24—AN ANALYSTS OF FIZEAU FRINGES CROSSING A FIBRE WITH A MULTIPLE SKIN

Abstract
A mathematical formula is derived for the shape of multiple-beam Fizeau fringes crossing a cylindrical fibre having a core surrounded by a double skin. A general formula is also deduced for the case of a multiple skin. An an experimental illustration, the formula is applied to calculation of the refractive indices along the multiple skin of a natural fibre from the shape of the fringe shift.