Glass for high-resolution super-narrow twisted fiber area optical fiber inverter and method of making same

Abstract

The application discloses a kind of high-resolution super-narrow torsion wire area optical fiber inverter glass and preparation method thereof, the glass is composed of the following molar percentage components: SiO2 78.1-80.0%, Al2O3 3.1-7.0%, B2O32.0-8.0%, Li2O 0-1.0%, Na2O 0-2.9%, K2O 5.1-10.0%, CaO 1.1-3.0%, SrO 0-1.0%, ZnO 1.1-2.0%, TiO2 0-1.0%, CeO2 0.05-0.2%, MgF2 0-2.0%, CaF2 0.05-2.0%.The application has the characteristics of excellent chemical performance, glass composition is stable, low refractive index, excellent anti-crystallization performance.Suitable for preparing the skin layer glass of high-resolution super-narrow torsion wire area optical fiber inverter.

Description

Technical Field

[0001] This invention relates to the field of fiber optic image transmission element manufacturing, and in particular to a high-resolution ultra-narrow twisted fiber optic image inverter and its preparation method. Background Technology

[0002] Helmet-mounted night vision devices (HMDs) were developed to help soldiers adapt to more complex nighttime combat environments, enabling them to detect and see targets earlier and more clearly in all weather conditions. HMDs are essentially low-light night vision devices mounted on a helmet, primarily used by pilots, night-flying pilots, and special forces in operations, and have become an essential piece of equipment for soldiers. However, mounting the night vision device in front of a standard flight helmet shifts the combined center of gravity of the device, helmet, and head forward and upward from the normal head center of gravity. Some systems use counterweights or batteries for the night vision device at the rear of the helmet to correct some of this shift, but this increases the overall weight on the head and restricts head movement within the helmet, significantly reducing the pilot's potential field of vision. Furthermore, due to their excessive weight, unstable center of gravity, enlarged profile, limited noise reduction, and poor comfort, helmet-mounted night vision devices have become a significant factor affecting pilot health and flight safety. To maintain the advantages of night vision technology and meet the overall requirements of high-mobility combat operations for soldiers, helmet-mounted night vision devices are constantly evolving towards miniaturization, lightweighting, and integration. The goal is to reduce size and weight, minimize the protrusion of the objective and eyepiece lenses, bring the center of gravity closer to the face, increase the field of view, and enhance visibility, making them more suitable for prolonged head-mounted use. The fiber optic image inverter is the core optical component of a helmet-mounted night vision device. It is a high-performance optoelectronic imaging device with a large numerical aperture, high light transmission efficiency, high resolution, and clear, realistic image transmission. Optically, it features zero thickness, simple structure, small size, light weight, good airtightness, low distortion, few speckles, low interstage coupling loss, and high coupling efficiency, which improves edge image quality. As the optical output window of a low-light image intensifier, it plays a crucial role in improving the quality of the imaging device and is a cutting-edge high-tech product in the global optoelectronic industry.

[0003] To meet the demands for miniaturization, weight reduction, and improved resolution and image clarity in helmet-mounted night vision devices, there has been a persistent goal of reducing the overall weight and size of these devices by miniaturizing the height, volume, and weight of the fiber optic image reverser. If the weight of the fiber optic image reverser can be reduced by 30%, the overall weight of related structures, components, and battery structures associated with the helmet-mounted night vision device can be reduced by more than 50%. This would significantly enhance the flexibility and mobility required for soldiers during combat, playing a crucial role in improving the night combat capabilities of the armed forces. Therefore, developing an ultra-narrow twisted fiber optic image reverser has become an urgent need to meet the miniaturization and weight reduction requirements of helmet-mounted night vision devices.

