Glass vacuum cavity and manufacturing method

Abstract

The invention belongs to the field of advanced scientific devices integrating optics, quantum mechanics, atomic physics and a vacuum technology, and particularly relates to a glass vacuum cavity and a manufacturing method thereof.The manufacturing method includes the steps that the inner surfaces of window pieces are machined firstly, an inner working face with high surface shape precision can be obtained, and after the inner surfaces are machined, the four window pieces are plated with films, and the working faces are plated with antireflection films; the optical cement surface is plated with an optical cement auxiliary film, and the diffraction film is rubbed after the optical cement surface is plated with the film, so that the optical cement strength is ensured to be optimal. After every two of the four window sheets are subjected to optical cement deepening, the outer surfaces are processed, and when the outer surfaces are processed, the inner surfaces are protected, so that the quality of a film layer is not damaged. By means of the method that optical processing, film coating and optical cement deepening are conducted on the inner surface alternately, and then optical processing, film coating and optical cement deepening are conducted on the outer surface alternately, the glass vacuum cavity which is high in window piece surface shape precision, high in window piece parallel precision, high in combination strength and good in air tightness, and the film layer surface quality is not prone to pollution or damage can be machined.

Description

Technical Field

[0001] The present invention belongs to the field of advanced scientific devices integrating optics, quantum mechanics, atomic physics and vacuum technology, and particularly relates to a glass vacuum chamber and a manufacturing method thereof. Background Art

[0002] In recent years, the quantum control technology has developed rapidly. Among them, atomic interferometers have received extensive attention and research worldwide due to their ultra-high theoretical precision potential. Sensors based on cold atom interferometers can be widely used in the fields of precise measurement of physical parameters, time measurement and frequency standards, geological exploration, inertial navigation, etc., and have important application prospects. In a cold atom interferometer, an ultra-high vacuum cavity is often required to ensure the coherence of atoms; at the same time, the vacuum cavity is also required to have good optical accessibility to ensure the coherent manipulation of atoms by lasers. These requirements are usually realized by using a glass vacuum chamber. At present, the structure of the glass vacuum chamber is a glass-metal sealing structure, that is, the glass vacuum chamber is sealed to a metal flange tube by welding, and then sealed to the main cavity by using the knife-edge structure of the metal flange. This structure has the following problems: the thermal expansion coefficients of the glass and metal alloy materials need to be basically the same or relatively close, or when they differ greatly, the metal is required to have good ductility and plasticity to be sealed. A large difference in thermal expansion coefficients will cause air leakage or bursting at the interface. This limits the selection of glass and metal materials. In atomic interferometers, non-magnetic titanium alloys or 316L stainless steel materials are often used as the materials for the metal flange, and quartz and pyrex glass are used as the materials for the glass cavity. It is very difficult to seal the metal flange and the glass cavity. To solve this problem, in practical applications, metals and glass materials with similar thermal expansion coefficients can be first sealed, and then transition glass tubes can be fired using glass materials with different thermal expansion coefficients, so that the thermal expansion coefficient gradually transitions from the fired sealing material to the pre-prepared glass vacuum chamber to achieve the purpose of sealing. However, when using this method, the flame temperature is relatively high during firing, which will damage the surface coating of the glass vacuum chamber, and the surface of the glass cavity is extremely easy to be contaminated during the firing process, which will greatly reduce the optical accessibility quality of the cavity. For the assembly of the glass cavity itself, usually ① high-temperature bonding: that is, the glass is attached together by high temperature and pressed to achieve a tight bonding effect. High-temperature bonding will cause deformation of the glass surface, and the surface and film layer of the glass cavity will be damaged, affecting its performance. ② Low-temperature bonding: that is, hydroxide-catalyzed bonding, and a three-dimensional silicate network structure is formed between the bonding interfaces by using a bonding liquid containing hydroxide to achieve bonding. However, this method will also damage the glass surface and film layer quality to a certain extent. For the above reasons, the existing structure of the glass vacuum chamber has the disadvantages of difficult assembly of the glass cavity, low assembly strength, easy fragmentation, and easy contamination of the film layer surface of the glass cavity. Summary of the Invention

[0003] The object of the present invention is to provide a glass vacuum chamber and a manufacturing method thereof, so as to solve the problems in the prior art that the structure of the glass vacuum chamber has difficulties in assembling the glass cavity, low assembling strength, easy to break, and easy to contaminate the film surface of the glass cavity.

[0004] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present application discloses a glass vacuum chamber, including a glass chamber, the glass chamber being a cuboid composed of six glass window panes. A through hole is centrally provided in one glass window pane of the cuboid, and one end of a flange glass assembly is adhesively connected along the axial direction at the through hole. The other end of the flange glass assembly is connected with a flange blind plate, and a sealing gasket is arranged between the flange glass assembly and the flange blind plate.

[0005] Preferably, the flange glass assembly includes a quartz tube. One end of the quartz tube is adhesively connected with the glass chamber, and the other end is connected with a kovar metal tube. The kovar metal tube is connected with a CF vacuum flange, and the CF vacuum flange is connected with the flange blind plate.

