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LasersThe history of lasers and their every day

applications

LASER - Light amplification by stimulated emission of radiation

A Laser is a mechanism for emitting electromagnetic radiation.

A Laser usually emits light or visible light through a process called stimulated emission.

History Albert Einstein established the idea of the LASER and

MASER in 1917. In a paper entitled “On the Quantum Theory of Radiation,”

Einstein states that LASER and MASER technology is possible via a re-derivation of Max Planck’s law of radiation.

Planck’s law was based off of Einstein’s coefficient's for the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation.

Rudolf W. Ladenburg confirmed the existences of the phenomena of stimulated emission and negative absorption in 1928.

History R. C. Retherford and Willis E. Lamb discovered stimulated

emissions in the hydrogen spectra, and effected the first demonstration of stimulated emission in 1947.

in 1950, Alfred Kastler proposed a method known as optical pumping, which was experimentally confirmed by Kastler, Brossel, and Winter two years later.

Alfred Kastler would eventually receive the Nobel Prize for Physics in 1966 for his method of optical pumping.

The first functional laser was demonstrated at the Hughes Research Laboratories on May 16, 1960, by Theodore Maiman.

MASER “A MASER is a device that produces coherent

electromagnetic waves through amplification by stimulated emission

The Principles of the maser were described by Nikolay Basov and Alexander Prokhorov of the USSR in 1952, and officially published in October of 1954.

However, it was Charles H. Townes, J. P. Gordon, and H. J. Zeiger who built the first maser in 1953 at Columbia University.

Their device used stimulated emission in a stream of energized ammonia molecules to produce amplification of microwaves at a frequency of 24 gigahertz.

Later, Townes worked with Arthur L. Schawlow to describe the principle of the optical maser, or laser.

MASER The design of the maser is

based on Albert Einstein’s principle of stimulated emission.

When atoms are put into an excited state, they can amplify radiation at the proper frequency.

The feedback produced by putting an amplifying medium in a resonant cavity is what is known as coherent radiation.

How L.A.S.E.R.s Work The L stands for Light, a laser utilizes the forces of light

into a beam and directs this light for its power. The A stands for Amplification, this refers to magnifying

the light in order to make it more or less intense. The S stands for Stimulation, which is where the light

comes from.› Atoms are made of electrons, which when excited reach an elevated

state, much higher then their normal state.› The electrons in turn release their excess energy by giving off a

photon of light, and then return to their normal state.› When electrons of a particular substance are stimulated by light, get

charged up and in turn release photons of the same color.

How L.A.S.E.R.s Work The E stands for Emission, which is the release of light

energy. The R stands for Radiation, which is the entire process of

the stimulated emission of the photons. A LASER is finally created when the process above is

carried out in a controlled environment, using mirrors and lenses to collect the released photons.

Types of Lasers Solid State Lasers:

› This laser uses solid substance material, solid material that is used for lasing is generally stimulated by a flashlight or other type of light.

› You will get solid lasers that are in a continuous beam or a pulsed beam depending on whether the stimulation is continuous or intermittent.

› A few examples of solid lasing material are neodymium, ruby, and titanium sapphire.

Gas State Lasers:› In a Gas State Laser, the lasing material is in a gaseous state.› The two most common gases used to create gas lasers are

Helium and Helium-neon.› Gas Lasers are typically red in color.

Types of Lasers Excimer Lasers:

› This type of laser is made by employing gases to create the laser.

› Reactive gases are combined with inert gases, resulting in the release of a simulated molecule known as dimer.

› The dimer produces ultraviolet lasers upon lasing.› Because of this, the term Excimer comes from excited dimer.› Some examples of gases used are chlorine and fluorine

(Reactive), and argon, xenon, and krypton (Inert)

Semi-conductor Lasers:› These lasers are not solid state lasers, also known as diode

lasers.› Because a semi-conductor laser is not very powerful on its

own, it is usually used in conjunction with other lasers.

Special Properties of Lasers

Color of the Laser Light› The kind of light we all

see on a daily basis are forms of white light.

› Sunlight, light from a light bulb, etc. are all forms of white light, but not just white.

› Laser light is not the same however, it is only one solid color.

› This means that laser light is monochromatic and not polychromatic.

Invisible Laser Light› There are lasers such as

ultraviolet and infrared that give off light not visible to the naked eye.

› Invisible laser lights are used predominantly for protective security and alarm systems.

Special Properties of Lasers

Organizational Properties› The photons of light other

than laser light are unorganized and random.

› The photons of laser light, however, are very organized and consistent.

› The photons of both laser light and non laser light travel together at the same speed and in perfect alignment.

Focus of Laser Light› Because laser work on the

principle of stimulated emissions of photons, , the light itself becomes very focused and intense.

› The photons are released through their environment through very small openings, allowing the light to be focused and directed effectivly.

Lasers in the Medical World

Laser Eye Surgery› Lasers have been shown

to be effective for treating such things as far sightedness and cataracts.

› Because of the minute and direct laser beam used, it can easily and safely correct the damaged tissue while leaving the surrounding tissue in good shape.

 Laser Ulcer Removal› Lasers have proven very

useful when removing stomach ulcers.

› The laser beam is used to make a tiny incision in order to reach the ulcer, and because the ulcer burns the incision, the cut clots and seals immediately.

› Because of this, blood lose is minimal and healing time is also faster.

Lasers in the Medical World

Lasers and Electronics

Compact Disc Players› Compact discs are used to

store things such as music, and are played using a CD player.

› It is a laser that enables you to hear the music stored on the CD

› All CD’s have tiny lasers, which reads the digital codes and information and translates it into music.

Supermarket Scanners› Supermarkets scanners

are nothing more then laser scanning devices.

› These lasers read the information on the bar code.

› The information from the bar code is then processed through the computer data base.

Lasers and Electronics

Bibliography http://www.howstuffworks.com/laser.ht

m http://en.wikipedia.org/wiki/Laser http://

hyperphysics.phy-astr.gsu.edu/Hbase/optmod/lasapp.html

http://en.wikipedia.org/wiki/Maser http://

focus.aps.org/files/focus/v15/st4/pic-v15-st4-1.jpg

http://www.youtube.com/watch?v=48WkYbkhJO4