Micro-structure fiber image-conversion element, its preparation method and application

Abstract

The present application relates to a kind of micro concave structure optical fiber image transmission element and its preparation method and application, the method comprises: the core material glass rod and the skin material glass tube are drawn into primary monofilament;Black absorption glass rod is drawn into light absorption glass gap filament;Skin glass rod is drawn into skin glass gap filament;Primary monofilament is arranged in hexagonal closest packing, light absorption glass gap filament and skin glass gap filament are inserted into primary monofilament gap in sequence, obtain primary composite rod, primary composite rod is drawn into primary multifilament;Primary multifilament is arranged in hexagonal closest packing into secondary composite rod, and is drawn into secondary multifilament;Secondary multifilament is arranged in hexagonal closest packing, and after fixed-length cutting, it is arranged into board section, and the board section is formed into fused fiber rod by hot melt compression molding;Fused fiber rod is post-processed into optical fiber image transmission element;Optical fiber image transmission element is etched by ion beam under vacuum.The present application is etched out groove structure by adjusting the composition of the core and skin layer glass inside optical fiber image transmission element and ion beam bombardment on the input end face of optical fiber image transmission element.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical elements, and particularly relates to a micro-concave structure optical fiber image transmission element and a preparation method and application thereof. BACKGROUND

[0002] The optical fiber image transmission element is an imaging technology based on an optical fiber array, which mainly transmits image signals from an input end to a detector or an imaging system through optical fibers. At present, the optical fiber image transmission element is widely used in multiple high-precision and high-sensitivity fields, such as low-light-level night vision, high-energy detection, scintillator glass, and transmission electron microscopy. In the field of low-light-level night vision, the optical fiber image transmission element, combined with an imaging system under low light, realizes effective transmission of weak light signals and improves the clarity and visualization of images. In the field of high-energy detection, the optical fiber image transmission element works cooperatively with scintillator materials to capture and transmit fluorescent signals generated by high-energy radiation (such as gamma rays and particle beams), helping to realize high-precision radiation imaging and detection. This technology has important applications in nuclear medicine, radiation monitoring, and particle physics experiments. In the field of scintillator glass, the optical fiber image transmission element is used to transmit light signals generated by scintillator materials to a detection system and is widely used in radiation detection and imaging systems. In transmission electron microscopy, the optical fiber image transmission element helps realize high-resolution image transmission, improves imaging accuracy and signal processing speed, and especially shows its advantages in nanoscale high-resolution imaging. Overall, the optical fiber image transmission element provides important support in multiple technical fields due to its efficient image transmission capability and excellent performance, and promotes the technological progress and application development in related fields.

[0003] The optical fiber image transmission element is composed of millions of precisely arranged optical fibers, each of which is composed of a core glass 4a and a cladding glass 3a, forming a total reflection structure to ensure high-fidelity image transmission. By coating the surface of the optical fiber image transmission element with fluorescent powder 2a, electro-optical conversion can be achieved, and incident light 1a is transmitted to the inside of the optical fiber. When the incident end of the optical fiber image transmission element is a plane, the light emitted from the fluorescent powder 2a propagates in various directions, such as Figure 1As shown, part of the light rays may enter other optical fibers, causing crosstalk, light loss, and ultimately affecting image resolution. To improve the efficiency of light capture, the incident end can be processed into a groove structure with a certain depth. This structure can increase the contact angle and receiving area of the optical fiber with the incident light, optimize the reception of optical fiber arrays for different angles of incident light, and reduce signal loss caused by deviation in the incident angle. In addition, the groove structure can also enhance the bonding force between the fluorescent powder 1b and the surface of the optical fiber image transmission element. However, if the groove surface is not uniform, problems such as poor surface precision and high roughness may occur, which will also affect the transmission efficiency of the light. Overall, the design of the groove structure helps to improve the light transmission performance of the optical fiber image transmission element, especially in complex light source environments and high-precision imaging tasks, which can significantly improve the image quality and system sensitivity. SUMMARY

[0004] Therefore, the main purpose of the present application is to provide a micro-groove structure optical fiber image transmission element, its preparation method and application, and to solve the technical problem of improving the image resolution by adjusting the composition of the core and cladding glass inside the optical fiber image transmission element, making the hardness of the core glass lower than that of the cladding glass, using the hardness difference between the two, and etching a groove structure with a certain depth on the input end face of the optical fiber image transmission element by ion beam bombardment technology, optimizing the uniformity of the groove structure surface etching process.

[0005] The purpose of the present application and the technical problems solved thereby are achieved by the following technical solutions. The present application provides a preparation method of a micro-groove structure optical fiber image transmission element, comprising the following steps:

[0006] S1: match the core material glass rod and the cladding material glass tube to draw a primary monofilament; draw a black absorbing glass gap filament from a black absorbing glass rod; draw a cladding glass gap filament from a cladding glass rod; the core material glass rod comprises the following components in mass percentage: SiO2 34-46%, B2O3 16-25%, ZnO 5-11%, LaO 12-17%, Li2O 2-5%, Bi2O3 5-10%, TiO2 5-18%, CaO 4-15%; the cladding material glass tube comprises the following components: SiO2 50-60%, Al2O3 0-3%, CaO 5-13%, B2O3 10-22%, K2O 18-30%, Na2O3-15%;

[0007] S2: hexagonally arrange the primary monofilament, insert the light absorbing glass gap filament and the cladding glass gap filament into the gap of the primary monofilament in sequence to obtain a primary composite rod, and draw the primary composite rod into a primary multifilament;

[0008] S3: hexagonally arrange the primary multifilament into a secondary composite rod, and draw the secondary composite rod into a secondary multifilament;

[0009] S4 hexagonal closest packing of secondary multifilament, and cut to size after arranging into 70-110mm plate segment, the plate segment is formed by hot melt molding into a melt fiber rod;

[0010] S5 melt fiber rod is processed into an optical fiber image element by post-processing;

[0011] S6 the obtained optical fiber image element is subjected to ion beam etching under vacuum conditions, thereby obtaining the micro-concave structure optical fiber image element.

[0012] The purposes of the present application and the technical problems thereof are further achieved by the following technical measures.

[0013] Preferably, in the preparation method of the micro-concave structure optical fiber image element, in step S1, the drawing temperature of the primary monofilament is 790-850℃, and the time is 30-120 minutes; the drawing temperature of the light-absorbing glass gap filament is 820℃-860℃, and the time is 30-100 minutes; the drawing temperature of the skin glass gap filament is 750℃-800℃, and the time is 45-120 minutes.

[0014] Preferably, in the preparation method of the micro-concave structure optical fiber image element, in step S1, the diameter of the primary monofilament is 2-4mm; the diameter of the light-absorbing glass gap filament is 0.3-0.5mm; and the diameter of the skin glass gap filament is 0.3-0.5mm.

[0015] Preferably, in the preparation method of the micro-concave structure optical fiber image element, in step S2, the drawing temperature is 760℃-840℃, and the time is 35-130 minutes; and the opposite side size of the primary multifilament is 1.00-1.08mm.

[0016] Preferably, in the preparation method of the micro-concave structure optical fiber image element, in step S3, the drawing temperature is 760℃-830℃, and the time is 50-160 minutes; and the opposite side size of the secondary multifilament is 0.78-0.85mm.

[0017] Preferably, in the preparation method of the micro-concave structure optical fiber image element, in step S4, the cutting size of the plate segment is 70-110mm; the temperature of the hot melt molding is 500℃-550℃, the time is 120-210min, and the pressure is 45-100N.

[0018] Preferably, in the preparation method of the micro-concave structure optical fiber image element, in step S5, the post-processing comprises the following steps:

[0019] The melt fiber rod is rounded, and then cut, ground and polished to obtain an optical fiber panel.

[0020] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step S5, the cutting length of the fused fiber rod is 17-35 mm, the grinding time is 1.5-2.5 h, and the polishing time is 2-4 h.

