Redrawable glass, light guide element having said glass, and uses thereof

Abstract

To provide a redrawable highly transparent glass for light guide elements, for example for glass fibres, a method for producing the glass, and uses of the glass.SOLUTION: Provided is a glass comprising SiO2 and at least one of two components Gd2O3 and Y2O3, a ratio of a sum of the proportions by weight of Gd2O3 and Y2O3 to the proportion by weight of SiO2 being at least 0.01, wherein a proportion of Ta2O5 is at most 10 wt.%, wherein a proportion of ZrO2 is at least 0.1 wt.%, preferably 0.1-10 wt.%, wherein a ratio of the proportion by weight of B2O3 to the proportion by weight of SiO2 is at most 0.50.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a redrawable glass, in particular for glass fibers, to an optical waveguide element comprising said glass, and to the use of said glass and / or said optical waveguide element. In particular, the present invention relates to a highly transparent glass, to a method for producing said glass, and to the use of said glass. The glass of the present invention is preferably used as a core glass in a light guide and / or image guide. The present invention also relates to a light guide and / or image guide comprising a glass according to the present invention as a core glass and a cladding glass. The present invention further relates to the use of said glass in the fields of imaging, projection, communications, optical messaging technology, mobile drives, laser technology, and disinfection, as well as optical elements or preforms (so-called "preforms") of said optical elements.

[0002] Technical background Optical fiber light guides are becoming increasingly common in various technical and medical fields, such as general industrial engineering, lighting and traffic technology, the automotive industry, medical technology, such as dentistry or endoscopy. Due to their good heat and chemical resistance, glass optical fiber light guides are typically used, consisting of individual fibers organized into fiber bundles. The individual optical fiber guide fibers guide light by total internal reflection. The most widespread optical fiber guide fibers are step-index fibers, which consist of a core made of a core glass, which has a constant refractive index across its cross section. The core glass is surrounded by a cladding made of a cladding glass with a lower refractive index. Total internal reflection occurs at the interface between the core glass and the cladding glass.

[0003] The amount of light that can be input into such a fiber is proportional to the numerical aperture (NA) of the fiber and the square of the cross-sectional area of ​​the fiber core. The NA corresponds to the sine of the angular area over which light can be coupled into the fiber, also referred to as the opening angle.

[0004] In addition to the numerical aperture, the attenuation of light within the fiber also plays a major role. Therefore, only core glasses with low attenuation can be used. The raw materials used to melt these core glasses are quite expensive due to their high purity, which can significantly increase the manufacturing costs of these fibers or light guides and / or image guides made from these fibers. Furthermore, it is desirable to no longer use toxic components such as PbO, CdO, As2O3, BeO, HgO, Tl2O, and ThO2 for environmental reasons.

[0005] Especially for mobile applications, the reliability of the fiber is important, i.e., its resistance to aging under temperature fluctuations from approximately -50°C to 110°C, its resistance to mechanical loads, especially vibrations, and its chemical resistance to environmental influences and cleaning procedures. In this case, the weather resistance and resistance of the core to alkaline solutions are particularly important. The fiber density is also important, as it has a direct impact on the payload and fuel consumption of aircraft or automobiles. The density of step-index fiber is primarily determined by the density of the core glass.

[0006] The production of optical step fibers from multicomponent glasses is carried out using the so-called double crucible method or the rod-in-tube method. In both cases, the core glass and cladding glass are mixed in a 10 5 ~10 6The fiber is then drawn to a temperature corresponding to the viscosity range of 1000 dPa·s. To produce a stable fiber with low attenuation, the core and cladding glasses must be compatible with each other in a range of properties, such as viscosity, thermal expansion, and crystallization tendency. On the other hand, they must have high purity, as guaranteed by pure raw materials and, above all, by the manufacturing method, as mentioned above. In particular, the interface between the fiber core and the cladding must be free of reactions between the core and cladding glasses, such as diffusion or crystallization, which would disrupt the total internal reflection of the light guided within the fiber core and thereby increase attenuation. Furthermore, crystallization would also impair the mechanical strength of the fiber.

[0007] Against this background, WO 2013 / 104748 describes highly transparent glasses that can be used as core glasses in optical waveguides. This document focuses particularly on low attenuation in the near-infrared range. In particular, low attenuation is achieved at a wavelength of 1050 nm.

[0008] However, high transmittance (low attenuation) at lower wavelengths is also becoming increasingly important for various applications. For example, in a process known as beam curing, UV-A radiation is used, among other things, to cure materials such as paints, printing inks, or adhesives. In addition to surface curing, there is also so-called point curing, in which the curing radiation is selectively directed to the desired point of action without exposing other parts of the product to radiation. UV point curing is used, for example, in the manufacture of cardiac catheters or oxygen generators to form adhesive joints between different materials. High transmittance at lower wavelengths also plays an important role in disinfection or sterilization, for example, using UV radiation.

[0009] Therefore, there is a need for suitable glasses, especially for light guide and / or image guide applications.

[0010] Optical waveguide elements are also referred to herein as optical waveguides for short. Such optical waveguides are often also called light guide fibers and may be abbreviated accordingly as "LLF", and image guides may also be abbreviated as "BL" (German) or "IG" (English: image guide). For specific image guides, the abbreviation "LFB" (from English: "Leached Fiber Bundle") is often also used.

[0011] In this case, the image guide optionally has a plurality of optical waveguides or optical waveguide fibers aligned and arranged so that an image on its input side can be transmitted substantially unimpeded to its output side, and in this connection one-to-one alignment or arrangement of optical waveguide fibers of or within an image guide is often also spoken of.

[0012] Disclosure Overview In a first aspect, the present invention relates to a glass comprising SiO2 and at least one of the two components Gd2O3 and Y2O3, in which the ratio of the sum of the weight proportions of Gd2O3 and Y2O3 to the weight proportion of SiO2 is at least 0.01, the proportion of Ta2O5 is at most 10% by weight, the proportion of ZrO2 is at least 0.1% by weight, and the ratio of the weight proportion of B2O3 to the weight proportion of SiO2 is at most 0.50.

[0013] Advantageously, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm.

[0014] In a third aspect, the present invention relates to a glass article or in particular an optical waveguide element, in particular a glass fiber, comprising or consisting of a glass (in particular the glass of the invention) comprising SiO2 and at least one of the two components Gd2O3 and Y2O3, in which the ratio of the sum of the weight proportions of Gd2O3 and Y2O3 to the weight proportion of SiO2 is at least 0.01, the proportion of Ta2O5 is at most 10% by weight, the proportion of ZrO2 is at most 0.1% by weight and the ratio of the weight proportion of B2O3 to the weight proportion of SiO2 is at most 0.50.

[0015] In a fourth aspect, the present invention relates to a method for producing a glass (in particular the glass of the invention) comprising SiO and at least one of the two components GdO and YO, in which the ratio of the sum of the weight proportions of GdO and YO to the weight proportion of SiO is at least 0.01, the proportion of TaO is at most 10% by weight, the proportion of ZrO is at least 0.1% by weight, and the ratio of the weight proportion of BO to the weight proportion of SiO is at most 0.50, wherein the method comprises the following steps: - melting the glass frit, - cooling the glass obtained, in particular to obtain the glass of the invention. The present invention relates to a method, including:

[0016] In a fifth aspect, the present invention provides a method for producing a glass article (in particular an optical waveguide element) comprising SiO2 and at least one of the two components Gd2O3 and Y2O3, in which the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the proportion of Ta2O5 is at most 10% by weight, the proportion of ZrO2 is at least 0.1% by weight, and the ratio of the weight percentage of B2O3 to the weight percentage of SiO2 is at most 0.50, said method comprising the following steps: - melting the glass frit, - cooling the glass obtained, in particular to obtain a glass article, in particular an optical waveguide element according to the invention. The present invention relates to a method, including:

[0017] In a sixth aspect, the present invention relates to the use of a glass (especially a glass of the invention) as a fiber glass, in particular as a core glass in a light guide and / or image guide, in which the glass comprises SiO2 and at least one of the two components Gd2O3 and Y2O3, and the ratio of the sum of the weight proportions of Gd2O3 and Y2O3 to the weight proportion of SiO2 is at least 0.01, the proportion of Ta2O5 is at most 10% by weight, the proportion of ZrO2 is at least 0.1% by weight, and the ratio of the weight proportion of B2O3 to the weight proportion of SiO2 is at most 0.50.

[0018] In a seventh aspect, the present invention relates to the use of a glass article (in particular a glass of the invention) as fiber glass, in particular as core glass in light guides and / or image guides, wherein the glass article comprises SiO2 and at least one of the two components Gd2O3 and Y2O3, and wherein the ratio of the sum of the weight proportions of Gd2O3 and Y2O3 to the weight proportion of SiO2 is at least 0.01, the proportion of Ta2O5 is at most 10 wt.-%, the proportion of ZrO2 is at least 0.1 wt.-% and the ratio of the weight proportion of B2O3 to the weight proportion of SiO2 is at most 0.50.

[0019] In an eighth aspect, the invention relates to the use of an optical waveguide element according to the invention in endoscopic applications, in particular in endoscopes, advantageously single-use endoscopes, in projection devices, in optical messaging technology, in automotive applications, in laser technology and disinfection, wherein the optical waveguide element comprises, in particular as core glass, a glass comprising SiO and at least one of the two components GdO and YO, wherein the ratio of the sum of the weight proportions of GdO and YO to the weight proportion of SiO is at least 0.01, the proportion of TaO is at most 10 wt.-%, the proportion of ZrO is at least 0.1 wt.-% and the ratio of the weight proportion of BO to the weight proportion of SiO is at most 0.50.

[0020] Glasses with a proportion of Y2O3 and Gd2O3 of at least 0.1% by weight each, particularly preferably at least 0.2% by weight each, are preferred. This improves meltability. Further advantages, such as suppression of crystallite formation, are also mentioned here.

[0021] Further configurations of the aspects of the invention can be made in particular on the basis of the embodiments described herein, each of which is relevant to all aspects of the invention and which can in particular also be combined with one another.

[0022] Detailed Description of Disclosure The present invention relates to a redrawable glass, in particular for glass fibers. The invention also relates to a method for producing said glass and to the use of said glass. The glasses of the present invention are preferably used as core glasses in light guides and / or image guides. Furthermore, the present invention relates to optical wave guide elements, in particular light guides and / or image guides, comprising a glass according to the present invention as core glass and a cladding glass.

[0023] Glass Composition The compositions of the glasses according to the invention are given herein in weight percent [wt. %], unless otherwise specified. The indications relate to analytical compositions, unless otherwise specified. Those skilled in the art know how the composition of glasses can be analyzed. This analysis can be carried out in particular using X-ray fluorescence spectroscopy (English: "X-ray Fluorescence Spectroscopy", XRF). This is explicitly stated wherever synthetic compositions are referenced in the present disclosure.

[0024] In some embodiments, the SiO2 content is in the range of 10-55 wt%, e.g., 15-45 wt%, 17-40 wt%, 18-35 wt%, 20-35 wt%, 22-35 wt%, 23-34 wt%, 24-33 wt%, 24-32 wt%, 25-32 wt%, or 27-31 wt%. In some embodiments, the SiO2 content is at least 10 wt%, e.g., at least 15 wt%, at least 17 wt%, at least 18 wt%, at least 20 wt%, at least 22 wt%, at least 23 wt%, at least 24 wt%, at least 25 wt%, or at least 27 wt%. In some embodiments, the SiO2 content is at most 55 wt%, at most 45 wt%, at most 40 wt%, at most 35 wt%, at most 34 wt%, at most 33 wt%, at most 32 wt%, or at most 31 wt%.

[0025] In some embodiments, the percentage of Gd2O3 is in the range of 0-15 wt%, e.g., 0-10 wt%, 0-9.0 wt%, 0-8.0 wt%, 0.1-7.0 wt%, 0.2-7.0 wt%, 0.5-7.0 wt%, 1.0-7.0 wt%, 1.5-6.0 wt%, 2.0-5.5 wt%, 2.5-5.0 wt%, 3.0-5.5 wt%, 3.0-4.5 wt%, or 3.5-4.0 wt%. In some embodiments, the percentage of Gd2O3 is at least 0.1 wt%, at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, or at least 3.5 wt%. In some embodiments, the percentage of Gd2O3 is at most 15 wt%, e.g., at most 10 wt%, at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 6.0 wt%, at most 5.5 wt%, at most 5.0 wt%, at most 4.5 wt%, or at most 4.0 wt%. In some embodiments, the percentage of Gd2O3 is at most 3.0 wt%, at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Gd2O3.

[0026] In some embodiments, the proportion of YO is in the range of 0-15 wt%, e.g., 0-10 wt%, 1.0-10 wt%, 0-9.0 wt%, 0-8.0 wt%, 0.1-7.0 wt%, 0.2-5.0 wt%, 0.5-2.5 wt%, 0.5-2.0 wt%, 0.5-1.5 wt%, 2.0-8.0 wt%, or 2.5-6.0 wt%. In some embodiments, the proportion of YO is at least 0.1 wt%, at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, or at least 2.5 wt%. In some embodiments, the proportion of Y2O3 is at most 15 wt%, e.g., at most 10 wt%, at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 6.0 wt%, at most 5.0 wt%, at most 2.5 wt%, at most 2.0 wt%, at most 1.5 wt%, or at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Y2O3.

[0027] In some embodiments, the combined weight percentage of GdO and YO is in the range of 0.2-20 wt%, e.g., 0.5-15 wt%, 1.0-10 wt%, 1.5-9 wt%, 2.0-8.0 wt%, 2.5-7.0 wt%, 3.0-6.0 wt%, 3.5-5.5 wt%, or 4.0-5.0 wt%. In some embodiments, the combined weight percentage of GdO and YO is at least 0.2 wt%, e.g., at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, at least 3.5 wt%, or at least 4.0 wt%. In some embodiments, the total weight percentage of GdO and YO is at most 20 wt%, e.g., at most 15 wt%, at most 10 wt%, at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 6.0 wt%, at most 5.5 wt%, or at most 5.0 wt%.

[0028] In some embodiments, the ratio of the sum of the weight fractions of GdO and YO to the weight fraction of SiO is in the range of 0.01 to 0.75, e.g., in the range of 0.02 to 0.60, 0.04 to 0.50, 0.06 to 0.40, 0.08 to 0.30, 0.09 to 0.25, 0.10 to 0.20, or 0.12 to 0.18. In some embodiments, the ratio of the sum of the weight fractions of GdO and YO to the weight fraction of SiO is at least 0.01, e.g., at least 0.02, at least 0.04, at least 0.06, at least 0.08, at least 0.09, at least 0.10, or at least 0.12. In some embodiments, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at most 0.75, e.g., at most 0.60, at most 0.50, at most 0.40, at most 0.30, at most 0.25, or at most 0.20.

[0029] In some embodiments, the percentage of Ta2O5 is in the range of 0 to 10 wt%, e.g., 0 to 9.0 wt%, 0 to 8.0 wt%, 0 to 7.0 wt%, 0.1 to 7.0 wt%, 0.2 to 7.0 wt%, 0.5 to 7.0 wt%, 1.0 to 7.0 wt%, 2.0 to 7.0 wt%, 2.0 to 5.0 wt%, 2.5 to 6.5 wt%, 3.0 to 6.0 wt%, 3.5 to 5.5 wt%, 4.0 to 5.0 wt%, 4.1 to 4.9 wt%, or 4.2 to 4.8 wt%. In some embodiments, the proportion of Ta2O5 is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, at least 3.5 wt%, at least 4.0 wt%, at least 4.1 wt%, or at least 4.2 wt%. In some embodiments, the proportion of Ta2O5 is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 6.5 wt%, at most 6.0 wt%, at most 5.5 wt%, at most 5.0 wt%, at most 4.9 wt%, at most 4.8 wt%, at most 4.5 wt%, at most 4.0 wt%, at most 3.0 wt%, at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some particularly advantageous embodiments, the glass is free of Ta2O5.

