Optical glass with high refractive index

Abstract

To provide an optical glass which has a high refractive index: a liquidus temperature which is as low as possible; and, advantageously, an internal transmission which is as high as possible; and a relatively high Abbe number.SOLUTION: There is provided an optical glass which has a refractive index nd of more than 2.10 and includes at least TiO2, NbO2.5, and LaO1.5. The optical glass has the following features: a cation characteristic value K of 1.8<K≤2.8, wherein K satisfies K=(Tiequivalents+SiO2+(BO1.5) / 2) / (Laequivalents), the molar fractions of Tiequivalents, SiO2, BO1.5 and Laequivalents are entered into the cation characteristic value K in cat %; a sum total of glass components SiO2 and B2O3 is 8.0 mol%≤(SiO2+B2O3)≤20.0 mol%; the proportion of B2O3 is more than 0 mol % and the proportion of SiO2 is more than 0 mol%; and a temperature Tmax is temperature Tmax≤1330°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to optical glass, glass articles, and their use. [Background technology]

[0002] The present invention relates to glass that can be used in the field of optical components and lenses, as well as meta-optical components, and in "augmented reality." The latter is understood to be the augmentation of reality, particularly with respect to computer-generated information presented visually. Augmented reality is realized through special AR glasses, each having an optical structural member containing one to three planar waveguides made of glass. On these waveguides, a grating for one wavelength each in the red, green, and optionally blue regions of the visible spectrum is incorporated. Through this, a virtual image or information is coupled and extracted in the waveguide and visualized before the eye. A high refractive index value of the glass substrate acting as a waveguide has the advantage of enabling a wide field of view (FoV). In this case, the FoV is determined through the minimum refractive index value in the system, that is, through the refractive index value of the glass in the red spectrum region. Therefore, a high refractive index value at 587.6 nm n d Furthermore, glasses with a relatively large Abbe number and consequently a small dispersion are preferred. Meta-optical components are understood as nano-optical components whose structural size is significantly smaller than the wavelength of light, for example, one-fifth or one-tenth.

[0003] Heavier glass components, i.e., components with high molar mass, contribute to increasing the refractive index (also called the refractive index), but at the same time increase the density of the glass, which is undesirable. In such cases, the density of the glass often increases disproportionately with the increase in refractive index. This means that even if the glass substrate can be made thinner for AR applications, the glass substrate becomes significantly heavier, which makes prolonged wear of AR glasses uncomfortable. There is a trend towards moving from headsets to standard glasses, which are worn for longer periods or constantly like regular glasses, so the glasses need to be lighter. This weight reduction is also beneficial for many other application areas, because camera optical components in the DSLR field are very often very bulky or very heavy, which significantly increases the power demands of autofocus batteries.

[0004] Furthermore, high refractive index glass is preferable, having particularly good internal transmittance τ in the visible wavelength region. i It should have (internal transmission). In this regard, especially in the case of high refractive index glass, internal transmittance in the lower visible wavelength region, for example, in the blue region of 420 nm to 490 nm, particularly at 420 nm, 450 nm, or 460 nm, has become a problem. In this regard, the so-called "UV edge" of the glass, that is, the decrease in the transmittance curve from the visible region to the UV region of the spectrum, is often explained. If the UV edge shifts too broadly into the visible region or does not rise steeply enough, the transmittance characteristics are not sufficiently good in the lower visible wavelength region depending on the application, and the glass often has a yellowish tint. Furthermore, it has been found that it is difficult to provide glass with a particularly high refractive index across the entire visible region (especially 380 nm to 800 nm).

[0005] A further problem with high refractive index glass is that such glass has a high liquidus temperature, that is, the temperature at which the molten material is in equilibrium with the solid or crystalline material. Below the liquidus temperature, crystals precipitate from the molten material. Because high refractive index glass has a low proportion of glass-forming agent and very low viscosity, below the liquidus temperature in such glass results in very rapid crystal formation because there is little to no dynamic inhibition of crystallization due to the "viscosity" of the molten material. Therefore, a high melting temperature is accompanied by a high liquidus temperature. A high liquidus temperature is even more disadvantageous because, at high temperatures, the problem of intrusion of heat-resistant materials (especially platinum in molten form and as particles) can arise. Furthermore, high temperatures can result in the partial reduction of glass components of multiple valencies (particularly niobium and titanium), each existing at a lower oxidation state, which can lead to problems of glass coloration and reduced transmittance. Low internal transmittance distorts the color perception of projected images, both in AR glasses and other optical structural components. Furthermore, high liquidus temperatures increase the manufacturing cost of high-refractive-index glass.

[0006] Some conventional glasses are derived from niobium phosphate or titanium phosphate systems, and therefore contain large proportions of P2O5 and niobium and / or titanium. These glasses, especially niobium phosphate glass, have a refractive index of less than 2.1 and can be very problematic in production because, in phosphate systems which already act as reducers, oxygen loss due to excessively high melting and clarification temperatures, for example, results in a lower oxidation state. In the case of niobium, this is an oxidation state of less than V, and in the case of titanium, it is an oxidation state of less than IV. This can result in a dark brown to black coloration in niobium systems, or a yellowish-greenish-blue to brown coloration in titanium systems. Furthermore, titanium in titanium phosphate systems significantly increases the crystallization tendency, which is a known problem with existing high refractive index glasses in the heavy flint field, in which case, for example, they are no longer repressable. In contrast to niobium, even titanium with the highest oxidation state is absorbed at the edge of the visible region (towards the UV region), which, at high concentrations, causes the known yellowing of barium titanium silicate.

[0007] Furthermore, niobium phosphate glasses, such as high-refractive index heavy flints or lanthanum heavy flints, not only tend to crystallize at the interface but also exhibit very rapid crystal growth, which can make subsequent cooling (stress cooling or refractive index adjustment) critical for the pre-nucleated glass. Moreover, these glasses are relatively brittle and therefore difficult to polish into very thin wafers.

[0008] German Patent Application Publication No. 102006030867 (DE102006030867 A1) specifies a refractive index n of 2000 or more. d Optical glass having a high barium oxide content is described. The glass disclosed herein has a high barium oxide content, which adversely affects glass formation and refractive index.

