The document discusses lasers, including their characteristics and operation. It describes how lasers work via stimulated emission and population inversion. Nd:YAG lasers are discussed as a common solid-state laser type. Applications of lasers mentioned include medicine, manufacturing, communications, and more.
This belongs to Physical Chemistry portion and it contains most of
things about laser working and principles.
By Aaryan Tyagi's Group
M.Sc. Applied Chemistry (1 Sem)
Amity University, Noida
This belongs to Physical Chemistry portion and it contains most of
things about laser working and principles.
By Aaryan Tyagi's Group
M.Sc. Applied Chemistry (1 Sem)
Amity University, Noida
(A) By active media
Solid state laser - crystal, or glass, doped with impurities, e.g. ruby laser, Ti:sapphire laser, semiconductor laser.
Gas laser - e.g. He-Ne laser, Ar+ laser, CO2 laser, N2 laser, HCN laser.
Dye laser - active medium: dye molecules in liquid solvent (sometimes in solids also).
(B) By mode of operation
CW
Pulsed
(C) By pumping and laser levels
3-level laser
4-level laser
Laser is very important technological device these days.There is a use of laser in almost every field of science and technology. It also gives it's application in medicines also.
This presentation shows how it works and what is the mechanism behind this laser phenomenon. Here it is explained from atom theory to application.
Very good explanation with photographs.
A ruby laser is a solid-state laser that uses the synthetic ruby crystal as its laser medium. Ruby laser is the first successful laser developed by Maiman in 1960.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation
(A) By active media
Solid state laser - crystal, or glass, doped with impurities, e.g. ruby laser, Ti:sapphire laser, semiconductor laser.
Gas laser - e.g. He-Ne laser, Ar+ laser, CO2 laser, N2 laser, HCN laser.
Dye laser - active medium: dye molecules in liquid solvent (sometimes in solids also).
(B) By mode of operation
CW
Pulsed
(C) By pumping and laser levels
3-level laser
4-level laser
Laser is very important technological device these days.There is a use of laser in almost every field of science and technology. It also gives it's application in medicines also.
This presentation shows how it works and what is the mechanism behind this laser phenomenon. Here it is explained from atom theory to application.
Very good explanation with photographs.
A ruby laser is a solid-state laser that uses the synthetic ruby crystal as its laser medium. Ruby laser is the first successful laser developed by Maiman in 1960.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation
An optical fiber (or optical fibre) is a flexible, transparent fiber made of high quality extruded glass (silica) or plastic, slightly thicker than a human hair. It can function as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber.
A laser is a device that generates light by a process called STIMULATED EMISSION.
The acronym LASER stands for Light Amplification by Stimulated Emission of Radiation
Semiconducting lasers are multilayer semiconductor devices that generates a coherent beam of monochromatic light by laser action. A coherent beam resulted which all of the photons are in phase.
Contents
Definition of a laser
Emission and absorption of radiation
Population Inversion
Optical Feedback
Fundamentals of laser operation
Laser Hazards
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation"
Lasers have many important applications. They are used in common consumer devices such as DVD players, laser printers, and barcode scanners. They are used in medicine for laser surgery and various skin treatments, and in industry for cutting and welding materials. They are used in military and law enforcement devices for marking targets and measuring range and speed. Laser lighting displays use laser light as an entertainment medium. Lasers also have many important applications in scientific research
Laser is a light source but it different from ordinary light sources due their peculiar characteristics. In general ordinary light produces due to spontaneous emission of radiation but in the case of lasers its due to the stimulated emission of radiation.
Presentation on laser for Physics B.Sc. students by Dr. P D Shirbhate assistant Professor, Department of Physics G S Gawande college, Umarkhed Dist Yavatmal.
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Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
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3. LASER is an acronym for Light Amplification by Stimulated
Emission of Radiation.
Laser are optical phenomena which find major application in
various fields such as medicine, engineering, fiber optic
communication, industries etc.
Einstein proposed idea to amplify light and microwaves by
utilizing the energy which is released by atoms or molecules
during energy level transitions.
Outline an application of the use of a laser; medical
applications, communications, bar-code scanners, laser disks,
surveying, welding and machining metals, drilling tiny holes
in metals, production of CDs, reading and writing CDs,
DVDs, etc.
4.