[0006] Preferably, one end of the kovar metal tube is connected with the CF vacuum flange by continuous argon arc welding, and the other end is connected with the quartz tube by burning and forging.

[0007] Preferably, the CF vacuum flange and the flange blind plate are connected by bolts. Six bolt holes are provided on both the CF vacuum flange and the flange blind plate. Leak detection grooves are provided on the contact surfaces of the CF vacuum flange and the flange blind plate, and the sealing gasket is installed at the leak detection grooves.

[0008] Preferably, in the glass chamber, the vertical angle between each glass window pane is ≤ 1″, the surface roughness Ra is not greater than 1.2 Å, and the surface figure is not greater than λ / 20.

[0009] Preferably, in the glass chamber, the material of the sealing gasket is oxygen-free highly conductive copper.

[0010] In a second aspect, the present application discloses a manufacturing method of a glass vacuum chamber, including: S1: Assemble the flange glass assembly and the flange blind plate into one body for standby. Optically process the inner surface and the side surface of the glass window pane to obtain a polished glass window pane, and divide it into an inner surface working area, an outer surface working area, an inner surface adhesive area, and a side surface adhesive area according to the functional areas of the polished glass window pane; S2: Deposit technical index films on the inner surface working area and the outer surface working area, and deposit adhesive auxiliary films on the inner surface adhesive area and the side surface adhesive area; polish the adhesive auxiliary films in the adhesive areas to remove the diffraction films to obtain a secondary polished glass window pane; S3: The inner surface photo-bonding area of the secondarily polished glass window pane is photo-bonded with the side surface photo-bonding area of another polished glass window pane to obtain a cuboid glass chamber, and deep bonding is performed; S4: The assembled flange glass assembly and the flange blank are photo-bonded to one end of the flange glass assembly on the end surface of the glass chamber to form a glass vacuum chamber.

[0011] Preferably, in the step S1, the classical polishing method is used to polish the glass window pane to obtain a polished glass window pane, and among the six polished glass window panes, the sizes of the two opposite polished glass window panes are the same.

[0012] Preferably, the step S3 specifically includes: S301: Take four secondarily polished glass window panes on which the technical index film layer and the photo-bonding auxiliary film are plated. The inner surface photo-bonding area of the polished glass window pane is photo-bonded with the side surface photo-bonding area of another polished glass window pane to obtain a "mouth"-shaped window pane; S302: Perform deepening treatment on the "mouth"-shaped window pane to obtain a deepened "mouth"-shaped window pane; S303: Apply a protective paint to the working area of the inner surface of the deepened "mouth"-shaped window pane; after filling the inside of the deepened "mouth"-shaped window pane with a grinding aid block, polish the two end faces of the deepened "mouth"-shaped window pane to obtain the photo-bonding area of the "mouth"-shaped window pane; remove the grinding aid block and the protective paint in sequence; S304: Plate a photo-bonding auxiliary film on the photo-bonding areas of the two end faces of the "mouth"-shaped window pane; polish the photo-bonding auxiliary film to remove the diffraction film; S305: Respectively photo-bond the photo-bonding areas of the "mouth"-shaped window pane with the other two polished glass window panes and then deepen to obtain a cuboid glass chamber.

[0013] Preferably, when photo-bonding the four polished glass window panes in the step S301, the parallelism of the two opposite polished glass window panes is < 5″, and there are no air bubbles, dirt spots or scratches at the photo-bonding joint to obtain a "mouth"-shaped window pane.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In the present application, the glass chamber and the flange glass assembly are designed and processed separately, and are assembled into one body. It can be independently processed in parallel for the two parts, saving processing time and reducing time cost. Moreover, it can avoid damaging the surface finish and the surface form accuracy of the glass chamber during the welding and burning processes of the flange glass assembly. Most importantly, it can also avoid damaging the surface film layer quality, thereby avoiding affecting the optical performance of the entire chamber.

[0015] The manufacturing method of the present application first optically processes the inner surface and the optical cementing surface of the glass chamber window, completes the film coating on the inner surface and the optical cementing surface, and then performs optical cementing deepening on the two sets of opposite windows; then performs optical processing on the outer surfaces of the two sets of opposite windows, then performs film coating on the outer surfaces, and finally performs optical cementing deepening on the two end face windows, which can not only ensure the high surface shape accuracy requirements of a single window itself, but also ensure that the film quality on the window surface is not damaged or polluted. Through a processing flow of optical processing, film coating, optical cementing deepening, then optical processing, film coating, and finally complete optical cementing deepening, it can not only ensure the parallelism accuracy of the two opposite windows, but also ensure the assembly accuracy and assembly strength after the combination of the glass chambers, and at the same time ensure the airtightness of the overall glass chamber. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a glass chamber diagram of the present invention; Figure 2 It is a schematic diagram of the optical cementing combination process of the glass chamber of the present invention; Figure 3 It is a schematic diagram of the flange glass assembly of the present invention; Figure 4 It is an exploded view of the overall mechanism of the present invention; Figure 5 It is a schematic diagram of the overall mechanism of the present invention; Figure 6 It is an axial sectional view of the present invention; Figure 7 It is a schematic diagram of the method for optically processing and mounting a single window of the glass chamber of the present invention; Figure 8 It is a schematic diagram of the angle correction tooling of the present invention.

