The QTRX-HD-03RC Reflectance Sensor Array, part of the Pololu QTR Series, is a high-density infrared (IR) reflectance sensor array that is suitable for detecting small objects and sensing an object's position and shape. The QTRX-HD-03RC has three sensor channels, each with five synchronous LED sources and phototransistors to sense reflectance. The LED/phototransistor configuration allows for reliable detection, even from a distance, and at angles away from the array. The QTRX-HD-03RC measures 15.4mm x 12.4mm and features an easy-to-use, 0.1" linear pitch connector interface. The onboard LEDs offer excellent ambient light immunity for operation in challenging environments.