Abstract: A glass preform manufacturing method, includes: preparing a glass element having a rough surface; turning a raw material of an alkali metal compound or a raw material of an alkaline earth metal compound into particles; depositing particles of the alkali metal compound or the alkaline earth metal compound on the rough surface of the glass element; oxidizing the particles of the alkali metal compound or the alkaline earth metal compound while diffusing alkali metal oxide or alkaline earth metal oxide in the glass element; and manufacturing a glass preform into which the alkali metal oxide or the alkaline earth metal oxide is doped.

Abstract: A method for manufacturing a primary preform for optical fibers using an internal vapor deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace, supplying glass-forming gases to the interior of the tube via the supply side, creating a reaction zone with conditions such that deposition of glass will take place on the inner surface of the tube, and moving the reaction zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form one or more preform layers on the inner surface of the tube, wherein both reversal points are surrounded by the furnace.

Abstract: A method for manufacturing a primary preform for optical fibers using an internal vapor deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace set at a temperature T0, supplying doped or undoped gases via the supply side, creating a reaction zone to promote deposition, and moving the zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form at least one preform layer, which at least one layer comprises several glass layers.

Abstract: To improve a known method for making a quartz glass tube as a semifinished product for the manufacture of optical fibers, the tube comprising an inner fluorine-doped quartz glass layer and an outer quartz glass layer, so as to achieve inexpensive manufacture and improved dimensional stability of the quartz glass tube, it is suggested according to the invention that the quartz glass of the inner layer should be produced in a first plasma deposition process with formation of an inner layer having a wall thickness of at least 1.5 mm, with a fluorine content of at least 1.5% by wt. being set in the quartz glass, and that the quartz glass of the outer layer should be produced in a second plasma deposition process and deposited directly or indirectly on the inner layer with formation of a composite tube, and that the composite tube should be elongated into the quartz glass tube.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibers, wherein deposition of glass-forming compounds on the substrate takes place. The present invention furthermore relates to a method for manufacturing optical fibers, wherein one end of a solid preform is heated, after which an optical fiber is drawn from said heated end.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibers, wherein deposition of glass-forming compounds on the substrate takes place. The present invention furthermore relates to a method for manufacturing optical fibers, wherein one end of a solid preform is heated, after which an optical fibre is drawn from said heated end.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace set at a temperature T0, supplying doped or undoped gases via the supply side, creating a reaction zone to promote deposition, and moving the zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form at least one preform layer, which at least one layer comprises several glass layers.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace, supplying glass-forming gases to the interior of the tube via the supply side, creating a reaction zone with conditions such that deposition of glass will take place on the inner surface of the tube, and moving the reaction zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form one or more preform layers on the inner surface of the tube, wherein both reversal points are surrounded by the furnace.

Abstract: The present invention relates to a method of manufacturing a solid preform by moving a heat source parallel to the longitudinal axis of a substrate tube, whose inner surface is coated with one or more doped or undoped glass layers, so as to collapse the substrate tube into the solid preform in a number of passes, with an etchant being supplied to the interior of the substrate tube after a number of passes of the heat source.

Abstract: The present invention relates to a method of manufacturing an optical fibre by carrying out one or more a chemical vapour deposition reactions in a substrate tube, which method comprises the following steps:

Abstract: The reproducibility of preforms made by solution doping is significantly improved by adding an internal heat source, such as N2O, as a processing gas during the soot deposition process. The addition of the internal heat source gas results in forming a surface soot layer which exhibits a relatively uniform and consistent morphology. The improvement in the soot surface morphology results in improving the uniformity of the amount of solution dopant retained in the soot layer from preform to preform.

Abstract: A method and apparatus for making optical fiber preforms using modified chemical vapor deposition (MCVD) A starting tubular member is installed on a chemical vapor deposition apparatus and, using MCVD, a predetermined amount of selectively doped silica is deposited and consolidated on the inner surface to form an intermediate uncollapsed preform tube. At least a portion of the intermediate uncollapsed preform tube is removed from the chemical vapor deposition apparatus, installed in a collapsing apparatus and collapsed. The collapsing uses an oxy-hydrogen burner or a plasma torch. Optionally, additional deposition is performed during the collapsing operation. A stretching may be performed concurrent with the collapsing.

Abstract: A method and apparatus for providing a uniform coating thickness along an axial direction within an internal portion of a substrate tube is disclosed. A gas delivery unit is configured to coat the internal portion of the substrate tube. The gas delivery unit includes an insert. At least one of an inner diameter of the insert, a length of the insert, a gap between the insert and the substrate tube, and a flow of the gas mixture delivered to the substrate tube is configured to provide the uniform coating thickness along the axial direction.

