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# Laser

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```INTRODUCTION TO LASERS
TECHNOLOGY EDUCATION
SCARSDALE MIDDLE SCHOOL
LASER PRESENTATION
1
Many of the pictures for
this “LASER” presentation came
from www.howstuffworks.com.
LASER PRESENTATION
2
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.
LASER PRESENTATION
3
The Atom
Different electron orbits represent different energy levels.
LASER PRESENTATION
4
The Electron
Applying energy to an electron causes it to jump
to a higher orbit.
LASER PRESENTATION
5
The Photon
When the electron drops back to its original orbit it
releases a particle called a photon. Light is made up
of photons.
LASER PRESENTATION
6
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
LASER PRESENTATION
7
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
LASER PRESENTATION
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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
LASER PRESENTATION
9
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.
LASER PRESENTATION
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Light Bulb
Light is not focused
Light is made up of many colors (wavelengths)
Light is not coherent
LASER PRESENTATION
11
White Light
Light From A
Light Bulb
•All colors
(wavelengths).
•More longer
wavelengths.
•Light is not
coherent.
•Light is not
focused.
LASER PRESENTATION
12
Laser Light
Light is very focused
Light is made up of one color (wavelength)
Light is coherent
LASER PRESENTATION
13
Laser Light
Light From A
Laser
•One color
(wavelength).
•Light is
coherent.
•Light is focused.
LASER PRESENTATION
14
Theodore Maiman
First Ruby Laser
1960
LASER PRESENTATION
15
How a Laser Works
LASER PRESENTATION
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Ruby Laser
LASER PRESENTATION
17
Types of Lasers
Based on the Material Used in the Laser
Classes of Lasers
Based on the Biological Damage the Laser
Can Cause
LASER PRESENTATION
18
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)
LASER PRESENTATION
193
248
337
488
514
543
633
570 - 650
694
1064
10600
19
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.
LASER PRESENTATION
20
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.
LASER PRESENTATION
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LASER WEAPONS
“Do you expect me to talk Goldfinger?”
“No Mr. Bond, I expect you to die.”
LASER PRESENTATION
22
Laser Gun Sights
LASER PRESENTATION
23
Multiple Integrated Laser Engagement System
MILES (2000)
“Laser Tag” for Soldiers
LASER PRESENTATION
24
Laser Targeting System
Aircraft Mounted
LASER PRESENTATION
25
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.
LASER PRESENTATION
27
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.
LASER PRESENTATION
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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.
LASER PRESENTATION
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ABL
Airborne Laser
Antimissile Weapon
United States Air Force
LASER PRESENTATION
31
ABL
Nose Turret
CO2 Targeting Laser
LASER PRESENTATION
32
LASERS IN MANUFACTURING
LASER PRESENTATION
33
Punch Press
Typical Stamped Parts
Punch Press Problems
•Dangerous to operate.
•Required long runs
to be profitable.
LASER PRESENTATION
34
Laser Cutter
LASER PRESENTATION
35
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.
LASER PRESENTATION
36
Laser Welding
Welded Parts
LASER PRESENTATION
37
Laser Welding
Welded car door panel made from three types of steel.
LASER PRESENTATION
38
Laser Stereolithography
(SLA)
LASER PRESENTATION
39
Part Produced by
SLA
LASER PRESENTATION
40
LASERS IN MEDICINE
LASER PRESENTATION
41
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.
LASER PRESENTATION
42
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.
LASER PRESENTATION
43
Laser Dentistry
Water jet
Laser
•Major advantage is no “drilling sound”.
•Can’t be used on existing metal fillings.
LASER PRESENTATION
44
LASER TESTING AND
MEASURING
LASER PRESENTATION
45
Laser Bar Code Scanning
Universal Product Code (UPC) Label
LASER PRESENTATION
46
Barcode on a UPS Label
LASER PRESENTATION
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Barcode Scanner
LASER PRESENTATION
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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
LASER PRESENTATION
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Laser Level
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51
Laser Speed Measurement
New York State Police
LASER PRESENTATION
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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
LASER PRESENTATION
54
Laser Printer
Corona Wire Discharge
Lamp
LASER PRESENTATION
55
Laser Disk
Pit
Land
Beam doesn’t reflect:
logical 0.
LASER PRESENTATION
Beam reflects:
logical 1.
56
Laser Disk Drive
LASER PRESENTATION
57
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.
LASER PRESENTATION
58
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.
LASER PRESENTATION
59
Fiber Optics
Center fiber optic cable has greater capacity
than any of these bundles of cable.
LASER PRESENTATION
60
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