Optical fiber image transmission array and preparation method and application thereof

Abstract

The invention relates to an optical fiber image transmission array and a preparation method and application thereof. The method comprises the following steps: screening a core material glass rod and a skin material glass tube based on machine learning; drawing the core material glass rod and the skin material glass tube into monofilaments; drawing the black absorption glass rod into light absorption glass fibers; performing hexagonal densest arrangement on the monofilaments, inserting light absorption glass fibers into gaps of the monofilaments to obtain a primary composite rod, and drawing the primary composite rod into primary multifilaments; arranging the primary multifilament in a hexagonal densest manner to form a secondary composite rod, and drawing the secondary composite rod into a secondary multifilament; performing hexagonal densest arrangement on the secondary multifilaments to obtain an arrangement plate section with a regular hexagonal structure; carrying out hot melt press molding and optical fiber plate blank processing on the arrangement plate sections to obtain an optical fiber plate blank; and post-processing the optical fiber plate blank. Through the formula design of glass components, the difference of ultraviolet transmission of the fiber core and the fiber skin is realized, so that the optical fiber image transmission array with the end face having the micron-sized well structure is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical elements, and in particular relates to an optical fiber image transmission array and a preparation method and application thereof. Background Art

[0002] Fiber-optic imaging arrays (FIIAs) are optical fiber arrays that transmit images in proportion, invert them by 180°, or magnify or reduce them. They primarily consist of optical fiber panels, optical fiber image invertors, and optical fiber tapers. They feature zero optical thickness, high resolution, and high light-collecting capabilities. They are used in imaging devices such as image intensifiers, image converters, and photoelectric coupling devices. Their applications have expanded to low-light-level night vision, particle detection, high-energy radiation detection, medical devices, and numerous scientific research fields. They are important dual-use components for military and civilian use. As a core component in devices such as image intensifiers, image converters, intensified charge-coupled devices (ICCDs), or complementary metal-oxide semiconductors (CMOSs), their performance determines the imaging quality of these devices.

[0003] With the advancement of low-light-level night vision technology and fiber-optic imaging array manufacturing technology, especially the emergence of 4G+ and NVT-7 in recent years, which represent the highest level of low-light-level night vision technology, more stringent requirements have been placed on the thermal, optical, and chemical properties of fiber-optic imaging arrays, such as high contrast, high resolution, high modulation index, wide spectrum, and high transmittance. These properties directly determine the device's detection range, detail resolution, and field of view. Currently, research on fiber-optic imaging arrays, both domestically and internationally, focuses on improving resolution through structural means to achieve efficient coupling and enhance device clarity and resolution. In fact, when coupling fiber-optic imaging arrays with CCDs, end-face optical phenomena and internal losses are also important factors that lead to a decrease in coupling efficiency, restricting the application and expansion of fiber-optic imaging arrays and limiting the development of digital low-light-level imaging technology.

[0004] At present, the input end face of the traditional fiber optic imaging array is directly obtained through a polishing process, and both the input and output ends of the fiber optic imaging array are flat: at the input end, due to the nearly spherical shape of the phosphor, the photons excited by electrons hitting the phosphor are diverged, resulting in a portion of the light being unable to be input into the fiber optic imaging array, causing light loss at the input end and reducing the transmittance of the fiber optic imaging array; at the output end, after being transmitted in the fiber optic imaging array, the light is in a divergent state at the end face, which will lead to a reduction in the resolution of the fiber optic imaging array.

[0005] Since the image transmission unit of the fiber optic imaging array - the optical fiber is a micron-level structural unit, it is difficult to achieve a micro-well structure that corresponds one-to-one to the image transmission unit using ordinary processing methods. Summary of the Invention

[0006] In view of this, the main purpose of the present invention is to provide a fiber optic imaging array and its preparation method and application. The technical problem to be solved is to achieve the difference in ultraviolet transmittance between the fiber core and the fiber skin through the design of glass component formula, thereby obtaining a fiber optic imaging array with a micron-level well structure on the end face, so that the phosphor can be filled in the micro-well at the input end, and then the light is confined in the micro-well without being scattered, thereby reducing the light loss at the input end and increasing the light flux entering the fiber optic imaging array for transmission, thereby improving the resolution and transmittance of the fiber optic imaging array and reducing optical crosstalk.

[0007] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. The present invention proposes a method for preparing a fiber optic image transmission array, comprising the following steps:

[0008] S11 selects core glass rods and skin glass tubes based on machine learning; matches the obtained core glass rods and skin glass tubes and draws them into monofilaments; and draws black absorbing glass rods into light-absorbing glass filaments;

[0009] S12: the monofilaments obtained in step S11 are arranged in a hexagonal closest packing pattern, the obtained light-absorbing glass fibers are inserted into the gaps in the hexagonal closest packing pattern, and the primary composite rods are obtained by bundling, and the obtained primary composite rods are drawn into primary multifilaments;

[0010] S13: the primary multifilament obtained in step S12 is formed into a secondary composite rod by hexagonal close-packed arrangement, and then drawn into a secondary multifilament;

[0011] S14: the secondary multifilaments obtained in step S13 are arranged in a hexagonal closest-packed manner, and bundled to obtain a regular hexagonal plate segment;

[0012] S15: hot-melt-pressing the panel segments obtained in step S14 and processing the optical fiber panel blanks to obtain optical fiber panel blanks;

[0013] S16: The optical fiber plate blank obtained in step S15 is post-processed to obtain the optical fiber image transmission array.

[0014] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0015] Preferably, in the aforementioned method for preparing the optical fiber imaging array, in step S11, the drawing temperature of the single filament is 750-770°C, and the rod-dropping speed is 25-30 mm / min; the drawing temperature of the light-absorbing glass filament is 800-820°C, and the rod-dropping speed is 22-27 mm / min; the drawing temperature of the interstitial filament is 700-720°C, and the rod-dropping speed is 28-33 mm / min.

[0016] Preferably, in the aforementioned method for preparing the optical fiber imaging array, in step S11, the diameter of the single filament is 4.3±0.1 mm; the diameter of the light-absorbing glass filament is 0.3±0.05 mm; and the diameter of the interstitial filament is 0.2±0.05 mm.

[0017] Preferably, in the aforementioned method for preparing an optical fiber imaging array, in step S12, the drawing temperature is 760-780°C, the rod drawing speed is 20-23 mm / min, and the opposite side dimension of the primary multifilament is 2.3±0.1 mm.

[0018] Preferably, in the aforementioned method for preparing an optical fiber imaging array, in step S13, the drawing temperature is 750-770°C, the rod drawing speed is 18-20 mm / min, and the opposite side dimension of the secondary multifilament is 1.8±0.1 mm.

[0019] Preferably, in the aforementioned method for preparing the optical fiber imaging array, in step S15, the temperature of the hot melt pressing is 620-630° C., the time is 80-150 min, the pressure is 10-15 MPa, and the pressing scale is 3-6 mm.

[0020] Preferably, in the aforementioned method for preparing the optical fiber imaging array, in step S16, the post-processing comprises the following steps:

[0021] The fiber optic panel is obtained by rounding the fiber optic plate blank and then cutting, grinding and polishing it.

[0022] Preferably, in the aforementioned method for preparing the optical fiber imaging array, in step S16, the post-processing comprises the following steps:

[0023] a1 twists the fiber optic plate blank to obtain a fiber optic image invertor blank;

[0024] b1 Grind and polish the end face of the fiber optic image inverter blank. Grind with a grinder for 1-2 hours and polish with a polisher for 1.5-3 hours. After passing the inspection, the fiber optic image inverter is obtained.

[0025] Preferably, in the aforementioned method for preparing the optical fiber imaging array, in step S16, the post-processing comprises the following steps:

[0026] a2 stretches the optical fiber plate blank and then cuts it into two to obtain an optical fiber taper blank;

[0027] b2 Grind and polish the end face of the fiber optic taper blank. Grind with a grinder for 1-2 hours and polish with a polisher for 1.5-3 hours. After passing the performance test, the fiber optic taper is obtained.

[0028] The objectives of the present invention and the technical problems solved therein can be further achieved by adopting the following technical measures: The present invention proposes a fiber optic imaging array comprising an output end, an input end, and a fiber portion disposed between the output and input ends; the fiber optic imaging array is manufactured by the above-mentioned method.

[0029] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures. The present invention proposes a method for preparing a microlens-shaped optical fiber image transmission array, comprising the following steps:

[0030] S21: uniformly coating the photoresist on the input end of the optical fiber imaging array by a static spin coating method, and then pre-baking the photoresist to remove the solvent in the photoresist to form a uniform film, enhance the adhesion to the substrate, and solidify the photoresist film layer to avoid problems during subsequent exposure and development, thereby obtaining a photoresist film layer with high uniformity, low surface defects, micron-level thickness, and stable consistency;

[0031] S22: exposing the optical fiber imaging array obtained in step S21, with one end surface coated with a cured adhesive layer, so that the exposed and unexposed areas correspond to the imaging units of the optical fiber imaging array one by one; then performing post-baking to ensure that the adhesive layer in the exposed area is fully cured; and then performing development to reveal the adhesive layer pattern.

[0032] In step S23 , the optical fiber imaging array developed in step S22 is immersed in an etchant for wet etching, so that the end face presents a micro-well structure, thereby obtaining the micro-lens-shaped optical fiber imaging array.

[0033] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0034] Preferably, in the aforementioned method for preparing the microlens-shaped optical fiber imaging array, in step S21, the photoresist is a UV negative photoresist for 365nm exposure.

[0035] The objectives of the present invention and the technical problems solved therein can be further achieved by the following technical measures. The present invention proposes a microlens-shaped optical fiber imaging array having a plurality of microwell structures on its end face, wherein the opening diameter of the microwell structures ranges from a maximum of 3-6 μm to a minimum of 2-4 μm, and the well depth ranges from a maximum of 3-5.5 μm to a minimum of 2-3.5 μm. The microlens-shaped optical fiber imaging array is manufactured by the above-described method.

[0036] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures: The present invention proposes an optical system, which includes the above-mentioned micro-lens-shaped optical fiber image transmission array.

[0037] By means of the above technical solution, the present invention provides a fiber optic image transmission array and its preparation method and application, which have at least the following advantages:

[0038] The present invention achieves the difference in ultraviolet transmittance between the fiber core and the fiber sheath through the design of glass component formula, thereby obtaining an optical fiber imaging array with a micron-level well structure on the end face, so that phosphor can be filled in the micro-well at the input end. The light excited by electrons striking the nearly spherical phosphor is confined in the micro-well, so that the light will not be transmitted in a stray form, thereby reducing light loss at the input end and increasing the light flux entering the optical fiber imaging array for transmission, thereby improving the resolution and transmittance of the optical fiber imaging array and reducing optical crosstalk. When coupled with a CCD or other devices, the coupling efficiency, coupling resolution and coupling transmittance are improved.