[0021] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step S5, the post-processing comprises the following steps:

[0022] a1 twisting the fused fiber rod to obtain a fiber inverter blank;

[0023] b1 grinding and polishing the end face of the fiber inverter blank, grinding for 1.5-2.5 h by a grinder and polishing for 2-4 h by a polisher, and obtaining a fiber inverter after performance detection.

[0024] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step a1, the twisting temperature is 760-800 ℃, the twisting angle is 179°-181°, and the twisting time is 60-110 minutes.

[0025] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step b1, the grinding time is 1.5-2.5 h, and the polishing time is 2-4 h.

[0026] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step S5, the post-processing comprises the following steps:

[0027] a2 stretching the fused fiber rod, cutting it and then dividing it into two parts to obtain a fiber light cone blank;

[0028] b2 grinding and polishing the end face of the fiber light cone blank, grinding for 1.5-2.5 h by a grinder and polishing for 2-4 h by a polisher, and obtaining a fiber light cone after performance detection.

[0029] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step a2, the stretching temperature is 725-760 ℃, the stretching time is 40-140 minutes, and the stretching cone ratio is 2.5:1.

[0030] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step b2, the grinding time is 1.5-2.5 h, and the polishing time is 2-4 h.

[0031] Preferably, in the method for preparing the micro-structure fiber image element as described above, in step S6, the operation parameters of the ion beam etching are set as follows: the vacuum degree is 10 -4 -10 -6Pa, ion beam energy is 250-600eV, Ar flow is 8-35sccm, direct current voltage is 700-1100V, etching angle is 0°.

[0032] The purposes and technical problems of the present application can also be further achieved by the following technical measures. The present application provides a micro-concave structure optical fiber image transmission element, which has an input end surface for receiving and transmitting incident light and an opposite output end surface, and the input end surface has a groove structure; the etching depth of the groove structure is 3.05-3.3mm, the surface accuracy is 0.34-0.46λ, and the roughness is 2.12-2.21nm.

[0033] The purposes and technical problems of the present application can also be further achieved by the following technical measures. The present application provides an optical system, which comprises the above-mentioned micro-concave structure optical fiber image transmission element.

[0034] By the above technical solution, the present application provides a micro-concave structure optical fiber image transmission element, a preparation method and application thereof, which have at least the following advantages:

[0035] The micro-concave structure optical fiber image transmission element provided by the present application adjusts the composition of the core and cladding glass inside the optical fiber image transmission element, so that the hardness of the core glass is lower than that of the cladding glass. By using the hardness difference between the two, a groove structure with a certain depth is etched on the input end surface of the optical fiber image transmission element by ion beam bombardment technology. The uniformity of the groove structure surface etching process is optimized, the surface accuracy of the optical fiber image transmission element is improved, and the roughness is reduced. The present application uses this preparation method to make the prepared optical fiber image transmission element provide more excellent performance in high-end applications such as low-light night vision and high-energy detection, so as to promote the development of related technical fields.

[0036] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the description, the following will be described in detail with the preferred embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of an optical fiber with a flat input end in the prior art;

[0038] 1a-Incident light; 2a-Fluorescent powder; 3a-Cladding glass; 4a-Core glass;

[0039] Figure 2 It is a schematic diagram of the input end groove structure of the optical fiber image transmission element of the embodiment of the present application.

[0040] 1b-Fluorescent powder; 2b-Core glass; 3b-Cladding glass. DETAILED DESCRIPTION

[0041] To further clarify the technical means and effects taken by the present application to achieve the intended purpose, the following describes the micro-concave structure fiber image transmission element, its preparation method and application, its specific implementation, structure, features and effects according to the present application in detail. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0042] The following materials or reagents, unless otherwise specified, are commercially available.

[0043] Some embodiments of the present application provide a preparation method of a micro-concave structure fiber image transmission element, comprising the following steps:

[0044] I. Preparation of fiber image transmission element

[0045] According to the mass ratio in Table 1, the silica, boron oxide, zinc oxide, calcium oxide, lithium oxide, titanium oxide, lanthanum oxide and bismuth oxide powders are weighed, mixed uniformly, and then put into a platinum crucible. The temperature is heated to 1500-1600℃. If the temperature is higher than 1600℃, the glass liquid may be excessively volatile, causing the loss of raw materials, and even changing the glass composition ratio and affecting its performance. If the temperature is lower than 1500℃, the bubbles in the glass liquid are difficult to fully discharge and remain in the glass, which will reduce the transparency of the glass and affect the transmission effect of the optical fiber image element on the optical signal and the optical performance. The components are completely melted, and the temperature is maintained for 5-8 hours. If the holding time is greater than 8 hours, the volatile components in the glass liquid may be excessively lost, affecting the chemical uniformity and optical performance of the glass. Conversely, if the holding time is less than 5 hours, the bubbles and impurities cannot be fully discharged, and pores or stripes will remain in the glass. During this process, continuous and slow stirring is carried out at a stirring speed of 8-12 rpm to ensure uniform fusion of the components. If the stirring speed is greater than 12 rpm, excessive shear force may be introduced, causing new bubbles to be involved in the glass liquid and affecting the stability of the glass composition. If the stirring speed is less than 8 rpm, the glass liquid will not be uniformly mixed, and the bubbles will be difficult to effectively float out, ultimately affecting the optical performance and mechanical strength of the glass. Then, the molten glass liquid is discharged through the discharge port and formed into a glass rod with a diameter of 28-35 mm. The thickness of the glass rod affects the matching of the glass tube. After being maintained at 640-660℃ for 2-3 hours, the power is turned off, and it is naturally cooled to room temperature to complete the annealing process, and finally the core material glass rod is obtained. If the annealing temperature is higher than 660℃, the internal stress of the glass can be quickly relaxed, but the surface of the glass may be softened and deformed, and even the optical precision and dimensional stability may be affected. If the annealing temperature is lower than 640℃, the internal stress of the glass cannot be fully eliminated. At the same time, if the annealing time is less than 2 hours, the residual stress cannot be completely released, which may cause the glass to deform, crack or have poor optical uniformity during subsequent processing or use. If the annealing time is greater than 3 hours, although the stress can be fully eliminated, the production efficiency will be reduced.

[0046] The silica, alumina, calcium oxide, sodium oxide and potassium oxide powders are weighed according to the mass ratio in Table 1, mixed well using a mixer, and placed in a platinum crucible. The mixture is heated to 1500-1600°C. If the temperature is higher than 1600°C, the glass liquid may be excessively volatilized, causing loss of raw materials and even changing the glass composition ratio and affecting its performance. If the temperature is lower than 1500°C, the bubbles in the glass liquid are difficult to fully discharge and remain in the glass. The temperature is maintained for 5-9 hours. If the temperature is maintained for more than 9 hours, the volatile components in the glass liquid may be excessively lost, affecting the chemical uniformity of the glass. Conversely, if the temperature is maintained for less than 5 hours, the bubbles and impurities cannot be fully discharged, and pores or stripes may remain in the glass. The stirring paddle speed is preferably 9-12 rpm to ensure sufficient mixing. If the stirring paddle speed is greater than 12 rpm, excessive shear force may be introduced, causing new bubbles to be entrained in the glass liquid and affecting the stability of the glass composition. If the stirring paddle speed is less than 9 rpm, the glass liquid is not mixed uniformly, and the bubbles are difficult to effectively float and discharge. After being heated to 1500-1600°C, the molten glass liquid is drawn into a glass tube matching the core rod using a mechanical hand, and the inner diameter of the glass tube is 30-32 mm. The size also determines the matching with the glass rod. The glass tube is placed in an annealing furnace and heated to 570-600°C, and then naturally cooled to room temperature after being maintained for 3-4 hours, so as to complete annealing and finally obtain a cladding tube. If the annealing temperature is higher than 600°C, the internal stress of the glass can be quickly relaxed, but the surface of the glass may be softened and deformed, and even the dimensional stability may be affected. If the annealing temperature is lower than 570°C, the internal stress of the glass cannot be fully eliminated. If the annealing time is less than 2 hours, the residual stress cannot be completely released, which may cause deformation and cracking of the glass during subsequent processing or use. If the annealing time is greater than 3 hours, although the stress can be fully eliminated, the production efficiency is reduced. The thickness of the cladding tube is 4.3-5.1 mm, and the outer diameter is 34.8-36.8 mm.

