| http://www.w3.org/ns/prov#value | - As shown in FIG. 3 and 4, concavity and convexity 8 representing interference fringes of hologram are formed on the rear surface of the front board 2 in the hologram portion building area 6 and moreover the surface of the concavity and convexity is covered with a reflective metallic film 11a made of metallic material such as Al, Au, Ag, Cu, Ni, Te, Bi or the like.
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