ppt by shivanand iitg

1. Laser beam technology

2. 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

3. A laser beam is a powerful, narrow,
monochromatic and directional beam of
electromagnetic radiation.
Often, these beams are within the visible spectrum
of light.
A laser device excites the atoms in a lasing
medium. The electrons of these atoms move to a
higher orbit, then release photons, creating a laser
beam.

4.  The light emitted from a laser is monochromatic, that is,
it is of one color/wavelength. In contrast, ordinary white
light is a combination of many colors (or wavelengths) of
light.
 Lasers emit light that is highly directional, that is, laser
light is emitted as a relatively narrow beam in a specific
direction. Ordinary light, such as from a light bulb, is
emitted in many directions away from the source.
 The light from a laser is said to be coherent, which means
that the wavelengths of the laser light are in phase in space
and time. Ordinary light can be a mixture of many
wavelengths.
Laser Fundamentals

5. Types of lasers include gas, liquid and solid.
Gas lasers excite the electrons in gases, such as helium,
neon, cadmium, carbon dioxide and nitrogen.
 Liquid lasers include the dye laser, which uses organic
dye molecules in liquid form to produce a wavelength of
radiation that can be tuned.
 Solid lasers include the ruby laser, which uses a precious
stone to produce a beam of red light.
Types of laser

6.  Light is very focused
Light is made up of one color
(wavelength)
Light is coherent

7. Typical Lasers and Their Emission Wavelengths

8.  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.
 Excitation Mechanism
 Excitation mechanisms pump energy into the active medium by
one or more of three basic methods; optical, electrical or chemical.
 High Reflectance Mirror
 A mirror which reflects essentially 100% of the laser light.
 Partially Transmissive Mirror
 A mirror which reflects less than 100% of the laser light and
transmits the remainder.
Common Components of all Lasers

9. Lasing Action
 Energy is applied to a medium raising electrons to an unstable energy
level.
 These atoms spontaneously decay to a relatively long-lived, lower energy,
metastable state.
 A population inversion is achieved when the majority of atoms have
reached this metastable state.
 Lasing action occurs when an electron spontaneously returns to its
ground state and produces a photon.
 If the energy from this photon is of the precise wavelength, it will
stimulate the production of another photon of the same wavelength and
resulting in a cascading effect.
 The highly reflective mirror and partially reflective mirror continue the
reaction by directing photons back through the medium along the long
axis of the laser.
 The partially reflective mirror allows the transmission of a small amount
of coherent radiation that we observe as the “beam”.
 Laser radiation will continue as long as energy is applied to the lasing
medium.

10. Lasing Action Diagram
Energy
Introduction
Ground State
Excited State
Metastable State
Spontaneous
Energy
Emission
Stimulated
Emission of
Radiation

11. ATOM
PHOTONS
PHOTONS FROM EXTERNAL
SOURCE STRIKE ATOMS
IN THE ROD.
ATOMS RELEASE MORE PHOTONS
(STIMULATED EMISSION OF RADIATION)
WHICH STRIKE OTHER ATOMS CONTINUING
THE PROCESS (AMPLIFICATION).
MANY PHOTONS ARE REFLECTED
BACK AND FORTH BY THE MIRRORS
AT EACH END OF THE ROD.
COHERENT, FOCUSED PHOTONS
LEAVE THE ROD THROUGH A SLIT
IN THE MIRROR.
MIRROR
MIRROR
SLIT
LIGHT AMPLIFICATION BY THE STIMULATED EMISSION OF RADIATION

13. Theodore Maiman
First Ruby Laser
1960

14. Applications of laser beam technology
Laser beams are most commonly used in CD and DVD
devices, optical scanners, computer mice, laser
printers and pointers.
They are also used to produce holograms.
 Laser beams are used in industry to cut and weld
metal and to survey land and construct buildings.
 In scientific research, they're used in laser
spectroscopy and chemical analysis.

15.  They are used in medical procedures such as eye,
cancer and heart surgery, as well as in cosmetic
procedures.
Dental applications include cavity treatment, nerve
regeneration and reshaping gum tissue.

16. Laser welding

17. Industrial laser welding

18. Laser Guided Bomb
(“Smart” Bomb)
Optical sensor
Guidance system
Control surfaces

19. Laser Targeting
1. Laser targeting
system “paints”
target.
2. Laser guided
weapon tracks
laser spot on
target.

20. 1. Tiny flap
of outer
cornea folded
back.
2. Laser removes tissue
from remaining cornea
to change its shape.
3. Flap of outer
cornea then
reattached.
Laser Eye Surgery
LAser in SItu Keratomileusis
(Lasik)

21. • Laser light is useful in
entertainment because the
coherent nature of laser light
allows a narrow beam to be
produced, which allows the
use of optical scanning to draw
patterns or images on walls,
ceilings or other surfaces
including theatrical smoke and
fog without refocusing for the
differences in distance, as is
common with video projection.
This inherently more focused
beam is also extremely visible,
and is often used as an effect.
Sometimes the beams are
"bounced" to different positions
with mirrors to create laser
sculptures.
Laser lighting display

22. Laser Bar Code Scanning
Barcode on a UPS Label
Barcode Scanner

23.  Laser communication in space has long been a goal for
NASA because it would enable data transmission rates
that are 10 to 1,000 times higher than traditional radio
waves. While lasers and radio transmissions both travel at
light-speed, lasers can pack more data. It's similar to
moving from a dial-up Internet connection to broadband.
 Astronomers could use lasers like very accurate rulers to
measure the movement of planets with unprecedented
precision.
 With microwaves, we're limited to numbers like a meter
or two in distance, whereas [lasers have] a potential for
getting down into well beyond the centimeter range.
Space

24. Some lasers have the potential to cause
eye damage if aimed directly into the eye,
or if someone were to stare directly into a
stationary laser beam. Some high-power
lasers used in entertainment applications
can also cause burns or skin damage if
enough energy (typically a stationary
beam) is directed onto the human body
and at a close enough range.
Safety

25. Thank you