[0004] Ultra-narrow twisted-zone fiber optic image reversers are made by compressing the twisted zone of a fiber optic image reverser. However, the compression of the twisted zone in a normal fiber optic image reverser causes more severe stretching and deformation of the edge fibers, and slippage between optical fibers. In particular, the sheath thickness of the edge optical fibers will be stretched and thinned. Since the optical fibers are completely fused together by the sheath glass, the adjacent optical fibers are very close. Due to the compression of the twisted zone, the sheath glass will have uneven stretching and deformation of the fibers. This causes the incident light entering the core glass of the optical fiber to cross-beam between the sheaths of adjacent fibers. As a result, the input light will penetrate the sheath during total internal reflection, causing the total internal reflection mechanism of the edge optical fibers to disappear, directly affecting the light transmission and image transmission performance of the optical fibers. In particular, the narrower the twisted region of the fiber optic image reverser, the greater the difficulty in fabricating the ultra-narrow twisted region image reverser. During the fabrication process, not only edge resolution must be considered, but also the effects of material compatibility and component interdiffusion during the fabrication process. Therefore, the fabrication of ultra-narrow twisted region fiber optic image reversers is extremely difficult.

[0005] The ultra-narrow twisted-fiber image reversal device utilizes the principle of total internal reflection of optical fibers. The optical fibers constituting the device are produced using a rod-tube drawing process and vacuum control, consisting of a low-refractive-index cladding glass, a high-refractive-index core glass, and a light-absorbing glass. Thousands of micron-sized optical fiber filaments are then arranged in parallel and regularly, and thermally fused to form optical fiber plates. These raw optical fiber plates undergo subsequent cold-working processes such as rounding, cutting, and end-face polishing to create a high-resolution image transmission element. Because the optical fibers are tightly fused together by the cladding glass, adjacent fibers are very close together. Uneven cladding thickness can cause light to crosstalk between adjacent fibers, leading to light leakage as the input light penetrates the cladding during total internal reflection. Furthermore, poor anti-crystallization properties of the cladding glass can cause interfacial crystallization during fiber drawing, directly affecting the light transmission and image transmission performance. All of these factors are directly related to the cladding glass tube.

[0006] To meet the special manufacturing process requirements of fiber optic imaging elements, and to ensure that the cladding glass retains its inherent properties unchanged after multiple high-temperature drawing and pressing processes involving single filament, primary multifilament, secondary multifilament, and hot-melt pressing, it must possess excellent anti-crystallization properties, strong anti-crystallization ability, and good chemical stability. With the rapid development of low-light night vision in recent years, the production scale of ultra-narrow twisted-area fiber optic image reversers has been continuously expanding, and the application quantity and performance requirements have been gradually increasing. Consequently, the quantity, performance, and quality of the required cladding glass tubes have also been gradually improving. With the intensification of the production process for ultra-narrow twisted-area fiber optic image reversers, the stringent requirements for product quality, and fierce competition among companies, the demand for cladding glass materials with high requirements for anti-crystallization properties and strain point temperature is becoming increasingly urgent. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the prior art by providing a high-resolution, ultra-narrow twisted fiber optic image converter glass with excellent chemical properties, stable glass composition, low refractive index, and excellent anti-crystallization performance.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A composition of glass for a high-resolution, ultra-narrow twisted-wire fiber optic image inverter, comprising the following components in molar percentage:

[0010]

[0011] The present invention also provides a preferred technical solution, a composition of glass for a high-resolution ultra-narrow twisted fiber image inverter, comprising the following components in molar percentage:

[0012]

[0013]

[0014] The present invention also provides a more preferred technical solution, wherein a composition of glass for a high-resolution ultra-narrow twisted fiber image inverter comprises the following components in molar percentage:

[0015]

[0016] The present invention further provides a method for preparing high-resolution ultra-narrow twisted fiber image inverter glass using the aforementioned composition, comprising the following steps:

[0017] (1) Glass melting: Weigh the quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln for melting.

[0018] (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into the clarification pool. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool to be fully stirred and then flows into the material basin to cool down.

[0019] (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube.

[0020] (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace for annealing.

[0021] The glass melting temperature in the furnace is 1500-1600℃, and the melting time is 12-24 hours.

[0022] The glass clarification temperature in the clarification tank is 1400-1470℃, and the clarification and homogenization time is 4-6 hours.

[0023] The annealing temperature is 605-615℃.

[0024] The present invention further provides an application of the glass used in the high-resolution ultra-narrow twisted fiber optic image inverter as a skin glass in fiber optic image transmission elements.