5. Mono chromatic light has a very narrow range of
frequencies (i.e. it is only made of light of one colour)
6. The following characteristics, distinguishes a laser
beam from an ordinary light.
Highly Monochromaticity.
Highly Directionality.
Coherence.
Intensity.
7. Mono means single and chrome means colour, there
fore mono chromaticity is a source with single colour.
It is important to note that energy radiation for all
atoms is corresponds to their respective energy level.
So that frequency of laser light is constant (E = hv).
LASER radiates light having single frequency
wavelengths known as “Monochromaticity”
This characteristic is very useful in medical treatment
because the biological effect is strongly related to the
wavelength of light and also used as source in many
laboratory experiments
8. Laser is almost perfectly parallel.
This means that it has good directionality.
For the same power, normal light can travel very small
distance before it is diverted but laser could travel very
large distance almost without diversion
∆θ=λ/D
θ =angle of divergence.
D =diameter of source aperture.
Used as ranging device and also useful
to study plantry distance.
9. (3) High Intensity :
Due to the coherent nature of laser, it has the ability
to focus over a small area of 10-6 cm2, i.e.,
extremely high concentration of its over a small area.
(4) Coherence :
The wave trains which are identical in phase and
direction are called coherent waves.
Since all the constituent photons of laser beam
possess the same energy, momentum and propagate
in same direction, the laser beam is said to be highly
coherent.
10. In 1916, according to Einstein, the interaction of
radiation with matter could be explained in terms of
three basic processes:
1) Absorption
2) Spontaneous Emission,
3) Stimulated Emission.
The three processes are illustrated and discussed in
the following:
11.
12. Let the atom be initially in the lower state E1. If a
photon of hv is incident on the atom in the lower state,
the atom absorbs the incident photon and gets excited
to the higher energy state E2. This process is called
induced absorption as shown fig. 1.
BEFORE AFTER
13. It is a process in which there is an emission of a photon
whenever an atom transits from a higher energy state to a
lower energy state without the aid of any external agency.
For this process to take place, the atom has to be in the excited
state. Since, the higher energy level is an unstable one, the
excited atom in the higher energy level E2 spontaneously
returns to the lower energy level E1 with the emission of a
photon of energy h =E2-E1 as shown in fig.
BEFORE AFTER
14. Quite by contrast “stimulated emission” requires the presence of external
radiation when an incident photon of energy h =E2-E1 passes by an atom
in an excited state E2, it stimulates the atom to drop or decay to the lower
state E1.
In this process, the atom releases a photon of the same energy, direction,
phase and polarization as that of the photon passing by, the net effect is two
identical photons (2h) in the place of one, or an increase in the intensity of
the incident beam. It is precisely this proc esses of stimulated emission
that makes possible the amplification of light in lasers.
15. Population Inversion :
It is a state of achieving more number of atoms in the excited
state compared to the ground state.
It can be achieved by a process called pumping.
Pumping :
It is the mechanism of exciting atoms from the lower
energy state to a higher energy state by supplying energy from
an external source. The most commonly used pumping
mechanism are described below.
1) Optical Pumping
2) Electrical Pumping
3) Direct Conversion
Lasing :
The process which leads to emission of stimulated photons
after establishing the population inversion is referred to as
lasing.
16. Life Time
The limited time for which a particle or an atom remains in
the excited is known as life time.
It is about a nano second.
Metastable
It state are the energy levels in an atomic system where the
life time of atoms is very large.
Achieve Medium
Based on the achieve medium & method of pumping, the
lasers are classified into
1. Solid State Lasers
2. Liquid Lasers
3. Gaseous Laser
4. Dye Lasers
5. Semiconductor Lasers
17. Active Medium
This is a four-level solid state laser system. Yttrium
Aluminum Garnet, commonly known as YAG, doped with
neodymium ions Nd+3 is the active medium.
Resonator Cavity
The end faces of the Nd: YAG rod are ground polished
and silvered to act the optical resonator mirrors, or the
optical cavity can be formed by using two reflecting mirrors
M1 & M2.
Optical Pumping
A xenon flash lamp or a krypton flash lamp as a
pumping source.
18.
19. These lasers are used in widely for cutting, drilling,
welding and surface hardening of the industrial
products.
It is used in long communication.
It is used in the study of inertial confinement fusion.
Medical field for Opthalmic (Eye) surgery and
cosmetic surgery.
Communication and remote sensing field.