A laser is a device used to stimulate atoms or molecules to emit a narrow beam of light of specific wavelengths such as nanometers, and the radiation from it covers a specific range of visible, infrared, or ultraviolet radiation.<br />The word (Laser) is an abbreviation of the term (Light Amplification by Stimulated Emission of Radiation), and it means the amplification of light by stimulated emission of radiation, that is, the transmission of electromagnetic radiation by amplifying photons or atoms .<br />laser history<br />Albert Einstein is the first to refer to the idea of laser work in 1916 AD, when he said that atoms and molecules can be stimulated in suitable conditions to release excess energy inside them in the form of rays of light, and in 1951 AD, the scientist Charles H. Townes thought of a way to generate stimulated rays of light at microwave frequencies<br />At the end of 1953, a device appeared to show the emission of microwave frequencies from it. This device was called a maser, which means the amplification of microwave waves by stimulated emission of radiation,[1] that is, sending electromagnetic radiation by amplifying photons or atoms<br />This discovery contributed to Alexander Mikhailovich Prokhorov, Nikolai Gennadievich Basov and Charles H. being awarded the 1964 Nobel Prize in Physics<br />Types of laser<br />There are several types of laser, the most prominent of which are the following<br />gas laser.<br />. liquid laser<br />. laser fiber<br />solid laser.<br />. semiconductor laser<br /><br />By MSc Hawraa Abd Alkareem