AA Amplification by
EE Emission of
A laser is a device thatA laser is a device that
transforms light of varioustransforms light of various
frequencies into a chromaticfrequencies into a chromatic
radiation in the visible, infrared,radiation in the visible, infrared,
and ultraviolet regions with alland ultraviolet regions with all
the waves in phase capable ofthe waves in phase capable of
mobilizing immense heat andmobilizing immense heat and
power when focused at closepower when focused at close
WHAT IS A LASER ?
CHARACTERISTICS OF LASER
1 COHERENCE :
The wave trains which are identical in phase and
direction are called coherent waves.
2 HigH iNtENsity :
Due to the coherent nature of laser, it has the ability
to focus over a small area of 10
3 HigH diRECtiONality :
The angular spread of a laser beam 1mm/meter.
4 HigH mONOCHROmatiCity :
The light from a normal monochromaticity source
spread over a range of wavelength of the order
100nm.but, the spread is of the order of 1nm for
stimulatEd aNd spONtaNEOus
It is not a random
The photon get
t is a controllable
It is random process.
The photon do not get
multiplied through chain
It is a not controllable
Nd yag rod and krypton flash lamp are
enclosed inside in ellipsoidal reflector.
In order to make the entire flash
radiation to focus on the laser rod.
The nd yag rod is placed t one focal axis
and the flash lamp at the other focal
axis of the ellipsoidal reflector.
Energy level Diagram
The flash lamp switched on.
The optical pumping excites the ions from the
ground energy state E0 to the higher energy
level E3 and E4 by absorbing radiation .80µm
The energy level E4 to E2 is the non radiative
The E2 state is meta stable state.
Any of the spontaneously emitted photon will
make the excited ion to undergo a transition
between E2 E1 state.
The transitions E2 E1 yields an intense and
coherent laser beam of wavelength 1.064µm.
These laser give beam continuously.
The ions then make a transition between E1 E0.
The flash lamp is used to excite the ions, while the rest
heats up the crystal.
Thus, the system can be cooled by either air or water
APPLICATION OF LASER
A) IN INdUSTRy :
1) For welding and melting.
2) For cutting and drilling holes.
3) To test the quality of the material.
B) IN mEdICINE :
1) Used for treatment of detached retinas.
2) Used in performing micro and bloodless surgery
C) Military appliCations :
1) The laser beam can serve as war weapon,
i.e. A power full laser beam can be used to destroy in
few second, the big size object like aeroplanes, missiles etc.
D) sCienCe anD engineering appliCation :
1)Fiber optic communication.
2)It is used to holography.
3)Communication between planets is possible with
4) It is used to accelerate some chemical reaction.
5) It is used to drill minute holes in cell walls without
damaging the cell itself.
Continuous Output (CW) Pulsed Output (P)
watt (W) - Unit of power or radiant flux (1 watt = 1 joule per second).
Joule (J) - A unit of energy
Energy (Q) The capacity for doing work. Energy content is commonly used to characterize the output
from pulsed lasers and is generally expressed in Joules (J).
Irradiance (E) - Power per unit area, expressed in watts per square centimeter.