Surface Defect Detection for Some Ghanaian Textile Fabrics using Moire Interferometry

Abstract

This analysis focused on using Moire Interferometry method to measure surface defects in woven fabrics. A laser imaging system based on moire Interferometry has been used as a tool for surface defect inspection of static textile fabric. Test textile fabrics samples with five different types of defects (hole, oil stains, warp-lacking, weft-lacking and dirt) were used. With the sample sand witched between two Ronchi rulings and illuminated by an expanded HeNe laser beam to form Moire configuration. The images from the fabric were acquired with a high resolution CCD camera. The recorded images were transferred to a computer for analysis by the image pro plus 5.0 software. By making use of image processing and FFT techniques, the surface defects such as lack of yarns and oil stains were analysed and detected. During the process of inspection and defect identification, it was observed that the three parameters, textual structure, the shape and size of the defect varied. In this paper, moire based technique for defect detection is presented. The result of the inspection of the textile fabric on the textile images revealed that FFT analysis serves as a filter in identifying such defects. Also, the fabric texture densities limited the intensity of the laser beam transmission through some fabrics. However, the variation of such intensities helped to deduce that the area covered with stain scatter most of the incident light and the more localised the defect the more the spread out of its transform. It explained the behaviour of the frequency spectrum of each sample and the smaller the width of the yarn spacing, the broader the entire diffraction pattern.