A high-transmittance optical fiber image transmission element and its preparation method and application

Abstract

The present invention discloses a high-transmittance optical fiber imaging element and its preparation method and application. The preparation method comprises the following steps: single-filament drawing: a high-refractive-index core glass rod and a low-refractive-index covering glass tube are matched to form a single-filament; triangular filling glass filament drawing: a high-refractive-index, high-transmittance triangular glass rod is drawn into triangular filling glass filaments; the drawn single-filaments are arranged as required into a primary composite rod, and the triangular filling glass filaments are evenly inserted into the gaps of the primary composite rod, and then drawn into a primary multifilament, which includes single-filaments and triangular filling glass filaments; the primary multifilaments are further arranged as required into a secondary composite rod, and the secondary composite rod is drawn into a secondary multifilament, and the secondary multifilaments are arranged into plate segments, and the plate segments are hot-melt-pressed to form an optical fiber blank, thereby obtaining a high-transmittance optical fiber imaging element. The optical fiber imaging element prepared by the present invention has the advantage of high transmittance.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber image transmission element manufacturing, and in particular to a high-transmittance optical fiber image transmission element and a preparation method and application thereof. Background Art

[0002] Fiber optic imaging components, including optical fiber panels, fiber image inverters, fiber tapers, and fiber image bundles, are high-performance optoelectronic imaging devices. They utilize a unique formulation of coating, core, and absorber materials, and are produced using a vacuum-controlled, rod-and-tube drawing process. This results in excellent airtightness, minimal distortion, and minimal speckle. They feature a simple structure, compact size, light weight, large numerical aperture, high light transmission efficiency, minimal interstage coupling loss, high coupling efficiency, high resolution, clear, accurate images, and optically zero thickness, which improves edge image quality. Fiber optic imaging components are high-resolution image transmission devices formed by heat-melting tens of millions of parallel optical fibers. They are key materials for image intensifiers and high-definition displays and are widely used in various cathode ray tubes, camera tubes, CCD coupling, low-light-level night vision, medical device displays, high-definition television imaging, and other instruments and equipment requiring image transmission in the military, criminal investigation, aerospace, and medical fields. They represent cutting-edge, high-tech products in the optoelectronics industry today.

[0003] The image transmission mechanism of fiber-optic imaging elements utilizes the principle of total internal reflection (TRIR) in optical fibers. The optical fibers that comprise these elements are manufactured through hot melt pressing, combining a low-refractive-index sheath glass tube, a high-refractive-index core glass rod, and light-absorbing glass filaments through a vacuum drawing process. Because the optical fibers are tightly fused together from the sheath glass, adjacent optical fibers are close together, leading to crosstalk between adjacent fibers. Alternatively, uneven thickness of the sheath glass tube caused by uneven temperature or drawing forces during the preparation process can cause input light to penetrate the sheath during total internal reflection, resulting in light leakage. Alternatively, defects or contaminants at the interface between the core and sheath fibers can disrupt the conditions for total internal reflection, causing light to scatter. This scattered light then enters adjacent fibers, causing crosstalk. The presence of stray light is a significant factor directly impacting the imaging quality of fiber-optic imaging elements, including contrast and clarity. Therefore, whether the low-light-level night vision device can capture sufficiently clear details is closely related to the transmittance of the fiber optic imaging element. Transmittance is an important performance indicator of fiber optic imaging products. With the continuous development of fiber optic imaging technology, the requirements for various product performances are getting higher and higher, and the fiber optic imaging element is the key material to ensure the imaging quality of the low-light-level night vision device. However, in the preparation process of the fiber optic imaging element product, the material matching and the mutual diffusion of components in the process will directly affect the transmittance of the fiber optic imaging element product. It is difficult to prepare high-transmittance fiber optic imaging element products. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-transmittance optical fiber imaging element and a preparation method thereof in view of the defects of the prior art.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing a high-transmittance optical fiber image transmission element comprises the following steps:

[0007] (1) Monofilament drawing: a core glass rod with a high refractive index and a skin glass tube with a low refractive index are matched to draw a monofilament; the diameter of the monofilament is Φ2.4 mm to Φ4.20 mm;