[0009] U.S. Patent Application Publication 20160194237 (US20160194237 A1) describes optical glass containing silicon, boron, lanthanum, titanium, niobium, and zirconium, but it typically has a refractive index of less than 2.10. European Patent Application Publication 3845503 (EP3845503 A1), Japanese Patent Application Publication 2020-59629 (JP202059629 A1), and International Publication 2021085271 (WO2021085271 A1) also disclose only glass with a refractive index of less than 2.10, usually less than 2.05. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] German Patent Application Publication No. 102006030867 [Patent Document 2] U.S. Patent Application Publication No. 20160194237 [Patent Document 3] European Patent Application Publication No. 3845503 [Patent Document 4] Japanese Patent Publication No. 2020-59629 Specification [Patent Document 5] International Publication No. 2021085271 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The object of the present invention is to provide optical glass that overcomes the shortcomings of the prior art. Furthermore, the object of the present invention is to provide optical glass with a high refractive index n d The objective is to provide a glass that has the lowest possible liquidus temperature, and preferably the highest possible internal transmittance, and a relatively high Abbe number. The glass should preferably have the lowest possible density, be easily hot-formable, and be easily processable. The above problems are solved by the scope of the claims. [Means for solving the problem]

[0012] Description of the Invention In one aspect, the present invention relates to an optical glass having a refractive index n greater than 2.10 d and containing at least TiO2, NbO 2.5 and LaO 1.5 and having the following characteristics: · Cation characteristic value K, 1.8 < K ≤ 28, where K = (Ti 等価物 + SiO2 + (BO 1.5 ) / 2) / (La 等価物 ), and the molar ratios of Ti 等価物 , SiO2, BO 1.5 and La 等価物 are put into the cation characteristic value K in cation %, · Total of glass components SiO2 and B2O3, 8.0 mol% ≤ (SiO2 + B2O3) ≤ 20.0 mol%, where the proportion of B2O3 is greater than 0 mol% and the proportion of SiO2 is greater than 0 mol%, · Temperature T max ≤ 1330 °C relating to said glass.

[0013] The present invention is mostly based on the precise adjustment of the molar ratios of the cations of the glass components to each other. Therefore, it is reasonable to characterize the glass composition by description in cation %. Of course, the glass also contains anions, especially oxygen. However, the characteristics of the glass according to the present invention are not much determined by anions, so the essence of the present invention lies in the cation composition.

[0014] The term "cation percentage" (abbreviated as "cation %)" refers to the relative molar proportion of cations to the total cation content in glass. Naturally, glass also contains anions, and its relative molar proportion to the total anion content in glass is expressed as anion percentage (anion %). Within the scope of this invention, cations are described at their highest oxidation state and are represented in charge equilibrium with oxygen as anion. However, this does not mean that cations in glass must exist only at their highest oxidation state. For example, in the case of arsenic and antimony, cations may coexist in glass at both trivalent and pentavalent oxidation states. For clarity, the elemental names of the components, such as "niobium," are also used in descriptions of glass composition. This is a substitute for, for example, "niobium cations," and therefore does not mean that elemental niobium is present in the glass.

[0015] In addition to cations, the glass according to the present invention also has anions, which are preferably O 2- F - , Br - Cl - Selected from the group consisting of O 2- The molar proportion of should be at least 50% (anion%), more preferably at least 70%, and more preferably at least 90%, and especially preferably at least 99% with respect to anions. In a preferred embodiment, the glass is O as an anion. 2- It contains only that anion and does not contain any other anions.

[0016] Some compositional characteristics can be better described by stating the molar proportions of the oxide glass components. In such cases, each glass component, or the sum of the glass components, is explicitly stated in mole percent. The description in mole percent can be calculated from the glass composition described in cation percent.

[0017] Within the scope of the present invention, glass systems containing a large amount of TiO2 and having SiO2 are different from the niobium phosphate or titanium phosphate glasses described at the beginning, and are stable with respect to the achievable internal transmittance, have a higher refractive index value, and yet have a relatively low density. As the refractive index value increases, the tendency to devitrify increases. Nevertheless, n d Glasses according to the invention having n>2.10 have been found to have a stable devitrification similar to known titanium, niobium and lanthanum-containing glasses.

[0018] The optical glasses according to the invention have a special ratio of the proportions (cation%) of specific cations of the glass components, which is indicated as the cation characteristic value K and is determined as follows: K = (Ti 等価物 + SiO2+(BO 1.5 ) / 2) / (La 等価物 )

[0019] For the glasses according to the invention, 1.8 < K ≤ 2.8 applies.

[0020] This condition defines a composition range in which, for components advantageous for achieving a high refractive index value and a high internal transmittance, an amorphous glass can be formed, i.e., no crystal phase is formed. In such high refractive index glass systems, it is a problem to obtain a stable glass range at a low liquidus temperature. Through the conditions according to the invention, such a composition range is found and can be explained in the same way as the miscibility gap in the case of binary or ternary systems.

[0021] [[ID=2,6]]At that time, the glass further has a temperature point T max ≤ 1330 °C and n d > 2.10.

[0022] In terms of cation property value K, the cations of the glass composition are classified into various groups according to their crystal ionic radius (for example, RDShannon; Revised Effective Ionic Radii and Systematic Study of Inter Atomic Distances; Halides and Chalcogenides; Acta crystallographica. Section A, 32, 751, 1976): Titanium equivalent (Ti 等価物 ) are titanium (TiO2), niobium (NbO2) 2.5 ), zirconium (ZrO2), tungsten (WO3), tantalum (TaO3) 2.5 ), aluminum (AlO 1.5 ), antimony (SbO 2.5 ) and arsenic (AsO 2.5 It consists of the total molar proportion of cations, that is, ions with a small ionic radius of less than 100 pm.

[0023] Lanthanum equivalent (La 等価物 ) is a lantern (LaO 1.5 ), gadolinium (GdO 1.5 ), Yttrium (YO 1.5 ) and ytterbium (YbO 1.5 It is formed from the cations of ) that is, the total molar proportion of ions having a large ionic radius greater than 100 pm. 等価物 This is the divisor of the cation characteristic value.

[0024] Silicon (SiO2) and boron (BO2) are glass-forming agents. 1.5 The cation percentages in moles of titanium are also included in the above conditions, and these are added to the proportion of cation percentages of titanium equivalent. 等価物 Together with it, it constitutes the dividend of the cation characteristic value. In glass composition, considering the amount of substance, SiO2 can be replaced by B2O3, and in that case the refractive index remains at almost the same level, so BO 1.5 Only half of the cation percentage, i.e. (BO 1.5 ) / 2 fits the above condition.

