A quartz window for enhancing solar-blind ultraviolet detection, its preparation method and application

Abstract

This invention relates to a quartz optical window for enhancing solar-blind ultraviolet detection, its fabrication method, and its application. The method includes: etching a periodic array of hollow micro / nano structures with gradually changing morphology on the emitting end face of a quartz substrate with high transmittance in the solar-blind ultraviolet band; cleaning to obtain a quartz element; depositing a solar-blind ultraviolet-transmittance thin film material as the filling material for the hollow structure on the emitting end face of the obtained quartz element; polishing the coated emitting end face to obtain a functional layer of a periodic array of micro / nano structures with a period of 100nm–300nm, a thickness of 80nm–300nm, and a duty cycle greater than or equal to 0.5; cleaning to obtain a quartz optical window for enhancing solar-blind ultraviolet detection with the periodic array of micro / nano structures. This invention improves the quantum efficiency of the cesium telluride photocathode in a solar-blind ultraviolet image intensifier by using a quartz optical window with a micro / nano structure functional layer, thereby improving the cathode sensitivity and achieving long-distance, high-definition detection.

Description

Technical Field

[0001] This invention belongs to the field of optical element and micro / nano structure manufacturing technology, specifically relating to a quartz optical window for enhancing solar-blind ultraviolet detection, its preparation method, and its application. Background Technology

[0002] Because the ozone layer in the atmosphere strongly absorbs ultraviolet radiation, the mid-ultraviolet radiation in the 200nm–280nm range of solar radiation reaching the Earth's surface is extremely weak; this band is known as the "solar spectral blind zone" or "solar blindness." Since there is almost no solar radiation in the solar blind band in the near-Earth atmosphere, and there is no interference from solar background radiation, it is highly advantageous for capturing external signals in this band. Because a large amount of solar blind ultraviolet radiation is generated by the exhaust plumes of aircraft and missiles, corona and arc discharges, and forest fires, solar blind ultraviolet detection imaging technology has been widely researched and applied in many key fields such as military defense, aerospace, corona detection, fire early warning, and ultraviolet optical communication.

[0003] Currently, solar-blind ultraviolet (UV) detection imaging technologies mainly include image-intensity charge-coupled devices (ICCDs) and solid-state area array sensors. Solid-state area array sensors, due to issues such as short detection distance, unstable manufacturing processes, and low resolution, are still in the research and development stage and cannot yet be applied. Solar-blind UV ICCD technology, on the other hand, has already been applied in military and industrial fields due to the advantages of low dark current, fast response speed, good stability, low false alarm rate, and mature manufacturing processes of solar-blind UV image intensifiers. However, the low quantum efficiency of the cesium telluride photocathode in solar-blind UV image intensifiers leads to low cathode sensitivity, resulting in a short detection distance, which severely limits its application and development. To compensate for the low quantum efficiency of solar-blind ultraviolet photocathodes, common techniques include: (1) optimizing the fabrication process of cesium telluride photocathodes to increase the photoelectron emission rate of the cesium telluride photocathode layer; (2) innovating MCP materials and processes to increase the multiplication rate of photoelectrons generated in microchannels; and (3) innovating fluorescent screen materials and processes to improve the imaging brightness and clarity of electron bombardment of the fluorescent screen. Although current techniques help to increase the detection distance, the improvement effect is not significant and still cannot meet the needs of high-performance solar-blind ultraviolet detection. Summary of the Invention

[0004] In view of this, the main objective of the present invention is to provide a quartz optical window for enhancing solar-blind ultraviolet detection, its preparation method and application. The technical problem to be solved is to improve the quantum efficiency of the cesium telluride photocathode in a solar-blind ultraviolet image intensifier by using a quartz optical window with a micro-nano structure functional layer, thereby improving the cathode sensitivity and achieving the purpose of long-distance, high-definition detection.

[0005] The objective of this invention and the technical problem it solves are achieved through the following technical solution. This invention proposes a method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, comprising the following steps:

[0006] 1) A periodic array of hollow micro-nano structures with gradually changing morphology is etched on the exit end face of a clean quartz substrate with high transmittance in the solar blind ultraviolet band. After multiple ultrasonic cleanings, a clean quartz element with a periodic array of hollow micro-nano structures with neat edges is obtained.

[0007] 2) A thin film material with high solar blind ultraviolet transmittance is deposited on the emitting end surface of the quartz element obtained in step 1) as the filling material for the hollow structure;

[0008] 3) Polish the exit end face after coating in step 2) to obtain a periodic array micro-nano structure functional layer with an embedded solid morphology of 80nm to 300nm thickness. Then, ultrasonic cleaning is performed to obtain a quartz window for enhancing solar-blind ultraviolet detection with a periodic array of micro-nano structures.

[0009] Preferably, in the aforementioned method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, in step 1), the quartz substrate has a refractive index n = 1.5 at a wavelength of 250 nm and a transmittance ≥ 90% at a wavelength of 250 nm.

[0010] Preferably, in the aforementioned method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, in step 1), the hollow micro / nano structure periodic array is distributed in a hexagonal close-packed or tetragonal close-packed pattern.

[0011] Preferably, in the aforementioned method for preparing a quartz window for enhancing solar-blind ultraviolet detection, in step 1), the top of the morphology of the hollow micro / nano structure periodic array faces the interior of the quartz substrate.

[0012] Preferably, in the aforementioned method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, in step 1), the hollow micro / nano structure periodic array with gradually changing morphology includes multiple micro / nano structure units. The micro / nano structure units have a conical, frustum, Gaussian surface, or cylindrical shape. The bottom projection outline of the micro / nano structure unit is circular, square, or regular polygonal. The radius of the bottom projection circle / circumscribed circle is 50nm to 150nm, the radius of the top projection circle / circumscribed circle is less than or equal to 50nm, the period is 100nm to 300nm, the height / depth is 80nm to 300nm, and the duty cycle of the micro / nano structure periodic array is greater than or equal to 0.5.

[0013] Preferably, in the aforementioned method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, step 1) includes ultrasonic cleaning, conventional ultrasonic cleaning, alternating acid-base ultrasonic cleaning, and anhydrous ethanol / isopropanol ultrasonic cleaning.

[0014] Preferably, in the aforementioned method for preparing a quartz window for enhancing solar-blind ultraviolet detection, in step 2), the refractive index of the thin film material is greater than that of the transparent substrate, and it is transparent to ultraviolet light with a working wavelength of 200 nm to 280 nm.

[0015] Preferably, in the aforementioned method for preparing a quartz window for enhancing solar-blind ultraviolet detection, in step 2), the thin film material is selected from one thin film or a composite thin film of at least two of the following: magnesium oxide, hafnium oxide, aluminum oxide, and zirconium oxide.

[0016] The objectives of this invention and the technical problems it solves can be further achieved by the following technical measures. This invention proposes a quartz optical window for enhancing solar-blind ultraviolet detection. The quartz optical window includes a quartz substrate, which has an incident end face for receiving and transmitting incident light and an opposing exit end face. The exit end face of the quartz substrate has a periodic array of hollow micro / nano structures with gradually changing morphology. The periodic array of micro / nano structures includes multiple micro / nano structure units. The micro / nano structure units of the exit end face are filled with a transparent thin film material with a high refractive index, forming a solid periodic array of micro / nano structures.

[0017] Preferably, in the aforementioned quartz window for enhancing solar-blind ultraviolet detection, the hollow micro / nano structure periodic array has a conical, frustum, Gaussian surface, or cylindrical shape. Its bottom projection outline on the plane is circular, square, or regular polygonal. The radius of the bottom projection circle / circumscribed circle radius R is 50nm to 150nm, the radius of the top projection circle / circumscribed circle radius r ≤ 50nm, the period P is 100nm to 300nm, the height / depth H is 80nm to 300nm, and the duty cycle of the micro / nano structure periodic array is ≥ 0.5.

