Optical fiber image inverter with ultra-narrow twisted fiber area and preparation method therefor and application thereof, and related composition

Abstract

The present application belongs to the field of optical fiber image transmission element manufacturing. Disclosed are a preparation method for an optical fiber image inverter with an ultra-narrow twisted fiber area, and the application thereof, which solve the problem of it being difficult to prepare an optical fiber image inverter with an ultra-narrow twisted fiber area. The preparation method comprises: drawing a glass rod having a low refractive index and a high strain point temperature to form cladding fibers; drawing a glass rod having a high refractive index and a high transmittance to form filling glass fibers, and then performing drawing to form jacket absorption fibers; evenly wrapping the cladding fibers around the outer side of a cladding glass tube, and then, after matching a fiber-core glass rod with the cladding glass tube, performing drawing to form single fibers; and then sequentially preparing primary composite fibers and secondary composite fibers, and performing hot-melt compression molding and twist molding, wherein the width of a heating element of a heating furnace for ultra-narrow high-temperature area twist molding is 3-4 mm, the distance between the heating element of the heating furnace and the surface of an optical fiber image inverter blank is 1.0-2.5 mm, and the twist molding time is 2-9 minutes. The prepared optical fiber image inverter with an ultra-narrow twisted fiber area has high resolution, high contrast and clear imaging, and is applied to low-light-level image intensifiers.

Description

An ultra-narrow twisted-wire region optical fiber image invertor, its preparation method and application, and related compositions

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 24, 2023, with application number 202311579576.3 and invention name “A preparation method and application of an ultra-narrow twisted fiber region optical fiber image inverter”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of manufacturing optical fiber image transmission components, and in particular to a preparation method and application of an ultra-narrow twisted fiber region optical fiber image inverter. Background Art

[0004] Night combat capability has become a crucial indicator of troop capabilities in modern high-tech warfare. Helmet-mounted night vision devices (HMDs) were developed to help soldiers adapt to the increasingly complex nighttime combat environment and achieve earlier detection and clearer visibility of targets in all-weather operations. Helmet-mounted night vision devices, consisting of low-light-level night vision devices mounted on helmets, are primarily used by pilots, night pilots, and special forces personnel, and have become a vital piece of equipment for soldiers. Helmet-mounted night vision devices enable pilots to observe the surrounding environment in low-light conditions, providing a wider field of view and enabling helicopter pilots to fly close to the ground even in low-light conditions. However, mounting the device on the front of the pilot's standard flight helmet shifts the combined center of gravity of the device, helmet, and head forward and upward from the normal center of gravity. The added weight of the device and its mounting bracket, and the resulting shift in center of gravity, imposes an additional burden on the pilot, leading to fatigue during routine flight and potentially causing neck injuries during sudden maneuvers. Some systems install a counterweight or night vision goggle battery on the back of the helmet to partially correct for center of gravity shifts, but this increases the total weight borne by the head and restricts head movement within the helmet, significantly reducing the pilot's potential field of view. Furthermore, helmet-mounted night vision goggles, due to their excessive mass, unstable center of gravity, increased profile, limited noise immunity, and poor comfort, have become a significant factor affecting pilot health and flight safety. Wearing a flight helmet for extended periods can easily lead to excessive head and neck load, high thermal load, hearing loss, visual impairment, and increased psychological stress, exacerbating flight fatigue. In severe cases, this can directly impact the pilot's operational proficiency and threaten flight safety. Especially after prolonged wear, neck pain, hearing loss, high thermal load, and poor comfort can easily occur, further exacerbating pilot fatigue. This can lead to decreased coordination, unstable movement force, difficulty in skillfully and accurately completing flight maneuvers, and a significant increase in the incidence of human error. In order to continue to maintain the advantages of night vision technology and adapt to the overall requirements of high-mobility operations of troops, helmet night vision devices are constantly developing in the direction of miniaturization, lightweight and integration. The goal is to reduce the size and weight, make the objective lens and eyepiece protrude less, bring the center of gravity closer to the face, increase the field of view, and increase the visibility, making it more suitable for long-term head-mounted use.

[0005] The fiber optic image invertor (FII) is a core optical component in helmet-mounted night vision devices (HMDs). It is a high-performance optoelectronic imaging device with a large numerical aperture, high light transmission efficiency, high resolution, and clear, true-to-life images. Optically, it features zero thickness, a simple structure, compact size, light weight, excellent airtightness, minimal distortion, reduced speckle, low interstage coupling loss, and high coupling efficiency, which improves edge image quality. As the optical output window of low-light-level image intensifiers, it plays a vital role in improving the quality of imaging devices and is a cutting-edge high-tech product in the global optoelectronics industry. To meet the growing demand for miniaturization and lightweighting, as well as improved resolution and image clarity, there has been a desire to reduce the height, size, and weight of the FIII to reduce the overall weight and volume of HMDs. Research has shown that if the weight of the FIII can be reduced by 30%, the overall weight of the associated HMD structures, components, and battery systems could be reduced by over 50%. This significantly improves soldiers' flexibility and mobility during combat and plays a crucial role in enhancing troops' nighttime combat capabilities. Therefore, the development of an ultra-narrow twisted fiber image inverter has become an urgent need to meet the miniaturization and lightweight requirements of helmet night vision goggles.

[0006] The ultra-narrow twisted zone optical fiber image inverter is prepared by compressing the twisted zone of the optical fiber image inverter. Compared with the normal optical fiber image inverter, the height and weight are significantly reduced. However, the compression of the twisted zone of the normal optical fiber image inverter will cause the edge fibers of the optical fiber image inverter to stretch and deform more seriously, and slippage will occur between the optical fibers. In particular, the skin thickness of the edge optical fibers will stretch and thin. Since the optical fiber is completely tightly fused together by the skin glass, the adjacent optical fibers are very close, and the compression of the skin glass in the twisted zone will cause uneven fiber stretching and deformation, so that the incident light entering the optical fiber core glass will cross-link in the skin between adjacent fibers, causing the input light to penetrate the skin during the total reflection process and penetrate, resulting in the disappearance of the total reflection mechanism of the edge optical fiber, which directly affects the light transmission and image transmission performance of the optical fiber, causing the ultra-narrow twisted zone optical fiber image inverter to have problems such as loss of edge resolution, decreased transmittance, reduced contrast, and distortion of image transmission. In particular, as the twisted wire zone of the optical fiber image inverter is compressed shorter, it will bring great difficulties to the preparation process of the ultra-narrow twisted wire zone image inverter. During the preparation process, not only the edge resolution must be considered, but also the matching of materials in the process, the mutual diffusion of components, etc., must be considered. Therefore, the preparation of the ultra-narrow twisted wire zone optical fiber image inverter is very difficult.

[0007] Summary of the Invention

[0008] In order to solve the problems existing in the prior art in preparing ultra-narrow twisted fiber image inverters, the present application provides a method for preparing ultra-narrow twisted fiber image inverters with high resolution, high contrast and clear imaging.

[0009] The technical solution adopted by this application to solve the above problems is:

[0010] A method for preparing an ultra-narrow twisted fiber image inverter comprises the following steps:

[0011] (1) Cone wire drawing: a round glass rod with low refractive index and high strain point temperature is drawn into a cone wire;

[0012] The main purpose of drawing the confined tube wire is to increase the strain point temperature of the glass and enhance the drawing strength of the optical fiber's cortex, making it less likely for the cortex to be damaged during the preparation of the ultra-narrow twisted wire zone image inverter, thereby ensuring the total reflection structure of the optical fiber.

[0013] The diameter of the drawn tube wire can be selected from Φ1.6mm to Φ2.0mm. If the wire diameter is less than Φ1.6mm, the purpose of enhancing the drawing strength of the optical fiber cortex cannot be achieved. If the wire diameter is greater than Φ2.0mm, the cortex thickness of the optical fiber will be thickened, resulting in more useless light flux and reducing the contrast and transmittance of the optical fiber image inverter.

