A device that releases a beam of coherent light through optical amplification is called a laser. Laser stands for light amplification by stimulated emission of radiation. There are various components of a laser. It consists of gain medium, high reflector, laser pumping energy, laser beam and output coupler. The scientific study of theory and practice of lasers is known as laser science. Lasers have high temporal coherence. It allows them to emit light with a narrow spectrum. Laser beam profiler is used in measuring width, divergence and intensity profile of laser beams. Various types of lasers include gas lasers, semiconductor lasers, solid-state lasers, etc. Lasers are used in weapons, DNA sequencing instruments, printing, cutting and welding, lithography, small hand-held devices like laser pointers, etc. Laser medicine is the use of laser in medical diagnosis, treatments and therapies such as laser mammography, laser hair removal, laser surgery, etc. This book provides comprehensive insights into the field of laser science. Some of the diverse topics covered herein address the varied branches that fall under this category. This book is meant for students who are looking for an elaborate reference text on lasers.