Omron Electronics EE-SY199 and EE-SY171 Series Photomicrosensors are RoHS compliant, non-amplified, reflective microsensors. Omron photomicosensors, or photointerrupters, sense objects or object positions with an optical beam. When an object is located in the sensing area of the reflective photomicrosensor, the object reflects the optical beam of the emitter, changing the amount of optical energy reaching the detector. Omron EE-SY199 is an ultra-compact, PCB surface mount type. with a sensing distance of 1mm. Omron EE-SY171 is a 3-mm tall, thin model with a sensing distance of 3.5mm.