Measurement of the roughness surface using the normalized autocorrelation function of the fields of the texture of speckle pattern

Abstract

We present a new method of measure of the roughness based on the analysis of the texture of speckle pattern on the surface. Images of speckle pattern over the surface are captured by means of a simple configuration using a laser, beam expander, and a camera charge coupled device (CCD). Using the properties of the normalized covariance function that we obtain from the image of the speckle through the inverse Fourier transform, we relate the values of the normalized covariance function. We compare the results obtained with the results obtained with a confocal microscope. This method can be considered as a noncontact surface profiling method and is easy to implement and can be used during the manufacturing process.