[0025] By selecting and mixing cations of various sizes in specific ratios according to the present invention, crystal formation can be effectively suppressed.

[0026] According to the present invention, the cation characteristic value K is greater than 1.8 and is at most 2.8. If the cation characteristic value is 1.8 or less, T max If K becomes too high, the internal transmittance decreases due to the intrusion of heat-resistant materials caused by the high temperatures required during the process and the increased reduction of oxides with multiple valencies. Furthermore, as K decreases, the refractive index tends to decrease because lanthanum equivalents do not increase the refractive index as strongly as titanium equivalents. However, the cationic properties should not be too high either. If K is greater than 2.8, there is too little lanthanum equivalent contained in the glass, which affects the crystallization tendency and, consequently, T max This has an adverse effect. Furthermore, if the cationic property value K is too high, and consequently if there is too much titanium equivalent, the glass will contain oxides of multiple valencies, such as TiO2 and NbO 2.5 Based on the higher proportion of [unclear], the tendency to reduce and consequently discolor is stronger. The advantageous lower limit of the cationic property value can be at least 1.9 or above, or at least 2.0. Particularly advantageous embodiments have a lower limit for cationic property values ​​above 2.0, or at least 2.1 or above, or at least 2.2 or above, or at least 2.25 or above, or at least 2.3 or above. Some advantageous variations of the present invention may have an upper limit of cationic property value K of up to 2.75 or below, or up to 2.7 or below, or for some preferred variations, up to 2.6 or below.

[0027] Furthermore, in the case of the glass according to the present invention, the total of the glass components SiO2 and B2O3 is at least 8.0 mol% and at most 20.0 mol%, where the proportion of B2O3 is greater than 0 mol% and the proportion of SiO2 is greater than 0 mol%. The proportions of the glass components SiO2 and B2O3 in mol% based on oxides can each be calculated from the composition described in cation %. The glass according to the present invention requires a total of at least 8.0 mol%, preferably more than 8.0 mol%, preferably at least 9.0 mol%, or at least 10.0 mol%, of (SiO2 + B2O3) so that a glassy composition can be formed in the melting process. However, the total should not exceed the condition of 20.0 mol%, because otherwise the proportion of glass components that increase the refractive index contained in the glass would be too small, resulting in a refractive index that is too low. A favorable upper limit for the total of SiO2 + B2O3 can be <20.0 mol%. In particularly advantageous embodiments, the upper limit of the total SiO2 + B2O3 can be up to 19.0 mol%, or up to 18.0 mol%. Some advantageous variants may also have an upper limit of the total to 17.0 mol%, or up to 16.5 mol%. B2O3 can be advantageously at least 1.0 mol%, or at least 1.5 mol%, or at least 2.0 mol%, and / or advantageously up to 19.0 mol%, or up to 17.0 mol%, or up to 15.0 mol%, or up to 13.0 mol%, or up to 12.0 mol%. SiO2 can be advantageously at least 1.0 mol%, or at least 2.0 mol%, or at least 3.0 mol%, and / or advantageously up to 19.0 mol%, or up to 18.0 mol%, or up to 16.0 mol%, or up to 15.0 mol%.

[0028] Furthermore, the glass according to the present invention is suitable for temperature T max It has a temperature of ≤1330℃. maxThis is a composition-dependent variable of glass, describing the minimum temperature required in the melting process to produce a "complete" molten material from the starting material (e.g., raw material, fragments, etc.). A "complete" molten material exists when there are no molten residues, such as partially melted raw materials and crystals in the molten material. As explained at the beginning, the melting and clarification temperatures must be as low as possible to prevent heat-resistant materials from penetrating the glass and to avoid discoloration of the glass by multiple valence ions at lower oxidation states. This allows for high internal transmittance. Because the melting and clarification temperatures cannot be arbitrarily chosen to achieve the highest possible internal transmittance, there is an upper limit to the melting temperature, and therefore the temperature points described here are "T max It is also shown as "T max T is the lowest temperature at which a complete, crystal-free melt can still be produced. Based on this relationship, T max This is a good measure of the liquidus temperature of glass (see below).

[0029] Within the scope of the present invention, the T of the glass composition max The process was systematically identified in a series of laboratory-scale experiments, in which the same glass, each with a volume of 20 ml, was melted at different maximum temperatures starting from the initial components in small crucibles, with a temperature step of 10°C being selected. Subsequently, the melting results were visually evaluated from the lowest temperature to the highest temperature to determine whether a complete molten material had already formed or whether any residue and / or crystals were still present in the glass.

[0030] T was calculated for the composition in this way. max The values ​​could also be reproduced in larger volumes (e.g., 1 liter) of molten material in the laboratory. Furthermore, further experiments could be conducted on the temperature point T max It was shown that the temperature is only slightly higher than the liquidus temperature of the glass. The temperature point T was identified using an easy-to-handle laboratory method. max However, it was found to be a good measure of the liquidus temperature of glass, which is not precisely identified here.

[0031] In an advantageous further configuration of the present invention, T max The temperature is less than 1330°C, preferably up to 1320°C, preferably up to 1310°C, and more preferably up to 1300°C. Some advantageous variations are T with a maximum temperature of 1290°C or up to 1280°C. max It holds.

[0032] Furthermore, the glass according to the present invention has a refractive index n greater than 2.10. d This allows for the realization of a large FoV, which is advantageous for systems such as AR glasses.

[0033] In a favorable embodiment, refractive index n d n is greater than 2.100, favorably at least 2.110, favorably at least 2.115, favorably at least 2.120, favorably at least 2.125, or favorably at least 2.130, or at least 2.133. d The upper limit can be 2.20, 2.200, 2.195, 2.190, or 2.189. Therefore, the refractive index as a whole can favorably be in the range of 2.10 to 2.20. Refractive index n d This is known to those skilled in the art, and in particular, it exhibits a refractive index at a wavelength of approximately 587.6 nm (the wavelength of the helium d-line). How the refractive index n d Whether it can be identified is known to those skilled in the art.