[0025] In the glass composition for high-resolution ultra-narrow twisted fiber optic image inverters of this invention, SiO2 is the main component forming the glass skeleton and plays a major role in the glass skeleton. The molar percentage of SiO2 is 78.1-80.0 mol.%. When the SiO2 content is below 78.1 mol.%, it is difficult to obtain glass with a low refractive index, and it will also reduce the chemical stability of the glass. When the SiO2 content is above 80.0 mol.%, the high-temperature viscosity of the glass will increase, resulting in excessively high glass melting temperature, excessively high glass preparation cost, and is not conducive to glass production.

[0026] Al₂O₃ is an intermediate oxide of glass. 3+There are two coordination states in glass: located in tetrahedrons or octahedrons. When there is enough oxygen in the glass, aluminum-oxygen tetrahedra [AlO4] are formed, forming a continuous network with silicon-oxygen tetrahedra. When there is insufficient oxygen in the glass, aluminum-oxygen octahedrons [AlO6] are formed, which are the outer bodies of the network and are located in the cavities of the silicon-oxygen structure network. Therefore, within a certain content range, they can become the main body for forming the glass network, just like SiO2. The molar percentage of Al2O3 is 3.1-7.0 mol.%, preferably 3.5-6.5 mol.%, which is the main component for solving the problem of non-degradation of edge resolution in ultra-narrow twisted fiber image reversers. When the Al2O3 content is less than 3.1 mol.%, it will increase the brittleness of the glass and the strain point temperature of the glass will not be high enough, which is not conducive to the tensile deformation of the glass fiber and will reduce the edge resolution of the prepared ultra-narrow twisted fiber image reverser. When the Al2O3 content is greater than 7.0 mol.%, it will significantly increase the melting temperature of the glass and significantly increase the high-temperature viscosity of the glass, which is not conducive to the drawing and forming of optical fiber filaments and the control of fiber diameter.

[0027] B₂O₃ is a glass-forming oxide and a component of the glass framework. It also acts as a flux to reduce the viscosity of molten glass. Boron trigonal [BO₃] and boron-oxygen tetrahedron [BO₄] are structural components. Under different conditions, boron may exist as trigonal [BO₃] or boron-oxygen tetrahedron [BO₄]. At high-temperature melting conditions, it is generally difficult to form boron-oxygen tetrahedra, and it can only exist as trihedrons. However, at low temperatures, under certain conditions, boron… 3+ B₂O₃ tends to capture free oxygen to form tetrahedrons, resulting in a denser structure and increased low-temperature viscosity of the glass. However, due to its properties of decreasing glass viscosity at high temperatures and increasing it at low temperatures, and its role as a major component in reducing the glass's refractive index, the content range of B₂O₃ is relatively small. The molar percentage of B₂O₃ is 2.0-8.0 mol.%. Below 2.0 mol.%, it cannot act as a flux and reduces the chemical stability of the glass. Above 8.0 mol.%, it lowers the strain point temperature of the glass and prolongs its properties, which is detrimental to the drawing and shaping of optical fibers and the control of fiber diameter, while also increasing the tendency for phase separation in the glass.

[0028] Li2O is an alkali metal oxide and an outer oxide of the glass structure network. The molar percentage of Li2O is 0-1.0 mol.%, which mainly plays a role in reducing the viscosity of glass melting. If the content of Li2O is greater than 1.0 mol.%, it will increase the tendency of glass to crystallize.

[0029] Na₂O is an alkali metal oxide and an outer oxide of the glass structure network. The molar percentage of Na₂O is 0-2.9 mol.%. If the Na₂O content is greater than 2.9 mol.%, it will increase the refractive index and thermal expansion coefficient of the glass and increase the tendency of the glass to crystallize.

[0030] K2O is an alkali metal oxide and an outer oxide of the glass structure network. The molar percentage content of K2O is 5.1-10.0 mol.%, preferably 7.1-10.0 mol.%. If the K2O content is less than 5.1 mol.%, it will not play a role in regulating the viscosity of glass during high-temperature melting. If the K2O content is greater than 10.0 mol.%, it will increase the refractive index and thermal expansion coefficient of the glass, and increase the tendency of the glass to crystallize.

[0031] CaO is an alkaline earth metal oxide and a network oxide in glass structures. The molar percentage of CaO is 1.1-3.0 mol.%. If the CaO content is greater than 3.0 mol.%, it will reduce the chemical stability of the glass and increase the tendency of the glass to crystallize.

