Optical correlator for textile web defect detection

Cost-effective optical correlators are now available for industrial applications. One such application field is the real-time automatic inspection of textile web, in which the high data throughput of the optical correlator over-performs that of the electronic computer. Two approaches for defect enhancement using of wavelet and Wiener filters are proposed. The band-pass wavelet filter is designed to give higher weights in the frequency band, where the energy of defect is higher than that of the web, and to suppress the zero, first and all higher diffracted orders. The Wiener filters are designed based on an average defect shape, with the web texture considered as noise. Using the technique developed at INO (National Optics Institute), a set up of the Vander Lugt type correlator demonstrates experimentally the relevancy of the algorithms. Simulation and optical results are presented.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.