[0014] (2) Filled glass filament drawing: Drawing a glass rod with high refractive index and high transmittance into a triangular filled glass filament; the purpose of filling glass filament is mainly to strengthen the internal structure of the optical fiber and increase the filling coefficient, so that the ultra-narrow twisted fiber area image inverter does not slip during the preparation process, while increasing the transmission of effective light flux.

[0015] (3) Drawing of sheathed absorbent wire: light absorbing glass with good light absorption performance is prepared into light absorbing glass rod, and then the light absorbing glass rod is matched with a leather glass tube, and then drawn into a sheathed absorbent wire; the light absorbing wire is drawn into a leather glass tube in order to reduce the diffusion of the light absorbing material and improve the optical uniformity of the internal structure of the optical fiber.

[0016] (4) Monofilament drawing: The surrounding tube wire is evenly wrapped around the outside of the skin glass tube, and then the high-refractive index core glass rod and the skin glass tube after the wire are matched and then the monofilament is drawn to obtain the drawn monofilament. The diameter of the monofilament can be selected from Φ2.4mm to Φ4.20mm; if the diameter of the monofilament is less than 2.4mm, the triangular pores of the arranged primary composite rod are too small, which is not conducive to the insertion and filling of the filling glass wire; if the diameter of the monofilament is greater than 4.2mm, the roundness uniformity of the drawn monofilament is difficult to control, and the structure of the arranged primary composite rod is prone to loose wires and cracks. Therefore, according to the size of the diameter of the drawn monofilament, the filling glass wire drawn in step 2 can be selected as a triangular filling glass wire; the height of the filling glass wire can be selected from 0.50 to 0.95mm.

[0017] (5) Drawing of a primary multifilament: Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross section, wherein the number of monofilaments on each side of the primary multifilament rod is N, and the total number of monofilaments in the arranged primary composite rod is (3N(N-1)+1), and replacing the monofilament arranged in the center of the primary composite rod with the sleeve absorption wire, and the diameter of the replaced monofilament is the same as that of the replaced sleeve absorption wire; and inserting the filling glass wire into the triangular pores of the primary composite rod; drawing the primary composite rod completed by the above combination into a primary multifilament, and the size of the hexagonal opposite sides of the primary multifilament can be selected to be 1.10mm to 1.30mm;

[0018] In the primary composite rod after the replacement, the number of monofilaments on each side of the primary multifilament rod is 8 ≥ N ≥ 3. If the number of monofilaments on each side is less than 3, the internal structure gap is too large, resulting in an increase in useless light flux, causing the prepared optical fiber image inverter to exhibit fixed pattern noise defects. If the number of monofilaments on each side exceeds 8, the primary composite rod is too coarse, and the internal structure is prone to the risk of fiber cracking and fiber unraveling, making it difficult to control the density of the internal fiber structure, and the prepared optical fiber image inverter will exhibit grid and spot defects. The number of monofilaments N per side can be 6.

[0019] (6) Drawing of secondary multifilaments: Arrange the drawn primary multifilaments into secondary composite rods with a regular hexagonal cross section, draw the secondary composite rods into secondary multifilaments, and cut the drawn secondary multifilaments into fixed lengths and arrange them into screen plate segments; the hexagonal opposite side dimensions of the secondary multifilaments are 0.86-1.06 mm.

[0020] (7) Hot melt pressing: placing the screen plate segment into a hot melt pressing mold, and then placing the hot melt pressing mold into a hot melt pressing furnace, and hot melt pressing is performed according to the designed compression ratio before and after hot melt pressing of the plate segment. After hot melt pressing, the fiber optic image invertor blank plate segment is obtained;

[0021] (8) Twisting forming: The fiber optic image inverter blank is cut, rounded, and ground to prepare a fiber optic image inverter blank. The fiber optic image inverter blank is twisted at an angle of 180° in an ultra-narrow high-temperature zone twisting forming furnace to prepare an ultra-narrow twisted fiber optic image inverter;

[0022] The width of the heating element of the heating furnace in the ultra-narrow high-temperature zone is 3 to 4 mm; if the width of the heating element is less than 3 mm, the temperature and heating power required for the twisting molding of the optical fiber inverter cannot be achieved; if the width of the heating element is greater than 4 mm, the ultra-narrow twisted wire zone inverter cannot be produced.

[0023] The distance between the heating element of the heating furnace in the ultra-narrow high-temperature zone and the surface of the optical fiber inverter blank is 1.0 to 2.5 mm. If the distance is less than 1.0 mm, it is easy to cause the surface to overheat, and the edge transmittance of the prepared inverter will decrease; if the distance is greater than 2.5 mm, the heating zone will become wider, and it will be difficult to prepare an ultra-narrow twisted wire zone inverter.

[0024] The twisting molding time of the optical fiber image inverter blank for twisting 180° is 2 to 9 minutes. If the twisting time is less than 2 minutes, the surface temperature of the image inverter blank will be too high, and the edge transmittance will easily decrease. If the twisting time exceeds 9 minutes, the edge resolution of the ultra-narrow twisted wire area image inverter will be reduced.

[0025] The ultra-narrow twisted fiber image inverter prepared by the preparation method of the present application has an overall height of no more than 15 mm and a weight of less than 20 g; the unit fiber diameter of the ultra-narrow twisted fiber image inverter is ≤4.0 μm; the center resolution of the ultra-narrow twisted fiber image inverter is greater than 140 lp / mm, and the edge resolution is greater than 110 lp / mm; the ultra-narrow twisted fiber image inverter has a light crosstalk of less than 1.0% at a distance of 0.1 mm from the blade; the ultra-narrow twisted fiber image inverter has excellent light transmittance, with a transmittance of >70% in the wavelength range of 400-700 nm; the ultra-narrow twisted fiber image inverter has excellent fixed pattern noise performance, and no obvious multifilament boundary is observed under a 10x microscope.

[0026] The present application also provides the application of the ultra-narrow twisted fiber image invertor in a low-light-level image intensifier.

[0027] The composition of the confined tube filaments is composed of the following components in molar percentage:

[0028] The composition of the confined tube filaments is composed of the following components in molar percentage:

[0029] The glass composition of the surrounding tube filament of the skin glass tube provided in the present application 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 of the prepared ultra-narrow twist zone optical fiber image inverter after the twist zone is compressed, ensuring that the edge fibers of the ultra-narrow twist zone optical fiber image inverter are not damaged after compression in the twist zone, avoiding the generation of spot defects or reduced edge resolution; alkali metal oxide RO and alkaline earth metal oxide R2O are introduced to improve the anti-devitrification performance and high-temperature viscosity characteristics of the glass; and CeO2 is introduced as a glass clarifier to eliminate bubbles inside the glass; a certain amount of ZnO and TiO2 are introduced to adjust the viscosity of the glass. The design of multi-component oxides can effectively improve the anti-devitrification performance of the glass; and a certain amount of fluoride is introduced to improve the refractive index of the glass, ultimately obtaining a glass formula that meets the requirements for preparing ultra-narrow twist zone optical fiber image inverters.

[0030] The refractive index of the glass of the surrounding tube is 1.48 to 1.51; the average linear thermal expansion coefficient in the range of 30 to 300°C is (80±5)×10 -7 / ℃, has a sufficiently long viscosity range, the strain point temperature of the glass of the surrounding tube wire is 580-620 ℃, the expansion softening temperature of the glass of the surrounding tube wire is 680-710 ℃, the glass of the surrounding tube wire is 10 7.6 The viscosity of the fiber is 10 dPa.s at a temperature of 780-810 ° C. It does not crystallize or separate at 850-900 ° C for 6 hours, and has excellent anti-crystallization performance. 7.6 The temperature at the torsional viscosity point of 0.05 dPa.s is the same, which is beneficial to the compression of the twisted wire area of ​​the optical fiber image inverter, and the edge resolution will not be reduced after the twisted wire area is compressed.