[0030] In some embodiments, the sum of the weight fractions of Ta2O5 and SiO2 is in the range of 20-50 wt%, e.g., >20-49 wt%, 21-48 wt%, 22-45 wt%, 25-40 wt%, 27-38 wt%, 29-37 wt%, 30-36 wt%, or 31-35 wt%. In some embodiments, the sum of the weight fractions of Ta2O5 and SiO2 is at least 20 wt%, e.g., greater than 20 wt%, at least 21 wt%, at least 22 wt%, at least 25 wt%, at least 27 wt%, at least 29 wt%, at least 30 wt%, or at least 31 wt%. In some embodiments, the sum of the weight percentages of Ta2O5 and SiO2 is at most 50 wt%, e.g., at most 49 wt%, at most 48 wt%, at most 45 wt%, at most 40 wt%, at most 38 wt%, at most 37 wt%, at most 36 wt%, or at most 35 wt%.

[0031] In some embodiments, the proportions of Y2O3 and Gd2O3 each are at least 0.1 wt%, advantageously at least 0.2 wt% or at least 0.5 wt%. Advantageous upper limits for the sum of Y2O3 and Gd2O3 are set forth above. In some embodiments, the ratio of the weight fraction of Ta2O5 to the sum of the weight fractions of Gd2O3 and Y2O3 is in the range of 0 to 8.0, such as 0.10 to 6.0, 0.20 to 5.0, 0.25 to 4.0, 0.30 to 3.5, 0.35 to 3.0, 0.40 to 2.9, 0.45 to 2.8, 0.45 to 2.5, 0.50 to 2.0, 0.60 to 1.7, 0.70 to 1.5, 0.75 to 1.2, 0.80 to 1.1, or 0.90 to 1.0. In some embodiments, the ratio of the weight fraction of Ta2O5 to the sum of the weight fractions of Gd2O3 and YO3 is at least 0.10, e.g., at least 0.20, at least 0.25, at least 0.30, at least 0.35, at least 0.40, at least 0.45, at least 0.50, at least 0.60, at least 0.70, at least 0.75, at least 0.80, or at least 0.90. In some embodiments, the ratio of the weight fraction of Ta2O5 to the sum of the weight fractions of Gd2O3 and YO3 is at most 8.0, e.g., at most 6.0, at most 5.0, at most 4.0, at most 3.5, at most 3.0, at most 2.9, at most 2.8, at most 2.5, at most 2.0, at most 1.7, at most 1.5, at most 1.2, at most 1.1, at most 1.0, at most 0.8, at most 0.5, at most 0.2, at most 0.1, or even 0.

[0032] In some embodiments, the proportion of BaO is in the range of 0-50 wt%, e.g., 0.1-45 wt%, 1.0-35 wt%, 2.0-30 wt%, 5.0-30 wt%, 10-30 wt%, 15-30 wt%, 15-28 wt%, 17-27 wt%, 17-26 wt%, 17-21 wt%, or 19-24 wt%. In some embodiments, the proportion of BaO is at least 0.1 wt%, e.g., at least 1.0 wt%, at least 2.0 wt%, at least 5.0 wt%, at least 10 wt%, at least 15 wt%, at least 17 wt%, or at least 19 wt%. In some embodiments, the proportion of BaO is at most 50 wt%, e.g., at most 45 wt%, at most 35 wt%, at most 30 wt%, at most 28 wt%, at most 27 wt%, at most 26 wt%, at most 24 wt%, or at most 21 wt%.

[0033] In some embodiments, the proportion of La2O3 is in the range of 0-70 wt%, e.g., 0.1-50 wt%, 2.0-45 wt%, 5.0-40 wt%, 10-30 wt%, 15-25 wt%, 15-24 wt%, 17-22 wt%, 17-28 wt%, or 19-26 wt%. In some embodiments, the proportion of La2O3 is at least 0.1 wt%, e.g., at least 2.0 wt%, at least 5.0 wt%, at least 10 wt%, at least 12 wt%, at least 15 wt%, at least 16 wt%, at least 17 wt%, or at least 19 wt%. In some embodiments, the proportion of La2O3 is at most 70 wt%, e.g., at most 50 wt%, at most 45 wt%, at most 40 wt%, at most 38 wt%, at most 37 wt%, at most 35 wt%, at most 30 wt%, at most 28 wt%, at most 26 wt%, at most 25 wt%, at most 24 wt%, or at most 22 wt%.

[0034] In some embodiments, the sum of the proportions of BaO and La2O3 is in the range of 20 wt% to 60 wt%, e.g., 25 to 55 wt%, 30 to 50 wt%, 32 to 48 wt%, 35 to 45 wt%, or 38 to 44 wt%. In some embodiments, the sum of the proportions of BaO and La2O3 is at least 20 wt%, e.g., at least 25 wt%, at least 30 wt%, at least 32 wt%, at least 35 wt%, or at least 38 wt%. In some embodiments, the sum of the proportions of BaO and La2O3 is at most 60 wt%, e.g., at most 55 wt%, at most 50 wt%, at most 48 wt%, at most 45 wt%, or at most 44 wt%.

[0035] In some embodiments, the ratio of the weight fraction of GdO to the weight fraction of LaO is in the range of 0.01 to 0.75, e.g., 0.02 to 0.50, 0.05 to 0.35, 0.06 to 0.34, 0.07 to 0.33, 0.10 to 0.30, or 0.15 to 0.25. In some embodiments, the ratio of the weight fraction of GdO to the weight fraction of LaO is at least 0.01, e.g., at least 0.02, at least 0.05, at least 0.06, at least 0.07, at least 0.10, or at least 0.15. In some embodiments, the ratio of the weight fraction of GdO to the weight fraction of LaO is at most 0.75, e.g., at most 0.50, at most 0.35, at most 0.34, at most 0.33, at most 0.30, or at most 0.25.

[0036] This advantageously means that the ratio of the weight fraction of La2O3 to the sum of the weight fractions of Gd2O3 and YO3 is at most 10. La2O3 contributes to adjusting the high refractive index of the glass. Therefore, a relatively high content of this component is generally targeted. However, it has been found that, particularly at high La2O3 contents, especially in the range of minimum proportions above 15 wt.%, the meltability of the glass becomes unreasonable. In particular, the melting temperature increases, and the glass tends to devitrify. The inventors have recognized that the presence of Gd2O3 and / or YO3, especially at the minimum contents mentioned here, can have an effect against devitrification. In particular, when the ratio of La2O3 to the sum of the weight fractions of Gd2O3 and YO3 is adjusted as described above, the tendency of the glass to crystallize can be suppressed. It is believed that the reaction of La2O3 with BO3 can lead to crystallized lanthanum borate. However, in particular Gd2O3 and also Y2O3, advantageously the combination of the two, stabilize the network of the glass, so that the tendency to crystallization is reduced and the meltability of the glass is also improved.

[0037] In particular, the presence of Y2O3 and also the presence of Gd2O3, preferably a combination of the two, can contribute to improving the absorption in the blue spectral region of the visible spectrum, and thus the absorption at a wavelength of about 400 nm, so that good transmittance and low absorption occur.

[0038] In some embodiments, the sum of the proportions of La2O3 and Gd2O3 is in the range of 10-50 wt%, e.g., 12-40 wt%, 15-30 wt%, 17-29 wt%, 19-28 wt%, 20-27 wt%, or 21-26 wt%. In some embodiments, the sum of the proportions of La2O3 and Gd2O3 is at least 10 wt%, e.g., at least 12 wt%, at least 15 wt%, at least 17 wt%, at least 19 wt%, at least 20 wt%, or at least 21 wt%. In some embodiments, the sum of the proportions of La2O3 and Gd2O3 is at most 50 wt%, e.g., at most 40 wt%, at most 30 wt%, at most 29 wt%, at most 28 wt%, at most 27 wt%, or at most 26 wt%.

[0039] In some embodiments, the ratio of the weight fraction of Y2O3 to the weight fraction of La2O3 is in the range of 0.01 to 0.15, e.g., 0.02 to 0.10, 0.03 to 0.08, or 0.04 to 0.06. In some embodiments, the ratio of the weight fraction of Y2O3 to the weight fraction of La2O3 is at least 0.01, e.g., at least 0.02, at least 0.03, or at least 0.04. In some embodiments, the ratio of the weight fraction of Y2O3 to the weight fraction of La2O3 is at most 0.15, e.g., at most 0.10, at most 0.08, or at most 0.06.

[0040] In some embodiments, the sum of the proportions of La2O3 and YO3 is in the range of 10-31 wt%, e.g., 12-29 wt%, 14-27 wt%, 16-25 wt%, or 18-23 wt%. In some embodiments, the sum of the proportions of La2O3 and YO3 is at least 10 wt%, e.g., at least 12 wt%, at least 14 wt%, at least 16 wt%, or at least 18 wt%. In some embodiments, the sum of the proportions of La2O3 and YO3 is at most 31 wt%, e.g., at most 29 wt%, at most 27 wt%, at most 25 wt%, or at most 23 wt%.

[0041] In some embodiments, the ratio of the weight fraction of La2O3 to the sum of the weight fractions of Gd2O3 and YO3 is in the range of 1.0 to 10, e.g., 2.0 to 8.0, 2.5 to 7.0, 3.0 to 6.0, or 3.5 to 5.0. In some embodiments, the ratio of the weight fraction of La2O3 to the sum of the weight fractions of Gd2O3 and YO3 is at least 1.0, e.g., at least 2.0, at least 2.5, at least 3.0, or at least 3.5. In some embodiments, the ratio of the weight fraction of La2O3 to the sum of the weight fractions of Gd2O3 and YO3 is at most 10, e.g., at most 8.0, at most 7.0, at most 6.0, or at most 5.0.

[0042] In some embodiments, the sum of the proportions of La2O3, Gd2O3, and YO3 is in the range of 10-50 wt%, e.g., 12-40 wt%, 15-35 wt%, 18-32 wt%, 20-30 wt%, 21-27 wt%, or 22-26 wt%. In some embodiments, the sum of the proportions of La2O3, Gd2O3, and YO3 is at least 10 wt%, e.g., at least 12 wt%, at least 15 wt%, at least 18 wt%, at least 20 wt%, at least 21 wt%, or at least 22 wt%. In some embodiments, the sum of the proportions of La2O3, Gd2O3, and YO3 is at most 50 wt%, e.g., at most 40 wt%, at most 35 wt%, at most 32 wt%, at most 30 wt%, at most 27 wt%, or at most 26 wt%.

[0043] In some embodiments, the proportion of B2O3 is in the range of 0-25 wt%, e.g., 0.1-20 wt%, 0.5-15 wt%, 1.0-13 wt%, 2.0-10 wt%, 2.0-8.0 wt%, 2.0-6.0 wt%, 2.0-5.0 wt%, 2.5-4.5 wt%, 2.5-4.0 wt%, or 3.0-4.0 wt%. In some embodiments, the proportion of B2O3 is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, at least 2.5 wt%, or at least 3.0 wt%. In some embodiments, the proportion of B2O3 is at most 25 wt%, e.g., at most 20 wt%, at most 15 wt%, at most 13 wt%, at most 10 wt%, at most 8.0 wt%, at most 6.0 wt%, at most 5.0 wt%, at most 4.5 wt%, or at most 4.0 wt%.

[0044] According to the present invention, the ratio of the weight fraction of B2O3 to the weight fraction of SiO2 is at most 0.50. In some embodiments, the ratio of the weight fraction of B2O3 to the weight fraction of SiO2 is in the range of 0 to 0.50, e.g., 0 to <0.50, 0.01 to 0.40, 0.02 to 0.30, 0.04 to 0.20, 0.05 to 0.18, 0.06 to 0.17, 0.08 to 0.16, 0.10 to 0.15, or 0.11 to 0.14. In some embodiments, the ratio of the weight fraction of B2O3 to the weight fraction of SiO2 is at least 0.01, e.g., at least 0.02, at least 0.04, at least 0.05, at least 0.06, at least 0.08, at least 0.10, or at least 0.11. In some embodiments, the weight fraction of B2O3 is less than the weight fraction of SiO2. In some embodiments, the ratio of the weight fraction of B2O3 to the weight fraction of SiO2 is at most 0.50, at most 0.40, at most 0.30, at most 0.20, at most 0.18, at most 0.17, at most 0.16, at most 0.15, or at most 0.14.

[0045] In some embodiments, the combined proportions of SiO2 and B2O3 are in the range of 15-50 wt%, e.g., 20-44 wt%, 25-40 wt%, 27-37 wt%, 29-35 wt%, or 30-34 wt%. In some embodiments, the combined proportions of SiO2 and B2O3 are at least 15 wt%, e.g., at least 20 wt%, at least 25 wt%, at least 27 wt%, at least 29 wt%, or at least 30 wt%. In some embodiments, the combined proportions of SiO2 and B2O3 are at most 50 wt%, e.g., at most 44 wt%, at most 40 wt%, at most 37 wt%, at most 35 wt%, or at most 34 wt%.

[0046] In some embodiments, the proportion of Nb2O5 is in the range of 0-10 wt%, e.g., 0-9.0 wt%, 0-8.0 wt%, 0-7.0 wt%, 0.1-5.0 wt%, 0.1-2.0 wt%, 0.1-1.5 wt%, 0.1-1.0 wt%, or 0.1-0.5 wt%. In some embodiments, the proportion of Nb2O5 is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.5 wt%. In some embodiments, the proportion of Nb2O5 is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 5.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Nb2O5.

[0047] In some embodiments, the sum of the proportions of La2O3, Gd2O3, Ta2O5, and Nb2O5 is in the range of 15-50 wt%, e.g., 20-45 wt%, >20-40 wt%, 21-38 wt%, 22-36 wt%, 23-34 wt%, 24-32 wt%, or 25-31 wt%. In some embodiments, the sum of the proportions of La2O3, Gd2O3, Ta2O5, and Nb2O5 is at least 15 wt%, e.g., at least 20 wt%, greater than 20 wt%, at least 21 wt%, at least 22 wt%, at least 23 wt%, at least 24 wt%, or at least 25 wt%. In some embodiments, the sum of the proportions of La2O3, Gd2O3, Ta2O5, and Nb2O5 is at most 50 wt%, at most 45 wt%, at most 40 wt%, at most 38 wt%, at most 36 wt%, at most 34 wt%, at most 32 wt%, or at most 31 wt%.

[0048] In some embodiments, the weight fraction of Y2O3 is greater than the weight fraction of Nb2O5. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of Y2O3 is in the range of 0 to <1.00, e.g., 0.01 to 0.90, 0.02 to 0.75, 0.05 to 0.50, 0.10 to 0.35, or 0.15 to 0.25. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of Y2O3 is at least 0.01, e.g., at least 0.02, at least 0.05, at least 0.10, or at least 0.15. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of Y2O3 is less than 1.00. In some embodiments, the ratio of the weight fraction of NbO to the weight fraction of YO is at most 0.90, at most 0.75, at most 0.50, at most 0.35, or at most 0.25, such as at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0049] In some embodiments, the sum of the proportions of Ta2O5 and Nb2O5 is in the range of 0-10 wt%, for example, 0.1-9.5 wt%, 0.2-9.0 wt%, 0.5-8.5 wt%, 1.0-8.0 wt%, 1.5-7.5 wt%, 2.0-7.0 wt%, 2.5-7.0 wt%, 3.0-7.0 wt%, 3.0-6.5 wt%, 3.5-5.5 wt%, 4.0-5.0 wt%, 4.1-4.9 wt%, or 4.2-4.8 wt%. In some embodiments, the sum of the proportions of Ta2O5 and Nb2O5 is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, at least 3.5 wt%, at least 4.0 wt%, at least 4.1 wt%, or at least 4.2 wt%. In some embodiments, the sum of the proportions of Ta2O5 and Nb2O5 is at most 10 wt%, e.g., at most 9.5 wt%, at most 9.0 wt%, at most 8.5 wt%, at most 8.0 wt%, at most 7.5 wt%, at most 7.0 wt%, at most 6.5 wt%, at most 6.0 wt%, at most 5.5 wt%, at most 5.0 wt%, at most 4.9 wt%, at most 4.8 wt%, at most 4.5 wt%, at most 4.0 wt%, at most 3.0 wt%, at most 2.5 wt%, at most 2.0 wt%, at most 1.5 wt%, or at most 1.0 wt%.