[0047] Subsequently, the core glass and the cladding glass are respectively made into samples with a length of 50 mm, a width of 50 mm and a height of 10 mm, and the hardness thereof is respectively measured using an HV-100 Vickers hardness tester.

[0048] Table 1: Glass material composition of optical fiber image transmission element

[0049]

[0050] Silica (SiO2) forms the main body of the glass framework and plays a crucial role in it. If the SiO2 content is too low (e.g., less than 34% or less than 50%), the chemical stability of the glass will decrease. When the SiO2 content is too high (e.g., greater than 46% or greater than 60%), the high-temperature viscosity of the glass will increase significantly, leading to excessively high melting temperatures.

[0051] Aluminum oxide (Al₂O₃) is an intermediate oxide in glass. 3+ Al₂O₃ exists in two coordination states: tetrahedral and octahedral. When oxygen is abundant in the glass, aluminum-oxygen tetrahedra [AlO₄] are formed, which can form a continuous network with silicon-oxygen tetrahedra, enhancing the stability of the glass structure. When oxygen is insufficient in the glass, aluminum-oxygen octahedrons [AlO₆] are formed, existing as network exogenous bodies in the vacancies of the silicon-oxygen network. Within a certain content range, Al₂O₃ can synergistically form the main body of the glass network with SiO₂. However, if the Al₂O₃ content is too high (e.g., greater than 3%), the glass melting temperature will be too high.

[0052] Boron oxide (B₂O₃) is a glass-forming oxide and a component of the glass framework. It is also an effective flux that reduces the viscosity of molten glass. Its structural components are boron-oxygen trigonal [BO₃] and boron-oxygen tetrahedron [BO₄]. Under different conditions, boron may exist in the form of trigonal [BO₃] or boron-oxygen tetrahedron [BO₄]. Under high-temperature melting conditions, boron-oxygen tetrahedra are generally difficult to form, and it mostly exists in trihedral form. However, at low temperatures, under specific conditions, boron... 3+ B₂O₃ tends to capture free oxygen to form tetrahedra, resulting in a denser structure and thus increasing the low-temperature viscosity of the glass. Because B₂O₃ has the property of decreasing glass viscosity at high temperatures and increasing it at low temperatures, it is also a major component in reducing the refractive index of glass, which determines its relatively narrow content range. If the content is too high (e.g., greater than 25% or greater than 22%), the tendency for phase separation in the glass increases. When the B₂O₃ content is too low (e.g., less than 16% or less than 10%), the stability of the glass's network structure decreases, leading to excessively high high-temperature viscosity and difficulties in melting.

[0053] Zinc oxide (ZnO) is an oxide used to regulate the melting temperature and crystallization properties of glass. If the ZnO content is too high (e.g., greater than 11%), the chemical stability of the glass decreases, while the tendency for crystallization increases. Conversely, if the ZnO content is too low (e.g., less than 5%), it causes instability in the glass network structure.

[0054] Lanthanum oxide (La₂O₃) is a lanthanide rare earth oxide that can significantly improve the refractive index of glass. Excessive La₂O₃ content (e.g., greater than 17%) increases the coefficient of thermal expansion of the glass. Conversely, insufficient La₂O₃ content (e.g., less than 12%) results in a less effective increase in the glass's refractive index.

[0055] Lithia (Li2O) is an extra-network oxide. If the Li2O content is too high (e.g., greater than 5%), the glass crystallization tendency increases. If the Li2O content is too low (e.g., less than 2%), it is difficult to effectively reduce the melting temperature, resulting in a high glass melting temperature.

[0056] Bismuth oxide (Bi2O3) is easily polarized and deformed, and is easily inserted into the glass network space, acting as a glass former, which can effectively improve the chemical stability and refractive index of the glass. If the Bi2O3 content is too low (e.g., less than 5%), the core glass will have poor medium temperature stability, resulting in severe deformation of the glass during the melting and pressing process, which cannot maintain a circular shape, and the structural stability is reduced, which further aggravates the grid defects. When the Bi2O3 content is too high (e.g., greater than 10%), it will reduce the viscoelastic matching degree of the core and skin glass materials at high temperature, increase the thermal stress, and even cause collapse and explosion.

[0057] Titanium oxide (TiO2) is used to adjust the chemical resistance and crystallization of the glass. When the TiO2 content is too high (e.g., greater than 18%), the chemical resistance of the glass will decrease, and the crystallization tendency will increase. When the TiO2 content is too low (e.g., less than 5%), the glass may not have sufficient resistance to crystallization, which can lead to easier crystallization.

[0058] Calcium oxide (CaO) is an extra-network oxide of the glass structure. If the CaO content is too high (e.g., greater than 13%), the chemical resistance of the glass will decrease, and the glass crystallization tendency will increase. When the CaO content is too low (e.g., less than 5%), the network structure of the glass is unstable, which can lead to a decrease in glass strength and hardness.

[0059] Sodium oxide (Na2O) is an extra-network oxide of the glass structure. When the Na2O content is too high (e.g., greater than 15%), the thermal expansion coefficient of the glass will increase. If the Na2O content is too low (e.g., less than 3%), the melting temperature of the glass will increase, resulting in an increase in production energy consumption.

[0060] Potassium oxide (K2O) is an extra-network oxide of the glass structure. If the K2O content is too high (e.g., greater than 30%), the thermal expansion coefficient of the glass will increase. When the K2O content is too low (e.g., less than 18%), the thermal expansion coefficient of the glass may decrease, and the chemical stability will decrease.

[0061] The core glass rod and the cladding glass tube are matched and then drawn into a primary single fiber with a diameter of 2-4 mm at a temperature of 790-850 °C. If the temperature is higher than 850 °C, the glass is excessively softened, and it is difficult to accurately control the diameter of the fiber during drawing, and the fiber may be broken or adhered. If the temperature is lower than 790 °C, the viscosity of the glass is too high, the drawing resistance is increased, the internal stress of the fiber is increased, and the fiber is easily broken. In addition, the glass flowability is insufficient at low temperature, which may result in poor interfacial bonding between the core layer and the cladding layer, and affect the light transmission performance. The black absorbing glass rod is drawn into an optical absorbing glass gap fiber with a diameter of 0.3-0.5 mm at a temperature of 820-860 °C for 30-100 minutes. If the temperature is higher than 860 °C, the viscosity of the glass is too low, and the fiber diameter is not uniform. If the temperature is lower than 820 °C, the viscosity of the glass is too high, the drawing resistance is increased, the internal stress of the fiber is increased, the mechanical strength is reduced, and micro-cracks and other defects may be generated. If the drawing time is greater than 100 minutes, the black absorbing glass rod is excessively softened at high temperature, and the fiber diameter is not uniform or even broken. If the drawing time is less than 30 minutes, the glass is not sufficiently stretched, the internal stress is accumulated, and the surface defects are increased. The cladding glass rod is drawn into a cladding glass gap fiber with a diameter of 0.3-0.5 mm at a temperature of 750-800 °C for 45-120 minutes. If the temperature is higher than 800 °C, the viscosity of the glass is significantly reduced, the fiber diameter is fluctuated, the surface is not smooth, or even the fiber is broken. If the temperature is lower than 750 °C, the viscosity of the glass is too high, the drawing resistance is increased, and the internal stress of the fiber is increased. If the drawing time is greater than 120 minutes, the fiber is excessively softened at high temperature, and the fiber diameter is not uniform or even broken. If the drawing time is less than 45 minutes, the glass is not sufficiently stretched, the internal stress is accumulated, and the surface quality defects are increased.