Abstract: A method and apparatus for forming a glass article such as an optical fiber having a substantially matching viscosity across an interface associated with a first section and a second section of the optical fiber is disclosed herein. The first section has a first halogen concentration and the second section has a second halogen concentration. At least one of a partial pressure of the second halogen provided to a substrate tube and a temperature of the substrate tube is configured to affect the concentration of the second halogen in the second section. Optical fiber embodiments are also included.

Abstract: A pressure monitoring system for use in monitoring gas pressure within a rotating tube has a chemical delivery tube which projects into the rotating tube and whose distal end is sealed to the interior wall of the tube. A coaxial tube surrounds the delivery tube and forms a passageway between the two tubes which is in communication with the rotating tube interior through the seal mounting means. The gas pressure within the passageway is an indication of the pressure within the rotating tube, and is measured within a pressure monitoring unit which can control the pressure through the gas supply or through a low pressure device. In a second embodiment of the invention, a buffer gas supply coupling member is mounted to the coaxial tube and sealed to the exterior of the rotating tube to create a buffer zone. In a third embodiment of the invention, the buffer zone arrangement is modified to produce a more complete flow of buffer gases within the buffer zone.

Abstract: The object of the invention is to provide an apparatus for manufacturing a porous glass preform, which comprises a reaction vessel in which local stress concentration caused by expansion due to heat is prevented, and there is no fear of the occurrence of deformation or cracks. The apparatus of this invention manufactures the porous glass preform by depositing glass particles blown from a burner on the seed rod rotating around its axis, and this apparatus is characterized in that the reaction vessel is provided with a means for relieving concentration of stress due to thermal expansion of the reaction vessel.

Abstract: The specification describes a process and apparatus for collapsing preform tubes in Modified Chemical Vapor Deposition processes. The problem of bubble formation during tube collapse was found to be attributable to excess dopant vapor pressure emitted from the hot zone during the final stage of tube collapse. This excess pressure is controlled by cooling the tube in advance of the torch, thereby decreasing the viscosity of the dopant vapor and increasing its transport rate. This is found to reduce internal tube pressure and eliminate bubble formation in the collapsed preform.

Abstract: Applicants have determined that much of the nonuniformity in solution doped preforms is due to nonuniformity of the soot layer caused by the high temperature necessary for complete reaction, and that MCVD fabrication using reaction temperature lowering gases such as nitrous oxide (N.sub.2 O) can produce more uniform soot layers. The conventional oxygen/reactant gas mixture presents a very small temperature window in which a uniform silica soot layer can be deposited without sintering. If the temperature in oxygen is too low, SiCl.sub.4 will not react completely and silicon oxychlorides will form. This degrades the soot layer and makes it unusable. If the temperature is too high the soot layer begins to sinter, decreasing the surface area and porosity. Adding a reaction temperature lowering gas lowers the reaction temperature and enables deposition of soot on the tube wall at a temperature substantially lower than the sintering temperature.

Abstract: A large optical preform 303 is made by a modified chemical vapor deposition (MCVD) process by depositing successive layers of core and cladding materials onto the inside surface of a rotating glass tube 33 having a hydroxyl ion (OH.sup.-) level that is less than 0.5 parts per million (ppm) by weight. The tube is then collapsed inwardly to form a core rod 301 in which the deposited core material 31 has a diameter that is greater than about 5 millimeters and the deposited cladding material 32 has an outside diameter that is less than about 15 millimeters. A machine-vision system 140, 150, 160 monitors and controls the diameter of the glass tube by regulating the pressure within the tube. Moreover, the machine-vision system monitors and controls the straightness of the tube by varying its rotational speed according to angular position. After the core rod 301 is formed, it is plasma etched to remove contaminants, and then overclad with two glass jackets 34, 35 having a hydroxyl ion (OH.sup.

Abstract: A process of fabricating an optical fiber preform, preferably a multimode optical fiber preform, having a maximum refractive index along an axis of the fiber and a lower refractive index at its periphery. The process includes the following steps: depositing successive layers onto the interior of the tube with the refractive index increasing from the first, larger diameter layer to the central layer, each layer being formed from gases which react with each other inside the tube, and varying the proportions of the gases from one layer to another to vary the index. The gases are introduced into the tube at a velocity such that the radial index profile is homogenized in the longitudinal direction. This velocity is advantageously maintained substantially the same for the fabrication of all the layers. This process produces preforms having a homogeneous index profile in the longitudinal direction.