LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION
Laser is widely used in each and every field in this modern era.
First, I will tell you how it's work and what is the mechanics behind the laser. I'll start from scratch.
Here we go,
There are three main things that occurs when we give energy to the atom. And that energy could be in the form of radiation.
If you are science student,then you definitely know that when we emitt some energy in the form radiation or photon on atom,it has tendency to absorb that energy and become excited.in atom,we assume that there are different states like ground state where the atom has lowest energy and other state like excited state,if atom absorb energy that it would tend to go in excited states.
2:) Spontaneous emission:
After absorption of energy ,atoms have tendency to emit some light.As soon as atom get excited it would tend to go in excited states and there it will stay for 10^-8 sec.and while it come back to ground state,it emitt some energy in the form photon.so far so good, whatever we have learnt which is not enough to explain how laser works?
The main principle is yet to be explained.
3:) Stimulated emission
This emission is the main principle of laser.without this we couldn't get laser light.so let's try to understand,
As i said when atom get excited, it tends to go in excited states just like spontaneous emission but slightly different phenomena occurs here,while atom coming back to ground state,again we emitt photon on that and atom absent it and it would emit two coherent photon instead of one photon just like in spontaneous emission.In this emission we would get two photons which are in phase,and these phenomena repeat several time, that's why we have lots photons which are same phase, because of this intensity of light gradually increase.
Let's talk about what are things we need to construct a laser.
1:- Active material
2:- Pumping system
3:-Cooling system(Not necessary in som case)
4:-Optical cavity or resonator
Let's talk about first laser which was invented by T.h namin which is rubby laser.
Al2O3+0.05%Cr used as Active material.
Pumping system:- Xe or Kr lamp used to give energy to that material.
Here,we need cooling system in order to control the temperature of laser.
This laser has drawback ,that it does't gives continuous laser instead of that it gives pulse laser.
So That's why we need continuous laser now we do have that kind of laser.
In this laser we use He-Ne (10:1) gases and it is our Active material.
We use gases as Active material so this kind of laser called gas laser.
Here we don't need any kind of cooling system because here we use electric pumping system as shown in figure. That's how the gase discharge in tube because of high potential between anode and cathode.
This is why we get continuous laser.
Application of Laser light
-Laser widely used in medical field for eye operations and other operations.
-Defence Area like in weapons and ladar(laser detection and ranging)
-Long distance measurement
Apart from this,There are several use of laser.
This is all about laser, thanks for reading.