The F3SG-4RE1520P14 is a safety light curtain (photoelectric switch) manufactured by Omron. It is made up of two main components – a light receiving unit and a light emitting unit, which are connected by a connection cable. The controller in the light receiver uses an internal diode to control the voltage drop when two beams of light cross each other between the light emitter and the receiver. When someone breaks the two light beams, it creates an interruption and an output signal is generated from the receiver. This output signal can then be used in a variety of safety applications such as door opening systems or safety fences. The F3SG-4RE1520P14 has a range detection of 1.5-20 meters and a 15mm resolution, making it ideal for medium to long-distance detection applications. It is rated IP67 and IEC/EN 60947-5-2 compliant, making it suitable for use in industrial environments.