[0018] Preferably, in the aforementioned quartz optical window for enhancing solar-blind ultraviolet detection, the substrate is made of quartz optical quartz, which has a refractive index of 1.5 at a wavelength of 250 nm and a transmittance of ≥90% in the effective region of 200 nm to 280 nm; the refractive index of the transparent thin film material is greater than that of the quartz substrate, and it is transparent to ultraviolet light at the working wavelength of 200 nm to 280 nm.

[0019] The objectives of this invention and the solutions to its technical problems can be further achieved by the following technical measures. This invention proposes an optical device comprising a quartz window for enhancing solar-blind ultraviolet detection; the quartz window comprises a quartz substrate having an incident end face for receiving and transmitting incident light and an opposing exit end face; the exit end face of the quartz substrate has a periodic array of micro / nano structures with gradually changing morphology, the periodic array of micro / nano structures comprising multiple micro / nano structure units; the micro / nano structure units of the exit end face are filled with a transparent thin film material with a high refractive index to form a solid micro / nano structure periodic array.

[0020] Preferably, in the aforementioned optical device, the optical device is a solar-blind ultraviolet image intensifier.

[0021] By employing the above technical solution, the quartz optical window for enhancing solar-blind ultraviolet detection, its preparation method, and its application provided by the present invention have at least the following advantages:

[0022] The quartz optical window for enhancing solar-blind ultraviolet detection provided by this invention forms a high-refractive-index gradient micro-nano structure functional layer by constructing a periodic array of gradient micro-nano structures on the exit end face. This reduces interface reflection and scattering between the exit end face of the quartz optical window and the cesium telluride photocathode layer, thereby improving transmittance and diffraction efficiency. Ultimately, this achieves the goals of anti-reflection enhancement, stray light elimination, and improved quantum efficiency of the cesium telluride photocathode in the wavelength range of 200nm to 280nm.

[0023] The transmissive quartz optical element prepared by the method provided in this invention is suitable for flat and lightweight optical systems. It can be used as an optical window to improve the overall performance of instruments and equipment for solar-blind ultraviolet image intensifiers, and is of great significance in promoting the application and development of optical detection and imaging technologies.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a cross-section of a periodic array of micro-nano structures on the surface of the exit end face of the present invention; wherein, 1-substrate, 2-micro-nano structure functional layer, 3-solid micro-nano structure, 4-incident end face, 5-exit end face;

[0026] Figure 2 This is a side-view three-dimensional schematic diagram of a periodic array of micro-nano structures on the surface of the emission end face of the present invention; wherein, 1-substrate, 2-micro-nano structure functional layer, 3-solid micro-nano structure;

[0027] Figure 3This is a side-view stereoscopic diagram of a conventional transmissive optical element; where 1-substrate;

[0028] Figure 4 This is a schematic diagram (top view) of the distribution of the tetragonal close-packed periodic array micro / nano structure of the present invention;

[0029] Figure 5 This is a schematic diagram (top view) of the hexagonal close-packed periodic array micro / nano structure distribution of the present invention;

[0030] Figure 6A This is a schematic diagram of the conical micro / nano structure unit (conical shape) of the present invention;

[0031] Figure 6B This is a schematic diagram of the conical micro / nano structure unit (square cone shape) of the present invention;

[0032] Figure 6C This is a schematic diagram of the conical micro / nano structure unit (multi-faceted pyramid) of the present invention;

[0033] Figure 7A This is a schematic diagram of the frustum-shaped micro / nano structure unit (frustum shape) of the present invention;

[0034] Figure 7B This is a schematic diagram of the frustum-shaped micro / nano structure unit (square frustum shape) of the present invention;

[0035] Figure 7C This is a schematic diagram of the frustum-shaped micro / nano structure unit (multi-faceted frustum) of the present invention;

[0036] Figure 8A This is a schematic diagram of the micro / nano structure unit of the Gaussian surface shape of the present invention (Gaussian surface shape);

[0037] Figure 8B This is a schematic diagram of the micro / nano structure unit of the Gaussian surface of the present invention (side projection of the Gaussian surface);

[0038] Figure 8C This is a schematic diagram of the micro / nano structure unit of the Gaussian surface of the present invention (side projection of the flat-top Gaussian surface);

[0039] Figure 9A This is a schematic diagram of the cylindrical micro / nano structure unit (cylindrical) of the present invention;

[0040] Figure 9B This is a schematic diagram of the cylindrical micro / nano structure unit (square column) of the present invention;

[0041] Figure 9C This is a schematic diagram of the cylindrical micro / nano structure unit (polygonal prism) of the present invention. Detailed Implementation

[0042] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with preferred embodiments, details a quartz window for enhancing solar-blind ultraviolet detection, its preparation method, and its application, including its specific implementation, structure, features, and effects. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0043] Unless otherwise specified, all materials or reagents listed below are commercially available.

[0044] Some embodiments of the present invention provide a method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, comprising the following steps:

[0045] S1 uses a quartz substrate with high transmittance in the solar blind ultraviolet band as a transparent substrate (refractive index n = 1.5 @ 250 nm, transmittance ≥ 90% @ 250 nm). It is ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water to obtain a clean quartz substrate for later use.

[0046] S2 employs semiconductor industry-standard micro / nano structure precision fabrication technology to etch a periodic array of hollow micro / nano structures with gradually changing morphology onto the surface of the quartz substrate's emission end. These structures are arranged in a hexagonal or tetragonal close-packed pattern (e.g., ...). Figure 4 and Figure 5 (As shown). The top (tip) of the hollow morphology faces inward towards the substrate. The periodic array of hollow micro / nanostructures with gradually changing morphology includes multiple micro / nanostructure units, and the micro / nanostructure units have a conical morphology (e.g., ...). Figure 6A The cone shape shown Figure 6B The square pyramid shape shown Figure 6C The polygonal pyramid shape shown), frustum shape (such as...) Figure 7A The frustum shape shown Figure 7B The square-shaped structure shown is... Figure 7C The polygonal frustum shape shown), Gaussian surface shape (such as...) Figure 8A , Figure 8B The typical Gaussian surface shown is... Figure 8C The flat-topped Gaussian surface shown) or cylindrical (such as) Figure 9A The cylindrical shape shown Figure 9B The square column shown Figure 9CThe micro / nano structure unit (shown as a polygonal prism) has a bottom projection outline that is circular, square, or regular polygonal. The radius of the bottom projection circle / circumscribed circle R is 50nm–150nm, the radius of the top projection circle / circumscribed circle r ≤ 50nm, the period P is 100nm–300nm, the height / depth H is 80nm–300nm, and the duty cycle of the periodic array of the micro / nano structure is ≥0.5. The precision fabrication of the micro / nano structure includes etching, thin film deposition, and surface polishing at the micro / nano scale. Etching mainly includes electron beam writing (EBL), inductively coupled plasma etching (ICP), ion beam etching (IBE), and reactive ion beam etching (RIBE). Thin film deposition mainly includes atomic layer deposition (ALD), chemical vapor deposition (CVD), magnetron sputtering, electron beam evaporation, and laser pulse evaporation. Surface polishing mainly includes chemical mechanical polishing (CMP), plasma etching polishing, mechanical double-sided polishing, and mechanical single-sided polishing.

[0047] After S3 etching is completed, the photoresist is removed by mixing concentrated sulfuric acid, hydrogen peroxide, and deionized water (to remove photoresist) as needed. The photoresist is then removed by ultrasonic cleaning (power 28kHz) for 20 minutes by mixing 90wt% concentrated sulfuric acid and 30vol% hydrogen peroxide at a volume ratio of 1:2. This ultrasonic cleaning is repeated 3 times.

