A light-based touch-sensitive surface, including a housing, a surface attached to the housing for receiving touch input, a plurality of light sources in the housing for emitting light that crosses the surface, a plurality of light receivers in the housing for detecting the light emitted by the light sources, a curved lens adjacent to the surface through which the light emitted by the light sources passes, including two substantially similarly curved exterior panels, one of which forms a curved rim for the surface, and a calculating unit in said housing, connected to the light receivers, for calculating a touch location based on an absence of light expected to be received by the receivers.