In this work we use an experimental setup implemented in the Optical Physics Laboratory of PUCP, in order to study and to measure the roughness of surfaces with different surface finishing as milling, turning, etc. The measurement method is based on a two-dimensional scan of scattered light like from rough metal surface when the surface is illuminated by laser light. The light is scattered likes speckle in all space and arrives onto the CCD of a digital camera. The speckle images of rough surfaces are captured at different angles of illumination. We have analyzed the dependence between the structure of speckle and the surface roughness. Using two-dimensional Fast Fouríer Transform it has been possible to compute the correlation between speckle pattern images and find out the relationship between surface roughness and speckle patterns decorrelation for different metal surface finishing.