[0050] In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of Ta2O5 is in the range of 0 to 0.30, e.g., 0 to 0.25, 0.01 to 0.20, 0.02 to 0.10, or 0.03 to 0.05. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of Ta2O5 is at least 0.01, at least 0.02, or at least 0.03. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of Ta2O5 is at most 0.30, e.g., at most 0.25, at most 0.20, at most 0.15, at most 0.10, at most 0.08, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0051] In some embodiments, the ratio of the weight fraction of Nb2O5 to the sum of the weight fractions of Gd2O3 and YO3 is in the range of 0 to 0.30, e.g., 0 to 0.25, 0.01 to 0.20, 0.02 to 0.10, or 0.03 to 0.05. In some embodiments, the ratio of the weight fraction of Nb2O5 to the sum of the weight fractions of Gd2O3 and YO3 is at least 0.01, at least 0.02, or at least 0.03. In some embodiments, the ratio of the weight fraction of Nb2O5 to the sum of the weight fractions of Gd2O3 and YO3 is at most 0.30, e.g., at most 0.25, at most 0.20, at most 0.15, at most 0.10, at most 0.08, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0052] According to the present invention, the glass contains ZrO2. The lower limit is 0.1 wt%. In some embodiments, the ZrO2 content is in the range of 0.1-10 wt%, such as 0.1-9.0 wt%, 0.5-8.0 wt%, 1.0-7.0 wt%, 1.0-5.0 wt%, 1.5-4.5 wt%, 2.0-4.5 wt%, 2.0-3.5 wt%, or 2.5-4.0 wt%. In some embodiments, the ZrO2 content is at least 0.1 wt%, at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, or at least 2.5 wt%. In some embodiments, the proportion of ZrO2 is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 5.0 wt%, at most 4.5 wt%, at most 4.0 wt%, or at most 3.5 wt%.

[0053] In some embodiments, the sum of the weight percentages of Nb2O5 and ZrO2 is in the range of 0-15 wt%, e.g., 0.1-12 wt%, 0.2-10 wt%, 0.5-8.0 wt%, 1.0-7.0 wt%, 1.5-6.0 wt%, 2.0-5.0 wt%, or 2.5-4.0 wt%. In some embodiments, the sum of the weight percentages of Nb2O5 and ZrO2 is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, or at least 2.5 wt%. In some embodiments, the sum of the weight percentages of Nb2O5 and ZrO2 is at most 15 wt%, e.g., at most 12 wt%, at most 10 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 6.0 wt%, at most 5.0 wt%, or at most 4.0 wt%.

[0054] In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of ZrO2 is in the range of 0.01 to 0.50, e.g., 0.02 to 0.30, 0.03 to 0.20, or 0.04 to 0.10. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of ZrO2 is at least 0.01, e.g., at least 0.02, at least 0.03, or at least 0.04. In some embodiments, the ratio of the weight fraction of Nb2O5 to the weight fraction of ZrO2 is at most 0.50, e.g., at most 0.30, at most 0.20, at most 0.10, at most 0.07, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0055] In some embodiments, the percentage of LiO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0-1.5 wt%, 0-1.0 wt%, 0.1-1.0 wt%, 0.2-0.9 wt%, 0.3-0.9 wt%, 0.4-0.9 wt%, 0.5-0.9 wt%, 0.5-1.5 wt%, 0.5-1.1 wt%, 0.6-0.9 wt%, or 0.6-0.8 wt%. In some embodiments, the percentage of LiO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the percentage of Li2O is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.5 wt%, at most 1.1 wt%, at most 1.0 wt%, at most 0.9 wt%, at most 0.8 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Li2O.

[0056] In some embodiments, the proportion of NaO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the proportion of NaO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the proportion of Na2O is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Na2O.

[0057] In some embodiments, the sum of the proportions of Li2O and Na2O is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of Li2O and Na2O is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the total proportion of LiO and NaO is at most 10% by weight, e.g., at most 5.0%, at most 4.0%, at most 3.0%, at most 2.0%, at most 1.5%, at most 1.2%, at most 1.1%, at most 1.0%, at most 0.5%, at most 0.3%, at most 0.2%, at most 0.1%, at most 0.05%, or at most 0.01% by weight. In some embodiments, the glass is free of LiO and NaO.

[0058] In some embodiments, the proportion of KO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the proportion of KO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the proportion of KO is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of KO.

[0059] In some embodiments, the sum of the proportions of NaO and KO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of NaO and KO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the total proportion of Na2O and KO is at most 10 wt%, e.g., at most 5.0 wt%, at most 4.0 wt%, at most 3.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.2 wt%, at most 1.1 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Na2O and KO.

[0060] In some embodiments, the sum of the proportions of LiO, NaO, and KO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of LiO, NaO, and KO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the total proportion of LiO, NaO, and KO is at most 10% by weight, e.g., at most 5.0%, at most 4.0%, at most 3.0%, at most 2.0%, at most 1.5%, at most 1.2%, at most 1.1%, at most 1.0%, at most 0.5%, at most 0.3%, at most 0.2%, at most 0.1%, at most 0.05%, or at most 0.01% by weight. In some embodiments, the glass is free of LiO, NaO, and KO.

[0061] In some embodiments, the proportion of RbO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the proportion of RbO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the proportion of RbO is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of RbO.

[0062] In some embodiments, the sum of the proportions of LiO, NaO, KO, and RbO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of LiO, NaO, KO, and RbO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the sum of the proportions of LiO, NaO, KO, and RbO is at most 10% by weight, e.g., at most 5.0%, at most 4.0%, at most 3.0%, at most 2.0%, at most 1.5%, at most 1.2%, at most 1.1%, at most 1.0%, at most 0.5%, at most 0.3%, at most 0.2%, at most 0.1%, at most 0.05%, or at most 0.01% by weight. In some embodiments, the glass is free of LiO, NaO, KO, and RbO.

[0063] In some embodiments, the percentage of CsO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the percentage of CsO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the proportion of CsO is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of CsO.

[0064] In some embodiments, the sum of the proportions of LiO, NaO, KO, and CsO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of LiO, NaO, KO, and CsO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the total proportion of LiO, NaO, KO, and CsO is at most 10% by weight, e.g., at most 5.0%, at most 4.0%, at most 3.0%, at most 2.0%, at most 1.5%, at most 1.2%, at most 1.1%, at most 1.0%, at most 0.5%, at most 0.3%, at most 0.2%, at most 0.1%, at most 0.05%, or at most 0.01% by weight. In some embodiments, the glass is free of LiO, NaO, KO, and CsO.

[0065] In some embodiments, the sum of the proportions of NaO, KO, and CsO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of NaO, KO, and CsO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the total proportion of Na2O, KO, and Cs2O is at most 10 wt%, e.g., at most 5.0 wt%, at most 4.0 wt%, at most 3.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.2 wt%, at most 1.1 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Na2O, KO, and Cs2O.

[0066] In some embodiments, the sum of the proportions of NaO, KO, RbO, and CsO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the sum of the proportions of NaO, KO, RbO, and CsO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the total proportion of NaO, KO, RbO, and CsO is at most 10% by weight, e.g., at most 5.0%, at most 4.0%, at most 3.0%, at most 2.0%, at most 1.5%, at most 1.2%, at most 1.1%, at most 1.0%, at most 0.5%, at most 0.3%, at most 0.2%, at most 0.1%, at most 0.05%, or at most 0.01% by weight. In some embodiments, the glass is free of NaO, KO, RbO, and CsO.

[0067] In this specification, the expressions "R2O" or "ΣR2O" refer to the sum of the alkali metal oxides, i.e., the sum of Li2O, Na2O, K2O, Rb2O, and Cs2O. That is, the proportion of R2O is the sum of the proportions of Li2O, Na2O, K2O, Rb2O, and Cs2O.

[0068] In some embodiments, the proportion of RO is in the range of 0-10 wt%, e.g., 0-5.0 wt%, 0-4.0 wt%, 0-3.0 wt%, 0-2.0 wt%, 0.1-1.5 wt%, 0.1-1.2 wt%, 0.1-1.1 wt%, or 0.2-1.0 wt%. In some embodiments, the proportion of RO is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.3 wt%, at least 0.4 wt%, at least 0.5 wt%, or at least 0.6 wt%. In some embodiments, the proportion of R2O is at most 10 wt%, e.g., at most 5.0 wt%, at most 4.0 wt%, at most 3.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.2 wt%, at most 1.1 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.3 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of R2O.

[0069] In some embodiments, the ratio of the weight percentage of LiO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is in the range of 0.1 to 1.0, e.g., 0.3 to 0.9, 0.5 to 0.8, or 0.6 to 0.7. In some embodiments, the ratio of the weight percentage of LiO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at least 0.1, e.g., at least 0.1, at least 0.3, at least 0.5, at least 0.6, at least 0.7, at least 0.8, at least 0.9, or even 1.0. In some embodiments, the ratio of the weight fraction of LiO to the sum of the weight fractions of LiO, NaO, KO, RbO, and CsO is at most 0.9, e.g., at most 0.8, at most 0.7, at most 0.6, at most 0.5, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0070] In some embodiments, the ratio of the weight percentage of NaO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is in the range of 0 to 0.7, e.g., 0 to 0.5, 0 to 0.4, or 0.1 to 0.3. In some embodiments, the ratio of the weight percentage of NaO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at least 0.1, e.g., at least 0.2 or at least 0.3. In some embodiments, the ratio of the weight percentage of NaO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at most 0.7, at most 0.5, at most 0.4, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0071] In some embodiments, the ratio of the weight percentage of KO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is in the range of 0 to 0.7, e.g., 0 to 0.5, 0 to 0.4, or 0.1 to 0.3. In some embodiments, the ratio of the weight percentage of KO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at least 0.1, e.g., at least 0.2, or at least 0.3. In some embodiments, the ratio of the weight percentage of KO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at most 0.7, at most 0.5, at most 0.4, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0072] In some embodiments, the ratio of the weight percentage of RbO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is in the range of 0 to 0.7, e.g., 0 to 0.5, 0 to 0.4, or 0.1 to 0.3. In some embodiments, the ratio of the weight percentage of RbO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at least 0.1, e.g., at least 0.2, or at least 0.3. In some embodiments, the ratio of the weight percentage of RbO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at most 0.7, at most 0.5, at most 0.4, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0073] In some embodiments, the ratio of the weight percentage of CsO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is in the range of 0 to 0.7, e.g., 0 to 0.5, 0 to 0.4, or 0.1 to 0.3. In some embodiments, the ratio of the weight percentage of CsO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at least 0.1, e.g., at least 0.2, or at least 0.3. In some embodiments, the ratio of the weight percentage of CsO to the sum of the weight percentages of LiO, NaO, KO, RbO, and CsO is at most 0.7, at most 0.5, at most 0.4, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0074] In some embodiments, the ratio of the sum of the weight fractions of NaO and KO to the weight fraction of LiO is in the range of 0 to 2.0, e.g., 0 to 1.5, 0 to 1.0, 0.1 to 0.7, or 0.2 to 0.5. In some embodiments, the ratio of the sum of the weight fractions of NaO and KO to the weight fraction of LiO is at least 0.1, e.g., at least 0.2, at least 0.3, or at least 0.5. In some embodiments, the ratio of the sum of the weight fractions of NaO and KO to the weight fraction of LiO is at most 2.0, e.g., at most 1.5, at most 1.0, at most 0.7, at most 0.5, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0075] In some embodiments, the ratio of the weight fraction of NaO to the weight fraction of LiO is in the range of 0 to 2.0, e.g., 0 to 1.5, 0 to 1.0, 0.1 to 0.7, or 0.2 to 0.5. In some embodiments, the ratio of the weight fraction of NaO to the weight fraction of LiO is at least 0.1, e.g., at least 0.2, at least 0.3, or at least 0.5. In some embodiments, the ratio of the weight fraction of NaO to the weight fraction of LiO is at most 2.0, e.g., at most 1.5, at most 1.0, at most 0.7, at most 0.5, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0076] In some embodiments, the ratio of the weight fraction of K2O to the weight fraction of Li2O is in the range of 0 to 2.0, e.g., 0 to 1.5, 0 to 1.0, 0.1 to 0.7, or 0.2 to 0.5. In some embodiments, the ratio of the weight fraction of K2O to the weight fraction of Li2O is at least 0.1, e.g., at least 0.2, at least 0.3, or at least 0.5. In some embodiments, the ratio of the weight fraction of K2O to the weight fraction of Li2O is at most 2.0, e.g., at most 1.5, at most 1.0, at most 0.7, at most 0.5, at most 0.3, at most 0.2, at most 0.1, or even 0.

[0077] In some embodiments, the percentage of MgO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the percentage of MgO is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.3 wt%. In some embodiments, the percentage of MgO is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of MgO.

[0078] In some embodiments, the CaO content is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the CaO content is at least 0.1 wt%, e.g., at least 0.2 wt% or at least 0.3 wt%. In some embodiments, the CaO content is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of CaO.

[0079] In some embodiments, the percentage of SrO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the percentage of SrO is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.3 wt%. In some embodiments, the percentage of SrO is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of SrO.

[0080] In some embodiments, the sum of the proportions of MgO, CaO, and SrO is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the sum of the proportions of MgO, CaO, and SrO is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.3 wt%. In some embodiments, the sum of the proportions of MgO, CaO, and SrO is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of MgO, CaO, and SrO.

[0081] In some embodiments, the ratio of the sum of the weight fractions of CaO and SrO to the weight fraction of BaO is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the sum of the weight fractions of CaO and SrO to the weight fraction of BaO is at least 0.01, e.g., at least 0.02 or at least 0.05. In some embodiments, the ratio of the sum of the weight fractions of CaO and SrO to the weight fraction of BaO is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0082] In some embodiments, the ratio of the sum of the weight fractions of MgO, CaO, and SrO to the weight fraction of BaO is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the sum of the weight fractions of MgO, CaO, and SrO to the weight fraction of BaO is at least 0.01, e.g., at least 0.02, or at least 0.05. In some embodiments, the ratio of the sum of the weight fractions of MgO, CaO, and SrO to the weight fraction of BaO is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0083] In some embodiments, the sum of the proportions of MgO, CaO, SrO, and BaO is in the range of 0-50 wt%, e.g., 0.1-45 wt%, 1.0-35 wt%, 2.0-30 wt%, 5.0-30 wt%, 10-30 wt%, 15-28 wt%, >15-27 wt%, 17-27 wt%, 17-26 wt%, or 19-24 wt%. In some embodiments, the sum of the proportions of MgO, CaO, SrO, and BaO is at least 0.1 wt%, e.g., at least 1.0 wt%, at least 2.0 wt%, at least 5.0 wt%, at least 10 wt%, at least 15 wt%, and greater than 15 wt%, at least 16 wt%, at least 17 wt%, or at least 19 wt%. In some embodiments, the sum of the proportions of MgO, CaO, SrO, and BaO is at most 50% by weight, e.g., at most 45% by weight, at most 35% by weight, at most 30% by weight, at most 28% by weight, at most 27% by weight, at most 26% by weight, or at most 24% by weight.

[0084] In some embodiments, the sum of the proportions of CaO, SrO, and BaO is in the range of 0-50 wt%, e.g., 0.1-45 wt%, 1.0-35 wt%, 2.0-30 wt%, 5.0-30 wt%, 10-30 wt%, 15-28 wt%, >15-27 wt%, 17-27 wt%, 17-26 wt%, or 19-24 wt%. In some embodiments, the sum of the proportions of CaO, SrO, and BaO is at least 0.1 wt%, e.g., at least 1.0 wt%, at least 2.0 wt%, at least 5.0 wt%, at least 10 wt%, at least 15 wt%, greater than 15 wt%, at least 16 wt%, at least 17 wt%, or at least 19 wt%. In some embodiments, the sum of the proportions of CaO, SrO, and BaO is at most 50% by weight, e.g., at most 45% by weight, at most 35% by weight, at most 30% by weight, at most 28% by weight, at most 27% by weight, at most 26% by weight, or at most 24% by weight.

