A general-purpose, surgical, light (optical) magnification instrument, usually stereoscopic, designed to magnify minute structures, e.g., nerves or vessels in the performance of delicate surgical procedures which require high magnification by transmitted light. An operating microscope will often be equipped with motorized focusing, adjustable magnification mechanisms (manual, zoom or both), backup lamps, and inclined tubes that permit the surgeon to see the field from a vertical perspective while keeping the head erect. Dual or multiple observation capability and the optical integration of still, motion picture and video cameras are common features. It can be fixed or mobile.