[0062] The primary monofilament is arranged in a hexagonal closest packing, the light-absorbing glass gap filaments and the skin glass gap filaments are inserted into the gaps of the primary monofilament in sequence to obtain a primary composite rod, and the primary composite rod is drawn into a primary multifilament with a pair of edge size of 1.00-1.08 mm after being subjected to a temperature of 760-840 ℃ for 35-130 minutes. If the temperature is higher than 840 ℃, the viscosity of the glass is reduced, which can easily cause problems such as unstable diameter and breakage of the primary composite rod. If the temperature is lower than 760 ℃, the viscosity of the primary composite rod is too large, which can increase the drawing resistance and the internal stress. If the drawing time is longer than 130 minutes, the primary composite rod is excessively softened in the high-temperature environment, which can also cause problems such as uneven diameter or breakage. Conversely, if the drawing time is less than 35 minutes, the internal stress of the primary composite rod is accumulated due to insufficient stretching, and the surface quality is reduced.

[0063] The primary multifilament is arranged in a hexagonal closest packing to become a secondary composite rod, and the secondary composite rod is drawn into a secondary multifilament with a pair of edge size of 0.78-0.85 mm after being subjected to a temperature of 760-830 ℃ for 50-160 minutes. If the temperature is higher than 830 ℃, the viscosity of the glass is significantly reduced, which can cause problems such as unstable diameter and breakage of the primary multifilament. If the temperature is lower than 760 ℃, the viscosity of the primary multifilament is too large, which can increase the drawing resistance and the internal stress. If the drawing time is longer than 160 minutes, the primary multifilament is excessively softened in the high-temperature environment, which can easily cause problems such as uneven diameter or breakage. Conversely, if the drawing time is less than 50 minutes, the internal stress of the primary multifilament is accumulated due to insufficient stretching, and the surface quality is reduced.

[0064] The secondary multifilament is arranged in a hexagonal closest packing, and the arranged plate segment with a length of 70-110 mm is cut to a fixed length. The length of the plate segment is determined according to the size of the furnace cavity of the fusion pressing equipment and the production requirements. The plate segment is subjected to a process with a temperature of 500-550 ℃, a time of 120-210 min, and a pressure of 45-100 N. If the temperature is higher than 550 ℃, the fusion pressing temperature is too high, which can cause the glass to be excessively softened, the glass to be deformed or adhered during fusion, the boundary of the multifilament to be deformed, the internal structure to be non-uniform, and the optical performance and mechanical strength to be affected. If the temperature is lower than 500 ℃, the temperature is too low, which can cause the glass to be insufficiently fused between the gaps, interface defects or residual stress to be generated, and the density and light transmittance of the glass rod to be reduced. If the fusion pressing time is longer than 210 min, the glass is excessively softened in the high-temperature environment, which can cause the glass to be excessively fused and deformed, the optical uniformity and mechanical strength to be reduced. If the fusion pressing time is less than 120 min, the glass is insufficiently fused between the gaps, interface defects or residual stress are generated. If the fusion pressing pressure is higher than 100 N, the glass fiber is excessively extruded and deformed, which can damage the original fiber structure and cause internal stress concentration. If the fusion pressing pressure is lower than 45 N, the space between the glass fibers cannot be sufficiently removed, which can cause pores to exist in the fusion interface or the combination to be not tight, and the density and mechanical strength of the glass rod to be reduced. After hot fusion pressing, a fused fiber rod is formed.

[0065] After the melt fiber rod is rounded, it is cut, ground, and polished, wherein the melt fiber rod is cut to a length of 17-35 mm using a cutting machine, the cutting length is set by considering the maximum processing range of the cutting machine and the actual cutting requirement, the grinder grinds for 1.5-2.5 h, and the polisher polishes for 2-4 h to obtain an optical fiber panel, wherein when the grinding time is greater than 2.5 h, the end surface of the melt fiber rod is excessively removed, which may damage the size accuracy of the fiber rod and introduce deep scratches; when the grinding time is less than 1.5 h, the surface defects cannot be effectively eliminated, which affects the subsequent polishing effect. Similarly, when the polishing time is greater than 4 h, local overheating or excessive material loss may occur, which causes uneven surface morphology; when the polishing time is less than 2 h, it is difficult to completely remove the grinding marks, which affects the surface finish and optical performance.

[0066] The melt fiber rod is subjected to a high-temperature torsion process, and is twisted by a high-precision twisting machine. The high-temperature torsion temperature is set to 760-800℃. When the torsion temperature is higher than 800℃, the glass softens excessively, the fiber structure is deformed, and the original optical transmission characteristics are damaged. When the torsion temperature is less than 760℃, the glass rod does not reach the softening temperature, internal stress concentration occurs during twisting, the mechanical strength decreases, and the optical fiber may even break. The torsion angle is 180°(±1°). When the torsion angle is insufficient (e.g., less than 179°), complete image flipping cannot be achieved, which causes the observed image to have a directional deviation. When the torsion angle is too large (e.g., greater than 181°), the inverter defects increase, which affects the imaging quality. The torsion time is 60-110 minutes. When the torsion time is greater than 110 minutes, the glass excessively creeps at high temperature, which may cause the fiber structure to twist and deform, and the core diameter to be uneven. When the torsion time is less than 60 minutes, the glass softens and deforms insufficiently, the internal stress cannot be completely released, residual stress accumulates, and the optical fiber may be damaged. Finally, an optical fiber inverter blank is obtained.

[0067] The end surface of the optical fiber inverter blank is ground and polished. The grinder grinds for 1.5-2.5 h, and the polisher polishes for 2-4 h. After detection, an optical fiber inverter is obtained. When the grinding time is greater than 2.5 h, the end surface of the melt fiber rod is excessively removed, which may damage the size accuracy of the fiber rod and introduce deep scratches. When the grinding time is less than 1.5 h, the surface defects cannot be effectively eliminated, which affects the subsequent polishing effect. Similarly, when the polishing time is greater than 4 h, local overheating or excessive material loss may occur, which causes uneven surface morphology. When the polishing time is less than 2 h, it is difficult to completely remove the grinding marks, which affects the surface finish and optical performance.

[0068] The above molten fiber rod is subjected to high-temperature stretching process, a high-precision controllable temperature stretcher is used, the stretching temperature is 725-760 °C, if the stretching temperature exceeds 760 °C, the optical fiber taper is too soft, the stretching speed is accelerated, and the forming precision is affected; when the stretching temperature is lower than 725 °C, the glass does not reach softening, and in severe cases, the fiber rod cannot be stretched and formed, reducing the yield and production efficiency. The stretching time is 40-140 minutes, greater than 140 minutes, the stretching time is too long, which will cause the glass to be over-softened at high temperature, which may cause the fiber structure of the taper area to be distorted; less than 40 minutes, the stretching time is too short, which will cause stress concentration in the taper transition area, and structural defects are easy to occur. Then it is cut into two parts, and an optical fiber taper blank can be obtained.

[0069] The end face of the optical fiber taper blank is ground and polished, the grinder grinds for 1.5-2.5h, and the polisher polishes for 2-4h, wherein, greater than 2.5h, the grinding time is too long, which will cause the end face of the molten fiber rod to be excessively removed, which may damage the size accuracy of the fiber rod and introduce deep scratches; less than 1.5h, the grinding time is too short, which cannot effectively eliminate surface defects, affecting the subsequent polishing effect. Similarly, greater than 4h, the polishing time is too long, which may cause local overheating or excessive material loss, resulting in uneven surface topography; less than 2h, the polishing time is too short, which is difficult to completely remove the grinding marks, affecting the surface finish and optical performance, and the optical fiber taper is obtained after performance detection.

[0070] II. Ion beam etching process

[0071] (1) Use an ultrasonic cleaner to clean the optical fiber image element with deionized water, control the cleaning time to be 10-20 minutes, and then dry the optical fiber image element in a dry environment.

