The course introduces fundamental principles of laser generation and properties of laser radiation at intermediate level of the BSC degree program –laser theory "emission and absorption of light- stimulated emission-Einstein relations- population inversion- threshold gain coefficient" laser energy level systems " two , three, and four levels system", properties of laser radiation , optical resonators, operational of practical laser "Laser types: solid state lasers (ruby laser and Nd: YAG laser)- gas lasers (HeNe laser and carbon dioxide laser), liquid lasers (Dye laser), and Semiconductor lasers, laser applications.