[0048] S4 is then subjected to alternating acid-base ultrasonic cleaning using dilute hydrofluoric acid and sodium hydroxide solution (which can corrode and remove quartz burrs, improving the surface morphology of the substrate); diluted hydrofluoric acid solution (concentration of 0.01 vol% to 0.5 vol%); and diluted strong alkali solution (concentration of 0.05 vol% to 3 vol%). This alternating acid-base method further improves the etching morphology. Finally, it undergoes ultrasonic cleaning with anhydrous ethanol / isopropanol, resulting in a clean optical element with a periodic array of hollow micro / nano structures with neat edges. The ultrasonic cleaning process parameters include: ultrasonic frequency of 80 kHz, temperature of 30°C, and ultrasonic time generally ranging from 1 to 10 minutes.

[0049] S5 employs vacuum thin-film fabrication technology to deposit a solar-blind ultraviolet-transmitting thin film material on the surface of the output end face of the aforementioned optical element as a filling material for the hollow structure. The refractive index of the thin film material must be greater than that of the transparent substrate, and it must have high transmittance in the working wavelength range (200nm–280nm). The thin film material can be one of the following: magnesium oxide, hafnium oxide, aluminum oxide, and zirconium oxide high-refractive-index high-transmittance ultraviolet thin films, or a composite film of at least two materials. Magnesium oxide, hafnium oxide, aluminum oxide, and zirconium oxide were selected because they have high transmittance in solar-blind ultraviolet light and their refractive index is higher than that of the quartz substrate.

[0050] S6 uses conventional polishing technology to polish the surface of the ejection end face after the above coating. Polishing removes excess thin film material and obtains a periodic array micro / nano structure functional layer with an embedded solid morphology and a thickness of 80nm to 300nm.

[0051] After S7 polishing, ultrasonic cleaning removes contaminants acquired during the processing, resulting in a novel surface micro / nanostructure transmission optical element with a periodic array of micro / nano structures on both ends. The incident micro / nano structure has no filling material, while the exit micro / nano structure is filled with a transparent thin film material with a high refractive index.

[0052] In the above technical solution, by constructing a submicron-scale micro / nano structure functional layer with a gradually varying refractive index, the morphology and distribution of the micro / nano structure are used to reduce the reflection and scattering of solar-blind ultraviolet light at the interface between the optical window and the photocathode, and to improve the solar-blind ultraviolet transmittance and diffraction efficiency. This, in turn, improves the photon absorption and quantum efficiency of the photocathode layer. Using this as the optical window of the solar-blind ultraviolet image intensifier can significantly improve the cathode sensitivity of the solar-blind ultraviolet image intensifier, thereby enhancing the long-distance, high-definition detection capabilities of related instruments and equipment to meet the high-end needs of related fields.

[0053] In some embodiments, optionally, a gradient high-refractive-index micro / nanostructure functional layer is fabricated on the exiting end face of the quartz substrate. This functional layer is composed of a periodic array of gradient high-refractive-index micro / nanostructures embedded in the surface of the exiting end face of the quartz substrate. The embedded periodic array's micro / nanostructure units are solid in shape and gradually increase in size along the exiting direction (e.g., ...). Figure 2 (As shown); the micro / nano structure unit is filled with a transparent thin film material, whose refractive index must be greater than that of the substrate, and it must have high transmittance in the solar blind band (200nm~280nm). One or more thin films of magnesium oxide, hafnium oxide, aluminum oxide and zirconium oxide or a composite film of at least two of them can be selected; the depth / height of the micro / nano structure unit is the thickness of the functional layer.

[0054] In some embodiments, optionally, the periodic arrays of micro-nano structures on the two end faces are hexagonal close-packed or tetragonal close-packed, the period P of the periodic array is 100nm to 300nm, the height / depth of the micro-nano structure unit is 80nm to 300nm, the duty cycle of the periodic array of micro-nano structures is ≥0.5, the morphology of the micro-nano structure unit is conical, frustum-shaped, Gaussian surface, or cylindrical, the bottom projection outline of the micro-nano structure unit is circular, square, or regular polygonal, the radius of the bottom projection circle / circumscribed circle radius R is 50nm to 150nm, and the radius of the top projection circle / circumscribed circle radius r ≤50nm.

[0055] The preferred period P is 100nm to 180nm. When P is less than 100nm, the transmission diffraction of the long-wavelength ultraviolet light near 280nm in the solar-blind ultraviolet region is fleeting, resulting in a limited increase in the total optical path length of photons in the photocathode layer, leading to low quantum efficiency. When P is greater than 180nm, the reflection diffraction of solar-blind ultraviolet light at the photocathode interface is significantly enhanced, resulting in increased reflectivity and a limited increase in transmittance, leading to low quantum efficiency. At the same time, it also leads to enhanced transmission diffraction of long-wavelength ultraviolet light outside the solar-blind ultraviolet range, resulting in enhanced extraspectral interference and reduced accuracy of solar-blind ultraviolet detection.

[0056] Some embodiments of the present invention also provide a quartz optical window for enhancing solar-blind ultraviolet detection. The quartz optical window includes a quartz substrate 1, which has an incident end face 4 for receiving and transmitting incident light and an opposing exit end face 5. The exit end face 5 of the quartz substrate 1 has a morphologically graded micro / nano structure periodic array functional layer 2, which includes multiple micro / nano structure units 3. Each micro / nano structure unit 3 is filled with a high-refractive-index solar-blind ultraviolet transparent thin film material to form a solid micro / nano structure periodic array. (See...) Figure 1 .

[0057] Quartz substrate 1 is used as the base material for the optical window because quartz has advantages such as high transmittance to solar-blind ultraviolet light, resistance to environmental corrosion, high mechanical strength, low price, and easy procurement. It is also the optical material commonly used in the field of solar-blind ultraviolet detection applications.

[0058] The fabrication of a micro / nano-structured functional layer on the emitting end face of the quartz substrate 1 is primarily driven by two factors. First, the refractive index of cesium telluride photocathodes used in solar-blind ultraviolet light is currently much higher than that of quartz, resulting in a significant difference in reflectivity between the photocathode and the quartz. Therefore, a functional layer with gradually increasing refractive index needs to be fabricated on the quartz emitting end face to reduce the refractive index difference between the quartz and cesium telluride photocathodes, thereby reducing reflectivity and improving solar-blind ultraviolet transmittance. Second, conventional quartz optical windows currently lack micro / nano structures, allowing solar-blind ultraviolet light to directly penetrate the photocathode for photoelectric conversion. Due to the short direct transmission path, the photoelectric conversion efficiency is low. By fabricating a micro / nano-structured functional layer of suitable size on the quartz emitting end face, the transmitted solar-blind ultraviolet light undergoes diffraction and interference, deflecting the transmission direction, increasing the transmission path, significantly improving the photoelectric conversion efficiency, and thus enhancing the cathode sensitivity.

[0059] Therefore, the functional layer of this micro / nano structure must be located between the quartz and the photocathode, the gradient refractive index must gradually increase along the transmission direction of solar-blind ultraviolet light, and the size specifications must meet the requirements of solar-blind ultraviolet operation.

[0060] First, by constructing a solid micro / nano structure periodic array on the emitting end face 5 of the quartz substrate 1, there are two main objectives. One is to achieve a refractive index gradient functional layer from the quartz substrate to the emitting end face through the micro / nano structure with a top-to-substrate gradient, thereby reducing the interfacial reflectivity between the emitting end face and the cesium telluride photocathode layer and improving the solar-blind ultraviolet transmittance. The other is to control the diffraction of solar-blind ultraviolet transmitted light by constructing a periodic array of micro / nano structures of appropriate size, thereby increasing the diffraction path and diffraction ratio of solar-blind ultraviolet light transmitted into the cesium telluride photocathode layer, and thus improving the quantum efficiency of the cesium telluride photocathode layer.

