Transcript laser - ArSCO منظمة المجتمع العلمي

‫)‪The Laser (II‬‬
‫‪•Types of Lasers‬‬
‫‪• Applications‬‬
‫‪• Safety‬‬
‫موزه بنت محمد الربان‬
‫أستاذ مشارك‬
‫فيزياء ذرية و ليزر‬
Types of Lasers
Most lasers consist of a column of active
material with a partly reflecting mirror
at one end and a fully reflecting mirror
at the other.
The active material can be solid (ruby
crystal), liquid or gas ( HeNe, CO2 etc.).
Types of Lasers
• Crystal lasers, also known as “solid state”
lasers.
• Liquid lasers
• Gas lasers
• Semiconductor lasers, sometimes called
diode lasers.
Types of Lasers 1
• Crystal lasers, also known as “solid state” lasers,
use a rod of crystal material positioned between
a pair of mirrors. Flash lamps are the most
common power source.
• The Nd:YAG laser emits infrared light at 1.064
nm.
The Ruby Laser
• Maiman’s first laser consisted of a rod of
synthetic ruby with reflective coatings at each
end that served as mirrors.
• A high power flash lamp pumped energy into the
rod.
• When fired, the device generated a pulsed red
laser beam that was powerful enough to pierce a
razor blade.
• Since then, hundreds of exotic crystal types have
been successfully used in lasers
The Ruby Laser
Invented in 1960 by Ted Maiman at
Hughes Research Labs, it was the first
laser.
Ruby is a three-level system, so you
have to hit it hard.
Types of Lasers 2
• Liquid lasers (Dye Lasers) use fluorescent dyes to
produce laser beams of many different colors. The dye
is flowed through a glass tube with laser mirrors
positioned on each end.
• Dye lasers can be tuned to produce almost any color of
light by changing the type and concentration of the
dye used, and by using special mirror arrangements
designed to allow only a specific wavelength of light to
circulate within the laser..
• Dye lasers find widespread use in scientific research
and in medicine where different types of living tissue
respond to different wavelengths of laser light.
Dyes cover the visible, near-IR, and
near-UV ranges.
Types of Lasers 3
Gas lasers are physically different than solid or
liquid lasers.
They consist of a laser tube made of quartz, glass,
ceramic, or in special cases, even metals.
At each end of the tube are the laser mirrors, and the
tube is also fitted with electrodes for applying a high
voltage to the gas.
Types of Lasers 3
Gas lasers
Gas laser tubes are electrically similar to common
fluorescent lights or neon signs. When high voltage is
applied, the gas in the tube ionizes and produces a
glowing light.
, the perfectly aligned mirrors gather and concentrate
a specific wavelength of light produced by the gas into
an intense laser beam.
Gas lasers produce extremely high quality laser beams,
many of which are of very high power, suitable for
cutting, welding and even some military applications.
The HeliumNeon Laser
Energetic electrons in a glow
discharge collide with and
excite He atoms, which then
collide with and transfer the
excitation to Ne atoms, an ideal
4-level system.
Carbon Dioxide Laser
The CO2 laser operates analogously. N2 is pumped, transferring the energy to
CO2.
Types of Lasers 4
Semiconductor lasers, sometimes
called diode lasers, are pn junctions.
Current is the pump source.
Today, the most widespread lasers are of the
semiconductor type. These lasers use semiconductor
materials similar to those found in transistors,
integrated circuit chips and light emitting diodes that
are commonplace in today’s electronic equipment.
Applications: laser printers or CD players.
Types of Lasers 4
• Semiconductor lasers are very small, often the size
of a grain of salt, so they are mounted in larger
packages for protection and efficient cooling. In most
cases they do not use separate mirrors as larger
lasers do. Rather, the ends of the semiconductor
material are cut so that the end faces are perfectly
parallel, and then coated to enhance reflectivity.
• Unlike gas lasers, they do not need dangerous high
voltages to operate.
..Some Laser Applications..
Now that we have
seen how lasers work
and some of the basic
types, lets look at
some interesting laser
applications… Lasers
have affected almost
every aspect of our
lives, and yet many of
us do not even realize
it.
much more intense, directionality,
coherency, high monochromatic , and ability to
reach extremely high powers are all properties
which allow for wide range of applications..
Applications..
http://www.repairfaq.org/sam/laserlia.htm
• Scientific
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Spectroscopy
Material processing
Photochemistry
Laser cooling
Nuclear fusion
Microscopy
• Industrial and
commercial
• Images
• Military
– Defensive
countermeasures
– Targeting
• Ranging
• Target designator
– Firearms
• Laser sight
• Eye-targeted lasers
• Medical
Universal Product Code, or UPC
Communications
Communications
Lasers and fiber optics will
soon replace most wires
A single strand of glass optical fiber can carry more than
half a million telephone conversations, or thousands of
computer connections and TV channels.
Thinner than a human hair, fiber optics promised unlimited
expansion for the future.
Fiber optics has been the driving force in the enormous growth
of the internet, arguably the single most influential social and
technological development of the 20th century… a development
that was made possible by the semiconductor laser.
