Abstract: An optical instrument for the gathering and distribution of light comprises cylindrical and a planar body formed of transparent material and optically coupled together. The cylindrical body has an elliptic and circular outer surface covered with inwardly reflecting material and a light source arranged along one focal line for the elliptic surface portion. Light gathered by the cylindrical body is transmitted to the planar body and is diffused thereby over one major surface. The instrument is advantageously applied to the illumination of passive information displays such as found in liquid crystal display timepieces where efficient energy use is extremely important.