[0031] In the glass composition of the surrounding tube yarn of this application, SiO2 is the main component that forms the glass skeleton and plays a major role in the glass framework. The molar percentage of SiO2 is 78.1-80.0 mol%. A SiO2 content below 78.1 mol% makes it difficult to obtain low-refractive-index glass and reduces the glass's chemical resistance. A SiO2 content above 80.0 mol% increases the glass's high-temperature viscosity, resulting in excessively high glass melting temperatures and production costs, which is detrimental to glass production.

[0032] Al2O3 is an intermediate oxide of glass. 3+There are two coordination states in glass, namely, located in tetrahedron or octahedron. When there is enough oxygen in the glass, aluminum oxide tetrahedron [AlO4] is formed, forming a continuous network with silicon oxide tetrahedron. When there is insufficient oxygen in the glass, aluminum oxide octahedron [AlO6] is formed, which is an external body of the network and is located in the hole of the silicon oxide structure network. Therefore, within a certain content range, it can become the main body of glass network formation like SiO2. The molar percentage of Al2O3 is 3.1-7.0 mol.%, and can be optionally 3.5-6.5 mol.%. Al2O3 can significantly increase the strain point temperature of the glass material and is the main component for solving the problem of not reducing the edge resolution of the ultra-narrow twisted fiber image inverter. When the Al2O3 content is lower than 3.1 mol.%, the brittleness of the glass will increase, 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 inverter; when the Al2O3 content is greater than 7.0 mol.%, the melting temperature of the glass will be significantly increased, and the high-temperature viscosity of the glass will be significantly increased, causing the monofilament to be elliptical during drawing, and the roundness of the monofilament cannot be controlled, which is not conducive to the drawing and forming of the optical fiber and the control of the fiber diameter size.

[0033] B2O3 is a glass-forming oxide and a component of the glass skeleton. It is also a flux that reduces the viscosity of the glass. Boron oxide triangles [BO3] and boron oxide tetrahedrons [BO4] are structural components. Boron may exist in the form of triangles [BO3] or boron oxide tetrahedrons [BO4] under different conditions. Under high-temperature melting conditions, it is generally difficult to form boron oxide tetrahedrons and can only exist in the form of trihedrons. However, at low temperatures, under certain conditions, B 3+ B2O3 tends to capture free oxygen to form tetrahedra, compacting the structure and increasing the 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 being the primary component that reduces the glass's refractive index, the B2O3 content range is relatively small. The molar percentage of B2O3 is 2.0-8.0 mol%. Below 2.0 mol%, B2O3 fails to act as a flux and reduces the chemical stability of the glass. A B2O3 content greater than 8.0 mol% lowers the strain point temperature and prolongs the glass's grit, hindering optical fiber drawing and fiber diameter control, while also increasing the glass's tendency to phase separate.

[0034] Li2O is an alkali metal oxide and an external oxide of the glass structure network. The molar percentage of Li2O is 0-1.0 mol%. It mainly plays the role of reducing the viscosity of the molten glass. When the content of Li2O is greater than 1.0 mol%, it will increase the crystallization tendency of the glass.

[0035] Na2O is an alkali metal oxide and an external oxide of the glass structure network. The molar percentage of Na2O is 0-2.9 mol%. When the content of Na2O is greater than 2.9 mol%, it will increase the refractive index and thermal expansion coefficient of the glass and increase the crystallization tendency of the glass.

[0036] K2O is an alkali metal oxide and an external oxide of the glass structure network. The molar percentage of K2O is 5.1-10.0 mol%. 7.1-10.0 mol% can be selected. If the content of K2O is less than 5.1 mol%, it will not play a role in regulating the high-temperature melting viscosity of the glass. If the content of K2O is greater than 10.0 mol%, it will increase the refractive index and thermal expansion coefficient of the glass and increase the crystallization tendency of the glass.

[0037] CaO is an alkaline earth metal oxide and a network oxide of the glass structure. 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 crystallization tendency of the glass.

[0038] SrO is an alkaline earth metal oxide and an external oxide of the glass structure network. The molar percentage of SrO is 0-1.0 mol%. If the SrO content is greater than 1.0 mol%, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0039] 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 resistance of the glass and increase the refractive index and crystallization tendency of the glass.

[0040] TiO2 in the glass melt presents Ti 3+ and Ti 4+ There are two valence states, usually Ti in silicate glass 4+ The valence state exists, and its 3d orbital is empty, and the "dd" transition between electrons in the d orbital cannot occur, so Ti 4+ The valence state appears colorless in glass, however, due to the Ti 4+ It can strongly absorb ultraviolet rays, and its absorption band can usually enter the purple-blue part of the visible light region, causing the glass to actually appear brownish yellow, especially Ti 4+ It enhances the coloring of transition elements, resulting in a darker color even when the raw glass contains small amounts of these elements. This effect is particularly pronounced with 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% reduces the transmittance and increases the refractive index of the glass.

[0041] CeO2 is a glass melting clarifier. 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 crystallization tendency of the glass.

[0042] MgF2 and CaF2 are used to adjust the refractive index and high-temperature viscosity characteristics of the glass. The molar percentage of MgF2 is 0-2.0 mol%. A MgF2 content greater than 2.0 mol% will increase the crystallization tendency of the glass; the CaF2 content is 0.05-2.0 mol%. A CaF2 content greater than 2.0 mol% is not conducive to the elimination of small bubbles in the glass liquid and will increase the crystallization tendency of the glass.

[0043] The surrounding tube wire glass of the present application is a silicate glass. The glass does not contain oxides of variable valence elements such as As2O3, PbO, BaO, Fe2O3, etc. Even if it contains extremely small amounts, they are introduced from other glass raw materials. However, when introducing the glass raw materials, the content of these variable valence elements must be strictly controlled below 1ppm.

[0044] An ultra-narrow twisted-wire-area optical fiber image inverter is prepared by setting a surrounding tube wire on the periphery of the cortical glass tube. The optical fiber image inverter has the characteristics of high viscosity and high strain point temperature. The edge resolution of the ultra-narrow twisted-wire-area optical fiber image inverter does not decrease, the spot defects are few, and the edge resolution and transmittance uniformity are good.

[0045] The glass of the surrounding tube is composed of different materials than the glass tube covering, and the strain point temperature of the surrounding tube is significantly higher than that of the glass tube covering. This helps to enhance the tensile strength of the optical fiber's cortex, making it less susceptible to breakage after compression in the twisting zone, while also ensuring the optical fiber's total internal reflection structure.

[0046] The glass of the surrounding tube filament and the glass of the core glass rod are 10 7.6 dPa.s torsional viscosity point at the same temperature, so that it is conducive to the compression of the twisted wire area of ​​the optical fiber image inverter, and to prepare an ultra-narrow twisted wire area optical fiber image inverter with qualified performance indicators. 7.6 dPa.s when the torsional viscosity point is different or the torsional viscosity point temperature deviates far, then the edge resolution of the prepared optical fiber image inverter will be reduced after the compression torsion zone, and the edge resolution cannot be greater than 110lp / mm.

[0047] The glass-filled composition consists of the following components in mole percentage:

[0048] The glass-filled composition consists of the following components in mole percentage:

[0049] The present application also provides a glass composition for filling glass fibers inserted into the pores of a primary composite rod. The glass composition has a refractive index of 1.80 to 1.82 and an average linear thermal expansion coefficient of (90±5)×10 -7 / ℃, the strain point temperature of the glass filled with glass wool is 610-630℃, the transmittance of the glass in the spectrum of 400-700nm is greater than 95%, the glass does not crystallize or phase separate when kept warm at 850-900℃ for 6 hours, and has excellent anti-crystallization performance.

