MRF based image stitching of electroplated diamond wire saw: For improving visual inspection accuracy of manufacturing quality

Abstract

Electroplated diamond wire saw has become the most important tool for wafer slicing in the photovoltaic field. The distribution state of abrasives on the surface of the wire saw is an important index to evaluate its manufacturing quality. However, it is difficult to inspect the abrasive distribution state along the circumferential direction on the surface of a wire saw, which is mainly limited by the acquisition of the full-cylindrical surface image of the wire saw. This work proposed a stitching method of the wire saw semi-cylindrical surface image. The unfolding model of the wire saw semi-cylindrical surface image is first established. Taking the center of gravity of the abrasives as the feature point, the matching criterion is established according to the spatial position relationship between the cameras. Based on markov random filed theory, the effective screening of feature points is realized by introducing the context information between feature points. The wire saw image is registered by the affine transformation model, and the fusion of stitching seams is realized by Laplacian image fusion algorithm. The full cylindrical surface image of an electroplated diamond wire saw can be obtained by the proposed method. Experimental results show that the time consumption of electroplated diamond wire saw image stitching is about 0.5 s, which can meet the real-time requirements of wire saw visual inspection. This work could be applied to the online inspection of the abrasive distribution state and the real-time adjustment of process parameters, which will help to improve the manufacturing quality of the electroplated diamond wire saw.