[0039] The fiber optic imaging array fabrication method of the present invention achieves a micro-well-shaped end face structure, unlike the planar structure of conventional components. By designing the glass composition formula, the difference in ultraviolet transmittance between the core and the sheath is achieved, resulting in a fiber optic imaging array with a micron-scale well structure on the end face. This allows phosphor to be filled in the micro-well at the input end. Light excited by electrons striking the nearly spherical phosphor is trapped in the micro-well, preventing it from straying out. This reduces light loss at the input end and increases the light flux entering the fiber optic imaging array for transmission, thereby improving the resolution and transmittance of the fiber optic imaging array and reducing optical crosstalk. When coupled with a CCD or other device, this improves coupling efficiency, coupling resolution, and coupling transmittance.

[0040] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flow chart of a process for preparing an optical fiber imaging array according to some embodiments of the present invention;

[0042] Figure 2 A flow chart of the preparation process of a microlens-shaped optical fiber imaging array according to some embodiments of the present invention;

[0043] Figure 3 Schematic diagram of the UV lithography process for preparing micro-well structures according to some embodiments of the present invention;

[0044] Figure 4 Schematic diagram of the static spin coating process of some embodiments of the present invention;

[0045] Figure 5 Schematic diagram of the microscopic process of immersion development according to some embodiments of the present invention;

[0046] Among them, 1 is optical fiber imaging array, 2 is negative photoresist, 3 is photoresist that undergoes cross-linking reaction, and 4 is photoresist that does not undergo cross-linking reaction. DETAILED DESCRIPTION

[0047] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with preferred embodiments, describes in detail a fiber optic image sensor array, its preparation method, and its specific implementation, structure, features, and effectiveness. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0048] The following materials or reagents, unless otherwise specified, were commercially available.

[0049] like Figure 1 As shown, some embodiments of the present invention provide a method for preparing a fiber optic imaging array, comprising the following steps:

[0050] S11 selects core glass rods and skin glass tubes based on machine learning; matches the obtained core glass rods and skin glass tubes and draws them into monofilaments; and draws black absorbing glass rods into light-absorbing glass filaments;

[0051] S12: the monofilaments obtained in step S11 are arranged in a hexagonal closest packing pattern, the obtained light-absorbing glass fibers are inserted into the gaps in the hexagonal closest packing pattern, and the primary composite rods are obtained by bundling, and the obtained primary composite rods are drawn into primary multifilaments;

[0052] S13: the primary multifilament obtained in step S12 is formed into a secondary composite rod by hexagonal close-packed arrangement, and then drawn into a secondary multifilament;

[0053] S14: the secondary multifilaments obtained in step S13 are arranged in a hexagonal closest-packed manner, and bundled to obtain a regular hexagonal plate segment;

[0054] S15: hot-melt-pressing the panel segments obtained in step S14 and processing the optical fiber panel blanks to obtain optical fiber panel blanks;

[0055] S16: The optical fiber plate blank obtained in step S15 is post-processed to obtain the optical fiber image transmission array.

[0056] In some optional embodiments, in step S11, the conditions for machine learning to screen the core and core glass composition formulas are: the transmittance ratio of the i-line (wavelength of 365nm) (ultraviolet light transmittance T2 of the core glass / ultraviolet light transmittance T1 of the fiber sheath glass) is less than 0.3, the refractive index ratio (ultraviolet light refractive index n2 of the core glass / ultraviolet light refractive index n1 of the fiber sheath glass) is greater than 1.2, and its linear expansion coefficient, glass transition temperature, refractive index and density and other key properties meet the fiber forming process requirements. The fiber forming requirements specifically refer to: the linear expansion coefficient must be within (60±5)×10-6 / ℃, the difference between the fiber core and fiber sheath materials must be less than 5×10 -6 The fiber's core and sheath glass compositions are designed to be 1000°C / °F (1000°C / °C) and 1000°C / °C (1000°C / °C) respectively, avoiding delamination or microcracks caused by temperature cycling. The glass transition temperature must be within the range of 500±5°C (a value higher than the operating temperature) to prevent softening and deformation and maintain structural stability in high-temperature environments. The core refractive index must be 1.45±0.2, and the sheath refractive index must be 1.43±0.2, with the difference between the two greater than 0.5%. The density must be within the range of 1.8±0.5, with a higher density enhancing the fiber's mechanical strength. Experiments were conducted to verify the core and sheath glass compositions predicted by three machine learning algorithms: random forest, k-nearest neighbor, and gradient boosting decision tree. The optimal formula was selected by comparing the experimental and predicted results.

[0057] In some optional embodiments, in step S11, the drawing temperature of the monofilament is 750-770°C, and the rod withdrawal speed is 25-30 mm / min; the drawing temperature of the light-absorbing glass filament is 800-820°C, and the rod withdrawal speed is 22-27 mm / min; and the drawing temperature of the interstitial filament is 700-720°C, and the rod withdrawal speed is 28-33 mm / min. The drawing temperature and rod withdrawal speed are set based on the thermal properties (e.g., thermal expansion coefficient, softening temperature) and mechanical properties (e.g., brittleness, hardness) of the glass, as well as the state of the drawn filament (e.g., filament diameter, ovality). If the temperature is too high (such as greater than 770℃ or greater than 820℃ or greater than -720℃) or the rod lowering speed is too fast (such as greater than 30mm / min or greater than 27mm / min or greater than 33mm / min), the wire diameter will be uneven and the wire ovality will be too large; if the temperature is too low (such as less than 750℃ or less than 800℃ or less than 700℃) or the rod lowering speed is too slow (such as less than 25mm / min or less than 22mm / min or less than 28mm / min), the wire diameter will be too thin, and in severe cases, the wire will be damaged or even broken.

[0058] In some optional embodiments, in step S11, the diameter of the monofilament is 4.3±0.1mm; the diameter of the light-absorbing glass filament is 0.3±0.05mm; and the diameter of the interstitial filament is 0.2±0.05mm. The above three wire diameter ranges are determined based on two aspects: feasibility and finished product performance (such as resolution, field of view cleanliness, etc.). If the wire diameter is too large, feasibility is strong but the finished product resolution is poor. If the wire diameter is too small, resolution is high but feasibility is poor and the finished product field of view cleanliness is difficult to guarantee. The wire diameter range is set based on the balance between these two factors.

[0059] In some optional embodiments, in step S12, the drawing temperature is 760-780°C, the rod drawing speed is 20-23 mm / min, and the opposite side dimension of the primary multifilament is 2.3±0.1 mm.

[0060] In some optional embodiments, in step S13, the drawing temperature is 750-770°C, the rod drawing speed is 18-20 mm / min, and the opposite side dimension of the secondary multifilament is 1.8±0.1 mm.

[0061] The temperature and rod-drawing speed for drawing multifilaments are set according to the glass properties of the composite rod and the state of the drawn multifilaments. If the temperature and rod-drawing speed are inappropriate, the composite rod will be over-softened or not softened enough, which will affect the size and ovality of the drawn multifilaments. The opposite side dimensions of the multifilaments affect the operability of its drawing and the wire diameter of the finished product: if the opposite side dimensions of the primary multifilaments are too large, such as greater than 2.4mm, the wire diameter of the secondary multifilaments will be too large, which will affect the resolution of the finished product. If the opposite side dimensions of the secondary multifilaments are too large, such as greater than 1.9mm, the wire diameter of the finished product will be too large, which will affect the resolution of the finished product. If the opposite side dimensions of the primary and secondary multifilaments are too small (such as less than 2.2mm or less than 1.7mm), the drawing operability will be poor and the cost will be too high. The opposite side dimensions of the primary and secondary multifilaments are set based on the drawing operability while ensuring the resolution of the finished product.

[0062] In some optional embodiments, in step S15, the temperature of the hot melt press molding is 620-630°C, the time is 80-150min, the pressure is 10-15MPa, and the pressure scale is 3-6mm. Determination of the parameters of hot melt press molding is a comprehensive process, which requires a systematic analysis in combination with material properties and process objectives. The pressure scale is an indicator of the degree of material melting. If it is less than 3mm, the material is not fully melted, and if it is greater than 6mm, the material is over-melted. The melting temperature range depends on the material properties of the plate segment (such as melting point and thermal stability, viscosity and fluidity, shrinkage and thermal expansion coefficient). If the temperature is too high, such as greater than 630°C, it may cause decomposition, and if it is too low, such as less than 620°C, it cannot be fully melted. The size of the pressure will affect the fluidity of the material and the filling of the mold. Insufficient pressure (such as less than 10MPa) will cause the plate segment to be loose or have bubbles, and too high pressure (such as greater than 15MPa) will damage the mold or cause the material to overflow. Therefore, the pressure is determined according to the viscosity and fluidity of the material and the design of the mold. The melting and pressing time must ensure that the material is fully melted. If the time is not enough (such as less than 80 minutes), the material will not be fully melted. If the time is too long (such as more than 150 minutes), it will lead to increased energy consumption or material degradation. In addition, the melting and pressing time is related to production efficiency. The time parameters need to be adjusted in combination with the thermal conductivity of the material and the heat capacity of the mold. In terms of process goals, the surface quality, mechanical properties and other requirements of the product will affect the selection of parameters. For high-precision products such as fiber optic imaging arrays, more precise temperature and pressure control, as well as longer process time, are required to ensure that the pressing scale is reached.

[0063] In some optional embodiments, in step S16, the post-processing includes the following steps:

[0064] The fiber optic plate blank is rounded and then cut, ground, and polished. After passing the inspection, the fiber optic panel is obtained. The cutting speed is 0.1-0.5mm / s. If the cutting speed is too fast (such as greater than 0.5mm / s), it is easy to cause edge collapse, and if the cutting speed is too slow (such as less than 0.1mm / s), the efficiency is low; the cutting angle should be perpendicular to the fiber axis, and the angle deviation must be less than 0.5°. If the deviation is too large (such as greater than 0.5°), the phase shift of the finished product will not meet the standard. Then, the damaged layer caused by cutting is removed by grinding. The abrasive used for grinding is diamond sand with a particle size of #2500. If the particle size is too large, the flatness is difficult to meet. If the particle size is too small, the cutting force is insufficient, and it takes time to remove the damaged layer; the grinding disc speed is 150-170rpm, ensuring efficiency while keeping the speed low to reduce heat accumulation; the grinding time is 1-2h, which is adjusted according to the hardness of the fiber material. The end face of the sample after grinding has a frosted texture, and the end face is polished using a polishing process. Polishing is performed using a highly elastic polishing pad and a cerium oxide polishing slurry with a particle size of 1μm. The polishing pressure is 40-50kPa. Excessive pressure can easily lead to edge collapse, while insufficient pressure will not achieve the desired polishing effect. The polishing speed is 80-100rpm, with a low speed ensuring uniformity. The polishing time is 1.5-3 hours. Insufficient polishing time (e.g., less than 1.5 hours) will make it difficult to achieve the desired polishing effect, while excessive polishing time (e.g., more than 3 hours) can easily lead to edge collapse. Performance testing criteria are: field of view cleanliness refers to spots <25μm, chicken wire <0.2mm; resolution >90lp / mm; distortion includes serpentine distortion ≤20μm, shear distortion ≤30μm, and phase shift ≤100μm; and dimensional accuracy is ±0.1mm.

