24-12-2012, 06:21 PM
Lasers
Lasers.pptx (Size: 73.35 KB / Downloads: 35)
Essential components of a laser system :
Active medium or Gain medium : It is the system in which population inversion and hence stimulated emission (laser action) is established.Pumping mechanism : It is the mechanism by which population inversion is achieved.i.e., it is the method for raising the atoms from lower energy state to higher energy state to achieve laser transition.
DIFFERENT PUMPING MECHANISMS :
i. Optical pumping : Exposure to electromagnetic radiation of frequency = (E2-E1)/h obtained from discharge flash tube results in pumping Suitable for solid state lasers.
ii. Electrical discharge : By inelastic atom-atom collisions, population inversion is established.
Suitable for Gas lasers
Chemical pumping : By suitable chemical reaction in the active medium, population of excited state is made higher compared to that of ground state Suitable for liquid lasers.
Optical resonator : A pair of mirrors placed on either side of the active medium is known as optical resonator. One mirror is completely silvered and the other is partially silvered. The laser beam comes out through the partially silvered mirror.