has function light emission function light emission device light source A light source is an optical subsystem that provides light for use in a distant area using a delivery system (e.g., fiber optics). Light sources may include one of a variety of lamps (e.g., xenon, halogen, mercury). Most light sources are operated from line power, but some may be powered from batteries. They are mostly used in endoscopic, microscopic, and other examination and/or in surgical procedures. The light source is part of the optical subsystem. In a flow cytometer the light source directs high intensity light at particles at the interrogation point. The light source in a flow cytometer is usually a laser. Elizabeth M. Goralczyk John Quinn Olga Tchuvatkina Practical Flow Cytometry 4th Edition, Howard Shapiro, ISBN-10: 0471411256, ISBN-13: 978-0471411253 light source metadata incomplete