[0065] In some optional embodiments, in step S16, the post-processing includes the following steps:

[0066] a1. Twist the fiber optic plate blank to obtain the fiber optic image invertor blank. The twisting operation parameters are: twist angle of 180°±1°, twisting temperature of 800±20℃; low speed twisting is used, 0.5° / s<rotation speed<1° / s. If the speed is too low (e.g., less than 0.5° / s), heat accumulation will cause severe fiber deformation, while high speed twisting (e.g., greater than 1° / s) will easily induce microcracks. The setting of these parameters is constrained by the mechanical properties (torsional strength) and optical properties of the fiber optic plate blank. If the twisting effect is not ideal, the imaging distortion of the finished product will not meet the standards.

[0067] b1. Grind and polish the end face of the fiber optic image invertor blank for 1-2 hours on a grinder and 1.5-3 hours on a polisher. Once qualified, the fiber optic image invertor is ready. Performance testing criteria include: field of view cleanliness (spotting <25μm, chicken wire <0.2mm); resolution >90lp / mm; distortion (including serpentine distortion ≤40μm, shear distortion ≤30μm, and phase shift ≤150μm); torsion angle 180°±1°; and dimensional accuracy ±0.1mm.

[0068] In some optional embodiments, in step S16, the post-processing includes the following steps:

[0069] a2. Stretch the fiber optic sheet blank rod and then cut it in two to obtain the fiber taper blank. The stretching operation parameters are as follows: Based on the transition temperature of the fiber optic sheet blank rod, set the stretching temperature to 120±5℃. High temperatures (such as greater than 125℃) will cause severe deformation of the optical fiber, while low temperatures (such as less than 115℃) will not reach the transition temperature of the fiber optic sheet blank rod, and the optical fiber will break during the stretching process. The stretching speed is 1-3mm / s. High speeds (such as greater than 3mm / s) can easily lead to sudden changes in the taper area, while low speeds (such as less than 1mm / s) can form a smooth transition.

[0070] b2 Grind and polish the end face of the fiber taper blank for 1-2 hours using a grinder and 1.5-3 hours using a polisher. The fiber taper is then tested and qualified. The performance test criteria are: field cleanliness: spot size <90μm, chicken wire ≤0.2mm; resolution >90lp / mm; distortion: snake distortion ≤1.5% of the effective area diameter, shear distortion ≤30μm, barrel / pincushion distortion ≤3% of the effective area diameter, phase shift ≤300μm; air tightness: air leakage rate <2.0×10 - 12 Pa·m 3 ·s -1 ; The external dimensions meet the accuracy of ±0.1mm.

[0071] Some embodiments of the present invention also provide a fiber optic image transmission array comprising an output end, an input end, and an optical fiber portion disposed between the output and input ends; the fiber optic image transmission array is manufactured using the above-described method. The fiber optic image transmission array primarily comprises an optical fiber panel, an optical fiber image invertor, and an optical fiber taper. The optical fiber panel is composed of tens of millions of micron-sized optical fibers arranged and fused together in a regular pattern. Each optical fiber is composed of a high-refractive-index core and a low-refractive-index sheath. Light is transmitted within the fiber according to the principle of total internal reflection, resulting in high resolution, large numerical aperture, and zero optical thickness, enabling high-fidelity proportional transmission of optical images. The optical fiber image invertor is constructed by synchronously rotating tens of millions of optical fibers 180° around their geometric optical axis on the basis of the optical fiber panel. Therefore, it inherits all the properties of the optical fiber panel and can invert the image 180°, achieving an inverted image. This solves the problems of conventional optical inverting systems, such as large size, high field curvature, and low resolution, and offers leading advantages in high resolution, high contrast, ultra-short torsion zone, and low distortion. The optical fiber cone is made by heating, softening and stretching the blank plate based on the optical fiber panel. It can achieve the special effect of image magnification or reduction. It is a key component for coupling the low-light image intensifier and CCD to realize the digital processing of low-light night vision images.

[0072] like Figure 2 As shown, some embodiments of the present invention further provide a method for preparing a microlens-shaped optical fiber image transmission array, comprising the following steps:

[0073] The S21 is based on a static spin coating method, where a 365nm exposure UV negative photoresist is evenly coated on the input end of the fiber optic imaging array. A pre-baking process is then performed to solidify the photoresist film, resulting in a highly uniform (film thickness error <5%), low surface defect (surface defect <20μm), micron-level (1-2μm) thickness, and stable consistency (standard deviation <5%) photoresist film. The static spin coating method consists of three steps: the first step is a rotation speed of 350-550r·min -1 , 3-7s; the second step, the speed is 2500-3300r·min -1 , 3-7s; the third step, the speed is 3500-4300r·min -1 , 12-18s. While spreading the glue evenly, avoid high-speed centrifugal force causing excessive glue to be thrown out, which may lead to a thin glue layer or glue edge accumulation. If the speed is too low (such as less than 350r·min -1 or less than 2500r·min -1 or less than 3500r·min -1 If the time is too short (such as less than 3s or less than 12s), the glue layer will be too thick, the edge glue will accumulate, and even the glue will not spread out. If the speed is too fast (such as greater than 550r·min -1or greater than 3300 r·min -1 or greater than 4300r·min -1 ) will result in an uneven adhesive layer, with the center area being too thin. In severe cases, lines will appear on the surface of the adhesive layer. Pre-baking can generally be done on a hot plate or in an oven. Based on the advantages of high temperature uniformity of the hot plate and its suitability for rapid removal of solvents, and the fact that the oven is not suitable for baking thick adhesives, a hot plate baking method is adopted. According to the viscosity, thickness and solvent volatilization rate of the UV negative photoresist for 365nm exposure, the baking temperature is set to 80-100°C and the baking time is set to 6-10min. If the pre-baking temperature is too low (such as less than 80°C) or the baking time is too short (under-baking, such as less than 6min), solvent residues will remain in the photoresist. These residual solvents will evaporate in the subsequent exposure process, resulting in unclear graphics. If the pre-baking temperature is too high (such as greater than 100°C) or the baking time is too long (over-baking, such as greater than 10min), the photosensitive agent will be destroyed during the pre-baking process, resulting in a decrease in the sensitivity of the photoresist. The static spin coating method is used to prepare a photoresist film layer with high uniformity, low surface defects, micron-level thickness and stable consistency on the end face of the optical fiber imaging array. The specific coating process is as follows: Figure 4 As shown in the figure, a proper amount of photoresist is first dropped onto the center of the end face of the optical fiber imaging array using a pipette. The device is then rotated at a low speed to spread the photoresist, and then rotated at a high speed to remove the excess photoresist. Therefore, in this process, process parameters such as the viscosity of the photoresist, the amount of glue dropped, the coating speed, and the coating time are very critical to the quality of the photoresist layer.

[0074] A pre-baking process is then performed using a hot plate bake method. The bake temperature (80-100°C) and bake time (6-10 minutes) are set to volatilize the organic solvent in the photoresist at high temperature, solidifying the photoresist film on the end face of the fiber optic imaging array. Generally speaking, most of the solvent has evaporated during the coating process, but a considerable amount of solvent still remains in the photoresist film. The pre-baking process further dries and solidifies the film, improving the adhesion between the photoresist and the input end of the fiber optic imaging array and reducing the occurrence of dark corrosion during the development process.

[0075] Based on the structural particularity and complexity of the microlens-shaped optical fiber imaging array, the present invention uses a UV negative photoresist. During the exposure process, the photosensitizer in the negative photoresist 2 absorbs UV light and triggers a cross-linking reaction, causing the double bonds between molecules to open and form a high molecular cross-linked structure that is insoluble in the developer, that is, the photoresist 3 that undergoes the cross-linking reaction. The unexposed portion that is soluble in the developer, that is, the photoresist 4 that does not undergo the cross-linking reaction, is removed during the development process, thereby realizing a micro-well structure in the photoresist layer. The structure in the photoresist layer is then replicated on the surface of the optical fiber imaging array 1 through an etching system, as shown in FIG. Figure 3 shown.

[0076] S22 exposes the optical fiber imaging array with a cured adhesive layer coated on one end face, and realizes a one-to-one correspondence between the exposed and unexposed areas and the imaging units of the optical fiber imaging array based on the difference in the glass composition of the fiber core and the fiber skin; then a post-baking process is used to promote the cross-linking reaction to ensure that the colloid in the exposed area is fully cured; then the development is performed to make the adhesive layer pattern appear, so as to obtain an ideal micro-well structure in the photoresist film layer, that is, arranged in a honeycomb pattern, with a single structure corresponding to each optical fiber one-to-one, and the micro-well presents a smooth arc-shaped three-dimensional structure from the core center of the optical fiber to the edge of the fiber skin, with surface defects less than 30μm. The exposure uses the URE-2000B UV lithography system, and the UV exposure dose (200-300mJ / cm 2 ), overexposure (such as greater than 300mJ / cm 2 ) will result in narrower line width, while insufficient exposure (such as less than 200mJ / cm 2) results in unclear images; an i-line (365nm) light source is used based on the micron-scale dimensions of the microwell structure. The core's molar composition is 4-8% lead, 2-5% multiple rare earth elements, and 2-7% titanium oxide, vanadium oxide, and iron oxide (higher than the molar ratio of these three oxides in the sheath (0.2-1%)). These elements and oxides enhance the core glass's UV absorption, creating a difference in UV absorption between the core and sheath. The core strongly absorbs UV light, while the sheath transmits it. During exposure, the core absorbs UV light, preventing crosslinking in this area, leaving it unexposed. However, UV light passes through the sheath, causing crosslinking in that area, exposing the sheath. Consequently, the exposed and unexposed areas correspond to the sheath and core of each optical fiber in the fiber imaging array, respectively. The post-baking time is set to 8-15 minutes based on the thickness of the negative photoresist layer, and the post-baking temperature is set to 100-140°C based on the glass transition temperature of the photoresist. Overbaking (such as more than 15 minutes, the time is too long or more than 140°C, the temperature is too high) will cause the colloid to become brittle, prone to cracking during development, and even worse, carbonization of the colloid. Underbaking (such as less than 8 minutes, the time is too short or less than 100°C, the temperature is too low) will result in low cross-linking degree and partial dissolution of the exposed area during development. Immersion developer solutions include propylene glycol monomethyl ether acetate, tetramethylammonium hydroxide, xylene, and mixtures of xylene and polar solvents (such as isopropyl alcohol or acetone). Based on the photoresist type, resist thickness, and developer properties, the preferred developer is a 3:1 volume ratio of xylene and isopropyl alcohol. Based on the resist layer thickness (1-2 μm) and resist properties, the immersion time should be 10-25 seconds, the development temperature should be 25±5°C, and a magnetic stirrer (100-200 rpm) should be used for development. Overdevelopment (i.e., immersion time longer than 25 seconds, development temperature higher than 30°C) can lead to colloid swelling and rough sidewalls, while immersion time shorter than 10 seconds and development temperature lower than 20°C can result in incomplete development. A magnetic stirrer speed lower than 100 rpm makes it difficult to ensure uniform developer contact with the resist surface, resulting in edge accumulation. However, a speed higher than 200 rpm can damage delicate structures and cause surface defects. The ideal micro-well structure of the prepared photoresist film layer is arranged in a honeycomb pattern, with a single structure corresponding one-to-one to the image transmission unit of the optical fiber image transmission array. The micro-well presents a smooth arc-shaped three-dimensional structure from the core center of the optical fiber to the edge of the fiber sheath.