[0034] Preferably, the refractive index is determined using a refractometer, particularly a V-block refractometer. In this case, a sample with a square or nearly square base (for example, having dimensions of approximately 20 mm × 20 mm × 5 mm) can be used. When measuring with a V-block refractometer, the sample is usually placed inside a V-shaped block prism with a known refractive index. The refractive index of the sample can be determined because the refraction of the incident light ray depends on the difference between the refractive index of the sample and the refractive index of the V-block prism. The measurement is preferably performed at a temperature of 22°C.

[0035] Within the scope of the present invention, a refractive index n greater than 2.10 d And, the low temperature point Tmax In other words, we have succeeded in providing optical glass having a low liquidus temperature, and thereby we can provide glass with high internal transmittance.

[0036] An advantageous embodiment of the glass has an internal transmittance of at least 75%, particularly at least 79%, particularly at least 82%, or at least 85%, or at least 87%, or at least 88%, or at least 90%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 97%, as measured at a wavelength of 460 nm and a sample thickness of 10 mm. In the function of the glass as a waveguide, for example, in the case of an image produced in AR glasses, the color perception is not distorted.

[0037] Internal transmittance or internal light transmission can be measured by methods well known to those skilled in the art, for example, in accordance with DIN 5036-1:1978. In this specification, the description of internal transmittance relates to a wavelength of 460 nm and a sample thickness of 10 mm. The description of "sample thickness" does not mean that the glass has this thickness, but merely describes the thickness to which the description of internal transmittance relates.

[0038] Unless otherwise specified or it is obvious to those skilled in the art, the measurements described herein are performed at 20°C and 101.3 kPa.

[0039] In an advantageous embodiment of the present invention, the density of the glass is advantageously <5.3 g / cm³. 3 , advantageously, <5.2 g / cm³ 3 , or <5.1 g / cm³ 3 , or <5.0 g / cm³ 3 That is the case.

[0040] In an advantageous embodiment of the present invention, the glass has a low density relative to its high refractive index, thereby reducing weight, for example, in the case of optical elements in AR glasses. d ) 2 / It may be advantageous if the numerical value of the density ratio is greater than 0.85, preferably greater than 0.87, more preferably greater than 0.89, more preferably greater than 0.90, and / or more preferably less than 0.99, more preferably less than 0.98, and more preferably less than 0.97.

[0041] In an advantageous embodiment of the present invention, the glass has an Abbe number greater than 18.5, i.e., dispersion (ν d ) has the following characteristics. Preferably, the variance is greater than 18.9, more preferably greater than 19.2, and / or even more preferably greater than 19.5, and / or favorably less than 30.0, or less than 25.0, or less than 24.0. d As is well known, the refractive index value n is obtained using a refractometer. d (At approximately 587.6 nm), n F (At approximately 486 nm), and n C (At approximately 656 nm) it was identified, ν d =(n d -1) / (n F -n C They are related to each other and calculated using ).

[0042] In a favorable embodiment, the glass has a glass transition temperature T of 600°C to 800°C. g This shows that, to be advantageous, T g The temperature can exceed 670°C, preferably exceed 700°C, and more preferably exceed 720°C. g This can be advantageous in terms of crystallization stability, because by doing so T max This is because the temperature difference becomes smaller, and the glass quickly reaches a stable glassy state. However, despite this, the glass can still be thermoformed and processed well.

[0043] The mean coefficient of thermal expansion (CTE) in the temperature range of 20 to 300°C should not be too high, and should be advantageously in the range of 8.0 to 12.0 ppm / K, particularly 8.3 to 11.5 ppm / K, and even more preferably 8.5 to 11.0 ppm / K. The CTE is specified in accordance with DIN ISO 7991:1987.

[0044] The glass of the present invention is advantageously titanium-containing, niobium-containing, and lanthanum-containing. Niobium-containing glass has a reputation for exhibiting poor internal transmittance in the visible spectral range close to UV, and for having a strong tendency towards interfacial crystallization due to its titanium content. This drawback does not occur in the glass described herein, or occurs only to a controllable degree.

[0045] Titanium equivalent (Ti 等価物 The glass components that make up the group are listed below: The titanium (TiO2) content in the glass can be at least 32.0 cation%, preferably at least 34.0 cation%, or at least 35.0 cation%. In some advantageous embodiments, the content is further at least 37.0 cation%, or at least 38.0 cation%. Some advantageous variants may also contain at least 39 cation% TiO2. The TiO2 content can be arbitrarily limited to a maximum of 52.0 cation%, 50.0 cation%, 49.0 cation%, 48.0 cation%, or 47.0 cation%. The TiO2 component plays a glass-forming role in the glass of the present invention and can therefore be shown as an incomplete glass-forming agent. If the TiO2 content is too high, the Abbe number decreases too much.

[0046] Niobium (NbO) in glass 2.5 The proportion of ) can be at least 3.0 cation%, preferably at least 4.0 cation%, preferably at least 4.5 cation%, preferably at least 5.0 cation%, or at least 6.0 cation%. NbO 2.5 The content can be arbitrarily limited to a maximum of 15.0 cation%, 13.0 cation%, 11.0 cation%, or 10.0 cation%. Some advantageous variants may also contain up to 9.0 cation%. TiO2 and LaO 1.5 In addition, NbO 2.5 This contributes to a high refractive index. However, too high NbO 2.5 The content is unfavorable in this glass system, leading to enhanced crystallization.

[0047] The proportion of zirconium (ZrO2) in the glass can be 0 to 11.0 cation %. Advantageously, at least 1.0 cation %, or at least 2.0 cation %, preferably at least 3.0 cation %, or at least 4.0 cation % of ZrO2 can be contained in the glass. ZrO2 contributes to achieving a glass range with a correspondingly low T max by adjusting the cation characteristic values so that a glass range with is achieved. The content of ZrO2 can optionally be limited to a maximum of 11.0 cation %, a maximum of 10.0 cation %, a maximum of 9.0 cation %, or a maximum of 8.0 cation %. Some advantageous variants can also contain a maximum of 7.0 cation %. ZrO2 contributes to achieving a high refractive index, but also increases the crystallization tendency of the glass in large amounts, so its content is optionally limited. Variants without ZrO2 are possible.

[0048] Tungsten (WO3) is an optional component of the glass. WO3 can be contained in the glass at a content rate of up to 5.0 cation %, advantageously up to 3.0 cation %, preferably up to 2 cation %, or up to 1.5 cation %, or up to 1 cation %, or up to 0.7 cation %. When this component is contained, the lower limit is advantageously 0.1 cation %, preferably 0.3 cation %. Variants without WO3 are possible and advantageous.

