On the theory of the process of forming of preforms for drawing double-layer glass fibres with the prescribed configuration of the core cross section

In Ref. 1 a method has been proposed for obtaining double-layer light guides (glass fibres) with a noncircular core. This method is based on the use of surface tension forces. For this purpose use is made of a double-layer glass preform with a core of the circular cross section and with a coat having the external boundary in the shape of a circumference. The boundary of the core and the coat, as well as the external boundary of the preform, are represented in Fig. 1 by solid lines: 1 is the material of the core and 2 is the material of the coat. Part of the coat is removed along the generatrix, as is shown, for example, in Fig. 1 by the dot-dash line.