ICBMs in flight. The X-ray laser would be a strictly one-shot device, destroying itself on activation. Some initial tests of this concept were performed with underground nuclear testing; however, the results were not encouraging. Research into this approach to missile defense was discontinued after the SDI program was cancelled.
Targeting
Target designator
Main article: Laser designator
A target designator
Another military use of lasers is as a laser target designator. This is a low-power laser pointer used to indicate a target for a precision-guided munition, typically launched from an aircraft. The guided munition adjusts its flight-path to home in to the laser light reflected by the target, enabling a great precision in aiming. The beam of the laser target designator is set to a pulse rate that matches that set on the guided munition to ensure munitions strike their designated targets and do not follow other laser beams which may be in use in the area. The laser designator can be shone onto the target by an aircraft or nearby infantry. Lasers used for this purpose are usually infrared lasers, so the enemy cannot easily detect the guiding laser light.
Firearms
Laser sight
Smith & Wesson revolver equipped with laser sight mounted on trigger guard.
The laser has in most firearms applications been used as a tool to enhance the targeting of other weapon systems. For example, a laser sight is a small, usually visible-light laser placed on a handgun or a rifle and aligned to emit a beam parallel to the barrel. Since a laser beam by definition has low divergence, the laser light appears as a small spot even at long distances; the user places the spot on the desired target and the barrel of the gun is aligned (but not necessarily allowing for bullet drop, windage and the target moving while the bullet travels).
Most laser sights use a red laser diode. Others use an infrared diode to produce a dot invisible to the naked human eye but detectable with night vision devices. The firearms adaptive target acquisition module LLM01 laser light module combines visible and infrared laser diodes. In the late 1990s, green diode pumped solid state laser (DPSS) laser sights (532 nm) became available. Modern laser sights are small and light enough for attachment to the firearms.
In 2007, LaserMax, a company specializing in manufacturing lasers for military and police firearms, introduced the first mass-production green laser available for small arms. This laser mounts to the underside of a handgun or long arm on the accessory rail. The green laser is supposed to be more visible than the red laser in bright lighting conditions because, for the same wattage, green light appears brighter than red light.
Eye-targeted lasers
A non-lethal laser weapon was developed by the U.S. Air Force to temporarily impair an adversaryâ„¢s ability to fire a weapon or to otherwise threaten enemy forces. This unit illuminates an opponent with harmless low-power laser light and can have the effect of dazzling or disorienting the subject or causing him to flee. Several types of dazzlers are now available, and some have been used in combat.
There remains the possibility of using lasers to blind, since this requires much lower power levels, and is easily achievable in a man-portable unit. However, most nations regard the deliberate permanent blinding of the enemy as forbidden by the rules of war . Although several nations have developed blinding laser weapons, such as China's ZM-87, none of these are believed to have made it past the prototype stage.
In addition to the applications that crossover with military applications, a widely known law enforcement use of lasers is for lidar to measure the speed of vehicles.
Medical
See also: laser medicine
¢ Cosmetic surgery (removing tattoos, scars, stretch marks, sunspots, wrinkles, birthmarks, and hairs): see laser hair removal. Laser types used in dermatology include ruby (694 nm), alexandrite (755 nm), pulsed diode array (810 nm), Nd:YAG (1064 nm), Ho:YAG (209|Er]]:YAG (2940 nm).
¢ Eye surgery and refractive surgery
¢ Soft tissue surgery: CO2, Er:YAG laser
¢ Laser scalpel (General surgery, gynecological, urology, laparoscopic)
¢ Photobiomodulation (i.e. laser therapy)
¢ "No-Touch" removal of tumors, especially of the brain and spinal cord.
¢ In dentistry for caries removal, endodontic/periodontic procedures, tooth whitening, and oral surgery
Industrial and commercial
Lasers used for visual effects during a musical performance. (A laser light show.)
¢ Cutting and peening of metals and other material, welding, marking, etc
¢ Guidance systems (e.g., ring laser gyroscopes)
¢ Rangefinder / surveying,
¢ LIDAR / pollution monitoring,
¢ Digital minilabs
¢ Barcode readers
¢ Laser engraving of printing plate
¢ Laser bonding of additive marking materials for decoration and identification,
¢ Laser pointers
¢ Laser accelerometers
¢ Holography
¢ Bubblegrams
¢ Photolithography
¢ Optical communications (over optical fiber or in free space)
¢ Optical tweezers
¢ Writing subtitles onto motion picture films.[9]
¢ Space elevator, a possible solution transfer energy to the climbers by laser or microwave power beaming
¢ 3D laser scanners for accurate 3D measurement.
¢ Laser line levels are used in surveying and construction. Lasers are also used for guidance for aircraft.
¢ Extensively in both consumer and industrial imaging equipment.
¢ In laser printers: gas and diode lasers play a key role in manufacturing high resolution printing plates and in image scanning equipment.
¢ Diode lasers are used as a lightswitch in industry, with a laser beam and a receiver which will switch on or off when the beam is interrupted, and because a laser can keep the light intensity over larger distances than a normal light, and is more precise than a normal light it can be used for product detection in automated production.
¢ Laser alignment
¢ Additive manufacturing
In consumer electronics, telecommunications, and data communications, lasers are used as the transmitters in optical communications over optical fiber and free space.
¢ To store and retrieve data in optical discs
¢ Laser lighting displays (pictured) accompany many music concerts.