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.

A silica glass for a radio-frequency device has an OH group concentration being less than or equal to 300 wtppm; an FQ value being higher than or equal to 90,000 GHz at a frequency of higher than or equal to 25 GHz and lower than or equal to 30 GHz; and a slope being greater than or equal to 1,000 in a case where the FQ value is approximated as a linear function of the frequency in a frequency band of higher than or equal to 20 GHz and lower than or equal to 100 GHz.

A glass is described, a glass article made of the glass as well as uses and production methods. The glass constituents are selected such that it results in excellent chemical stability and ion ex-changeability. The glass has a composition characterized by the following glass constituent phases: 0-35 mol % reedmergnerite; 10-60 mol % albite; 3.5-25 mol % orthoclase; 0-40 mol % natrosilite; 0-20 mol % parakeldyshite; 0-20 mol % narsarsukite; 0-35 mol % disodium zinc silicate; 0-35 mol % silicon dioxide; 0-30 mol % cordierite; and 0-20 mol % danburite. A quotient of a coefficient of thermal expansion of the glass multiplied by 1000 (in ppm/K) and the product of a pH value and a removal rate in alkaline environment (in mg/(dm.sup.23h)) according to ISO 695 is at least 9.25.

A glass comprising titania and silica is disclosed. A plot of average hydroxyl concentration of each segment of a plurality of segments vs. distance along the glass is provided by: y=Ax.sup.2+Bx+C, wherein A (in ppm/mm.sup.2) is in a range from about 0.0 to about 0.1, B (in ppm/mm) is in a range from about 10 to about 10, C (in ppm) is about 450 or less, y is the average hydroxyl concentration (in ppm), and x is distance (in mm) such that the hydroxyl concentration of each segment is measured using a Fourier transform infrared spectroscopy in transmission and the plot extends a distance of about 50 mm or more along the glass.

A silica glass for a radio-frequency device has an OH group concentration being less than or equal to 300 wtppm; an FQ value being higher than or equal to 90,000 GHz at a frequency of higher than or equal to 25 GHz and lower than or equal to 30 GHz; and a slope being greater than or equal to 1,000 in a case where the FQ value is approximated as a linear function of the frequency in a frequency band of higher than or equal to 20 GHz and lower than or equal to 100 GHz.

A method for loading a blank composed of fused silica with hydrogen, including loading the blank at a first temperature (T.sub.1) and a first hydrogen partial pressure (p.sub.1), and further loading the blank at a second temperature (T.sub.2) which is different from the first temperature and at a second hydrogen partial pressure (p.sub.2) which is different from the first hydrogen partial pressure. The first and second temperatures (T.sub.1, T.sub.2) are lower than a limit temperature (T.sub.L) at which a thermal formation of silane in the fused silica of the blank commences. Also disclosed are a lens element produced from such a blank and a projection lens that includes at least one such lens element.

A glass composite for use in Extreme Ultra-Violet Lithography (EUVL) is provided. The glass composite includes a first silica-titania glass section. The glass composite further includes a second doped silica-titania glass section mechanically bonded to a surface of the first silica-titania glass section, wherein the second doped silica-titania glass section has a thickness of greater than about 1.0 inch.

The present invention relates to a method of manufacturing an optical fiber preform for obtaining an optical fiber with low transmission loss. A core preform included in the optical fiber preform comprises three or more core portions, which are each produced by a rod-in-collapse method, and in which both their alkali metal element concentration and chlorine concentration are independently controlled. In two or more manufacturing steps of the manufacturing steps for each of the three or more core portions, an alkali metal element is added. As a result, the mean alkali metal element concentration in the whole core preform is controlled to 7 atomic ppm or more and 70 atomic ppm or less.

In order to reduce the degree of relaxation after an optical substrate has been compacted, in particular after a longer period, substrates (51) or reflective optical elements (50), in particular for EUV lithography, with substrates (51) of this type, are proposed. These substrates (51), which have a surface region (511) with a reflective coating (54), are characterised in that, at least near to the surface region (511), the titanium-doped quartz glass has a proportion of SiOOSi bonds of at least 1*10.sup.16/cm.sup.3 and/or a proportion of SiSi bonds of at least 1*10.sup.16/cm.sup.3 or, along a notional line (513) perpendicular to the surface region (511), over a length (517) of 500 nm or more, a hydrogen content of more than 5?10.sup.18 molecules/cm.sup.3.

A method for preparing quartz glass with low content of hydroxyl and high purity, includes providing silica powders including hydroxyl groups. The silica powders are dehydroxylated, which includes drying the silica powders at a first temperature, heating the silica powders up to a second temperature and introducing a first oxidizing gas including halogen gas, thereby obtaining first dehydroxylated powders, and heating the first dehydroxylated powders up to a third temperature and introducing a second oxidizing gas including oxygen or ozone, thereby obtaining second dehydroxylated powders. The second dehydroxylated powders are heated up to a fourth temperature to obtain a vitrified body. The vitrified body is cooled to obtain the quartz glass with low content of hydroxyl and high purity. The quartz glass prepared by the above method has low content of hydroxyl and high purity. A quartz glass with low content of hydroxyl and high purity is also provided.