In one aspect, an object detection system is provided that adapts to the distance between the emitter and receiver. The system may utilize a range determining operation whereby the receiver will adjust an operation threshold, such as the detected signal strength required for the receiver to indicate that no object is present. The system may increase the threshold of the receiver as the strength of the received signal from the emitter increases, and upon certain conditions, decrease the threshold of the receiver as the strength of the received signal decreases. The system may utilize different receiver thresholds corresponding with different distance ranges between the emitter and receiver. By increasing the threshold of the receiver, the system may disregard low-level reflected light, thereby avoiding ignoring legitimate obstructions, while allowing the system to operate reliably over a wide physical range between the emitter and receiver.