A system for delivering optical signals to and from an undersea optical cable may include a cable landing station connected to the undersea optical cable and configured to convey a wavelength division multiplexed optical signal from the undersea optical cable. The device subassemblies may include a multiple silhouette targets housed in a pellet trap, a dispenser, and a score counter. One or more of such coated substrates can be used for the construction of a polymerisation chamber, in which the coated sides lie within the chamber.