A proximity sensor including a structure suspending at least one lens above a circuit board, light emitters operable to project light beams through the lens along a common projection plane, light detectors operable to detect amounts of light arriving through the lens at the detector, wherein an object in the projection plane reflects light from an emitter to one or more of the detectors, and wherein each emitter-detector pair, including one of the emitters and one of the detectors, when synchronously activated, is expected to generate a greater detection signal at the activated detector than the other detectors, were they to be synchronously activated with any of the emitters, when the object is located at a specific 2D location in the projection plane corresponding to the emitter-detector pair, and a processor identifying gestures performed by the object based on amounts of light detected by the detector of each emitter-detector pair.