[0050] In the glass-filled fiber composition of this application, SiO2 forms the main component of the glass framework and plays a major role in the glass structure. The molar percentage (mol%) of SiO2 is 15.0-25.0. A SiO2 content below 15.0 mol% makes it difficult to obtain a high-refractive-index glass and reduces the glass's chemical resistance. When the SiO2 content exceeds 25.0 mol%, the high-temperature viscosity of the glass increases, causing the glass melting temperature to be too high, and the thermal expansion coefficient of the glass decreases.

[0051] Al2O3 is an intermediate oxide of glass. 3+ Glass has two coordination states: tetrahedral and octahedral. When the glass contains sufficient oxygen, aluminum oxide tetrahedra (AlO4) form, forming a continuous network with silicon oxide tetrahedra. When the glass contains insufficient oxygen, aluminum oxide octahedra (AlO6) form, acting as network externalities within the cavities of the silicon oxide network. Therefore, within a certain content range, Al2O3 can serve as the main component of the glass network, similar to SiO2. The molar percentage of Al2O3 is 0-0.5 mol%, with an optional range of 0.1-0.5 mol%. When the Al2O3 content exceeds 0.5 mol%, the melting temperature of the glass is significantly increased, along with the high-temperature viscosity.

[0052] B2O3 is a glass-forming oxide and a component of the glass skeleton. It is also a flux that reduces the viscosity of the glass. Boron oxide triangles [BO3] and boron oxide tetrahedrons [BO4] are structural components. Boron may exist in the form of triangles [BO3] or boron oxide tetrahedrons [BO4] under different conditions. Under high-temperature melting conditions, it is generally difficult to form boron oxide tetrahedrons and can only exist in the form of trihedrons. However, at low temperatures, under certain conditions, B 3+It tends to capture free oxygen to form tetrahedra, compacting the structure and increasing the low-temperature viscosity of the glass. However, due to its characteristic of decreasing glass viscosity at high temperatures and increasing it at low temperatures, it is also the primary component that reduces the glass's refractive index. The molar percentage (mol%) of B2O3 is 20.0-30.0. Below 20.0 mol%. B2O3 content will not function as a flux and will reduce the chemical stability of the glass. A B2O3 content greater than 30.0 mol% will reduce the glass's refractive index and increase its tendency to phase separation.

[0053] MgO is an oxide outside the glass structure network. The molar percentage (mol.%) of MgO is 1.01-2.0. If the MgO content is greater than 2.0 mol.%, it will reduce the chemical resistance of the glass and increase the thermal expansion coefficient of the glass.

[0054] SrO is an oxide outside the glass structure network. The molar percentage (mol.%) of SrO is 1.0-5.0. If the SrO content is greater than 5.0 mol.%, it will reduce the chemical resistance of the glass and increase the thermal expansion coefficient of the glass.

[0055] BaO is an external oxide in the glass structure network and can effectively increase the refractive index of the glass. The molar percentage (mol.%) of BaO is 15.0-25.0. When the BaO content is less than 15.0 mol.%, the refractive index of the glass will be significantly reduced. When the BaO content is greater than 25.0 mol.%, the crystallization temperature of the glass will be increased, the crystallization tendency of the glass will be increased, and the density of the glass will be significantly increased.

[0056] ZnO is an oxide that regulates the glass melting temperature and the glass crystallization performance. The molar percentage (mol.%) of ZnO is 0.5-2.0. A ZnO content greater than 2.0 mol.% will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0057] SnO2 is a glass clarifier. The molar percentage (mol.%) of SnO2 is 0.1-0.2. When the content of SnO2 is greater than 0.2 mol.%, the crystallization tendency of the glass will increase.

[0058] TiO2 is used to increase the refractive index and transmittance of glass. The molar percentage (mol.%) of TiO2 is 5.0-9.0. If the content of TiO2 is greater than 9.0 mol.%, the transmittance of the glass will be reduced.

[0059] WO3 is an oxide used to adjust the crystallization performance of glass. The molar percentage (mol.%) of WO3 is 1.0-5.0. A WO3 content greater than 5.0 mol.% will increase the crystallization tendency of the glass.

[0060] 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.%, the thermal expansion coefficient of the glass will increase.

[0061] 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. However, when the Nb2O5 content is greater than 5.0 mol.%, the density and thermal expansion coefficient of the glass will increase.

[0062] Y2O3 is a lanthanide rare earth oxide that can increase the refractive index of glass and is also an oxide 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.%, the thermal expansion coefficient of the glass will increase.

[0063] 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. However, when the Ta2O5 content is greater than 5.0 mol.%, the density and thermal expansion coefficient of the glass will increase.

[0064] Gd2O3 is also a rare earth oxide that can increase the refractive index of glass and 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 0.9mol.%, the density and thermal expansion coefficient of the glass will increase.

[0065] The filling glass fibers optionally inserted into the triangular pores of the present application are triangular in shape. The triangular filling glass fibers can prevent the internal fiber structure of the ultra-narrow twisted fiber image inverter from sliding or deflecting, thereby maintaining the stable total reflection structure of the optical fiber and significantly increasing the useful light flux incident on the optical fiber, thereby improving the transmittance and transmittance uniformity of the ultra-narrow twisted fiber image inverter.

[0066] The filler glass is made of a different material than the core glass, and its strain point temperature is significantly higher than that of the core glass. This helps enhance the stability of the image invertor's internal structure, making it less susceptible to fiber slippage and deformation after compression in the twisting zone, thereby ensuring the optical fiber's total internal reflection.

[0067] The composition of the light absorbing glass is composed of the following components in molar percentage:

[0068] The composition of the light absorbing glass is composed of the following components in molar percentage:

[0069] Since the wavelength of the phosphor used in the fluorescent screen of the low-light-level night vision device is in the range of 510-560nm, mainly green wavelength, the light absorbing material glass of the present application has strong and uniform light absorption capacity and spectral absorption effect in the wavelength range of 510-660nm at a thickness of 0.5±0.01mm, and the spectral transmittance is ≤3.0%, which has good contrast performance adjustment of the optical fiber inverter; it has similar thermal expansion coefficient and viscosity characteristics to the skin glass, and the thermal expansion coefficient of the light absorbing material glass is (85±5)×10 -7 / ℃; it has good chemical stability and anti-crystallization performance. The light-absorbing glass does not crystallize or separate when kept at 850-900℃ for 6 hours. It has excellent anti-crystallization performance and excellent chemical stability.

[0070] In the light-absorbing glass composition of this application, SiO2 forms the main component of the glass framework and plays a major role in the glass structure. The molar percentage (mol%) of SiO2 is 71.0-80.0. A SiO2 content below 71.0 mol% makes it difficult to achieve a thermal expansion coefficient similar to that of the raw material glass and also reduces the chemical stability of the glass. When the SiO2 content exceeds 80.0 mol%, the high-temperature viscosity of the glass increases, resulting in excessively high glass melting temperatures.

[0071] Al2O3 is an intermediate oxide of glass. 3+ There are two coordination states: located in tetrahedra or octahedra. When there is sufficient oxygen in the glass, aluminum oxide tetrahedra [AlO4] are formed, forming a continuous network with silicon oxide tetrahedra. When there is insufficient oxygen in the glass, aluminum oxide octahedra [AlO6] are formed, which are external to the network and located in the cavities of the silicon oxide network. Therefore, within a certain content range, it can form the main component of the glass network with SiO2. The molar percentage (mol.%) of Al2O3 is 0.5-5.0. An Al2O3 content greater than 5.0 mol.% will significantly increase the high-temperature viscosity of the glass, causing the glass to melt at a higher temperature.

