Ultralow-stress ultrahigh-vacuum optical reference cavity

Abstract

The invention provides an ultra-low-stress ultra-high-vacuum optical reference cavity, and relates to the technical field of ultra-stable cavity systems, the ultra-low-stress ultra-high-vacuum optical reference cavity comprises a reference cavity base body, a reflector, a getter assembly and a vacuumizing sealing assembly, a resonance channel is arranged in the reference cavity base body, and the resonance channel comprises a first resonance channel and a second resonance channel which are arranged in a crossed mode; the first resonance channel and the second resonance channel both penetrate through the reference cavity base body, the two ports of the first resonance channel are each provided with a reflecting mirror, the getter assembly is arranged at the first port of the second resonance channel, and the vacuumizing sealing assembly is arranged at the second port of the second resonance channel. The getter assembly is used for adsorbing gas permeating into the resonance channel and maintaining the ultrahigh vacuum degree in the resonance channel. And the vacuumizing sealing assembly is used for vacuumizing the resonant channel. The interior of the optical reference cavity becomes a closed space, long-term ultrahigh vacuum degree can be realized by the optical reference cavity, an external vacuum system environment is not needed any more, and the reflecting mirror is not polluted by the external environment any more.

Description

Technical Field

[0001] This invention relates to the field of ultra-stable cavity system technology, specifically to an ultra-low stress ultra-high vacuum optical reference cavity. Background Technology

[0002] At the forefront of time measurement, gravitational wave detection, navigation and positioning, and even verifying the fundamental physical laws of the universe, scientists' pursuit of "frequency stability" is endless. "Ultra-stable cavities," as a novel optical reference system, are moving from top-tier laboratories to a wider range of applications. With their unique physical design and revolutionary stability, they are setting new benchmarks for next-generation atomic clocks, ultra-stable lasers, and even fundamental physics experiments, becoming the "stabilizing force" supporting the edifice of quantum precision measurement science.

[0003] The core of the ultra-stable cavity system is a high-precision optical reference cavity. The role of the reference cavity is to "lock" the frequency of the laser, reducing its fluctuations to an extremely low level, providing a near-static frequency scale for precision measurements. As the heart of the optical clock, the ultra-stable laser provided by the optical reference cavity is the future standard for defining the "second," with an accuracy hundreds of times higher than that of current microwave atomic clocks, and is expected to redefine the time reference.

[0004] The core function of an optical reference cavity is to maintain a constant physical length. To maintain this constant physical length, it must be manufactured using materials with extremely low coefficients of thermal expansion. Furthermore, to further isolate the optical reference cavity from environmental disturbances, it must be placed in a vacuum environment and, together with a temperature control system, form a controlled "microclimate."

[0005] The surfaces of the mirrors in an optical reference cavity are extremely sensitive to contamination. Even particles a few nanometers in size adhering to the mirror surface can increase light scattering loss by the order of ppm. A contamination layer a few nanometers thick, such as a hydrocarbon contamination layer, can also increase light absorption loss by the order of ppm.

[0006] Typically, optical reference cavities are machined with dedicated vents. These cavities are housed within a vacuum maintenance system, which expels the gas inside. When the optical reference cavity is placed in an ultra-stable cavity system and a vacuum is evacuated, the initial gas turbulence during evacuation carries nano- and micron-sized particles adsorbed on the inner walls of the vacuum system and the surfaces of various complex internal support structures, thus contaminating the mirrors. These particles, once attached to the mirror surfaces, drastically increase light scattering loss, reducing precision. Furthermore, during long-term operation, residual hydrocarbons within the ultra-stable vacuum system continuously volatilize. These volatile contaminants deposit on the surface of the reference cavity mirrors, forming a contamination layer that drastically increases light absorption loss, further reducing precision and ultimately degrading the performance of the optical reference cavity. Summary of the Invention

[0007] The purpose of this invention is to provide an ultra-low stress ultra-high vacuum optical reference cavity, which effectively solves the problem that traditional optical reference cavities are not sealed and that the mirrors in ultra-stable cavity systems are easily contaminated, leading to a decrease in the performance of the optical reference cavity.