[0061] In the above technical solution, the present invention constructs a gradient high refractive index micro-nano structure array on its exit end surface, and uses the micro-nano structure morphology and structural distribution design to reduce light reflection and scattering at the interface between the quartz window and the cesium telluride photocathode, improve the solar-blind ultraviolet transmittance and diffraction efficiency at the interface, thereby improving the quantum efficiency of cesium telluride and achieving high cathode sensitivity. It can be used as an optical window to improve the comprehensive performance of solar-blind ultraviolet image intensifiers and other related instruments and equipment, and meet the high-end needs of related fields.

[0062] Using the aforementioned quartz optical window for enhancing solar-blind ultraviolet detection as an optical window to fabricate a cesium telluride photocathode, tests showed that at 250 nm, the interface reflectivity decreased to 1.9%-5.5%, the transmittance increased to 91.7%-95.3%, and the quantum efficiency increased to 23%-31%. Compared to conventional quartz optical windows, this represents a 50%-81% reduction in interface reflectivity, a 1.89%-5.89% increase in transmittance, and a 27.8%-72.2% increase in quantum efficiency.

[0063] In some embodiments, optionally, the top of the solid micro / nano structure periodic array at the entrance and exit ends faces the interior of the quartz substrate. The exit end has a solid shape, and the solid shape, i.e., the structure morphology, is filled with a high-transmittance ultraviolet thin film material with a higher refractive index than the quartz substrate. Because cesium telluride photocathode material is deposited on the exit end surface of the quartz substrate, when the top of the structure morphology faces the interior of the quartz substrate, a functional layer with a gradually changing refractive index from the quartz substrate to the cesium telluride photocathode layer is formed, reducing the abrupt change in refractive index at the interface. This achieves the purpose of reducing reflection and increasing transmission of the light emitted (transmitted light) from the quartz window / cesium telluride photocathode interface.

[0064] In some embodiments, the morphology of the micro-nano structure periodic array is optionally conical, frustum-shaped, Gaussian surface, or cylindrical, and its bottom projection profile on the plane is circular, square, or regular polygonal. The conical, frustum-shaped, and Gaussian surface are all gradually changing morphologies with inconsistent top and bottom sizes, while the cylindrical shape is a morphology with consistent top and bottom sizes. By constructing the above-mentioned micro-nano structure periodic array on the emitting end face of the quartz substrate, a refractive index transition effect can be constructed at the interface between the quartz optical window and the cesium telluride photocathode. The bottom contour of the micro / nano structure is circular, square, or regular polygonal. This shape is proposed in combination with hexagonal close-packed or tetragonal close-packed structures to achieve uniform diffraction of transmitted light at the interface. The period P of the structure is 100nm to 300nm, which is based on the diffraction effect on light in the 200-280nm wavelength band. When the period is less than 100nm, the transmission diffraction of light in the 200-280nm wavelength band almost disappears, and the diffraction efficiency is poor. As a result, the effect of increasing the optical path of transmitted light in the cesium telluride photocathode layer is not obvious, ultimately leading to a low quantum efficiency. When the period is greater than 300nm, the interface reflection diffraction of light in the 200-280nm wavelength band is enhanced, the reflectivity is high, the scattering is strong, the overall transmittance is poor, and multi-order diffraction and low diffraction efficiency occur. This leads to a decrease in the total number of photons transmitted into the cesium telluride photocathode layer and a decrease in the total optical path, ultimately resulting in a low quantum efficiency. The duty cycle of the bottom projection contour is ≥0.5. A larger duty cycle results in a better refractive index gradient effect, a smoother transition of the refractive index difference between the quartz window and the cesium telluride photocathode, and a lower interface reflectivity. When the duty cycle is less than 0.5, the refractive index gradient effect is poor, and the maximum duty cycle is 1.0. Therefore, the duty cycle of the micro / nano structure periodic array is ≥0.5. The radius of the circumcircle of the bottom projection is determined based on the duty cycle range, which is 50nm to 150nm. When the duty cycle is 0.5, for a period of 100nm, the radius of the circumcircle of the bottom projection is 50nm; when the duty cycle is 1.0, for a period of 300nm, the radius of the circumcircle of the bottom projection is 150nm. The radius of the circumcircle of the top projection is ≤20nm. The smaller the top, the better the refractive index gradient effect. When the radius of the circumcircle of the top projection is greater than 20nm, the refractive index gradient effect deteriorates significantly. Its height / depth is 80nm~300nm. The height / depth of the structure is to reduce the interface reflectivity, while ensuring that the transmission light diffraction efficiency in the cesium telluride photocathode layer reaches a high level, thereby achieving a high quantum efficiency.The structure height / depth is related to the period and the working wavelength. Generally, the structure height / depth is comparable to the period, but the larger the structure height / depth, the more significant the reduction in interface reflectivity. At the same time, since the transmission diffraction efficiency is related to the working wavelength (200-280nm), the structure height / depth is generally required to be in the range of 0.4 to 1.1 times the working wavelength for the solar-blind ultraviolet band. When the structure height / depth is too large or too small, it will lead to a significant reduction in diffraction efficiency. Therefore, considering all factors, the structure height / depth is set to 80nm to 300nm.

[0065] In some embodiments, optionally, the morphology of the plurality of said micro / nano structural units is the same; the periodic array must have the same and ordered morphological specifications, and only by forming a periodic array can there be a regular, controllable, and uniformly distributed light diffraction effect.

[0066] In some embodiments, optionally, the quartz substrate is made of quartz optical glass with a refractive index of 1.5 (the refractive index mentioned in this invention refers to the refractive index value corresponding to solar-blind ultraviolet light with a wavelength of 250 nm), and its effective transmittance in the 200 nm to 280 nm range is ≥90%; the refractive index of the transparent thin film material must be greater than that of the quartz substrate, and it must have high transmittance to ultraviolet light with a working wavelength of 200 nm to 280 nm. This transparent thin film material is used to fill the micro / nano structure morphology at the emission end face, aiming to construct a micro / nano structure functional layer with a gradually changing refractive index at the emission end face. Therefore, when selecting this thin film material, it is necessary to consider whether the refractive index of the thin film material is greater than that of the quartz substrate used, whether the transmission spectrum range of the thin film material matches the working wavelength range, whether the transmittance of the thin film material is high in the working wavelength range, and whether there is a stable and feasible thin film preparation scheme for the thin film material.

[0067] Some embodiments of the present invention also provide an optical device comprising the aforementioned quartz window for enhancing solar-blind ultraviolet detection. The quartz window of the present invention is only applicable to enhancing optical signal detection in the solar-blind ultraviolet band, and not to enhancing optical signal detection in other bands, because the size and material selection of the micro / nano structure functional layers must be customized according to the specific operating wavelength range, and are not universally applicable.

[0068] In some embodiments, optionally, the optical device is a solar-blind ultraviolet image intensifier. This invention is applicable to currently known solar-blind ultraviolet image intensifiers, and may also be applicable to other detection optics operating in the solar-blind ultraviolet band, depending on the specific circumstances of the other devices.

[0069] The present invention will be further described below with reference to specific embodiments.

[0070] Example 1:

[0071] S1 uses a 18*3mm quartz substrate (refractive index n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0072] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 (As shown in Figure 6). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 150kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 160nm, a duty cycle of 0.625, a depth / height of 110nm for the structure unit, and a circumcircle radius of 50nm for the bottom projection.

[0073] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0074] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0075] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 160 nm and a refractive index of 1.8@250 nm.