[0049] Tantalum (TaO 2.5 ) is an optional component of the glass. TaO 2.5 can be contained in the glass at a content rate of up to 5.0 cation %, advantageously up to 3.0 cation %, preferably up to 2.0 cation %, or up to 1.0 cation %, or up to 0.7 cation %. When this component is contained, the lower limit is advantageously 0.1 cation %, preferably 0.3 cation %. Variants without TaO 2.5 are possible and advantageous.

[0050] Aluminum (AlO 1.5) is an optional component of the glass and can contribute to chemical durability, but it also reduces the refractive index of the glass. Its content can be 0 to 5.0 cation %, or up to 3.0 cation %, or up to 2.0 cation %, or up to 1.0 cation %. AlO 1.5 When contained, it can be contained at a rate of at least 0.1 cation % or at least 0.5 cation %. Some embodiments are free of AlO 1.5 .

[0051] Antimony (SbO 2.5 ) and arsenic (AsO 2.5 ) are optional components, and each can be contained in the glass at a maximum content of 0.5 cation %, preferably at most 0.3 cation %, or at most 0.1 cation %, or at most 0.05 cation %, independently of each other. When at least one of these components is contained in the glass, 0.005 cation % can be the advantageous lower limit for each. Variants free of SbO 2.5 and / or AsO 2.5 are possible. Since the melt of the glass according to the invention has a low viscosity, the use of typical fining agents for reducing bubbles may not be necessary. Optionally, vacuum fining can be used. However, SbO 2.5 and / or AsO 2.5 can be added to the mixture to keep the glass melt in an oxidized state at high melting and fining temperatures, and thus ions of multiple valences, especially titanium and niobium ions, do not exist in their lower oxidation numbers, so the internal transmittance of the resulting glass is improved.

[0052] The total proportion of titanium equivalents (Ti 等価物 ) in the glass, that is, TiO2 + NbO 2.5 +ZrO2+WO3+AlO 1.5 +TaO 2.5 +AsO 2.5 +SbO 2.5It is advantageous if the total is at least 43.0 cation%, or at least 44.0 cation%. In a particularly advantageous embodiment, the total may be at least 45.0 cation%, or at least 46.0 cation%, advantageously at least 47.0 cation%, preferably at least 49.0 cation%, or at least 50.0 cation%, and / or advantageously up to 63.0 cation%, advantageously up to 61.0 cation%, preferably up to 59.0 cation%, or up to 58.0 cation%. Too much titanium equivalent leads to crystallization and high T max This could lead to that. The same applies to amounts that are too small.

[0053] In an advantageous embodiment of the present invention, the titanium equivalent is characterized by titanium (TiO2), niobium (NbO2), and 2.5 ), zirconium (ZrO2), antimony (SbO2) 2.5 ) and arsenic (AsO 2.5 It is composed of the total molar proportion of cations of ) and here, advantageously, titanium equivalent (Ti 等価物 The upper and / or lower limits mentioned above apply accordingly to the total proportion of ). The glass of this advantageous embodiment is essentially WO3, AlO 1.5 and TaO 2.5 It is self-evident that it is not included.

[0054] In a more advantageous embodiment, the titanium equivalent is characterized by titanium (TiO2) and niobium (NbO2). 2.5 It consists of the total molar proportion of cations of ) and zirconium (ZrO2), where titanium equivalent (Ti 等価物 The upper and / or lower limits mentioned above apply accordingly to the total proportion of ). The glass of this advantageous embodiment is essentially WO3, AlO 1.5 TaO 2.5 AsO 2.5 and SbO 2.5 It is self-evident that it is not included.

[0055] An advantageous embodiment of the present invention satisfies the following conditions: TiO2 content (in cation percentage) > NbO 2.5 The content of (cation percentage) of is greater than the content of (cation percentage) of ZrO2.

[0056] Lanthanum equivalent (La 等価物 The glass components that make up the group are listed below: Lantern in glass (LaO 1.5 The content can be at least 13.0 cation%, preferably at least 15.0 cation%, or at least 16.0 cation%. In some advantageous embodiments, the content is further at least 17.0 cation%, or at least 18.0 cation%. In some variants, the content is at least 19.0 cation%, or at least 20 cation%. LaO 1.5 The content can be arbitrarily limited to a maximum of 30.0 cation%, or a maximum of 29.0 cation%. Particularly advantageous embodiments include LaO with a maximum of 28.0 cation%, a maximum of 26.0 cation%, a maximum of 25.0 cation%, or a maximum of 24.0 cation%, or a maximum of 23.0 cation%. 1.5 It may have a content of TiO2 and NiO 2.5 In addition, LaO 1.5 This contributes to the high refractive index. LaO 1.5 An excessively high concentration of this substance leads to increased devitrification, and consequently, T max This will lead to an increase in [something].

[0057] Gadolinium (GdO) in glass 1.5 The proportion of ) can be 0 to 10.0 cation%. If it is present, its proportion can be favorably at least 1.0 cation%, favorably at least 2.0 cation%, or at least 3.0 cation%. GdO 1.5 The content can be arbitrarily limited to a maximum of 10.0 cation%, 9.0 cation%, 8.0 cation%, or 7.0 cation%. Several advantageous variants include GdO with a maximum of 6.0 cation% or 5.0 cation%. 1.5 It may also contain.

[0058] Yttrium (YO 1.5 ) is an optional component of the glass and may be present in the glass at a maximum content of 5.0 cation%, preferably 3.0 cation%, more preferably 2.0 cation%, or 1.5 cation%, or more preferably 1.0 cation%. If this component is present, the lower limit is preferably 0.1 cation%, more preferably 0.3 cation%. YO 1.5 Unincorporated variants are possible.

[0059] Ytterbium (YbO) 1.5 YbO is an optional component of the glass and may be present in the glass at a maximum content of 5.0 cation%, preferably 3.0 cation%, preferably 2 cation%, or 1.5 cation%, or 1.0 cation%. If this component is present, the lower limit is preferably 0.1 cation%, preferably 0.3 cation%. 1.5 Unincorporated variants are possible and advantageous.