[0085] In some embodiments, the ZnO content is in the range of 0-30 wt%, e.g., 0.1-25 wt%, 0.5-20 wt%, 1.0-18 wt%, 2.0-18 wt%, 5.0-18 wt%, 5.0-15 wt%, 7.0-14 wt%, 10-18 wt%, 11-17 wt%, 11-16 wt%, 12-15 wt%, 12-15.0 wt%, 12-<15.0 wt%, or 12-14.5 wt%. In some embodiments, the ZnO content is at least 0.1 wt%, e.g., at least 0.5 wt%, at least 1.0 wt%, at least 2.0 wt%, at least 5.0 wt%, at least 7.0 wt%, at least 8.0 wt%, at least 10 wt%, at least 11 wt%, or at least 12 wt%. In some embodiments, the percentage of ZnO is at most 30 wt%, e.g., at most 25 wt%, at most 20 wt%, at most 18 wt%, at most 17 wt%, at most 16 wt%, at most 15 wt%, at most 15.0 wt%, less than 15.0 wt%, at most 14.5 wt%, or at most 14.0 wt%.

[0086] In some embodiments, the sum of the proportions of MgO, CaO, SrO, BaO, and ZnO is in the range of 0-70% by weight, e.g., 0.1-65%, 1.0-60%, 2.0-55%, 5.0-50%, 10-45%, 15-42%, 20-41%, 25-40%, 30-39%, 31-38%, or 32-37% by weight. In some embodiments, the sum of the proportions of MgO, CaO, SrO, BaO, and ZnO is at least 0.1% by weight, e.g., at least 1.0%, at least 2.0%, at least 5.0%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 31%, or at least 32% by weight. In some embodiments, the sum of the proportions of MgO, CaO, SrO, BaO, and ZnO is at most 70% by weight, e.g., at most 65% by weight, at most 60% by weight, at most 55% by weight, at most 50% by weight, at most 45% by weight, at most 42% by weight, at most 41% by weight, at most 40% by weight, at most 39% by weight, at most 38% by weight, or at most 37% by weight.

[0087] In some embodiments, the combined proportions of BaO and ZnO are in the range of 0-70 wt%, e.g., 0.1-65 wt%, 1.0-60 wt%, 2.0-55 wt%, 5.0-50 wt%, 10-45 wt%, 15-42 wt%, 20-41 wt%, 25-40 wt%, 30-39 wt%, 31-38 wt%, or 32-37 wt%. In some embodiments, the combined proportions of BaO and ZnO are at least 0.1 wt%, e.g., at least 1.0 wt%, at least 2.0 wt%, at least 5.0 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 31 wt%, or at least 32 wt%. In some embodiments, the combined proportion of BaO and ZnO is at most 70% by weight, e.g., at most 65% by weight, at most 60% by weight, at most 55% by weight, at most 50% by weight, at most 45% by weight, at most 42% by weight, at most 41% by weight, at most 40% by weight, at most 39% by weight, at most 38% by weight, or at most 37% by weight.

[0088] In some embodiments, the TiO content is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the TiO content is at least 0.1 wt%, e.g., at least 0.2 wt% or at least 0.3 wt%. In some embodiments, the TiO content is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of TiO.

[0089] In some embodiments, the sum of the weight percentages of TiO2, Nb2O5, and ZrO2 is in the range of 0-15 wt%, e.g., 0.1-12 wt%, 0.2-10 wt%, 0.5-8.0 wt%, 1.0-7.0 wt%, 1.5-6.0 wt%, 2.0-5.0 wt%, or 2.5-4.0 wt%. In some embodiments, the sum of the weight percentages of TiO2, Nb2O5, and ZrO2 is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, or at least 2.5 wt%. In some embodiments, the sum of the weight percentages of TiO2, Nb2O5, and ZrO2 is at most 15 wt%, e.g., at most 12 wt%, at most 10 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 6.0 wt%, at most 5.0 wt%, or at most 4.0 wt%.

[0090] In some embodiments, the ratio of the weight fraction of Nb2O5 to the sum of the weight fractions of Nb2O5, TiO2, and ZrO2 is in the range of 0.01 to 0.40, e.g., 0.02 to 0.30, 0.03 to 0.20, or 0.04 to 0.10. In some embodiments, the ratio of the weight fraction of Nb2O5 to the sum of the weight fractions of Nb2O5, TiO2, and ZrO2 is at least 0.01, e.g., at least 0.02, at least 0.03, or at least 0.04. In some embodiments, the ratio of the weight fraction of Nb2O5 to the sum of the weight fractions of Nb2O5, TiO2, and ZrO2 is at most 0.40, e.g., at most 0.30, at most 0.20, at most 0.10, at most 0.07, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0091] In some embodiments, the ratio of the weight fraction of TiO2 to the weight fraction of Nb2O5 is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the weight fraction of TiO2 to the weight fraction of Nb2O5 is at least 0.01, e.g., at least 0.02 or at least 0.05. In some embodiments, the ratio of the weight fraction of TiO2 to the weight fraction of Nb2O5 is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0092] In some embodiments, the sum of the proportions of TiO2 and Nb2O5 is in the range of 0-10 wt%, e.g., 0-9.0 wt%, 0-8.0 wt%, 0-7.0 wt%, 0.1-5.0 wt%, 0.1-2.0 wt%, 0.1-1.5 wt%, 0.1-1.0 wt%, or 0.1-0.5 wt%. In some embodiments, the sum of the proportions of TiO2 and Nb2O5 is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.5 wt%. In some embodiments, the total proportion of TiO2 and Nb2O5 is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 5.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of TiO2 and Nb2O5.

[0093] In some embodiments, the ratio of the sum of the weight fractions of TiO2 and Nb2O5 to the weight fraction of SiO2 is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the sum of the weight fractions of TiO2 and Nb2O5 to the weight fraction of SiO2 is at least 0.01, e.g., at least 0.02 or at least 0.05. In some embodiments, the ratio of the sum of the weight fractions of TiO2 and Nb2O5 to the weight fraction of SiO2 is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0094] In some embodiments, the WO3 content is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the WO3 content is at least 0.1 wt%, e.g., at least 0.2 wt% or at least 0.3 wt%. In some embodiments, the WO3 content is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of WO3.

[0095] In some embodiments, the ratio of the sum of the weight fractions of Nb2O5 and TiO2 to the sum of the weight fractions of Nb2O5, TiO2, Ta2O5, and WO3 is in the range of 0 to 0.30, e.g., 0 to 0.25, 0.01 to 0.20, 0.02 to 0.10, or 0.03 to 0.05. In some embodiments, the ratio of the sum of the weight fractions of Nb2O5 and TiO2 to the sum of the weight fractions of Nb2O5, TiO2, Ta2O5, and WO3 is at least 0.01, at least 0.02, or at least 0.03. In some embodiments, the ratio of the sum of the weight fractions of Nb2O5 and TiO2 to the sum of the weight fractions of Nb2O5, TiO2, Ta2O5, and WO3 is at most 0.30, e.g., at most 0.25, at most 0.20, at most 0.15, at most 0.10, at most 0.08, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0096] In some embodiments, the sum of the proportions of TiO2, Nb2O5, and WO3 is in the range of 0-10 wt%, e.g., 0-9.0 wt%, 0-8.0 wt%, 0-7.0 wt%, 0.1-5.0 wt%, 0.1-2.0 wt%, 0.1-1.5 wt%, 0.1-1.0 wt%, or 0.1-0.5 wt%. In some embodiments, the sum of the proportions of TiO2, Nb2O5, and WO3 is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.5 wt%. In some embodiments, the sum of the proportions of TiO2, Nb2O5, and WO3 is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 5.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of TiO2, Nb2O5, and WO3.

[0097] In some embodiments, the sum of the proportions of Nb2O5 and WO3 is in the range of 0-10 wt%, e.g., 0-9.0 wt%, 0-8.0 wt%, 0-7.0 wt%, 0.1-5.0 wt%, 0.1-2.0 wt%, 0.1-1.5 wt%, 0.1-1.0 wt%, or 0.1-0.5 wt%. In some embodiments, the sum of the proportions of Nb2O5 and WO3 is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.5 wt%. In some embodiments, the sum of the proportions of Nb2O5 and WO3 is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 5.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Nb2O5 and WO3.

[0098] In some embodiments, the ratio of the weight fraction of WO3 to the weight fraction of ZnO is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the weight fraction of WO3 to the weight fraction of ZnO is at least 0.01, e.g., at least 0.02 or at least 0.05. In some embodiments, the ratio of the weight fraction of WO3 to the weight fraction of ZnO is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0099] In some embodiments, the ratio of the weight fraction of WO3 to the weight fraction of Ta2O5 is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the weight fraction of WO3 to the weight fraction of Ta2O5 is at least 0.01, e.g., at least 0.02 or at least 0.05. In some embodiments, the ratio of the weight fraction of WO3 to the weight fraction of Ta2O5 is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0100] In some embodiments, the ratio of the sum of the weight fractions of WO3 and TiO2 to the sum of the weight fractions of Nb2O5 and SiO2 is in the range of 0 to 0.20, e.g., 0 to 0.15, 0 to 0.10, or 0.01 to 0.05. In some embodiments, the ratio of the sum of the weight fractions of WO3 and TiO2 to the sum of the weight fractions of Nb2O5 and SiO2 is at least 0.01, e.g., at least 0.02 or at least 0.05. In some embodiments, the ratio of the sum of the weight fractions of WO3 and TiO2 to the sum of the weight fractions of Nb2O5 and SiO2 is at most 0.20, e.g., at most 0.15, at most 0.10, at most 0.05, at most 0.02, at most 0.01, or even 0.

[0101] In some embodiments, the Al2O3 content is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the Al2O3 content is at least 0.1 wt%, e.g., at least 0.2 wt% or at least 0.3 wt%. In some embodiments, the Al2O3 content is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Al2O3.

[0102] In some embodiments, the percentage of Ga2O3 is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the percentage of Ga2O3 is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.3 wt%. In some embodiments, the percentage of Ga2O3 is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is Ga2O3-free.

[0103] In some embodiments, the sum of the proportions of Al2O3 and Ga2O3 is in the range of 0-5.0 wt%, e.g., 0-2.0 wt%, 0.1-2.0 wt%, 0-1.5 wt%, 0.2-1.5 wt%, 0-1.0 wt%, 0.3-1.0 wt%, 0-0.5 wt%, 0-0.2 wt%, or 0-0.1 wt%. In some embodiments, the sum of the proportions of Al2O3 and Ga2O3 is at least 0.1 wt%, e.g., at least 0.2 wt% or at least 0.3 wt%. In some embodiments, the sum of the proportions of Al2O3 and Ga2O3 is at most 5.0 wt%, e.g., at most 2.0 wt%, at most 1.0 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Al2O3 and Ga2O3.

[0104] In some embodiments, the sum of the proportions of B2O3, Al2O3, and Ga2O3 is in the range of 0-25 wt%, e.g., 0.1-20 wt%, 0.5-15 wt%, 1.0-13 wt%, 2.0-10 wt%, 2.0-8.0 wt%, 2.0-6.0 wt%, 2.0-5.0 wt%, 2.5-4.5 wt%, or 2.5-4.0 wt%. In some embodiments, the sum of the proportions of B2O3, Al2O3, and Ga2O3 is at least 0.1 wt%, e.g., at least 0.2 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, or at least 2.5 wt%. In some embodiments, the sum of the proportions of B2O3, Al2O3, and Ga2O3 is at most 25 wt%, e.g., at most 20 wt%, at most 15 wt%, at most 13 wt%, at most 10 wt%, at most 8.0 wt%, at most 6.0 wt%, at most 5.0 wt%, at most 4.5 wt%, or at most 4.0 wt%.

[0105] In some embodiments, the combined weight percentage of SiO2 and Al2O3 is in the range of 10-55 wt%, e.g., 15-45 wt%, 17-40 wt%, 18-35 wt%, 20-35 wt%, 22-35 wt%, 23-34 wt%, 24-33 wt%, or 25-32 wt%. In some embodiments, the combined weight percentage of SiO2 and Al2O3 is at least 10 wt%, e.g., at least 15 wt%, at least 17 wt%, at least 18 wt%, at least 20 wt%, at least 22 wt%, at least 23 wt%, at least 24 wt%, or at least 25 wt%. In some embodiments, the combined weight percentage of SiO2 and Al2O3 is at most 55 wt%, at most 45 wt%, at most 40 wt%, at most 35 wt%, at most 34 wt%, at most 33 wt%, or at most 32 wt%.

[0106] In some embodiments, the sum of the proportions of Bi2O3, La2O3, Gd2O3, Ta2O5, TiO2, Nb2O5, and WO3 is in the range of 15-50 wt%, e.g., 20-45 wt%, >20-40 wt%, 21-38 wt%, 22-36 wt%, 23-34 wt%, 24-32 wt%, or 25-31 wt%. In some embodiments, the sum of the proportions of Bi2O3, La2O3, Gd2O3, Ta2O5, TiO2, Nb2O5, and WO3 is at least 15 wt%, e.g., at least 20 wt% and greater than 20 wt%, at least 21 wt%, at least 22 wt%, at least 23 wt%, at least 24 wt%, or at least 25 wt%. In some embodiments, the sum of the proportions of Bi2O3, La2O3, Gd2O3, Ta2O5, TiO2, Nb2O5, and WO3 is at most 50 wt%, at most 45 wt%, at most 40 wt%, at most 38 wt%, at most 36 wt%, at most 34 wt%, at most 32 wt%, or at most 31 wt%.

[0107] In some embodiments, the sum of the weight percentages of F, Bi2O3, TiO2, WO3, Nb2O5, and K2O is in the range of 0-10 wt%, e.g., 0-9.0 wt%, 0-8.0 wt%, 0-7.0 wt%, 0.1-5.0 wt%, 0.1-2.0 wt%, 0.1-1.5 wt%, 0.1-1.0 wt%, or 0.1-0.5 wt%. In some embodiments, the sum of the weight percentages of F, Bi2O3, TiO2, WO3, Nb2O5, and K2O is at least 0.1 wt%, e.g., at least 0.2 wt%, or at least 0.5 wt%. In some embodiments, the sum of the weight percentages of F, Bi2O3, TiO2, WO3, Nb2O5, and KO is at most 10 wt%, e.g., at most 9.0 wt%, at most 8.0 wt%, at most 7.0 wt%, at most 5.0 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.0 wt%, less than 1.0 wt%, at most 0.9 wt%, at most 0.8 wt%, at most 0.7 wt%, at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of F, Bi2O3, TiO2, WO3, Nb2O5, and KO.

[0108] In some embodiments, the glass comprises a fining agent selected from Sb2O3, As2O3, SO3, SnO2, Cl, and combinations of two or more thereof, particularly in a total proportion of 0.01 to 2.00 wt.%, such as 0.01 to 1.50 wt.%, 0.01 to 1.00 wt.%, 0.01 to 0.75 wt.%, 0.01 to 0.50 wt.%, 0.01 to 0.25 wt.%, 0.01 to 0.20 wt.%, 0.01 to 0.15 wt.%, 0.02 to 0.10 wt.%, 0.02 to 0.08 wt.%, 0.02 to 0.06 wt.%, or 0.03 to 0.05 wt.%. In some embodiments, the glass comprises a fining agent selected from SbO, AsO, SO, SnO, Cl, and combinations of two or more thereof, particularly in a total proportion of at least 0.01 wt.%, at least 0.02 wt.%, or at least 0.03 wt.%. In some embodiments, the glass comprises a fining agent selected from SbO, AsO, SO, SnO, Cl, and combinations of two or more thereof, particularly in a total proportion of at most 2.00 wt.%, at most 1.50 wt.%, at most 1.00 wt.%, at most 0.75 wt.%, at most 0.50 wt.%, at most 0.25 wt.%, at most 0.20 wt.%, at most 0.15 wt.%, at most 0.10 wt.%, at most 0.08 wt.%, at most 0.06 wt.%, or at most 0.05 wt.%.

