This invention relates to an improved design for the transmit and receive optical elements of a waveguide-based optical touch screen sensor, where at least one converging lens is incorporated within the body of each transmit and receive element. The optical elements of the improved design are more mechanically robust, easier to incorporate into the touch screen assembly, and are less susceptible to stray light and the ingress of foreign matter. In one embodiment the converging lens collimates the light into a plane wave. In another embodiment the converging lens focuses the light to an external point. In yet another embodiment, each transmit and receive element also includes at least one diverging lens. The transmit and receive elements and associated waveguides preferably comprise photo-patternable polymers.