Surface roughness measurement of aluminium thin film by laser speckle method

Abstract

In this work, laser speckle imaging technique is used to measure the surface roughness of (Grade- 6062) Aluminium sample is presented. When an optically coarse surface of Al specimen irradiated by coherent laser light, cigar like dark and bright tiny spots of images are formed. This scattering self-interference pattern is called a speckle pattern. A high resolution CCD camera records the subjective speckle pattern. The surface roughness of Al sample is determined by fractal dimension and fractal box counting technique. The conventional stylus profilometer results are matched well with this laser speckle technique.