[0008] To address the aforementioned problems, this invention discloses an ultra-low stress ultra-high vacuum optical reference cavity, comprising a reference cavity substrate, a mirror, a getter assembly, and a vacuum sealing assembly;

[0009] The reference cavity substrate is provided with a resonant channel, which includes a first resonant channel and a second resonant channel that are arranged in a cross manner. Both the first resonant channel and the second resonant channel penetrate the reference cavity substrate. A reflector is provided at each of the two ends of the first resonant channel. The getter assembly is provided at the first end of the second resonant channel, and the vacuum sealing assembly is provided at the second end of the second resonant channel.

[0010] The getter assembly includes a flexible getter base and a getter body. The flexible getter base is fixedly connected to the reference cavity substrate and seals the first port of the second resonant channel.

[0011] A sealed receiving cavity is formed between the flexible base of the getter and the reference cavity substrate, and the getter body is disposed on the flexible base of the getter and placed in the receiving cavity;

[0012] The getter flexible base includes a getter base body and a getter mounting seat. The getter base body is fixedly connected to the reference cavity base. The getter body is disposed on the getter mounting seat. The getter base body and the getter mounting seat are flexibly connected by a thin-walled structure.

[0013] The vacuum sealing assembly includes a flexible base for the sealing element and a vacuum sealing element. The flexible base for the sealing element includes a base body for the sealing element and a mounting seat for the sealing element. The base body for the sealing element is fixedly connected to the reference cavity substrate. The vacuum sealing element is mounted on the mounting seat for the sealing element. The mounting seat for the sealing element and the base body for the sealing element are flexibly connected through a thin-walled structure.

[0014] Optionally, the sealing element mounting base is provided with a connection hole, the connection hole is connected to the second port of the reference cavity base, the air extraction seal is fixedly sealed on the sealing element mounting base, and the air extraction seal is provided with an air extraction hole that communicates with the connection hole.

[0015] Optionally, the air extraction seal includes a mounting base and an air extraction nozzle. The air extraction nozzle is disposed on one side of the mounting base. The air extraction hole penetrates the mounting base and the air extraction nozzle axially, with one end opening located at the end of the air extraction nozzle and the other end opening located on the mounting base.

[0016] Optionally, the sealing element base body is a hollow outer frame structure, and the sealing element mounting seat is disposed within the hollow cavity of the outer frame structure; the sealing element mounting seat includes a side wall and a base, the base is fixedly and airtightly connected to the mounting chassis of the vacuum seal, and the base is provided with the connection hole; there is an annular gap between the side wall of the sealing element mounting seat and the inner wall of the hollow cavity of the outer frame structure, one end of the side wall is connected to the base, and the other end extends radially outward and is connected to the end face of the sealing element base body through the thin-walled structure; the side wall of the sealing element mounting seat is a thin-walled structure.

[0017] Optionally, the getter body includes an annular receiving shell, the surface of which is provided with an annular groove, and the bottom of which is uniformly covered with a gettering active material;

[0018] The annular groove opening faces the axial direction of the annular receiving housing and towards the first port of the second resonant channel, and the annular receiving housing is disposed on the getter mounting base.

[0019] Optionally, the getter mounting base includes a side plate and a bottom plate. One end of the side plate is flexibly connected to the thin-walled structure of the getter base body, and the other end of the side plate is connected to the bottom plate. A fixing post is provided on the bottom plate, and the fixing post extends toward the first port of the second resonant channel. The annular receiving shell is disposed on the fixing post. The bottom plate of the getter mounting base is a thin-walled structure.

[0020] The side plate, bottom plate, getter base body, and reference cavity base of the getter mounting seat together form the receiving cavity.

[0021] Optionally, the getter assembly further includes a retaining spring, which is a cylindrical structure. One end of the retaining spring is fixed to the fixing post, and the other end is fixed to the annular receiving shell. The inner diameter of the retaining spring is larger than the outer diameter of the fixing post, and the inner diameter of the annular receiving shell is larger than the outer diameter of the fixing post. Both the retaining spring and the annular receiving shell are sleeved on the fixing post.

[0022] Optionally, the thickness of the thin-walled structure is between 0.2 mm and 0.8 mm.

[0023] Optionally, the getter base body and the getter mounting seat are integrally formed; the seal base body and the seal mounting seat are integrally formed.

