A laterally- and longitudinally-elongated sheetform of optical material has a core and spaced broad surfaces provided with superficial light-confining measures flanking the core. At least one broad surface has an array of converging lenses, each adapted for collecting and introducing incident light rays into the core unimpeded by the superficial light-confining measures, and converging the rays onto focal points within the web. A counterpart array of reflective elements are embedded in the web at the focal points, and arranged to deflect the collected, converged rays onto transmission paths through the web generally intermediate the broad surfaces. A light-emission port provided in or by the web which is also rendered substantially free of impedance by the superficial light-confining measures. That way, collected light is generally confined between the broad surfaces, except for emissions out the emission port.