[0018] Among them, 1 - glass chamber; 2 - flange glass assembly; 201 - quartz tube; 202 - kovar metal tube; 203 - CF vacuum flange; 3 - sealing gasket; 4 - flange blind plate; 5 - window; 6 - mounting plate bonding sealing wax ball; 7 - mounting plate backing plate; 8 - first film coating position; 9 - second film coating position. Detailed Embodiments

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0022] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0023] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0024] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The following further describes the present invention in detail with reference to the accompanying drawings: The present application discloses that a glass vacuum chamber which can not only ensure an ultra-high vacuum degree, but also achieve high-quality double-sided coating of optical window wafers, can not only ensure the assembly strength, but also reduce the assembly difficulty has become an urgent scientific research and market demand. See Figure 4 A glass vacuum chamber, comprising a glass chamber 1, the glass chamber 1 being a cuboid composed of six glass window wafers. A through hole is provided in the middle of one glass window wafer of the cuboid, and one end of a flange glass assembly 2 is optically cemented along the axial direction at the through hole. The other end of the flange glass assembly 2 is connected with a flange blind plate 4, and a sealing gasket 3 is arranged between the flange glass assembly 2 and the flange blind plate 4.

[0026] In some embodiments, the flange glass assembly 2 includes a quartz tube 201. One end of the quartz tube 201 is optically cemented with the glass chamber 1, and the other end is connected with a kovar metal tube 202. The kovar metal tube 202 is connected with a CF vacuum flange 203, and the CF vacuum flange 203 is connected with the flange blind plate 4.

[0027] In some embodiments, one end of the kovar metal tube 202 is connected with the CF vacuum flange 203 by continuous argon arc welding, and the other end is connected with the quartz tube 201 by burning and fusing.

[0028] In some embodiments, the CF vacuum flange 203 is connected with the flange blind plate 4 by bolts. Six bolt holes are provided on both the CF vacuum flange 203 and the flange blind plate 4, and leak detection grooves are provided on the contact surfaces of the CF vacuum flange 203 and the flange blind plate 4. The sealing gasket 3 is installed at the leak detection grooves.

[0029] In some embodiments, in the glass chamber 1, the vertical angle between each glass window wafer is ≤1″, the surface roughness Ra is not greater than 1.2 angstroms, and the surface form is not greater than λ / 20.

[0030] In some embodiments, in the glass chamber 1, the material of the sealing gasket 3 is oxygen-free highly conductive copper.

[0031] The present application also discloses a manufacturing method of a glass vacuum chamber, comprising: S1: Assemble the flange glass assembly 2 and the flange blind plate 4 into one unit for standby. Optically process the inner surface and side surfaces of the glass window wafers to obtain polished glass window wafers, and divide them into an inner surface working area, an outer surface working area, an inner surface optical cementing area, and a side surface optical cementing area according to the functional areas of the polished glass window wafers; S2: Deposit technical index film layers in the inner surface working area, and deposit optical cementing auxiliary films in the inner surface optical cementing area and the side surface optical cementing area. The optical cementing auxiliary films in the optical cementing area need to be polished to remove the diffraction films to obtain secondary polished glass window wafers so as to achieve a better optical cementing effect; S3: The inner surface photo-bonding area of the secondarily polished glass window pane is photo-bonded with the side photo-bonding area of another polished glass window pane to obtain a cuboid glass chamber 1, and a deepening bonding process is carried out to enhance the photo-bonding strength; S4: One end of the flange glass assembly 2 assembled as a whole is photo-bonded to the end face of the glass chamber 1 with the flange blind plate 4, forming a glass vacuum chamber.

[0032] In some embodiments, in S1, the classical polishing method is used to polish the glass window pane to obtain a polished glass window pane, and among the 6 polished glass window panes, the sizes of two opposite polished glass window panes are the same.

[0033] In some embodiments, S3 specifically includes: S301: Take four secondarily polished glass window panes on which the technical guidance film and the photo-bonding auxiliary film have been deposited. The inner surface photo-bonding area of the polished glass window pane is photo-bonded to the side photo-bonding area of another polished glass window pane to obtain a "mouth"-shaped window pane; S302: Carry out a deepening treatment on the "mouth"-shaped window pane to obtain a deepened "mouth"-shaped window pane; S303: Apply a protective paint to the working area of the inner surface of the deepened "mouth"-shaped window pane; after filling the inside of the deepened "mouth"-shaped window pane with abrasive blocks, polish the two end faces of the deepened "mouth"-shaped window pane to obtain the photo-bonding area of the "mouth"-shaped window pane; remove the abrasive blocks and the protective paint in sequence; S304: Deposit a photo-bonding auxiliary film on the photo-bonding area of the "mouth"-shaped window pane; the photo-bonding auxiliary film in the photo-bonding area needs to be polished to remove the diffraction film to achieve a better photo-bonding effect; S305: The photo-bonding areas of the "mouth"-shaped window pane are respectively photo-bonded to and deepened with two other polished glass window panes to obtain a cuboid glass chamber 1.