[0008] (2) Drawing of triangular filling glass fibers: Drawing a triangular glass rod with high refractive index and high transmittance into a triangular filling glass fiber; the cross section of the triangular filling glass fiber is triangular, and the height of the triangular filling glass fiber is 0.50 to 0.95 mm;

[0009] (3) Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross-section as required, with 6 monofilaments on each side and a total of 91 monofilaments in the arranged primary composite rod, and uniformly inserting the triangular filling glass fibers into the gaps of the primary composite rod, and then drawing the primary multifilaments, which include the monofilaments and the triangular filling glass fibers; the hexagonal opposite side dimensions of the primary multifilaments are 1.10 mm to 1.30 mm.

[0010] (4) The primary multifilaments are arranged into a secondary composite rod with a regular hexagonal cross section as required, the number of fibers on each side of the secondary composite rod is 12 to 17, the secondary composite rod is drawn into a secondary multifilament, the secondary multifilaments are arranged into plate segments, the hexagonal opposite side dimensions of the secondary multifilaments are 0.86-1.30 mm, the plate segments are formed into optical fiber blanks by hot melt pressing, and the optical fiber blanks are then finely processed to obtain high-transmittance optical fiber imaging elements.

[0011] The triangular filling glass fibers are composed of the following components in molar percentage:

[0012]

[0013]

[0014] Preferably, the triangular filling glass fibers are composed of the following components in molar percentage:

[0015]

[0016] Preferably, the triangular filling glass fibers are composed of the following components in molar percentage:

[0017]

[0018]

[0019] The refractive index of the triangular filling glass filament is 1.80-1.82; the average linear thermal expansion coefficient in the range of 30-300°C is (90±5)×10 -7 / ℃, the strain point temperature of the glass fiber is 620-640℃, the transmittance of the glass fiber in the spectrum of 400-700nm is greater than 95%, and there is no crystallization or phase separation when the glass fiber is kept at 850-900℃ for 6 hours.

[0020] The present invention also provides a high-transmittance optical fiber image transmission element, which is prepared according to the preparation method.

[0021] The present invention discloses a high-transmittance optical fiber imaging element, wherein the unit fiber diameter of the high-transmittance optical fiber imaging element is no greater than 4.0 microns, and the collimated light transmittance of the high-transmittance optical fiber imaging element within the wavelength range of 400-700nm is greater than 70%; the high-transmittance optical fiber imaging element has excellent fixed pattern noise performance, and no obvious multifilament boundaries are observed under a 10x microscope.

[0022] The present invention further provides an application of the high-transmittance optical fiber image transmission element in a low-light-level image intensifier.

[0023] In the triangular glass-filled composition of the present invention, 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. A SiO2 content exceeding 25.0 mol% increases the glass's high-temperature viscosity, resulting in excessively high melting temperatures and a reduced thermal expansion coefficient.

[0024] Al2O3 is an intermediate oxide of glass. 3+ Glass has two coordination states: located in tetrahedra or octahedra. When there is sufficient oxygen in the glass, aluminum oxide tetrahedra [AlO4] form, forming a continuous network with silicon oxide tetrahedra. When oxygen is insufficient, aluminum oxide octahedra [AlO6] form, which are external to the network and located within the cavities of the silicon oxide network. Therefore, within a certain content range, it can become the main component of the glass network, just like SiO2. The molar percentage of Al2O3 is 0-0.5 mol%, preferably 0.1-0.5 mol%. When the Al2O3 content exceeds 0.5 mol%, the melting temperature of the glass is significantly increased, and the high-temperature viscosity of the glass is significantly increased.

[0025] B2O3 is 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.

[0026] 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.

[0027] 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.%, the chemical resistance of the glass will be reduced and the thermal expansion coefficient of the glass will be increased.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

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

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

[0035] 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.

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

[0037] 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.

[0038] The triangular filling glass fibers of the present invention are inserted into triangular pores. The cross-section of the triangular filling glass fibers is triangular. When the triangular structure is used as the filling glass fibers in an optical fiber imaging element, the filling coefficient of the triangular structure is higher than that of the circular structure for pores of the same area. The triangular structure is more stable, and can prevent the internal fiber structure of the optical fiber imaging element from sliding or deflecting, thereby maintaining the stable total reflection structure of the optical fiber. Combined with the effects of the high refractive index and high transmittance triangular filling glass fibers, the useful light flux incident on the optical fiber is significantly increased, thereby improving the transmittance and transmittance uniformity of the optical fiber imaging element.

