deflects part of the beam back to the receiver. Detection occurs and output is turned on or off when sufficient light falls on the receiver. Some photo-eyes have two different operational types, light operate and dark operate. The light operates photo eyes become operational when the receiver "receives" the transmitter signal. Dark operate photo eyes become operational when the receiver "does not receive" the transmitter signal. The detecting range of a photoelectric sensor is its "field of view", or the maximum distance from which the sensor can retrieve information, minus the minimum distance. A minimum detectable object is the smallest object the sensor can detect. More accurate sensors can often have minimum detectable objects of minuscule size. Difference between modes See also List of sensors Photodetector Sensor Electric eye References External links Guide to Sensing, 2002, Banner Engineering Corporation, P/N 120236 Guide to sensing Sensors