[0032] SrO is an alkaline earth metal oxide and an outer oxide of the glass structure network. The molar percentage of SrO is 0-1.0 mol.%. If the content of SrO is greater than 1.0 mol.%, it will reduce the chemical stability of the glass and increase the tendency of the glass to crystallize.

[0033] ZnO is used to lower the melting temperature of glass. The molar percentage of ZnO is 1.1-2.0 mol.%. If the ZnO content is greater than 2.0 mol.%, it will reduce the chemical stability of the glass and increase the refractive index and crystallization tendency of the glass.

[0034] TiO2 in molten glass exhibits the properties of Ti. 3+ and Ti 4+ Two valence states, typically Ti in silicate glasses. 4+ The valence state exists, but its 3d orbitals are empty, so "dd" transitions between electrons in the d orbitals cannot occur. Therefore, Ti... 4+ The valence state of Ti is colorless in glass; however, due to the fact that Ti... 4+ It strongly absorbs ultraviolet light, and its absorption band can usually enter the violet-blue part of the visible light region, causing the glass to actually appear brownish-yellow, especially Ti. 4+ It has the effect of enhancing the coloring of transition elements, so that even if the glass raw materials contain a small amount of transition elements, the resulting glass will still have a darker color. This effect is particularly obvious for iron. The molar percentage of TiO2 is 0-1.0%. TiO2 is used to adjust the refractive index and transmittance of glass. A TiO2 content greater than 1.0 mol.% will reduce the transmittance of glass and increase the refractive index.

[0035] CeO2 is a glass melting clarifying agent. The molar percentage of CeO2 is 0.05-0.2%. If the CeO2 content is greater than 0.2 mol%, it will reduce the transmittance of the glass and increase the tendency of the glass to crystallize.

[0036] MgF2 and CaF2 are used to adjust the refractive index and high-temperature viscosity properties of glass. The molar percentage of MgF2 is 0-2.0 mol.%, and a MgF2 content greater than 2.0 mol.% will increase the tendency of glass to crystallize. The content of CaF2 is 0.05-2.0 mol.%, and a CaF2 content greater than 2.0 mol.% will actually hinder the elimination of small bubbles in the molten glass and increase the tendency of glass to crystallize.

[0037] The glass of this invention belongs to silicate glass. It does not contain oxides of variable valence elements such as As2O3, PbO, BaO, and Fe2O3. Even if it contains a very small amount, it is due to the introduction of other glass raw materials. However, the content of these variable valence elements must be strictly controlled to below 1 ppm when introducing glass raw materials.

[0038] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are:

[0039] (1) It has a low refractive index, which is 1.48 to 1.51;

[0040] (2) The average linear thermal expansion coefficient in the range of 30 to 300℃ is (80±5)×10 -7 / ℃, the glass has a sufficiently long viscosity range, the strain point temperature of the glass is 580-620℃, and the expansion softening temperature of the low refractive index glass is 680-710℃.

[0041] (3) Low-refractive-index glass at 10 7.6 The temperature at which the viscosity of Poisson is reached is 780-810℃;

[0042] (4) The low-refractive-index glass does not crystallize or separate phase when kept at 850-900℃ for 6 hours, and has excellent anti-crystallization performance.

[0043] The glass of this invention has excellent chemical properties, stable glass composition, and low refractive index, making it suitable for use as the skin glass in the preparation of ultra-narrow twisted fiber image inverters. Furthermore, its high-temperature viscosity characteristics are suitable for mechanical tube drawing. Attached Figure Description

[0044] Figure 1 Viscosity fitting curves of low-refractive-index glass and fiber-core glass provided for embodiments of the present invention;

[0045] In the diagram: 1 represents fiber-core glass, and 2 represents low-refractive-index glass. Detailed Implementation

[0046] 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.

[0047] See Figure 1 The high-temperature viscosity fitting curves of low-refractive-index glass 2 and fiber-core glass 1 are shown at the torsional viscosity point 10. 7.6 The temperature at dPa.s must be the same to facilitate the compression of the twisted region in the fiber optic image reverter, thus enabling the fabrication of a high-resolution, ultra-narrow twisted region fiber optic image reverter. If both are at 10... 7.6 If the temperature at which the torsional viscosity point (dPa.s) differs or deviates significantly from its actual temperature, the edge resolution of the fabricated fiber image converter will decrease after compression and torsion, failing to achieve high resolution. Low-refractive-index glass at 10... 7.6 The temperature at which the viscosity reaches dPa.s is 780-810℃.

