Infrared Photoreflector sensor contains two elements, one that emits a beam of infrared light and the other, which detects that light. An object in front of this sensor will reflect light. Daylight filter is built in to reduce interference from ambient lighting. Optimal sensing distance is about 0.2 inches.

This sensor can be used as a downward-looking detector to detect the edge of competition ring or to detect a line to follow.

Datasheet
Fairchild QRB1134 IR Photoreflector (.pdf 48 Kb)