Process for producing an optical fibre blank and device for its use

摘要

The process consists in immersing the ends of two coaxial tubes (1, 5) made of glass and separated by a sheet of carbon (6) in a bath (2) of another molten glass and in drawing this other glass inside the inner tube (1) by creating a partial vacuum in the outer tube (5). The tubes (1, 5) which contain the liquid glass drawn in are mixed withdrawn from the bath next and are placed in the oven (9) to carry out annealing of the glass forming the tube (1) and the extracted column. After cooling, the tube (1) is separated from the auxiliary tube (5) in order to obtain a blank made up of a tubular glass sheath (1) surrounding a cylindrical glass core which has a refractive index higher than that of the sheath. This blank is softened in an oven and is drawn to obtain an optical fibre which can be employed in telecommunications and in which the surface of contact between the sheath and the core comprises very few nonuniform points at which the light transmitted by the optical fibre runs the risk of being scattered. <IMAGE>