- 1. TOPIC :- LASER NAME :- SIDDHI SHRIVAS DIVISON :- COMPUTER C
ENROLLMENT NUMBER :- 130770107163 FACULTY NAME :-Mr. VIPUL
PATEL
2. ASER MPLIFICATION BY TIMULATED MISSION OF ADITION The Word
LASER Is An Acronym For : 3. INTRODUCTION LASER in an acronym for
Light Amplification By Stimulated Emission of Radiation. The first
laser, namely, Ruby Laser was demonstrated by T.H.Maiman , in the
year 1960. The discovery of laser made an enormous impact in the
scientific world and showed that the function of optics was very
much alive. 4. A Laser is a mechanism for emitting electromagnetic
radiation. A Laser usually emits light or visible light through a
process called stimulated emission. A laser is a device that can
produce a very narrow intense beam of monochromatic coherent light.
The emitted beam is nearly perfect plane wave. In short, A laser is
a device that emits light through a process of optical
amplification based on the stimulated emission of electromagnetic
radiation 5. CHARACTERISTICS OF LASER LIGHT o Monochromatic o
Directional o Coherent o High intensity 6. The light emitted from a
laser is monochromatic , that is, it is of one color/wavelength. In
contrast, ordinary white light is a combination of many colors (or
wavelengths) of light. Lasers emit light that is highly directional
, that is, laser light is emitted as a relatively narrow beam in a
specific direction. Ordinary light, such as from a light bulb, is
emitted in many directions away from the source. The light from a
laser is said to be coherent, which means that the wavelengths of
the laser light are in phase in space and time. Ordinary light can
be a mixture of many wavelengths. These three properties of laser
light are what can make it more hazardous than ordinary light.
Laser light can deposit a lot of energy within a small area. 7.
EINSTEIN'S THEORY EINSTEIN EXPLAINED THE ACTION OF LASER BEAM BASED
ON QUANTUM THEORY OF LIGHT . Production of laser light is a
particular consequence of interaction of radiation with matter. 8.
THREE process that occur when light Interacts with MATTER are: o
Induced Absorption. o Spontaneous Emission. o Stimulated emission.
9. 1. INDUCED ABSORPTION If a photon of energy hv is incident on
the atom in the lower state, the incident photon and gets excited
to the higher energy state E2. this process is called induced
absorption. Normally, the higher energy state is an unstable state
so the atoms will make a transition back to the lower energy state
with the emission of a photon. 10. photon Before absorption After
absorption E2 E1 E2 E1 INDUCED ABSORPTION 11. THE RATE OF
ABSORPTION R12 IS PROPORTIONAL TO THE POPULATION OF THE LOWER
ENERGY LEVEL N1 AND TO THE DENSITY OF INCIDENT RADIATION . HENCE,
R12 N1 R12 =B12N1 WHERE B12 I STHE PROPOTINALITY CONSTANT KNOWN AS
THE PROBABILITY OF ABSORPTION OF RADIATION PER UNIT TIME. 12. 2.
SPONTANEOUS EMISSION In spontaneous emission the atoms or molecules
in the higher energy state E2 eventually return to the ground state
by emitting their excess energy spontaneously. The process is
independent of external radiation . The rate of spontaneous
emission is directly proportional to the population of the energy
level E2. 13. After emission Atom in ground stateAtom in excited
state Before emission During E2 E1 hv=E2-E1 SPONTANEOUS EMISSION
14. 3. STIMULATED EMISSION When electron transits from higher level
to lower level in presence of external energy is known as
stimulated emission. In stimulated emission a photon having energy
E equal to the difference in energy between the two levels E2 and
E1 , stimulate an atom in the higher state to make a transition to
the lower state with the creation of second photon. 15. Excited
state Before emission E1 E2 After emissionie, STIMULATED EMISSION
16. According to Einstein's, under certain condition it is possible
to force an excited atom emit a photon by another photon and the
incident light wave must be in same phase .hence we get an enhance
beam of coherent light 17. DIFFERENCE STIMULATED EMISSION
SPONTANEOUS EMISSION Emission of a light photon takes place through
an inducement i.e. by an external photon. Emission of a light
photon takes place immediately without any inducement. It is not a
random process. It is a random process. The photons get multiplied
through chain reaction The photons do not get multiplied through
chain reaction. It is a controllable process It is an
uncontrollable process More intense less intense Monochromatic
radiation Polychromatic radiation 18. BASIC CONCEPTS IN LASER :
Population inversion : is a state of achieving more number of atoms
in the excited state compared to ground state Pumping Spontaneous
emission or/and collisions Pumping 19. Pumping : is the mechanism
of exciting atoms from the lower energy state to a higher energy
state by supplying energy from an external source Active medium: A
medium in which population inversion is achieved for laser action
is called active medium. The medium can be solid, liquid, gas and
plasma. Optical resonators :A pair of concave mirrors placed on
either side of the discharge tube, one completely polished and the
other partially polished. 20. Therefore in a laser. Three key
elements in a laser Pumping process prepares amplifying medium in
suitable state Optical power increases on each pass through
amplifying medium If gain exceeds loss, device will oscillate,
generating a coherentoutput 21. Nd: YAG Laser (Neodymium Yttrium
Aluminium Garnet Laser) 22. Nd (Neodymium) YAG (Yttrium Aluminium
Garnet) LASER Principle Characteristics Doped Insulator laser
refers to yttrium aluminium garnet doped with neodymium. The Nd ion
has many energy levels and due to optical pumping these ions are
raised to excited levels. During the transition from the metastable
state to E1, the laser beam of wavelength 1.064m is emitted 23.
DIAGRAM : Power Supply Capacitor Resistor Laser Rod Flash Tube M1
100% reflector mirror M2 partial reflector mirror 24. CONSTRUCTION
: Essential parts of laser:- Yttrium Aluminium Garnet in which 1.5%
of neodymium ions are doped as impurities. Nd3+ is the lasing ion.
Two end mirrors M1 (total reflector) & M2 (output coupler)
Excitation is achieved by krypton or xenon arc lamps Nd : YAG laser
rod has a length of about 5-10 cm with a diameter 6- 9mm. It is
kept at one foci of an elliptical glass tube. Krypton arc lamp ,
the optical source is placed at the other foci of the glass tube.
It is provided with necessary power supply arrangement. Mirrors M1
(total reflector) & M2(output coupler) act as a resonant cavity
to produce stimulated and amplification process. 25. ENERGY LEVEL
DIAGRAM Simplified energy level diagram for the Nd-ion in YAG
showing the principal laser transitions Non radiative decay Laser
1.064m Non radiative decay E3 E2 E0 E1 E4 Nd E1, E2, E3 Energy
levels of Nd E4 Meta Stable State E0 ground State Energy Level 26.
APPLICATION OF LASER: Industry Weapons Drilling And Cutting In
Medical World Communication Computer Chemistry Photography 27.
INDUSTRY 28. WEAPONS 29. Drilling And Cutting: 30. Lasers in the
Medical World 31. COMMUNICATION 32. COMPUTER 33. CHEMISTRY 34.
PHOTOGRAPHY 35. CONCLUSION Lasers are device which amplify light
and produce beams of light which are very intense, directional and
Pure in colour. Laser action is preceded by three processes namely
absorption, spontaneous emission and stimulated emission. They can
solid state ,gas, semiconductor or liquid. Laser can be used for
many applications ,helped people develop in many things in our
daily life. 36. THANK YOU
