ABSTRACT
This chapter provides an overview of processes and parameters relevant to the laser. At first glance, a laser seems simple enough: an amplifier pumped by some means, and surrounded by two mirrors—one of which is partially transmitting—from which an output beam emerges. Once the most popular visible laser, it has been replaced in many applications by smaller and cheaper semiconductor diode lasers. In a practical laser, a single photon of radiation passes through the amplifier many times, with the flux of photons becoming more powerful on each pass and eventually building to power where a usable beam results. Low-gain amplifiers require high-reflectivity mirrors—an example being the helium-neon gas laser, which commonly has a high reflector of almost 100% reflectivity and an of output coupler (OC) about 99% reflectivity. The main components consist of a pump, a tiny vanadate crystal mounted on a copper disk, and an OC cavity mirror.
