High refractive index glass for high-transmittance fiber-optic image-conversion elements and method for producing the same

Abstract

The application discloses high-refractive glass for high-transmittance optical fiber image transmission elements and a preparation method thereof. The glass is composed of the following components: SiO2 15.0-25.0%, Al2O3 0-0.5%, B2O3 20.0-30.0%, MgO 1.01-2.0%, SrO 1.0-5.0%, BaO 15.0-25.0%, ZnO 0.5-2.0%, SnO2 0.1-0.2%, TiO2 5.0-9.0%, WO3 1.0-5.0%, La2O3 5.0-10.0%, Nb2O5 1.0-5.0%, Y2O3 0.5-2.0%, Ta2O5 1.1-5.0%, Gd2O3 0-0.9%. The application has good transmittance, high refractive index and high strain point temperature, and is used for filling glass of optical fiber image transmission elements.

Description

Technical Field

[0001] This invention relates to the field of fiber optic imaging element manufacturing, and particularly to a high-refractive-index glass for high-transmittance fiber optic imaging elements and its preparation method. Background Technology

[0002] Fiber optic imaging elements, including optical fiber panels, fiber optic image inverters, fiber optic tapers, and fiber optic image bundles, are high-performance optoelectronic imaging devices. They employ unique formulations of sheath, core, and absorber materials, and are manufactured using vacuum control and a rod-tube combined drawing process. This results in products with excellent airtightness, low distortion, and few speckles. They feature simple structure, small size, light weight, large numerical aperture, high light transmission efficiency, low interstage coupling loss, high coupling efficiency, high resolution, and clear, realistic images. Optically, they possess zero thickness, improving edge image quality. Fiber optic imaging elements are high-resolution image transmission elements formed by the thermal fusion pressing of tens of millions of parallel optical fibers. They are key materials for image intensifiers and high-definition displays, widely used in various cathode ray tubes, camera tubes, charge-coupled devices, low-light night vision devices, medical device displays, high-definition television imaging, and other instruments and equipment requiring image transmission in military, criminal investigation, aerospace, and medical fields. They represent a cutting-edge high-tech product in the optoelectronic industry of this century.

[0003] The most typical application of fiber optic imaging elements is as the optical input and output windows of low-light image intensifiers, and their transmittance performance plays a crucial role in improving the quality of imaging devices. In China, fiber optic imaging elements are considered labor-intensive and capital-intensive products because most of their manufacturing processes rely on manual labor. In developed countries, higher labor costs and expensive raw material processing result in production costs several times higher than similar domestic products, leading to higher prices and lower profits. Furthermore, the fabrication of fiber optic imaging elements requires the use of glass materials with high refractive index and high transmittance. In recent years, with the increasing international emphasis on environmental protection, the use of oxides of some heavy metal elements that seriously harm the environment, such as As₂O₃, Sb₂O₃, PbO, and CdO, has been gradually banned. Therefore, how to improve the refractive index and transmittance of glass materials used in fiber optic imaging elements, thereby improving the effective numerical aperture, transmittance, and transmittance uniformity of the fiber optic imaging elements, and thus better enhancing the optical performance of fiber optic panels, fiber optic image converters, and fiber optic tapers, is a pressing problem that needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a glass with high refractive index and high strain point temperature for high-transmittance fiber optic imaging elements.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-refractive glass composition for high-transmittance optical fiber image transmission element is provided, which is composed of the following components in mole percentage:

[0007]

[0008] The application further provides a preferred technical scheme, a high-refractive glass composition for high-transmittance optical fiber image transmission element, which is composed of the following components in mole percentage:

[0009]

[0010]

[0011] The application further provides a method for preparing the high-refractive glass for high-transmittance optical fiber image transmission element using the composition, which comprises the following steps:

