The A6D-3100 is a series of photoelectric sensors from Omron. It is a retro reflective photoelectric sensor which detect the presence of an object by sending out a modulated light beam, and then detecting its reflection from the targeted object. The A6D-3100 series features a built-in time-delay circuit, as well as a multi-turn potentiometer for sensitivity adjustment. It is designed using the latest advanced chip technology to ensure reliable performance and a long life span. The A6D-3100 series is available in 2 switch forms (NPN and PNP), and with either a visible red light or an invisible infrared light depending on the desired sensing range.