Abstract: A method of manufacturing a preform, the method comprising rotating a primary preform about an axis X, establishing relative displacement in translation between the preform and a plasma torch, and introducing a glass powder into the plasma flame, the glass powder being accelerated prior to penetrating into the plasma flame by an accelerator gas introduced into the flow of glass powder, said process being performed in an enclosure and said introduction being performed into an atmosphere at a regulated pressure lower than the pressure outside the enclosure. Apparatus for manufacturing the preform comprises an enclosure connected to a unit for regulating the pressure inside the enclosure.

Abstract: A method of manufacturing a preform, the method comprising rotating a primary preform about an axis X, establishing relative displacement in translation between the preform and a plasma torch, and introducing a glass powder into the plasma flame, the glass powder being accelerated prior to penetrating into the plasma flame by an accelerator gas introduced into the flow of glass powder, said process being performed in an enclosure and said introduction being performed into an atmosphere at a regulated pressure lower than the pressure outside the enclosure. Apparatus for manufacturing the preform comprises an enclosure connected to a unit for regulating the pressure inside the enclosure.

Abstract: An apparatus and method for manufacturing an optical fiber preform from a tube of vitreous material. A holding device holds the tube during manufacture of the preform and a heater supplies the necessary heat energy for preform manufacturing. A diffuser is disposed adjacently to an end of the tube of vitreous material to trap and diffuse light radiation generated in the tube by the heater. The invention can be used in an apparatus for drawing an optical fiber from a preform. The diffuser traps and diffuses light radiation generated in the optical fiber preform by a fiber drawing oven.

Abstract: The invention relates to apparatus for manufacturing an optical fiber preform from a tube of vitreous material, the apparatus comprising:

Abstract: The invention relates to apparatus for manufacturing an optical fiber preform from a tube of vitreous material, the apparatus comprising:

Abstract: The invention relates to a method of treating germanium-containing gaseous waste coming from a unit for manufacturing an optical fiber preform, the method comprising the following steps:a liquid effluent is formed from the gaseous waste; andthe germanium is precipitated in the liquid effluent. According to the invention, the precipitation is performed by adding magnesium MgO to the liquid effluent.

Abstract: An installation for fabricating an optical fiber preform includes a reaction tube and an excess silica soot exhaust tube equipped internally with a screw having flat helical threads for removing the excess soot. The screw is a helix hollowed out longitudinally and the installation includes a cylinder housed within the interior passage of the helix, eccentrically disposed within this passage and bearing against the inside surface of the helix. The cylinder is rotated about its axis.