[0012] (1) uniformly mixing raw materials of quartz sand, aluminum oxide, boric acid or boric anhydride, basic magnesium carbonate, strontium carbonate, barium nitrate, zinc oxide, tin dioxide, titanium dioxide, tungsten trioxide, lanthanum oxide, niobium oxide, yttrium oxide, tantalum oxide and gadolinium oxide according to the requirements of batching, and then putting them into a platinum-gold crucible;

[0013] (2) melting at a first predetermined temperature, stirring 2-3 times during the glass melting process, and then cooling to a second predetermined temperature for clarification;

[0014] (3) casting the clarified molten glass into a predetermined glass product;

[0015] (4) then annealing the shaped glass product in an annealing furnace, and cooling to room temperature with the furnace.

[0016] The first predetermined temperature is 1450-1550℃; and the melting time is 5-10 hours.

[0017] The second predetermined temperature is 1380-1420℃; and the clarification time is 1.5-2.5 hours.

[0018] The annealing process is to keep the temperature at 600-615℃ for 1.5-2.5 hours, and then to cool to 100℃ with a cooling time of 20-24 hours.

[0019] The application further provides a high-refractive glass for high-transmittance optical fiber image transmission element, which is prepared according to the method.

[0020] The high-refractive glass has a refractive index of 1.80-1.82, and an average linear thermal expansion coefficient of (90±5)×10 -7The high-refractive glass has a strain point temperature of 620-640 DEG C, a transmittance of more than 95% in the spectrum of 400-700 nm, and a good anti-crystallization property.

[0021] The application further provides the high-refractive glass for the high-transmittance optical fiber image transmission element as a filling glass fiber on the optical fiber image transmission element.

[0022] The cross section of the filling glass fiber is triangular, which is used to be inserted into the triangular hole of the primary composite rod.

[0023] In the composition of the high-refractive glass for the high-transmittance optical fiber image transmission element, SiO2 is the main body of the glass forming skeleton and is the main component in the glass skeleton. The mole percentage (mol. %) of SiO2 is 15.0-25.0. When the content of SiO2 is less than 15.0 mol. %, it is difficult to obtain the glass with high refractive index, and the chemical stability of the glass is reduced; when the content of SiO2 is more than 25.0 mol. %, the high-temperature viscosity of the glass is increased, the melting temperature of the glass is too high, and the thermal expansion coefficient of the glass is reduced.

[0024] Al2O3 is the intermediate oxide of the glass, Al 3+ There are two coordination states in the glass, i.e. in the tetrahedron or octahedron, when there is enough oxygen in the glass, the aluminum-oxygen tetrahedron [AlO4] is formed to form a continuous network with the silicon-oxygen tetrahedron, when there is not enough oxygen in the glass, the aluminum-oxygen octahedron [AlO6] is formed to be in the hole of the silicon-oxygen structure network, so that in a certain content range, it can be the same as SiO2 to become the main body of the glass network. Al2O3 can significantly improve the strain point temperature of the glass material, and is the main component for solving the high transmittance of the optical fiber image transmission element. The mole percentage of Al2O3 is 0-0.5 mol. %, preferably 0.1-0.5 mol. %, when the content of Al2O3 is more than 0.5 mol. %, the melting temperature of the glass is significantly increased, and the high-temperature viscosity of the glass is significantly increased.

[0025] B2O3 is the glass forming oxide and the component of the glass skeleton, and is also a fluxing agent for reducing the melting viscosity of the glass. The boron-oxygen triangle [BO3] and the boron-oxygen tetrahedron [BO4] are the structural components, and boron can exist in the form of the triangle [BO3] or the boron-oxygen tetrahedron [BO4] under different conditions. Under the high-temperature melting condition, the boron-oxygen tetrahedron is generally difficult to form and can only exist in the form of the triangle, but under the low-temperature condition, B 3+It has the tendency to capture free oxygen to form tetrahedron, which makes the structure compact and increases the low temperature viscosity of the glass. However, it also has the characteristics of reducing the viscosity of the glass at high temperature and increasing the viscosity of the glass at low temperature, which is the main component for reducing the refractive index of the glass. The molar percentage (mol. %) of B2O3 is 20.0-30.0. If the content of B2O3 is less than 20.0 mol. %, it cannot play the role of fluxing, and at the same time, it will reduce the chemical stability of the glass. If the content of B2O3 is greater than 30.0 mol. %, it will reduce the refractive index of the glass, and at the same time, it will increase the phase separation tendency of the glass.