[0034] In some embodiments, when photo-bonding the four polished glass window panes in S301, the parallelism of two opposite polished glass window panes is <5″, and there are no air bubbles, dirt spots or scratches at the photo-bonding joints, obtaining a "mouth"-shaped window pane.

[0035] In some embodiments, refer to Figure 1 and Figure 2 , for a glass vacuum chamber, its glass chamber 1 is a rectangle of any size composed of 6 window glass panes, and a through hole is provided in the middle of one of the windows for communicating and connecting with the quartz tube of the flange glass assembly. All the working surfaces and photo-bonding surfaces of the 6 window panes are subjected to precision polishing treatment, and corresponding required film layers are deposited. After the film coating is completed, pairwise photo-bonding is carried out in sequence as shown in Figure 2 . It is required that there are no air bubbles, dirt spots, scratches, etc. on the photo-bonding surface.

[0036] In some embodiments, refer toFigure 3 , a glass vacuum chamber, the flange glass assembly 2 of which is composed of a CF vacuum flange 203, a kovar metal tube 202, and a quartz tube 201. To ensure the airtightness of the combination, the CF vacuum flange 203 and the kovar metal tube 202 are welded by continuous argon arc welding. Note that the thermal expansion coefficient of the selected kovar metal tube material should be close to that of the quartz tube 201. The other end of the kovar metal tube 202 and the quartz tube 201 are connected by sintering, and it is required that the sintering surface is smooth, without bubbles and air leakage. The length of the quartz tube 201 can be appropriately cut according to technical requirements.

[0037] In some embodiments, referring to Figure 4 , the glass chamber 1 of Figure 1 and Figure 2 , the flange glass assembly 2 of Figure 3 , the sealing gasket 3, and the flange blind plate 4 are assembled. The optical cementing surface of the quartz tube 201 of the flange glass assembly 2 is optically cemented with the through-hole edge of the opening window of the glass chamber 1. Note that the tube wall of the quartz tube 201 is flush with the hole wall of the opening window of the glass chamber 1, and there are no bubbles, dirt spots, scratches, etc. on the optical cementing surface. A sealing gasket 3 is placed between the bottom knife edge of the flange glass assembly 2 and the bottom knife edge of the flange blind plate 4, and 6 bolts are used to tighten and fix the flange glass assembly 2, the sealing gasket 3, and the flange blind plate 4. Note that the leak detection groove positions of the flange glass assembly 2 and the flange blind plate 4 should be aligned, and the sealing gasket 3 is made of oxygen-free high-conductivity copper softer than the flange material to avoid damaging the flange knife edge.

[0038] In some embodiments, referring to Figure 5 , Figure 6 and Figure 7 , a preparation method of a glass vacuum chamber, comprising the following steps: S1: The glass chamber 1 is composed of 6 glass sheets. Its material is fused quartz. Through grinding and polishing, the surface shape, angle, surface defects, roughness, etc. of the inner surface and the optical cementing surface of 4 glass sheets are processed within the technical requirements range, and the inner and outer surfaces of the other 2 glass sheets are both processed within the technical requirements range. The feature is that the sizes of the 6 glass sheets need to match, the surface shape is better than λ / 20, and the closing relationship of the angles should be ≤0.2″, the surface roughness Ra is better than 1.2 Å, and all surface defects are better than the 10-5 standard of the US military standard MIL-13830A.

[0039] S2: After the inner surface and the optical cementing surface of the 6 glass sheets of the glass chamber are polished, surface film coating is carried out. All optical cementing surfaces are coated with optical cementing auxiliary films, and the inner surface working surfaces are coated with antireflection films.

[0040] S3: After the 6 glass sheets of the glass chamber are coated, they are annealed.

[0041] S4: Remove the diffraction film on the optical bonding area of the six glass sheets, and then perform optical bonding combination on four window sheets with equal lengths. It is required that there are no bubbles, dirt spots, scratches, etc. on the optical bonding surface.

[0042] S5: Perform deep processing on the four-piece glass assembly after the optical bonding combination is completed.

[0043] S6: Protect the working surfaces of the four-piece glass assembly after deep processing is completed, and grind and polish the four outer surfaces and two end faces. The requirements are the same as those in step S1. It should be particularly noted that the parallelism of the two opposite window sheets should be better than 10″, the parallelism of a single window sheet should be better than 1.5″, and the parallelism of the two end faces should be better than 1.5″.

[0044] S7: Coat an antireflection film on the outer surfaces of the four-piece glass assembly, and coat an optical bonding auxiliary film on the two end faces.