“free space” optics
Some everyday applications of diode:
The common laser printer
Laser Printer
CD and DVD
Players and writers
shorter wavelengths can be focused to smaller spots
than longer wavelengths
A CD burner
The smaller the spot
size, the more pits can
be stored and read
from a CD or DVD
Laser measurement and quality control
Contractors use laser leveling equipment
Mapping laser scan data collected during construction onto 3D
design model of the building.
Surveying, mining and tunneling
applications
• Because lasers generate beams that are perfectly
straight, they can ensure a tunnel or mine shaft
remains straight during boring.
• The English Channel tunnel relied heavily on
laser alignment during its construction.
Because separate tunnels were
started from both the English and
French sides of the channel, it was
imperative that accurate
alignments be maintained
throughout the digging if they
were to meet in the middle of the
channel.
Laser welding and.. Cutting
Laser are an excellent choice for
fine cutting of a wide variety of
metals, ceramics and silicon
materials.
Near-IR wavelengths
are commonly used.
Material processing
Laser cutting, laser welding, laser brazing,
laser bending, laser engraving or marking,
laser cleaning, weapons etc.
lasers have found application in a very wide range of high precision
micromachining applications including sintering, ablation, fine pitch
soldering, trimming, direct metal deposition and many more.
Using mid-IR laser light
to shoot down missiles
Wavelength =
3.6 to 4.2 mm
The Tactical High Energy Laser uses a high-energy,
deuterium fluoride chemical laser to shoot down short
range unguided (ballistic flying) rockets.
Spectroscopy
Monochromaticity, makes the laser a very useful source for
spectroscopy.
Many spectroscopic techniques based on lasers can be used to
make extremely sensitive detectors of various molecules, able to
measure molecular concentrations in the parts-per-trillion (ppt)
level.
The high intensity of light that can be achieved in a small, well
collimated beam can also be used to induce a nonlinear optical
effect in a sample, which makes techniques such as Raman
spectroscopy possible.
Due to the high power densities achievable by lasers, beam-induced
atomic emission is possible: this technique is termed Laser induced
breakdown spectroscopy (LIBS).
Laser Technology Could Instantly
Identify Environment Hazards
New research indicates that a novel laser
technique may provide tremendous assistance
in strengthening homeland security. Laser
breakdown spectroscopy (LIBS) has the power
to instantly detect and identify a wide variety
of target materials, including chemical
substances in environment as well as
explosives and biological agents.
Laser and Photonics Solutions for
Environmental Sensing and
Spectroscopy
Laser Induced Breakdown Spectroscopy
In LIBS, a short laser pulse is focused on a
sample. Laser energy heats,
vaporizes, atomizes and ionizes
sample material generating small
area of plasma. Excited atoms and
ions in plasma emit secondary light
which is collected, spectrally resolved
by spectrophotometer and analyzed
by light detector. Each chemical
element has a unique “spectral
signature” which can be
discriminated from the obtained
spectra and therefore the multielemental composition of the sample
can be determined.
Photolithography
• Photolithography (also called optical
lithography) is a process used in microfabrication
to selectively remove parts of a thin film (or the
bulk of a substrate).
• It uses light to transfer a geometric pattern from
a photomask to a light-sensitive chemical
(photoresist, or simply "resist") on the substrate.
A series of chemical treatments then engraves
the exposure pattern into the material
underneath the photoresist.
shorter wavelengths can be focused to smaller spots than longer wavelengths.
Extreme Ultraviolet Sources for Lithography
Tomorrow’s Lithography will use EUV sources
 Year 2010 Wavelength λ=13 nm (EUV)
 Completely new optics for lithography
 Use mirrors instead of lenses
1.0
0.8
Mo-Si multilayer mirror
Reflectivity 68% at 13.5nm
0.6
0.4
0.2
0.0
12.5
13.0
13.5
14.0
Wavelength (nm)
14.5
Laser Produced Plasmas
We proposed mass-limited droplet technology many
years ago
Laser Produced Plasmas
Moving from Xe to Tin moves the UTA to 13.5 nm
Moreover, instead of just one ion species participating
in this UTA, many ions species emit at 13 – 14 nm
Gerry O’Sullivan, Physics Department, University College Dublin 3 rd EUVL Symposium, Miyazaki, 2nd-4th November 2004
In Medicine!!
Laser Light Show
Laser safety
As we have seen, lasers are
powerful and highly versatile
tools, but just like working
with any other tool, one must
keep safety foremost in mind.
Lasers can pose a number of
hazards depending on the
wavelength and power levels
involved.
Laser safety
• The semiconductor lasers used in
communications systems can
produce power levels that can
cause eye damage, and that
damage may not be immediately
noticed.
• Special protective glasses are
available for every laser
wavelength in use today, and
must be worn when working
around lasers.
• The dangers of high power lasers include eye
damage by beam energy reflected from
smooth surfaces as well as the possibility of
burns to clothing and skin.
• Eximer lasers that produce ultraviolet beams
can trigger skin cancers if the beam is
allowed to reach unprotected flesh.
• High power lasers can also start fires many
meters away from the laser if the beam path
is not completely enclosed.
Because of these potential hazards, all
countries now have stringent safety codes
that must be followed when working with
lasers.
http://www.safety.vanderbilt.edu/safety_links/laser.htm
So… Take care
Thank you