[0026] MgO is an oxide outside the glass structure network. The molar percentage (mol. %) of MgO is 1.01-2.0. If the content of MgO is greater than 2.0 mol. %, it will reduce the chemical stability of the glass and increase the thermal expansion coefficient of the glass.

[0027] SrO is an oxide outside the glass structure network. The molar percentage (mol. %) of SrO is 1.0-5.0. If the content of SrO is greater than 5.0 mol. %, it will reduce the chemical stability of the glass and increase the thermal expansion coefficient of the glass.

[0028] BaO is an oxide outside the glass structure network. It can effectively increase the refractive index of the glass. The molar percentage (mol. %) of BaO is 15.0-25.0. If the content of BaO is less than 15.0 mol. %, it will significantly reduce the refractive index of the glass. If the content of BaO is greater than 25.0 mol. %, it will increase the crystallization temperature of the glass, increase the crystallization tendency of the glass, and at the same time, significantly increase the density of the glass.

[0029] ZnO is an oxide that adjusts the melting temperature of the glass and the crystallization performance of the glass. The molar percentage (mol. %) of ZnO is 0.5-2.0. If the content of ZnO is greater than 2.0 mol. %, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0030] SnO2 is a glass clarifier. The molar percentage (mol. %) of SnO2 is 0.1-0.2. If the content of SnO2 is greater than 0.2 mol. %, it will increase the crystallization tendency of the glass.

[0031] TiO2 is used to increase the refractive index and transmittance of the glass. The molar percentage (mol. %) of TiO2 is 5.0-9.0. If the content of TiO2 is greater than 9.0 mol. %, it will reduce the transmittance of the glass.

[0032] WO3 is an oxide that adjusts the crystallization performance of the glass. The molar percentage (mol. %) of WO3 is 1.0-5.0. If the content of WO3 is greater than 5.0 mol. %, it will increase the crystallization tendency of the glass.

[0033] La2O3 is a lanthanide rare earth oxide that can increase the refractive index of glass. The molar percentage (mol.%) of La2O3 is 5.0-10.0. When the La2O3 content is greater than 10.0 mol.%, it will cause the coefficient of thermal expansion of the glass to increase.

[0034] Nb2O5 is also a rare earth oxide that can increase the refractive index of glass. The molar percentage (mol.%) of Nb2O5 is 1.0-5.0, but when the Nb2O5 content is greater than 5.0 mol.%, it will cause the density and thermal expansion coefficient of the glass to increase.

[0035] Y2O3 is a lanthanide rare earth oxide that can improve the refractive index of glass and is also used to adjust the crystallization properties of glass. The molar percentage (mol.%) of Y2O3 is 0.5-2.0, but when the Y2O3 content is greater than 2.0 mol.%, it will cause the coefficient of thermal expansion of glass to increase.

[0036] Ta2O5 is also a rare earth oxide that can increase the refractive index of glass. The molar percentage (mol.%) of Ta2O5 is 1.1-5.0, but when the Ta2O5 content is greater than 5.0 mol.%, it will cause the density and thermal expansion coefficient of the glass to increase.

[0037] Gd2O3 is also a rare earth oxide that can increase the refractive index of glass. It is also an oxide used to adjust the crystallization properties of glass. The molar percentage (mol.%) of Gd2O3 is 0-0.9. When the Gd2O3 content is greater than 0.9 mol.%, it will cause the density and thermal expansion coefficient of the glass to increase.

