TYPES OF LASER AND ITS APPLICATION IN MODERN

WARFARE

SUBMITTED BY- PRANAY TRIPATHI ( 091221081) VIVEK UPADHYAY(0912210130)

YASHLOK KUMAR DUTT(0912210133)

DEFINATION AND MEANING:LASER stands for ‘ Light amplification by

stimulated emission of radiation’.Light is amplified by a photon which is then

amplified by any external means.LASER is divided into several categories

according to the active medium involved in its production.

TYPES OF LASER:

1.Gas laser2.Solid State laser3.Chemical laser4.Dye laser5.Semi-conductor laser

Gas Laser:

1. A laser in which an electric current is discharged through a gas to produce coherent light.

2. The active medium is gas .3.It operates on the principle of ‘of converting

electrical energy to a laser light output’.4. He-Ne laser is an example .5. Active material is relatively inexpensive.6. Almost impossible to damage the active

material7. Safe as heat can be removed quickly from

the cavity.

Schematic diagram:

Working principle: A tube containing the active gas is placed in an optical

resonator, which in the simplest case consists of two parallel mirrors, one of which is semitransparent. A light wave emitted at any point in the tube is amplified upon propagation through the gas by events of induced emission, which give rise to a photon avalanche. Upon reaching the semitransparent mirror, the wave partially passes through it. This part of the light energy is radiated outward by the gas laser. The other part is reflected from the mirror and gives rise to a new photon avalanche. All the photons are identical in frequency, phase, and direction of propagation. Because of this, laser radiation may have extraordinarily amplification and power and sharp directivity.

Features:1. In comparison with solids and liquids, gases have

a much lower density and higher homogeneity.2.Therefore, a light ray in a gas is virtually not

distorted, does not disperse, and experiences no energy losses. 

3.  As a result, the directivity of the laser radiation is sharply increased , relative to other sources of laser production.

4.The gas has virtually no effect on the propagation of radiation in the cavity, hence the stability of the radiation frequency of a gas laser depends primarily on the immobility of the mirrors and the entire structure of the resonator. 

5.Sees application in manufacturing industries etc.

Solid State Laser:1.Solid-state lasers are lasers based on solid-state gain

media such as crystals or glasses doped with rare earth or transition metal ions, or semiconductor lasers.

2.Although semiconductor lasers are of course also solid-state devices, they are often not included in the term solid-state lasers.

3. Solid-state lasers may generate output powers between a few milliwatts and (in high-power versions) many kilowatts. 

4. Many solid-state lasers are optically pumped with flash lamps or arc lamps as they are cheap and can provide very high power.

5. The most famous example of solid state laser is ruby laser.

Schematic diagram:

Working principle:The active medium ( in case of ruby laser)

ruby crystal is kept between the helical flash lamp which is used to provide flashes of light ( optical pumping) which excites the atom in the ground state, providing them the threshold energy to reach the excited state an then to the meta stable state. The arrangement is kept between the optical cavity .The amplified light by stimulated emission provided by the lasing photon escapes through the partially reflective mirror.

Features:1. The long upper-state( the meta stable

state) lifetimes makes solid-state lasers very suitable for the production of high energy pulsated laser beam.

2.The solid crystals are capable of storing an amount of energy which, when released can lead to  peak power which is orders of magnitude above the achievable average power.  

3.The amplification increases or decreases depending on the doping.

Chemical laser:1. A Chemical laser  is a laser that obtains

its energy from a chemical reaction.2. It can achieve continuous wave output with

power reaching to megawatt levels.3. Common examples of chemical lasers are

the chemical oxygen iodine laser (COIL), all gas-phase iodine laser (AGIL), and the hydrogen fluoride laser and deuterium fluoride laser.

Schematic diagram:

Dye laser:

1. A dye laser is a laser based on a dye (in a liquid solution or in solid form) as the gain medium.

2. A wide range of emission wavelengths from the ultraviolet to the near-infrared region can be addressed with different laser dyes.

Schematic diagram:

Working principle:Solution of dye( organic solvent ) is kept in

the place of active medium, like any other laser.

The molecules ( atoms) under the effect of external pump light get excited and emit light , which when kept in the resonator produces lasers.

Semi conductor laser:A semiconductor laser converts electrical energy into light.

This is made possible by using a semiconductor material, whose ability to conduct electricity is between that of conductors and insulators.

The number of negatively charged electrons or positively charged holes can be changed by doping the semiconductor with impurities.

Schematic diagram:

Working principle:The laser operation occurs at a p-n junction,

that is the boundary region between p-type and n-type materials.

Features:

The semiconductor laser is similar to a transistor or to a semiconductor diode.

Semiconductor lasers are compact, reliable and last a long time.

Smallness in size makes them excellent in fabrication.

Array of semiconductor bar can produce power up to 5 kilowatt.

Modern warfare:

Modern warfare:1.Given their high amplification , unidirectional

, penetrating power and intensity lasers can be an excellent tool in modern warfare.

2.Laser can be used to destroy enemies fighter planes , drowning aircraft carriers and providing an excellent and efficient replacement for anti-aircraft and anti-missile technology.