[0024] Optionally, the reference cavity substrate is a cube structure, cuboid structure, cylindrical structure, olive-shaped structure, or spherical structure, and the first resonant channel and the second resonant channel are arranged perpendicular to each other, with the intersection of the first resonant channel and the second resonant channel located at the center of the reference cavity substrate.

[0025] Beneficial effects:

[0026] This invention provides an ultra-low stress, ultra-high vacuum optical reference cavity. By directly mounting a getter assembly and a vacuum sealing assembly onto the reference cavity substrate, the interior of the optical reference cavity becomes a sealed space. The optical reference cavity itself can achieve long-term ultra-high vacuum tightness and self-sustaining vacuum maintenance, eliminating the need for an external vacuum system environment and preventing contamination of the reflector by the external environment. Simultaneously, both the getter assembly and the vacuum sealing assembly employ thin-walled, flexible connections, effectively preventing the transmission of assembly stress, clamping stress, and welding stress to the reference cavity substrate, thus achieving ultra-low stress in the optical reference cavity. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the optical reference cavity disclosed in this application; Figure 2 This is a schematic diagram of the getter component structure disclosed in this application; Figure 3 This is a schematic diagram of the main structure of the getter disclosed in this invention, wherein a is a top view and b is a cross-sectional view; Figure 4 This is a schematic diagram of the flexible getter base structure disclosed in this invention; Figure 5 This is a schematic diagram of the vacuum sealing assembly structure disclosed in this invention; Figure 6 This is a schematic diagram of the flexible base structure of the sealing element disclosed in this invention, wherein a is a cross-sectional view and b is a top view; Figure 7 This is a schematic diagram of the air extraction sealing component structure disclosed in this invention, wherein a is a top view and b is a cross-sectional view; Figure 8 This is a schematic diagram of the reference cavity substrate structure of the square structure disclosed in this invention; Figure 9This is a schematic diagram of the reference cavity substrate structure with a rectangular structure disclosed in this invention; Figure 10 This is a schematic diagram of the reference cavity substrate structure of the cylindrical structure disclosed in this invention; Figure 11 This is a schematic diagram of the reference cavity substrate structure of the spherical structure disclosed in this invention; Figure 12 This is a schematic diagram of the reference cavity substrate structure of the olive-shaped structure disclosed in this invention.

[0028] Explanation of reference numerals in the attached figures: 1. Reference cavity substrate; 11. First resonant channel; 12. Second resonant channel; 121. First port; 122. Second port; 2. Reflector; 3. Getter assembly; 31. Getter flexible base; 311. Getter base body; 312. Getter mounting seat; 313. Fixing post; 32. Getter body; 321. Annular receiving shell; 322. Getter active material; 33. Receiving cavity; 34. Snap ring; 4. Vacuum sealing assembly; 41. Sealing element flexible base; 411. Sealing element base body; 412. Sealing element mounting seat; 413. Connecting hole; 42. Vacuum sealing element; 421. Vacuum port; 422. Mounting chassis; 423. Vacuum nozzle. Detailed Implementation

[0029] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] The technical solution of the present invention will be further illustrated below through specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The content of the embodiments does not constitute a limitation on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figures 1-12 As shown, this invention discloses an ultra-low stress ultra-high vacuum optical reference cavity, which enables the reference cavity to be independently sealed in ultra-high vacuum and maintain a constant vacuum level for decades. Specifically, it includes a reference cavity substrate 1, a reflector 2, a getter assembly 3, and a vacuum sealing assembly 4.

[0033] The reference cavity substrate 1 contains a resonant channel, which includes a first resonant channel 11 and a second resonant channel 12 that are interconnected. Both the first resonant channel 11 and the second resonant channel 12 penetrate the reference cavity substrate 1. A reflector 2 is installed at each of the two ends of the first resonant channel 11, with the surfaces of the reflectors 2 facing inwards towards the first resonant channel 11 to form the main optical resonant channel. The two reflectors 2 are connected to the reference cavity substrate 1 by van der Waals forces. The reflectors 2 are made of a material with low thermal deformation and low thermal noise, exhibiting low optical loss.

