Thomson-Csf

Alcatel Fibres Optiques

Lignes Telegraphiques Et Telephoniques

Michel Faure

Yves Lumineau

Marc Turpin

Jacques Dubos

Bernard Floch

Arnaud De Panafieu

Christiane Baylac

David Sullerot

Yves Nemaud

Apparatus for detecting irregularities in the diameter of a filament has a small light source placed at the focus of an objective lens system. A horizontal slot constitutes a diaphragm for the objective lens system. A first optical system forms an image of the slot in a plane in which the filament runs past. Detectors detect the beam intercepted by the filament. An optical splitting system (P1) is interposed in the path of the beam (A), downstream of the slot (3) and upstream of the filament (5). The system is designed to form two sharp images (3', 3') of the slot (3) in a plane (4). The detectors are two oppositely-connected detectors (D1, D2) each receiving a respective beam (C, C') intercepted by the filament (5).

Apparatus for detecting irregularities in the diameter of a filament

Highly accurate centering of an optical fiber within a primary cladding deposited by a coating device is carried out by automatic regulation during the fiber-drawing process in order to optimize the mechanical properties of the fiber. The position of the coating device is controlled in dependence on the position of the fiber with respect to an origin of coordinates (O) determined by optoelectronic means. The frusto-conical lower end of the coating die is maintained at each instant by electronic and electromechanical means at the point (O') located at this level on the straight-line segment (OR) which joins the origin to the first point of contact of the fiber with the pulley used for guiding the fiber towards a storage drum.

Method for automatic centering of an optical fiber within a primary

In the drawing of an optical fibre from a glass preform or gathering mould maintained at an appropriate temperature, a process and a system is described for controlling and regulating the characteristics of the optical fibre. To this purpose the fibre formation temperature within the drawing furnace is controlled by a measurement of the tensile stress. The heating of the furnace is regulated, while maintaining constant the tensile stress on the glass fibre at the fibre formation point. A gauge with an electronic measuring bridge is used to carry out a measurement at the preform suspension point, while correcting the effect of the weight reduction of the preform during drawing.

Process and apparatus for controlling the drawing of an optical fibre

A process for the manufacture of a glass blank in the form of a rod from which the optical fibre is drawn, said blank being produced starting from a molten bath of glass. A first stage of the process comprises melting a mixture of starting materials having a higher impurity content (&lt;10.sup.-4) in the form of so-called transition metals then the final blank (&lt;10.sup.-7). A second stage consists in inducing separation into two solid phases (a hard phase rich in silica and a soft phase poor in silica) by drawing the blank from the bath of molten glass and by subsequently subjecting it to a thermal annealing treatment. This is followed by deep etching and by peripheral etching to eliminate the soft phase and its impurities to different extents as a function of depth, which creates a radial refractive index gradient and an optical cladding.

Process for the production of graded index optical fibres

Growing community of inventors

Paris, France

Michel Faure