[0076] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 110 nm thick, magnesium oxide-filled, embedded, conical, periodic array micro / nano structure functional layer 2. Figure 2As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0077] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with magnesium oxide thin film material at the output end. The conical bottom circumcircle radius was 50nm, the period P was 160nm, and the height / depth was 110nm.

[0078] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 61%, transmittance at 250 nm is increased by 3.56%, and quantum efficiency is increased by 50%, as shown in Table 1.

[0079] Example 2:

[0080] S1 uses a 18*3mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0081] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 150kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 160nm, a duty cycle of 0.625, a depth / height of 300nm for the structure unit, and a circumscribed circle radius of 50nm for the bottom projection.

[0082] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0083] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0084] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 350 nm and a refractive index of 1.8@250 nm.

[0085] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 110 nm thick, magnesium oxide-filled, embedded, conical, periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0086] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with magnesium oxide thin film material at the output end. The conical bottom circumcircle radius was 50nm, the period P was 160nm, and the height / depth was 300nm.

[0087] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 65%, transmittance at 250 nm is increased by 3.89%, and quantum efficiency is increased by 44.4%.

[0088] Example 3:

[0089] S1 uses a 18*3mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0090] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 150kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 160nm, a duty cycle of 0.625, a depth / height of 80nm for the structure unit, and a circumcircle radius of 50nm for the bottom projection.

[0091] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0092] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0093] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 150 nm and a refractive index of 1.8@250 nm.

[0094] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 110 nm thick, magnesium oxide-filled, embedded, conical, periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0095] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with magnesium oxide thin film material at the output end; the radius of the circumscribed circle at the bottom of the cone is 50nm, the period P is 160nm, and the height / depth is 80nm.

[0096] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 59%, transmittance at 250 nm is increased by 3.33%, and quantum efficiency is increased by 38.9%.

[0097] Example 4:

[0098] S1 uses a 18*3mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0099] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 150kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 160nm, a duty cycle of 1, a depth / height of 110nm for the structure unit, and a circumscribed circle radius of 80nm for the bottom projection.

[0100] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0101] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0102] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 160 nm and a refractive index of 1.8@250 nm.

[0103] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 110 nm thick, magnesium oxide-filled, embedded, conical, periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0104] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with magnesium oxide thin film material at the output end. The conical bottom circumcircle radius was 80nm, the period P was 160nm, and the height / depth was 110nm.

[0105] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 77%, transmittance at 250 nm is increased by 4.78%, and quantum efficiency is increased by 61.1%, as shown in Table 1.

[0106] Comparative Example 1:

[0107] Following the preparation steps of Example 4, only the period P of the micro / nano structure was changed to 600 nm and the depth / height of the structural unit to 350 nm, while other parameters remained unchanged (duty cycle was 1). The corresponding circumcircle radius of the bottom projection was 300 nm, resulting in a periodic array micro / nano structure functional layer 2 with a period P of 600 nm, a duty cycle of 1, a depth / height of 350 nm for the structural unit, and an embedded conical solid filled with magnesium oxide. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0108] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 40%, transmittance at 250 nm is increased by 1.11%, and quantum efficiency is only increased by 2.8%, which cannot meet the requirements of high-performance solar-blind ultraviolet detection, as shown in Table 1.

[0109] Comparative Example 2:

[0110] Following the preparation steps of Example 4, only the period P of the micro / nano structure was changed to 60 nm, while other parameters remained unchanged (duty cycle of 1, depth / height of structural unit of 110 nm). The corresponding circumcircle radius of the bottom projection was 30 nm, resulting in a periodic array micro / nano structure functional layer 2 with a period P of 60 nm, a duty cycle of 1, a depth / height of 110 nm for structural unit, and an embedded conical solid filled with magnesium oxide. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0111] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes substrate 1a), whose interface reflectivity at 250 nm decreased by 44%, transmittance at 250 nm increased by 1.67%, and quantum efficiency increased by only 3.3%, which cannot meet the requirements of high-performance solar-blind ultraviolet detection, as shown in Table 1.

[0112] Example 5:

[0113] S1 uses a 40*5mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0114] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 150kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 300nm, a duty cycle of 1, a depth / height of 220nm for the structure unit, and a circumcircle radius of 150nm for the bottom projection.

[0115] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0116] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0117] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 270 nm and a refractive index of 1.8@250 nm.

[0118] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 220 nm thick, magnesium oxide-filled, embedded, conical, periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0119] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with magnesium oxide thin film material at the output end. The outer radius of the bottom circumcircle of the cone is 150nm, the period P is 300nm, and the height / depth is 220nm.

[0120] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 73%, transmittance at 250 nm is increased by 3.33%, and quantum efficiency is increased by 30.6%, as shown in Table 1.

[0121] Example 6:

[0122] S1 uses a 18*3mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0123] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 150kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 100nm, a duty cycle of 1, a depth / height of 80nm for the structure unit, and a circumcircle radius of 50nm for the bottom projection.

[0124] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0125] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0126] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 150 nm and a refractive index of 1.8@250 nm.

[0127] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 70 nm thick, magnesium oxide-filled, embedded, conical, periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0128] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with magnesium oxide thin film material at the output end; the radius of the circumscribed circle at the bottom of the cone is 50nm, the period P is 100nm, and the height / depth is 80nm.

[0129] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 67%, transmittance at 250 nm is increased by 3.78%, and quantum efficiency is increased by 32.2%, as shown in Table 1.

[0130] Example 7:

[0131] S1 uses a 25*4mm quartz substrate (refractive index n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0132] S2 employs inductively coupled plasma etching (ICP) to etch a periodic array of cylindrical hollow hexagonal close-packed micro / nano structures onto the surface of the quartz emission end (e.g., Figure 5 , Figure 9A (As shown). The etching process specifically includes: applying 300nm photoresist to the aforementioned end face surface via homogenization, followed by exposure and development to obtain a hexagonal close-packed circular hole array pattern with a radius of 50nm and a period P of 160nm; then, etching to obtain a quartz substrate pattern with a hexagonal close-packed circular hole array. The ICP etching parameters are set as follows: pre-evacuation vacuum degree is 1×10⁻⁶. -4 Ar was introduced as the sputtering gas at a flow rate of 60 sccm, and CF4 was used as the reactant gas at a flow rate of 20 sccm. The vacuum level inside the cavity was 2 Pa, the input power was 700 W, the bias power was 300 W, and a hollow array with a depth / height of 110 nm, a circular hole radius of 50 nm, a period P of 160 nm, and a duty cycle of 0.625 was obtained by etching.

[0133] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0134] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0135] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face as a filling material for the conical hollow micro / nano structure. Magnesium thiocyanate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 160 nm and a refractive index of 1.8@250 nm.

[0136] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, resulting in a 110 nm thick, magnesium oxide-filled, embedded cylindrical periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0137] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a cylindrical micro-nano structure filled with a periodic array of magnesium oxide thin film material at the output end. The bottom circumscribed circle of the cylinder has a radius of 50nm, a period P of 160nm, and a height / depth of 110nm.

[0138] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 50%, transmittance at 250 nm is increased by 2.78%, and quantum efficiency is increased by 27.8%, as shown in Table 1.

