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.

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 a inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

This technology is directed to the preparation of doped-bismuth-silicate seed crystals through controlled crystallization (e.g. dimensionality of growth and nucleation mechanism) and the method of forming high purity single seed (particle size ranges from micrometers to millimeters) for various uses. These seed crystals have a nominal stoichiometry of Bi.sub.2-xA.sub.xSiO.sub.5, Bi.sub.2-xA.sub.xSi.sub.3O.sub.9, Bi.sub.4-xA.sub.xSi.sub.3O.sub.9, and Bi.sub.12-xA.sub.xSiO.sub.20, where A is a rare earth dopant selected from La, Ce, Nd, Pr, and/or Sm.

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.

Provided is a silica glass member which exhibits high optical transparency to vacuum ultraviolet light and has a low thermal expansion coefficient of 4.010.sup.7/K or less at near room temperature, particularly a silica glass member which is suitable as a photomask substrate to be used in a double patterning exposure process using an ArF excimer laser (193 nm) as a light source. The silica glass member is used in a photolithography process using a vacuum ultraviolet light source, in which the fluorine concentration is 1 wt % or more and 5 wt % or less, and the thermal expansion coefficient at from 20 C. to 50 C. is 4.010.sup.7/K or less.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt out of the silicon dioxide granulate and iii) Making a quartz glass body out of at least part of the glass melt, wherein the provision comprises the steps I. Providing a silicon dioxide powder with at least two particles made from a silicon-chlorine compound, II. Bringing the silicon dioxide powder into contact with steam to obtain a treated silicon dioxide powder and III. Granulating the treated silicon dioxide powder to obtain a silicon dioxide granulate, and wherein the chorine content of the silicon dioxide powder is greater than the chlorine content of the silicon dioxide granulate. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a process for providing a silicon dioxide granulate. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

A diffuser material of synthetically produced, pore-containing quartz glass and a method for the manufacture of a molded body consisting fully or in part thereof. The diffuser material has a chemical purity of at least 99.9% SiO.sub.2, a cristobalite content of not more than 1%, and a density in the range of 2.0 to 2.18 g/cm.sup.3. Starting therefrom, to indicate a diffuser material which is improved with respect to diffuse reflectivity with Lambertian behavior over a wide wavelength range, high material homogeneity and UV radiation resistance, the quartz glass has a hydroxyl group content in the range of at least 200 wt. ppm and at least 80% of the pores have a maximum pore dimension of less than 20 m.

One aspect relates to a process for the preparation of a quartz glass body, including provision of a silicon dioxide granulate, making a glass melt from the silicon dioxide granulate and making a quartz glass body from at least part of the glass melt. The provision includes making a silicon dioxide powder with at least two particles prepared from a silicon-chlorine compound, bringing the silicon dioxide powder into contact with ammonia to obtain a treated silicon dioxide powder, and granulating the treated silicon dioxide powder to obtain a silicon dioxide granulate. The chlorine content of the silicon dioxide powder is greater than the chlorine content of the silicon dioxide granulate. One aspect relates further to a quartz glass body which is obtainable by this process. One aspect also relates to a process for the preparation of a silicon dioxide granulate.

A method of forming a doped silica-titania glass is provided. The method includes blending batch materials comprising silica, titania, and at least one dopant. The method also includes heating the batch materials to form a glass melt. The method further includes consolidating the glass melt to form a glass article, and annealing the glass article.

A doped silica-titania (DST) glass article that includes a glass article having a glass composition comprising a silica-titania base glass containing titania at 7 to 14 wt. % and a balance of silica, and a dopant selected from the group consisting of (a) F at 0.7 to 1.5 wt. %, (b) B.sub.2O.sub.3 at 1.5 to 5 wt. %, (c) OH at 1000 to 3000 ppm, and (d) B.sub.2O.sub.3 at 0.5 to 2.5 wt. % and OH at 100 to 1400 ppm. The glass article has an expansivity slope of less than about 1.3 ppb/K.sup.2 at 20? C. For DST glass articles doped with F or B.sub.2O.sub.3, the OH level can be held to less than 10 ppm, or less than 100 ppm, respectively. In many aspects, the DST glass articles are substantially free of titania in crystalline form.