A lens for placement opposite a diode in an optical touch sensor, including an upper portion including an upper refractive surface located nearer to the diode, and an upper reflector located further from the diode, the upper reflector being curved in two dimensions and cut horizontally by a top horizontal plane of the lens, and a lower portion, coplanar with the diode, including a lower refractive surface located nearer to the diode, and a lower reflector located further from the diode, the lower reflector being curved in the two dimensions and cut horizontally by a bottom horizontal plane of the lens, wherein the upper and the lower reflector are symmetrical and vertically aligned, and wherein non-collimated light reflected by the lower reflector onto the upper reflector is partially collimated in the two dimensions by the lower reflector and further collimated in the two dimensions by the upper reflector.