PRESENTED BY:shivam pandey

LASERS

L L LightAA Amplification bySS StimulatedEE Emission of RR Radiation

A laser is a device that A laser is a device that transforms light of various transforms light of various

frequencies into a frequencies into a chromatic radiation in the chromatic radiation in the

visible, infrared, and visible, infrared, and ultraviolet regions with all ultraviolet regions with all

the waves in phase the waves in phase capable of mobilizing capable of mobilizing

immense heat and power immense heat and power when focused at close when focused at close

range.range.

WHAT IS A LASER ?

CHARACTERISTICS OF LASER COHERENCE HIGH INTENSITY HIGH DIRECTIONALITY HIGH MONOCHROMATICITY

1 COHERENCE :The wave trains which are identical in phase and direction are called coherent waves.

2 High intensity :Due to the coherent nature of laser, it has the ability to focus over a small area of 10

3 High directionality :The angular spread of a laser beam 1mm/meter.

4 High monochromaticity :

The light from a normal monochromaticity source spread over a range of wavelength of the order 100nm.but, the spread is of the order of 1nm for laser.

Stimulated and spontaneous

Stimulated It is not a random

process. The photon get

multiplied through chain reaction.

t is a controllable process.

More intense. Monochromatic

radiation.

Spontaneous It is random process. The photon do not get

multiplied through chain reaction.

It is a not controllable process.

Less intense. Polychromatic radiation.

9

LASER

ND: YAG LASER

CONSTRUCTION :

Nd yag rod and krypton flash lamp are enclosed inside in ellipsoidal reflector.

In order to make the entire flash radiation to focus on the laser rod.

The nd yag rod is placed t one focal axis and the flash lamp at the other focal axis of the ellipsoidal reflector.

Energy level Diagram

E0

Non-radiativetransition

Ground State

Metastablestate

E2

E3

E1

E4

1.06

4 µm

0.73

µm

0.80

µm

laser

Non-radiativetransition

working The flash lamp switched on. The optical pumping excites the ions from the

ground energy state E0 to the higher energy level E3 and E4 by absorbing radiation .80µm and .73µm,respectively.

The energy level E4 to E2 is the non radiative transition.

The E2 state is meta stable state. Any of the spontaneously emitted photon will

make the excited ion to undergo a transition between E2 E1 state.

The transitions E2 E1 yields an intense and coherent laser beam of wavelength 1.064µm.

These laser give beam continuously. The ions then make a transition between E1 E0. The flash lamp is used to excite the ions, while the

rest heats up the crystal. Thus, the system can be cooled by either air or

water circulation.

APPLICATION OF LASERA) In industry :1) For welding and melting.2) For cutting and drilling holes.3) To test the quality of the material.

B) IN medicine :1) Used for treatment of detached retinas.2) Used in performing micro and bloodless surgery

C) Military applications :1) The laser beam can serve as war weapon,i.e. A power full laser beam can be used to destroy in few second, the big size object like aeroplanes, missiles etc.

D) Science and engineering application :

1)Fiber optic communication.2)It is used to holography.3)Communication between planets is possible with laser.

4) It is used to accelerate some chemical reaction.5) It is used to drill minute holes in cell walls without damaging the cell itself.

Laser OutputContinuous Output (CW) Pulsed Output (P)

                       

watt (W) - Unit of power or radiant flux (1 watt = 1 joule per second).

Joule (J) - A unit of energy

Energy (Q) The capacity for doing work. Energy content is commonly used to characterize the output from pulsed lasers and is generally expressed in Joules (J).

Irradiance (E) - Power per unit area, expressed in watts per square centimeter.

Ener

gy (W

atts

)

TimeEn

ergy

(Jou

les)

Time

Common Laser Signs and Labels

Thank you