[0045] S8: After coating is completed, optically bond the remaining two window sheets to the two end faces. It is required that there are no bubbles, dirt spots, scratches, etc. on the optical bonding surface, and the inner surfaces should be wiped clean before optical bonding, without any dirt or contamination.

[0046] S9: Perform grinding and polishing processing on the quartz tube end face of the flange glass assembly 2. The total height from the end face to the bottom of the flange should meet the technical index size requirements, the surface shape is better than λ / 10, and the defects are better than the 10-5 standard of the US military standard MIL-13830A.

[0047] S10: Coat a single-layer oxidation scale on the working surface of the polished flange glass assembly 2. And process the diffraction film on the working surface.

[0048] S11: Optically bond the working surfaces of the window sheet assembly completed in step S8 and the flange glass assembly 2 completed in step S10. Note that the quartz tube end face of the flange glass assembly is optically bonded to the through-hole edge of the window sheet of the window sheet assembly. It is required that there are no bubbles, dirt spots, scratches, etc. on the optical bonding surface, and the inner surface of the flange glass assembly should be wiped clean before optical bonding, without any dirt or contamination. S12: Perform deep processing on the assembled chamber.

[0049] S13: Place a sealing gasket 3 between the bottom knife edge of the flange of the flange glass assembly 2 and the bottom knife edge of the flange blind plate 4, and tighten it with screws.

[0050] Example: See Figure 1 and Figure 2 , select a glass chamber with a finished inner size of 120mm * 36mm * 36mm, a single-piece wall thickness of 4mm, and a finished outer size of 128mm * 44mm * 44mm for processing.

[0051] The glass chamber 1 is composed of 6 window panes, and a through hole is provided in the middle of one of the window panes. Grind and polish the working surfaces of the 6 window panes, with the requirements: surface shape better than λ / 20, single-sided parallelism better than 1.5″, and defects better than 10 / 5; grind and polish the optical cement surface, with the requirements: surface shape better than λ / 10, single-sided parallelism better than 1.5″, and defects better than 10 / 5 (there should be no scratches in the optical cement area), and the perpendicularity between the optical cement surface and the working surface is better than 1.5″.

[0052] For the 4 window panes on the side of the glass chamber 1, as Figure 2 shown, cement them together in sequence by optical cementing. Note that the angular closure of the perpendicularity between the optical cement area and the working surface of the four window panes should be better than 0.2″, otherwise it is difficult to complete the optical cementing of the four window panes.

[0053] To ensure that the film layer in the working area is not damaged, first process the inner surface working surface and the side optical cement surface, then deposit a film for optical cementing deepening, and then process the outer surface and the end face working surface, and finally deposit a film on the outer surface and perform optical cementing deepening on the end face. Selecting this method of cyclic processing of polishing and coating can ensure that the film layer quality and surface shape accuracy are not damaged and maintain good optical performance.

[0054] To obtain window panes with better surface shape accuracy, the window pane material is selected as fused quartz. To obtain window panes with a surface shape better than λ / 20, different ways of mounting on the plate such as mounting on the plate with sealing wax strips, mounting on the plate with felt, and mounting on the plate with sealing wax balls are selected, and the best method of mounting on the plate has been obtained through experiments.

[0055] Figure 2 As shown, to enable the four window panes to be perfectly optically cemented, the perpendicularity angle tolerance between the side surfaces and the large surfaces of the four window panes should be controlled within 1″, and the four 90° closure angles between the four window panes should be controlled within 0.2″. This requires that after the window panes are optically processed, the closure angles need to be matched first. Those with a closure angle meeting ≤0.2″ are paired as a set, and a set with the closure angle matched is used as the four window panes of a glass chamber for subsequent film deposition and optical cementing deepening.

[0056] After the optical cementing deepening of the four window panes is completed, then optically process the outer surface of the chamber. During processing, to ensure that the film layer on the inner surface is not damaged, apply a uniform layer of protective paint on the inner surface and paste a piece of protective glass with a size matching the inner cavity size of the chamber. When processing the outer surface, first process the 2 end faces. To ensure good optical cementing deepening effect later, the surface shape accuracy of the 2 end faces should meet better than λ / 10, the defects should meet 10 - 5, and there should be no through scratches, and ensure at least a 2 - mm - wide optical cementing tape to ensure the sealing performance of the entire chamber after optical cementing deepening. After the two end faces are processed, apply a uniform layer of protective paint on the surface to protect the working surface from being damaged.

[0057] After the end face machining is completed, machine the four outer surfaces. When machining the inner surfaces, the parallelism of a single window pane has been ensured to be better than 1.5″ and the closing relationship of the four vertical angles ≤ 0.2″. Then, for the four window panes after optical cement deepening as Figure 2 shown, the parallelism of the inner surfaces of the opposite window panes should be within 2″. In this way, to ensure that the parallelism of the outer surfaces of the opposite window panes meets the requirements during the machining of the outer surfaces, it is only necessary to ensure the parallel index in each link when machining the two opposite window panes, and a glass chamber with both the inner and outer surfaces meeting the parallelism requirements can be obtained. When machining the outer surfaces, it is necessary to pay attention to meeting the following requirements: the surface shape is better than λ / 20, the parallelism of the opposite window panes is better than 3″, and the defects are better than 10 / 5.

