Laser is an acronym for light amplification by stimulated emission of radiation. In the last century many types of lasers have been used for many different applications from welding to surgery to military and even many uses in every day life by harnessing the principles of light and stimulated emission. To understand how lasers work we must first understand the physics behind light waves. Light is emitted from a source and travels in straight lines and when it strikes an object is either absorbed, reflected, or refracted. Light behaves primarily like a wave and its this wave nature of light that allows lasers to work. Constructive interference is what amplifies light. Since li