[0109] In some embodiments, the percentage of Sb2O3 is in the range of 0-2.00 wt%, e.g., 0-1.50 wt%, 0-1.00 wt%, 0-0.75 wt%, 0-0.50 wt%, 0.01-0.25 wt%, 0.01-0.20 wt%, 0.01-0.15 wt%, 0.02-0.10 wt%, 0.02-0.08 wt%, 0.02-0.06 wt%, or 0.03-0.05 wt%. In some embodiments, the percentage of Sb2O3 is at least 0.01 wt%, at least 0.02 wt%, or at least 0.03 wt%. In some embodiments, the percentage of Sb2O3 is at most 2.00 wt%, at most 1.50 wt%, at most 1.00 wt%, at most 0.75 wt%, at most 0.50 wt%, at most 0.25 wt%, at most 0.20 wt%, at most 0.15 wt%, at most 0.10 wt%, at most 0.08 wt%, at most 0.06 wt%, at most 0.05 wt%, at most 0.04 wt%, at most 0.03 wt%, at most 0.02 wt%, or 0.01 wt%. In some embodiments, the glass is free of Sb2O3.

[0110] In some embodiments, the percentage of As2O3 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of As2O3.

[0111] In some embodiments, the proportion of SO3 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of SO3.

[0112] In some embodiments, the total proportion of oxides of Sn, particularly the total proportion of SnO2 and SnO, is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of oxides of Sn, particularly SnO2 and SnO.

[0113] In some embodiments, the percentage of Cl is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is Cl-free.

[0114] In some embodiments, the proportion of AgO is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of AgO.

[0115] In some embodiments, the percentage of at least one of Cr2O3, NiO, Fe2O3, and Pt is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the percentage of each of Cr2O3, NiO, Fe2O3, and Pt is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the total percentage of Cr2O3, NiO, Fe2O3, and Pt is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of at least one of Cr2O3, NiO, Fe2O3, and Pt. In some embodiments, the glass is free of Cr2O3, NiO, Fe2O3, and Pt.

[0116] In some embodiments, the Bi2O3 content is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. 3s Does not include.

[0117] In some embodiments, the proportion of Tb2O3 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Tb2O3.

[0118] In some embodiments, the proportion of Eu2O3 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Eu2O3.

[0119] In some embodiments, the proportion of at least one of F, Cl, and I is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the proportion of each of F, Cl, and I is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the total proportion of F, Cl, and I is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass does not contain at least one of F, Cl, and I. In some embodiments, the glass does not contain F, Cl, or I.

[0120] In some embodiments, the proportion of GeO2 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of GeO2.

[0121] In some embodiments, the proportion of P2O5 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of P2O5.

[0122] In some embodiments, the sum of the proportions of Al2O3, GeO2, Ga2O3, and P2O5 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of Al2O3, GeO2, Ga2O3, and P2O5.

[0123] In some embodiments, the total proportion of GeO2 and Ga2O3 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of GeO2 and Ga2O3.

[0124] In some embodiments, the proportion of CuO is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of CuO.

[0125] In some embodiments, the sum of the percentages of oxides of V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Ce, Pr, and Er is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of oxides of V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Ce, Pr, and Er.

[0126] In some embodiments, the sum of the proportions of CeO2 and Tb2O3 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of CeO2 and Tb2O3.

[0127] In some embodiments, the proportion of CeO2 is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is free of CeO2.

[0128] In some embodiments, the total proportion of sulfur oxides, in particular the total proportion of SO2 and SO3, is at most 1.0 wt%, for example at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass is sulfur-free, in particular SO2 and SO3-free.

[0129] In some embodiments, the percentage of at least one of As2O3 and PbO is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the percentage of each of As2O3 and PbO is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the total percentage of As2O3 and PbO is at most 1.0 wt%, e.g., at most 0.5 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, or at most 0.01 wt%. In some embodiments, the glass does not contain at least one of As2O3 and PbO. In some embodiments, the glass does not contain As2O3 and PbO.

[0130] When a glass is described in this disclosure as "free" of a certain component or as having a particular component, this means that the component may be present in the glass as an impurity, i.e., not added in a substantial amount. An insubstantial amount is less than 100 ppm (by weight), less than 75 ppm (by weight), less than 50 ppm (by weight), less than 25 ppm (by weight), and especially less than 10 ppm (by weight).

[0131] In some preferred embodiments, the glass comprises the following components in the stated proportions [wt %]: [Table 1]

[0132] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 2]

[0133] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 3]

[0134] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 4]

[0135] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 5]

[0136] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 6]

[0137] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 7]

[0138] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 8]

[0139] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 9]

[0140] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 10]

[0141] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 11]

[0142] In a further preferred embodiment, the glass comprises the following components in the stated proportions [% by weight]: [Table 12]

[0143] optical properties In some embodiments, the glass has a net transmittance of at least 0.900, e.g., at least 0.910, at least 0.920, at least 0.930, at least 0.940, at least 0.950, at least 0.960, at least 0.965, at least 0.970, at least 0.975, or at least 0.980, at a sample thickness of 25 mm and a wavelength of 380 nm. In some embodiments, the glass has a net transmittance of at most 0.999, at most 0.998, at most 0.995, at most 0.990, or at most 0.985, at a sample thickness of 25 mm and a wavelength of 380 nm. In some embodiments, the glass has a net transmittance in the range of 0.900 to 0.999, for example, 0.910 to 0.999, 0.920 to 0.998, 0.930 to 0.998, 0.940 to 0.995, 0.950 to 0.995, 0.960 to 0.995, 0.965 to 0.990, 0.970 to 0.990, 0.975 to 0.985, or 0.980 to 0.985, at a sample thickness of 25 mm and a wavelength of 380 nm.

[0144] In some embodiments, the glass has a net transmittance of at least 0.900, e.g., at least 0.910, at least 0.920, at least 0.930, at least 0.940, at least 0.950, at least 0.960, at least 0.965, at least 0.970, at least 0.975, or at least 0.980, over a 25 mm sample thickness and the entire wavelength range from 380 nm to 700 nm. In some embodiments, the glass has a net transmittance of at most 0.999, at most 0.998, at most 0.995, at most 0.990, or at most 0.985, over a 25 mm sample thickness and the entire wavelength range from 380 nm to 700 nm. In some embodiments, the glass has a net transmittance in the range of 0.900 to 0.999, for example, in the range of 0.910 to 0.999, 0.920 to 0.998, 0.930 to 0.998, 0.940 to 0.995, 0.950 to 0.995, 0.960 to 0.995, 0.965 to 0.990, 0.970 to 0.990, 0.975 to 0.985, or 0.980 to 0.985, for a sample thickness of 25 mm and over the full wavelength range of 380 nm to 700 nm.

[0145] In some embodiments, the glass has an attenuation at 380 nm in the range of 0.5 to <10 dB / m, e.g., 1.0 to <5.0 dB / m, 1.5 to 4.0 dB / m, or 2.0 to 3.5 dB / m. In some embodiments, the glass has an attenuation at 380 nm of at least 0.5 dB / m, e.g., at least 1.0 dB / m, at least 1.5 dB / m, or at least 2.0 dB / m. In some embodiments, the glass has an attenuation of less than 10 dB / m, e.g., less than 5.0 dB / m, at most 4.0 dB / m, or at most 3.5 dB / m, at a wavelength of 380 nm.

[0146] In some embodiments, the ratio of the net transmittance at a wavelength of 380 nm to the net transmittance at a wavelength of 600 nm for each 25 mm sample thickness is at least 0.900, e.g., at least 0.910, at least 0.920, at least 0.930, at least 0.940, at least 0.950, at least 0.960, at least 0.965, at least 0.970, at least 0.975, or at least 0.980. In some embodiments, the ratio of the net transmittance at a wavelength of 380 nm to the net transmittance at a wavelength of 600 nm for each 25 mm sample thickness is at most 0.999, at most 0.998, at most 0.995, at most 0.990, or at most 0.985. In some embodiments, the ratio of the net transmittance at a wavelength of 380 nm to the net transmittance at a wavelength of 600 nm, each at a sample thickness of 25 mm, is in the range of 0.900 to 0.999, e.g., in the range of 0.910 to 0.999, 0.920 to 0.998, 0.930 to 0.998, 0.940 to 0.995, 0.950 to 0.995, 0.960 to 0.995, 0.965 to 0.990, 0.970 to 0.990, 0.975 to 0.985, or 0.980 to 0.985.

[0147] In some embodiments, the refractive index n d is in the range of 1.60 to 1.85, for example, in the range of 1.65 to 1.80, 1.67 to 1.77, 1.68 to 1.75, 1.69 to 1.74, or 1.70 to 1.73. In some embodiments, the refractive index n d is at least 1.60, e.g., at least 1.65, at least 1.67, at least 1.68, at least 1.69, or at least 1.70. In some embodiments, the refractive index n d is at most 1.85, e.g., at most 1.80, at most 1.77, at most 1.75, at most 1.74, or at most 1.73.

[0148] In some embodiments, the Abbe number v d is in the range of 35 to 60, for example, in the range of 40 to 55, 42 to 54, 43 to 53, 44 to 52, or 45 to 51. In some embodiments, the Abbe number vd is at least 35, e.g., at least 40, at least 42, at least 43, at least 44, or at least 45. In some embodiments, the Abbe number v d is at most 60, for example at most 55, at most 54, at most 53, at most 52 or at most 51.

[0149] Crystallization resistance The glass of the present invention not only has excellent optical properties. The glass of the present invention is also characterized by a particularly high resistance to crystallization. This is of great importance for manufacturing in fiber drawing. Without the glass of the present invention, devitrification crystals would form, especially on the glass surface, which could impair, for example, the molding of the glass. Therefore, the glass of the present invention has good devitrification stability. This is particularly important for large dimensions and thick walls.

[0150] The measure of crystallization resistance is the maximum crystallization rate KG max KG max The smaller the value, the higher the resistance to crystallization. In this disclosure, the terms "crystallization resistance" and "devitrification stability" are used synonymously. max represents the maximum crystallization rate (usually expressed in μm / min). Measurement of the crystallization rate is known. Preferably, the crystallization rate is measured along the formed crystal, i.e., along its maximum extension.

[0151] "UEG" is understood according to the present invention to mean the so-called lower devitrification limit. This is the temperature at which the material begins to devitrify as the temperature increases. Above a certain temperature, called the upper devitrification limit (OEG) or liquidus temperature, no crystallization occurs, even after a relatively long period of time. The values ​​of UEG and OEG are usually different for different glasses.

[0152] When referring to crystallization, crystallization here occurs at a temperature above the lower devitrification limit (UEG) and below the upper devitrification limit (OEG), i.e., in the region between the UEG and OEG. Therefore, the temperature at which the maximum crystallization rate is achieved is also between the UEG and OEG. Therefore, the maximum crystallization rate KG max To determine KG, the glass must be heated to a temperature between UEG and OEG. Exactly where maximum crystallization occurs in the region between UEG and OEG is usually not known for a given glass, so the KG max In this way, the UEG and OEG themselves can also be determined as the lower or upper limits of the region where crystallization occurs.

[0153] When referring to the lower devitrification limit UEG in this disclosure, this means the UEG calculated by heat treating the glass in a gradient furnace with controlled rising temperature for a 5 minute hold time, unless otherwise specified.

[0154] In particular, the crystallization rate is determined by heat-treating the glass in a gradient furnace with ramping temperature control over a holding time of 5 minutes or 1 hour. A gradient furnace is a furnace with different heating zones, i.e., different temperature regions. Ramping temperature control means that the temperature of the glass before being introduced into the gradient furnace is lower than the temperature in all regions of the furnace. This means that upon introduction into the furnace, the temperature of the glass increases regardless of which region of the furnace the glass is introduced into. Therefore, devitrification measurements are performed in a gradient furnace (already at high temperature) divided into several different temperature zones, in particular with a 5-minute or 1-hour heat treatment. This is a spatially resolved temperature gradient in the gradient furnace, not a time-resolved gradient, due to the spatially resolved division of the gradient furnace into different temperature regions.

[0155] The gradient furnace is divided into multiple heating zones, allowing different temperatures to be tested simultaneously. This is a particular advantage of the gradient furnace. For example, the minimum temperature may be 950°C and the maximum temperature 1250°C, or the minimum temperature may be 700°C and the maximum temperature 1000°C. These temperatures allow the crystallization rate at different temperatures in the region between UEG and OEG to be determined, thereby allowing the maximum crystallization rate KG to be determined from a comparison of potentially different crystallization rates in the region between UEG and OEG. max Preferably, the temperature is selected so that the maximum crystallization rate can be determined. If the UEG and OEG are unknown, it is advantageous to test a relatively large area of ​​temperatures to enable the UEG and OEG to be determined.

[0156] Therefore, when the glass is heat treated in a gradient furnace with a temperature rise control for a holding time of 1 hour, the glass has a maximum crystallization rate (KG) of 15 μm / min at a maximum in the temperature range of, for example, 700°C to 1250°C. max ) does not mean that the entire temperature range between 700°C and 1250°C must be present in the gradient furnace. If it is known that the OEG for a particular glass is, for example, 1000°C, there is no need to test temperatures above 1000°C in the gradient furnace, since crystallization will not occur at that temperature anyway and the maximum crystallization rate KG max will exist below 1000°C. Similarly, if it is known that the UEG for a given glass is, for example, 950°C, it is not necessary to test temperatures below 950°C in a gradient furnace, since at that temperature no crystallization occurs anyway and the maximum crystallization rate KG max This is because the temperature will be above 950°C.

[0157] If devitrification does not occur, crystallization does not occur, and therefore KG max cannot be determined. In this case, KG max A value of 0 μm / min can be assumed for

[0158] The crystallization rate is preferably determined using glass powder, in particular glass powder having a diameter of 1.6 mm to 4 mm. The glass powder is preferably placed on a support, for example a platinum support, for heat treatment in a gradient furnace. The support may have recesses, in particular recesses for accommodating glass particles, and holes on the underside of each recess, so that the crystallization rate can be determined microscopically following heat treatment. Taking into account the preferred size of the glass particles, the recesses preferably each have a diameter of 4 mm and the holes each have a diameter of 1 mm. Following heat treatment, it can be determined microscopically which crystallization rate was present in which temperature range. The maximum crystallization rate observed is referred to as the maximum crystallization rate KG. max The UEG and OEG can be determined as the lower and upper limits of the temperature range where crystallization occurs. Mapping individual glass particles to different temperature zones in a gradient furnace is straightforward because it is known which temperature exists at which location in the furnace and where the glass particle is located in the furnace.

[0159] The glass of the present invention exhibits a maximum crystallization rate (KG) in the temperature range of 700°C to 1250°C (particularly 800°C to 1200°C, 850°C to 1150°C, 900°C to 1100°C, or 950°C to 1050°C) in some embodiments when the glass is heat treated in a gradient furnace with ramp temperature control for a holding time of 1 hour. max ) has high devitrification stability of up to 7.5 μm / min. In some embodiments, KG maxis at most 6.0 μm / min, e.g., at most 5.0 μm / min, at most 4.0 μm / min, at most 3.0 μm / min, at most 2.5 μm / min, at most 2.0 μm / min, at most 1.5 μm / min, at most 1.0 μm / min, at most 0.5 μm / min, at most 0.2 μm / min, at most 0.1 μm / min, or even 0 μm / min, in the temperature range of 700°C to 1250°C (particularly 800°C to 1200°C, 850°C to 1150°C, 900°C to 1100°C, or 950°C to 1050°C) when the glass is heat treated in a gradient furnace with ramp temperature control for a holding time of 1 hour. max is at least 0.1 μm / min, e.g., at least 0.2 μm / min, at least 0.5 μm / min, at least 1.0 μm / min, at least 1.5 μm / min, at least 2.0 μm / min, at least 2.5 μm / min, or at least 3.0 μm / min, in the temperature range of 700°C to 1250°C (particularly 800°C to 1200°C, 850°C to 1150°C, 900°C to 1100°C, or 950°C to 1050°C), when the glass is heat-treated in a gradient furnace with ramping temperature control for a holding time of 1 hour. max is in the range of 0 to 7.5 μm / min, for example in the range of 0 to 6.0 μm / min, 0.1 to 5.0 μm / min, 0.2 to 4.0 μm / min, 0.5 to 3.0 μm / min, 1.0 to 2.5 μm / min, 1.5 to 2.0 μm / min, 1.0 to 1.5 μm / min, 0.5 to 1.0 μm / min, 0.2 to 0.5 μm / min, 0.1 to 0.2 μm / min or 0 to 0.1 μm / min, in the temperature range of 700°C to 1250°C (particularly 800°C to 1200°C, 850°C to 1150°C, 900°C to 1100°C or 950°C to 1050°C), when the glass is heat treated in a gradient furnace with ramp temperature control for a holding time of 1 hour.