[0072] (2) Turn on the vacuum system of the ion beam etching machine, and vacuum the etching chamber to a suitable basic vacuum degree (usually about 10 -4 -10 -6 Pa) to reduce the interference of gas impurities on the etching process, wherein, less than 10 -6 Pa, the residual gas molecules will collide with the ion beam, not only scattering the ion trajectory to cause the etching precision to decrease, but also possibly introducing oxygen, carbon and other impurities to contaminate the etching surface, causing the roughness to increase or the chemical composition to change; greater than 10 -4 Pa, although the high vacuum degree can reduce the interference of impurities, it will greatly increase the vacuum time and equipment energy consumption.

[0073] (3) Carefully place the cleaned optical fiber on the sample table of the etching machine, use the sample clamp to fix the optical fiber firmly, and ensure that the optical fiber does not move during the etching process.

[0074] (4) Based on the principle of glow power generation, inert gas argon is ionized and decomposed into argon ions. The ion source is a microwave cyclotron resonance ion source, the ion beam energy is 250-600eV, the Ar flow rate is 8-35sccm, the direct current voltage is 700-1100V, and the etching angle is 0°. When the ion beam energy is greater than 600eV, the ion beam energy is too high, which may cause the etching rate to be too fast, causing surface sputtering, increasing roughness or damaging the underlying material. When the ion beam energy is less than 250eV, the energy is too low, which leads to a decrease in etching rate, making it difficult to effectively remove the material, and may cause anisotropy, weakening the etching ability. When the Ar flow rate is greater than 35sccm, the gas density increases, which will scatter the ion beam and reduce the etching uniformity. When the Ar flow rate is less than 8sccm, the ionization is insufficient, which leads to unstable plasma, fluctuating etching rate, and even causes local non-etching area. When the voltage is greater than 1100V, the set voltage is too high, which will accelerate the ion kinetic energy and may penetrate the surface of the material, causing non-selective etching or thermal damage. When the voltage is less than 700V, the ion beam focusing is poor, and the etching directionality is weakened.

[0075] (5) The argon ions are accelerated by the electric field and bombard the atoms on the surface of the fiber image element, causing the atoms of the skin layer glass 3b material to sputter out. The sputtering time is 4-10 minutes. When the sputtering time is less than 4 minutes, the sputtering time is too short, which will cause insufficient material removal, and it is difficult to effectively eliminate surface defects or achieve the target etching depth. When the sputtering time is greater than 10 minutes, the sputtering time is too long, which may cause excessive etching, leading to uneven loss of skin layer glass 3b material and surface roughness.

[0076] (6) After the skin layer glass etching is completed, first, the ion beam power is turned off to stop the ion beam bombardment. Then, the argon gas valve is closed to stop the gas supply.

[0077] (7) After the vacuum degree in the etching chamber returns to an appropriate level, the etched fiber image element is carefully taken out. The fiber image element is placed in ionized water for ultrasonic cleaning to remove sputtering residue, reaction products and other impurities generated during the etching process. After cleaning, the oven is used for drying.

[0078] As Figure 2 shown is the input end face groove structure of the fiber image element of the present application, based on the hardness difference between the core glass 2b and the skin layer glass 3b, ion etching can be performed to process the groove structure. Due to the composition diffusion phenomenon of the glass fiber at the interface between the core glass 2b and the cladding glass 3b, the input end face of the fiber image element is a gradually recessed structure, and the fluorescent powder 1b is tightly attached to the surface of the fiber input end. The G100M laser interferometer is used to test the surface testing accuracy of the etched recessed structure, and the 6JA interference microscope is used to test the roughness of the etched recessed structure.

[0079] Some embodiments of the present application also provide a micro-concave structure fiber image guide element, which has an input end surface for receiving and transmitting incident light and an opposite output end surface, the input end surface having a concave structure; the concave structure has an etching depth of 3.05-3.3 mm, a surface accuracy of 0.34-0.46 lambda, and a roughness of 2.12-2.21 nm; the fiber array is gradually concave from the edge to the center of the fiber image guide element. The edge fiber is nearly planar, and the concave degree increases towards the center, forming a smooth concave surface as a whole. The etching depth of the above concave structure refers to the "depth of the concave at the center position of the fiber on the input end surface of the fiber image guide element".

[0080] Some embodiments of the present application also provide an optical system comprising the above micro-concave structure fiber image guide element. The optical system can be a low-light night vision device or a high-energy detector. In the low-light night vision device, the element significantly improves the imaging clarity and contrast in low-light environments through efficient image transmission and light signal enhancement capability, and is suitable for military reconnaissance, security monitoring, and night navigation, etc. In the high-energy detector (such as X-ray or particle detector), its precise micro-concave structure can optimize the light energy collection efficiency and radiation resistance performance, and serve the fields of nuclear physics experiments, medical imaging equipment, or space exploration instruments, etc.

[0081] The present application is further described below in conjunction with specific embodiments.

[0082] Embodiment 1: Fiber panel (its input end is a concave structure)

[0083] Preparation of core glass rod and cladding glass tube:

[0084] (1) According to the mass ratio in Table 2, weigh the silicon dioxide, boron oxide, zinc oxide, calcium oxide, lithium oxide, titanium oxide, lanthanum oxide and bismuth oxide powders, mix them uniformly, and then put them into a platinum crucible, heat to 1550℃, and make each component completely melt, keep the temperature for 7 hours, and continuously stir slowly at a speed of 8.5 rpm during the process to ensure uniform fusion of each component. Then, the molten glass liquid flows out through the discharge port and is formed into a glass rod with a diameter of 30 mm. After being kept at 650℃ for 2 hours, the power is turned off and it is naturally cooled to room temperature to complete the annealing process, and finally the core glass rod is obtained.

[0085] (2) Weigh out the powders of silicon dioxide, aluminum oxide, calcium oxide, sodium oxide, and potassium oxide according to the mass ratio in Table 3. Mix them thoroughly using a mixer and place them in a platinum crucible. Heat the mixture to 1500℃ and maintain it for 6 hours, with the stirring paddle rotating at 11 rpm to ensure thorough mixing. After heating to 1500℃, use a robotic arm to draw the molten glass into a glass tube that matches the mandrel, with an inner diameter of 31 mm. Place the glass tube in an annealing furnace and heat it to 580℃. Hold it at that temperature for 3 hours and then allow it to cool naturally to room temperature to complete the annealing process, finally obtaining a skin glass tube. The wall thickness of the skin glass tube is 4.5 mm, and the outer diameter is 35.5 mm.

[0086] (3) Subsequently, the core glass rod and the corrugated glass tube were made into samples with a length of 50 mm, a width of 50 mm, and a height of 10 mm, respectively. Their hardness was measured using an HV-100 Vickers hardness tester, as shown in Table 4. The hardness of the core glass rod was 5.21 GPa, and the hardness of the corrugated glass 3b was 6.48 GPa.

[0087] 2. Fabrication of fiber optic panels:

[0088] (1) After matching the core glass rod and the corrugated glass tube, a single filament was drawn at 810℃ for 45 minutes to obtain a 2.5μm single filament; the light-absorbing glass rod was drawn into a 0.35μm light-absorbing filament at 820℃ for 60 minutes. The corrugated glass tube with a refractive index of 1.48 at a wavelength of 594nm was drawn into a structural filament at 810℃ for 75 minutes to obtain a 0.35μm structural filament.

[0089] (2) Preparation of primary multifilament: The single filaments drawn in step (1) are arranged into a hexagon with a regular hexagonal cross-section. Structural wires and light-absorbing wires are inserted into the gaps between the single filaments in the optical fiber. The fiber is then bound with cotton thread and copper wire at both ends. The fiber is then clamped on a drawing machine and drawn at 780°C for 65 minutes to form a primary multifilament with a side dimension of 1.03 μm and a regular hexagonal cross-section.

[0090] (3) Preparation of secondary multifilament: The primary multifilament obtained in step (2) is arranged in a regular hexagonal structure, and then tied with cotton thread. Both ends are tied with non-flammable copper wire. Then, it is clamped on a drawing machine and drawn at 800°C for 70 minutes to form a secondary multifilament with a side dimension of 0.79μm and a cross-section of regular hexagon.