[0139] Example 8:

[0140] S1 uses a 18*3mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0141] S2 employs inductively coupled plasma etching (ICP) to etch a periodic array of flat-topped Gaussian hollow hexagonal close-packed micro / nano structures onto the surface of the aforementioned quartz emission end. The top of the flat-topped Gaussian surface faces inward toward the substrate (e.g., Figure 5 , Figure 8C (As shown). The etching process specifically includes: applying 300nm photoresist to the aforementioned end face surface via homogenization, followed by exposure and development to obtain a hexagonal close-packed array photoresist pattern with an outer radius of 50nm and a period P of 160nm; then etching to obtain a quartz substrate pattern with a hexagonal close-packed array. The ICP etching parameters are set as follows: pre-evacuation vacuum degree is 1×10⁻⁶. - 4Ar was introduced as the sputtering gas at a flow rate of 60 sccm, and CF4 was used as the reactant gas at a flow rate of 20 sccm. The vacuum level inside the cavity was 2 Pa, the input power was 700 W, the bias power was 300 W, and a flat-top Gaussian hollow array with a depth / height of 110 nm, a bottom circumscribed circle radius of 50 nm, a top circumscribed circle radius of 20 nm, a period P of 160 nm, and a duty cycle of 0.625 was obtained by etching.

[0142] S3. The quartz substrate with the above surface micro-nano structure was soaked in a mixture of concentrated sulfuric acid and 20 vol% hydrogen peroxide for 30 min, and then ultrasonically cleaned with deionized water and anhydrous ethanol for 5 min each (power 80 kHz). The ultrasonic cleaning was repeated 3 times to remove the mold, and a quartz substrate with a clean surface micro-nano structure was obtained.

[0143] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid solution, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol. This process is repeated 3 times (a chemical etching method of alternating acid and alkali erosion, which helps to further improve the etching morphology, and finally obtains a hollow body morphology array with a flat top Gaussian surface with neat edges).

[0144] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for a flat-top Gaussian hollow micro / nano structure. Magnesium thiocarbamate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 160 nm and a refractive index of 1.8@250 nm.

[0145] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, yielding a 110 nm thick, magnesium oxide-filled, embedded flat-top Gaussian solid periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0146] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and this cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants acquired during the transfer and operation of the sample). This resulted in a surface micro / nano structured transmission-type quartz optical element with a periodic array of conical micro / nano structures filled with magnesium oxide thin film material at the output end. The flat-top Gaussian surface has a bottom circumscribed circle radius of 50nm, a top circumscribed circle radius of 20nm, a period P of 160nm, and a height / depth of 110nm. Figure 8C As shown.

[0147] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 57%, transmittance at 250 nm is increased by 3.22%, and quantum efficiency is increased by 45%, as shown in Table 1.

[0148] Example 9:

[0149] S1 uses a 25*4mm quartz substrate (n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0150] S2 employs ion beam etching (IBE) to etch a periodic array of square-shaped hollow, densely packed micro / nano structures on the surface of the quartz substrate's emission end, with the tops of the square-shaped structures facing inwards towards the quartz interior (e.g., ...). Figure 4 , Figure 7B (As shown). The etching process specifically includes: coating the above-mentioned end face surface with 300nm photoresist through homogenization, and exposing and developing to obtain a tetragonal close-packed square hole array photoresist pattern with an outer circle radius of 50nm and a period P of 160nm; the reactive ion beam etching parameters are set as follows: the pre-vacuum degree is 1×10 -3 The sputtering gas was prepared at 80 sccm, with an Ar / O2 mixed gas (volume ratio of Ar:O2 = 4:1) introduced at a flow rate of 3 Pa. The ion beam energy was 320 eV, and the beam current density was 0.5 mA / cm². 2 The etching process yielded a frustum-shaped hollow array with a bottom circumcircle radius of 50nm, a top circumcircle radius of 20nm, a period P of 160nm, a depth / height of 110nm, and a duty cycle of 0.625.

[0151] S3. The quartz substrate with the above surface micro-nano structure was soaked in a mixture of concentrated sulfuric acid and 20 vol% hydrogen peroxide for 30 min, and then ultrasonically cleaned with deionized water and anhydrous ethanol for 5 min each (power 80 kHz). The ultrasonic cleaning was repeated 3 times to remove the mold, and a quartz substrate with a clean surface micro-nano structure was obtained.

[0152] S4 The cleaned quartz substrate with micro-nano structure is cleaned by ultrasonication (power 80kHz) for 1 minute each in a 0.2 vol% dilute hydrofluoric acid solution, a 2 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology and finally obtain a square platform morphology with neat edges).

[0153] S5 employs atomic layer deposition (ALD) technology to deposit a magnesium oxide thin film on the aforementioned exit end face surface as a filling material for a flat-top Gaussian hollow micro / nano structure. Magnesium thiocarbamate (Mg(C5H5)2) is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 200℃, and the growth rate is 0.1 nm / cycle, resulting in a magnesium oxide film layer with a thickness of 160 nm and a refractive index of 1.8@250 nm.

[0154] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 70 rpm rotation speed and 6 g / mm pressure. 2 The polishing slurry flow rate was 2 mL / min. Polishing removed excess magnesium oxide film, yielding a 110 nm thick, magnesium oxide-filled, embedded flat-top Gaussian solid periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with magnesium oxide and form a solid micro / nano structure periodic array.

[0155] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of frustum-shaped micro-nano structures filled with magnesium oxide thin film material at the output end. The frustum-shaped structure has a bottom circumscribed circle radius of 50nm, a top circumscribed circle radius of 20nm, a period P of 160nm, and a height / depth of 110nm.

[0156] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3As shown, it includes a substrate 1a), whose reflectivity at 250 nm is reduced by 45%, transmittance at 250 nm is increased by 1.89%, and quantum efficiency is increased by 35%, as shown in Table 1.

[0157] Example 10:

[0158] S1 uses a 18*3mm quartz substrate (refractive index n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0159] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4 The maximum accelerating voltage is 100kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 160nm, a duty cycle of 1, a depth / height of 110nm for the structure unit, and a circumscribed circle radius of 80nm for the bottom projection.

[0160] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0161] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0162] S5 employs atomic layer deposition (ALD) technology to deposit a hafnium oxide thin film on the aforementioned exit end face surface as a filling material for the conical hollow micro / nano structure. Tetraethylaminohafnium is used as a precursor, H2O as a reactant, N2 as a carrier gas, the reaction temperature is 250°C, and the hafnium oxide growth rate is 0.1 nm / cycle, resulting in a hafnium oxide film layer with a thickness of 160 nm and a refractive index of 2.12@250 nm.

[0163] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 90 rpm rotation speed and 8 g / mm pressure. 2 The polishing slurry flow rate was 3 mL / min. Polishing removed excess hafnium oxide film, resulting in a 110 nm thick, hafnium oxide-filled, embedded conical solid periodic array micro / nano structure functional layer 2. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with hafnium oxide and form a solid micro / nano structure periodic array.

[0164] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and the cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample was exposed to during the transfer and operation process). This resulted in a surface micro-nano structure transmission-type quartz optical element with a periodic array of conical micro-nano structures filled with hafnium oxide thin film material at the output end. The outer radius of the bottom circumcircle of the cone is 80nm, the period P is 160nm, and the height / depth is 110nm.

[0165] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 81%, transmittance at 250 nm is increased by 5.89%, and quantum efficiency is increased by 72.2%, as shown in Table 1.

[0166] Example 11:

[0167] S1 uses a 18*3mm quartz substrate (refractive index n=1.5@250nm) as a transparent substrate. It is cleaned by ultrasonic cleaning (power 45kHz) for 5 minutes each with acetone, anhydrous ethanol and deionized water. The cleaning is repeated 3 times to obtain a clean quartz substrate for use.

[0168] S2 employs electron beam writing (EBL) technology to etch a periodic array of hexagonal close-packed micro / nano structures in a conical hollow body onto the surface of the quartz substrate, with the top of the cone facing inwards towards the quartz (e.g., Figure 5 , Figure 6A (As shown). The operating parameters of the electron beam direct writing technology are as follows: working vacuum degree is 5×10⁻⁶. -4The maximum accelerating voltage is 100kV, the scanning frequency is 12MHz, the scanning step size is 2nm, and the minimum beam spot size is 3nm. The conical micro / nano structure periodic array includes multiple conical micro / nano structure units, and the etched periodic array is a conical hollow micro / nano structure with a period P of 160nm, a duty cycle of 1, a depth / height of 110nm for the structure unit, and a circumscribed circle radius of 80nm for the bottom projection.

