The SICK WL11-B560 is a retro-reflective photoelectric sensor from the versatile WL11 series. It is designed for reliable object detection at medium to long ranges. This sensor operates by emitting a light beam (invisible infrared in this case) towards a dedicated reflector. The reflector bounces the beam directly back to the sensor's receiver. An object is detected when it breaks this beam path, preventing the light from returning to the sensor.