[0060] Lanthanum equivalent in glass (La 等価物 The proportion of the total of ) that is, LaO 1.5 +GdO 1.5 +YO 1.5 +YbO 1.5 It is advantageous if the total amount in the glass is at least 21.0 cation%, preferably at least 22.0 cation%, preferably at least 23.0 cation%, or at least 24.0 cation%, and / or preferably up to 35.0 cation%, preferably up to 33.0 cation%, or preferably up to 31.0 cation%. Particularly advantageous embodiments may also contain up to 30.0 cation%, preferably up to 29.0 cation%, preferably up to 28.0 cation%, or according to some variants, up to 27.0 cation% of lanthanum equivalent. Too much lanthanum equivalent can lead to crystallization and high T max This could lead to that. The same applies to amounts that are too small.

[0061] In a more advantageous embodiment, the lanthanum equivalent is characterized by lanthanum (LaO 1.5), gadolinium (GdO 1.5 ) and yttrium (YO 1.5 ) is composed of the total molar proportions of cations, where favorably the upper and / or lower limits mentioned above apply to the total proportion of lanthanum equivalents (La equivalents). The glass of this favorable embodiment is essentially YbO 1.5 It is self-evident that it is not included.

[0062] An advantageous embodiment of the present invention satisfies the following conditions: LaO 1.5 Content (in cation percentage) > GdO 1.5 (Cation %) content > YO 1.5 The content (in cation percent).

[0063] In an advantageous embodiment of the present invention, TiO2 and LaO in glass 1.5 The proportion of the components is at least 53.0 cation%, preferably at least 55.0 cation%, preferably at least 57.0 cation%, preferably at least 59.0 cation%, and / or preferably up to 70.0 cation%, preferably up to 69 cation%, or up to 68 cation%.

[0064] According to a more favorable configuration, TiO2, LaO 1.5 and NbO 2.5 The proportion of the components is at least 60.0 cation%, preferably at least 63.0 cation%, preferably at least 65.0 cation%, preferably at least 67.0 cation%, and / or preferably up to 80.0 cation%, preferably up to 77 cation%, or preferably up to 75 cation%, preferably up to 73.0 cation%.

[0065] Regarding optical glass, (Ti in glass) 等価物 +La 等価物It may be advantageous if the total of (Ti) is at least 72.0 cation%, preferably at least 73.0 cation%, preferably at least 74.0 cation%, and / or preferably up to 85.0 cation%, preferably up to 84.0 cation%, preferably up to 83.0 cation%. Some advantageous variants are (Ti 等価物 +La 等価物 The total of ) may also have a lower limit of at least 75.0 cation%, or at least 76.0 cation%. The higher the above total, the higher the refractive index of the glass. However, with increasing total, the lower T max Consequently, it becomes difficult to provide glass with high internal transmittance and crystallization stability.

[0066] Silicon (SiO2) is a glass-forming agent. This component contributes to chemical durability. If it is used in very large quantities, the refractive index according to the present invention cannot be achieved. According to the present invention, the glass contains SiO2 in a proportion of >0 cation%. Optionally, the glass contains at least 1.0 cation%, at least 2.0 cation%, or at least 3.0 cation%. Some advantageous variants may contain at least 4.0 cation%, or at least 5.0 cation% of SiO2. The SiO2 content may be limited to less than 20.0 cation%, advantageously up to 18.0 cation%, or up to 16.0 cation%, or up to 14.0 cation%, or up to 13.0 cation%, or up to 12.0 cation%.

[0067] Boron (BO 1.5 ) also functions as a glass-forming agent. In the glass system according to the present invention, it has a temperature point T max This contributes to reducing . According to the present invention, the glass is BO 1.5 It contains in a proportion of >0 cation%. Optionally, the glass contains at least 1.0 cation%, at least 2.0 cation%, or at least 3.0 cation%. Some advantageous variants include BO containing at least 4.0 cation%, at least 5.0 cation%, or at least 6.0 cation%. 1.5It may contain BO. 1.5 The content can be limited to less than 20.0 cation%, preferably to a maximum of 19.0 cation%, or to a maximum of 18.0 cation%. Several advantageous variants are BO 1.5 It contains in a proportion of up to 17.0 cation%, or up to 16.0 cation%, or up to 14.0 cation%, or up to 12.0 cation%, or up to 11.0 cation%.

[0068] SiO2 and BO 1.5 It should be noted that, regarding the proportion of components, the proportion should be selected such that the condition 8.0 mol% ≤ (SiO2 + B2O3) ≤ 20.0 mol% according to the present invention is satisfied. Further advantageous upper and lower limits for this feature have already been shown above.

[0069] The glass may contain barium (BaO). In an advantageous embodiment, the BaO content is limited to a maximum of 6.5 cation%, preferably a maximum of 6.0 cation%, and in some advantageous variants, to a maximum of 5.5 cation%, because excessively high percentages lead to undesirable crystallization. When BaO is contained in the glass, this component can be at least 0.1 cation%, at least 0.2 cation%, at least 0.5 cation%, or at least 1.0 cation%, and in particular at least 2.0 cation%, or at least 3.0 cation%. The presence of BaO in the glass is approximately 10 6 dPas to 10 14 It can be beneficial for increasing viscosity and steepness in the high viscosity range up to dPas. A variant without BaO is also possible.

[0070] Zinc (ZnO), magnesium (MgO), calcium (CaO), and / or strontium (SrO) can optionally be used in the glass. They lower the melting temperature and stabilize the glass against crystallization without reducing its chemical durability to the same extent as alkali metal oxides. In this case, the ZnO content can range from 0 cation% to 5.0 cation%, preferably up to 4.0 cation%, or up to 3.0 cation%, or up to 2.0 cation%, or up to 1.0 cation%. Some advantageous embodiments are ZnO-free. The MgO content can range from 0 cation% to 2.0 cation%, or preferably up to 1.0 cation%. Advantageous embodiments are MgO-free. The CaO content can range from 0 cation% to 2.0 cation%, or preferably up to 1.0 cation%. Some advantageous embodiments are CaO-free. The SrO content can range from 0 cation% to 2.0 cation%, or preferably up to 1.0 cation%. Some advantageous embodiments are SrO-free. For the above components, the advantageous lower limits can be at least 0.1 cation%, or at least 0.3 cation%, or at least 0.5 cation%, respectively.