[0038] The present invention preferably uses a triangular cross-section for the filler glass filament inserted into the triangular aperture. This triangular structure is used as the filler glass filament in fiber optic imaging elements. For apertures of the same area, the triangular structure has a higher filling coefficient than the circular structure, and the triangular structure is also more stable. The triangular filler glass filament prevents slippage and displacement of the internal fiber structure of the fiber optic imaging element, maintaining a stable total internal reflection structure. Simultaneously, it significantly increases the useful light flux incident on the optical fiber, thereby improving the transmittance and transmittance uniformity of the fiber optic imaging element.

[0039] Compared with the prior art, the technical solution of using high-refractive-index filled glass for high-transmittance optical fiber imaging elements provided by the present invention has the following advantages:

[0040] (1) It has a high refractive index, with a refractive index n D It can reach 1.80-1.82;

[0041] (2) The average linear thermal expansion coefficient in the range of 30–300℃ is (90±5)×10 -7 / ℃;

[0042] (3) The strain point temperature of the glass is 620-640℃;

[0043] (4) The glass has a transmittance of more than 95% in the 400-700nm spectrum and has good transparency and transmittance to visible light radiation.

[0044] (5) It has good chemical stability;

[0045] (6) The glass does not crystallize or separate phase when kept at 850-900℃ for 6 hours, and has good anti-crystallization properties;

[0046] (7) It has high-temperature viscosity characteristics that match those of leather glass.

[0047] The high-refractive-index glass of the present invention has good transmittance, high refractive index and high strain point temperature; it can be used to prepare filling glass for filling the triangular gap of primary composite rods in fiber optic imaging elements, which can not only improve the effective numerical aperture of the glass, but also greatly improve the optical performance of fiber optic imaging elements, especially transmittance performance. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the internal structure of the optical fiber that makes up the optical fiber imaging element, as provided in an embodiment of the present invention.

[0049] Among them, 1 is the filling glass fiber, 2 is the core glass, and 3 is the skin glass. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and specific examples, but this is not intended to limit the present invention.

[0051] See Figure 1 After the cladding glass tube and the core glass rod are matched, they are drawn into monofilaments. The monofilaments include an outer cladding glass 3 and an inner core glass 2. Multiple monofilaments are closely arranged into a hexagon with a regular hexagonal cross-section, and a filling glass filament 1 is provided between adjacent monofilaments.

[0052] In this document, all "molar percentage (mol.%)" are based on the total molar amount of the final glass composition. The parameters, measurement methods, and instruments used for the high-refractive-index filled glass used in the optical fiber imaging element of this invention are as follows:

[0053] (1) Refractive index n D The refractive index of the glass at λ = 589.3 nm was determined using a refractive index meter.

[0054] (2) Average linear thermal expansion coefficient α at 30-300℃ 30 / 300 [×10-7 The thermal expansion coefficient is measured by a horizontal dilatometer, and the method specified in GB / T 16920-2015 is used.

[0055] (3) The glass strain point temperature is measured by the method specified in GB / T 28196-2011.

[0056] The glass chemical compositions (mol.%) and properties of the examples are listed in detail in Table 1.

[0057] Table 1 Glass chemical compositions (mol.%) and properties of the examples

[0058] Composition (mol. %) Example 1 Example 2 Example 3 Example 4 Example 5 SiO2 22.7 20.31 25.00 15.00 17.00 Al2O3 0.1 0.15 0.25 0.50 0.30 B2O3 26.8 24.33 20.00 28.60 30.00 MgO 1.01 1.16 1.65 2.00 1.85 SrO 3.4 3.7 1.00 4.20 5.00 BaO 16.2 21.85 25.00 15.00 24.10 ZnO 0.5 2.0 1.70 1.60 1.50 SnO2 0.1 0.16 0.20 0.14 0.18 TiO2 8.07 8.61 5.00 9.00 5.37 [WO3] 4.0 1.0 3.00 5.00 2.00 La2O3 7.67 7.55 9.00 10.00 5.00 [Nb2O5] 3.22 3.53 5.00 3.10 1.00 [Y2O3] 0.5 1.42 1.20 1.80 2.00 [Ta2O5] 5.0 4.13 1.10 3.26 4.00 Gd2O3 0.73 0.1 0.90 0.80 0.70 Expansion coefficient 85 90 89 91 87 Strain point temperature 624 628 630 635 633 Refractive index 1.81 1.82 1.82 1.80 1.81