[0039] Compared with the prior art, the high-transmittance optical fiber imaging element provided by the present invention has the following beneficial effects:

[0040] The high-transmittance optical fiber imaging element prepared using the preparation method of the present invention has a crosstalk of less than 1% at a distance of 0.1 mm from the blade, a resolution greater than 140 lp / mm, excellent fixed pattern noise performance indicators, no obvious multifilament boundaries when observed under a 10x microscope, and a collimated light transmittance of greater than 70% in the wavelength range of 400-700 nm. The high-transmittance optical fiber imaging element can be used in low-light-level image intensifiers. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the internal structure of the optical fiber constituting the optical fiber imaging element provided by an embodiment of the present invention.

[0042] Figure 2 This is the collimated light transmittance curve of the high-transmittance optical fiber imaging element provided in Example 1 of the present invention at 400-700nm.

[0043] Among them, 1 is the triangular filling glass fiber, 2 is the core glass, and 3 is the skin glass. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, but this does not limit the present invention.

[0045] See also Figure 1 The skin glass tube and the core glass rod are matched and drawn into a monofilament. The monofilament includes an outer skin glass 3 and an inner core glass 2. Multiple monofilaments are tightly arranged into a hexagonal body with a regular hexagonal cross section, and triangular filling glass fibers 1 are provided between adjacent monofilaments.

[0046] See also Figure 2 , is the collimated light transmittance curve of the optical fiber imaging element made of triangular-filled glass fibers in the range of 400-700nm, tested according to the collimated light transmittance test method in GB / T 26597-2011. It can be seen from the curve that the collimated light transmittance is 74%-80% in the range of 400-700nm.

[0047] Herein, all "mol. %" are based on the total molar amount of the final glass composition. The glass chemical composition (mol. %) of the examples is detailed in Table 1.

[0048] The parameters, methods, and instruments used to measure the triangular glass-filled glass used in the high-transmittance optical fiber imaging element of the present invention are as follows:

[0049] (1) Refractive index n D is the refractive index of the glass at λ = 589.3 nm, measured using a refractive index meter;

[0050] (2) Average linear thermal expansion coefficient α at 30-300℃ 30 / 300 [×10 -7 / ℃] was measured using a horizontal dilatometer and the method specified in GB / T 16920-2015.

[0051] Table 1 Chemical composition (mol.%) and properties of glass yarn examples

[0052]

[0053]

[0054] Example 1

[0055] A method for preparing a high-transmittance optical fiber image transmission element comprises the following steps:

[0056] (1) Monofilament drawing: a high-refractive-index core glass rod and a low-refractive-index skin glass tube are matched to form a monofilament; the monofilament has a diameter of Φ2.8 mm;

[0057] (2) Drawing of filling glass yarn: Select raw materials according to the glass composition of Example 1 in Table 1, and strictly control the oxides of variable valence elements such as Fe2O3 in the glass raw materials. The Fe2O3 content of the finished glass is less than 150 ppm, and the ingredients are made to meet the glass chemical composition of Table 1. Then, prepare triangular glass rods with high refractive index and high transmittance. Then, draw the prepared triangular glass rods with high refractive index and high transmittance into triangular filling glass yarns; the height of the triangular filling glass yarns is controlled to be 0.63 mm.

[0058] (3) Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross-section as required, with 6 monofilaments on each side, and a total of 91 monofilaments in the arranged primary composite rod, and uniformly inserting triangular filling glass fibers into the gaps of the primary composite rod, and then drawing them into primary multifilaments, which include monofilaments drawn from a rod-tube combination and triangular filling glass fibers drawn from a glass rod with a high refractive index and high transmittance; the hexagonal opposite side size of the primary multifilaments is 1.27 mm;

[0059] (4) The primary multifilaments are arranged into a secondary composite rod with a regular hexagonal cross section as required, the number of fibers on each side of the secondary composite rod is 12, the secondary composite rod is drawn into a secondary multifilament, the secondary multifilaments are arranged into plate segments, the hexagonal opposite side size of the secondary multifilaments is 0.91 mm, the plate segments are formed into optical fiber blanks by hot melt pressing, and the optical fiber blanks are then finely processed to obtain high-transmittance optical fiber imaging elements.