[0058] After the optical cementing of the outer surfaces is completed, deposit the film layer on the outer surfaces. Finally, perform optical cement deepening on the end faces.

[0059] During optical cement deepening, in order to obtain good deepening effects, through a large number of experiments, starting from aspects such as the treatment of the optical cement area to the temperature process of deepening, the best optical cement deepening plan is finally determined to obtain a complete glass chamber 1 with good deepening effects and high sealing performance.

[0060] To ensure that the film layer quality of the inner and outer surfaces of the glass chamber 1 is not damaged, as Figure 5 shown, the glass chamber 1 and the flange glass assembly 2 are connected by optical cement deepening, which avoids the film layer damage caused by the traditional sintering method and also ensures the sealing performance of the chamber. By machining the glass chamber 1 and the flange glass assembly 2 separately, after they are processed respectively and then combined, it avoids the pollution during the welding and sintering processes of the flange glass assembly 2 itself from entering the chamber 1, resulting in the internal environmental pollution of the chamber 1 and being difficult to clean, and ensures the cleanliness of the internal environment of the chamber 1.

[0061] In some embodiments, the processing method of the window panes of the glass chamber 1 and the optical cement deepening method are as follows: Step 1: Mount the window pane blanks. As Figure 7 shown, use shellac to mount them. Heat the shellac and knead it into small round balls with a diameter of about φ5, and evenly cover the entire mounting surface with the shellac balls. When heating and mounting, no pressure should be applied, and it should be allowed to cool naturally.

[0062] Step 2: Grind and polish the inner surfaces and the optical cement surfaces of the chamber. Pay attention to the polishing time during polishing. Adjust the pressure of the polishing machine to be maintained at about 0.2 bar, and do not apply pressure in the last 8 hours of polishing, allowing the self-weight of the workpiece disk to cooperate with the polishing to ensure that the surface roughness of the polished surface ≤ 1.2 Å, the surface shape accuracy ≤ λ / 20, the defects of the entire surface meet 10 - 5, and the vertical accuracy between the side surface and the large surface ≤ 1.5″.

[0063] Step 3: Deposit films on the working surfaces and the optical cement surfaces. Deposit films on the working surfaces according to technical requirements, and deposit optical cement auxiliary films on the optical cement surfaces to ensure the effects of the subsequent optical cement deepening process.

[0064] Step 4: Photoresist deepening. First, process the diffractive film on the photoresist surface and clean it thoroughly. Wipe the photoresist surface with 0-grade degreased cotton, and perform photoresist as shown in Figure 2 to ensure that there are no bubbles, dirt spots, scratches, etc. on the photoresist surface. Use an angle correction tooling to assist in photoresist during photoresist. The angle correction tooling needs to adjust the position and thickness of the deposited film layer according to the angle of the glass sheet to ensure that the angle of the glass sheet after photoresist can be corrected. After photoresist is completed, adjust the set deepening temperature and time, and put it into the deepening furnace for deepening treatment.

[0065] Step 5: Grind and polish the outer surface and side surface of the chamber. Coat the inner surface of the chamber with protective paint for protection. After drying for at least 24 hours, paste a protective glass block with the same size as the inner size of the chamber, which can not only protect the inner surface but also be used as a grinding companion block. First, grind and polish the two end faces. The surface shape accuracy is required to be better than λ / 10, the defects should meet 10-5, and there are no through scratches, ensuring a photoresist tape with a width of at least 2 mm. After processing is completed, stick protective tape or coat protective paint and dry for 24 hours, and then process the four outer surfaces. The method of mounting on the chuck during outer surface processing refers to Step 1. During the processing, the removal amount of the entire surface remains the same to ensure the parallelism relative to the window piece. The polishing method refers to Step 2. The surface shape is required to be better than λ / 20, the parallelism relative to the window piece is better than 3″, the defects are better than 10 / 5, and the surface roughness of the polished surface is ≤ 1.2 Å. After polishing is completed, take out the protective glass on the inner surface and clean it. After cleaning the polishing powder and protective paint on the inner and outer surfaces, perform the subsequent processes. At the same time, the quartz tube end face of the flange glass assembly 2 can be processed to ensure that the surface shape accuracy is better than λ / 10, the defects should meet 10-5, and there are no through scratches, ensuring a photoresist tape with a width of at least 2 mm.

[0066] Step 6: Coat the outer surface and the end face (photoresist surface), and at the same time coat the quartz tube end face of the processed flange glass assembly 2 with a photoresist auxiliary film. Refer to Steps 3 and 4 for coating and processing, and refer to Figure 5 as shown to perform photoresist and deepening treatment on the glass chamber 1 and the flange glass assembly 2. Thus, the complete glass chamber processing is completed.