[0048] The corrugated glass tube composition provided by this invention is composed of a SiO2-Al2O3-B2O3-RO-R2O glass system. A certain amount of Al2O3 is introduced to increase the strain point temperature of the glass, thereby improving the tensile strength of the edge fibers after compression of the twisted region in the prepared ultra-narrow twisted fiber image converter. This ensures that the edge fibers of the ultra-narrow twisted fiber image converter do not break after compression in the twisted region, avoiding spot defects or reduced edge resolution. Alkali metal oxide RO and alkaline earth metal oxide R2O are introduced to improve the glass's anti-crystallization properties and high-temperature viscosity characteristics. CeO2 is introduced as a glass clarifying agent to eliminate internal bubbles in the glass. A certain amount of ZnO and TiO2 are introduced to adjust the viscosity of the glass. The multi-component oxide design effectively improves the glass's anti-crystallization properties. Simultaneously, a certain amount of fluoride is introduced to improve the glass's refractive index, ultimately resulting in a glass formulation that meets the requirements for preparing an ultra-narrow twisted fiber image converter.

[0049] In this document, all "mol.%" refers to the total molar amount of the final glass composition. The parameters, measurement methods, and instruments used for the glass used in the high-resolution ultra-narrow twisted fiber image inverter of this invention are as follows:

[0050] (1) Refractive index n D The refractive index of the glass at λ = 589.3 nm was determined using a refractive index meter.

[0051] (2) Average linear thermal expansion coefficient α at 30-300℃ 30 / 300 [×10 -7 [℃] was measured using a horizontal dilatometer, following the method specified in GB / T 16920-2015;

[0052] (3) The strain point temperature of the glass was measured using the bending beam method specified in GB / T 28196-2011.

[0053] The glass chemical composition (mol.%) of the examples is listed in detail in Table 1.

[0054] Table 1. Chemical composition (mol.%) and performance of glass examples for high-resolution ultra-narrow twisted fiber optic image reversers.

[0055]

[0056]

[0057] Example 1

[0058] According to the glass composition in Example 1 of Table 1, the raw materials are selected to ensure that the formulation meets the glass chemical composition requirements of Table 1. Then, low refractive index glass is prepared according to the following steps:

[0059] (1) Glass melting: Weigh the quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln and melt them at 1600℃ for 12 hours.

[0060] (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into a clarification pool at 1470℃ and is clarified and homogenized for 4 hours. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool and is stirred evenly. Then it flows into the material basin to cool down.

[0061] (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube.

[0062] (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace at 615℃ for annealing treatment.

[0063] Example 2

[0064] According to the glass composition in Example 2 of Table 1, the raw materials are selected to ensure that the formulation meets the glass chemical composition requirements of Table 1. Then, low refractive index glass is prepared according to the following steps:

[0065] (1) Glass melting: Weigh the quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln and melt them at 1500℃ for 24 hours.

[0066] (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into a 1430℃ clarification pool for clarification and homogenization for 6 hours. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool and is stirred evenly. Then it flows into the material basin to cool down.

[0067] (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube.

[0068] (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace at 610℃ for annealing treatment.

[0069] Example 3

[0070] According to the glass composition in Example 3 of Table 1, the raw materials are selected to ensure that the formulation meets the glass chemical composition requirements of Table 1. Then, low refractive index glass is prepared according to the following steps:

[0071] (1) Glass melting: Weigh the quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln and melt them at 1550℃ for 18 hours.

[0072] (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into a 1450℃ clarification pool for clarification and homogenization for 5 hours. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool and is stirred evenly. Then it flows into the material basin to cool down.

[0073] (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube.

[0074] (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace at 605℃ for annealing treatment.

[0075] Example 4

[0076] According to the glass composition in Example 4 of Table 1, the raw materials were selected to ensure that the formulation met the glass chemical composition requirements of Table 1. Then, low-refractive-index glass was prepared according to the following steps:

[0077] (1) Glass melting: Weigh the raw materials such as quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln to melt at 1560℃ for 16 hours.