[0059] The raw materials and requirements of the raw materials used in the following examples are as follows:

[0060] Quartz sand (high purity, 1% or less of 150 μm sieve oversize, 30% or less of 45 μm sieve undersize, Fe2O3 content less than 0.01 wt.%), alumina (analytical pure, average particle size 50 μm), boric acid or boric anhydride (10% or less of 400 μm sieve oversize, 10% or less of 63 μm sieve undersize), basic magnesium carbonate (analytical pure, average particle size 50 μm), strontium carbonate (analytical pure, purity ≥ 99.0%), barium nitrate (analytical pure, purity ≥ 99.0%), zinc oxide (analytical pure), tin dioxide (analytical pure), titanium dioxide (analytical pure), tungsten trioxide (analytical pure), lanthanum sesquioxide (5N), niobium pentoxide (5N), yttrium oxide (5N), tantalum oxide (5N), gadolinium sesquioxide (5N).

[0061] Example 1

[0062] The raw materials are selected according to the glass composition of Example 1 in Table 1, and the oxides of the variable valence elements such as Fe2O3 in the glass raw materials are strictly controlled. The Fe2O3 content of the finished glass is less than 150 PPM, and the batch is made to meet the glass chemical composition in Table 1. Then, the high refractive index glass is prepared according to the following steps:

[0063] (1) The raw materials quartz sand, alumina, boric acid or boric anhydride, basic magnesium carbonate, strontium carbonate, barium nitrate, zinc oxide, tin dioxide, titanium dioxide, tungsten trioxide, lanthanum oxide, niobium oxide, yttrium oxide, tantalum oxide and gadolinium oxide are mixed uniformly according to the batch requirements and then put into a platinum crucible;

[0064] (2) Melt at a temperature of 1500°C for 8 hours, and stir 3 times during the glass melting process, and then cool to 1410°C and clarify for 2 hours;

[0065] (3) Pour the clarified molten glass liquid into a specified glass product;

[0066] (4) Then the shaped glass product is annealed in an annealing furnace, the annealing process is 605 °C for 2 hours, then cooled to 100 °C in 24 hours, and then cooled to room temperature in the furnace. The test performance is shown in Table 1.

[0067] Example 2

[0068] The actual composition of the glass refers to Table 1 Example 2, and the high refractive index glass is prepared according to the following steps:

[0069] (1) The raw materials quartz sand, alumina, boric acid or boric anhydride, basic magnesium carbonate, strontium carbonate, barium nitrate, zinc oxide, tin dioxide, titanium dioxide, tungsten trioxide, lanthanum oxide, niobium oxide, yttrium oxide, tantalum oxide and gadolinium oxide are mixed uniformly according to the batching requirements and then put into a platinum gold crucible;

[0070] (2) Melt at 1450 °C for 10 hours, and stir 3 times during the glass melting process, and then cool to 1380 °C for 2.5 hours for fining;

[0071] (3) The molten glass liquid after fining is cast into a specified glass product;

[0072] (4) Then the shaped glass product is annealed in an annealing furnace, the annealing process is 600 °C for 2.5 hours, then cooled to 100 °C in 20 hours, and then cooled to room temperature in the furnace. The test performance is shown in Table 1.

