Laser Helium-Neon Lasers. Only carbon dioxide lasers

Laser are classified into various categories to cope with
the market trends. You can have a particular laser matching with the industry e.g.
medical industry has its own range of laser. A general categorization of laser
is listed below

1.      
Gas lasers

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2.      
Dye lasers

3.      
Solid state lasers

 

1.   
Gas Lasers:

You will find a common pump source in all gas laser that is
electricity. Gases are used in excited states directly or indirectly. In direct
mode it collides with electrons whereas in indirect mode it collides with other
gases.

Gas laser is very useful to mark the optical spectrum from ultraviolet
to far infrared. As gas laser emit narrowly so no continuous spectrum
possibility is found. Here is a types of laser from ultraviolet to infrared

a)      
Corban dioxide lasers.

b)     
Argon-ion lasers.

c)      
Excimer lasers.

d)     
Helium-Neon Lasers.

 

Only carbon dioxide lasers are really efficient from 15 to
20% because they are used mostly in industry for material processing. Other UV
to IR lasers have mostly less efficiency of less than 1% in most cases.

2.   
Dye lasers:

Dye lasers use optical source for pumping. They basically
use organic materials which emit in visible spectrum and then are colored.
Molecules of them are then diluted in a solvent like ethylene glycol, methanol
but usually an alcohol is used.

Visible spectrum in case of dye lasers is completely covered.
Because the dyes are very complex organic molecules that have many levels of
energy. Which are very close to each other that they are considered as an
energy band as a whole. Generally, a molecules of dyes lasers continuously
covers the entire visible spectrum. Against these properties, dye lasers are
used because their implementation is inappropriate to prevent the molecules
from being destroyed by the pumping source, where dye from reservoir keep
circulating in the pumping zone.

 

3.   
Solid state lasers

Solid state lasers are either semiconductor lasers or diodes
which are pumped electrically or those lasers which are crystalline or glass
matrix are pumped optically.

Diode Lasers:

Diode lasers basically use recombination’s between
the electron-hole pairs which are found in the semiconductors to emit light in
the form of invigorating emission. Pumping source is electrical with the
efficiency which can be reached to 60%. These are the most efficient and
reliable lasers available. Their power can reach several kilowatts by putting
them together in hundreds of diode lasers and combining them in the same
optical fiber. the disadvantage of these diode lasers is the poor quality of
the beam emitted by them and also at one pulse rate they cannot operate.

Advantages

Following are the advantages of solid state
lasers:

                                
I.           
There is no chance of the material wastage where
this occurs. Because in the active medium material used is in solid form.
Wastage of material only takes place in gas form.

                              
II.           
In this laser the output is continuous as well
as pulsed.

                            
III.           
They have high efficiency than gas lasers.

 

Disadvantages

                                
I.           
Solid state laser efficiency is very low as
compared to carbon dioxide lasers.

                              
II.           
Due to thermal lasing the power loss occurs when
the rod gets very hot.

                            
III.           
Great disadvantage is the divergence, which is
not constant.