3.Pulsated generation of laser ( property of solid state lasers) can be used as a fuel and rocket propulsion system.

1.Amplified light in modern warfare started with Galileo.

2.The concept of laser was introduced in early 20th century by Einstein.

In the year 1957,first laser was developed.George Lucas in his 1975 classic “ Star wars:

a new hope” introduced the idea of laser in modern warfare . It marked the beginning of laser in modern warfare.

History:

.

1. American cabinet released the amount of 5 million USD for the project “Annihilation” in the year 1970 which was primarily based on developing lasers as a feasible , efficient and yet powerful weapon.

2. After more than four decades of doggedly pursuing the elusive technology, engineers working in at least three laboratories around the Southland , America have been quietly developing high-powered, solid-state laser that some defense analysts say could revolutionize warfare. 

Turning a fantasy into reality, Southern California defense companies are on the verge of building a laser weapon small enough to fit on a fighter jet, yet powerful enough to destroy an enemy aircraft at the blink of an eye. 

A Navy ship could use the laser, with its beam traveling at the speed of light, to fend off even the fastest missiles. And ground troops could use a Humvee-mounted version of the weapon to instantly knock out incoming enemy artillery and mortar shells. 

The holy grail:

Research in solid-state lasers received a major boost when the Pentagon quietly launched a $50-million initiative to develop a 25-kilowatt laser by the end of 2004, with the goal of deploying by the end of the decade a 100-kilowatt laser that could be installed on warplanes, tanks and ships. 

The most powerful laser currently is a 10-kilowatt model that is being tested by the Army. 

Information about the damage such lasers could inflict is classified. But in general, experts say, a 25-kilowatt laser could blind an enemy sensor several hundred miles away. It also could put a hole through a sheet of metal from a distance of several miles. 

How we are gonna use it?

A laser's beam would not by itself cause a target to explode. But it could slice through the outer casing of a missile, disabling the guidance system or causing the missile's propellant to explode. 

What we can expect?It's not clear how much the Pentagon has spent

developing a laser weapon, but an Air Force official last summer said that his service alone had poured $4.5 billion into direct-energy weapons, which include microwave and chemical laser technologies. 

Over time, solid-state lasers will become more powerful and more compact, which will make them more useful on the battlefield and perhaps revolutionize the conduct of war," said Loren B. Thompson, chief operations officer for Lexington Institute( a prime institute in laser tech), a defense think tank. 

It may be possible to scale down the chemical laser to fit on a fighter jet or an armored vehicle, but it could take decades to perfect the technology.

No doubt that by the end of the decade, we will have a laser weapon installed on a Joint Strike Fighter jet or an AC-130 gunship. 

Facts:

•Last year, a "Laser Avenger" mounted aboard a truck shot down unmanned aerial vehicles in tests at White Sands Missile Range in New Mexico.

•In October, a laser-equipped U.S. Air Force "Advanced Tactical Laser" C-130 airplane burned a hole in a slow-moving vehicle during a test at White Sands.

•The Pentagon's Defense Advanced Research Projects Agency (DARPA) signaled plans last year to develop a plane-mounted 150-kilowatt, 1,650-pound laser to knock down rockets and artillery shells in flight. Tests pointed to success shooting down mortar shells, the U.S. Army said.

•Not a weapon but a weapon tester, the Energy Department's National Ignition Facility is using the world's most powerful laser to simulate hydrogen bomb blasts on nuclear material.

In 2008, a National Research Council Report called for the U.S. Army to speed development of a $470 million "mobile, 100,000-watt solid-state laser weapon system" to knock down mortar shells and rockets by 2018. The 100-kilowatt laser was demonstrated by Northrop in May last year. But it required a tractor-trailer-sized laser, Weinberger notes, not something that a Humvee could carry.

Are there any other uses?Yes……eventually Defense News reported in

2006 that China had illuminated a U.S. imaging satellite with a laser, potentially damaging the sensitive optics aboard the spacecraft. 

About 40 "Satellite Laser Ranging" stations worldwide use laser pulses aimed at satellites to time how long it takes the light to return to Earth, which can answer questions about the planet's gravity and reveal satellites' orbits, important to know if you plan to hide activities from spy satellites.

With drones being used more frequently to spy on or attack fleets in future warfare it is necessary to make defences against them. The laser system, which is mostly situated under the deck, fires an invisible beam that is only seen when it strikes an intruder. The system is also being developed to tackle small boats and potentially anti-ship missiles and will be ready for full military development by 2016. 

Is it all about destruction?No ………….Laser based propulsion system.NASA plans to deploy laser based propulsion

system by the year 2025.

To improve the performance of rocket engines is to separate the energy source from the rocket.

This can be accomplished by using a laser beam to transfer energy from a stationary source to the rocket.

In laser propulsion, the rocket carries a tank of reaction mass, but a stationary laser supplies the energy.

  Laser-thermal propulsion. Laser-supported detonation.

What is India’s scenario?Lasers?? In warfare??India has seen astonishing increment of 19%

in total expenditure in the budget over the last decade but primarily on developing large range missile and importing technology from USA and gulf countries.

Way behind in applying laser in warfare.