[0060] The unit fiber diameter of the prepared high-transmittance optical fiber imaging element is 3.96μm, and the crosstalk is 0.94% at 0.1mm from the blade; the central resolution is 143lp / mm; it has excellent light transmission performance, with an average collimated light transmittance of 75.8% 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.

[0061] Example 2

[0062] A method for preparing a high-transmittance optical fiber image transmission element comprises the following steps:

[0063] (1) Monofilament drawing: a high-refractive-index core glass rod and a low-refractive-index skin glass tube are matched to form a monofilament; the monofilament has a diameter of Φ2.4 mm;

[0064] (2) Drawing of triangular filling glass filaments: Select raw materials according to the glass composition of Example 2 in Table 1, and strictly control the oxides of variable valence elements such as Fe2O3 in the glass raw materials. The Fe2O3 content of the finished glass is less than 150 ppm, and the ingredients are made to meet the glass chemical composition of Table 1. Then, prepare triangular glass rods with high refractive index and high transmittance, and then draw the prepared triangular glass rods with high refractive index and high transmittance into triangular filling glass filaments; the height of the filling glass filaments is controlled to be 0.50 mm;

[0065] (3) Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross-section as required, with 6 monofilaments on each side and a total of 91 monofilaments in the arranged primary composite rod, and evenly inserting triangular filling glass fibers into the gaps of the primary composite rod, and then drawing the rod into a primary multifilament, which includes the monofilaments and the triangular filling glass fibers; the hexagonal opposite side size of the primary multifilament is 1.30 mm.

[0066] (4) The primary multifilaments are arranged into a secondary composite rod with a regular hexagonal cross section as required, and the number of fibers on each side of the secondary composite rod is 17. The secondary composite rod is drawn into a secondary multifilament, and the secondary multifilaments are arranged into plate segments, and the hexagonal opposite side size of the secondary multifilaments is 1.30 mm. The plate segments are formed into optical fiber blanks by hot melt pressing, and the optical fiber blanks are then finely processed to obtain high-transmittance optical fiber imaging elements.

[0067] The unit fiber diameter of the prepared optical fiber imaging element is 3.96μm, and the crosstalk is 0.96% at 0.1mm from the blade; the central resolution is 143lp / mm; it has excellent light transmittance, with an average collimated light transmittance of 75.2% 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.

[0068] Example 3

[0069] (1) Single-filament drawing: A high-refractive-index core glass rod and a low-refractive-index skin glass tube are matched to form a single-filament; the diameter of the single-filament is Φ4.20 mm;

[0070] (2) Drawing of triangular filling glass filaments: Select raw materials according to the glass composition of Example 3 in Table 1, and strictly control the oxides of variable valence elements such as Fe2O3 in the glass raw materials. The Fe2O3 content of the finished glass is less than 150 ppm, and the ingredients are made to meet the glass chemical composition of Table 1. Then, prepare triangular glass rods with high refractive index and high transmittance, and then draw the prepared triangular glass rods with high refractive index and high transmittance into triangular filling glass filaments; the height of the triangular filling glass filaments is controlled to be 0.95 mm;

[0071] (3) Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross-section as required, with 6 monofilaments on each side and a total of 91 monofilaments in the arranged primary composite rod, and evenly inserting the triangular filling glass fibers into the gaps of the primary composite rod, and then drawing them into a primary multifilament, which includes the monofilaments and the triangular filling glass fibers; the hexagonal opposite side size of the primary multifilament is 1.10 mm.

[0072] (4) The primary multifilaments are arranged into a secondary composite rod with a regular hexagonal cross section as required, the number of fibers on each side of the secondary composite rod is 12, the secondary composite rod is drawn into a secondary multifilament, the secondary multifilaments are arranged into plate segments, the hexagonal opposite side size of the secondary multifilaments is 0.86 mm, the plate segments are formed into optical fiber blanks by hot melt pressing, and the optical fiber blanks are then finely processed to obtain high-transmittance optical fiber imaging elements.

