LASERMore Than You Know

Somya Tyagi – 10th Socrates

Table Of Contents

IntroductionThe BasicsAbsorbing EnergyThe Laser/Atom ConnectionLaser LightHow does Laser differ from Other Light?Types Of LaserApplications Of LaserEveryday ApplicationsBibliography

LASER is an acronym for L = LightA = AmplificationS = by StimulatedE = EmissionR = of Radiation Almost everyone probably knows that the police use

laser when they measure speed, but how many know that you also use laser several times during an ordinary day? You'll find it in CD players, laser printers and much, much more.

The power contained in laser is both fascinating and frightening.

Atoms are constantly in motion. They continuously vibrate, move and rotate.

Atoms can be in different states of excitation, i.e., they can have different energies.

Apply a lot of energy to an atom, it can leave what is called the ground-state energy level and go to an excited level.

This reflects the core idea of how atoms work in terms of lasers.

Once an electron moves to a higher-energy orbit, it eventually wants to return to the ground state.

When it does, it releases its energy as a photon -- a particle of light.

For example, when the heating element in a toaster turns bright red, the red colour is caused by atoms, excited by heat, releasing red photons. When you see a picture on a TV screen, what you are seeing is atoms, excited by high-speed electrons, emitting different colours of light. Anything that produces light -- fluorescent lights, gas lanterns, incandescent bulbs -- does it through the action of electrons changing orbits and releasing photons.

The Laser/Atom The Laser/Atom ConnectionConnection A laser is a device that controls the way

that energized atoms release photons. "Laser" is an acronym for light amplification by stimulated emission of radiation, which describes very succinctly how a laser works.

In a laser, the lasing medium is “pumped” to get the atoms into an excited state.

The electron absorb some energy to reach this excited level and then release this energy.

The Laser/Atom The Laser/Atom ConnectionConnection This emitted energy comes in

the form of photons (light energy).

The photon emitted has a very specific wavelength (colour) that depends on the state of the electron's energy when the photon is released.

Laser Light Laser light has the following properties:1. The light released is monochromatic. It

contains one specific wavelength of light (one specific colour).

2. The light released is coherent. It is “organized” -- each photon moves in step with the others.

3. The light is very directional. A laser light has a very tight beam and is very strong and concentrated.

To make these three properties occur takes something called stimulated emission.

How Does Laser Light Differ from Other Light?

Light is an electromagnetic wave.Each wave has brightness and colour,

and vibrates at a certain angle. This is also true for laser light but it is

more parallel than any other light source.

Every part of the beam has (almost) the exact same direction and the beam will therefore diverge very little.

TYPES OF LASERS Solid-state lasers have lasing material

distributed in a solid matrix Gas lasers (helium and helium-neon, are the

most common gas lasers) have a primary output of visible red light. CO2 lasers are used for cutting hard materials.

Excimer lasers (the name is derived from the terms excited and dimers) use reactive gases, such as chlorine and fluorine, mixed with inert gases such as argon, krypton or xenon. When electrically stimulated dimer is produced. When lased, the dimer produces light in the ultraviolet range.

TYPES OF LASERS

Dye lasers use complex organic dyes in liquid solution or suspension as lasing media.

Semiconductor lasers, sometimes called diode lasers, are not solid-state lasers. They may be built into larger arrays, such as the writing source in some laser printers or CD players.

Applications Of LASERS1.Industrial Applications of Laser : ₪ Laser can be found in a broad range of

applications within industry, where it can be used for such things as pointing and measuring.

₪ Within the pulp mill industry the concentration of lye is measured by observing how the laser beam refracts in it.

₪ In the mining industry, laser is used to point out the drilling direction.

Applications Of LASERS2. Environmental Applicationsᴥ Usage to determine from a distance the

environmental toxins in a column of smoke.ᴥ To supervise wastewater purification.

Applications Of LASERS3. ResearchExtremely important to researchers within physics,

chemistry, biology and medicine, used to: register ultra fast chemical processes, like-bonding

between atoms to form molecules study the process when cells split, or a virus enters

into a cell manipulate molecules down to extremely low

temperatures; transfer as much energy as possible to different

materials in a short time to obtain different types of emissions.

Applications Of LASERS4. CommunicationsѺ Works as a light source in all fibre optics in use. Ѻ Has greater bandwidth (potentially 100,000

times greater) than an ordinary copper cable.Ѻ Is insensitive to interference from external

electrical and magnetic fields. Ѻ Crosstalk (hearing someone else's phone call) is

of rare occurrence.

Applications Of LASERS5. Medicine₰ Used in medicine to improve precision work like

surgery.₰ Brain surgery is an example of precision surgery

that calls for the surgeon to reach the intended area precisely.

₰ Birthmarks, warts and discolouring of the skin can easily be removed with an unfocused laser.

₰ Operations are quick and heal quickly and, best of all, they are less painful

Everyday ApplicationsEveryday ApplicationsDVD/VCD PlayersLaser PrintersLaser Pointers and WritersLaser SightsSpeed Measurements using LaserLaser Distance MeterBar Code Readers in Retail StoresBy Hunters/Shooters instead of

ordinary telescope sights

Ω www.howstuffworks.comΩ www.nobleprize.orgΩ www.laserinternational.orgΩ www.laser.comΩ www.hyperphysics.phy-astr.gsu.eduΩ www.library.thinkquest.orgΩ www.xamplified.comΩ www.wikipedia.comΩ www.thebigger.comΩ www.britannica.com