Geometrical information extraction from laser speckle pattern images using texture analysis

Abstract

In this paper, the statistical properties of speckle pattern are investigated from the point of view of computer texture analysis, and a measurement method of an object surface roughness and the object surface displacement is subsequently put forward. In the geometrical information extraction technique, the speckle pattern images are taken by a very simple configuration of setup consisting of a laser and a CCD camera. Surface roughness and displacement information is extracted based on the energy feature characterization of the grey level co-occurrence matrices of the speckle pattern images. Our experimental results show that surface roughness and displacement contained in surface speckle pattern images have a good relationship with their energy feature. By means of a set of standard surface specimens with different roughness, the relation curve is readily calibrated. Then the surface roughness of an object surface made by same material and manufactured by the same way as the standard specimens can be evaluated from a single speckle pattern image taken from the surface. Similarly, the surface displacement can also be obtained from a single speckle pattern image. The easily implemented method can be used in-process surface roughness and displacement measurement.