Radiation absorbing surfaces

Claim 1

A method for absorbing radiant energy by a metal having a radiation absorbing surface said method comprising the steps: (a) preparing a metal having a substantially radiation absorbing surface by a process comprising the steps: (1) providing a substrate having on at least one surface thereof a first microstructured layer, said layer being an oxide or hydroxyoxide of a metal, selected from the group consisting of aluminum, magnesium and zinc or alloys thereof, which layer is a substantially complete conversion of a thin-film of said metal, the thickness of said thin-film prior to conversion being at least 5 nanometers and exhibiting a surface after said conversion characterized by a plurality of randomly positioned discrete protuberances of varying heights and shapes, which protuberances extend from said substrate surface a distance of not less than 20 nanometers nor more than 1500 nm, and the bases of which contact the bases of substantially all adjacent protuberances, (2) replicating said first microstructured layer by embossing, casting, or vacuum metallizing onto the surface of a second layer, said second layer being a metal, to provide said metal with a microstructured surface of randomly positioned discrete protuberances, and (3) removing said second layer from said first microstructured layer to provide said metal with a substantially radiation absorbing surface of randomly positioned discrete protuberances, and (b) orienting said radiation absorbing surface such that said microstructured surface is contacted with radiant energy so as to absorb radiant energy.

Claim 2

A method for absorbing radiant energy by a metal having a radiation absorbing surface said method comprising the steps: (a) preparing a metal having a substantially radiation absorbing surface by a process comprising the steps: (1) providing a substrate having on at least one surface thereof a first microstructured layer, said layer being an oxide or hydroxyoxide of a metal, selected from the group consisting of aluminum, magnesium and zinc or alloys thereof, which layer is a substantially complete conversion of a thin-film of said metal, the thickness of said thin-film prior to conversion being at least 5 nanometers and exhibiting a surface after said conversion characterized by a plurality of randomly positioned discrete protuberances of varying heights and shapes, which protuberances extend from said substrate surface a distance of not less than 20 nanometers nor more than 1500 nm, and the bases of which contact the bases of substantially all adjacent protuberances, (2) replicating said first microstructured layer by embossing, casting, or vacuum metallizing onto the surface of a second layer, said second layer being a metal, to provide said metal with a microstructured surface of randomly positioned discrete protuberances, and (3) removing said second layer from said first microstructured layer to provide said metal with a substantially radiation absorbing surface of randomly positioned discrete protuberances, and (b) orienting said radiation absorbing surface such that said microstructured surface is contacted with radiant energy so as to absorb radiant energy.