[0169] After S3 etching, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 80kHz). The ultrasonic cleaning was repeated 3 times (to remove organic contaminants, grease, and dust contaminants that the sample was exposed to during the transfer and operation process).

[0170] S4 is then cleaned by ultrasonication (power 80kHz) for 1 minute each with a concentration of 0.01 vol% dilute hydrofluoric acid, a concentration of 0.1 wt% sodium hydroxide solution, and anhydrous ethanol, and the ultrasonication is repeated 3 times (a chemical etching method of alternating acid and alkali erosion to further improve the etching morphology), finally obtaining a periodic array of micro-nano structures with a neatly edged conical hollow body morphology.

[0171] S5 employs atomic layer deposition (ALD) technology to deposit a zirconia / alumina composite film on the exit end face of the aforementioned glass. Tetramethylaminozirconium and trimethylaluminum are used as precursors, H2O as reactant, N2 as carrier gas, and the reaction temperature is 90℃. The zirconia growth rate is 0.1 nm / cycle, and the alumina growth rate is 0.05 nm / cycle, resulting in a zirconia / alumina composite film with a thickness of 160 nm and a refractive index of 2.0 (zirconia:alumina = 1:5 (thickness ratio)).

[0172] S6 employs chemical mechanical polishing (CMP) to polish the surface of the ejector end face after coating, using process parameters of 100 rpm and 8 g / mm² pressure. 2 The polishing slurry flow rate was 3 mL / min. Polishing removed excess zirconium oxide / alumina composite film, yielding a 110 nm thick, periodic array micro / nano structure functional layer 2, consisting of an embedded conical solid body filled with zirconium oxide / alumina composite film. Figure 2 As shown, the micro / nano structure periodic array functional layer 2 includes multiple micro / nano structure units 3; the micro / nano structure units 3 are filled with zirconium oxide / alumina composite film layers to form a solid micro / nano structure periodic array.

[0173] After S7 polishing, the sample was ultrasonically cleaned for 5 minutes each with acetone, anhydrous ethanol, and deionized water (power 45kHz), and this cleaning was repeated 3 times (to remove organic matter, dust, particles, and other contaminants that the sample had acquired during the transfer and operation process). This resulted in a surface micro / nano structured transmission-type quartz optical element with a periodic array of conical micro / nano structures filled with zirconium oxide / alumina composite thin film material at the output end. The conical bottom circumcircle radius was 80nm, the period P was 160nm, and the height / depth was 110nm.

[0174] Using the aforementioned surface micro / nano structured transmissive quartz optical element as an optical window to fabricate a cesium telluride photocathode, compared to conventional quartz optical windows (such as... Figure 3 As shown, it includes a substrate 1a), whose interface reflectivity at 250 nm is reduced by 80%, transmittance at 250 nm is increased by 5.78%, and quantum efficiency is increased by 61.7%, as shown in Table 1.

[0175] The performance data of the quartz optical windows with micro / nano structure functional layers obtained in Examples 1-11 and Comparative Examples 1-2, as well as conventional quartz optical windows, are summarized in Table 1. The transmittance of their exit faces was tested using the quartz optical windows with micro / nano structure functional layers obtained in Examples 1-11 and Comparative Examples 1-2, as well as conventional quartz optical windows, as optical windows. Quartz optical windows with cesium telluride photocathodes were formed by vapor deposition of cesium telluride photocathodes, and their interface reflectivity and quantum efficiency were tested under the same conditions.

[0176] Transmittance is measured using an ultraviolet spectrometer under 250nm incident light through a quartz window.

[0177] Interface reflectance is the reflectance of the emitting end interface of a quartz window with a cesium telluride photocathode measured by an ultraviolet spectrometer under 250nm incident light.

[0178] Quantum efficiency is measured using a quantum efficiency meter to determine the number of photogenerated electrons corresponding to a 250nm photon passing through a quartz window and illuminating a cesium telluride photocathode.

[0179] Table 1

[0180]

[0181] As can be seen from the data in Table 1, the quartz optical windows with micro-nano structure functional layers obtained in Examples 1-11 of the present invention have a transmittance of 91.7%-95.3% at a working wavelength of 250nm, an interface reflectance of 1.9%-5.5%, and a quantum efficiency of 23.00%-31.00%.

[0182] Comparing Examples 1, 2, and 3, it can be seen that when other parameters remain constant, only changing the depth / height of the micro / nano structure within the range of 80nm-300nm, as the depth / height of the micro / nano structure gradually increases, the reflectivity of the exit interface decreases, while the transmittance of the optical window increases. However, the quantum efficiency of the corresponding cesium telluride photocathode shows a trend of first increasing and then decreasing, indicating that the quantum efficiency does not entirely depend on the transmittance but also on the size optimization of the periodic array structural units of the micro / nano structure. Experimental verification shows that when the depth / height of the micro / nano structure is 0.5-2 times the period P, the corresponding diffraction utilization efficiency is generally higher. Generally, the greater the depth / height of the micro / nano structure, the better the refractive index gradient effect and the smaller the reflection of the functional layer of the micro / nano structure.

[0183] Comparing Examples 1 and 4, it can be seen that when other parameters remain unchanged, only the duty cycle of the periodic array of the micro / nano structure is changed. The larger the duty cycle, the higher the transmittance, the lower the interface reflectance, and the higher the quantum efficiency. Since the micro / nano structure is an embedded high-refractive-index solid micro / nano structure, the larger the duty cycle, the larger the corresponding refractive index gradient value at the emission end interface, and the smaller the deviation from the large refractive index of the cesium telluride photocathode. This indicates that the smaller the refractive index deviation at the emission end, the higher the solar-blind ultraviolet transmittance, the more solar-blind ultraviolet photons participate in photoelectric conversion, and the higher the corresponding quantum efficiency.

[0184] Comparing Example 4, Comparative Example 1, and Comparative Example 2, it can be seen that the period of the micro / nano structure array has a significant impact on the quantum efficiency of the cesium telluride photocathode. Verification shows that the suitable period P for the micro / nano structure in solar-blind ultraviolet light is within the range of 100nm-300nm. When the period P is higher than 300nm, on the one hand, multi-order diffraction occurs, reducing diffraction efficiency and thus lowering quantum efficiency; on the other hand, different periods P are suitable for different operating wavelengths. When the period P is higher than 300nm, such as 600nm, it is suitable for the near-infrared band, but if used in the solar-blind ultraviolet band, it will result in persistently high solar-blind ultraviolet reflection, limiting the improvement of quantum efficiency and failing to meet the requirements of high-performance solar-blind ultraviolet detection equipment. When the period P is lower than 100nm, such as 60nm, it causes significant evanescence of the diffracted wave in the solar-blind ultraviolet portion of the transmitted light, leading to a reduction in the increased photon optical path effect caused by diffraction, resulting in a decrease in quantum efficiency and failing to meet the requirements of high-performance solar-blind ultraviolet detection equipment.

[0185] Comparing Examples 4, 5, and 6, it can be seen that when the duty cycle is the same and the utilization efficiency of transmitted diffracted light corresponding to the structure depth / height is high, there is an optimized value for the micro / nano structure period P for the solar-blind ultraviolet quantum efficiency, which is between 120nm and 180nm.