[0077] During the preparation of the microlens-shaped optical fiber imaging array, in order to make the micro-well structure accurately correspond to the imaging unit in the optical fiber imaging array, the existing exposure technology is modified to be suitable for the preparation of this structure.

[0078] An optical fiber imaging array coated with a cured, highly uniform photoresist film on one end face is exposed. The other end face of the optical fiber imaging array is irradiated with ultraviolet light for exposure. Due to the difference in glass composition between the core and the sheath, the core absorbs ultraviolet light while the sheath transmits ultraviolet light. A micro-well structure corresponding to the imaging units of the optical fiber imaging array is prepared in the photoresist film. The ultraviolet exposure process of the present invention does not require a mask. A URE-2000B ultraviolet lithography system is used. An appropriate ultraviolet exposure dose (200-300mJ / cm2) is set according to the thickness of the photoresist film and the size of the optical fiber. 2 ), based on the difference in the glass composition of the fiber core and fiber skin, precise control of the exposure area is achieved, and the photoresist in the exposed part undergoes a cross-linking reaction to form a network structure that is insoluble in the developer.

[0079] Since the present invention uses a negative photoresist, a post-baking process is used to promote crosslinking of the photoresist in the exposed areas by thermally stimulating the diffusion of photoacids. The baking temperature (100-140°C) and baking time (8-15 minutes) are set to effectively promote the crosslinking reaction and ensure that the colloid in the exposed areas is fully cured.

[0080] Development is a key step in making the glue layer pattern appear, and it has a decisive influence on the subsequent etching morphology and dimensional accuracy. The present invention adopts an immersion development method, using tweezers to immerse the optical fiber imaging array to be developed in the developer. By changing the immersion time (10-25s), changing the development temperature (25±5℃), adding a magnetic stirrer, etc., the developer is made to fully react with the unexposed photoresist 4 that has not undergone a cross-linking reaction and then dissolve in the developer. The cross-linked photoresist 3 remains intact on the end face of the optical fiber imaging array 1 after development, thereby obtaining an ideal micro-well pattern in the photoresist film layer. The microscopic change process is as follows: Figure 5 shown.

[0081] S23 immerses the developed optical fiber imaging array in an etchant for a wet etching process. Due to the corrosiveness of the etchant, the undeveloped portion is protected by the photoresist and is not corroded, while the developed portion undergoes a chemical reaction without the protection of the adhesive layer, causing the end face to present a micro-well structure, thereby obtaining an optical fiber imaging array with a micro-well structure. The etchant may be a phosphoric acid mixture, a buffered hydrofluoric acid solution, potassium hydroxide, or the like. Based on a comprehensive consideration of the substrate material, the chemical resistance of the photoresist, and the etching target (selectivity, anisotropy, etc.), the preferred etchant is hydrofluoric acid (HF) buffered with ammonium fluoride (NH4F), i.e., a buffered hydrofluoric acid solution (BHF, with a volume ratio of HF:NH4F:H2O of 1:5:10 to 1:10:10). This is because ammonium fluoride decomposes to produce HF, thereby maintaining a stable HF concentration. Excessive etching, i.e., excessively high concentration (e.g., a volume ratio of HF:NH4F:H2O greater than 1:5:10), will result in pattern distortion, while insufficient concentration (e.g., a volume ratio of HF:NH4F:H2O less than 1:10:10) will make it difficult to achieve an etching effect. The water used to prepare the etchant is deionized water, the etching temperature is maintained in the range of 35±5℃, and the etching time is 8-13min; if the etching temperature is higher than 40℃ and the time is longer than 13min, excessive lateral etching and photoresist peeling will occur, and in severe cases, the substrate will be corroded. If the temperature is lower than 30℃ and the time is shorter than 8min, the etching effect cannot be achieved.

[0082] After obtaining the glue layer structure, based on the strong chemical corrosion resistance of the negative photoresist, the present invention uses a wet etching process to copy the glue layer structure to the input end face of the optical fiber imaging array. With the help of the chemical reaction between the etchant and the optical fiber imaging array, the part protected by the photoresist coating that undergoes the cross-linking reaction does not undergo a chemical reaction, while the part not protected by the glue layer coating and exposed to the etchant undergoes a chemical reaction with the etchant, and this part is dissolved to achieve the purpose of etching. By setting the etchant concentration, etching time, etching temperature, and stirring method, etc., the etching is carried out normally. Finally, the desired shape is etched according to the difference in the composition of the fiber core and fiber sheath glass, thereby successfully realizing a micro-well structure on the end face of the optical fiber imaging array.

[0083] The photoresist on the end faces of the etched fiber optic imaging array is then removed through wet debonding using a strongly oxidizing solution (a mixture of concentrated sulfuric acid and hydrogen peroxide). This dissolves the remaining photoresist on the end faces, achieving the desired debonding process and producing a microlens-shaped fiber optic imaging array.

[0084] The microlens-shaped optical fiber imaging array fabricated above was observed under a metallographic microscope to check whether the microwell structure on the optical fiber faceplate met the desired specifications. The criteria for evaluation were: the microwells were arranged in a regular honeycomb pattern, forming a smooth, curved, three-dimensional microwell structure from the center of the optical fiber core to the edge of the fiber sheath; the microwell dimensions were an opening diameter of 4±2μm and a depth of 4±2μm; and surface defects were less than 20μm.

[0085] The present invention uses glass materials with an ultraviolet light transmittance ratio (core glass ultraviolet light transmittance T2 / sheath glass ultraviolet light transmittance T1) less than 0.3 and a refractive index ratio (core glass n2 / sheath glass n1) greater than 1.2 as the raw materials for the optical fiber imaging array. The optimal core and core glass compositions selected by machine learning prediction and experimental verification are used as a formula to be melted into glass rod and tube materials; then, the optical fiber imaging array is produced through a series of tedious processes such as wire drawing and rod arrangement, hot melt pressing, optical fiber plate blank processing, precision annealing or 180° twisting or stretching, and external shaping. The prepared optical fiber imaging array is then used as a substrate, and through a complete set of complex processes such as glue coating, exposure, development, and etching, a micro-well structure is prepared on the end face of the optical fiber imaging array to obtain a micro-lens optical fiber imaging array.

[0086] Some embodiments of the present invention also provide a microlens-shaped optical fiber imaging array, whose end face has a plurality of microwell structures; after testing, the opening diameter of the microwell structure is 3-6 μm at most and 2-4 μm at least, and the well depth is 3-5.5 μm at most and 2-3.5 μm at least; the microlens-shaped optical fiber imaging array is arranged in a honeycomb pattern, and a single structure is a smooth arc-shaped microwell-shaped solid from the core center of the optical fiber to the edge of the fiber skin; the microlens-shaped optical fiber imaging array is manufactured by the above method.

[0087] Some embodiments of the present invention also provide an optical system, comprising the aforementioned microlens-shaped fiber optic imaging array. Conventional optical systems use a flat input end face for the fiber optic imaging array. At the input end, the photons excited by electrons striking the phosphors diverge due to their near-spherical shape, preventing some light from entering the fiber optic imaging array. This results in light loss at the input end and reduces the transmittance of the fiber optic imaging array. At the output end, the light is divergent at the end face after being transmitted through the fiber optic imaging array, reducing the resolution of the fiber optic imaging array and, in turn, the resolution of the entire optical system. The optical system provided by the present invention uses a microlens-shaped fiber optic imaging array to replace the fiber optic imaging array with a flat input end face. Phosphor can be filled in the microwell at the input end of the microlens-shaped fiber optic imaging array, confining light in the microwell and reducing light loss at the input end. This improves the resolution and transmittance of the fiber optic imaging array, reduces optical crosstalk, and improves coupling efficiency, coupling resolution, and coupling transmittance when coupled with a CCD or other device.

[0088] In the above-mentioned technical solution, the present invention achieves differential UV transmittance between the core and sheath through glass composition design, thereby producing a fiber optic imaging array with a micron-scale well structure on the end face. This allows phosphor to be filled in the micro-wells at the input end, confining light within the micro-wells without straying, thereby reducing light loss at the input end and increasing the light flux entering the fiber optic imaging array. This improves the resolution and transmittance of the fiber optic imaging array, reduces optical crosstalk, and achieves improved coupling efficiency, coupling resolution, and coupling transmittance when coupled with a CCD or other device. The present invention does not rely on a mask, but instead uses machine learning to design a unique glass composition formula: the glass composition formula of the fiber core contains lead, multiple rare earth elements, and a higher content of metal oxides such as titanium oxide, vanadium oxide, and iron oxide than the sheath. This gives the core strong UV absorption and the sheath strong UV transmittance, thereby achieving perfect matching of the exposed and unexposed areas with the sheath and core of each optical fiber in the fiber optic imaging array. This is the key technology of the present invention. In addition, during the molding process, the optical fiber imaging array undergoes high-temperature processes such as hot pressing, annealing, torsion, or stretching. The core and sheath components will penetrate each other from the interface at high temperature. Therefore, the ultraviolet transmittance from the core center of the optical fiber to the edge of the sheath tends to continuously decrease, so that the micro-well structure formed on the end face after ultraviolet light irradiation is a smooth arc-shaped micro-well three-dimensional structure from the core center of the optical fiber to the edge of the sheath.

[0089] The present invention will be further described below with reference to specific embodiments.

[0090] Example 1: Preparation of a Microlens-Shaped Optical Fiber Panel

[0091] 10. Preparation of optical fiber panels

[0092] The optical fiber panel produced in this step is composed of tens of millions of micron-sized optical fibers, arranged and fused in a regular pattern. Each optical fiber is composed of a high-refractive-index core and a low-refractive-index sheath. Each optical fiber acts as an image transmission unit, independently transmitting a pixel from the input end to the output end.

[0093] The specific steps include:

[0094] 101. The optimal core and core glass compositions selected based on machine learning are used as a formula and melted into glass rod and tube materials, which serve as the raw materials for the optical fiber, the image transmission unit of the optical fiber panel.

[0095] In this step, the molar ratio of the glass composition of the core selected based on the machine learning random forest algorithm is: 5% lead, multiple rare earth elements (Ce 4+ 、Eu 2+ 、Nd 3+) 3%, titanium oxide + vanadium oxide + iron oxide 5%, SiO2 67%, Al2O3 3%, CaO 5%, Na2O 10%, MgO 1%, Fe2O3 1%; the glass composition of the fiber sheath is as follows: titanium oxide + vanadium oxide + iron oxide 0.2%, SiO2 79.8%, Al2O3 3%, CaO 5%, Na2O 10%, MgO 1%, Fe2O3 1%. The lead and rare earth elements doped in the fiber core, as well as the higher content of titanium oxide, vanadium oxide, and iron oxide in the fiber sheath, give the fiber core strong UV absorption and the fiber sheath strong UV transmission.