[0160] In some embodiments, the OEG is in the range of 900°C to 1400°C, e.g., 950°C to 1350°C, 1000°C to 1300°C, 1050°C to 1250°C, or 1100°C to 1200°C, when the glass is heat treated for a 1 hour hold time in a gradient furnace with controlled rising temperature. In some embodiments, the OEG is at least 900°C, e.g., at least 950°C, at least 1000°C, at least 1050°C, or at least 1100°C, when the glass is heat treated for a 1 hour hold time in a gradient furnace with controlled rising temperature. In some embodiments, the OEG is up to 1400°C, e.g., up to 1350°C, up to 1300°C, up to 1250°C, or up to 1200°C, when the glass is heat treated for a 1 hour hold time in a gradient furnace with controlled rising temperature.

[0161] The glasses of the present invention exhibit a maximum crystallization rate (KG) of 1.0001 when heat treated in a gradient furnace with ramping temperature control for a holding time of 5 minutes. max In some embodiments, KG has high devitrification stability of up to 25 μm / min in a temperature range of 700°C to 1250°C (particularly 850°C to 1200°C, 900°C to 1150°C, 950°C to 1100°C, or 100°C to 1050°C). max is at most 20 μm / min, e.g., at most 15 μm / min, at most 12 μm / min, at most 10 μm / min, at most 7.5 μm / min, at most 5.0 μm / min, at most 4.0 μm / min, at most 3.0 μm / min, at most 2.0 μm / min, at most 1.0 μm / min, at most 0.5 μm / min, at most 0.2 μm / min, at most 0.1 μm / min, or even 0 μm / min, in the temperature range of 700°C to 1250°C (particularly 850°C to 1200°C, 900°C to 1150°C, 950°C to 1100°C, or 100°C to 1050°C) when the glass is heat treated in a gradient furnace with ramp temperature control for a holding time of 5 minutes. maxis at least 0.1 μm / min, e.g., at least 0.2 μm / min, at least 0.5 μm / min, at least 1.0 μm / min, at least 2.0 μm / min, at least 3.0 μm / min, at least 5.0 μm / min, or at least 7.5 μm / min, in the temperature range of 700°C to 1250°C (particularly 850°C to 1200°C, 900°C to 1150°C, 950°C to 1100°C, or 1000°C to 1050°C), when the glass is heat-treated in a gradient furnace with ramping temperature control for a holding time of 5 minutes. max is in the range of 0 to 25 μm / min, for example in the range of 0.1 to 20 μm / min, 0.5 to 15 μm / min, 1.0 to 12 μm / min, 2.0 to 10 μm / min, 3.0 to 7.5 μm / min, 2.0 to 5.0 μm / min, 1.0 to 4.0 μm / min, 0.5 to 3.0 μm / min, 0.2 to 2.0 μm / min, 0.1 to 1.0 μm / min, or 0 to 0.1 μm / min, in the temperature range of 700°C to 1250°C (particularly 850°C to 1200°C, 900°C to 1150°C, 950°C to 1100°C, or 1000°C to 1050°C), when the glass is heat treated in a gradient furnace with ramping temperature control for a holding time of 5 minutes.

[0162] In some embodiments, the UEG is in the range of 650°C to 1100°C, e.g., 700°C to 1050°C, 750°C to 1000°C, 800°C to 950°C, or 850°C to 900°C, when the glass is heat treated for a 5 minute hold time in a gradient furnace with controlled rising temperature. In some embodiments, the UEG is at least 650°C, e.g., at least 700°C, at least 750°C, at least 800°C, or at least 850°C, when the glass is heat treated for a 5 minute hold time in a gradient furnace with controlled rising temperature. In some embodiments, the UEG is up to 1100°C, e.g., up to 1050°C, up to 1000°C, up to 950°C, or up to 900°C, when the glass is heat treated for a 5 minute hold time in a gradient furnace with controlled rising temperature.

[0163] In some embodiments, the OEG is in the range of 850°C to 1350°C, e.g., 900°C to 1300°C, 950°C to 1250°C, 1000°C to 1200°C, or 1050°C to 1150°C, when the glass is heat treated for a 5 minute hold time in a gradient furnace with controlled rising temperature. In some embodiments, the OEG is at least 850°C, e.g., at least 900°C, at least 950°C, at least 1000°C, or at least 1050°C, when the glass is heat treated for a 5 minute hold time in a gradient furnace with controlled rising temperature. In some embodiments, the OEG is up to 1350°C, e.g., up to 1300°C, up to 1250°C, up to 1200°C, or up to 1150°C, when the glass is heat treated for a 5 minute hold time in a gradient furnace with controlled rising temperature.

[0164] In some embodiments, when the glass is heat treated in a gradient furnace with rising temperature control for a 5 minute hold time, the difference between the OEG and the UEG is in the range of 100-300 K, e.g., in the range of 125-275 K, 150-250 K, or 175-225 K. In some embodiments, when the glass is heat treated in a gradient furnace with rising temperature control for a 5 minute hold time, the difference between the OEG and the UEG is at least 100 K, e.g., at least 125 K, at least 150 K, or at least 175 K. In some embodiments, when the glass is heat treated in a gradient furnace with rising temperature control for a 5 minute hold time, the difference between the OEG and the UEG is at most 300 K, e.g., at most 275 K, at most 250 K, or at most 225 K.

[0165] Due to their excellent resistance to devitrification, the glasses of the invention can be produced by all known glass forming processes, in particular by tube draw processes, such as the Danner process, the Bellow process or the A-draw process (vertical draw process).

[0166] Other characteristics The upper cooling point T13 (English: “annealing point”) is the point where the viscosity is 10 13In some embodiments, the upper cooling point T13 is in the range of 550°C to 750°C, e.g., 575°C to 725°C, 600°C to 700°C, or 625°C to 675°C. In some embodiments, the upper cooling point T13 is at least 550°C, e.g., at least 575°C, at least 600°C, or at least 625°C. In some embodiments, the upper cooling point T13 is at most 750°C, e.g., at most 725°C, at most 700°C, or at most 675°C.

[0167] The softening point T7.6 (in English, "softening point") is when the viscosity is 10 7.6 In some embodiments, the softening point T7.6 is in the range of 700°C to 900°C, e.g., 725°C to 875°C, 750°C to 850°C, or 775°C to 825°C. In some embodiments, the softening point T7.6 is at least 700°C, e.g., at least 725°C, at least 750°C, or at least 775°C. In some embodiments, the softening point T7.6 is at most 900°C, e.g., at most 875°C, at most 850°C, or at most 825°C.

[0168] In some embodiments, the difference between the lower devitrification limit UEG and the softening point T7.6 is in the range of 25-175 K, e.g., in the range of 40-160 K, 50-150 K, 60-140 K, 70-130 K, or 75-125 K. In some embodiments, the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 25 K, e.g., at least 40 K, at least 50 K, at least 60 K, at least 70 K, or at least 75 K. In some embodiments, the difference between the lower devitrification limit UEG and the softening point T7.6 is at most 175 K, e.g., at most 160 K, at most 150 K, at most 140 K, at most 130 K, or at most 125 K.

[0169] The working point T4 (English: “working point”) is where the viscosity is 10 4In some embodiments, treatment point T4 is in the range of 800°C to 1100°C, e.g., 850°C to 1050°C, 875°C to 1025°C, or 900°C to 1000°C. In some embodiments, treatment point T4 is at least 800°C, at least 850°C, at least 875°C, or at least 900°C. In some embodiments, treatment point T4 is at most 1100°C, e.g., at most 1050°C, at most 1025°C, or at most 1000°C.

[0170] In some embodiments, the glass transition temperature Tg is in the range of 525°C to 725°C, e.g., in the range of 550°C to 700°C, 575°C to 675°C, or 600°C to 650°C. In some embodiments, the glass transition temperature Tg is at least 525°C, e.g., at least 550°C, at least 575°C, or at least 600°C. In some embodiments, the glass transition temperature Tg is at most 725°C, e.g., at most 700°C, at most 675°C, or at most 650°C.

[0171] In this disclosure, when the average coefficient of thermal expansion (CTE) is mentioned, it means the average coefficient of linear thermal expansion in the temperature range of 20 to 300°C, unless otherwise specified.

[0172] In some embodiments, the average coefficient of linear thermal expansion is in the range of 5.0 to 9.0 ppm / K, e.g., 5.5 to 8.5 ppm / K, 6.0 to 8.0 ppm / K, between 6.0 and 8.0 ppm / K, or 6.5 to 7.5 ppm / K. In some embodiments, the average coefficient of linear thermal expansion is at least 5.0 ppm / K, e.g., at least 5.5 ppm / K, at least 6.0 ppm / K, greater than 6.0 ppm / K, or at least 6.5 ppm / K. In some embodiments, the average coefficient of linear thermal expansion is at most 9.0 ppm / K, e.g., at most 8.5 ppm / K, at most 8.0 ppm / K, less than 8.0 ppm / K, or at most 7.5 ppm / K.

[0173] In some embodiments, the density of the glass is 4.00 to 4.60 g / cm 3 In the range of, for example, 4.05 to 4.55 g / cm 3 , 4.10~4.50g / cm 3 , 4.15~4.45g / cm 3 , 4.20~4.40g / cm 3 or 4.25 to 4.35 g / cm 3 In some embodiments, the density of the glass is at least 4.00 g / cm 3 and for example at least 4.05 g / cm 3 , at least 4.10 g / cm 3 , at least 4.15 g / cm 3 , at least 4.20 g / cm 3 or at least 4.25 g / cm 3 In some embodiments, the density of the glass is at most 4.60 g / cm 3 and a maximum of 4.55 g / cm 3 , up to 4.5g / cm 3 , up to 4.45g / cm 3 , up to 4.40 g / cm 3 or a maximum of 4.35 g / cm 3 is.

[0174] Glass articles and / or optical waveguide elements The present invention also relates to glass articles, in particular optical waveguide elements, such as glass fibers and / or optical waveguide rods, which comprise or consist of the glasses of the present invention. The optical waveguide elements may in particular be glass fibers having a core glass and a cladding glass. The glasses according to the present invention are in particular used as core glasses.

[0175] In some embodiments, the optical waveguide element comprises at least one core glass and at least one clad glass, e.g., exactly one core glass and at least one clad glass, at least one core glass and exactly one clad glass, or exactly one core glass and exactly one clad glass. In some embodiments, the optical waveguide element consists of at least one core glass and at least one clad glass, e.g., exactly one core glass and at least one clad glass, at least one core glass and exactly one clad glass, or exactly one core glass and exactly one clad glass. The core glass comprises or consists of a glass of the present invention.

[0176] In some embodiments, the optical waveguide element comprises a glass according to the present invention as a core glass and further comprises a cladding glass covering the core glass.

[0177] In some embodiments, the optical waveguide element is a light guide and / or image guide comprising a glass according to the present invention as a core glass, covered with a cladding glass, for example a step-index fiber.

[0178] Optical waveguide elements can be flexible or rigid. Whether a flexible or rigid optical waveguide element is present depends primarily on the diameter of the optical waveguide element. Similarly, optical waveguide elements can exist in the form of glass fibers in fiber bundles containing multiple glass fibers. Such glass fibers and / or fiber bundles are usually flexible, and the diameter of each individual glass fiber is generally from tens to hundreds of micrometers. Glass fibers typically consist of a core-clad system, including a core glass and a clad glass surrounding the outer surface of the core glass. Optical waveguiding is achieved by total internal reflection at the interface between the core and the clad. To achieve total internal reflection, the clad glass usually has a lower refractive index than the core glass.

[0179] Optical waveguide rods are typically rigid because they have relatively large diameters, typically less than a millimeter to a few centimeters. While such optical waveguide rods can be formed as core-clad systems as described above, they can also be formed as glass rods without a cladding glass, in which case total internal reflection occurs at the interface between the outer periphery and the surrounding medium, typically air. A special form of optical waveguide rod also encompassed by the concept and / or the present invention is a fiber rod in which multiple glass elements are sintered or melted together from a core-clad system.

[0180] Glass fibers and / or fiber rods can transmit light and thus function as light guides, as well as image guides, provided that there is a 1:1 correspondence between the positions of the individual fiber cores in the input plane and the positions of the individual fiber cores in the output plane. These concepts are known to those skilled in the art and will not be further described below.

[0181] An important characteristic quantity for forming optical waveguide elements is the difference between the mean linear thermal expansion coefficient of the core glass and the mean linear thermal expansion coefficient of the cladding glass, also referred to as "ΔCTE(core-clad)." Depending on the application of the optical fiber, a positive ΔCTE(core-clad), a zero difference, or a negative difference may occur. For light guides, a ΔCTE(core-clad)≧0 ppm / K is preferred. For image guides, a ΔCTE(core-clad)≧−0.5 ppm / K is preferred.

[0182] In some embodiments, particularly light guides (LLFs), the core glass has a mean linear thermal expansion coefficient greater than that of the cladding glass used. This can improve strength, particularly fiber strength. In some embodiments, the difference between the mean linear thermal expansion coefficient of the core glass and the mean linear thermal expansion coefficient of the cladding glass is in the range of 0 to 5.5 ppm / K, such as 0.1 to 5.0 ppm / K, 0.2 to 4.5 ppm / K, 0.5 to 4.0 ppm / K, 1.0 to 3.5 ppm / K, 1.2 to 3.0 ppm / K, 1.5 to 2.6 ppm / K, or >2.0 to 2.4 ppm / K. In some embodiments, the difference between the average linear thermal expansion coefficient of the core glass and the average linear thermal expansion coefficient of the cladding glass is at least 0.1 ppm / K, e.g., at least 0.2 ppm / K, at least 0.5 ppm / K, at least 1.0 ppm / K, at least 1.2 ppm / K, at least 1.5 ppm / K, or greater than 2.0 ppm / K. In some embodiments, the difference between the average linear thermal expansion coefficient of the core glass and the average linear thermal expansion coefficient of the cladding glass is at most 5.0 ppm / K, e.g., at most 4.5 ppm / K, at most 4.0 ppm / K, at most 3.5 ppm / K, at most 3.0 ppm / K, at most 2.6 ppm / K, or at most 2.4 ppm / K.

[0183] In some embodiments (particularly image guides (LFB)), the difference between the average linear thermal expansion coefficient of the core glass and the average linear thermal expansion coefficient of the cladding glass is in the range of −0.5 to 3.5 ppm / K, such as −0.4 to 3.0 ppm / K, −0.3 to 2.5 ppm / K, 0 to 2.0 ppm / K, or 0.5 to 1.5 ppm / K. In some embodiments, the difference between the average linear thermal expansion coefficient of the core glass and the average linear thermal expansion coefficient of the cladding glass is at least −0.5 ppm / K, such as at least −0.4 ppm / K, at least −0.3 ppm / K, at least −0.2 ppm / K, at least −0.1 ppm / K, at least 0 ppm / K, or at least 0.5 ppm / K. In some embodiments, the difference between the mean linear thermal expansion coefficient of the core glass and the mean linear thermal expansion coefficient of the cladding glass is at most 3.5 ppm / K, e.g., at most 3.0 ppm / K, at most 2.5 ppm / K, at most 2.0 ppm / K, or at most 1.5 ppm / K. In some embodiments, the cladding glass has a mean linear thermal expansion coefficient in the range of 3.5 to 7.0 ppm / K, e.g., at most 4.0 to 6.5 ppm / K or at most 4.5 to 6.0 ppm / K. In some embodiments, the mean linear thermal expansion coefficient of the cladding glass is at least 3.5 ppm / K, e.g., at least 4.0 ppm / K or at least 4.5 ppm / K. In some embodiments, the mean linear thermal expansion coefficient of the cladding glass is at most 7.0 ppm / K, e.g., at most 6.5 ppm / K or at most 6.0 ppm / K.

