A touch system with a curved touch surface, including light emitters projecting light beams over and across the curved surface, such that at least some of the light beams are incident upon and reflected by the curved surface, light detectors detecting reflections, by a reflective object touching the curved surface, lenses mounted such that (i) there is a particular angle of entry at which each light detector receives a maximal light intensity, and (ii) there are target positions, associated with emitter-detector pairs, on the curved surface, whereby light beams emitted by the light emitter of that pair are reflected by the object into the lens corresponding to the light detector of that pair at the particular angle of entry, and a processor calculating a location of the object touching the curved surface by determining an emitter-detector pair that detects a maximal amount of light, and identifying the associated target position.