Beginning of Essay
The laser is a device that a beam of light that is both scientifically and practically of great use because it is coherent light. The beam is produced by a process known as stimulated emission, and the word "laser" is an acronym for the phrase "light amplification ....

Middle of Essay
.... essentially a single frequency but also coherent, with the light waves all moving along in unison. Lasers consist of several components. A few of the many things that the so-called active medium might consist of are, atoms of a gas, molecules in a liquid, and ions in a crystal. Another component consists of some method of introducing energy into the active medium, such as a flash lamp for example. Another component is the pair of mirrors on either side of the active medium which consists of one that transmits some of the radiation that hits it. If the active component in the laser is a gas laser than each atom is characterized by a set of energy stat ....