A method for identifying a proximal object, including providing light emitters, light detectors and lenses, mounted in a housing, each lens, denoted L, being positioned in relation to a respective one of the detectors, denoted D, such that light entering lens L is maximally detected at detector D when the light enters lens L at an angle of incidence θ, activating the detectors synchronously with activation of each emitter to measure reflections of the light beams emitted by each emitter, and calculating a location of a reflective object along a path of a light beam projected by an activated emitter, by calculating an axis of symmetry with respect to which the outputs of the synchronously activated detectors are approximately symmetric, orienting the calculated axis of symmetry by the angle θ, and locating a point of intersection of the path of the emitted light beam with the oriented axis of symmetry.