[0096] 102. Molten glass rods and tubes are used as core rods and jacket tubes to draw monofilaments, and black rods are drawn into light-absorbing glass filaments. The monofilament drawing temperature is 760°C, the rod withdrawal speed is 28 mm / min, and the monofilament diameter is 4.3 ± 0.05 mm. The light-absorbing glass filament drawing temperature is 810°C, the rod withdrawal speed is 25 mm / min, and the light-absorbing glass filament diameter is 0.3 ± 0.02 mm. A fiber optic imaging array contains tens of millions of monofilaments and light-absorbing glass filaments. It is difficult to achieve uniform diameters for all tens of millions of filaments, so the diameters fluctuate within a range.

[0097] In this step, the core rods and the skin tubes are screened and their sizes are inspected. The black rods are made of Schott OG590 glass, which has excellent light absorption properties (absorption rate can reach 99% in the visible to near-infrared range, i.e., 400-1500nm).

[0098] 103. Arrange the monofilaments in a hexagonal close-packed pattern, insert light-absorbing glass filaments into the gaps between the hexagonal close-packed patterns, and bundle them to form a primary composite rod; draw the primary composite rod to form a primary multifilament; arrange the primary multifilament in a hexagonal close-packed pattern to form a secondary composite rod; draw the secondary composite rod to form a secondary multifilament; arrange the secondary multifilament in a hexagonal close-packed pattern and bundle them with copper wire to form a regular hexagonal plate segment. The primary multifilament is drawn at a temperature of 770°C, a rod withdrawal speed of 21 mm / min, and a width across the primary multifilament of 2.3 ± 0.02 mm; the secondary multifilament is drawn at a temperature of 760°C, a rod withdrawal speed of 19 mm / min, and a width across the secondary multifilament of 1.8 ± 0.02 mm.

[0099] 104. The panel segments are subjected to processes such as hot melt pressing and optical fiber panel blank processing to obtain optical fiber panel blanks.

[0100] In this step, the plate segment is placed under a vacuum of 1.33×10 -6The hot melt pressing process is carried out under the conditions of 625°C, 120 minutes, 12 MPa, and a 4.3 mm press scale to obtain a melt-pressed plate segment. The blank is then processed according to the product size requirements to obtain the optical fiber plate blank. The hot melt pressing process temperature is 625°C, time is 120 minutes, pressure is 12 MPa, and the press scale is 4.3 mm.

[0101] 105. The obtained optical fiber plate blank is subjected to annealing, shape processing, performance testing and other processes to obtain an optical fiber panel.

[0102] In this step, the fiber optic panel blank is kept at a high temperature (700°C) for 24 hours for precision annealing to obtain the optical fiber panel blank, with the heating and cooling rate being 2°C / min. The panel is then processed according to the drawings and subjected to performance testing to obtain an optical fiber panel that meets the specifications. The performance test items and results are as follows: the field of view cleanliness meets the maximum spot size of 25μm and the maximum chicken wire size of 0.2mm; the resolution is 106lp / mm; the serpentine distortion is 10μm, the shear distortion is 8μm, the phase shift is 60μm; the air leakage rate is 1.8×10 -12 Pa·m 3 ·s -1 The machining accuracy of the external dimensions meets ±0.1mm. The precision annealing process is carried out in a high-purity argon atmosphere (flow rate 8L / min). The temperature is raised to 700°C at a rate of 5°C / min (to avoid microcracks caused by thermal shock) and held for 10 hours. The temperature is then lowered to 400°C at a rate of 2°C / min and then cooled to room temperature in the furnace.

[0103] 11. Preparation of highly uniform photoresist film layer

[0104] Using a static spin coating method, a UV negative photoresist for 365nm exposure is evenly coated on the input end of the optical fiber faceplate. A pre-baking process is then performed to solidify the photoresist film layer, resulting in a highly uniform, low-surface-defect, micron-level thick, and consistent photoresist film layer. The specific steps include:

[0105] 111. Pre-treat the photoresist and substrate, i.e., the optical fiber panel, before applying the glue: let the supercooled photoresist stored in a refrigerator at 5°C stand until it returns to room temperature before opening the lid for use; ultrasonically treat the optical fiber panel (use an ultrasonic cleaner for 10 minutes), clean it, and then use an electric hot plate to bake it at 210°C for 2 minutes, and then store the treated optical fiber panel in a dry container.

[0106] Steps 111-115 must be performed in the following environment: the temperature is maintained at 23°C, the relative humidity is maintained at 50%, and the air cleanliness is a Class 100 purification state.

[0107] 112. After preparation, fix the optical fiber panel processed in step 111 on the vacuum stage of the coating machine with the help of a clamp, exposing only the input end face of the optical fiber panel.

[0108] To achieve a highly uniform and low-defect photoresist film in this step, the end face of the optical fiber panel to be coated must be clean and intact. Therefore, when moving the optical fiber panel, be sure to avoid touching the end face; use tools such as tweezers. The fixture and various tools used during the operation must be cleaned with alcohol or ultrasonically cleaned before use.

[0109] 113. Use a pipette to absorb the photoresist and then drop it on the middle area of the input end of the optical fiber panel. The whole process should be done gently to avoid introducing bubbles.

[0110] The present invention uses i-line (365nm) exposure UV negative photoresist, whose performance index meets the following requirements: sensitivity of 200mJ / cm 2 , the contrast is 3, the critical size for resolution is 0.8 μm, the viscosity is 30 cP, and the content of metal impurities (Na, K, Mn, Fe, Al) is 0.8×10 -8 wt%. In addition, the amount of photoresist dripped in this step is determined according to the viscosity of the photoresist and the size of the end face of the optical fiber panel to be coated. Taking a diameter of 18.3 mm as an example: the viscosity is 10 cP and the dripping amount is 4 mL.

[0111] 114. Start the photoresist machine to perform the spin coating process to obtain a photoresist film layer with a thickness of micron level.

[0112] In this step, the spin coating program set by the glue machine is: Step 1, speed 500r·min -1 , 5s; second step, speed 3000r·min -1 , 5s; Step 3, speed 4000r·min -1 , 15s.

[0113] The average thickness of the prepared photoresist film layer is 1.5 μm, the thickness error is 1.5%, the standard deviation is 2%, the consistency is stable, and the maximum surface defect is 17 μm.

[0114] 115. Place the optical fiber panel after spin coating with the uncoated end facing down on a hot plate for pre-baking process to evaporate the residual organic solvent in the photoresist and dry and solidify the glue layer.

[0115] In this step, the optical fiber panel after spin coating is placed on a hot plate with the uncoated end facing downward, and the process parameters are set as follows: baking temperature is 80° C. and baking time is 8 minutes.

[0116] After baking, it needs to be cooled to room temperature before proceeding with subsequent processes. The next exposure process can be carried out after the adhesive layer has completed the water reabsorption process to ensure the development speed and high contrast.

[0117] 12. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0118] An optical fiber panel coated with a cured adhesive layer on one end face is exposed. Based on the difference in the glass composition of the fiber core and the fiber sheath, the exposed and unexposed areas are matched one-to-one with the image transmission unit of the optical fiber panel, and a cross-linking reaction occurs in the exposed area. A post-baking process is then used to promote the cross-linking reaction in the exposed area to ensure that the colloid in the exposed area is fully cured. After that, development is performed to make the adhesive layer pattern appear, thereby obtaining an ideal micro-well structure in the photoresist film layer.

[0119] The specific steps include:

[0120] 121. Expose an optical fiber panel with a cured adhesive layer coated on one end thereof, and allow ultraviolet rays to vertically enter from the uncoated end of the optical fiber panel to expose the adhesive layer at the input end.

[0121] In this step, a URE-2000B UV lithography system was used, and the UV exposure dose was set to 260 mJ / cm according to the thickness of the photoresist film and the size of the optical fiber. 2 .

[0122] This application has modified the existing exposure technology and does not require a mask. Instead, based on the property that "the core part has a strong ability to absorb ultraviolet rays, while the skin part has a strong ability to transmit ultraviolet rays", the photoresist irradiated by ultraviolet rays undergoes a cross-linking reaction to form a network structure that is insoluble in the developer.

[0123] 122. Post-bake the exposed sample to promote the cross-linking reaction in the exposed area and ensure that the colloid in the exposed area is fully cured.

[0124] In this step, the exposed optical fiber panel is placed on a hot plate with the uncoated end facing downward, and the process parameters are set as follows: baking temperature is 120° C. and baking time is 8 minutes.

[0125] 123. Immerse the post-baked sample into a developer with the help of tweezers to perform a developing process, so that the pattern of the adhesive layer is revealed, thereby obtaining a micro-well structure corresponding to the image transmission unit in the adhesive layer.

[0126] In this step, use tweezers to clamp the side wall of the sample (it is strictly forbidden to touch the two end faces) and immerse the optical fiber panel to be developed completely in the developer. Use a magnetic stirrer to allow the developer to fully react and dissolve the photoresist in the unexposed part. Due to the diffusion of components at the interface between the fiber core and the fiber sheath, after development, the glue layer presents a smooth arc-shaped micro-well-like three-dimensional structure from the center of the fiber core to the edge of the fiber sheath.

[0127] The developer used in this step is a mixture of xylene and isopropyl alcohol in a 3:1 volume ratio. The developer temperature is maintained at 23°C. The process parameters are: an immersion time of 15 seconds, and a magnetic stirrer speed of 150 rpm. This process involves a chemical reaction, which releases heat and causes the developer temperature to fluctuate. The developer is kept in water throughout the process to maintain a constant temperature of 23°C.

[0128] After development is completed, use tweezers to hold the side wall of the sample (do not touch the two end surfaces) to quickly remove the optical fiber panel from the developer, and immediately immerse it in deionized water to wash off the residual developer on the surface.

[0129] 13. Preparation of micro-well structure on the end face of optical fiber panel

[0130] 131. The developed optical fiber panel is immersed in an etchant for wet etching. Due to the corrosive nature of the etchant, the undeveloped portion, protected by the photoresist, is not corroded, while the developed portion, unprotected by the photoresist layer, undergoes a chemical reaction, resulting in a micro-well structure on the end face, thereby obtaining an optical fiber panel having a micro-well structure.

[0131] In this step, use tweezers to clamp the side wall of the sample (do not touch the two end surfaces) and immerse the optical fiber panel to be etched in a tank filled with etchant. Use a magnetic stirrer (30 rpm, 10 min) to allow the etchant to fully react with the exposed part of the optical fiber panel while discharging the heat and bubbles generated by the reaction in time.