[0034] The getter assembly 3 is located at the first port 121 of the second resonant channel 12. After the vacuum is completed, the getter assembly 3 continuously adsorbs the residual gas and micro-leaking gas in the resonant channel, maintains the ultra-high vacuum level in the resonant channel for a long time, and does not require an external vacuum maintenance system, thereby improving the integration and independence of the reference cavity.

[0035] The vacuum sealing assembly 4 is located at the second port 122 of the second resonant channel 12. The vacuum sealing assembly 4 is used to connect to an external vacuum pump. After assembly, the resonant channel is evacuated. Once the vacuum reaches the standard, a permanent seal is achieved, preventing external gas from entering and ensuring the long-term stability of the vacuum environment inside the reference cavity.

[0036] Furthermore, such as Figure 2 As shown, the getter assembly 3 includes a getter flexible base 31 and a getter body 32. The getter flexible base 31 is fixedly connected to the reference cavity substrate 1 and seals the first port 121 of the second resonant channel 12. The connection method can be van der Waals force bonding, low temperature and low stress bonding, etc., to avoid rigid connection causing assembly stress.

[0037] A sealed receiving cavity 33 is formed between the flexible getter base 31 and the reference cavity substrate 1. The getter body 32 is disposed on the flexible getter base 31 and placed in the receiving cavity 33. This ensures that the getter body 32 can fully exert its adsorption function while avoiding direct contact and compression of the reference cavity by the getter body 32.

[0038] The getter flexible base 31 is made of the same material as the reference cavity substrate 1, or is made of a material with a low coefficient of expansion, such as special alloys, ceramics, or microcrystalline glass. This eliminates the thermal stress caused by thermal expansion in the getter flexible base 31.

[0039] like Figure 4 As shown, the getter flexible base 31 includes a getter base body 311 and a getter mounting seat 312. The getter base body 311 is fixedly connected to the reference cavity substrate 1, and the getter body 32 is disposed on the getter mounting seat 312. The getter base body 311 and the getter mounting seat 312 are flexibly connected by a thin-walled structure. The thin-walled structure can absorb and disperse assembly stress, clamping stress, and thermal stress through its own minute deformation, blocking the transmission of stress to the reference cavity substrate 1, ensuring that the reference cavity substrate 1 is stress-free and deformation-free.

[0040] Furthermore, such as Figure 5 As shown, the vacuum sealing assembly 4 includes a flexible base 41 for the sealing element and a vacuum sealing element 42, wherein the vacuum sealing element 42 is preferably made of 4J32 alloy. 4J32 alloy has a density of less than 5 × 10⁻⁶. -7 An ultra-low coefficient of linear expansion of / ℃. In other embodiments, the vacuum seal 42 may also be made of quartz glass.

[0041] The flexible base 41 of the sealing element is made of the same material as the reference cavity substrate 1, or is made of a material with a low coefficient of expansion, such as special alloys, ceramics, or microcrystalline glass, thereby eliminating thermal stress caused by thermal expansion in the flexible base 41 of the sealing element. The flexible base 41 of the sealing element is fixedly and sealed to the reference cavity substrate 1, and the connection method can be van der Waals force bonding or indium welding.

[0042] Due to its extremely high flexibility and plasticity, indium can isolate most of the thermal stress caused by the mismatch in the coefficients of linear expansion of materials. Through a special hot-pressing process, indium can be tightly bonded to the surface of most materials, including metals, ceramics, and glass, achieving an airtight connection.

[0043] like Figure 6 As shown, the flexible base 41 for the sealing element includes a base body 411 and a mounting seat 412 for the sealing element, and the vacuum seal 42 is mounted on the mounting seat 412. The mounting seat 412 and the base body 411 are flexibly connected by a thin-walled structure.