[0091] (4) The secondary multifilaments obtained in step (3) are arranged in a hexagonal close-packed manner and then bound together with copper wire to form a composite fiber bundle. The composite fiber bundle is then cut into 90mm pieces with a side dimension of 40mm.

[0092] (5) Hot melt compression molding: the composite optical fiber bundle obtained in step (4) is placed into a hot melt compression molding mold, the mold loaded with the composite optical fiber bundle is placed into a hot melt compression molding furnace at a high temperature of 520°C, a pressure of 70N is applied to the six directions of the composite optical fiber bundle to start the pressing plate, and a time control of 130 minutes can obtain a fused fiber rod.

[0093] (6) After the fused fiber rod is rounded, cutting, grinding and polishing are performed, wherein the fused fiber rod is cut into a length of 20mm using a cutting machine, the grinding machine grinds for 1.5h, and the polishing machine polishes for 2h, and an optical fiber panel can be obtained.

[0094] 3. Ion beam etching

[0095] (1) The optical fiber image transmission element is cleaned using an ultrasonic cleaner with deionized water for 13 minutes, and then the optical fiber image transmission element is placed in a drying oven with a drying temperature of 50°C for 30 minutes.

[0096] (2) The vacuum system of the ion beam etching machine is turned on, and the etching chamber is pumped to a pressure of 10 -5 Pa to reduce the interference of gas impurities on the etching process.

[0097] (3) The cleaned optical fiber image transmission element is placed on the sample stage of the etching machine, and the optical fiber is fixed firmly using a sample clamp to ensure that the optical fiber does not move during etching.

[0098] (4) Based on the principle of glow discharge, the inert gas is set to argon with a purity of 99.999%, and the argon is ionized and decomposed into argon ions. The ion source is a microwave cyclotron resonance ion source, the ion beam energy is 400eV, the Ar flow rate is 20sccm, the direct current voltage is 900V, and the etching angle is 0°.

[0099] (5) The argon ions are accelerated by the electric field and bombard the atoms on the surface of the optical fiber image transmission element, causing the atoms of the skin layer glass 3b material to sputter, and the sputtering time is 6 minutes.

[0100] (6) When the skin layer glass etching is completed, the ion beam power is turned off to stop the ion beam bombardment. Then the argon valve is closed to stop the gas supply.

[0101] (7) Wait for the vacuum degree in the etching chamber to recover to 1.33×10 -4After the etching, the etched fiber image transfer element was taken out and put into ionized water for ultrasonic cleaning for 20 minutes at a temperature of 65°C to remove the sputtering residues, reaction products and other impurities generated during the etching process. After cleaning, the etched fiber image transfer element was again put into a drying oven at a temperature of 50°C for 35 minutes to obtain a fiber panel, and the output end face of the fiber panel was the etched groove structure with an etching depth of 3.21 μm.

[0102] Example 2-5: Fiber panel (with a groove structure at the input end)

[0103] Example 2-5 differs from Example 1 in that the composition and proportion of the core glass and the cladding glass are different, and the remaining preparation steps and parameters are the same as those of Example 1.

[0104] Table 2. Composition and mass ratio (wt.%) of the core glass of Examples 1-5

[0105] Composition Example 1 Example 2 Example 3 Example 4 Example 5 Silicon dioxide 34.3 36.5 36.8 37.2 37.4 Boron oxide 25 24.3 23.9 23.5 22.9 Zinc oxide 6.2 10.2 8.7 6.5 5.5 Lanthanum oxide 12 12 12.3 12.7 13 Lithium oxide 3.3 2 2.4 2.8 3.1 Bismuth oxide 7.4 6 6.4 6.8 7.1 Titanium oxide 6.5 5 5.2 5.7 5.9 Calcium oxide 5.3 4 4.3 4.8 5.1

[0106] Table 3. Composition and mass ratio (wt.%) of the cladding glass of Examples 1-5

[0107]

[0108]

[0109] Table 4. Related properties of the fiber panel of Examples 1-5

[0110]

[0111] Table 5. Related properties of the fiber panel (with a groove structure at the input end) of Examples 1-5

[0112]

[0113] Figure 2The input end face groove structure of the optical fiber image transmission element is shown, and the groove structure is machined based on the hardness difference between the core glass 2b and the cladding glass 3b through ion etching. Due to the composition diffusion phenomenon of the glass fiber at the interface between the core glass and the cladding glass, the input end face of the optical fiber image transmission element is a gradually recessed structure, that is, the input end face of the optical fiber panel with the etched groove structure is obtained, and the groove structure is tested by a zygo high-precision white light interferometer. The fluorescent powder 2b is tightly attached to the surface of the input end of the optical fiber. The surface profile accuracy of the etched groove structure is tested by using a G100M laser interferometer, and the roughness of the etched groove structure is tested by using a 6JA interference microscope. The etching depth, surface profile accuracy and roughness obtained by testing in the above examples 1-5 are summarized in table 5. As can be seen from table 5, with the increase of the hardness of the core glass 2b and the cladding glass 3b, the etching depth of the groove structure of the input end face of the optical fiber panel in examples 1-5 gradually decreases, and at the same time, the surface profile accuracy and the surface roughness of the groove structure also change.

[0114] Example 6: optical fiber inverter (the input end thereof is a groove structure)

[0115] 1. Preparation of core glass and cladding glass tubes

[0116] The preparation steps and parameters are the same as those in example 1.

[0117] 2. Preparation of optical fiber inverter:

[0118] The pre-preparation process of the optical fiber panel blank in steps (1)-(6) is the same as the preparation process of the optical fiber panel in example 1, and the optical fiber panel blank can be obtained.

[0119] (7) The above optical fiber panel blank is subjected to a high-temperature torsion process, and is twisted by a high-precision twisting machine. The temperature of the high-temperature torsion is set to 780℃, the twisting angle is 180°, and the twisting time is 45 minutes. An optical fiber inverter blank is obtained.

[0120] (8) The end face of the optical fiber inverter blank is ground and polished. The grinding machine is ground for 1.5h, and the polishing machine is polished for 2h.

[0121] 3. Ion beam etching

[0122] The etching process flow of the optical fiber inverter is the same as the etching process of the optical fiber panel in example 1, and the sputtering time is 6 minutes. Finally, an optical fiber inverter with an etched groove structure at the input end face is obtained. The etching depth of the groove structure is 3.19μm, the surface profile accuracy of the etched groove structure is 0.35λ tested by using a G100M laser interferometer, and the roughness of the etched groove structure is 2.31nm tested by using a 6JA interference microscope. The etching depth, surface profile accuracy and roughness of the input end face of the optical fiber inverter obtained by testing are summarized in table 6.

[0123] Example 7: Fiber optic taper (the input end of which is a groove structure)

[0124] 1. Preparation of core glass and cladding glass tubes

[0125] The preparation steps and parameters are the same as in Example 1.

[0126] 2. Preparation of a fiber optic taper:

[0127] (1) - (6) The preliminary preparation process of the fiber optic panel blank is the same as the preparation process of the fiber optic panel in Example 1, and the fiber optic panel blank can be obtained.

[0128] (7) The fiber optic panel blank is subjected to a high-temperature stretching process, using a high-precision temperature-controllable stretcher, the stretching temperature is 730°C, the stretching time is 45 minutes, and the stretching taper ratio is 2.5:1. After cutting it in half, a fiber optic taper blank can be obtained.

[0129] (8) The end face of the fiber optic taper blank is ground and polished, the grinder grinds for 1.5h, and the polisher polishes for 2h.