[0184] The refractive index of the cladding glass is lower than that of the core glass so that light is reflected at the interface between the core and cladding glasses. In some embodiments, the refractive index of the core glass, n d and the refractive index of the cladding glass n d The difference between the refractive index n and the refractive index n of the core glass is in the range of 0.05 to 0.40, for example, in the range of 0.08 to 0.35, 0.10 to 0.30, 0.15 to 0.27, or 0.20 to 0.25. d and the refractive index of the cladding glass n dThe refractive index of the core glass, n d and the refractive index of the cladding glass n d The difference between is at most 0.40, for example at most 0.35, at most 0.30, at most 0.27, at most 0.27 or at most 0.25.

[0185] In some embodiments, the refractive index of the cladding glass, n d is in the range of 1.45 to 1.60, for example in the range of 1.46 to 1.55, 1.47 to 1.54, or 1.48 to 1.52. In some embodiments, the refractive index n d is at least 1.45, such as at least 1.46, at least 1.47, or at least 1.48. In some embodiments, the refractive index n d is at most 1.60, for example at most 1.55, at most 1.54 or at most 1.52.

[0186] In some embodiments, the cladding glass has an SiO2 content of >60 wt%, for example >65 wt% or at least 69 wt%. In some embodiments, the SiO2 content is up to 75 wt%, for example up to 73 wt%. The cladding glass surrounds the glass according to the present invention in the light guide and / or image guide. The glass according to the present invention forms the so-called core glass. Therefore, the cladding glass tends to be more susceptible to environmental influences than the core glass. A higher SiO2 content results in better chemical resistance. Therefore, the content of the component in the cladding glass is preferably higher than that in the core glass.

[0187] The cladding glass, in some embodiments, further comprises at least 5.5 wt. % alkali metal oxides. In some embodiments, the alkali metal oxide content of the cladding glass is at least 7 wt. % and, for example, at least 8 wt. %. The alkali metal oxides include, among others, Na2O, KO, and Li2O.

[0188] The Na2O content in some embodiments is at least 0.5 wt%, e.g., at least 2 wt%. In some embodiments of the cladding glass, at least 6 wt% Na2O is present in the cladding glass. In some embodiments, the Na2O content is at most 15.5 wt%, e.g., at most 15 wt%.

[0189] Li2O is present in the cladding glass in some embodiments at up to 0.7 wt%, such as up to 0.6 wt%, hi some embodiments, the cladding glass is free of Li2O.

[0190] In some embodiments, the K2O content in the cladding glass is at least 2 wt%, e.g., at least 2.5 wt%. In some embodiments, the K2O content is up to 8 wt%, e.g., up to 7.5 wt%. In some embodiments, the glass is free of K2O. In some embodiments, the cladding glass is free of additional alkali metal oxides other than Na2O and K2O.

[0191] In some embodiments, the cladding glass comprises at least 0.5 wt. % of an oxide selected from the group consisting of CaO, MgO, BaO, and ZnO, and mixtures thereof. In some embodiments, the total content of these oxides is at least 0.6 wt. %. In some embodiments, the total content of these oxides is at most 12 wt. % in some embodiments, e.g., at most 11 wt. %, at most 5 wt. %, or at most 2.5 wt. %. In some embodiments, the cladding glass comprises exactly two oxides selected from CaO, MgO, BaO, and ZnO. In some embodiments, the cladding glass comprises only one oxide selected from the group consisting of CaO, MgO, BaO, and ZnO.

[0192] In some embodiments, the cladding glass comprises at least 0.5 wt.% Al2O3, such as at least 1 wt.% or at least 2 wt.% Al2O3, hi some embodiments, the cladding glass comprises at most 7.5 wt.% Al2O3, such as up to 7 wt.%, at most 3 wt.%, or at most 1 wt.% Al2O3.

[0193] The cladding glass may include B2O3, where in some embodiments, the cladding glass includes at least 9 wt% or at least 9.5 wt% B2O3, hi some embodiments, the cladding glass includes up to 19 wt% B2O3, for example, up to 18.5 wt% B2O3.

[0194] In some embodiments, the cladding glass comprises a greater content of the sum of the elements B2O3 and Al2O3 than the core glass.

[0195] In some embodiments, the SiO content in the clad glass is greater than the SiO content in the core glass. Furthermore, in some embodiments, the LaO content in the clad glass is significantly less than the LaO content in the core glass. If the SiO fraction in the core is too high, tuning to higher refractive indices using LaO becomes impossible. Furthermore, in some embodiments, the ZnO content in the clad glass is significantly less than the ZnO content in the core glass. This is because the viscosity of the core glass is preferably lower than that of the clad glass. This improves the fiber tensile properties. In some embodiments, the sum of the ZnO and BaO contents in the clad glass is less than the sum of the ZnO and BaO contents in the core glass.

[0196] The cladding glass may include ZrO2, where in some embodiments, up to 0.04 wt% ZrO2 is present in the cladding glass, or up to 0.03 wt% ZrO2 is present in the cladding glass.

[0197] As2O3 may be included in the cladding glass, for example, in a content of up to 0.05 wt. %, or in a content of up to 0.01 wt. %. Arsenic oxide is responsible for solarization. In some embodiments, the cladding glass is free of As2O3.

[0198] Sb2O3 may be present in the cladding glass, for example, in a content of up to 0.05 wt. %, or in a content of up to 0.01 wt. %. In some embodiments, the cladding glass is free of Sb2O3.

[0199] The cladding glass may further comprise fluorine or fluoride and / or chlorine or chloride. In some embodiments, the fluoride content is up to 0.6 wt. % or up to 0.55 wt. %. Chloride may be present in the cladding glass, for example, at a maximum content of 0.2 wt. % or up to 0.15 wt. %. Some embodiments of the cladding glass are free of fluorine or fluoride and / or chlorine or chloride.

[0200] The following table shows some preferred compositions of cladding glasses that can be used with the glass according to the invention. The cladding glasses contain the following components (in % by weight): [Table 13]

[0201] Those skilled in the art may use further cladding glasses based on their own expertise.

[0202] With the variations on the core glass mentioned above, borosilicate glass as cladding glass has proven to be particularly advantageous for obtaining a robust, i.e., pull-resistant, wide-angle fiber with an advantageous numerical aperture NA of 0.86, corresponding to a 2α opening angle of 120°.

[0203] In some embodiments, the numerical aperture (NA) of the fiber is in the range of 0.40 to 1.30, e.g., 0.45 to 1.20, 0.50 to 1.10, 0.60 to 1.05, 0.70 to 1.00, 0.75 to 0.95, 0.77 to 0.93, or 0.80 to 0.90. In some embodiments, the numerical aperture of the fiber is at least 0.40, e.g., at least 0.45, at least 0.50, at least 0.60, at least 0.70, at least 0.75, at least 0.77, or at least 0.80. In some embodiments, the numerical aperture of the fiber is at most 1.30, e.g., at most 1.20, at most 1.10, at most 1.05, at most 1.00, or at most 0.95, e.g., at most 0.93, or at most 0.90.

[0204] In some embodiments, the fiber opening angle 2α is in the range of 95° to 140°, e.g., in the range of 100° to 135°, 105° to 130°, 110° to 125°, or 115° to 120°. In some embodiments, the fiber opening angle is at least 95°, e.g., at least 100°, at least 105°, at least 110°, or at least 115°. In some embodiments, the fiber opening angle is at most 140°, e.g., at most 135°, at most 130°, at most 125°, or at most 120°.

[0205] Particularly for endoscopic applications with camera chips corresponding to a diagonal viewing angle of approximately 120°, a 2α opening angle of at least 100°, preferably 120°, is particularly advantageous, which corresponds to an NA of 0.86.

[0206] In some embodiments, the fiber has a length in the range of 0.1 to 50 m, e.g., 0.2 to 25 m, 0.5 to 10 m, 1.0 to 5.0 m, 1.0 to 3.0 m, or 1.5 to 2.5 m. In some embodiments, the fiber has a length of at least 0.1 m, e.g., at least 0.2 m, at least 0.5 m, at least 1.0 m, or at least 1.5 m. In some embodiments, the fiber has a length of up to 50 m, e.g., up to 25 m, up to 10 m, up to 5.0 m, up to 3.0 m, or up to 2.5 m. Of course, such fibers can be provided in significantly longer lengths in the fiber drawing process. Therefore, it is quite common to initially produce lengths greater than 50 m, i.e., lengths ranging from several hundred meters to several kilometers, and then refine these to lengths such as those listed above.

[0207] In some embodiments, the fibers have a diameter in the range of 2.0 to 1000 μm, e.g., 3.0 to 750 μm, 4.0 to 500 μm, 10 to 425 μm, 20 to 350 μm, 25 to 150 μm, or 35 to 100 μm. In some embodiments, the fibers have a diameter of at least 2.0 μm, e.g., at least 3.0 μm, at least 4.0 μm, at least 10 μm, at least 20 μm, at least 25 μm, or at least 35 μm. In some embodiments, the fibers have a diameter of at most 1000 μm, e.g., at most 750 μm, at most 500 μm, at most 425 μm, at most 350 μm, at most 150 μm, or at most 100 μm.

[0208] In some embodiments (particularly light guides (LLF)), the fiber has a diameter in the range of 4.0 to 1000 μm, for example, in the range of 10 to 350 μm, 15 to 150 μm, 20 to 100 μm, or 25 to 75 μm. In some embodiments (particularly light guides (LLF)), the fiber has a diameter of at least 4.0 μm, for example, at least 10 μm, at least 15 μm, at least 20 μm, or at least 25 μm. In some embodiments (particularly light guides (LLF)), the fiber has a diameter of at most 1000 μm, for example, at most 350 μm, at most 150 μm, at most 100 μm, or at most 75 μm.

[0209] In some embodiments (especially image guides (LFB)), the fiber has a diameter in the range of 2.0 to 10 μm, for example in the range of 3.0 to 7.0 μm or 4.0 to 6.0 μm. In some embodiments (especially image guides (LFB)), the fiber has a diameter of at least 2.0 μm, for example at least 3.0 μm or at least 4.0 μm. In some embodiments (especially image guides (LFB)), the fiber has a diameter of at most 10 μm, for example at most 7.0 μm or at most 6.0 μm.

[0210] The present invention also relates to a fiber bundle containing one or more fibers according to the invention or consisting of two or more fibers according to the invention.

[0211] In some embodiments, such fiber bundles have lengths in the range of 0.1 to 50 m, e.g., in the range of 0.2 to 25 m, 0.5 to 10 m, 1.0 to 5.0 m, 1.0 to 3.0 m, or 1.5 to 2.5 m. In some embodiments, the fiber bundles have lengths of at least 0.1 m, e.g., at least 0.2 m, at least 0.5 m, at least 1.0 m, or at least 1.5 m. In some embodiments, the fiber bundles have lengths of up to 50 m, e.g., up to 25 m, up to 10 m, up to 5.0 m, up to 3.0 m, or up to 2.5 m.

[0212] In some embodiments (particularly image guides, e.g., LFBs), the fiber bundle has 100-50,000 fibers, e.g., 200-40,000 fibers, 500-25,000 fibers, 1,000-15,000 fibers, or 3,000-10,000 fibers. In some embodiments (particularly image guides, e.g., LFBs), the fiber bundle has at least 100 fibers, e.g., at least 200, at least 500, at least 1,000, at least 3,000, at least 5,000, at least 7,500, or at least 10,000 fibers. In some embodiments (particularly image guides, e.g., LFBs), the fiber bundle has up to 100,000 fibers, e.g., up to 50,000, up to 40,000, up to 25,000, up to 15,000, or up to 10,000 fibers.

[0213] In some embodiments (particularly light guides (LLF)), the fiber bundle has between 3 and 1000 fibers, e.g., between 5 and 750, 10 and 500, 20 and 200, or 50 and 100 fibers. In some embodiments (particularly light guides (LLF)), the fiber bundle has at least 3 fibers, e.g., at least 5, at least 10, at least 20, or at least 50 fibers. In some embodiments (particularly light guides (LLF)), the fiber bundle has up to 1000 fibers, e.g., up to 750, up to 500, up to 200, or up to 100 fibers.

[0214] Manufacturing method The present invention also relates to a method for producing a glass or optical waveguide element according to the invention, said method in particular comprising the following steps: - melting the glass frit, - cooling the glass obtained to obtain the glass or optical waveguide element of the present invention. Includes.

[0215] In some embodiments, the method includes fining the glass melt. In some embodiments, the fining temperature is in the range of 1150°C to 1650°C, e.g., 1200°C to 1600°C, 1225°C to 1550°C, 1250°C to 1500°C, 1275°C to 1450°C, 1300°C to 1400°C, or 1320°C to 1300°C. In some embodiments, the fining temperature is at least 1150°C, e.g., at least 1200°C, at least 1225°C, at least 1250°C, at least 1275°C, at least 1300°C, or at least 1320°C. In some embodiments, the fining temperature is at most 1650°C, e.g., at most 1600°C, at most 1550°C, at most 1500°C, at most 1450°C, at most 1400°C, or at most 1360°C.

[0216] The glass mixture can be melted and / or refined by radio frequency (HF) heating. However, it is also possible to melt and refine the mixture without radio frequency heating. A particular advantage of the glass of the present invention is that its production can be achieved without laborious radio frequency heating. Omission of radio frequency heating is also advantageous because, under conditions where the Nb and Ti contents are increased, HF-fined glass turns brown or yellow / green. If the glass contains Fe as an impurity, HF fining leads to an increase in the Fe(II) content, which absorbs in the near infrared (NIR).

[0217] "High frequency heating" is understood to mean a method of heating the mixture to be heated by inductive coupling of an alternating electromagnetic field. The alternating electromagnetic field has a frequency of, for example, at least 50 kHz or at least 100 kHz. The frequency is, for example, at most 5 MHz, at most 3 MHz, or at most 1 MHz. The electromagnetic field generates an alternating current in the electrically conductive glass melt, which causes direct heating of the melt due to Joule heating.

[0218] The step of cooling can include active cooling, passive cooling, or a mixture of the two.

[0219] In some embodiments, the method includes processing the glass melt using a downdraw, overflow fusion, floating or tube draw process, in particular the Danner, Bellow or A-draw (vertical draw) process.

[0220] In some embodiments, the method includes processing an optical waveguide element using a fiber draw process or redrawing a glass fiber or optical fiber to form a lens preform or container. In some embodiments, the method includes processing a glass article using a fiber draw process to form a glass fiber.

[0221] use The present invention also relates to the use of the glass or glass article according to the invention as a fiber glass. The present invention also relates to the use of the glass or optical waveguiding element according to the invention in or as a glass fiber. The present invention further relates to the use of the glass according to the invention as a core glass, in particular as a core glass in a light guide and / or image guide. The present invention further relates to the use of the glass or glass article according to the invention as or in a light guide and / or image guide.

[0222] The invention also relates to the use of glasses or glass articles according to the invention for the fields of imaging, projection, communication, optical messaging technology, mobile drives, laser technology and disinfection, as well as optical elements or preforms (so-called "preforms") of such optical elements.

[0223] Particularly advantageous is the use in endoscopy systems for one-way or single-use endoscopy in industrial and / or medical technology, in particular in the medical field.