[0073] Example 3

[0074] The actual composition of the glass refers to Table 1 Example 3, and the high refractive index glass is prepared according to the following steps:

[0075] (1) The raw materials quartz sand, alumina, boric acid or boric anhydride, basic magnesium carbonate, strontium carbonate, barium nitrate, zinc oxide, tin dioxide, titanium dioxide, tungsten trioxide, lanthanum oxide, niobium oxide, yttrium oxide, tantalum oxide and gadolinium oxide are mixed uniformly according to the batching requirements and then put into a platinum gold crucible;

[0076] (2) Melt at 1550 °C for 5 hours, and stir 2 times during the glass melting process, and then cool to 1420 °C for 1.5 hours for fining;

[0077] (3) The molten glass liquid after fining is cast into a specified glass product;

[0078] (4) Then the shaped glass product is annealed in an annealing furnace, the annealing process is 615 °C for 1.5 hours, then cooled to 100 °C in 20 hours, and then cooled to room temperature in the furnace. The test performance is shown in Table 1.

[0079] Example 4

[0080] The high refractive index glass was prepared according to the same procedure and process conditions as in Example 1, with the actual glass composition referring to Table 1, Example 4.

[0081] Example 5

[0082] The high refractive index glass was prepared according to the same procedure and process conditions as in Example 1, with the actual glass composition referring to Table 1, Example 5.

[0083] The high refractive index, high strain point glass of the present application can be used as a filler glass for making high transmission optical fiber image elements.

[0084] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A composition of high-refractive-index glass for high-transmittance fiber optic imaging elements, characterized in that, It consists of the following components in molar percentage: The strain point temperature of the high refractive index glass is 620-640℃.

2. The composition according to claim 1, characterized in that, It consists of the following components in molar percentage: TiO2 5.0-9.0% WO3 1.0-5.0% La2O3 5.0-9.0% Nb2O5 1.0-5.0% Y2O3 0.5-2.0% Ta2O5 1.1-5.0% Gd2O3 0.1-0.9%.

3. A method for preparing high-transmittance fiber optic imaging element high-refractive-index glass using the composition of claim 1 or 2, characterized in that, Includes the following steps: (1) Mix the raw materials quartz sand, alumina, boric acid or boric anhydride, basic magnesium carbonate, strontium carbonate, barium nitrate, zinc oxide, tin dioxide, titanium dioxide, tungsten trioxide, lanthanum oxide, niobium oxide, yttrium oxide, tantalum oxide and gadolinium oxide evenly according to the ingredient requirements and then put them into a platinum crucible. (2) Melt at the first predetermined temperature, stir 2-3 times during the glass melting process, and then cool down to the second predetermined temperature for clarification; (3) Cast the clarified molten glass into specified glass products; (4) Then the formed glass product is annealed in an annealing furnace and then cooled to room temperature in the furnace.

4. The method according to claim 3, characterized in that, The first predetermined temperature is 1450-1550℃; the melting time is 5-10 hours.

5. The method according to claim 3, characterized in that, The second predetermined temperature is 1380-1420℃; the clarification time is 1.5-2.5 hours.

6. The method according to claim 3, characterized in that, The annealing process involves holding the temperature at 600-615℃ for 1.5-2.5 hours, then cooling it down to 100℃ over 20-24 hours.

7. A high-refractive-index glass for a high-transmittance fiber optic imaging element, characterized in that, Prepared according to the method described in any one of claims 3-6.

8. The high-refractive-index glass for high-transmittance fiber optic imaging elements according to claim 7, characterized in that, The high-refractive-index glass has a refractive index of 1.80–1.82; and an average linear thermal expansion coefficient of (90±5)×10⁻⁶ in the temperature range of 30–300℃. -7 The high-refractive-index glass has a transmittance greater than 95% in the 400-700nm spectrum and does not crystallize or separate into phases when kept at 850-900℃ for 6 hours.

9. The application of high-refractive-index glass as filler glass filament in a high-transmittance optical fiber imaging element as described in claim 7 or 8.

10. The application according to claim 9, characterized in that, The cross-section of the filling glass wire is triangular, and it is used to insert into the triangular hole of the primary composite rod.

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