Invisible diff&rent monochromatic images are inscribed in a diffractive optical element. In some embodiments, a cable may include a first group of conductors extending along a length of the cable, a tape wrapped directly around the first plurality of conductors along the length of the cable, and a second group of conductors extending along the length of the cable, where the tape electrically isolates the first group of conductors from the second group of conductors. An appendix hereto describes bistable, bichromal, molecular colorant. The first ring has a first gap therein and the second ring has a second gap therein.