[0072] B2O3 is a glass-forming oxide and a component of the glass skeleton. It is also a flux that reduces the viscosity of the glass. Boron oxide triangles [BO3] and boron oxide tetrahedrons [BO4] are structural components. Boron may exist in the form of triangles [BO3] or boron oxide tetrahedrons [BO4] under different conditions. Under high-temperature melting conditions, it is generally difficult to form boron oxide tetrahedrons and can only exist in the form of trihedrons. However, at low temperatures, under certain conditions, B 3+It tends to capture free oxygen to form tetrahedra, compacting the structure and increasing the low-temperature viscosity of the glass. However, due to its properties of lowering the viscosity of glass at high temperatures and increasing it at low temperatures, it is also the primary component that lowers the refractive index of glass, which dictates a relatively small content range. The molar percentage (mol%) of B2O3 ranges from 1.0 to 5.0. A B2O3 content greater than 5.0 mol% increases the tendency of the glass to separate.

[0073] Na2O is an oxide outside the glass structure network. The molar percentage (mol.%) of Na2O is 1.0-11.0. When the content of Na2O is greater than 11.0 mol.%, the thermal expansion coefficient of the glass will increase.

[0074] K2O is an oxide outside the glass structure network. The molar percentage (mol.%) of K2O is 6.0-11.0. When the content of K2O is greater than 11.0 mol.%, the thermal expansion coefficient of the glass will increase.

[0075] MgO is an oxide outside the glass structure network and is used to adjust the crystallization temperature of the glass. The molar percentage (mol.%) of MgO is 0.1-2.0. When the MgO content is greater than 2.0 mol.%, the crystallization tendency of the glass will increase.

[0076] CaO is an oxide outside the glass structure network. The molar percentage (mol.%) of CaO is 0.1-2.0. If the CaO content is greater than 2.0 mol.%, the chemical stability of the glass will be reduced and the crystallization tendency of the glass will be increased.

[0077] BaO is an external oxide in the glass structure network and is used to adjust the crystallization temperature of the glass. The molar percentage (mol.%) of BaO is 0-0.04. A BaO content greater than 0.04 mol.% will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0078] TiO2 is used to adjust the chemical resistance and crystallization of glass. The molar percentage (mol.%) of TiO2 is 0-1.0. A TiO2 content greater than 1.0 mol.% will reduce the chemical resistance of the glass and increase the tendency to crystallize.

[0079] Co2O3 is a colorant in light-absorbing glass. The molar percentage (mol%) of Co2O3 is 0.1-0.4. Co2O3 has a lower melting point than CoO, allowing it to combine with other coloring ions to form a stable form in the glass, thus making the light-absorbing color more stable. Co2O3 content greater than 0.4 mol% can reduce the chemical stability of the glass and increase its tendency to crystallize.

[0080] NiO is a colorant for light absorbing glass. The molar percentage (mol.%) of NiO is 0.1-1.0. 2+ It has good absorption effect in the visible light region. A NiO content greater than 1.0 mol% will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0081] MnO is a colorant for light absorbing glass. In this application, MnO plays a major role as a light absorber. MnO has a higher melting point than MnO2. 2+ It has stable light absorption ability between 400-700nm and can form stable coloring in glass. The molar percentage (mol.%) of MnO is 1.0-5.0. If the MnO content is greater than 5.0mol.%, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0082] V2O5 is a colorant in light-absorbing glass. The molar percentage (mol%) of V2O5 is 0.1-1.0. V2O5 solidifies the manganese ion coloring, making the light-absorbing material more stable. A V2O5 content greater than 1.0 mol% can reduce the chemical stability of the glass and increase its tendency to crystallize.

[0083] CeO2 is a rare earth oxide that mainly regulates the crystallization properties of glass and acts as a glass clarifier. The molar percentage (mol.%) of CeO2 is 0-0.2. When the CeO2 content is greater than 0.2 mol.%, the crystallization tendency of the glass will increase.

[0084] CuO is a colorant for light absorbing glass and can be used with Ni 2+ 、Co 3+ 、Mn 2+ The combination of the above can form a stable coloring in the glass. The composite absorption effect can ensure the absorption of stray light in the wavelength range of 400nm-700nm, obtain better light absorption effect, and make the light absorption curve have no obvious transmission peak in the visible light region. The molar percentage (mol.%) of CuO is 0-0.05, but when the CuO content is greater than 0.05mol.%, the crystallization tendency of the glass will increase.

[0085] The light-absorbing glass used in this application for ultra-narrow twist zone fiber optic image inverters can effectively improve the absorption of stray light between optical fibers, reducing crosstalk between fibers, thereby improving the contrast and clarity of the fiber optic image inverter. The use of light-absorbing sheathing technology can effectively improve the imaging uniformity of the fiber optic image inverter.

[0086] The light absorbing material glass of the present application can be applied to an ultra-narrow twisted-wire region optical fiber image inverter, and the ultra-narrow twisted-wire region optical fiber image inverter can be applied to a low-light-level image intensifier.

[0087] Specifically, the present application also provides an application of an ultra-narrow twisted fiber image inverter prepared by the preparation method in a low-light-level image intensifier. The ultra-narrow twisted fiber image inverter of the present application can be applied to helmet-mounted night vision devices.

[0088] Compared with the prior art, the ultra-narrow twisted fiber image inverter prepared in this application has the following advantages:

[0089] (1) The overall height of the ultra-narrow twisted fiber image invertor can be no more than 15 mm and the weight can be less than 20 g;

[0090] (2) The crosstalk of the ultra-narrow twisted fiber image inverter is less than 1.0% at a distance of 0.1 mm from the blade;

[0091] (3) The unit fiber diameter of the ultra-narrow twisted fiber image inverter is not greater than 4.0 μm, the center resolution of the ultra-narrow twisted fiber image inverter is greater than 140 lp / mm, and the edge resolution is greater than 110 lp / mm;

[0092] (4) The transmittance of the ultra-narrow twisted fiber image inverter is greater than 70% in the wavelength range of 400-700 nm;

[0093] (5) The ultra-narrow twisted fiber image inverter has excellent fixed pattern noise performance, and no obvious multifilament boundary is observed under a 10x microscope.

[0094] The ultra-narrow twisted wire area optical fiber image inverter of the present application has the advantages of good light transmittance uniformity, high resolution, high contrast and clear imaging. The ultra-narrow twisted wire area optical fiber image inverter of the present application is used in the low-light-level image intensifier, which can effectively reduce the volume and weight of the low-light-level image tube and improve the imaging clarity of the helmet night vision device. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] FIG1 is a schematic structural diagram of a leather glass tube provided in an embodiment of the present application with a surrounding wire tube on the outer layer;

[0096] FIG2 is a schematic diagram of a primary multifilament structure of an ultra-narrow twisted fiber image inverter provided in an embodiment of the present application;

[0097] FIG3 is a viscosity fitting curve of the core glass and the surrounding tube filament glass provided in an embodiment of the present application;

[0098] FIG4 is a transmittance curve of the light absorbing glass provided in an embodiment of the present application;

[0099] FIG5 is a schematic diagram of the structure of an ultra-narrow high-temperature zone torsion forming heating furnace provided in an embodiment of the present application;

[0100] FIG6 is a schematic diagram of an application of an ultra-narrow twisted fiber image invertor in a low-light-level image intensifier according to an embodiment of the present application;

[0101] FIG7 is a schematic diagram showing an application of an ultra-narrow twisted fiber image inverter provided in an embodiment of the present application, which is applied to a low-light-level image intensifier and then to a helmet-mounted night vision device.

