Transcript oral+presentation+LASER[1].

Oral presentation : the LASER
I Introduction : invention of laser, lasers labels...
II Uses and applications of lasers.
III Principle and characteristics of lasers.
IV Laser safety standards and hazard classification .
I Introduction : invention of laser, lasers labels...
L ight
A mplification by
S timulated
E mission of
R adiation
Common Laser Signs and Labels
I Introduction : invention of laser, lasers labels...
Laser History
1917, Albert Einstein first theorized "Stimulated Emission.“
1954, Charles Townes and Arthur Schawlow invented the laser.
1958, they theorized about a visible laser .
1959, Theodore Maiman invented the ruby laser.
Why are Lasers important?
 Cd players
 Barcode scanners
 Eye surgery  Weapon guidance
 Fiber optic communications
…
 Laser Printers
 Laser telescopes
I Introduction : invention of laser, lasers labels...
Incandescent vs. Laser Lights.
1. Many wavelengths
2. Multidirectional
3. Incoherent
1. Monochromatic: Having the
same colour of light.
2. Directional: The paths of the
photons are very similar.
3. Coherent: The photons have
the same wave phase.
II Uses and applications of lasers.
CD player
Thin layer of aluminium
Information rolled in
a single spiral
LASER function : send an
impulse at the right time
II Uses and applications of lasers.
CD player
When a high signal appears
Digital signal : 1
When a low signal appears
Digital signal : 0
Numerical information
II Uses and applications of lasers.
Laser printer
The Laser "writes" on a photoconductive revolving drum.
The Laser receives the information from the computer
A mirror directs the Laser on the spaces to print
The paper is charged with these informations
Ink goes on the charged
spaces of the paper
III Principle and characteristics of lasers.
Common Components of all Lasers
1. Active Medium
The active medium may be solid crystals such as ruby or Nd:YAG, liquid
dyes, gases like CO2 or Helium/Neon, or semiconductors such as GaAs.
Active mediums contain atoms whose electrons may be excited to a
metastable energy level by an energy source.
2. Excitation Mechanism
Excitation mechanisms pump energy into the active medium by one or
more of three basic methods; optical, electrical or chemical.
3. High Reflectance Mirror
A mirror which reflects essentially 100% of the laser light.
4. Partially Transmissive Mirror
A mirror which reflects less than 100% of the laser light and transmits the
remainder.
III Principle and characteristics of lasers.
Common Components of all Lasers
III Principle and characteristics of lasers.
Lasing action diagram :
Excited State
Energy
Introduction
Metastable State
Ground State
Spontaneous
Energy
Emission
III Principle and characteristics of lasers.
Pulsed Output (P)
Energy (Watts)
Energy (Joules)
Continuous Output (CW)
Time
Time
III Principle and characteristics of lasers.
Today, lasers are found in many aspects of our lives. We
cannot even go the buy groceries without noticing their impact
on modern society. As time goes on people will find more and
more uses for this simple yet important light making device.
The next time one sees a laser in use, remember that at one
time a man named Charles H. Townes dreamed about it before
it was ever created. Although, many did not believe his
inventions would have much use, even he could not have
predicted how important it has become.
IV Laser safety standards and hazard classification
5 mW
5 different classes of LASERS
Class I : cannot emit laser radiation in excess
of the maximum permissible exposure levels
Class II : Do not causes damages unless seen intentionally
for more than 0.25 seconds.
Class IIIa : could cause spot blindness and other possible eye injuries
if looked at directly
Should have a Danger label
Class IIIb : will cause eye damages and maybe skin hazard
could make flammable products take fire
1W
Class IV : will cause eye and skin damage
will cause materials to burn
CONCLUSION
Discovery of public research.
Personal investigation and experimentation.
Knowledge learned before very useful.