[0130] 3. Ion beam etching

[0131] The etching process flow of the fiber optic taper is the same as the etching process of the fiber optic panel in Example 1. For a fiber optic taper with a taper ratio of 2.5:1, the sputtering time is 6 minutes. Finally, a fiber optic taper with an input end face of an etched groove structure is obtained. The etching depth of the groove structure is 3.21 μm. The surface accuracy of the etched groove structure is 0.41λ using a G100M laser interferometer, and the roughness of the etched groove structure is 2.25 nm using a 6JA interference microscope. The etching depth, surface accuracy, and roughness of the input end face of the fiber optic taper obtained by testing are summarized in Table 6.

[0132] Example 8: Fiber optic panel (the input end of which is a groove structure)

[0133] 1. Preparation of core glass and cladding glass tubes

[0134] The preparation steps and parameters are the same as in Example 1.

[0135] 2. Preparation of a fiber optic panel

[0136] The preparation steps and parameters are the same as in Example 1.

[0137] 3. Ion beam etching

[0138] The etching process of the fiber faceplate is the same as that in Example 1, wherein the ion beam energy is 450 eV, the Ar flow rate is 20 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 6 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 3.23 μm, the surface accuracy of the groove structure after etching is 0.42λ as tested by a G100M laser interferometer, and the roughness of the groove structure after etching is 2.2 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0139] Example 9: Fiber faceplate (the input end of which is a groove structure)

[0140] 1. Preparation of core glass and cladding glass tubes

[0141] The preparation steps and parameters are the same as those in Example 1.

[0142] 2. Preparation of fiber faceplate

[0143] The preparation steps and parameters are the same as those in Example 1.

[0144] 3. Ion beam etching

[0145] The etching process of the fiber faceplate is the same as that in Example 1, wherein the ion beam energy is 450 eV, the Ar flow rate is 20 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 6 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 3.23 μm, the surface accuracy of the groove structure after etching is 0.42λ as tested by a G100M laser interferometer, and the roughness of the groove structure after etching is 2.2 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0146] Comparative Example 1: Fiber faceplate (the input end of which is a groove structure)

[0147] 1. Preparation of core glass and cladding glass tubes

[0148] The preparation steps and parameters are the same as those in Example 1.

[0149] 2. Preparation of fiber faceplate

[0150] The preparation steps and parameters are the same as those in Example 1.

[0151] 3. Ion beam etching

[0152] The etching process of the fiber faceplate is the same as that of Example 1, wherein the ion beam energy is 200 eV, the Ar flow rate is 20 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 6 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 2 μm, the surface accuracy of the groove structure after etching is 0.1 λ as tested by a G100M laser interferometer, and the roughness of the groove structure after etching is 5.5 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0153] Example 10: Fiber faceplate (the input end of which is a groove structure)

[0154] The etching process of the fiber faceplate is the same as that of Example 1, wherein the ion beam energy is 400 eV, the Ar flow rate is 25 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 6 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 3.24 μm, the surface accuracy of the groove structure after etching is 0.43 λ as tested by a G100M laser interferometer, and the roughness of the groove structure after etching is 2.19 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0155] Example 11: Fiber faceplate (the input end of which is a groove structure)

[0156] 1. Preparation of core glass and cladding glass tubes

[0157] The preparation steps and parameters are the same as those of Example 1.

[0158] 2. Preparation of fiber faceplate

[0159] The preparation steps and parameters are the same as those of Example 1.

[0160] 3. Ion beam etching

[0161] The etching process of the fiber faceplate is the same as that of Example 1, wherein the ion beam energy is 400 eV, the Ar flow rate is 30 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 6 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 3.26 μm, the surface accuracy of the groove structure after etching is 0.46 λ as tested by a G100M laser interferometer, and the roughness of the groove structure after etching is 2.17 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0162] Comparative Example 2: Fiber faceplate (input end is a groove structure)

[0163] 1. Preparation of core glass and cladding glass tubes

[0164] The preparation steps and parameters are the same as in Example 1.

[0165] 2. Preparation of fiber faceplate

[0166] The preparation steps and parameters are the same as in Example 1.

[0167] 3. Ion beam etching

[0168] The etching process flow of the fiber faceplate is the same as in Example 1, except that the ion beam energy is 400 eV, the Ar flow rate is 10 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 6 minutes, and finally a fiber faceplate is obtained, the input end surface of which is an etched groove structure. The etching depth of the groove structure is 1.7 μm, the surface accuracy of the etched groove structure is 0.15λ as tested by a G100M laser interferometer, and the roughness of the etched groove structure is 6.3 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy, and roughness of the input end surface of the fiber faceplate obtained by testing are summarized in Table 6.

[0169] Example 12: Fiber faceplate (input end is a groove structure)

[0170] The etching process flow of the fiber faceplate is the same as in Example 1, except that the ion beam energy is 400 eV, the Ar flow rate is 20 seem, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 7 minutes, and finally a fiber faceplate is obtained, the input end surface of which is an etched groove structure. The etching depth of the groove structure is 3.25 μm, the surface accuracy of the etched groove structure is 0.43λ as tested by a G100M laser interferometer, and the roughness of the etched groove structure is 2.18 nm as tested by a 6JA interference microscope. The etching depth, surface accuracy, and roughness of the input end surface of the fiber faceplate obtained by testing are summarized in Table 6.

[0171] Example 13: Fiber faceplate (input end is a groove structure)

[0172] 1. Preparation of core glass and cladding glass tubes

[0173] The preparation steps and parameters are the same as in Example 1.

[0174] 2. Preparation of fiber faceplate

[0175] The preparation steps and parameters are the same as in Example 1.

[0176] 3. Ion beam etching

[0177] The etching process of the fiber faceplate is the same as that of Example 1, wherein the ion beam energy is 400 eV, the Ar flow rate is 20 sccm, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 8 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 3.3 μm, the surface accuracy of the groove structure after etching is 0.45λ tested by using a G100M laser interferometer, and the roughness of the groove structure after etching is 2.16 nm tested by using a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0178] Comparative Example 3: Fiber faceplate (the input end of which is a groove structure)

[0179] The etching process of the fiber faceplate is the same as that of Example 1, wherein the ion beam energy is 400 eV, the Ar flow rate is 20 sccm, the direct current voltage is 900 V, and the etching angle is 0°. The sputtering time is 3 minutes, and finally a fiber faceplate is obtained, the input end face of which is a groove structure after etching. The etching depth of the groove structure is 2.5 μm, the surface accuracy of the groove structure after etching is 0.2λ tested by using a G100M laser interferometer, and the roughness of the groove structure after etching is 5.8 nm tested by using a 6JA interference microscope. The etching depth, surface accuracy and roughness of the input end face of the fiber faceplate obtained by testing are summarized in Table 6.