[0102] In the figure: 1 is the cortex glass tube, 2 is the surrounding tube filament, 3 is the filling glass filament, 4 is the casing absorption filament, 5 is the core glass filament, and 6 is the cortex glass after the surrounding filament; 601 is the low-light image intensifier, 602 is the ultra-narrow twisted fiber image invertor, 603 is the image under low illumination, and 604 is the enhanced image; 701 is the helmet night vision device, 702 is the helmet, and 703 is the wearer; 801 is the ultra-narrow high-temperature zone twisting forming furnace, 802 is the heating element of the ultra-narrow high-temperature zone heating furnace, and 803 is the fiber image invertor blank; DETAILED DESCRIPTION

[0103] To make the purpose, technical solutions and advantages of this application clearer, the following further describes the implementation of this application in detail. The following further describes this application in detail with reference to the accompanying drawings and specific implementations, but does not limit this application.

[0104] Referring to FIG1 , the surrounding tube wire 2 is evenly wrapped around the outer side of the skin glass tube 1, and the core glass wire 5 is inserted into the skin glass tube 1. The matched rod-tube combination is drawn to form a monofilament.

[0105] Referring to FIG2 , the composition of the monofilament is that a core glass filament 5 is arranged in a surrounding skin glass 6, and after arranging the 6 monofilaments on each side into a primary composite rod with a hexagonal cross section, the monofilament arranged in the center of the hexagonal primary composite rod is replaced with a sleeve absorption filament 4, and then the triangular filling glass filament 3 is filled and inserted into the triangular pores of the primary composite rod, and the primary composite rod completed by the above combination is drawn into a primary multifilament as shown in FIG2 .

[0106] 3, the high temperature viscosity fitting curve of the surrounding tube filament 2 glass and the high temperature viscosity fitting curve of the core glass filament 5 in FIG3 are at the torsional viscosity point 10 7.6 The temperature at dPa.s is the same, so that the edge resolution of the prepared ultra-narrow twisted fiber image inverter can reach an effect greater than 110lp / mm.

[0107] Referring to FIG4 , which is a transmittance curve of the light absorbing material, it can be seen that the material has strong and uniform light absorption capability and spectral absorption effect within the wavelength range of 510-660 nm, with a spectral transmittance of ≤3.0%, so that the contrast of the prepared ultra-narrow twisted fiber image inverter can reach ≤1.0%.

[0108] Refer to Figure 5, which is a schematic diagram of the structure of the ultra-narrow high-temperature zone torsion forming heating furnace. The ultra-narrow high-temperature zone torsion forming furnace 801 is equipped with an ultra-narrow high-temperature zone heating furnace heating element 802. After the optical fiber inverter blank 803 is heated by the ultra-narrow high-temperature zone heating furnace heating element 802 in the ultra-narrow high-temperature zone torsion forming furnace 801, it is twisted and formed at an angle of 180° to prepare an ultra-narrow twisted wire zone optical fiber inverter.

[0109] Referring to FIG6 , which shows the application of an ultra-narrow twisted-wire region optical fiber image inverter in a low-light-level image intensifier, the ultra-narrow twisted-wire region optical fiber image inverter 602 prepared in the present application is applied in a low-light-level image intensifier 601. The low-light-level image intensifier 601 can convert an image 603 under low illumination into an enhanced image 604.

[0110] Referring to FIG7 , the ultra-narrow twisted-wire optical fiber image inverter 602 is used in a helmet-mounted night vision device. The ultra-narrow twisted-wire optical fiber image inverter 602 prepared in the present application is used in a low-light-level image intensifier 601 and is finally prepared into a helmet-mounted night vision device 701, which is installed in a helmet 702 and worn by a wearer 703.

[0111] In this document, all "mol. %" are based on the total molar amount of the final glass composition. The parameters, measurement methods, and instruments for the high refractive index filler glass used in the optical fiber imaging element of this application are as follows:

[0112] (1) The refractive index nD is the refractive index of the glass at λ = 589.3 nm, measured using a refractive index meter;

[0113] (2) Average linear thermal expansion coefficient α30 / 300[×10 -7 / ℃] is measured using a horizontal dilatometer and the method specified in GB / T 16920-2015;

[0114] (3) The strain point temperature of the glass is measured using the bending beam method specified in GB / T 28196-2011;

[0115] (4) The transmittance of glass is measured using a transmittance tester.

[0116] The glass chemical compositions (mol. %) of the examples are listed in detail in Tables 1, 2 and 3.

[0117] Table 1 Chemical composition (mol.%) and properties of the surrounding tube wire glass embodiment

[0118] Table 2 Chemical composition (mol.%) and properties of glass wool filled examples

[0119] Table 3 Chemical composition (mol.%) and properties of light absorbing glass examples

[0120] Example 1

[0121] A method for preparing an ultra-narrow twisted fiber image inverter comprises the following steps:

[0122] (1) Drawing of a tube wire: Referring to the glass composition of Example 1 in Table 1, a round glass rod with a low refractive index and a high strain point temperature was prepared, and the round glass rod was drawn into a Φ1.8 mm tube wire;

[0123] (2) Drawing of filling glass filaments: Referring to the glass composition of Example 1 in Table 2, a triangular glass rod with high refractive index and high transmittance was prepared, and the triangular glass rod was drawn into a triangular filling glass filament, wherein the height of the triangular filling glass filament was 0.63 mm;

[0124] (3) Drawing of sheathed absorbent wire: Referring to the glass composition of Example 1 in Table 3, a light absorbing material glass with good light absorbing performance was prepared into a light absorbing material glass rod, and then the light absorbing material glass rod was matched with a leather glass tube, and then drawn into a Φ2.8 mm sheathed absorbent wire;

[0125] (4) Single-filament drawing: The surrounding tube wire is evenly wrapped around the outer side of the leather glass tube, and then a high-refractive-index core glass rod is matched with the surrounding leather glass tube and single-filament drawing is performed to obtain a drawn single-filament, wherein the diameter of the single-filament is Φ2.8 mm;

[0126] (5) Drawing of a primary multifilament: Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross section, wherein each side of the primary composite rod has 6 monofilaments, and the total number of monofilaments in the arranged primary composite rod is 91; and replacing the monofilament arranged in the center of the hexagonal primary composite rod with the sleeve absorption yarn, and the diameter of the replaced monofilament is the same as that of the replaced sleeve absorption yarn; and filling the triangular pores of the primary composite rod with the triangular glass yarn; drawing the primary composite rod completed with the above combination into a primary multifilament, wherein the hexagonal opposite side size of the primary multifilament is 1.27 mm;

[0127] (6) Secondary multifilament drawing: The drawn primary multifilament is arranged into a secondary composite rod with a regular hexagonal cross section, wherein each side of the secondary composite rod has 12 strands. The secondary composite rod is then drawn into secondary multifilaments, wherein the hexagonal opposite side dimension of the secondary multifilaments is 0.91 mm. The secondary multifilaments are then cut to a fixed length and arranged into screen panel segments.

[0128] (7) Hot melt pressing: placing the screen plate segment into a hot melt pressing mold, and then placing the hot melt pressing mold into a hot melt pressing furnace, and hot melt pressing is performed according to the designed compression ratio before and after hot melt pressing of the plate segment. After hot melt pressing, the fiber optic image invertor blank plate segment is obtained;

[0129] (8) Twisting molding: The fiber optic image inverter blank plate segment is cut, rounded, and ground to prepare a fiber optic image inverter blank. The fiber optic image inverter blank is twisted at an angle of 180° in an ultra-narrow high-temperature zone twisting molding furnace. The width of the ultra-narrow high-temperature zone heating furnace body is 3 mm, and the distance between the heating furnace body and the surface of the fiber optic image inverter blank is 1.0 mm. The twisting molding time of the ultra-narrow twisted wire zone fiber optic image inverter blank at an angle of 180° is 5 minutes, thus preparing a high-resolution, high-contrast ultra-narrow twisted wire zone fiber optic image inverter with a unit fiber diameter of 3.96 μm.