[0067] Step 7: Place a sealing gasket 3 between the bottom knife edge of the flange of the flange glass assembly 2 and the bottom knife edge of the flange blind plate 4, and tighten it with screws to ensure that the inside of the chamber is clean, sealed, and not damaged.

[0068] In the early stage of the present invention, through the statistics of a large amount of experimental data, the window panes with different size ratios are processed and the tests of different upper platen methods are carried out to record the relationship between the cooperation of the window pane size ratio and different upper platen methods and the surface shape accuracy of the window pane; through the film layer position and thickness tests of the four-piece window pane angle correction tooling, the final film layer thickness and position that can correct the angle are determined; through using different methods to process the diffraction film before optical cementing and using different temperature-time relationships during deepening, the influence of the diffraction film processing method, deepening temperature and time on the deepening effect is recorded. In order to finally determine the best processing methods for each link such as the size ratio of the window pane blank, the upper platen method, the film layer position and thickness of the angle correction tooling, the diffraction film processing method, the deepening process, etc., to ensure that each index of the completed finished product meets the requirements.

[0069] For example, when testing four randomly combined window panes with the angle closures of the four-piece window panes being 3″, 1″, and 0.2″ respectively, it is found that for the four-piece window panes with an angle closure of 3″, the first three pieces are very easy to be optically cemented together. However, when the fourth window pane needs to be optically cemented with the other two sides simultaneously on both surfaces, it is very difficult to succeed; for the first three pieces of the randomly combined window panes, they are also very easy to be optically cemented together. For the four-piece window panes, the fourth window pane needs to be freely replaced with other window panes until it can be successfully optically cemented, and it cannot be directly successfully optically cemented at one time; when the angle closure is within 0.2″, the four-piece window panes can be more easily optically cemented into the shape as Figure 2 shown. The angle matching closure relationship of the four-piece window panes and the optical cementing effect are as shown in Table 2 below: Table 2 Comparison of the angle matching closure relationship and optical cementing effect of four-piece window panes

[0070] The above process records the comparison of the closure relationships with different angles and the optical cementing effect. Through experimental data, it is found that the smaller the closure relationship of the four-piece window panes, the smoother the optical cementing into the shape as Figure 2 shown. And during the above optical cementing process, an angle correction tooling is used to assist in optical cementing, that is, two polished right-angled glass blocks are first optically cemented into the shape of a "right-angle ruler", and as Figure 8 shown, the side surface of the first glass block and the outer large surface of the second glass block are in the same plane. On this basis, silicon dioxide films with different thicknesses are deposited at different positions of the angle correction tooling in the shape of a "right-angle ruler" formed by combination for adjusting the angle during the optical cementing of the four-piece window panes. For example, when the first window pane and the second window pane are optically cemented, as Figure 2As shown, if the vertical angle of the inner surface of the optical bonding surface of the window pane is measured to be 90° 3 seconds, without adjustment, when the last window pane is optically bonded, since the angular error is fully transmitted to this window pane, there will be a large angular error between the two optical bonding surfaces of the last window pane, making it difficult to smoothly complete the optical bonding. Therefore, when optically bonding the four window panes in the present invention, an angle correction tooling is selected to assist in correcting the vertical angle between the optical bonding surface and the inner surface of each window pane, ensuring that the error of each vertical angle is "0". The corresponding relationship between the position of the film layer plated on the angle correction tooling and the film layer thickness and the correction of the angular error is shown in Table 3 below: Table 3 Corresponding relationship between the position of the film layer plated on the angle correction tooling and the film layer thickness and the correction of the angular error

[0071] It can be seen from the data in the above table that when selecting a window pane with a width of 28 mm for the angle correction tooling-assisted optical bonding test, the thickness of the plated film layer should be controlled at about 400 nm. And when the initial vertical angle error between the optical bonding surface and the inner surface of the window pane is a "+" value, the film layer should be plated at the second coating position 9 as shown in Figure 8 shown. When the initial vertical angle error between the optical bonding surface and the inner surface of the window pane is a "-" value, the film layer should be plated at the first coating position 8 as shown in Figure 8 shown. Only by combining the film layer thickness and the film layer position can the angular error of the window pane be better corrected.

[0072] The present invention aims to solve the problems in the existing glass vacuum chamber processing technology, such as difficult control of the surface shape of thin-sheet window glass, easy damage and pollution of the coated surface after window pane combination, large difficulty in chamber assembly, and difficulty in meeting the assembly accuracy requirements. The present invention provides a glass vacuum chamber with a high vacuum degree and a preparation method thereof. The advantages of the present invention are that by selecting the processing mode of polishing - coating - re-polishing - re-coating and the optical bonding method assisted by the angle correction tooling, the surface shape accuracy and angular accuracy of the glass window pane can be better controlled; secondly, by separately processing the glass chamber and the flange assembly, it is possible to avoid the pollution generated during the welding and burning of the flange assembly in the processing process from damaging the surface of the glass chamber, so that the film layer and surface finish of the chamber window pane are damaged and affect the optical performance and film layer performance; in addition, through optical bonding and deep processing between window panes and between window panes and quartz tubes, it is possible to ensure that the optical performance, geometric dimensions, angles, and film layer quality are not damaged, and at the same time ensure the sealing performance of the chamber and the structural stability.