[0132] The etchant is a hydrofluoric acid (HF) buffer, also known as a buffered hydrofluoric acid solution (BHF), which contains HF, NH4F, and H2O in a volume ratio of 1:6:10. Ammonium fluoride decomposes to produce HF, thereby maintaining a stable HF concentration. The process parameters set are: the water used for the BHF etchant is deionized water, the etchant temperature is maintained at 35°C, and the etching time is 10 minutes. This process involves a chemical reaction, which releases heat and causes the etchant temperature to fluctuate. The etchant is kept in water throughout the process to maintain a temperature of 35°C.

[0133] After etching is completed, use tweezers to clamp the side wall of the sample (do not touch the two end surfaces) to quickly remove the optical fiber panel from the etchant, and immediately immerse it in deionized water to wash off the residual etchant on the surface to prevent the residual alkali solution from corroding the substrate.

[0134] 132. The etched optical fiber panel is subjected to a wet degumming process, and the residual photoresist on the end face of the optical fiber panel is dissolved using a strong oxidizing solution to prepare a microlens-shaped optical fiber panel.

[0135] In this step, the strong oxidizing solution is a mixed solution of sulfuric acid (mass fraction 98%) and hydrogen peroxide in a volume ratio of 3:1. After ultrasonic cleaning for 20 minutes using an ultrasonic cleaning machine, the prepared microlens-shaped optical fiber panel is blown dry with high-purity nitrogen (purity 99.99%).

[0136] Metallographic microscopic observation of the microlens-shaped optical fiber panel produced above revealed a microwell structure on its surface: a regular honeycomb arrangement, with individual structures forming a smooth, curved microwell from the center of the optical fiber core to the edge of the fiber sheath. The opening diameter of the microwell structure was measured to be a maximum of 4.5μm and a minimum of 3.5μm, with a maximum well depth of 4.6μm and a minimum of 3.4μm. Defects in the microwell structure across the entire surface of the optical fiber panel were less than 15μm, meeting the desired target. A stereo microscope measured the resolution of the microlens-shaped optical fiber panel to be 120lp / mm, its transmittance to be 60% using a brightness detector, and its optical crosstalk rate to be 2.6% using an optical crosstalk meter.

[0137] Example 2: Preparation of a microlens-shaped optical fiber image invertor

[0138] 20. Preparation of optical fiber image invertor

[0139] 201. The preliminary preparation process of the optical fiber image inverter is the same as steps 101-104 in Example 1, and an optical fiber plate blank is obtained.

[0140] 202. The optical fiber plate blank is subjected to processes such as twisting, shape processing, and performance testing to obtain an optical fiber image inverter.

[0141] In this step, the fiber optic plate blank is twisted 180° at high temperature, with a twisting speed of 0.6° / s and a twisting temperature of 800°C to produce an optical fiber image invertor blank. The blank is then subjected to processing such as stepping, rounding, milling, and end-face polishing according to product appearance requirements. Performance tests are also conducted for field cleanliness, resolution, distortion, twist angle, and overall dimensions, resulting in an optical fiber image invertor that meets the specifications. The performance test results show that field cleanliness meets the maximum spot size of 25μm and the maximum chicken wire size of 0.2mm; resolution is 98lp / mm; serpentine distortion is 30μm, shear distortion is 20μm, and phase shift is 120μm; twist angle is 179.5°; and overall dimensional processing accuracy meets ±0.1mm.

[0142] 21. Preparation of highly uniform photoresist film layer

[0143] This step is the same as step 11 in Example 1.

[0144] 22. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0145] This step is the same as step 12 in Example 1.

[0146] 23. Preparation of micro-well structure on the end face of optical fiber image invertor

[0147] This step is the same as step 13 in Example 1;

[0148] Metallographic microscopic observation of the microlens-shaped optical fiber image inverter produced above revealed a microwell structure on the surface of the optical fiber panel: a honeycomb-like regular arrangement, with individual structures forming a smooth, curved microwell from the center of the optical fiber core to the edge of the fiber sheath. The opening diameter of the microwell structure was measured to be a maximum of 4.4μm and a minimum of 3.5μm, with a maximum well depth of 4.5μm and a minimum of 3.4μm. Defects in the microwell structure across the entire surface of the optical fiber panel were less than 15μm, meeting the desired target. Using a stereo microscope, the resolution of the microlens-shaped optical fiber image inverter was measured to be 119lp / mm, its transmittance was measured to be 56% using a brightness detector, and its optical crosstalk rate was measured to be 2.8% using an optical crosstalk rate tester.

[0149] Example 3: Preparation of Microlens-Shaped Optical Fiber Tapers

[0150] 30. Preparation of optical fiber tapers

[0151] 301. The preliminary preparation process of the optical fiber taper blank is the same as steps 101-104 in Example 1, to obtain an optical fiber blank.

[0152] 302. The optical fiber plate blank is subjected to processes such as stretching, shape processing, and performance testing to obtain an optical fiber taper.

[0153] In this step, the fiber optic blank undergoes a high-uniform stretching process at 120°C at a stretching speed of 1mm / s to produce an optical fiber taper blank. The blank is then subjected to various processes, including stepping, rounding, milling, and end-face polishing, to meet product appearance requirements. Performance testing for field cleanliness, resolution, distortion, taper ratio, and overall dimensions is then performed to produce an optical fiber taper that meets performance requirements. Performance testing results show that field cleanliness meets a maximum spot size of 90μm and a maximum chicken wire size of 0.2mm; resolution is 92lp / mm; serpentine distortion is 0.8% of the active area diameter, shear distortion is 25μm, barrel / pincushion distortion is 2% of the active area diameter, and phase shift is 210μm; and overall dimensional accuracy meets ±0.1mm.

[0154] 31. Preparation of Highly Uniform Photoresist Film

[0155] This step is the same as step 11 in Example 1.

[0156] 32. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0157] This step is the same as step 12 in Example 1.

[0158] 33. Preparation of Micro-well Structure on Tapered End of Optical Fiber

[0159] This step is the same as step 13 in Example 1;

[0160] Metallographic microscopic observation of the microlens-shaped optical fiber taper produced above revealed a microwell structure on the surface of the optical fiber panel: a regular honeycomb arrangement, with individual structures forming a smooth, curved microwell from the center of the optical fiber core to the edge of the fiber sheath. The measured opening diameter of the microwell structure ranged from a maximum of 4.2μm to a minimum of 3.4μm, and the well depth ranged from a maximum of 4.3μm to a minimum of 3.4μm. Defects in the microwell structure across the entire surface of the optical fiber panel were less than 15μm, meeting the desired target. A stereo microscope measured the resolution of the microlens-shaped optical fiber taper to be 118p / mm, its transmittance to be 54% using a brightness detector, and its optical crosstalk rate to be 2.9% using an optical crosstalk meter.

[0161] Example 4: Preparation of Microlens-Shaped Optical Fiber Panel (Glass Composition Different from Example 1)

[0162] 40. Preparation of optical fiber panels

[0163] The preparation steps of the optical fiber panel are the same as step 10 in Example 1, wherein the composition of the fiber core is as follows: 4% lead, multiple rare earth elements (Ce 4+ 、Eu 2+ 、Nd 3+)2%, titanium oxide + vanadium oxide + iron oxide 2%, SiO2 72%, Al2O3 3%, CaO 5%, Na2O 10%, MgO 1%, Fe2O3 1%; the composition of the fiber skin in molar ratio is: titanium oxide + vanadium oxide + iron oxide 1%, SiO2 79%, Al2O3 3%, CaO 5%, Na2O 10%, MgO 1%, Fe2O3 1%.

[0164] 41. Preparation of Highly Uniform Photoresist Film

[0165] This step and parameters are the same as step 11 in Example 1.

[0166] 42. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0167] This step and parameters are the same as step 12 in Example 1.

[0168] 43. Preparation of micro-well structure on the end face of optical fiber panel

[0169] 431. This step and parameters are the same as step 13 in Example 1, and a micro-lens-shaped optical fiber panel is obtained.

[0170] The microlens-shaped optical fiber panel produced above was observed under a metallographic microscope, and the microwell structure on the surface of the optical fiber panel was detected: it was arranged in a honeycomb pattern, and the individual structures were smooth arc-shaped microwells from the center of the optical fiber core to the edge of the fiber sheath. The opening diameter of the microwell structure was measured to be 3μm at most and 2μm at least, and the well depth was 3μm at most and 2μm at least. The maximum defect of the microwell structure on the entire surface of the optical fiber panel was 20μm. The resolution of the microlens-shaped optical fiber panel was measured to be 90lp / mm using a stereo microscope, its transmittance was 44% using a brightness detector, and its optical crosstalk rate was 3.8% using an optical crosstalk rate tester. The glass composition formula of the fiber core contains lead, multiple rare earth elements, and metal oxides such as titanium oxide, vanadium oxide, and iron oxide, which have the function of absorbing ultraviolet rays. Since the content of these components is lower than that of Example 1, the difference in ultraviolet transmittance between the fiber core and the fiber sheath is reduced, which in turn leads to a reduction in the exposure effect. The opening diameter and well depth of the microwell structure on the end face of the optical fiber panel are smaller than those of Example 1.

[0171] Example 5: Preparation of Microlens-Shaped Optical Fiber Panel (Static Spin Coating Parameters Different from Example 1)

[0172] 50. Preparation of optical fiber panels

[0173] This step and parameters are the same as step 10 in Example 1.

[0174] 51. Preparation of Highly Uniform Photoresist Film

[0175] The steps for preparing a highly uniform photoresist film layer are the same as step 11 in Example 1, wherein the spin coating process is performed by means of a spin coater, and the spin coating program set by the spin coater is: Step 1, the rotation speed is 350 r·min -1 , 3s; the second step, the speed is 2500r·min -1 , 3s; the third step, the speed is 3500r·min -1 The average thickness of the prepared photoresist film was 2 μm, with a thickness error of 5% and a standard deviation of 5%, indicating relatively stable consistency. The maximum surface defect was 20 μm.

[0176] 52. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0177] This step and parameters are the same as step 12 in Example 1.

[0178] 53. Preparation of micro-well structure on the end face of optical fiber panel

[0179] 531. This step and parameters are the same as step 13 in Example 1, and a micro-lens-shaped optical fiber panel is obtained.

[0180] The micro-lens-shaped optical fiber panel prepared above was observed under a metallographic microscope, and the micro-well structure on the surface of the optical fiber panel was detected: it was arranged in a honeycomb pattern, and a single structure was a smooth arc-shaped micro-well solid from the center of the optical fiber core to the edge of the fiber skin; the opening diameter of the micro-well structure was measured to be 4μm at most and 2μm at least, the well depth was 3μm at most and 2μm at least, and the maximum defect of the micro-well structure on the surface of the entire optical fiber panel was 18μm. The resolution of the micro-lens-shaped optical fiber panel was measured to be 93lp / mm using a stereo microscope, the transmittance was measured to be 47% using a brightness detector, and the optical crosstalk rate was measured to be 3.6% using an optical crosstalk rate tester. The time and rotation speed of each stage of static rotary coating were reduced compared to Example 1, resulting in an increase in glue thickness, which in turn caused the subsequent exposure, development and etching effects to be weakened compared to Example 1. Therefore, the opening diameter and well depth of the micro-well structure on the end face of the optical fiber panel were smaller than those in Example 1.

