Excimer Laser , construction , working , Advantages , Disadvantages , Application

               -: Excimer Laser :- 

Excimer laser is pulsed mode gas laser in which a mixture of a rare gas and a halogen as an active medium are used .

                                  Basically excimers are molecules which exits only in the excited state , the populations of the ground state of the molecules are always zero . Hence it is relatively easy to obtain population inversion and acquire high efficiency . The excimer lasers operate mainly in the ultraviolet region which is the mixture of rare gases such as argon , krypton or xenon with halide molecules chlorine or fluorine . 
                                  The commonly used excimer lasers with their wavelength are argon fluoride laser at 193nm , krypton fluoride  laser at 248nm etc . 

Construction :- 

                         The whole structure of excimer laser is made of laser . A typical excimer laser is shown in figure . Electric discharge takes place in the transverse direction to achieve population inversion . 

image Source : Google

Image Source Google

Working :- 

                 The laser gas is mixed with helium gas so that the mixture has a pressure of about 2-4 atmospheric pressure . Excitation occurs by electron dissociation and ionization of the gas molecule to produce argon , krypton , xenon ions . These ions react with the halide molecules pulling off one of the atoms of that molecule to make excite diathermic molecule also called the excimer molecule , i.e. molecules which represent a bound state . The excitation must be for a very short time and with a very high power . 

Advantages of Excimer Laser :- 

1- The excimer laser typically produce short pulses of peak power 10-20 MW with repetition rates of up to 1000 pulses per second . 

2- These lasers are very efficient and provide useful energy in the wavelength regions where other types of powerful lasers are not available . 

Disadvantages / Drawbacks of Excimer Laser :- 

1- The high voltage requirement of excimer laser is dangerous .

2- Due to multimode operation of excimer laser , it is not of good quality as compared to other lasers . 

3- There is a risk in eye damage , skin cancer because it operates with ultraviolet beam . 

Applications of Excimer Laser :- 

1- Excimer Laser are widely used for laser surgery . 

2- Excimer Laser are widely used in drilling holes in metallic objects .

3- Excimer Lasers are used for pumping in dye lasers . 

4- Excimer Lasers are also used in Lithography .