Optical Anisotropy in Mohair Fibers

Abstract

The diffraction from a He-Ne laser beam was used to measure the dimensional parameters, transverse sectional shape, and area of mohair fibers. Multiple-beam Fizeau fringes in transmission, and double refracting interference microscopy (Pluta polarizing interference microscope) were used to measure the refractive indices and birefringence of the mohair. The double-beam technique was applied to determine the mean re fractive indices for plane polarized light vibrating parallel and perpendicular to the fiber axis and thus the mean birefringence. Two other recent analytical methods were employed to study the optical properties of fibers from the interference patterns pro duced by the formation of multiple-beam Fizeau fringes crossing mohair fibers. These methods were used to determine Cauchy's constants and the thermal coefficient of refractive indices of the skin and core of the mohair. A comparative study of these methods is discussed and illustrated using photomicrographs.