INTRODUCTION TO LASERS
TECHNOLOGY EDUCATION
SCARSDALE MIDDLE SCHOOL
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Many of the pictures for
this “LASER” presentation came
from www.howstuffworks.com.
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LASER
• Originally LASER was an acronym for Light
Amplification by the Stimulated Emission of
Radiation.
• Now laser is a word used to identify this type
of equipment or the light it produces.
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The Atom
Different electron orbits represent different energy levels.
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The Electron
Applying energy to an electron causes it to jump
to a higher orbit.
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The Photon
When the electron drops back to its original orbit it
releases a particle called a photon. Light is made up
of photons.
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Wavelength of Light
Light moves in waves that are similar
to ripples in water.
Light is an example of electromagnetic radiation: It doesn’t
require a medium to pass through
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Wavelength of Light
1 CYCLE
Wavelength (λ): The distance the wave travels
in one cycle.
Frequency (f): The number of times a cycle
repeats in one second (Hertz,
formerley cycles/second).
λ=
c
f
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Wavelength of Light
HERTZ
λ
~ 400 nanometers
H
I
G
H
E
R
ENERGY
L
E
S
S
F
E
R
N
E
E
Q
R
U
G
E
Y
N
C
~ 700 nanometers
Y
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1 NANOMETER IS ONE BILLIONTH OF A METER
A human hair is about 80,000
nanometers in diameter.
That’s about 115 times the
wavelength (λ) of red light.
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Light Bulb
Light is not focused
Light is made up of many colors (wavelengths)
Light is not coherent
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White Light
Light From A
Light Bulb
•All colors
(wavelengths).
•More longer
wavelengths.
•Light is not
coherent.
•Light is not
focused.
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Laser Light
Light is very focused
Light is made up of one color (wavelength)
Light is coherent
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Laser Light
Light From A
Laser
•One color
(wavelength).
•Light is
coherent.
•Light is focused.
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Theodore Maiman
First Ruby Laser
1960
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How a Laser Works
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Ruby Laser
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Types of Lasers
Based on the Material Used in the Laser
Classes of Lasers
Based on the Biological Damage the Laser
Can Cause
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Typical Lasers and Their Emission Wavelengths
Laser Type
Wavelength (nm)
•Argon fluoride (UV)
•Krypton fluoride (UV)
•Nitrogen (UV)
•Argon (blue)
•Argon (green)
•Helium neon (green)
•Helium neon (red)
•Rhodamine 6G dye (tunable)
•Ruby (CrAlO3) (red)
•Nd:Yag (NIR)
•Carbon dioxide (FIR)
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248
337
488
514
543
633
570 - 650
694
1064
10600
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Optical Damage Threshold Test
NASA Research Center
The Optical Damage Threshold test station at NASA Langley
Research Center has three lasers: a high-energy pulsed ND:Yag laser,
a Ti:sapphire laser and an alignment HeNe laser.
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Classes of Lasers
Based on the Biological Damage the Laser Can Cause
Class I: Lasers that don’t produce any harmful
radiation.
Class II: Lasers that are harmful if viewed for
long periods of time. (The assumption is
that
people wouldn’t let this happen.)
Class III: Lasers that are dangerous for short
exposure. (Many laser pointers are class
III lasers!)
Class IV: Lasers that can blind or burn after a very
brief exposure. These can only be used
under
very controlled conditions.
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LASER WEAPONS
“Do you expect me to talk Goldfinger?”
“No Mr. Bond, I expect you to die.”
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Laser Gun Sights
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Multiple Integrated Laser Engagement System
MILES (2000)
“Laser Tag” for Soldiers
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Laser Targeting System
Aircraft Mounted
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Laser Guided Bomb
(“Smart” Bomb)
Control surfaces
Guidance system
Optical sensor
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Laser Targeting
2. Laser guided
weapon tracks
laser spot on
target.
1. Laser targeting
system “paints”
target.
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Laser Targeting System
Ground Based
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Laser Targeting Countermeasures
AN/VVR-1 Laser Warning Receiver System
System
detects
the targeting
laser.
Countermeasures
include smoke,
brighter laser
beam,
maneuvering,
etc.
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Laser Guided Missile
Hellfire laser guided missiles mounted on a
US Army Apache helicopter gunship.
Newer variation (Hellfire II) replaces laser guidance
with radar guidance to penetrate smoke and cloud cover.
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ABL
Airborne Laser
Antimissile Weapon
United States Air Force
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ABL
Nose Turret
CO2 Targeting Laser
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LASERS IN MANUFACTURING
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Punch Press
Typical Stamped Parts
Punch Press Problems
•Dangerous to operate.
•Required long runs
to be profitable.
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Laser Cutter
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Computer Control
of Laser Cutter Equipment
•No human contact
with the part
during operation.
•Computer program
can be loaded
quickly. Shorter
runs are now
profitable.
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Laser Welding
Welded Parts
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Laser Welding
Welded car door panel made from three types of steel.
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Laser Stereolithography
(SLA)
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Part Produced by
SLA
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LASERS IN MEDICINE
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Laser Eye Surgery
LAser in SItu Keratomileusis (Lasik)
2. Laser removes tissue
from remaining cornea
to change its shape.
1. Tiny flap
of outer
cornea folded
back.
3. Flap of outer
cornea then
reattached.
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Laser Tattoo Removal
(Doesn’t always work!)
The laser beam breaks up the pigments in the tattoo
into small particles. Then the body’s immune system
attacks and destroys them.
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Laser Dentistry
Water jet
Laser
•Major advantage is no “drilling sound”.
•Can’t be used on existing metal fillings.
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LASER TESTING AND
MEASURING
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Laser Bar Code Scanning
Universal Product Code (UPC) Label
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Barcode on a UPS Label
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Barcode Scanner
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Railroad Car Sorting
Using Barcode Scanning
Labels were often too dirty for the
scanners to read.
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Laser Surface Roughness Tester
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Laser Level
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Laser Speed Measurement
New York State Police
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Telescope Calibration
Lick Observatory
The adaptive optics system at
the Shane 3 meter telescope
utilizes a 20-watt sodium laser
to put a false star in the sky.
The system uses the star to
compensate for atmospheric
disturbances, creating sharper,
clearer images of the objects
observed.
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LASER
COMMUNICATION
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Laser Printer
Corona Wire Discharge
Lamp
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Laser Disk
Pit
Land
Beam doesn’t reflect:
logical 0.
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Beam reflects:
logical 1.
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Laser Disk Drive
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MODULATION
Superimposing a weak signal
on a strong one
Audio
MODULATED LASER BEAM:
Changes in the beam represent
information in the audio signal.
Laser Carrier
MODULATOR: Combines audio
signal and laser beam.
DEMODULATOR: Removes
audio signal from the modulated
laser beam.
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FIBER OPTICS
Transparent “Pipe” for Light to Travel Through
Advantages:
• Very high capacity.
• Can’t be tapped into.
• Not affected by electromagnetic (EM) interference.
• Allows light to travel around corners.
Disadvantages:
• Expensive.
• Can be difficult to install.
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Fiber Optics
Center fiber optic cable has greater capacity
than any of these bundles of cable.
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