Thermal radiation control structure obtained by anisotropic anode etching of Al

By anodically etching a (100)-oriented Al foil with an etching mask in hydrochloric acid solution, an ideally ordered array of Al holes was obtained. The Al hole array structure showed wavelength selective thermal radiation property. Wavelength band of the thermal radiation could be tuned by controlling the aperture size of the hole. The aperture size of the Al hole was controlled by optimizing geometrical structures of the etching mask and anode etching conditions.