Interferometric colours produced by anodised aluminium diffraction grating

Highly ordered dimple arrays that give rise to bright structural colours with a rainbow distribution have been fabricated by means of etidronic acid anodising and subsequent selective oxide dissolution. High-purity aluminium samples were anodised at 270 V and 313 K and after removing the alumina porous film, highly ordered structures were obtained with two different cell diameters, namely 701 +/- 43 and 655 +/- 36 nm. These highly ordered near-subwavelength structures fabricated on the aluminium surface induced an optical effect for surface colorisation that could be predicted by interferometric equations. The generated angle-dependent colours were investigated. The mathematically predicted colours agree well with the reflected measured colours.