[0044] This application achieves a sealed optical reference cavity by directly mounting the getter assembly 3 and the vacuum sealing assembly 4 onto the reference cavity substrate 1. This allows the optical reference cavity to maintain a long-term, ultra-high vacuum and self-sustaining vacuum, eliminating the need for an external vacuum system and preventing contamination of the reflector 2 by the external environment. By incorporating thin-walled flexible connection structures on both the vacuum sealing assembly 4 and the getter assembly 3, the assembly and clamping stresses of the getter assembly 3 are prevented from being transferred to the reference cavity substrate 1. Simultaneously, welding and thermal stresses from the vacuum sealing assembly are also prevented from being transferred to the reference cavity substrate 1. This results in ultra-low stress in the optical reference cavity, avoiding any impact on it and achieving complete stress isolation. It completely eliminates the negative impacts of assembly, welding, and thermal mismatch on the structural accuracy and optical resonance performance of the reference cavity substrate 1, ensuring the optical reference cavity can maintain a high level of vacuum for an extended period. -6 The ultra-high vacuum state of Pa remains unchanged for decades.

[0045] Specifically, such as Figure 6 As shown, the sealing element mounting base 412 is provided with a connecting hole 413, which communicates with the second port 122 of the reference cavity substrate 1. The vacuum sealing element 42 is fixedly sealed on the sealing element mounting base 412, and the vacuum sealing element 42 is provided with a vacuum port 421 communicating with the connecting hole 413. During vacuuming, an external vacuum pump evacuates the resonant channel through the vacuum port 421. After reaching the preset ultra-high vacuum level, the vacuum port 421 is permanently sealed, thereby forming a closed, stable, and long-lasting ultra-high vacuum environment inside the resonant channel.

[0046] Specifically, such as Figure 7 As shown, the vacuum sealing component 42 includes a mounting base 422 and a vacuum nozzle 423. The mounting base 422 has a disc-shaped structure, and the vacuum nozzle 423 has a cylindrical structure. The vacuum nozzle 423 is coaxially disposed on one side of the mounting base 422. The vacuum hole 421 coaxially penetrates the mounting base 422 and the vacuum nozzle 423 along the axial direction. One end of the hole is located at the end of the vacuum nozzle 423 for connecting to a vacuum pump, and the other end is located on the mounting base 422 for communicating with the connection hole 413.

[0047] Furthermore, the sealing element base body 411 has a hollow outer frame structure, and a sealing element mounting seat 412 is disposed within the hollow cavity of the outer frame structure. The sealing element mounting seat 412 includes a side wall and a base. The base is fixedly and airtightly connected to the mounting base 422 of the vacuum seal 42, and a connection hole 413 is provided on the base. There is an annular gap between the side wall of the sealing element mounting seat 412 and the inner wall of the hollow cavity of the outer frame structure, providing space for minor deformation of the sealing element mounting seat 412. One end of the side wall is connected to the base, and the other end extends radially outward and is integrally connected to the end face of the sealing element base body 411 through a thin-walled structure to form an annular flexible support.

[0048] Preferably, the hollow outer frame structure of the sealing base body 411 and the sealing mounting base 412 are integrally processed and formed without splicing or welding, so as to ensure structural consistency and avoid additional stress caused by the split structure.

[0049] Preferably, the mounting base 422 of the vacuum seal 42 and the base of the seal mounting seat 412 are welded together by indium sealing to meet the requirements of the reference cavity for sealing performance and low stress.

[0050] Preferably, the sidewall of the seal mounting base 412 is also a thin-walled structure to ensure that the flexible base 41 of the seal has sufficient flexibility.

[0051] Furthermore, the thickness of the sidewall of the sealing element mounting base 412 and the thin-wall structure between the sidewall and the sealing element base body 411 is 0.2mm-0.8mm, so as to achieve stress buffering and stress absorption while ensuring structural strength and sealing rigidity. Too little thickness will easily lead to insufficient structural strength, while too much thickness will reduce the effect of stress buffering and absorption.

[0052] Specifically, such as Figure 3 As shown, the getter body 32 includes an annular receiving shell 321. An annular groove is provided on the surface of the annular receiving shell 321, and a getter active material 322 is uniformly distributed at the bottom of the annular groove. The getter active material 322 is typically a zirconium-aluminum getter or a barium-containing getter. The opening of the annular groove faces the axial direction of the annular receiving shell 321 and towards the first port 121 of the second resonant channel 12, allowing the getter active material 322 to contact the gas within the resonant channel and ensuring the adsorption efficiency of the getter active material 322. The annular receiving shell 321 is mounted on the getter mounting base 312.

