Measurement of aluminum oxide film by Fabry-Pérot interferometry and scanning electron microscopy

A novel experimental scheme for real time measurement of aluminum oxide film during anodization was developed for the first time. The scheme was established based on a combination of a fiber optic sensor of Fabry-Pérot interferometry and direct current (DC) electrochemical methods. The scheme was assembled in a way to simultaneously anodize the aluminum samples and to measure the thickness of the aluminum oxide film. The anodization process of aluminum sample was carried out in 4% sulfuric acid (H2SO4) solution by the DC methods at room temperature. The estimated thickness of the aluminum oxide film by the novel scheme was verified by scanning electron microscopy (SEM) and electrochemistry measurements. This study shows that real time measurement of the thickness of aluminum oxide film is feasible as it closely matched the thickness determined by SEM and other electrochemistry techniques.