[0073] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A glass vacuum chamber, characterized in that, It includes a glass chamber (1), and the glass chamber (1) is a cuboid composed of six glass window panes. A through hole is provided in the middle of one glass window pane of the cuboid, and one end of a flange glass assembly (2) is adhesively connected along the axis at the through hole. The other end of the flange glass assembly (2) is connected to a flange blind plate (4), and a sealing gasket (3) is provided between the flange glass assembly (2) and the flange blind plate (4).

2. A glass vacuum chamber according to claim 1, characterized in that, The flange glass assembly (2) includes a quartz tube (201). One end of the quartz tube (201) is adhesively connected to the glass chamber (1), and the other end is connected to a kovar metal tube (202). The kovar metal tube (202) is connected to a CF vacuum flange (203), and the CF vacuum flange (203) is connected to the flange blind plate (4).

3. A glass vacuum chamber according to claim 2, characterized in that, One end of the kovar metal tube (202) is connected to the CF vacuum flange (203) by continuous argon arc welding, and the other end is connected to the quartz tube (201) by burning and cutting.

4. A glass vacuum chamber according to claim 2, characterized in that, The CF vacuum flange (203) and the flange blind plate (4) are connected by bolts. Six bolt holes are provided on both the CF vacuum flange (203) and the flange blind plate (4). Leak detection grooves are provided on the contact surfaces of the CF vacuum flange (203) and the flange blind plate (4), and the sealing gasket (3) is installed at the leak detection grooves.

5. A glass vacuum chamber according to claim 1, wherein, In the glass chamber (1), the vertical angle between each glass window pane is ≤1″, the surface roughness Ra is not greater than 1.2 Å, and the surface figure is not greater than λ / 20.

6. A glass vacuum chamber according to claim 1, characterized in that, In the glass chamber (1), the material of the sealing gasket (3) is oxygen-free high-conductivity copper.

7. A manufacturing method of the glass vacuum chamber according to any one of claims 1 to 6, characterized in that, It includes: S1: Assemble the flange glass assembly (2) and the flange blind plate (4) into one unit for standby. Optically process the inner surface and side surfaces of the glass window panes to obtain polished glass window panes, and divide them into an inner surface working area, an outer surface working area, an inner surface adhesive area, and a side surface adhesive area according to the functional areas of the polished glass window panes; S2: Deposit technical index film layers on the inner surface working area and the outer surface working area, and deposit adhesive auxiliary films on the inner surface adhesive area and the side surface adhesive area; Polish the adhesive auxiliary films in the adhesive areas to remove the diffraction films to obtain secondary polished glass window panes; S3: The inner surface adhesive area of the secondary polished glass window pane is adhesively bonded with the side surface adhesive area of another polished glass window pane to obtain the cuboid glass chamber (1), and deep bonding is carried out; S4: Connect one end of the flange glass assembly (2) of the flange glass assembly (2) assembled into one unit with the flange blind plate (4) adhesively to the end face of the glass chamber (1) to form a glass vacuum chamber.

8. A manufacturing method of a glass vacuum chamber according to claim 7, characterized in that, In S1, the classical polishing method is used to polish the glass window panes to obtain polished glass window panes, and among the 6 polished glass window panes, the sizes of two opposite polished glass window panes are the same.

9. The manufacturing method of a glass vacuum chamber according to claim 7, characterized in that, The specific content of S3 includes: S301: Take four secondary polished glass window panes on which the technical index film layers and the adhesive auxiliary films are deposited. The inner surface adhesive area of the polished glass window pane is adhesively bonded with the side surface adhesive area of another polished glass window pane to obtain a "mouth"-shaped window pane; S302: Carry out deep processing on the "mouth"-shaped window pane to obtain a deep "mouth"-shaped window pane; S303: Apply protective paint to the working area of the inner surface of the deepened "mouth"-shaped window pane; after filling the inside of the deepened "mouth"-shaped window pane with grinding aids, polish the two end faces of the deepened "mouth"-shaped window pane to obtain the optical cementing area of the "mouth"-shaped window pane; remove the grinding aids and protective paint in sequence; S304: Deposit an optical cementing auxiliary film on the optical cementing areas of the two end faces of the "mouth"-shaped window pane; polish the optical cementing auxiliary film to remove the diffraction film; S305: Deepen the optical cementing areas of the "mouth"-shaped window pane by optically cementing them to two other polished glass window panes respectively to obtain a cuboid glass chamber (1).

10. The manufacturing method of a glass vacuum chamber according to claim 9, characterized in that, In the optical cementing of the four polished glass window panes in S301, the parallelism of the two opposite polished glass window panes is < 5″, and there are no air bubbles, dirt spots or scratches at the optical cementing joints, thus obtaining the "mouth"-shaped window pane.

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