The present disclosure provides optical fiber preforms formed from core canes having large core-clad ratio, intermediate core-cladding assemblies, and methods for making the preforms and core cladding assemblies. The preforms are made with capped core canes. The capping material has a coefficient of thermal expansion less than the coefficient of thermal expansion of the core cane and more closely matched to or lower than the coefficient of thermal expansion of the surrounding cladding monolith in a cane-in-soot process. Presence of the cap reduces stresses that arise from differential thermal expansion of the core cane and cladding materials and leads to preforms having low defect concentration and low probability of failure during subsequent thermal processing steps.

A quartz glass container is shown and described herein. The quartz glass container exhibits a low concentration of surface defects on an inner surface of the container. In aspects hereof, the container may have a surface defect density of 50 or fewer surface defects per square centimeter within a 1 cm band centered 1 cm from the base of the container.

There is provided a method of processing an oxygen-containing workpiece. The method of processing an oxygen-containing workpiece includes controlling a fluorine concentration in the oxygen-containing workpiece based on at least one of a kind of a fluorine-containing processing gas, a processing temperature and a processing pressure used for processing the oxygen-containing workpiece.

Producing a molded body made of opaque quartz glass includes providing SiO.sub.2 grains obtained by comminuting quartz glass having a purity of at least 99.9 wt % SiO.sub.2, forming a slurry containing a suspension liquid and the SiO.sub.2 grains and which has a total solids content, wet grinding the SiO.sub.2 grains in the slurry so as to form ground SiO.sub.2 grain particles, forming a porous green body from the slurry, and sintering the porous green body. To provide a low cost quartz glass, the wet grinding of the SiO.sub.2 grains takes place at least temporarily in the presence of SiO.sub.2 nanoparticles, the proportion of which in the total solids content of the slurry is in the range of 0.1 wt % to 10 wt %, and the slurry has a solids content in the range of 76 to 80 wt % after addition of the SiO.sub.2 nanoparticles and after the wet grinding.

A silica glass crucible includes a cylindrical side wall portion, a curved bottom portion, and a corner portion that is provided between the side wall portion and the bottom portion and has a higher curvature than a curvature of the bottom portion, in which a first region provided from a crucible inner surface to a middle in a thickness direction, a second region that is provided outside the first region in the thickness direction and has a different strain distribution from the first region, and a third region that is provided outside the second region in the thickness direction and up to the crucible outer surface and has a different strain distribution from the second region, are provided, and internal residual stresses of the first region and the third region are compressive stresses, whereas an internal residual stress of the second region includes a tensile stress.

In known methods for producing a glass component, a void-containing intermediate product containing doped or non-doped SiO.sub.2 is inserted into a sheath tube composed of glass, which has a longitudinal axis and an inner bore, and is thermally treated therein. In order to subject the intermediate product to a thermal and/or reactive treatment that is reproducible and uniform in its effect from this starting point, it is proposed in one embodiment that into the sheath tube's inner bore a first gas-permeable gas diffuser is inserted which is displaceable along the sheath tube's longitudinal axis and is pressed against the intermediate product during the thermal treatment.

Methods are known for producing an anti-resonant hollow-core fiber which has a hollow core extending along a fiber longitudinal axis and an inner jacket region that surrounds the hollow core, said jacket region comprising multiple anti-resonant elements. The known methods have the steps of: providing a cladding tube that has a cladding tube inner bore and a cladding tube longitudinal axis along which a cladding tube wall extends that is delimited by an interior and an exterior; providing a number of tubular anti-resonant element preforms; arranging the anti-resonant element preforms at target positions of the interior of the cladding tube wall, thereby forming a primary preform which has a hollow core region and an inner jacket region; and further processing the primary preform in order to form a secondary preform, including a process of elongating the primary preform in order to directly form the hollow-core fiber or to form the secondary preform. The aim of the invention is to achieve a high degree of precision and an exact positioning of the anti-resonant elements in a sufficiently stable and reproducible manner on the basis of the aforementioned methods. This is achieved in that a primary preform with an outer diameter ranging from 20 to 70 mm is used for the elongation process.

One aspect relates to a process for the preparation of a quartz glass body including, providing a silicon dioxide granulate obtainable from a silicon dioxide powder, wherein the silicon dioxide granulate has a larger particle size than the silicon dioxide powder, making a 5 glass melt out of silicon dioxide granulate and making a quartz glass body out of at least part of the glass melt. The melting crucible has at least one inlet and at least one outlet. A least part of the glass melt is removed via the melting crucible outlet. One aspect further relates to a quartz glass body which is obtainable by this process. One aspect further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing 10 of the quartz glass body.

A method for producing a solid body of glass is described. The method comprises providing a polymerisable composition, curing the polymerisable composition to obtain a cured body, subjecting the cured body to thermal debinding to substantially remove the organic components in the cured body, and subjecting the cured body to sintering to obtain a solid body of silica glass. The polymerisable composition one or more at least partially organic polymerisable compound(s) which form a liquid composition at operating temperature and a solid source of silica as colloidal silica particles or silica glass micro-/nanoparticles dispersed in the liquid composition. The one or more at least partially organic polymerisable compounds comprises at least one organosilicon compound as a second source of silica that is liquid or solubilisable in the liquid composition at operating temperature to thereby increase the silica loading of the cured body prior to sintering. Compositions and methods for producing solid glass objects by additive manufacturing are also described.

One exemplary embodiment of this disclosure relates to a transfer molding assembly. The assembly includes a die having a molding cavity interconnected with a reservoir. The assembly further includes a heater operable to heat the die, and a load plate configured to move under its own weight to transfer material from the reservoir into the molding cavity.