[0071] Alkali metal oxides, for example, LiO 0.5 NaO 0.5 , KO 0.5 , RbO 0.5 , CsO 0.5 These can be contained in the glass in proportions of up to 2 cations, preferably up to 1 cation, preferably up to 0.5 cations, for each individual component, or preferably for their total proportions. Smaller amounts of at least 0.1 cations, or at least 0.2 cations (for each individual component, or preferably for their total proportions), may be advantageous for the meltability of the glass. However, since these components reduce the refractive index, there is an upper limit to their content. An advantageous variant of the present invention is LiO 0.5 and / or NaO 0.5 and / or KO 0.5 and / or RbO0.5 and / or CsO 0.5 It is free of alkali metal oxides, and more importantly, it is free of alkali metal oxides.

[0072] Tin oxide (SnO2) does not act as a clarifying agent in the glass system according to the present invention, or only in very small amounts. However, it may be included as a glass component in amounts of up to 2 cations, up to 1 cation, or up to 0.5 cations. Preferably, the glass is SnO2-free.

[0073] In the case of ions with multiple valencies, a small amount of sulfate (SO3) may be included in the glass to contribute to the stabilization of higher oxidation states. If included, the proportion is at least 0.01 cation%. A higher proportion of sulfate increases the risk of enhanced bubble formation in the glass and the risk of platinum inclusion in the glass. Therefore, the proportion of sulfate can be advantageously up to 0.5 cation%, advantageously up to 0.1 cation%, and preferably up to 0.05 cation%. Preferably, the glass is SO3-free.

[0074] The glass may contain small amounts of hafnium (HfO2), preferably up to 0.1% cations or up to 0.05% cations. Typically, it is not actively added but enters the glass along with the ZrO2 component via the raw materials. When very pure ZrO2 raw materials are used, the glass is advantageously HfO2-free.

[0075] The optical glass may contain fluorine (F). An advantageous variant may contain up to 1 cation%, preferably up to 0.5 cation%, and more preferably up to 0.1 cation% of this component. An advantageous variant is F-free.

[0076] In a favorable embodiment, the glass has the following components in cation percent: [Table 1]

[0077] In a favorable embodiment, the glass has the following components in cation percent: [Table 2]

[0078] In a favorable embodiment, the glass has the following components in cation percent: [Table 3]

[0079] In a favorable embodiment, the glass comprises at least 95.0% cations, particularly at least 98.0% cations, or at least 99.0% cations, from the components described herein, particularly those listed in the table above. In one embodiment, the glass comprises essentially all of these components.

[0080] As already explained above, the addition of typical clarifying agents is not necessary because the molten material has low viscosity at the temperature required for melting. However, clarifying agents, such as AsO2, are not required. 2.5 SbO 2.5 If SO3 and / or Cl are added, their content can be clearly reduced, for example, to <0.1 cation%. Pure physical clarification is also possible and advantageous. Optionally, the glass may contain one or more of the following clarifying components in the proportions indicated in cation%: [Table 4]

[0081] In a favorable embodiment, the glass is essentially bismuth (BiO 1.5It is free of bismuth and / or lead (PbO) cations. The addition of bismuth disproportionately increases the density of the glass. Furthermore, bismuth ions are reduced to elemental bismuth at relatively low temperatures in the range of 1000°C, which leads to a strong gray coloration of the glass. PbO is also abandoned because it negatively affects the low density. Moreover, it is considered a toxic component.

[0082] Due to the high content of niobium, titanium, and lanthanum, expensive components such as tantalum and / or tungsten and / or ytterbium and / or germanium (GeO2) are not required, or are required only in small amounts, in order to obtain glass with the desired high refractive index. Lithium is known to be corrosive to ceramic bath and crucible materials, so it is used as little as possible or only in small amounts.

[0083] Optionally, the glass may contain phosphate (PO 2.5 It is not included because it significantly reduces the molten material, thus greatly increasing the oxygen demand of the molten material, which in turn increases the consumption of platinum and leads to discoloration of the glass.

[0084] The glass may optionally contain, with respect to each cation, one or more components selected from magnesium, cadmium, gallium, germanium, coloring components (e.g., cobalt, vanadium, chromium, molybdenum, copper, nickel), and combinations thereof. Components such as iron, manganese, selenium, tellurium, and / or thallium may be present in the glass in smaller proportions, for example, as impurities. Iron, selenium, and tellurium, as well as manganese, can function as redox partners. However, advantageously, these components, either individually or in combination, are not intentionally added to the glass.

[0085] In this specification, when it is stated that a glass is free of a certain component or does not contain a particular component, it means that this component may be present in the glass at most as an impurity. This means that they are not added in essential amounts. According to the present invention, an essential amount is less than 100 ppm, preferably less than 50 ppm, and most preferably less than 10 ppm (m / m).

[0086] In one embodiment, the present invention relates to a glass article having or made of the above-described glass. The glass article may take various forms. Optionally, the article may be • Glass substrates for structural members of optical components, particularly in AR glasses, especially glass substrates as components of laminated substrates. • Wafers, particularly those having a maximum diameter of 5.0 cm to 50.0 cm, or a diameter of 0.7 cm to 50 cm, preferably 3 cm to 45 cm, or 5 cm to 40 cm. Lenses, especially spherical lenses, prisms or aspherical bodies, and / or • Optical waveguides, especially fiber or plate It has the form of.

[0087] In a further embodiment, the present invention relates to the use of the glass or glass articles described herein in AR glasses, meta-optical components, wafer-level optical components, optical wafer applications, or typical optical components. Alternatively or additionally, the glass or glass articles described herein can be used as wafers, lenses, spherical lenses, or optical waveguides.

[0088] The glass according to the present invention can be melted from commercially available raw materials. For example, the glass can be melted using an apparatus such as that described in the unpublished German Patent Application No. 102020120168.0 (DE102020120168.0). [Brief explanation of the drawing]

[0089] [Figure 1]This figure shows the internal transmittance of glass example 31 in Table 1. [Figure 2] This figure shows the relationship between the cationic property value K and Tmax for the examples and comparative examples in Tables 1-9 and 14. [Figure 3] The table above shows the relationship between the cationic property value K and Tmax for the examples and comparative examples, and in addition to the examples shown in Figure 2, the examples in Tables 10 to 12 are shown. [Examples]

[0090] The compositions shown in Tables 1 to 14 below were melted and their properties investigated. Tables 1 to 13 show examples (Examples 1 to 99) according to the present invention, and Table 14 shows comparative examples (Comparative Examples A to G). The internal transmittance was determined for several glasses. The internal transmittance of a favorable example (Example 31) is shown in Figure 1.