[0186] Comparing Examples 1, 7, 8, and 9, it can be seen that when the period, duty cycle, and depth / height of the micro / nano structure array remain constant, the quantum efficiency corresponding to different structural morphologies also varies. The comparison shows that the conical and flat-topped Gaussian morphologies correspond to higher quantum efficiencies, while the cylindrical and frustum morphologies correspond to lower quantum efficiencies. The conical and flat-topped Gaussian morphologies are gradient morphologies, constructing a micro / nano structure functional layer with a gradually changing refractive index. This reduces interface reflectivity and enhances transmittance, thereby increasing the number of solar-blind ultraviolet photons participating in the photoelectric conversion of the cesium telluride photocathode, resulting in higher quantum efficiency. The cylindrical morphology, however, is not a gradient morphology and only acts as a buffer against refractive index deviations. Therefore, its effect on reducing interface reflectivity and increasing transmittance is limited, leading to lower quantum efficiency. Although the truncated pyramidal morphology is a gradient morphology, the area of ​​the square cross-section is smaller than the area of ​​its circumscribed circle. In other words, the equivalent refractive index of the truncated pyramidal morphology is lower than that of other circular cross-sections such as conical and flat-top Gaussian shapes with the same bottom circumscribed circle. Therefore, the gradient refractive index value of the truncated pyramidal morphology is smaller, resulting in a larger refractive index deviation from that of the cesium telluride photocathode. Consequently, the quantum efficiency corresponding to the truncated pyramidal morphology is lower.

[0187] Comparing Examples 4, 10, and 11, it can be seen that when the period, duty cycle, and depth / height of the micro / nano structure array remain constant, the quantum efficiency varies depending on the filling thin film material. The comparison shows that the higher the refractive index of the filling material, the higher the quantum efficiency tends to be. This is because when the micro / nano structure morphology and size are the same, the higher the refractive index of the filling thin film material, the higher the refractive index of the corresponding solid micro / nano structure, and the smaller the refractive index deviation between it and the cesium telluride photocathode. This results in a decrease in interface reflectivity and an increase in transmittance, leading to an increase in the number of solar-blind ultraviolet photons entering the cesium telluride photocathode film layer to participate in photoelectric conversion, thus increasing the quantum efficiency.

[0188] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0189] The microstructures described in this invention, and any simple deposition of a film layer on the surface of the microstructure to modify, protect, or passivate the microstructure surface, shall be within the scope of protection of this invention.

[0190] The numerical range described in this invention includes all values ​​within this range, and also includes any range value composed of any two values ​​within this range. Different values ​​of the same indicator appearing in all embodiments of this invention can be arbitrarily combined to form a range value.

[0191] The technical features in the claims and / or specification of this invention can be combined, and the combination is not limited to the combinations obtained through reference in the claims. Technical solutions obtained by combining the technical features in the claims and / or specification are also within the scope of protection of this invention.

[0192] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection, characterized in that, Includes the following steps: 1) A periodic array of hollow micro / nano structures with gradually changing morphology is etched on the emitting end face of a clean, solar-blind, high-transmittance quartz substrate. After multiple ultrasonic cleanings, a clean quartz element with a periodic array of hollow micro / nano structures with neat edges is obtained. The periodic array of hollow micro / nano structures with gradually changing morphology includes multiple micro / nano structure units. The micro / nano structure units have a cone, frustum, Gaussian surface, or cylindrical shape. The bottom projection outline of the micro / nano structure unit is circular, square, or regular polygonal. The radius of the bottom projection circle / circumscribed circle is 50 nm to 150 nm, the radius of the top projection circle / circumscribed circle is less than or equal to 50 nm, the period is 100 nm to 300 nm, the height / depth is 80 nm to 300 nm, and the duty cycle of the periodic array of micro / nano structures is greater than or equal to 0.

5. 2) A thin film material with high solar blind ultraviolet transmittance is deposited on the emitting end surface of the quartz element obtained in step 1) as the filling material for the hollow structure; 3) Polish the exit end face after coating in step 2) to obtain a micro-nano structure periodic array functional layer with an embedded solid morphology of 80nm~300nm thickness. Then, ultrasonic cleaning is performed to obtain a quartz window for enhancing solar-blind ultraviolet detection with a micro-nano structure periodic array.

2. The method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection as described in claim 1, characterized in that, In step 1), the quartz substrate has a refractive index n=1.5 at a wavelength of 250nm and a transmittance ≥90% at a wavelength of 250nm; the hollow micro-nano structure periodic array is distributed in a hexagonal close-packed or tetragonal close-packed manner; the top of the hollow micro-nano structure periodic array faces the interior of the quartz substrate.

3. The method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection as described in claim 1, characterized in that, In step 1), the ultrasonic cleaning includes conventional ultrasonic cleaning, alternating acid-base ultrasonic cleaning, and anhydrous ethanol / isopropanol ultrasonic cleaning.

4. The method for preparing a quartz optical window for enhancing solar-blind ultraviolet detection as described in claim 1, characterized in that, In step 2), the refractive index of the thin film material is greater than that of the transparent substrate, and it is transparent to ultraviolet light with a working wavelength of 200 nm to 280 nm; the thin film material is selected from one thin film of magnesium oxide, hafnium oxide, aluminum oxide and zirconium oxide or a composite thin film of at least two materials.

5. A quartz optical window for enhancing solar-blind ultraviolet detection, characterized in that, The quartz optical window for enhancing solar-blind ultraviolet detection includes a quartz substrate. The quartz substrate has an incident end face for receiving and transmitting incident light and an opposing exit end face. The exit end face of the quartz substrate has a hollow micro / nano structure periodic array with a gradually changing morphology. The micro / nano structure periodic array includes multiple micro / nano structure units. The micro / nano structure units of the exit end face are filled with a transparent thin film material with a high refractive index to form a solid micro / nano structure periodic array. The morphology of the hollow micro / nano structure periodic array is conical, frustum-shaped, Gaussian surface, or cylindrical. Its bottom projection outline on the plane is circular, square, or regular polygonal. The radius of the bottom projection circle / circumscribed circle R is 50 nm to 150 nm, the radius of the top projection circle / circumscribed circle r ≤ 50 nm, the period P is 100 nm to 300 nm, the height / depth H is 80 nm to 300 nm, and the duty cycle of the micro / nano structure periodic array is ≥ 0.

5.

6. The quartz window for enhancing solar-blind ultraviolet detection as described in claim 5, characterized in that, The quartz substrate has a refractive index of 1.5 and an effective transmittance of ≥90% in the 200 nm to 280 nm range; the transparent thin film material has a refractive index greater than that of the quartz substrate and is transparent to ultraviolet light with a working wavelength of 200 nm to 280 nm.

7. An optical device, characterized in that, It includes a quartz optical window for enhancing solar-blind ultraviolet detection; the quartz optical window for enhancing solar-blind ultraviolet detection includes a quartz substrate, the quartz substrate having an incident end face for receiving and transmitting incident light and an opposing exit end face, the exit end face of the quartz substrate having a hollow micro-nano structure periodic array with gradually changing morphology, the micro-nano structure periodic array including multiple micro-nano structure units; the micro-nano structure units of the exit end face are filled with a transparent thin film material with high refractive index to form a solid micro-nano structure periodic array; the morphology of the hollow micro-nano structure periodic array is conical, frustum-shaped, Gaussian surface, or cylindrical, its bottom projection outline on the plane is circular, square, or regular polygonal, its bottom projection circle radius / circumscribed circle radius R is 50 nm~150 nm, its top projection circle radius / circumscribed circle radius r ≤ 50 nm, the period P is 100 nm~300 nm, and the height / depth H is 80 nm~300 nm. nm, the duty cycle of the micro / nano structure periodic array is ≥0.

5.

8. The optical device as described in claim 7, characterized in that, The optical device is a solar-blind ultraviolet image intensifier.

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