Optoelectronic Techniques for Surface Characterization of Fabrics

In the textile field, fabric surface properties influence the tactile feel, the visual aspect and some mechanical properties. They are strongly linked to manufacturing process, particularly to surface processes. Therefore the study of these fabric surface properties proves of importance. More precisely, the tactile feel is one of the most important garment selling points since one of the first consumer actions is to touch the fabric. Thanks to objective tactile parameters, the manufacturer can design and produce fabrics which please the consumers while respecting functionality of cloth. Moreover, for standard woven or knitted structures or low grammage nonwovens, the surface state can give some information about tensile properties or strain during tensile stress. In order to characterize surface contact devices, such as tribometers1, are often used. They provide some information about friction behaviour, roughness of the surface or some other criteria more or less complex. This type of devices is often designed and used for hard materials. Concerning textile surfaces, because of their softness, these methods can have an influence on measurements in so far as superficial hairiness and even intrinsic structure may be modified. Both of these structural characteristics, hairiness and texture, are predominant in the tactile feel of textile surfaces. Complementary to tribological methods widely used but whose precision may be insufficient, non-contact methods have been developed in order to characterise fabric surface state. These methods are mainly based on optical principles and have been getting a growing interest. In this chapter we will present our contributions to the non-contact characterization of textile surfaces, firstly through the characterization of the state of surface (intrinsic structure and hairiness) and then through the evaluation of some mechanical properties of textile fabrics (strain and tensile properties). Implementations resulting in various apparatuses and some results are given in order to illustrate our purpose.