Preview referat: Laser
Once started the reaction propagates as pyramidal form, a photon emitted by one atom to another dezexcitat will trigger thereaction, this in turn will emit a photon and will release on theincident. We have two photons which will increase exponentially.This produces an amplification of light radiation.Practical realization of laser devices. Types of laser.
Constituent parts of a laser are the active medium, resonatorsystem and optical excitation. Essential part of a laser device is the active medium, ie an environment where there are atoms are in a high energy state of equilibrium. In this environment activeradiation light amplification occurs (if we have an incident lightradiation) or radiation emission and amplification of light (if youdo not have an incident light radiation).
The excitement isnecessary to obtain systems
atomic with atoms in a high energy state. There are several ways to achieve excitation of atoms in the active medium, depending on the nature of the environment. Optical resonator is a system of lenses and mirrors needed for processing optical radiationemitted. Although the laser beam output from the active mediumare almost perfectly parallel optical resonator is used for more precise collimation, to concentrate rays to a point calculated forthe dispersion of rays and other necessary applications.
After the active nature of the environment distinguish several types of laser. Among these we find the ruby laser, ruby bar thatdistinguish treated as the active medium and mirrors plus all light source is often used as the excitation system. Gas laser usingrare gas mixtures (He, Ne, Ar, Kr) or CO2 as the active mediumand a power source connected to two electrodes take the role ofthe excitation system. « mai multe referate din Engleza