TCRT5000 IR SENSOR LED PAIR are used in many of the Arduino modules sold for obstacle detection and avoidance or for line following robots. They can be used for applications where it is desirable to detect an object passing in front of the sensor at close range. The sensor incorporates both an IR emitter LED which is blue in color and an IR phototransistor receiver that looks black in the same package. The emitter operates in the infrared range of 950nm and the receiver has a daylight blocking filter to help minimize interference from visible light.