An optical encoder is a device that converts the position or movement of an object into an electrical signal. It uses light to detect changes in position, typically employing a light source and a sensor. When the object moves, it interrupts or reflects the light, allowing the encoder to determine its position or speed. These encoders are commonly used in various applications, such as robotics, industrial automation, and computer peripherals. They provide precise measurements and are essential for tasks that require accurate control, like in servo motors and CNC machines.