Emissivity of Wavelength-Selective Radiator With Periodic Microcavities

A periodic microstructure of the cubic cavity 6.0 μm wide, 6.0 μm deep, and 6.0 μm high is built on an ultraviolet curable resin via UV nanoimprinting. The 200 nm thick gold film is sputtered on the periodic micro structure. The hemispherical spectroscopic transmittance and reflectance of the periodic microstructure with the gold film are measured using a Fourier transform infrared spectrometer with an integrating sphere. The hemispherical spectroscopic transmittance is 0.0 from 2 to 15 μm wavelength. The hemispherical spectroscopic reflectance is 1.0 from 2 to 8 μm wavelength and from 12 to 15 μm wavelength. The bottom of the hemispherical spectroscopic reflectance is 0.4 near 10 μm. Assuming Kirchhoff’s law, the maximum normal emissivity of the periodic microstructure is 0.6 near 10 μm. It is clarified that the periodic microcavities with a gold film built via UV nanoimprinting and sputtering can enhance maximum spectral emissive power of radiation.