An ink set for an image recording apparatus, includes a first ink, and a second ink which has the same color base as that of the first ink but is different from the first ink in density. In a constructed embodiment the composite structure is formed from a block of thermally conductive graphite in which a plurality of cylindrical holes are formed which are filled with acoustic dampening material. The opposing spaced apart optical fiber end faces are self-aligned because the pair of optical fiber end portions are formed from a single fiber which has been directly secured to the substrate. Clusters are formed, by a processor, as a function of the radar data.