[0091] Composition and properties [Table 5]

[0092] [Table 6]

[0093] [Table 7]

[0094] [Table 8]

[0095] [Table 9]

[0096] [Table 10]

[0097] [Table 11]

[0098] [Table 12]

[0099] [Table 13]

[0100] [Table 14]

[0101] [Table 15]

[0102] [Table 16]

[0103] [Table 17]

[0104] [Table 18]

[0105] drawing Figure 1 shows the internal transmittance of glass example 31 from Table 1. This example shows an internal transmittance of over 88% at 460 nm with a sample thickness of 10 mm. Furthermore, the transmittance curve shows a favorable steep decrease from the visible region of the spectrum to the subsequent UV region.

[0106] Figure 2 shows the cationic properties K and T for the examples and comparative examples in Tables 1-9 and 14.max This shows the relationship. The glasses according to the present invention shown in Tables 1-9 have cationic property values ​​greater than 2.0 and in the range of up to 2.8, along with a T of less than 1330°C. max This indicates that they have a relatively low liquidus temperature. Furthermore, all examples have a refractive index n greater than 2.10. d It has the following characteristics. Therefore, within the scope of the present invention, a stable glass range at low liquidus temperatures has been found in high refractive index glass systems.

[0107] Figure 3 shows the cationic property values ​​K and T for the examples and comparative examples in the table above. max This shows the relationship. In addition to the examples shown in Figure 2, Tables 10 to 12 show the examples. Examples with a refractive index value above 2.10 and a cationic property value above 1.8 and in the range up to 2.0 are also shown here, but T below 1330°C max This means that they can both have relatively low liquidus temperatures.

[0108] Within the scope of the present invention, it has been found that glasses having a cationic property value greater than 2.0 exhibit a lower crystallinity tendency than glasses having a cationic property value of up to 2.0, which has a stronger crystallinity tendency. The enhanced crystallinity tendency reduces the process window during manufacturing, thus requiring more effort for such glasses. Within the process window, the melting temperature is T max It is superior. However, the temperature cannot be arbitrarily chosen to be high enough so that the viscosity is not too low and the glass can be handled, for example, in relation to hot forming. A further consequence of the enhanced crystallization tendency may be that, for example, only smaller glass sizes can be manufactured.

Claims

1. Refractive index n greater than 2.10 d and at least TiO 2 , NbO 2.5 and LaO 1.5 1. An optical glass comprising: Cationic characteristic value K 1.8<K≦28, where K=(Ti 等価物 +SiO 2 + (BO 1.5 ) / 2) / (La 等価物 ) and Ti 等価物 , SiO 2 , B.O. 1.5 and La 等価物 The molar proportion of is entered into the cationic characteristic value K in cationic %. Glass component SiO 2 and B 2 O 3 The total of 8.0 mol% or less (SiO 2 +B 2 O 3 )≦20.0 mol%, where B 2 O 3 is greater than 0 mol % and SiO 2 The proportion of is greater than 0 mol % • Temperature T max ≤1330℃ The optical glass having the above structure.

2. An internal transmittance τ of at least 75%, in particular at least 79%, or at least 82%, or at least 85%, or at least 87%, or at least 88%, or at least 90%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 97%, measured at a wavelength of 460 nm and a sample thickness of 10 mm. i The optical glass of claim 1 , wherein

3. 5.3 g / cm 3 and / or a density of greater than 0.85 (n d ) 2 2. The optical glass of claim 1, wherein the ratio of the refractive index to the density of the glass is:

4. TiO in glass 2 and LaO 1.5 the proportion of the component is at least 53.0 cation%, advantageously at least 55.0 cation%, advantageously at least 57.0 cation%, preferably at least 59.0 cation%, and / or TiO 2 , LaO 1.5 and NbO 2.5 2. The optical glass according to claim 1, wherein the proportion of the component is at least 60.0 cation %, preferably at least 63.0 cation %, preferably at least 65.0 cation %, preferably at least 67.0 cation %.

5. Features include: ・Ti 等価物 a proportion of at least 43.0 cation % and / or at most 63.0 cation %, ・La 等価物 a proportion of at least 21.0 cation % and / or at most 35.0 cation %, ・ (Ti 等価物 +La 等価物 ) sum of at least 72.0 cation % and / or at most 85.0 cation % The optical glass of claim 1 , wherein the optical glass has at least one of the following properties:

6. La 等価物 and / or Ti 等価物 6. The optical glass according to claim 5, wherein the proportion of is at least 45.0 cation %.

7. 2. The optical glass according to claim 1, wherein the cationic character value is at least 1.9, preferably at least 2.0, or above 2.0, preferably at least 2.1, preferably at least 2.2, or at least 2.

25.

8. 2. The optical glass of claim 1, comprising the following components in cationic percentages: Table 1

9. 2. The optical glass of claim 1, comprising the following components in cationic percentages: Table 2

10. 2. The optical glass of claim 1, comprising the following components in cationic percentages: Table 3

11. BaO content of up to 6.5 cation % and / or TiO of at least 39 cation % 2 The optical glass of claim 1 having a content of

12. An Abbe number (ν) greater than 18.5, or greater than 18.9, or greater than 19.2, or greater than 19.5, and / or less than 30.0, or less than 25.0, or less than 24.0 d 2. The optical glass of claim 1, wherein

13. 10. The optical glass of claim 1, wherein the glass is essentially free of one or more components selected from, for each cation, bismuth, lead, germanium, phosphate, lithium, magnesium, cadmium, gallium, coloring components (e.g., cobalt, vanadium, chromium, molybdenum, copper, nickel), and combinations thereof.

14. A glass article comprising the optical glass of claim 1, Glass substrates for the construction of optical components, in particular in AR glasses, in particular as constituents of substrate stacks; Wafers, in particular wafers having a maximum diameter of 5.0 cm to 50.0 cm, or a diameter of 0.7 cm to 50 cm, preferably 3 cm to 45 cm, or 5 cm to 40 cm; lenses, in particular spherical lenses, prisms or aspherical bodies, and / or Optical waveguides, especially fibers or plates The glass article in the form of

15. Use of the optical glass according to any one of claims 1 to 13 or the glass article according to claim 14 in AR glasses, wafer level optics, meta-optics, optical wafer applications or classical optics and / or as a wafer, lens, spherical lens or optical waveguide.

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