TopicSlide No.Introduction to Laser3 - 6Brief History of Laser7 - 9How Laser Works10-13Applications of Laser14Advantages of Laser15 - 19Disadvantages of Laser20 - 22Conclusion23

Many might think including me that Laser is just a word...But it is not so. It is a acronym.L - LightA - Amplified byS - StimulatedE - Emission of R - RadiationIntroduction to laser

Now let us see some 3 sources of light

From the above Table we can say that :(a) The Sun has high light power but has less density or intensity.(b) But Laser has very high intensity but less power. This makes laser a powerful device.

Laser has some of its own properties. Some are :(a) It is nearly 100% monochromic i.e. it travels for long distance in a uniform frequency & wavelength,(b) It is nearly 100% perfectly directional i.e. it travel only in a particular direction without diverging. (c) It is 100% coherent i.e. the distance between each wave is equal at a given point on the line which is perpendicular to the base of laser source.

DirectionalMonochromic

Brief History of laser

YearNameAchievement1900Max PlankSaid that light is a form of electromagnetic radiation1916Albert EinsteinTheory of light emmision1951Charles H TownesJoseph WeberJames P. GordanThe inventor of MASER (MicrowaveAmplification of Stimulated Emission of Radiation)1957Gordon GouldFirst document defining a LASER1959John D. MyersFirst stroboscopic X-Ray system.16/05/1960Theodore MaimanInvented first working LASER based on Ruby.1960Peter P SorokinMirek StevensonFirst Uranium LASER

YearNameAchievement1960Ali Javan,William BennettDonald HerriotFirst helium-neon LASER1961Elias SnitzerFirst glass LASER1961Leo F. Johnson,K. NassauFirst neodymium crystal LASER1962Robert HallNick HolonyakInvention of semi-conductor LASER1962Alan WhiteDane RigdenFirst helium neon (HeNe) visible CW LASER1964William BridgesInvention of Argon Ion LASER1965John D. MyersFirst dual frequency LASER1965George PimentelJ V V KasperFirst chemical LASER1965John D. MyersFirst frequency-doubled LASER rangefinder

YearNameAchievement1966John D. MyersFirst plane position indicating LASER radar1967Bernard SofferB. B. McFarlandFirst wavelength tunable dye LASER1969G M DelcoFirst industrial installation of three LASERSfor automobile application1980Geoffrey PertsGroupFirst report of X-ray using LASER action1984Dennis MatthewsGroupDemonstration of X-ray using laser1985John D. MyersFirst commercial LASER eye surgery1996Wolfgang KeterleFirst pulsed atom LASER at MIT2006John BowersFirst silicon LASER2010First 10 Petawatt LASER

How Laser Works

Animation

Spontaneous EmissionExcited atoms normally emit light spontaneouslyPhotons are uncorrelated and independentIncoherent light

Stimulated EmissionExcited atoms can be stimulated into duplicating passing lightPhotons are correlated and identicalCoherent light

Laser AmplificationStimulated emission can amplify lightLaser medium contains excited atom-like systemsPhotons must have appropriate wavelength, polarization, and orientation to be duplicatedDuplication is perfect; photons are clones

Applications of Laser

Medical UsesLaser CoolingCutting and WeldingNuclear FissionSurveying and RangingPhotochemistryIn Garment IndustryLunar Laser RangingIn CommunicationMicroscopyHeat TreatmentTargetingBarcode ScannersArms and WeaponsMetrologySpectroscopy

Military

Advantages of LaserLaser Surgery:

Results are good in cosmetic senseMultiple lesions could be treated with laser surgeryBirthmarks and pigmented lesions could also be treated with laser which was considered as untreatable in pastLess complication after treatment.

Laser Beam Cutting

(a) Due to rapid rate of operation, the (heat) distortion to the base metal is minimum. (b) The narrowness and accuracy of the cut together with relatively shallow HAZ with negligible surface cracking are major advantages of this process. (c) Even most complicated profiles can be cut. (d) Very hard material like silicon carbide, friable material like glass, sticky material like confectionery etc., can be cut by laser. (e) Laser is a faster process than sawing or nibbling and is very efficient.

Laser Beam Cutting

Operation on eye using Laser:

(a) Being able to see well without having to wear glasses or contacts (b) Improved appearance (c) Greater choices in sunglasses styles (d) Not having to worry about losing or breaking glasses (e) No worries about having to buy expensive cleaning solutions for contacts or new contacts every few months

Gas Detection with a Laser.

(a) Because of the very narrow 0.3 nm line width of the laser emission, there is no interference from other gases.(b) Response times are in the order 1 second. This allow for fine resolution/control when making process measurements.(c) The intense laser light concentrated at the absorption wavelength enables path lengths up to 1 km to be measured.(d) An average measurement is taken over the total path so that a narrow plume of gas has less chance of escaping detection.(e) The range of measurement can be up to 4 orders of magnitude, enabling concentrations of 0.1 ppm to 1000 ppm to be measured.(f) Because of the internal reference cell, the system is self calibrating.(g) There is no poisoning or degradation of the instrument with long term exposure to a gas.(h) Can easily be conformed to be Intrinsically Safe.(i) Low maintenance and low operating costs.(j) Reliable technology.

Disadvantages of Laser

Laser Surgery:

(a) Laser surgery is costly as equipment are very costly.(b) Repeated laser treatment could be required.(c) Any type of local infection could complicate laser treatment.(d) Scarring or altered skin texture is also a possibility.

Operation on eye using Laser:

(a) Expensive. The greater the correction, the higher the cost (b) Not everybody can benefit from it. Those with thin corneas or large pupils are considered to be poor candidates for it (c) Bad night vision. Many people complain about the halo effect or seeing star bursts around lights (d) Dry eyes. It can be permanent in some people (e) Overcorrection or undercorrection (f) Results often don't last and for older people, they likely will need glasses again (g) It permanently weakens the cornea and increases its risk for rupture

Laser Beam Cutting

(a)The limit on thickness of section (6 mm in plain carbon steel; for other metals it is still lesser) and the fact that workpiece must be moved relative to the rather cumbersome equipment restrict the use of gas-jet laser cutting.

Gas Detection with a Laser.

(a) Only one gas can be measured with each instrument. (b) When heavy dust, steam or fog blocks the laser beam, the system will not be able to take measurements. This is also the case when a person or vehicle blocks the path.

ConclusionFrom the above slides we understand :Invention of LaserHow laser works Its applicationIts Advantages & Disadvantages

Last but not the least, I want to say that Lasers are nowadays used in many places as it time saving & very efficient even though it is costly. Laser has disadvantages but has many advantages due to which it has become popular.

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