Noncontact Measurements of Sanding and Raising Effects

Abstract

The method presented in this paper pertains to an optical roughness meter that considers a fabric in all surface directions. A previous paper presented a tribological method for investigating textile fabrics, which used a roughness meter with a contact between the probe and the surface. However, a contact is not always acceptable, and sometimes a noncontact method is better. Thus, an optical multidirectional roughness meter with the same signal processing and sample movement of the earlier apparatus has been developed. The principle is to consider the reflection of a laser beam by a fabric. The reflected ray is converted into an electrical signal with a photomultiplier, and this signal is subjected to Fourier analysis. The power spectral density versus frequency presents some peaks that reveal the basic directions of the fabric structure, the function of the weave or knit, and the fabric density. The height of these frequency peaks decreases after sanding or raising, thus characterizing the state of the fabric surface.