[0181] Example 6: Preparation of Microlens-Shaped Optical Fiber Panel (Pre-baking Parameters Different from Example 1)

[0182] 60. Preparation of optical fiber panels

[0183] This step and parameters are the same as step 10 in Example 1.

[0184] 61. Preparation of Highly Uniform Photoresist Film

[0185] The steps for preparing the highly uniform photoresist film layer are the same as step 11 in Example 1, wherein the baking temperature adopted in the pre-baking process is 100° C. and the baking time is 8 minutes.

[0186] 62. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0187] This step and parameters are the same as step 12 in Example 1.

[0188] 63. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0189] 631. This step and parameters are the same as step 13 in Example 1, and a micro-lens-shaped optical fiber panel is obtained.

[0190] The micro-lens-shaped optical fiber panel prepared above was observed under a metallographic microscope, and the micro-well structure on the surface of the optical fiber panel was detected: it was arranged in a honeycomb pattern, and a single structure was a smooth arc-shaped micro-well solid from the center of the optical fiber core to the edge of the fiber skin; the opening diameter of the micro-well structure was measured to be 3.5μm at most and 2.5μm at least, the well depth was 3.7μm at most and 2.3μm at least, and the maximum defect of the micro-well structure on the surface of the entire optical fiber panel was 18μm. The resolution of the micro-lens-shaped optical fiber panel was measured to be 98lp / mm using a stereo microscope, the transmittance was measured to be 49% using a brightness detector, and the optical crosstalk rate was measured to be 3.4% using an optical crosstalk rate tester. The increase in the pre-baking temperature compared to Example 1 resulted in a high degree of curing of the glue thickness, thereby weakening the subsequent exposure, development and etching effects. Therefore, the opening diameter and well depth of the micro-well structure on the end face of the optical fiber panel were smaller than those in Example 1.

[0191] Example 7: Preparation of Microlens-Shaped Optical Fiber Panel (Exposure Parameters Different from Example 1)

[0192] 70. Preparation of optical fiber panels

[0193] This step and parameters are the same as step 10 in Example 1.

[0194] 71. Preparation of Highly Uniform Photoresist Film

[0195] This step and parameters are the same as step 11 in Example 1.

[0196] 72. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0197] The preparation steps of the micro-well structure of the adhesive layer are the same as step 12 in Example 1, wherein the UV exposure dose is 300 mJ / cm 2 .

[0198] 73. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0199] 731. This step and parameters are the same as step 13 in Example 1, and a micro-lens-shaped optical fiber panel is obtained.

[0200] Metallographic microscopic observation of the microlens-shaped optical fiber panel produced above revealed a microwell structure on its surface: a regular honeycomb arrangement, with individual structures forming a smooth, curved microwell from the center of the optical fiber core to the edge of the fiber sheath. The opening diameter of the microwell structure was measured to be 3.8μm at its maximum and 2.6μm at its minimum, with a maximum well depth of 3.6μm and a minimum of 2.4μm. Defects in the microwell structure across the entire surface of the optical fiber panel were less than 18μm. A stereo microscope measured the resolution of the microlens-shaped optical fiber panel to be 101lp / mm, its transmittance to be 51% using a brightness detector, and its optical crosstalk rate to be 3.1% using an optical crosstalk meter. The increase in ultraviolet exposure dose enhances the exposure effect and promotes the cross-linking reaction in the negative photoresist. The exposed area increases relatively and the unexposed area decreases relatively. The exposed part is insoluble in the developer while the unexposed part is soluble in the developer. Therefore, the part soluble in the developer is reduced, so that the opening diameter and well depth of the micro-well structure on the end face of the optical fiber panel are smaller than those in Example 1.

[0201] Example 8: Preparation of Microlens-Shaped Optical Fiber Panel (Development Parameters Different from Example 1)

[0202] 80. Preparation of optical fiber panels

[0203] This step and parameters are the same as step 10 in Example 1.

[0204] 81. Preparation of Highly Uniform Photoresist Film

[0205] This step and parameters are the same as step 11 in Example 1.

[0206] 82. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0207] The preparation steps of the micro-well structure of the adhesive layer are the same as step 12 in Example 1, wherein, when performing immersion development, the development temperature is 23° C., the immersion time is 23 s, and the development is performed with a magnetic stirrer rotating at 150 rpm.

[0208] 83. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0209] 831. This step and parameters are the same as step 13 in Example 1, and a micro-lens-shaped optical fiber panel is obtained.

[0210] Metallographic microscopy observation of the microlens-shaped optical fiber panel produced above revealed a microwell structure on the surface of the optical fiber panel: arranged in a honeycomb pattern, with individual structures forming a smooth, curved microwell structure from the center of the optical fiber core to the edge of the fiber sheath. The measured opening diameter of the microwell structure ranged from a maximum of 4.7 μm to a minimum of 3.3 μm, the well depth ranged from a maximum of 4.8 μm to a minimum of 3.2 μm, and the maximum defect of the microwell structure on the entire surface of the optical fiber panel was 18 μm. The sidewall roughness reached a maximum of 26 nm. The resolution of the microlens-shaped optical fiber panel measured using a stereo microscope was 112 lp / mm, the transmittance was 55% using a brightness detector, and the optical crosstalk rate was 2.9% using an optical crosstalk rate tester. Increasing the development time further enhanced the development effect, as the corrosive effect of the developer increased the uncertainty and caused the dimensional fluctuation of the microwell structure to be greater. Furthermore, the corrosive effect of the developer on the sidewalls resulted in a relatively poorer sidewall roughness (maximum 26 nm) compared to Example 1 (maximum 21 nm).

[0211] Example 9: Preparation of a Microlens-Shaped Optical Fiber Panel (Wet Etching Parameters Different from Example 1)

[0212] 90. Preparation of optical fiber panels

[0213] This step and parameters are the same as step 10 in Example 1.

[0214] 91. Preparation of Highly Uniform Photoresist Film

[0215] This step and parameters are the same as step 11 in Example 1.

[0216] 92. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0217] This step and parameters are the same as step 12 in Example 1.

[0218] 93. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0219] 931. The preparation steps of the micro-well structure are the same as step 13 in Example 1, wherein, during wet etching, the temperature is maintained at 35°C and the etching time is 13 minutes to obtain a micro-lens-shaped optical fiber panel.

[0220] The microlens-shaped optical fiber panel prepared above was observed under a metallographic microscope, and the micro-well structure on the surface of the optical fiber panel was detected: it was arranged in a honeycomb pattern, and the individual structures were smooth arc-shaped micro-wells from the core center of the optical fiber to the edge of the fiber skin; the opening diameter of the micro-well structure was measured to be 6μm at most and 4μm at least, the well depth was 5.5μm at most and 3.5μm at least, and the maximum defect of the micro-well structure on the surface of the entire optical fiber panel was 20μm. The resolution of the micro-lens-shaped optical fiber panel was measured to be 122lp / mm using a stereo microscope, the transmittance was measured to be 61% using a brightness detector, and the optical crosstalk rate was measured to be 2.7% using an optical crosstalk rate tester. Increasing the wet etching time enhances the etching effect, so that the opening diameter and well depth of the etched micro-well structure are larger than those in Example 1.

[0221] Comparative Example 1: Preparation of Microlens-Shaped Optical Fiber Panel (Glass Composition Out of Range)

[0222] 100. Preparation of optical fiber panels

[0223] The preparation steps of the optical fiber panel are the same as step 10 in Example 1, wherein the glass composition formula of the fiber core is not doped with lead, rare earth elements (Ce 4+ 、Eu 2+ 、Nd 3+ ).

[0224] 101. Preparation of Highly Uniform Photoresist Film

[0225] This step and parameters are the same as step 11 in Example 1.

[0226] 102. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0227] This step and parameters are the same as step 12 in Example 1. Observation under a metallographic microscope revealed that no micro-well structure was formed in the adhesive layer.

[0228] 103. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0229] 1031. This step and parameters are the same as step 13 in Example 1.

[0230] Metallographic microscopy of the sample revealed no microwell structures on the fiber optic panel surface. A stereo microscope measured the sample's resolution at 80 lp / mm, its transmittance at 35% using a brightness detector, and its optical crosstalk at 4% using an optical crosstalk meter.

[0231] Since the fiber core is not doped with lead, rare earth elements (Ce 4+ 、Eu 2+ 、Nd 3+), there is little or no difference in ultraviolet transmittance between the fiber core and the fiber sheath, which does not support the generation of exposed areas and unexposed areas during exposure. Therefore, a micro-well structure cannot be prepared on the end face of the optical fiber panel, and the resolution, transmittance and optical crosstalk rate of the sample are worse than those of Example 1.

[0232] Comparative Example 2: Preparation of Microlens-Shaped Optical Fiber Panel (Static Spin Coating Parameters Out of Range)

[0233] 110. Preparation of optical fiber panels

[0234] This step and parameters are the same as step 10 in Example 1.

[0235] 111. Preparation of Highly Uniform Photoresist Film

[0236] The steps for preparing a highly uniform photoresist film layer are the same as step 11 in Example 1, wherein the spin coating process is performed by means of a spin coater, and the spin coating program set by the spin coater is: Step 1, rotation speed 300 r·min -1 , 2s; second step, speed 2300r·min -1 , 2s; Step 3, speed 3400r·min -1 The average thickness of the prepared photoresist film layer was 5 μm, with a thickness error of 5% and a standard deviation of 5%, indicating poor consistency.

[0237] 112. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0238] This step and parameters are the same as step 12 in Example 1.

[0239] 113. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0240] 1131. This step and parameters are the same as step 13 in Example 1.

[0241] The samples prepared above were observed under a metallographic microscope, and it was detected that there was no micro-well structure on the surface of the optical fiber panel.

[0242] The time of each stage of static spin coating is too short and the rotation speed is too low, resulting in an excessively thick adhesive layer, which in turn causes the subsequent exposure to be incomplete. Therefore, a micro-well structure cannot be prepared on the end face of the optical fiber panel, and the resolution, transmittance and optical crosstalk rate of the sample are worse than those of Example 1.

[0243] Comparative Example 3: Preparation of Microlens-Shaped Optical Fiber Panel (Pre-baking Parameters Out of Range)

[0244] 120. Preparation of optical fiber panels

[0245] This step and parameters are the same as step 10 in Example 1.

[0246] 121. Preparation of Highly Uniform Photoresist Film

[0247] The steps for preparing the highly uniform photoresist film layer are the same as step 11 in Example 1, wherein the pre-baking process adopts a baking temperature of 150° C. and a baking time of 15 minutes.

[0248] 122. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0249] This step and parameters are the same as step 12 in Example 1.

[0250] 123. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0251] 1231. This step and parameters are the same as step 13 in Example 1.

