A relatively low-cost sensor can accurately detect, identify and track rapidly moving objects such as missiles, rocket propelled grenades (RPGs), mortars, explosive-driven fragments, bullets, shells, sports projectiles (baseballs, golf balls, tennis balls, arrows, etc.), and other types of objects. Systems that would incorporate such a sensor include military devices such as Active Protection System (APS), warning sensor systems, counter-fire systems; commercial devices such as an accurate baseball strike zone monitor, tennis ball line monitors, and arrow speed and flight characteristics monitors. The optical sensing system detects, identifies and tracks rapidly moving objects. The system is designed to be low-cost, rugged, highly reliable, and have a low False Alarm Rate (FAR). The system can accurately record signals from rapidly moving targets and then process this information with sufficient time to send a firing signal or take other action as appropriate.