[0130] The ultra-narrow twisted fiber image inverter prepared is 15mm high and weighs 19.4g. The crosstalk is 0.94% at a distance of 0.1mm from the blade; the center resolution is 143lp / mm and the edge resolution is 114lp / mm; it has excellent light transmission performance, with a transmittance of 72% in the wavelength range of 400-700nm; it has excellent fixed pattern noise performance, and there is no obvious multifilament boundary when observed under a 10x microscope.

[0131] Example 2

[0132] A method for preparing an ultra-narrow twisted fiber image inverter comprises the following steps:

[0133] (1) Drawing of a tube wire: Referring to the glass composition of Example 2 in Table 1, a round glass rod with a low refractive index and a high strain point temperature was prepared, and the round glass rod was drawn into a Φ1.6 mm tube wire;

[0134] (2) Drawing of filling glass filaments: Referring to the glass composition of Example 2 in Table 2, a high-refractive-index, high-transmittance equilateral triangular glass rod was prepared, and the equilateral triangular glass rod was drawn into a triangular filling glass filament, wherein the height of the triangular filling glass filament was 0.95 mm;

[0135] (3) Drawing of sheathed absorbent wire: Referring to the glass composition of Example 2 in Table 3, a light absorbing material glass with good light absorbing performance was prepared into a light absorbing material glass rod, and then the light absorbing material glass rod was matched with a leather glass tube, and then drawn into a Φ4.2 mm sheathed absorbent wire;

[0136] (4) Single filament drawing: The surrounding tube wire is evenly wrapped around the outer side of the leather glass tube, and then a high-refractive-index core glass rod is matched with the surrounding leather glass tube and single filament drawing is performed to obtain a drawn single filament, wherein the diameter of the single filament is Φ4.2 mm;

[0137] (5) Drawing of a primary multifilament: Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross section, wherein each side of the primary composite rod has 5 monofilaments, and the total number of monofilaments in the arranged primary composite rod is 61; and replacing the monofilament arranged in the center of the hexagonal primary composite rod with the sleeve absorption yarn, and the diameter of the replaced monofilament is the same as that of the replaced sleeve absorption yarn; and filling the triangular glass yarn into the triangular pores of the primary composite rod; and drawing the primary composite rod completed by the above combination into a primary multifilament, wherein the hexagonal opposite side size of the primary multifilament is 1.10 mm;

[0138] (6) Secondary multifilament drawing: The drawn primary multifilament is arranged into a secondary composite rod with a regular hexagonal cross section, wherein each side of the secondary composite rod has 14 strands. The secondary composite rod is then drawn into secondary multifilaments, wherein the hexagonal opposite side dimension of the secondary multifilaments is 0.88 mm. The secondary multifilaments are then cut to a fixed length and arranged into screen panel segments.

[0139] (7) Hot melt pressing: placing the screen plate segment into a hot melt pressing mold, and then placing the hot melt pressing mold into a hot melt pressing furnace, and hot melt pressing is performed according to the designed compression ratio before and after hot melt pressing of the plate segment. After hot melt pressing, the fiber optic image invertor blank plate segment is obtained;

[0140] (8) Twisting forming: The fiber optic image inverter blank plate segment is cut, rounded and ground to prepare a fiber optic image inverter blank. The fiber optic image inverter blank is twisted at an angle of 180° in an ultra-narrow high-temperature zone twisting forming furnace. The width of the heating element of the heating furnace body in the ultra-narrow high-temperature zone is 3.5 mm, and the distance between the heating element of the heating furnace body and the surface of the fiber optic image inverter blank is 1.2 mm. The twisting forming time of the ultra-narrow twisted wire zone fiber optic image inverter at an angle of 180° is 3 minutes, thus preparing an ultra-narrow twisted wire zone fiber optic image inverter with high resolution and high contrast and a unit fiber diameter of 3.94 μm.

[0141] The ultra-narrow twisted fiber image inverter prepared has a height of 14.9mm, a weight of 19.3g, and a crosstalk of 0.96% at a distance of 0.1mm from the blade; a center resolution of 143lp / mm, and an edge resolution of 128lp / mm; it has excellent light transmission performance, with a transmittance of 71% in the wavelength range of 400-700nm; it has excellent fixed pattern noise performance, and no obvious multifilament boundaries are observed under a 10x microscope.

[0142] Example 3

[0143] A method for preparing an ultra-narrow twisted fiber image inverter comprises the following steps:

[0144] (1) Drawing of a confined tube: Referring to the glass composition of Example 3 in Table 1, a round glass rod with a low refractive index and a high strain point temperature was prepared, and the round glass rod was drawn into a confined tube with a diameter of 2.0 mm;

[0145] (2) Filler filament drawing: Referring to the glass composition of Example 3 in Table 2, prepare a high-refractive-index, high-transmittance equilateral triangular glass rod, and draw the equilateral triangular glass rod into a triangular filler glass filament, wherein the height of the triangular filler glass filament is 0.5 mm;

[0146] (3) Drawing of sheathed absorbent wire: Referring to the glass composition of Example 3 in Table 3, a light absorbing material glass with good light absorbing performance was prepared into a light absorbing material glass rod, and then the light absorbing material glass rod was matched with a leather glass tube, and then drawn into a Φ2.4 mm sheathed absorbent wire;

[0147] (4) Single-filament drawing: The surrounding tube wire is evenly wrapped around the outer side of the leather glass tube, and then a high-refractive-index core glass rod is matched with the surrounding leather glass tube and single-filament drawing is performed to obtain a drawn single-filament, wherein the diameter of the single-filament is Φ2.4 mm;

[0148] (5) Drawing of a primary multifilament: Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross section, wherein each side of the primary composite rod has 7 monofilaments, and the total number of monofilaments in the arranged primary composite rod is 127; and replacing the monofilament in the center of the hexagonal primary composite rod with the sleeve absorption yarn, and the diameter of the replaced monofilament is the same as that of the replaced sleeve absorption yarn; and filling the triangular glass yarn into the triangular pores of the primary composite rod; and drawing the primary composite rod completed by the above combination into a primary multifilament, wherein the hexagonal opposite side size of the primary multifilament is 1.30 mm;

[0149] (6) Secondary multifilament drawing: The drawn primary multifilament is arranged into a secondary composite rod with a regular hexagonal cross section, wherein each side of the secondary composite rod has 11 fibers, and the secondary composite rod is drawn into a secondary multifilament, wherein the hexagonal opposite side dimension of the secondary multifilament is 0.96 mm, and the secondary multifilament is cut to a fixed length and arranged into screen plate segments;

[0150] (7) Hot melt pressing: placing the screen plate segment into a hot melt pressing mold, and then placing the hot melt pressing mold into a hot melt pressing furnace, and hot melt pressing is performed according to the designed compression ratio before and after hot melt pressing of the plate segment. After hot melt pressing, the fiber optic image invertor blank plate segment is obtained;

[0151] (8) Twisting forming: The fiber optic image inverter blank plate segment is processed by rolling, cutting and grinding to prepare a fiber optic image inverter blank. The fiber optic image inverter blank is twisted at an angle of 180° in an ultra-narrow high-temperature zone twisting forming furnace. The width of the heating element of the ultra-narrow high-temperature zone heating furnace is 4.0 mm, and the distance between the heating element of the heating furnace and the surface of the fiber optic image inverter blank is 1.5 mm. The 180° twisting forming time of the ultra-narrow twisted wire zone fiber optic image inverter is 6 minutes, thus preparing a high-resolution, high-contrast ultra-narrow twisted wire zone fiber optic image inverter with a unit fiber diameter of 3.92 μm.

[0152] The ultra-narrow twisted fiber image inverter prepared has a height of 15.0 mm, a weight of 19.4 g, and a crosstalk of 0.92% at a distance of 0.1 mm from the blade. The center resolution is 143 lp / mm and the edge resolution is 128 lp / mm. It has excellent light transmission performance, with a transmittance of 74% in the wavelength range of 400-700 nm. It has excellent fixed pattern noise performance, and no obvious multifilament boundaries are observed under a 10x microscope.

