A method of forming an imaging fibre apparatus comprises: •arranging core rods 102 and cladding rods 104 to form at least one primary stack 100a, each primary stack 100a comprising a plurality of core rods 102 and cladding rods 104 arranged in a stack arrangement thereby to form a plurality of core regions within a cladding region; •performing a drawing process to form a plurality of drawn stacks from the at least one primary stack; •wherein the plurality of core rods and cladding rods are further arranged to have a selected shape such that the plurality of stacks stack together in a desired arrangement and wherein the stack arrangement comprises an at least partial outer layer of cladding rods thereby to provide separation between core regions of respective adjacent stacks when stacked in the desired arrangement, the method further comprising: •stacking the plurality of drawn stacks together in the desired arrangement to form a further stack; •drawing the further stack; and •using the drawn further stack to form an imaging fibre apparatus.

Known heating burners for producing a welded joint between components of quartz glass include a burner head in which at least one burner nozzle is formed, a burner-head cooling system for the temperature control of the burner head and a supply line connected to the burner nozzle for a fuel gas. Starting from this, to modify a heating burner in such a way that impurities in the weld seam between quartz-glass components to be connected are largely avoided, it is suggested that the burner head should include a base body of silver or of a silver-based alloy.

Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a flat bottom portion, wherein the primary rod comprises a core rod surrounded by at least one outer cladding layer; and a cylindrical sacrificial tip having a first end attached to the flat bottom portion of the primary rod, a second end opposite the first end, and a hollow interior region extending fully from the first end to the second end, wherein the sacrificial tip is circular in cross section and the first end of the sacrificial tip has a constant inside diameter and outside diameter along its entire length from the first end to the second end, and wherein the constant outside diameter is equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e. tipped) preform for subsequent fiber draw. Material waste as well as the drip time is reduced and the cladding-to-core ratio, crucial for waveguide properties, is maintained for the whole preform compared to a square cut preform without the sacrificial tip.

Known heating burners for producing a welded joint between components of quartz glass include a burner head in which at least one burner nozzle is formed, a burner-head cooling system for the temperature control of the burner head and a supply line connected to the burner nozzle for a fuel gas. Starting from this, to modify a heating burner in such a way that impurities in the weld seam between quartz-glass components to be connected are largely avoided, it is suggested that the burner head should include a base body of silver or of a silver-based alloy.

A method of production of a frac plug is disclosed comprising providing a blank defining an interior of the frac plug, placing a glass material around the blank such that a fiber reinforcement within the glass material is off axis to a longitudinal axis of the frac plug and wherein the placing forms a glass material blank, removing the blank from the glass material blank and performing at least one mechanical processing of an exterior of the glass material blank.

A method for manufacturing an optical fiber preform including a core part and a cladding part is disclosed. The method includes: adding an alkali metal to an inner surface of a silica-based glass pipe; etching the inner surface of the silica-based glass pipe to which the alkali metal is added; making a glass rod by collapsing the silica-based glass pipe after the etching; and making an optical fiber preform using the glass rod. The silica-based glass pipe is heated in the adding such that a surface temperature of the silica-based glass pipe falls within a temperature range of 1500 C. or higher to lower than 2000 C.

The present invention provides a method for manufacturing an optical fiber base material and an optical fiber base material, the method including: arranging a rod containing SiO.sub.2 family glass for core, in a container; pouring a SiO.sub.2 glass raw material solution for cladding layer and a hardener into the container, the glass raw material solution containing a hardening resin; solidifying the glass raw material solution through a self-hardening reaction; and then drying the solidified material and heating the solidified material in chlorine gas, to manufacture an optical fiber base material in which a SiO.sub.2 cladding layer is formed in an outer periphery of the rod containing SiO.sub.2 family glass for core.

A method of forming an imaging fibre apparatus comprises arranging rods to form a plurality of stacks each comprising a respective plurality of rods, wherein: for each stack, the respective plurality of rods comprises rods having different core sizes, the rods of different core sizes being arranged in a selected arrangement, and the rods of different core sizes being arranged such that each stack has a respective selected shape; wherein the selected shape or shapes are such that the stacks stack together in a desired arrangement; the method further comprising: drawing each of the plurality of stacks; stacking together the plurality of drawn stacks together in the desired arrangement to form a further stack;drawing the further stack; and using the drawn further stack to form an imaging fibre apparatus, wherein the selected arrangement of the rods in each stack and the selected shape or shapes of the stacks are such that the further stack comprises a repeating pattern of rods of different core sizes.

An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and an inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

A preparation method for a low oxygen content semiconductor core composite material optical fibre preform comprise: (1) in a nitrogen gas atmosphere glovebox, tightly packing semiconductor core raw material powder into a central hole of a cladding glass tube which is sealed at one end; and (2) performing vacuum pumping on the cladding glass tube packed with the semiconductor core raw material powder, and simultaneously sealing another end of the hot-drawn glass tube to vacuum sealing the semiconductor core raw material powder within the cladding glass tube, so as to obtain the low oxygen content semiconductor core composite material optical fibre preform. The method solves problems in the traditional optical fibre preform preparation methods such as poor packing tightness, high oxygen content in drawn fibre cores, and poor transmission performance in prepared optical fibres.