[0180] According to the test data in Table 6, it is shown that the process parameters such as ion beam energy, Ar gas flow rate and sputtering time have a significant influence on the etching characteristics of the fiber faceplate. In the ion beam energy gradient study (Examples 8, 9 and 1), as the energy increases from 400 eV to 500 eV, the etching depth increases from 3.21 μm to 3.28 μm, the surface accuracy increases from 0.41λ to 0.45λ, and the surface roughness decreases from 2.21 nm to 2.18 nm. This phenomenon can be attributed to the fact that the increase of the ion beam energy significantly increases the kinetic energy of the incident ions, thereby increasing the sputtering yield and improving the uniformity of the surface morphology. In Comparative Example 1, when the energy is reduced to 200 eV, the sputtering yield is sharply reduced due to the insufficient ion bombardment intensity, the etching depth is only 2.0 μm, the surface accuracy is reduced to 0.1λ, and the roughness is increased to 5.5 nm, which fully verifies the key role of the energy threshold effect on the etching quality. In the Ar flow rate variable study (Examples 10, 11 and 1), as the flow rate increases from 20 sccm to 30 sccm, the etching depth increases from 3.21 μm to 3.26 μm, the surface accuracy increases from 0.41λ to 0.46λ, and the roughness decreases from 2.21 nm to 2.17 nm, which is mainly due to the fact that the increase of the Ar flow rate increases the sputtering yield and improves the uniformity of the surface morphology. In the sputtering time variable study (Examples 12, 13 and 1), as the sputtering time increases from 3 minutes to 8 minutes, the etching depth increases from 2.5 μm to 3.3 μm, the surface accuracy increases from 0.2λ to 0.45λ, and the roughness decreases from 5.8 nm to 2.16 nm, which is mainly due to the fact that the increase of the sputtering time increases the sputtering yield and improves the uniformity of the surface morphology. +The increase of ion density promotes more uniform plasma distribution and more efficient sputtering process; while the comparative example 2, under the condition of low flow rate of 10 sccm, the sputtering is not uniform due to insufficient plasma density, the etching depth is only 1.7 μm, the surface accuracy is reduced to 0.15 λ, and the roughness is increased to 6.3 nm. In the sputtering time parameter study (Examples 12, 13 and 1), when the time is extended from 6 min to 8 min, the etching depth is increased from 3.21 μm to 3.30 μm, the surface accuracy is increased from 0.41 λ to 0.45 λ, and the roughness is reduced from 2.21 nm to 2.16 nm, which is due to the longer sputtering time that enables the complete removal of the surface atomic layer; while the comparative example 3 with short time of 3 min fails to complete the surface reconstruction process, resulting in sub-optimal results of etching depth of only 2.5 μm, surface accuracy of 0.2 λ, and roughness of 5.8 nm. It is worth noting that the parameter settings of all examples are strictly controlled within the process parameters, while the comparative examples intentionally set the parameters below the threshold value to systematically verify the lower limit critical value of each process parameter, which provides an important basis for optimizing the ion beam etching process.

[0181] Table 6 Related performance of optical fiber image elements (with groove structure at the input end) of Examples 6-13 and Comparative Examples 1-3

[0182]

[0183]

[0184] In the above examples, the description of each example focuses on different aspects, and the parts not described in detail in a certain example can be referred to the related description of other examples.

[0185] The microstructure described in the present application, any simple deposition film layer on the surface of the microstructure for modifying, protecting or passivating the surface of the microstructure, should be within the protection scope of the present application.

[0186] The numerical range described in the present application includes all numerical values within the range, and includes the range value composed of any two numerical values within the range. Different numerical values of the same index appearing in all examples of the present application can be combined to form a range value.

[0187] The technical features in the claims and / or description of the present application can be combined, and the combination manner is not limited to the combination obtained by reference relationship in the claims. The technical solution obtained by combining the technical features in the claims and / or description is also within the protection scope of the present application.

[0188] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method of fabricating a micro-recessed structure fiber-optic image-conveying element, characterized by: It comprises the following steps: S1. The core glass rod and the skin glass tube are matched and drawn into a primary monofilament; The black absorbing glass rod is drawn into a light absorbing glass gap filament; The skin glass rod is drawn into a skin glass gap filament; The core glass rod comprises the following components in percentage by mass: SiO2 34-46%; B2O3 16-25%; ZnO 5-11%; La2O3 12-17%; Li2O 2-5%; Bi2O3 5-10%; TiO2 5-18%; CaO 4-15%; and the skin glass tube comprises the following components: SiO2 50-60%; Al2O3 0-3%; CaO 5-13%; B2O3 10-22%; K2O 18-30%; Na2O 3-15%; S2. The primary monofilament is arranged in a hexagonal closest packing, the light absorbing glass gap filament and the skin glass gap filament are sequentially inserted into the gap of the primary monofilament to obtain a primary composite rod, and the primary composite rod is drawn into a primary multifilament; S3. The primary multifilament is arranged in a hexagonal closest packing to form a secondary composite rod, and is drawn into a secondary multifilament; S4. The secondary multifilament is arranged in a hexagonal closest packing, and is cut to a fixed length to form a plate segment of 70-110 mm, and the plate segment is formed into a fused fiber rod by hot melting and compression molding; S5. The fused fiber rod is processed into an optical fiber image transmission element by post-processing; S6. The obtained optical fiber image transmission element is subjected to ion beam etching under vacuum conditions, and the micro-concave structure optical fiber image transmission element is obtained. In step S1, the drawing temperature of the primary monofilament is 790-850℃, and the time is 30-120 minutes; the drawing temperature of the light absorbing glass gap filament is 820℃-860℃, and the time is 30-100 minutes; the drawing temperature of the skin glass gap filament is 750℃-800℃, and the time is 45-120 minutes; the diameter of the primary monofilament is 2-4 mm; the diameter of the light absorbing glass gap filament is 0.3-0.5 mm; and the diameter of the skin glass gap filament is 0.3-0.5 mm.

2. The method for fabricating a micro-concave optical fiber imaging element as described in claim 1, characterized in that, In step S2, the drawing temperature is 760℃-840℃, and the time is 35-130 minutes; the opposite side size of the primary multifilament is 1.00-1.08 mm; in step S3, the drawing temperature is 760℃-830℃, and the time is 50-160 minutes; the opposite side size of the secondary multifilament is 0.78-0.85 mm; in step S4, the cutting size of the plate segment is 70-110 mm; the temperature of the hot melting and compression molding is 500℃-550℃, the time is 120-210 min, and the pressure is 45-100 N.

3. The method for fabricating a micro-concave optical fiber imaging element as described in claim 1, characterized in that, In step S5, the post-processing comprises the following steps:

4. The method for fabricating a micro-concave optical fiber imaging element as described in claim 1, characterized in that, The fused fiber rod is rounded, and is subjected to cutting, grinding and polishing to obtain an optical fiber panel. In step S5, the cutting length of the fused fiber rod is 17-35 mm, the grinding time is 1.5-2.5 h, and the polishing time is 2-4 h.

5. The method for fabricating a micro-concave optical fiber imaging element as described in claim 4, characterized in that, In step S5, the post-processing comprises the following steps:

6. The method for fabricating a micro-concave optical fiber imaging element as described in claim 1, characterized in that, a1. The fused fiber rod is twisted to obtain an optical fiber inverter blank; ​ b1 grinding and polishing the end face of the fiber inverter blank, grinding for 1.5-2.5h and polishing for 2-4h, and obtaining the fiber inverter after detection.

7. The method for fabricating a micro-concave optical fiber imaging element as described in claim 6, characterized in that, In step a1, the twisting temperature is 760-800℃, the twisting angle is 179°-181°, and the twisting time is 60-110 minutes; in step b1, the grinding time is 1.5-2.5h, and the polishing time is 2-4h.

8. The method for fabricating a micro-concave optical fiber imaging element as described in claim 1, characterized in that, In step S5, the post-treatment comprises the following steps: a2 stretching the molten fiber rod, cutting it and then dividing it into two, and obtaining a fiber taper blank; b2 grinding and polishing the end face of the fiber taper blank, grinding for 1.5-2.5h and polishing for 2-4h, and obtaining the fiber taper after performance detection.

9. The method for fabricating a micro-concave optical fiber imaging element as described in claim 8, characterized in that, In step a2, the stretching temperature is 725-760℃, the stretching time is 40-140 minutes, and the stretching taper ratio is 2.5:1; in step b2, the grinding time is 1.5-2.5h, and the polishing time is 2-4h.

10. The method for fabricating a micro-concave optical fiber imaging element as described in claim 1, characterized in that, In step S6, the operation parameters of the ion beam etching are set as follows: vacuum degree is 10 -4 -10 -6 Pa, ion beam energy is 250-600 eV, Ar flow rate is 8-35 sccm, direct current voltage is 700-1100 V, and etching angle is 0°.

11. A micro-recessed structured fiber-optic imaging device prepared by the method of any one of claims 1-10, wherein, The micro-concave structure fiber image transmission element has an input end face for receiving and transmitting incident light and an opposite output end face, and the input end face has a groove structure; the etching depth of the groove structure is 3.05-3.3mm, the surface accuracy is 0.34-0.46λ, and the roughness is 2.12-2.21nm.

12. An optical system characterized by, The optical system comprises the micro-concave structure fiber image transmission element of claim 11.

Images