CPC H01Q 17/002 (2013.01) [C09D 5/004 (2013.01); C09D 5/32 (2013.01); C22C 19/058 (2013.01); H01Q 15/142 (2013.01); H01Q 15/145 (2013.01); Y10T 428/12014 (2015.01); Y10T 428/24917 (2015.01)] | 20 Claims |
1. A multilayer thin film that reflects an omnidirectional structural color comprising:
a reflective core layer comprising a metallic material;
a second layer extending across the reflective core layer, wherein the second layer is a dielectric absorber or dielectric material;
a third layer extending across the second layer, wherein the third layer comprises a semi-transparent absorbing layer; and
an outer layer extending across the third layer, wherein the outer layer is formed from a dielectric material or a colorful dielectric material, wherein
the multilayer thin film reflects a single narrow band of visible light that is less than 30° measured in Lab color space when the multilayer thin film is exposed to broadband electromagnetic radiation and viewed from angles between 0° and 45° relative to a direction normal to an outer surface of the multilayer thin film, and
the reflective core layer has a skin depth δ of greater than or equal to 1.0 μm in a frequency range from 20-40 GHz, as calculated by:
wherein
δ is skin depth in meters (m); ρ is resistivity in ohm meter (Ω·m); f is frequency of an electromagnetic radiation in hertz (Hz); μ0 is permeability; and μr is relative permeability of the metallic material.
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