[0053] Specifically, such as Figure 4 As shown, the getter mounting base 312 includes a side plate and a bottom plate. One end of the side plate is flexibly connected to the thin-walled structure of the getter base body 311, and the other end of the side plate is connected to the bottom plate. A fixing post 313 is provided on the bottom plate, and the fixing post 313 extends toward the first port 121 of the second resonant channel 12. An annular receiving shell 321 is disposed on the fixing post 313.

[0054] Furthermore, such as Figure 2As shown, the getter assembly 3 also includes a retaining spring 34, which is a cylindrical structure. One end of the retaining spring 34 is fixed to the fixing post 313, and the other end is fixed to the annular receiving housing 321. The inner diameter of the retaining spring 34 is larger than the outer diameter of the fixing post 313, and the inner diameter of the annular receiving housing 321 is larger than the outer diameter of the fixing post 313. Both the retaining spring 34 and the annular receiving housing 321 are sleeved on the fixing post 313. The retaining spring 34 achieves elastic clamping of the annular receiving housing 321. Elastic clamping generates no stress, avoiding the stress generated by rigid compression.

[0055] The side plate, bottom plate, getter base body 311, and reference cavity base 1 of the getter mounting seat 312 together form a receiving cavity 33, providing a closed working space for the getter body 32 to fully absorb air.

[0056] Preferably, the base plate of the getter mounting base 312 is also a thin-walled structure to ensure that the flexible base 31 of the getter has sufficient flexibility.

[0057] The thickness of the thin-walled structure is 0.2mm-0.8mm, which, together with the thin-walled structure of the vacuum sealing component 4, achieves a symmetrical and balanced stress decoupling effect.

[0058] Preferred, such as Figures 8-12 As shown, the reference cavity substrate 1 can be selected from cubic, cuboid, cylindrical, olive-shaped, or spherical structures depending on the application scenario. The first resonant channel 11 and the second resonant channel 12 are arranged perpendicularly to each other, and the intersection point of the first resonant channel 11 and the second resonant channel 12 is located at the center of the reference cavity substrate 1. After the reference cavity substrate 1 is processed, it can be assembled with the reflector 2, the getter assembly 3, and the vacuum sealing assembly 4 after chemical cleaning and vacuum degassing.

[0059] In practical implementation, after the optical reference cavity is assembled, helium mass spectrometry is performed to ensure that the leakage rate of the optical reference cavity is less than 5 × 10⁻⁶. -11 Pa˙m 3 / s, then activate the getter, and finally seal the extraction seal 42. The sealing method can be to clamp the sealing extraction nozzle 423. When the extraction seal 42 is made of quartz glass, the extraction nozzle 423 can also be melted off by flame.

[0060] Because the optical reference cavity is highly airtight, no external contaminants can contaminate mirror 2 during subsequent higher-level assembly and use. Therefore, the optical reference cavity can always maintain optimal condition, and the vacuum level inside the optical reference cavity can be maintained at 10 for decades. -6 The precision is in the Pa range and can remain unchanged for decades.

[0061] The applicant declares that the above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. An ultra-low stress, ultra-high vacuum optical reference cavity, characterized in that, It includes a reference cavity substrate (1), a reflector (2), a getter assembly (3), and a vacuum sealing assembly (4); The reference cavity substrate (1) is provided with a resonant channel, which includes a first resonant channel (11) and a second resonant channel (12) arranged in a cross manner. Both the first resonant channel (11) and the second resonant channel (12) penetrate the reference cavity substrate (1). A reflector (2) is provided at each of the two ports of the first resonant channel (11). The getter assembly (3) is provided at the first port (121) of the second resonant channel (12). The vacuum sealing assembly (4) is provided at the second port (122) of the second resonant channel (12). The getter assembly (3) includes a getter flexible base (31) and a getter body (32). The getter flexible base (31) is fixedly connected to the reference cavity substrate (1) and seals the first port (121) of the second resonant channel (12). The getter flexible base (31) and the reference cavity base (1) together form a closed receiving cavity (33), and the getter body (32) is disposed on the getter flexible base (31) and placed in the receiving cavity (33); The getter flexible base (31) includes a getter base body (311) and a getter mounting seat (312). The getter base body (311) is fixedly connected to the reference cavity base (1). The getter body (32) is disposed on the getter mounting seat (312). The getter base body (311) and the getter mounting seat (312) are flexibly connected by a thin-walled structure. The vacuum sealing assembly (4) includes a flexible sealing base (41) and a vacuum sealing element (42). The flexible sealing base (41) includes a sealing base body (411) and a sealing mounting seat (412). The sealing base body (411) is fixedly connected to the reference cavity base (1). The vacuum sealing element (42) is mounted on the sealing mounting seat (412). The sealing mounting seat (412) and the sealing base body (411) are flexibly connected through a thin-walled structure.

2. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 1, characterized in that, The sealing element mounting base (412) is provided with a connection hole (413), which is connected to the second port (122) of the reference cavity base (1). The air extraction sealing element (42) is fixedly sealed on the sealing element mounting base (412), and the air extraction sealing element (42) is provided with an air extraction hole (421) that is connected to the connection hole (413).

3. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 2, characterized in that, The air extraction seal (42) includes a mounting base (422) and an air extraction nozzle (423). The air extraction nozzle (423) is disposed on one side of the mounting base (422). The air extraction hole (421) passes through the mounting base (422) and the air extraction nozzle (423) axially, with one end opening located at the end of the air extraction nozzle (423) and the other end opening located on the mounting base (422).

4. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 3, characterized in that, The sealing base body (411) is a hollow outer frame structure, and the sealing mounting seat (412) is disposed in the hollow cavity of the outer frame structure; the sealing mounting seat (412) includes a side wall and a base, the base is fixedly and airtightly connected to the mounting base (422) of the vacuum sealing element (42), and the base is provided with the connection hole (413); there is an annular gap between the side wall of the sealing mounting seat (412) and the inner wall of the hollow cavity of the outer frame structure, one end of the side wall is connected to the base, and the other end extends radially outward and is connected to the end face of the sealing base body (411) through the thin-wall structure; the side wall of the sealing mounting seat (412) is a thin-wall structure.

5. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 1, characterized in that, The getter body (32) includes an annular housing (321), the surface of which is provided with an annular groove, and the bottom of which is uniformly covered with a gettering active material (322). The opening of the annular groove faces the axial direction of the annular housing (321) and the first port (121) of the second resonant channel (12). The annular housing (321) is disposed on the getter mounting base (312).

6. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 5, characterized in that, The getter mounting base (312) includes a side plate and a bottom plate. One end of the side plate is flexibly connected to the thin-walled structure of the getter base body (311), and the other end of the side plate is connected to the bottom plate. A fixing post (313) is provided on the bottom plate. The fixing post (313) extends toward the first port (121) of the second resonant channel (12). The annular receiving shell (321) is disposed on the fixing post (313). The bottom plate of the getter mounting base (312) is a thin-walled structure. The side plate, the bottom plate, the getter base body (311), and the reference cavity base (1) of the getter mounting base (312) together form the receiving cavity (33).

7. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 6, characterized in that, The getter assembly (3) also includes a retaining ring (34), which is a cylindrical structure. One end of the retaining ring (34) is fixed to the fixing post (313), and the other end is fixed to the annular receiving shell (321). The inner diameter of the retaining ring (34) is larger than the outer diameter of the fixing post (313), and the inner diameter of the annular receiving shell (321) is larger than the outer diameter of the fixing post (313). Both the retaining ring (34) and the annular receiving shell (321) are sleeved on the fixing post (313).

8. An ultra-low stress ultra-high vacuum optical reference cavity according to any one of claims 1-7, characterized in that, The thickness of the thin-walled structure is between 0.2 mm and 0.8 mm.

9. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 1, characterized in that, The getter base body (311) and the getter mounting seat (312) are integrally formed; the seal base body (411) and the seal mounting seat (412) are integrally formed.

10. The ultra-low stress ultra-high vacuum optical reference cavity according to claim 1, characterized in that, The reference cavity substrate (1) is a cube structure, cuboid structure, cylindrical structure, olive-shaped structure or spherical structure. The first resonant channel (11) and the second resonant channel (12) are arranged perpendicularly to each other, and the intersection of the first resonant channel (11) and the second resonant channel (12) is located at the center of the reference cavity substrate (1).

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