A modular proximity sensor including a plurality of sensor modules, each sensor module including a housing, lenses, light detectors, each detector positioned along the image plane of a respective lens so as to receive maximum light intensity when light enters the lens at a particular angle, light emitters, each emitter positioned in relation to a respective lens so as to project light into a detection zone, an activating unit synchronously co-activating each emitter with at least one of the detectors, and a calculating unit receiving detector outputs corresponding to amounts of projected light reflected by an object in the detection zone, and calculating a two-dimensional location of the object in the detection zone based on the detector outputs and the particular angle, wherein neighboring sensor modules monitor different detection zones, and a processor receiving outputs from each sensor module and mapping the object location in multiple detection zones over time.