Yarn hairiness characterization using two orthogonal directions

We demonstrate that one can adequately characterize Yarn hairiness by imaging the yarn along a single projection direction using coherent optical processing. A system that simultaneously characterizes the yarn hairiness along two orthogonal projection directions was constructed. Provided that a sufficiently high number of yarn segments are sampled, a strong statistical correlation is obtained between the results in each direction. The resulting images are generated using coherent optical signal processing with a Fourier high-pass spatial filter. This filter blocks the yarn core and produces a signal that highlights the sharp transitions in the transmission of the yarn. Essentially, only the small fibres responsible for the hairiness and the yarn core contours are present. Experimental results are presented for a 62-g/km yarn possessing a high degree of hairiness. Index Terms—Electronic instrumentation, optical sensors, orthogonal directions, signal processing, yarn hairiness.Fundação para a Ciência e a Tecnologia (FCT) - BD/19028/2004