Computer Simulation of Goniophotometric Curves for Fabrics

Abstract

In preceding papers"2' the distribution curves for the specular reflection light, i.e., goniophotometric curves, were computed to simulate fabrics by using the following two fabric models.(1) The first fabric modelconsists of fine elliptic cylinders arranged side by side on the surface of an elliptic column. A parallel luminous flux perpendicular to the axes of the above elliptic cylinders is assumed to project to the surface of the fabric model. (2) The second modelj21 is assumed to consist of a number of very short elliptic columns stacked side by side with all the columns sharing a common major axis length of 2 but columns varying in short axis length. Incident light flux is assumed to be parallel to the major axes of the columns.In the preceding papers"'', the goniophotometric curves for the two fabric models were computed assuming a refractive index of 1.5. However, the refractive index of actual filaments range from 1.3 to 1.8. In the present paper in view of above calculations were made of the goniophotometric curves of above fabric models considering a range of refractive index from 1.3 to 1.8.The present computer simulation yielded the following results. (1) Fabrics made from filaments having smaller refractive index look deeper in color than fabric from filaments having comparatively larger refractive index when a parallel luminous flux is projected to the fabrics. The reason for this is because a small refractive index tends to make a larger percentage of incident light enter the fiber to make the observed color deep. (2) Fabrics more rugged in surface look deeper in color than fabrics of less rugged surface because rugged surface lets more light into the individual filaments.