[0252] Metallographic microscopy of the sample prepared above revealed no microwell structure on the surface of the fiber optic panel. The resolution of the sample, measured using a stereo microscope, was 80 lp / mm. Its transmittance was 35% using a brightness detector, and its optical crosstalk rate was 4% using an optical crosstalk tester. Excessively high pre-baking temperatures and prolonged baking times destroyed the photosensitive agent during the pre-baking process, reducing the sensitivity of the photoresist and preventing crosslinking during subsequent exposure. Consequently, no microwell structure could be formed on the end face of the fiber optic panel. Consequently, the resolution, transmittance, and optical crosstalk rate of this sample were inferior to those of Example 1.

[0253] Comparative Example 4: Preparation of Microlens-Shaped Optical Fiber Panel (Exposure Parameters Out of Range)

[0254] 130. Preparation of optical fiber panels

[0255] This step and parameters are the same as step 10 in Example 1.

[0256] 131. Preparation of Highly Uniform Photoresist Film

[0257] This step and parameters are the same as step 11 in Example 1.

[0258] 132. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0259] The preparation steps of the micro-well structure of the adhesive layer are the same as step 12 in Example 1, wherein the UV exposure dose is 150 mJ / cm 2 .

[0260] 133. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0261] 1331. This step and parameters are the same as step 13 in Example 1.

[0262] Metallographic microscopy of the sample produced above revealed no microwell structures on the fiber optic faceplate surface. A stereo microscope measured the sample's resolution to be 80 lp / mm, its transmittance to be 35% using a brightness detector, and its optical crosstalk to be 4% using an optical crosstalk meter. The UV exposure dose was too low, resulting in insufficient exposure, and thus, no microwell structures were formed on the fiber optic faceplate end face. Consequently, the sample's resolution, transmittance, and optical crosstalk were inferior to those of Example 1.

[0263] Comparative Example 5: Preparation of Microlens-Shaped Optical Fiber Panel (Development Parameters Out of Range)

[0264] 140. Preparation of optical fiber panels

[0265] This step and parameters are the same as step 10 in Example 1.

[0266] 141. Preparation of Highly Uniform Photoresist Film

[0267] This step and parameters are the same as step 11 in Example 1.

[0268] 142. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0269] The preparation steps of the micro-well structure of the adhesive layer are the same as step 12 in Example 1, wherein, when performing immersion development, the development temperature is 35° C., the immersion time is 30 s, and the development is performed with a magnetic stirrer rotating at 150 rpm.

[0270] 143. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0271] 1431. This step and parameters are the same as step 13 in Example 1.

[0272] The samples prepared above were observed under a metallographic microscope to detect the micro-well structure on the surface of the optical fiber panel: they were arranged in a honeycomb pattern, but the single structure was an uneven arc from the core center of the optical fiber to the edge of the fiber skin, with poor morphology, and did not meet the expected goal. The resolution of the sample was measured to be 83lp / mm using a stereo microscope, its transmittance was measured to be 36% using a brightness detector, and its crosstalk rate was measured to be 3.9% using an optical crosstalk rate tester. The development temperature was too high and the immersion time was too long (overdevelopment), and the corrosive effect of the developer on the side wall caused the side wall roughness to be very poor. In addition, the immersion for too long caused the colloid to swell, and the morphology of the micro-well structure of the glue layer was poor, which resulted in the single micro-well structure prepared on the surface of the optical fiber panel being an uneven arc from the core center of the optical fiber to the edge of the fiber skin, with poor morphology. As a result, the resolution, transmittance and crosstalk rate of the sample were worse than those in Example 1.

[0273] Comparative Example 6: Preparation of Microlens-Shaped Optical Fiber Panel (Wet Etching Parameters Out of Range)

[0274] 150. Preparation of optical fiber panels

[0275] This step and parameters are the same as step 10 in Example 1.

[0276] 151. Preparation of Highly Uniform Photoresist Film

[0277] This step and parameters are the same as step 11 in Example 1.

[0278] 152. Preparation of micro-well structure corresponding to the image transmission unit in the adhesive layer

[0279] This step and parameters are the same as step 12 in Example 1.

[0280] 153. Preparation of Micro-well Structure on the End Face of Optical Fiber Panel

[0281] 1531. The preparation steps of the micro-well structure are the same as step 13 in Example 1, wherein the temperature is not controlled during wet etching and the etching time is 13 minutes. The above-prepared sample was observed under a metallographic microscope to detect the micro-well structure on the surface of the optical fiber panel: the overall arrangement was in a honeycomb shape, but the arrangement was irregular, and the etching was uneven; the lateral etching was excessive, and the sidewalls of the individual structures were not smooth arcs, but uneven, with poor morphology. The resolution of the sample was measured to be 81lp / mm using a stereo microscope, the transmittance was measured to be 36% using a brightness detector, and the optical crosstalk rate was measured to be 4% using an optical crosstalk rate tester.

[0282] Wet etching uses a chemical reaction between the etchant and the optical fiber imaging array to dissolve the portion that is not protected by the adhesive layer and is exposed to the etchant, thereby achieving the etching purpose. The chemical reaction releases heat. Failure to control the etchant temperature will cause the temperature to rise, resulting in excessive lateral etching and uneven side walls. In addition, failure to control the etchant temperature will lead to uneven temperature. The uneven temperature reacts to the chemical reaction, resulting in uneven etching. As a result, the resolution, transmittance and optical crosstalk rate of the sample are worse than those of Example 1.

[0283] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0284] For the microstructure described in the present invention, any modification, protection or passivation of the microstructure surface by simply depositing a film layer on the surface of the microstructure should be within the scope of protection of the present invention.

[0285] The numerical ranges described in the present invention include all values within the range, and include range values formed by any two values within the range. Different numerical values of the same indicator appearing in all embodiments of the present invention can be arbitrarily combined to form a range value.

[0286] The technical features in the claims and / or the specification of the present invention may be combined, and the manner of combination is not limited to the combination obtained by reference in the claims. The technical solutions obtained by combining the technical features in the claims and / or the specification are also within the scope of protection of the present invention.

[0287] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a fiber optic imaging array, characterized in that: The following steps are involved: S11 selects core glass rods and skin glass tubes based on machine learning; matches the obtained core glass rods and skin glass tubes and draws them into monofilaments; and draws black absorbing glass rods into light-absorbing glass filaments; S12: the monofilaments obtained in step S11 are arranged in a hexagonal closest packing pattern, the obtained light-absorbing glass fibers are inserted into the gaps in the hexagonal closest packing pattern, and the primary composite rods are obtained by bundling, and the obtained primary composite rods are drawn into primary multifilaments; S13: the primary multifilament obtained in step S12 is formed into a secondary composite rod by hexagonal close-packed arrangement, and then drawn into a secondary multifilament; S14: the secondary multifilaments obtained in step S13 are arranged in a hexagonal closest-packed manner, and bundled to obtain a regular hexagonal plate segment; S15: hot-melt-pressing the panel segments obtained in step S14 and processing the optical fiber panel blanks to obtain optical fiber panel blanks; S16: The optical fiber plate blank obtained in step S15 is post-processed to obtain the optical fiber image transmission array.

2. The method for preparing a microlens-shaped optical fiber image transmission array according to claim 1, wherein: In step S11, the drawing temperature of the monofilament is 750-770°C, and the rod-drawing speed is 25-30 mm / min; the drawing temperature of the light-absorbing glass filament is 800-820°C, and the rod-drawing speed is 22-27 mm / min; the drawing temperature of the interstitial filament is 700-720°C, and the rod-drawing speed is 28-33 mm / min; the diameter of the monofilament is 4.3±0.1 mm; the diameter of the light-absorbing glass filament is 0.3±0.05 mm; the diameter of the interstitial filament is 0.2±0.05 mm; in step S12, the drawing temperature is 760-780°C, and the rod-drawing speed is 20-23 mm / min; the opposite side dimension of the primary multifilament is 2.3±0.1 mm. In step S13, the drawing temperature is 750-770°C, the rod lowering speed is 18-20 mm / min; the opposite side dimension of the secondary multifilament is 1.8±0.1 mm; in step S15, the hot melt pressing temperature is 620-630°C, the time is 80-150 min, the pressure is 10-15 MPa, and the pressing scale is 3-6 mm.

3. The method for preparing a microlens-shaped optical fiber image transmission array according to claim 1, wherein: In step S16, the post-processing includes the following steps: The fiber optic panel is obtained by rounding the fiber optic plate blank and then cutting, grinding and polishing.

4. The method for preparing a microlens-shaped optical fiber image transmission array according to claim 1, wherein: In step S16, the post-processing includes the following steps: a1 twists the fiber optic plate blank to obtain a fiber optic image invertor blank; b1 Grind and polish the end face of the fiber optic image inverter blank. Grind with a grinder for 1-2 hours and polish with a polisher for 1.5-3 hours. After passing the inspection, the fiber optic image inverter is obtained.

5. The method for preparing a microlens-shaped optical fiber image transmission array according to claim 1, wherein: In step S16, the post-processing includes the following steps: a2 stretches the optical fiber plate blank and then cuts it into two to obtain an optical fiber taper blank; b2 Grind and polish the end face of the fiber optic taper blank. Grind with a grinder for 1-2 hours and polish with a polisher for 1.5-3 hours. After passing the performance test, the fiber optic taper is obtained.

6. A fiber optic imaging array, characterized in that: It comprises an output end, an input end and an optical fiber portion arranged between the output end and the input end; the optical fiber imaging array is manufactured by the method according to any one of claims 1-5.

7. A method for preparing a microlens-shaped optical fiber image transmission array, characterized in that: The following steps are involved: S21: uniformly coating the photoresist on the input end of the optical fiber imaging array by static spin coating, and then removing the solvent in the photoresist by pre-baking to form a uniform film, enhance the adhesion to the substrate, and solidify the photoresist film layer to avoid problems in subsequent exposure and development, thereby obtaining a highly uniform photoresist film layer with low surface defects, micron-level thickness, and stable consistency; S22: exposing the optical fiber imaging array obtained in step S21, with one end surface coated with a cured adhesive layer, so that the exposed and unexposed areas correspond to the imaging units of the optical fiber imaging array one by one; then performing post-baking to ensure that the adhesive layer in the exposed area is fully cured; and then performing development to reveal the adhesive layer pattern. In step S23 , the optical fiber imaging array developed in step S22 is immersed in an etchant for wet etching, so that the end face presents a micro-well structure, thereby obtaining the micro-lens-shaped optical fiber imaging array.

8. The method for preparing a microlens-shaped optical fiber image transmission array according to claim 7, wherein: In step S21, the photoresist is a UV negative photoresist for 365nm exposure.

9. A micro-lens optical fiber image transmission array, characterized in that: Its end face has a plurality of micro-well structures, the opening diameter of the micro-well structure is 3-6μm at most and 2-4μm at least, the well depth is 3-5.5μm at most and 2-3.5μm at least; the micro-lens-shaped optical fiber imaging array is made by the method described in any one of claims 1-8.

10. An optical system, characterized in that: The optical system includes the microlens-shaped optical fiber imaging array according to claim 9.

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