[0153] Example 4

[0154] The actual glass composition refers to the composition of Example 4 in Tables 1, 2 and 3, and the ultra-narrow twisted fiber image inverter is prepared using the same method as Example 1.

[0155] The ultra-narrow twisted fiber image inverter prepared has a height of 15.0 mm, a weight of 19.3 g, and a crosstalk of 0.96% at a distance of 0.1 mm from the blade. The center resolution is 143 lp / mm and the edge resolution is 114 lp / mm. It has excellent light transmission performance, with a transmittance of 73% in the wavelength range of 400-700 nm. It has excellent fixed pattern noise performance, and no obvious multifilament boundaries are observed under a 10x microscope.

[0156] Example 5

[0157] The actual glass composition refers to the composition of Example 5 in Tables 1, 2 and 3, and the ultra-narrow twisted fiber image inverter is prepared using the same method as Example 1.

[0158] The ultra-narrow twisted fiber image inverter prepared has a height of 15.0 mm, a weight of 19.3 g, and a crosstalk of 0.93% at a distance of 0.1 mm from the blade. It has a center resolution of 143 lp / mm and an edge resolution of 114 lp / mm. It has excellent light transmission performance, with a transmittance of 72% in the wavelength range of 400-700 nm. It has excellent fixed pattern noise performance, and no obvious multifilament boundaries are observed under a 10x microscope.

[0159] The embodiment described above is only one of the more optional specific implementation methods of the present application. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing an ultra-narrow twisted fiber image invertor, characterized in that: The following steps are involved: (1) Drawing of confined tube wire: Drawing a round glass rod with low refractive index and high strain point temperature into a confined tube wire of Φ1.6-2.0 mm; (2) Filled glass filament drawing: drawing a glass rod with high refractive index and high transmittance into filled glass filament; (3) Drawing of sheathed absorbent wire: preparing a light absorbing glass with good light absorbing performance into a light absorbing glass rod, then matching the light absorbing glass rod with a leather glass tube, and then drawing it into a sheathed absorbent wire; (4) Single-filament drawing: The surrounding tube wire is uniformly wrapped around the outer side of the sheath glass tube, and then the high-refractive-index core glass rod and the sheath glass tube after the wire are matched to draw the single-filament to obtain a drawn single-filament, wherein the wire diameter of the single-filament is the same as the wire diameter of the sheath absorption wire; (5) Drawing of primary multifilaments: Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross section, wherein each side of the primary composite rod has N monofilaments, and replacing the central monofilament arranged in the hexagonal primary composite rod with the sleeve absorption yarn, and inserting the filling glass yarn into the pores of the primary composite rod; drawing the primary composite rod assembled as above into primary multifilaments; (6) Secondary multifilament drawing: the drawn primary multifilaments are arranged into secondary composite rods with a regular hexagonal cross section, the secondary composite rods are drawn into secondary multifilaments, and the secondary multifilaments are cut to a fixed length and arranged into screen plate segments; (7) Hot melt pressing: placing the screen plate segment into a hot melt pressing mold, and then placing the hot melt pressing mold into a hot melt pressing furnace, and hot melt pressing is performed according to the designed compression ratio of the plate segment before and after hot melt pressing. After hot melt pressing, a fiber optic image invertor blank plate segment is obtained; (8) Twisting forming: the fiber image inverter blank plate segment is cut, rounded and ground to prepare a fiber image inverter blank, and the fiber image inverter blank is twisted at an angle of 180° in an ultra-narrow high-temperature zone twisting forming furnace to prepare an ultra-narrow twisted fiber image inverter; The width of the heating furnace body in the ultra-narrow high temperature zone is 3-4 mm, the distance between the heating furnace body and the surface of the optical fiber image inverter blank is 1.0-2.5 mm, and the twisting molding time of the optical fiber image inverter blank at a twisting angle of 180° is 2-9 minutes.

2. The preparation method according to claim 1, characterized in that: The filling glass fibers are triangular filling glass fibers; the height of the filling glass fibers is 0.50 to 0.95 mm; the diameter of the monofilament is Φ2.4 mm to Φ4.20 mm; Among them, the total number of monofilaments in the primary composite rod is (3N(N-1)+1), 8≥N≥3; The hexagonal opposite side size of the primary multifilament is 1.10 mm to 1.30 mm; The hexagonal opposite side size of the secondary multifilament is 0.86-1.06 mm.

3. An ultra-narrow twisted fiber image invertor prepared by the preparation method according to claim 1 or 2, characterized in that: The overall height of the ultra-narrow twisted wire area optical fiber image inverter is not more than 15mm, and the weight is less than 20g; the crosstalk of the ultra-narrow twisted wire area optical fiber image inverter is less than 1.0% at 0.1mm away from the knife edge; the unit fiber diameter of the ultra-narrow twisted wire area optical fiber image inverter is not more than 4.0 microns; the center resolution of the ultra-narrow twisted wire area optical fiber image inverter is greater than 140lp / mm, and the edge resolution is greater than 110lp / mm; the transmittance of the ultra-narrow twisted wire area optical fiber image inverter in the wavelength range of 400-700nm is greater than 70%; the ultra-narrow twisted wire area optical fiber image inverter has no obvious multifilament boundary when observed under a 10x microscope.

4. An application of the ultra-narrow twisted fiber image invertor according to claim 3 in a low-light level image intensifier.

5. The use according to claim 4, characterized in that: The low-light image intensifier is applied to helmet night vision devices.

6. A composition for confined tube wire, characterized in that: It is composed of the following components in mole percentage:

7. The composition according to claim 6, characterized in that It is composed of the following components in mole percentage:

8. The composition according to claim 6 or 7, characterized in that The refractive index of the glass of the surrounding tube wire is 1.48 to 1.51; the average linear thermal expansion coefficient in the range of 30 to 300°C is (80±5)×10 -7 / ℃, the strain point temperature of the glass of the surrounding tube wire is 580-620℃, the expansion softening temperature of the glass of the surrounding tube wire is 680-710℃, and the glass of the surrounding tube wire is 10 7.6 dPa.s viscosity at a temperature of 780-810°C, the glass material of the surrounding tube filament and the glass material of the core glass rod are 10 7.6 dPa.s at the same temperature when the torsional viscosity point is reached, the glass of the surrounding tube filament is kept at 850-900°C for 6 hours without crystallization or phase separation.

9. A composition for filling glass fibers, characterized in that: It is composed of the following components in mole percentage:

10. The composition according to claim 9, characterized in that It is composed of the following components in mole percentage:

11. The composition according to claim 9 or 10, characterized in that The refractive index of the glass filled with glass filaments is 1.80 to 1.82; the average linear thermal expansion coefficient in the range of 30 to 300°C is (90±5)×10 -7 / ℃, the strain point temperature of the glass of the triangular glass filament is 610-630℃, the transmittance of the glass filled with the glass filament is greater than 95% in the spectrum of 400-700nm, and there is no crystallization or phase separation when it is kept at 850-900℃ for 6 hours.

12. A composition for light absorbing glass, characterized in that: It is composed of the following components in mole percentage:

13. The composition according to claim 12, characterized in that It is composed of the following components in mole percentage:

14. The composition according to claim 12 or 13, characterized in that The light absorbing material glass has strong and uniform light absorption ability and spectral absorption effect in the wavelength range of 510-660nm at a thickness of 0.5±0.01mm, and the spectral transmittance is ≤3.0%; the thermal expansion coefficient of the light absorbing material glass is (85±5)×10 -7 / ℃; keep warm at 850-900℃ for 6 hours without crystallization or phase separation.

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