This document provides information about lasers, including their history, principles, applications, characteristics, types, and components. It discusses how lasers were invented in 1958 and work using stimulated emission. Key applications mentioned include uses in CDs/DVDs, barcodes, welding, medicine, and more. The principles of how lasers achieve population inversion and stimulated emission are described. Different types of lasers like gas, solid, liquid, and semiconductor lasers are outlined. The basic elements that make up any laser system including the active medium, pumping energy, optical amplifier, and mirrors are also summarized.
3. HISTORY
• Invented in 1958 by Charles Townes (N.P.1964) and Arthur
Schawlow.
• Based on Einstein’s idea of the particle wave duality of light.
• Originally called MASER (M=microwave).
INTRODUCTION
• LASER = Light Amplification by Stimulated Emission of
Radiation.
• Laser is an electric device that produced light (EM
radiation), through a process of optical amplification.
• When they return to lower energy levels by stimulated
emission ,they emit energy.
4. APPLICATION
• These application are used in CD, DVD, ROM.
• They are also used in barcode scanner.
• Used as an integral part of nuclear fusion.
• It is also used for alignment welding, swolding,
drilling, and surface treatment in the medical
equipment and cosmetic treatment also.
5. PRINCIPLE
• When an atom is in excited state, a light photon of
the same frequency which is to be emitted by the
atom falls upon it.
• Then the atom is immediately comes down to the
normal state or ground state & stimulate the incident
ray by emitting the photon of exactly the same
frequency.
• This type of emission,
is called stimulated emission.
6. CHARACTERSTICS
• Laser light is highly Coherent
• Laser light is highly Monochromaticity
• Laser light is having Directionality
• These rays go to long distance without absorption.
• They are not absorb in water
• Laser beam can vaporized even the hardest material
• The colour of laser light can be changed
• Brightness
7. USES
In the technique field-
• The laser beam is used for cutting steel, sheets, melting and
drilling of hard materials.
• It can create hole in diamond.
In the medical field-
• The laser beam is used in delicate surgery as corneal grafting
with laser beam, and it’s completed in much shorter time.
• It is also used for laser treatment of retina & iris.
• It is also used in treatment of kidney stone, cancer, tumours
and depositing ,cutting the blood cells in the brain operation.
8. During war times-
• Laser are used to detect and destroyed the enemy messiles.
• Used in laser pistols.
• In space laser has been use to controlled rockets, satellites and
unidirectional radio communication.
In science and research-
• It can be used to determine temperature of plasma and density of the
electrons laser torch is used to see objects as long distance.
Laser is used for 3D photography or holography.
There are used in measuring long distance ,the distance b/w earth and
moon has been measured by laser beam.
It is useful to detecting nuclear exposure and earthquakes in vaporizing
solid fuels of rocket.
Used to study od the surface of the distant planets and satellites.
9. TYPES
They are many types of laser-
• Gas laser
• Solid laser
• Liquid laser
• Semi conductor laser
• Dyes laser
• Metal vapour laser
• Excimer laser
• YAG laser
• Argon laser
10. Gas laser-
• These laser contains a mixture of He & Ne.
• This mixture is packed up into a glass tube.
• This packed mixture acts as an active medium.
• It is also k/a coherent light wave.
Solid laser-
• In this a ruby like crystal is used which acts as an active
medium.
• It is basically cylindrical in shape.
• The crystal is surrounded by a xenon flash pump.
• The flash pump is helical in shape.
11. Liquid laser-
• In this laser organic dyes are used as active medium inside the glass
tube.
Semi conductor laser-
• Sometimes semi conductor is c/d diode laser are not solid state laser.
• E.g.- the writing source in some laser printers or CD players, in these
laser junction diode are used.
• There is p-n junction diode is also used.
Dyes laser-
• This type of laser is used in laser medicine, spectroscopy, birthmark
removal, isotopes separation and research field.
12. Metal vapour laser-
• This type of metal laser are present in which are used in printing,
scientific, research, ametour laser, construction, dermatological used
,high speed photography etc.
• It include gold vapour laser, Cu laser ,Ne-Cu metal vapour laser ,He-
Cd laser ,He-Se laser ,He-Ag metal vapour laser.
Excimer laser-
• The excimer laser invented by Nikoloi Basove, 1970.
• An excimer laser is a form of UV laser which is commonly used in the
production of microelectronic division, eye surgery and
micromachining.
• It is also c/d Exiplox laser
13. Wavelength determine -
• The wavelength determination of excimer laser d/o the molecule and is
usually of in the wavelength.
Used of excimer laser-
• In medical field
• In scientific research
EXCIMER WAVELENGTH
Ar2 126 nm
Kr2 146 nm
Xe2 1724 nm
14. YAG laser-
• YAG =yttrium aluminium-garnet
• Laser operation of YAG was first demonstrated by J.E.Geusic et
al.,1964.
• YAG is a crystal i.e used a lasing medium for solid state laser.
• It is the neodymium ion which provides the lasing activity in the
crystal,in the same fashion as red chromium ion in ruby laser.
Argon laser-
• Ar laser is a laser system that uses noble gas as the active medium.
• Ar gas laser are used in many application such as forensic
medicine,general surgery, ophthalmic surgery and holography.
15. ELEMENTS OF LASER
All laser used in ophthalmology consist of the following basic
elements-
• An active medium
• Energy input(pumping)
• Optical amplifier
• Release of laser
• Partially reflecting mirror
• Fully reflecting mirror
16. An active medium-
• An active medium in laser provides an atomic or molecular
environment.
• Due to presence of this medium ,a large number of atoms in the active
medium( solid ,liquid or gas ) get energized above their original
ground state on stimulation by a photon of light followed by stimulated
emission.
Energy input(pumping)-
• Lasers systems also requires a source of energy to keep majority of
atoms in an energy state higher than their original ground state in the
active medium.
• This state is termed as population inversion.
17. Optical amplifier-
• Third requirement for a laser system is optical amplification where is
light amplified by an optical feedback system.
• Release of laser-
• Laser system also contains mechanism to release laser beam from the
laser cavity.
• Releasing of laser is achieved by making one mirror fully reflective
and another mirror partially reflective.
• Those amplified stimulated light waves which strike the partially
reflecting mirror gets emitted from the laser cavity as laser beam.