[0073] The unit fiber diameter of the prepared optical fiber imaging element is 3.92μm, and the crosstalk is 0.92% at 0.1mm from the blade; the central resolution is 143lp / mm; it has excellent light transmittance, with an average collimated light transmittance of 75.6% 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.

[0074] Example 4

[0075] The actual composition of the filling glass refers to the composition of Example 4 in Table 1, and the optical fiber imaging element is prepared using the same method as Example 1.

[0076] The unit fiber diameter of the prepared optical fiber imaging element is 3.96μm, and the crosstalk is 0.94% at 0.1mm from the blade; the central resolution is 143lp / mm; it has excellent light transmittance, with an average collimated light transmittance of 75.7% 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.

[0077] Example 5

[0078] The actual composition of the filling glass refers to the composition of Example 5 in Table 1, and the optical fiber imaging element is prepared using the same method as Example 1.

[0079] The unit fiber diameter of the prepared optical fiber imaging element is 3.96μm, and the crosstalk is 0.94% at 0.1mm from the blade; the central resolution is 143lp / mm; it has excellent light transmittance, with an average collimated light transmittance of 75.5% 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.

[0080] 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 in the scope of protection of the present invention.

Claims

1. A method for preparing a high-transmittance optical fiber imaging element, characterized in that: The following steps are involved: (1) Monofilament drawing: a core glass rod with a high refractive index and a skin glass tube with a low refractive index are matched to draw a monofilament; the diameter of the monofilament is Φ2.4 mm to Φ4.20 mm; (2) Drawing of triangular filling glass fibers: Drawing a triangular glass rod with high refractive index and high transmittance into a triangular filling glass fiber; the cross section of the triangular filling glass fiber is triangular, and the height of the triangular filling glass fiber is 0.50 to 0.95 mm; (3) Arranging the drawn monofilaments into a primary composite rod with a regular hexagonal cross section as required, with 6 monofilaments on each side and a total of 91 monofilaments in the arranged primary composite rod, and uniformly inserting the triangular filling glass filaments into the gaps of the primary composite rod, and then drawing the primary composite rod into a primary multifilament, the primary multifilament comprising the monofilaments and the triangular filling glass filaments; the hexagonal opposite side size of the primary multifilament is 1.10 mm to 1.30 mm; (4) Arranging the primary multifilaments into a secondary composite rod with a regular hexagonal cross section as required, wherein the number of fibers on each side of the secondary composite rod is 12 to 17, drawing the secondary composite rod into secondary multifilaments, arranging the secondary multifilaments into plate segments, wherein the hexagonal opposite side dimensions of the secondary multifilaments are 0.86 to 1.30 mm, hot-melt-pressing the plate segments into optical fiber blanks, and then fine-processing the optical fiber blanks to obtain high-transmittance optical fiber imaging elements; The triangular filling glass fibers are composed of the following components in molar percentage:

2. The preparation method according to claim 1, characterized in that The triangular filling glass fibers are composed of the following components in molar percentage:

3. The preparation method according to claim 1, characterized in that The triangular filling glass fibers are composed of the following components in molar percentage:

4. The preparation method according to any one of claims 1 to 3, characterized in that The refractive index of the triangular filling glass filament is 1.80-1.82; the average linear thermal expansion coefficient in the range of 30-300°C is (90±5)×10 -7 / ℃, the strain point temperature of the glass fiber is 620-640℃, the transmittance of the glass fiber in the spectrum of 400-700nm is greater than 95%, and there is no crystallization or phase separation when the glass fiber is kept at 850-900℃ for 6 hours.

5. A high-transmittance optical fiber image transmission element, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 4.

6. The high-transmittance optical fiber imaging element according to claim 5, characterized in that: The unit fiber diameter of the high-transmittance optical fiber imaging element is no more than 4.0 microns, and the collimated light transmittance of the high-transmittance optical fiber imaging element in the wavelength range of 400-700nm is greater than 70%; the high-transmittance optical fiber imaging element has no obvious multifilament boundary when observed under a 10x microscope.

7. Use of the high-transmittance optical fiber imaging element according to claim 5 or 6 in a low-light-level image intensifier.

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