[0224] Exemplary Configurations Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 14] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, and the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm.

[0225] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 15] wherein the glass comprises at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at least 0.01, and the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled temperature rise and a holding time of 5 minutes.

[0226] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 16] Here, the glass comprises at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at least 0.01, and the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50K.

[0227] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 17] where the glass contains at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0228] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 18] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, and the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled temperature rise and a holding time of 5 minutes.

[0229] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 19] wherein the glass comprises at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, and the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50 K.

[0230] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 20] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0231] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 21] wherein the glass comprises at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at least 0.01, and when the glass is heat treated in a gradient furnace with controlled temperature rise and a holding time of 5 minutes, the lower devitrification limit UEG is at least 650°C, and the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50K.

[0232] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 22] wherein the glass comprises at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at least 0.01, the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled temperature rise and a holding time of 5 minutes, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0233] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 23] where the glass contains at least one of the two components Gd2O3 and Y2O3, the ratio of the sum of the weight fractions of Gd2O3 and Y2O3 to the weight fraction of SiO2 is at least 0.01, the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50 K, and the refractive index of the glass n d is in the range of 1.65 to 1.80.

[0234] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 24] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled temperature rise and a holding time of 5 minutes, and the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50K.

[0235] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 25] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled temperature rise for a holding time of 5 minutes, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0236] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 26] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50 K, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0237] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 27] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, when the glass is heat treated in a gradient furnace with controlled temperature rise and a holding time of 5 minutes, the lower devitrification limit UEG is at least 650°C, the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50K, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0238] Some preferred embodiments relate to glass or glass articles comprising the following components in the stated proportions [wt %]: [Table 28] wherein the glass comprises at least one of two components Gd2O3 and Y2O3, the ratio of the sum of the weight percentages of Gd2O3 and Y2O3 to the weight percentage of SiO2 is at least 0.01, the glass has a net transmittance of at least 0.900 at a sample thickness of 25 mm and a wavelength of 380 nm, the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled temperature rise for a holding time of 5 minutes, the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50K, and the refractive index of the glass, n d is in the range of 1.65 to 1.80.

[0239] As mentioned above, it is particularly advantageous if both Gd2O3 and Y2O3 are present in the glass according to the invention.

[0240] example 1. Exemplary Glasses and Their Properties The following table shows the composite compositions and properties of selected glasses. The percentages of the individual components are shown as a percentage of the composite composition in weight percent. These are each normalized to 100% and are shown rounded to a decimal point, excluding fining agents. Deviations from 100% are due to rounding. The net transmittances Ti at 380 nm and 600 nm are shown, rounded to three decimal places, for a sample thickness of 25 mm. Each example was produced under laboratory conditions and therefore suffers from reduced internal quality. Under production conditions, the glass compositions of the present invention achieve even higher net transmittances than those of the present examples.

[0241] [Table 29]

[0242] As shown in the table, the examples and comparative examples have refractive indices n d , Abbe number v d The CTE, density, mean coefficient of thermal expansion (CTE) and glass transition temperature (Tg) in the temperature range from 20°C to 300°C are almost identical. The CTE, density and Tg were measured on samples cooled at a cooling rate of 120 K / h before the measurements. The refractive index n d and Abbe number v d was measured on samples that had been cooled at a cooling rate of 30 K / h before the measurement. If such samples are cooled again before the measurement, this cooling is generally done from a temperature above the Tg of the glass (about 100 K) but below the softening temperature.

[0243] The following table shows the synthetic compositions and properties of other exemplary glasses.

[0244] [Table 30]

[0245] The following table shows the synthetic compositions and properties of other exemplary glasses.

[0246] [Table 31]

[0247] Depending on the melting conditions, the transmittance values ​​may vary slightly even for the same composition. A decrease in transmittance can be observed, for example, in melts containing or in Pt. This is especially true for small volumes of melts, such as laboratory melts.

[0248] The following table shows the analytical composition [wt. %] of selected glasses. The composition analysis was carried out by X-ray Fluorescence Spectroscopy (XRF).

[0249] [Table 32]

[0250] The following table shows further properties of Examples 12 to 14.

[0251] [Table 33] The upper cooling point T13 (English: “annealing point”) is the point where the viscosity is 10 13 The softening point T7.6 is the temperature at which the viscosity becomes 10 7.6 The treatment point T4 is the temperature at which the viscosity reaches 10 4 This is the temperature at which the viscosity becomes dPa·s.

[0252] 2. Crystallization resistance The crystallization resistance of the glasses of Examples 12 to 14 was tested.

[0253] Crystallization rates were determined by heat treating the glasses in a gradient furnace with ramped temperature control over holding times of 5 or 60 minutes. Crystallization rates were determined using glass powders ranging in diameter from 1.6 mm to 4 mm. The glass powders were placed on platinum supports for heat treatment in the gradient furnace. Each support had a recess to accommodate a glass core. Holes in the underside of each recess allowed the crystallization rate to be determined microscopically following heat treatment. The maximum observed crystallization rate was the maximum crystallization rate (KG). max The UEG and OEG were determined as the lower and upper limits of the temperature region where crystallization occurred.

[0254] The results are summarized in the following table: [Table 34] At a retention time of 60 minutes, the UEG was not determinable (nb).

[0255] 3. Cladding glass and core glass Borosilicate glasses are particularly suitable as cladding glasses to be combined with the glasses described herein. Borosilicate glasses are generally glasses containing SiO2 and B2O3. Borosilicate glasses in particular contain (by weight) 60-75% SiO2, 7-25% B2O3, and 5-17% Al2O3. In particular, further components such as alkalis may also be present.

[0256] Variations of borosilicate glasses, which may have, for example, a lower content of B2O3, are possible as well. Advantageous in combination with the glasses described herein are components in the range of compositions listed in the following table, which may be included as cladding glasses, especially for the glasses described as core glasses [% by weight]: [Table 35]

[0257] Other optional components are of course also possible, such as in particular MgO and / or TiO2 and / or CaO.

[0258] The following table lists, as further examples, two clad glasses having respective compositions (analyzed in wt % on an oxide basis), which are essentially included in group B2 of the table above. d means the refractive index, CTE means the average coefficient of linear thermal expansion in the range of 20℃ to 300℃, and the softening point T7.6 means the viscosity of 10 7.6 where S means temperature in dPa·s, S means acid resistance (weight loss after acid attack to classify glasses into acid classes), and L means alkali resistance (resistance of glass to aqueous mixed solutions at their boiling point).

[0259] [Table 36]

[0260] Based on the difference in refractive index between the core glass and the cladding glass, the numerical aperture (NA) and opening angle of the optical fiber light guide (light guide fiber) can be calculated. The following table summarizes the results of combining the glasses of the present invention as the core glass (see Examples 1-4 and 6-15 above) with cladding glasses I and II. The expression "ΔCTE" represents the difference between the CTE of the core glass and the CTE of the cladding glass.

[0261] [Table 37]

[0262] The invention will now be explained with reference to the drawings, which also constitute exemplary embodiments. [Brief explanation of the drawings]

[0263] [Figure 1] 1 is a schematic diagram showing a glass fiber. [Figure 2]1 is a first characteristic graph showing the spectral attenuation of a glass fiber according to the present invention compared to a conventional glass fiber. [Figure 3] 10 is a second characteristic graph showing the measured intensity as a function of the angle relative to the radial axis of the glass fiber to determine the opening angle.

[0264] 1 shows a schematic representation of a glass fiber formed as an optical waveguide element 1, the glass fiber having a core glass 2 and a cladding glass 3. The fiber thus produced has an overall diameter of 70 μm. In the example shown, the glass of Example 15 above is used as the core glass 2.

[0265] The cladding glass 3 is made of the above-mentioned borosilicate glass, particularly having a composition containing components of group B1 or B2, and is typically formed as a glass tube.

[0266] 2 shows the results of a spectral attenuation measurement for a conventional glass fiber 7 and a glass fiber 8 according to the invention, as described above in FIG. 1 in a first characteristic graph 4. Here, the spectral attenuation 5 is recorded in nanometers as a function of the wavelength 6 of the transmitted light. For this purpose, so-called measurement light guides having a specific length, for example, 1 m or 3 m, are manufactured, and the transmittance is measured, taking into account the reflection losses at the end faces. From the transmittance and length of the waveguide, the length-independent spectral attenuation, shown in the graph in [dB / km], can then be calculated, from which the more conventional dB / m expression 1000 dB / km = 1 dB / m can be derived for the waveguide in question.

[0267] In this case, it is particularly advantageous that the spectral attenuation 5 of the glass fiber 7 according to the invention is lower in the near-infrared (NIR) region, for example, at a wavelength 6 of 800 nm, than, for example, a conventional glass fiber 8, as described above. This corresponds to 200 dB / km or 0.2 dB / m in the illustrated example, compared with approximately 350 dB / km or 0.35 dB / m for conventional glass fibers. This is particularly advantageous in spectroscopic examinations in medical technology applications, such as endoscopy, because it allows for improved signal-to-noise ratios in tissue analysis, especially in the NIR region, which in turn allows for, for example, higher contrast in imaging. Furthermore, it has been found that in this wavelength region, possible variations in the melting point are less pronounced than in conventional glass fibers, which is why the composition according to the invention is particularly described.

[0268] On the other hand, the first characteristic graph 4 also shows that the so-called UV or blue edge of the glass fiber 8 according to the invention described above is shifted even further towards higher wavelengths than in the case of the conventional glass fiber 7, i.e. the spectral attenuation 5 in the blue wavelength range of 400 nm to 500 nm is significantly higher than in the conventional glass fiber 7. The position of the UV or blue edge can be adjusted by the Y2O3 content or the Gd2O3 content or a combination thereof, as described above.

[0269] The somewhat larger spectral attenuation 5 in the "blue" range does not have any adverse effects, especially when the glass fiber is used in endoscopic instruments, where the typical lengths are 1 m to 2 m at most, so that the so-called "yellow shift" or color shift to yellow occurs rather little, which is especially true for typical lengths < 1 m. It is not critical for single-use endoscopes. Advantageously, a slightly greater attenuation in the blue may be utilized if the light-guiding element, e.g., a glass fiber, is coupled to a light source that emits more strongly in the blue and / or if tissue that is sensitive to blue light and therefore reacts to the higher energy components of the spectrum is to be examined.

[0270] 3 shows a second characteristic graph 9 illustrating the results of determining the opening angle of a glass fiber. For this purpose, the intensity 10 of the light emitted from the light guide is measured as a function of the angle 11 relative to the radiation axis of the light guide, as shown for a conventional glass fiber 7 and for the glass fiber according to the invention 8 according to the glass fiber described above with reference to FIG. 1, using a sensor. The so-called 2α opening angle is then obtained, as defined, from the angle 11 at which the intensity 10 drops to 50% of its maximum value at 0°.

[0271] As shown in FIG. 3, the two glass fibers 7.8 have approximately the same opening angle of 2α=2×approximately 60°=120°, which corresponds to a numerical aperture NA=0.86, where NA=sin -1 (α) applies, and therefore the two glass fibers are referred to as wide-angle glass fibers that can be advantageously used in endoscopic applications, allowing shadow-free illumination of the field of view of such a camera, depending on the diagonal opening angle of the camera chip.

[0272] Another test of the glass fiber 8 according to the present invention, compared to the conventional glass fiber 7, both of which are wide-angle fibers but have a fiber diameter of 70 μm, concerns its strength level. For this purpose, 30 glass fiber samples of the same length were each stretched in a tensile tester, and the stress until the fiber broke was measured. Here, the two glass fibers 7 and 8 were measured to have approximately the same tensile strength near the breaking stress of 1000 MPa. Note that the statistical variation regions overlap so that the same tensile strength level is the basis. [Explanation of symbols]

[0273] 1 Glass articles, optical waveguide elements 2 Core Glass 3. Clad glass 4. First characteristic graph 5 Spectral attenuation 6 wavelengths 7 Conventional glass fiber 8 Optical waveguide element and glass fiber according to the present invention 9 Second characteristic graph 10 strength 11 angles

Claims

1. SiO ２ and two components Gd ２ O ３ and Y ２ O ３ and at least one of: SiO ２ Weight ratio of Gd ２ O ３ and Y ２ O ３ the ratio of the sum of the weight proportions of is at least 0.01, Ta ２ O ５ is at most 10% by weight, ZrO ２ the proportion of is at least 0.1% by weight, preferably 0.1 to 10% by weight, SiO ２ B relative to the weight ratio of ２ O ３ The weight ratio of Glass.

2. Gd ２ O ３ and Y ２ O ３ 2. The glass of claim 1, wherein the sum of the weight percentages of is at least 0.2% by weight.

3. BaO and La ２ O ３ 3. The glass according to claim 1, wherein the sum of the proportions of is at least 20% by weight.

4. The following components in the stated proportions [% by weight]: Table 1 4. The glass according to claim 1, comprising:

5. Y ２ O ３ and Gd ２ O ３ 5. The glass according to claim 1, wherein the proportion of each of the following is at least 0.1% by weight, preferably at least 0.2% by weight:

6. Y ２ O ３ The weight ratio of Nb ２ O ５ 6. The glass according to claim 1, wherein the weight percentage of .theta.

7. La ２ O ３ 7. The glass according to claim 1, wherein the proportion of ##STR1## is at least 15% by weight, preferably at least 16% by weight, particularly preferably at least 17% by weight.

8. La ２ O ３ 8. The glass according to claim 7, wherein the proportion of .alpha.-hydroxybenzoates is at most 40% by weight, preferably at most 38% by weight, particularly preferably at most 37% by weight.

9. Gd ２ O ３ and Y ２ O ３ La relative to the total weight ratio of ２ O ３ 9. The glass according to claim 1, wherein the ratio of the weight percentages of

10. La ２ O ３ , Gd ２ O ３ and Y ２ O ３ 10. The glass according to claim 1, wherein the sum of the proportions of is at least 10% by weight.

11. 11. The glass of claim 1, wherein the lower devitrification limit UEG is at least 650°C when the glass is heat treated in a gradient furnace with controlled rising temperature for a holding time of 5 minutes.

12. 12. The glass according to claim 1, wherein the difference between the lower devitrification limit UEG and the softening point T7.6 is at least 50K.

13. An optical waveguide element (1), in particular a glass fiber or an optical waveguide rod, comprising or consisting of a glass according to at least one of claims 1 to 12, The refractive index n of the glass ｄ is in the range of 1.65 to 1.80, Optical waveguide element (1).

14. 14. The optical waveguide element (1) according to claim 13, wherein the optical waveguide element (1) comprises a glass according to at least one of claims 1 to 12 as a core glass (2) and a cladding glass (3) covering the core glass (2).

15. 15. The optical waveguide element (1) according to claim 14, wherein the cladding glass (3) consists of borosilicate glass.

16. The cladding glass (2) comprises the following components of composition B1 or B2: Table 2 15. The optical waveguide element (1) according to claim 14, comprising:

17. 17. The light guide element (1) according to at least one of claims 13 to 16, wherein the light guide element (1) has a numerical aperture (NA) of at least 0.82, preferably at least 0.

85.

18. 18. The light guide element (1) according to at least one of claims 13 to 17, wherein the light guide element (1) has a spectral attenuation of at most 0.3 dB / m, preferably at most 0.2 dB / m, in the near infrared range at a wavelength (6) of 800 nm.

19. A method for producing a glass according to at least one of claims 1 to 12 or an optical waveguiding element (1) according to at least one of claims 13 to 18, comprising the following steps: - melting the glass frit, - cooling the resulting glass or glass article, - processing the glass melt, in particular using the downdraw, overflow fusion, floating or tube draw process, in particular the Danner, Bellow or A-draw (vertical draw) process; A method comprising:

20. 13. Use of a glass according to at least one of claims 1 to 12 as core glass (2) in a light guide and / or image guide.

21. 20. Use of an optical wave-guiding element (1) according to at least one of claims 13 to 18 in endoscopic applications, in particular in endoscopes, preferably single-use endoscopes, projection devices, optical messaging technology, automotive applications, laser technology and disinfection.

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