Introduction to lasers and different types of lasers.
Light is a form of energy that can be released by an atom. It is made up of many small particle-like packets that have energy and momentum but no mass. These particles, called light photons, are the most basic units of light.
Atoms release light photons when their electrons become excited. If you've read How Atoms Work, then you know that electrons are the negatively charged particles that move around an atom's nucleus (which has a net positive charge). An atom's electrons have different levels of energy, depending on several factors, including their speed and distance from the nucleus. Electrons of different energy levels occupy different orbitals. Generally speaking, electrons with greater energy move in orbitals farther away from the nucleus. When an atom gains or loses energy, the change is expressed by the movement of electrons. When something passes energy on to an atom, an electron may be temporarily boosted to a higher orbital (farther away from the nucleus). The electron only holds this position for a tiny fraction of a second; almost immediately, it is drawn back toward the nucleus, to its original orbital. As it returns to its original orbital, the electron releases the extra energy in the form of a photon, in some cases a light photon.
The earliest stimulated-emission device developed in 1954, it was a microwave maser, the Nobel prize was won for it in that year.Workers in the engineering industry then endeavoured to extend the maser use from microwaves to light wavelengths.
In 1960 T.H Maiman demonstrated the first laser, using a ruby rod as the active element.
The Difference between the lasers and other light sources is that the laser light source material provides a particular form of energy state in which the excited atoms pause before returning to their ground state(metastable state).they remain in this state until stimulated into returning to ground state.