This document presents information about a helium-neon laser from a group including Raja Afrasiyab Siddique. It defines a laser as a device that emits light through optical amplification based on stimulated emission. It describes how the helium-neon laser works using a population inversion between energy levels in helium and neon atoms, producing a visible red light. Applications include bar code scanners, measuring tools, and holography.

1. Presented by :
• RAJA AFRASIAB SIDDIQUE
(Group leader)
(785-FBAS/MSCPHY/F-17)
• HASSAN AFZAL
(772-FBAS/MSCPHY/F-17)
• RAMZAN HUSSAIN
(756-FBAS/MSCPHY/F-17)
• SHAHZAIB GONDAL
(777-FBAS/MSCPHY/F-17)
Presented to :
• Sir TUFAIL MUHAMMAD

3. 1) Abbreviation
2) Definition of LASER
3) Concept of LASER
4) Invention of LASER
5) Principle of LASER
6) Different types of LASER
7) HELIUM – NEON LASER
8) Diagram of he –ne LASER
9) Construction
10) Working and Energy level diagram
11) Properties
12) Application
13) Advantages
14) Disadvantages
END

4. LASER Stand for “Light
Amplification By stimulated
Emission Of Radition.”

5. “A Laser is a device that
emits light through a
process of optical
amplification based on the
stimulated emission of
electromagnetic radition.”

6. Albert Einstein , was the first man
who gave the concept of LASER in
1917
He postulated that, “when the
population inversion exists between
uper and lower levels among atomic
systems, it is possible to replize
amplified stimulated emission and
stimulated emission & stimulated
emission has same frequency and
phase as the incident radiation”

7. The first LASER was built in
16 MAY 1960 by Theodore
Maiman at the Hughes
Research Laboratory in
California, based on the the
theoretical work by Charles
Hard Townes and Arthur
Leonard Schwlow.

8. The principle of a LASER is
based on three separate
features,
1. Stimulated emission with in an
amplifying medium.
2. Population inversion of
electrons.
3. An optical resonator.

10. Definition:-
“He – Ne LASER is a type of Gas
LASER whose gain medium
consists of a mixture of 85%
Helium and 15% Neon inside
of small electrical discharge.”

11. One of the most common Gas
LASER is called Helium-Neon
, because one of the Spectral
Lines emitted by this LASER
lies in Visible region having
Wavelength 632.8 nm.

13. ❖ The He-Ne is a gas LASER.It is
produce inside along quartz tube
having mirrors at both ends.One end
is made totally reflecting and the
other end is partially transparent
.The LASER beams come out
through partially transparent mirror.
❖ The tube has Helium 85% and Neon
15%.
❖ The Helium behaves as pumping
medium and Neon acts as active
medium.

14. ENERGY LEVEL DIAGRAM:

15. Explanation :-
➢ The three energy level E0,E1,E2
OF Ne and one energy E3 of He
are involved in the LASER
action.The energy level E3 of He
having energy 20.61ev is
metastable.The energy level E2 of
Ne having energy 20.66ev is also
metastable.Both have nearly
identical metastable state.

16. ➢ The pumping is done by electric
discharge in He-Ne mixture. The
ELECTRONS and IONS collide with He
and Ne ’ atoms and rise them to Energy
level E3.The excitation energy of helium
is transfered to neon during collision
because energy level E3 and E2 have
identical energies.
➢ In this way level E3 of Neon becomes
more highly populated then level E1 of
Neon having energy 18.70ev. This is
callad POPULATION
INVERSION.

17. ➢ This population inversion is maintained
because metastability of level E3 of
Helium ensures already supply of Neon
atoms in level E2 and level E1 decays
rapidly to Neon ground state E0.
➢ The stimulated emission from level E2
to level E1 predominate and Red LASER
Light of wavelength 632 nm having
energy 1.96ev is generated.
➢ The Photons emitted in this stimulation
process move back and forth through
discharge tube and make reflections
from mirror M1 and M2 and start a
chain reaction.

18. ❑ LASER Type : Gas
❑ Pump Source : Electrical
Discharge
❑ Operating Wavelengths :-
1. 623.8 nm
2. 543.5 nm
3. 593.5 nm
4. 611.8 nm

19. ➢ He-Ne is used widely in
Commercial and Industrial
applications, and commonly used
in Lab. Demonstrations of optics.
➢ It is the most common LASER
used in HOLOGRAPHY.
➢ Other major applications of He-
Ne LASER include :

20. o Bar Code Scanner
o Tool Alignment
o Non-Contact measuring and
monitoring.
o Blood Analysis
o Particle counting and Food
sorting
o Alignment of high power CO2
and pointing beams
o Military purposes (Weaponry)

21. 1) He-Ne LASER has very good
Coherence property.
2) Cost of He-Ne LASER is less from
most of other LASER.
3) Construction of He-Ne LASER is
also not very Complex.

22. 1) It is relatively low power device
means its output power is low.
2) He-Ne LASER is low gain system
/device.
3) High Voltage requirement can be
considered its disadvantage.
4) Escaping of gas from LASER
Plasma tube is also its advantage.