[0078] (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into a 1450℃ clarification pool for clarification and homogenization for 4 hours. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool and is stirred evenly. Then it flows into the material basin to cool down.

[0079] (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube.

[0080] (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace at 610℃ for annealing treatment.

[0081] Example 5

[0082] According to the glass composition of Example 5 in Table 1, the raw materials are selected to ensure that the formulation meets the glass chemical composition requirements of Table 1. Then, low refractive index glass is prepared according to the following steps:

[0083] (1) Glass melting: Weigh the quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln and melt them at 1580℃ for 24 hours.

[0084] (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into a 1400℃ clarification pool for clarification and homogenization for 6 hours. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool and is stirred evenly. Then it flows into the material basin to cool down.

[0085] (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube.

[0086] (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace at 605℃ for annealing treatment.

[0087] The present invention also provides an application of glass prepared by mechanical tube drawing in optical fiber imaging elements.

[0088] The fiber optic image transmission element of this invention includes a fiber optic panel, a fiber optic image inverter, a fiber optic taper, and a fiber optic image transmission bundle, etc., and the cladding glass used is the low-refractive-index glass of this invention. The technical solution of this invention satisfies both the mechanical tube drawing and forming equipment process and the glass formulation and melting and forming process requirements for the cladding glass and its products of the fiber optic image transmission element. It improves upon the traditional, inefficient, costly, and low-quality manual material picking, blowing, and tube drawing method for fiber optic image transmission element cladding glass.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composition of glass for a high-resolution, ultra-narrow twisted-wire region fiber optic image reversing device, characterized in that, It consists of the following components in molar percentage:

2. The composition according to claim 1, characterized in that, It consists of the following components in molar percentage:

3. A method for preparing high-resolution ultra-narrow twisted-wire region fiber optic image reversing glass using the composition according to claim 1 or 2, characterized in that, Includes the following steps: (1) Glass melting: Weigh the quartz sand, aluminum hydroxide, boric acid or boric anhydride, lithium carbonate, sodium carbonate, potassium carbonate or potassium nitrate, calcium carbonate, strontium carbonate, zinc oxide, titanium dioxide, cerium oxide, magnesium fluoride and calcium fluoride according to the batching requirements, mix them evenly, and then put them into the glass melting pool in the kiln for melting. (2) Clarification and homogenization: After the raw materials are melted into the glass melt, the glass melt flows from the glass melt pool into the clarification pool. After the glass melt is clarified and homogenized to remove and absorb small bubbles, the glass melt flows into the stirring pool to be fully stirred and then flows into the material basin to cool down. (3) Tube forming: After the glass melt cools down, the glass melt flows from the material basin to the feed channel and then to the forming nozzle. After passing through the forming nozzle, the glass melt is pulled by the tube forming machine to form a uniform glass tube. (4) Cutting and annealing: Cut the drawn glass tube to a certain length as required, and then put the cut glass tube into an annealing furnace for annealing.

4. The method according to claim 3, characterized in that, The glass melting temperature in the furnace is 1500-1600℃, and the melting time is 12-24 hours.

5. The method according to claim 4, characterized in that, The glass clarification temperature in the clarification tank is 1400-1470℃, and the clarification and homogenization time is 4-6 hours.

6. The method according to claim 5, characterized in that, The annealing temperature is 605-615℃.

7. A glass for a high-resolution, ultra-narrow twisted-wire region fiber optic image inverter, characterized in that, Prepared according to the method described in any one of claims 3-6.

8. The glass for a high-resolution ultra-narrow twisted fiber optic image reversing device according to claim 7, characterized in that, The glass has a refractive index of 1.48–1.51 and an average linear thermal expansion coefficient of (80±5)×10⁻⁶ in the temperature range of 30–300℃. -7 / ℃, the strain point temperature of the glass is 580-620℃, the expansion softening temperature of the glass is 680-710℃, and the glass is at 10 7.6 The viscosity is dPa.s at a temperature of 780-810℃, and the glass does not crystallize or separate into phases when held at 850-900℃ for 6 hours.

9. The application of the glass described in claim 7 or 8 as the skin glass in an optical fiber image reversal device for high resolution ultra-narrow twisted area fiber optic image transmission elements.

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