A Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and includes a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region includes a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF includes hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further includes a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below T.sub.h, wherein T.sub.h is at least about 50 C., preferably 50 C.<T.sub.h<250 C.

The present disclosure provides a method for fabrication of a glass preform. The method includes production of soot particles in a combustion chamber using a precursor material. The heating of the precursor material produces the soot particles along with one or more impurities. In addition, the method includes agglomeration of the soot particles. Further, the method includes separation of the soot particles from the one or more impurities. Also, the separation of the soot particles is performed in a cyclone separator. Furthermore, the method includes collection of the soot particles. Also, the soot particles are compacted with facilitation of a preform compaction chamber. Also, the compacted preform is sintered with facilitation of a sintering furnace. The compaction of the soot particles followed by sintering results in formation of the glass preform.

Described is a process for the refinement of a quartz powder, comprising the step of separating microparticles of refractory minerals, in particular minerals containing rare earth metal compounds, from the quartz powder by an elutriation step.

The present invention relates to a black quartz glass comprising Si of 0.5 to 10 mass %, SiO of 0.1 to 5 mass % and SiO.sub.2 of the residue, wherein the SCE reflectance at a wavelength of 350 nm to 750 nm is 10% or less; a method for producing the black quartz glass, comprising: pressure-molding a powder obtained by mixing and consolidating (1) fumed silica, or (2) a mixture powder of fumed silica and a synthetic silica powder, or (3) a mixture powder of fumed silica, spherical silica and a synthetic silica powder, with a Si powder of 0.5 to 10 mass % and a SiO powder of 0.1 to 5 mass %, and heating and sintering the pressure-molded product in the atmosphere; and a product comprising a black quartz glass member made of the black quartz glass. The present invention allows to provide a black quartz glass which has an excellent light-shielding property, has no risk of causing contamination in a step of using it, has sufficient color uniformity when the size is enlarged, and is capable of producing a large ingot, and to provide a method for producing the black quartz glass with excellent productivity even in the large ingot, and to provide a black quartz glass product made of the black quartz glass.

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.

One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, wherein the silicon dioxide granulate was made from pyrogenic silicon dioxide powder and the silicon dioxide granulate has a BET surface area in a range from 20 to 40 m.sup.2/g, making a glass melt out of silicon dioxide granulate in an oven and making a quartz glass body out of at least part of the glass melt. The oven has at least a first and a further chamber connected to one another via a passage. The temperature in the first chamber is lower than the temperature in the further chambers. On aspect relates to a quartz glass body which is obtainable by this process. One aspect relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

By means of selective laser exposure and subsequent etching away of the exposed regions (selective laser-induced etching), a cylindrical-conical cavity (15) having a mainly tangential fluid inlet (16) and axial fluid outlet (17) is formed in the quartz glass nozzle body (14) having a generally cylindrical shape.

The disclosure provides methods and systems for producing surface structures on a laser-transparent workpiece, e.g. a glass or plastic workpiece, wherein one or more USP laser pulses are focused into the laser-transparent workpiece through the workpiece surface (11), to melt a modification in the workpiece interior by heating a focus volume, wherein the pulse parameters of the at least one USP laser pulse and the depth of the laser focus in the workpiece are chosen in such a way that the topmost part of the melted modification nearly touches the workpiece surface and the workpiece surface bulges outward to form a convex surface structure by means of thermal material expansion of the melted modification.

A Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and includes a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region includes a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF includes hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further includes a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below T.sub.h, wherein T.sub.h is at least about 50 C., preferably 50 C.<T.sub.h<250 C.

A resin composition includes a base resin containing a urethane (meth)acrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator, and a silane coupling agent and hydrophobic inorganic oxide particles, wherein the content of the inorganic oxide particles is 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.