Optical thermostat with comprehensive vibration reduction and low-temperature in-situ displacement functions

Abstract

The invention discloses an optical thermostat with comprehensive vibration reduction and low-temperature in-situ displacement functions, which adopts upper and lower opposite vibration absorbers and a large-mass base to realize first-order to second-order inertial vibration absorption, and further realizes thorough decoupling with an optical platform in a suspension type non-contact manner, and the vibration transmissibility can be reduced to be less than 10%. Resonant frequencies of two systems (a sample table system and a cold head system) are designed to achieve vibration decoupling. The technical problems that in the prior art, the high-grade vibration isolation capacity is insufficient, refrigerator noise is easily coupled to a measuring light path, the low-temperature in-situ precision displacement capacity is lacked, and the contradiction between heat isolation, convenience and cost is difficult to balance can be solved. Under the support of a conventional GM refrigerator, the comprehensive requirements of ultralow basic vibration, strong decoupling of a measurement light path, low-temperature in-situ micron-sized displacement, convenient sample replacement and efficient refrigeration / thermal control are met at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-temperature scientific experimental instruments, in particular to an optical thermostat with comprehensive vibration reduction and low-temperature in-situ displacement functions. BACKGROUND

[0002] The low-temperature optical thermostat is a core device for frontier experiments such as quantum computing, single-photon detection, and low-temperature spectral microscopy.

[0003] The common low-temperature optical thermostats on the market (such as products of Janis Research Company, USA, and Montana Instruments Company, USA) usually adopt rigid or semi-rigid structure to connect the refrigerator and the sample stage, and some adopt a multi-stage suspension scheme (such as some products of Oxford, UK), which is often complex and heavy in structure, inconvenient to maintain and replace samples, and often faces challenges in displacement stage integration and stability.

[0004] Internationally, the low-vibration technology for closed-cycle optical thermostats mainly focuses on off-axis arrangement, opposed bellows, spring damping suspension, flexible heat chain / heat tape, and layered insulation structure. For example, US9303914B2 / US8746008B1 proposes to arrange the cold head off-axis and realize sealing and vibration reduction by using opposed bellows + spring damping; US8756941B2 realizes thermal-mechanical decoupling by using sleeve type insulation structure + heat link; CN107655236B uses flexible pipe + vibration damping heat dissipation sheet to reduce the vibration of the sample stage; EP2597041A1 discloses the application of flexible heat tape in “high thermal conductivity-low rigidity”. Although the above technologies can reduce some vibrations, they are still difficult to meet the comprehensive needs of whole-machine level isolation, low-temperature in-situ micro-displacement, and quick sample replacement.

[0005] The above schemes improve the vibration isolation and thermal insulation performance to some extent, but still have the following limitations: Insufficient vibration reduction: existing schemes (such as single flexible heat chain and simple bellows support) are difficult to efficiently suppress wideband (especially low-frequency) vibration, especially when rigidly or semi-rigidly coupled with the refrigerator, the residual vibration is still high (>micron level), which is not enough to support the sub-micron vibration demand of quantum precision experiments; Insufficient rigidity connection or isolation: some designs (such as CN220507416U) directly rigidly connect the sample platform and the optical measurement platform, or only use the base for insufficient isolation, which causes the refrigerator noise to easily couple to the external sensitive detection light path; Weak in-situ displacement capability: common thermostats are limited by thermal conductivity and vibration reduction structure, or lack effective design, making it difficult to maintain an ultra-low temperature environment (such as below 10K) while accurately (micron level) and stably adjusting the sample in-situ in multiple dimensions; Convenience and thermal control conflict / cost is high: in order to achieve good thermal isolation, the multi-layer heat shield structure is complex and difficult to disassemble, which increases the difficulty and time of replacing the sample (affecting convenience); while the simplified thermal structure in pursuit of convenience has higher thermal load and lower refrigeration efficiency (especially when using a conventional GM refrigerator, the contradiction is more prominent). Highly optimized low-vibration design (such as complex mechanical decoupling or PTTIC) requires expensive pulse tube refrigerators or extreme vibration isolation platforms, resulting in high system costs. SUMMARY

[0006] Therefore, the present application provides an optical thermostat with comprehensive vibration reduction and low-temperature in-situ displacement function, which can solve the technical problems of insufficient high-level vibration isolation capability, easy coupling of refrigerator noise to the measurement optical path, lack of low-temperature in-situ precise displacement capability, and conflict between balance thermal isolation, convenience, and cost in the prior art; and simultaneously meet the comprehensive needs of ultra-low base vibration, strong decoupling of the measurement optical path, low-temperature in-situ micron-level displacement, convenient sample replacement, and efficient refrigeration / thermal control under the support of a conventional GM refrigerator.

[0007] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows: an optical thermostat with comprehensive vibration reduction and low-temperature in-situ displacement function, comprising: a support vibration reduction frame, a suspension support system, a displacement structure, and a sample chamber.

[0008] The support vibration reduction frame is composed of a support frame, a counterweight box, and a connecting upper plate, and is used to bear the overall weight of the refrigerator and the sample chamber; the frame is arranged with an upper vibration reduction damper and a lower vibration reduction damper, which are oppositely arranged; the upper end of the frame is provided with a rigid connecting rod and a vertical bellows, the vertical bellows is used to provide flexible vibration reduction and maintain vacuum sealing, and the rigid connecting rod provides the necessary mechanical strength.

[0009] The suspension support system comprises a vacuum chamber, a horizontal bellows, a sample chamber base, a suspension support plate, and a low-frequency hinge; the vacuum chamber is suspended in the middle of the support vibration reduction frame as a whole; the vacuum chamber is flexibly connected with the sample chamber through the horizontal bellows; the sample chamber base is connected to the support vibration reduction frame through the suspension support plate and the low-frequency hinge, so that the sample chamber is rigidly supported in a static state and is low-frequency isolated in a dynamic state.

[0010] The displacement structure is a displacement stage, which is arranged outside the sample chamber and is used for micron-level displacement operation.

[0011] Further, the displacement stage is connected to the suspension support plate and the bottom of the sample chamber base.

[0012] Further, the sample chamber is composed of a sample chamber base and a sample chamber upper cover, and an optical window is arranged on the upper cover to realize optical path coupling for external optical measurement; a sample support rod is arranged in the sample chamber, and a damping member is arranged to mount the experimental sample; the sample support rod is fixed to a support plane in the chamber and is supported by a hollow heat-insulating support rod in the chamber.

[0013] Further, the optical thermostat further comprises a heat insulation and heat conduction system, including a second-level upper heat shield, a second-level lower heat shield, a second-level main heat shield, a second-level heat insulation connecting rod and a first-level heat conduction rod.

[0014] The vacuum cavity and the sample chamber are provided with a second-level upper heat shield, a second-level lower heat shield and a second-level main heat shield to form a multi-layer radiation heat shield. The second-level heat insulation connecting rod provides sufficient heat insulation space and conducts heat; the first-level heat conduction rod transmits the temperature of the cold head to the sample chamber.

[0015] The second-level heat insulation connecting rod and the second-level lower heat shield adopt flexible hinge heat conduction, the first-level cold head and the first-level heat conduction rod adopt flexible hinge heat conduction, and the first-level heat conduction rod and the sample support rod also adopt flexible hinge heat conduction.

[0016] Further, a general Gifford-McMahon closed cycle refrigerator is used as a cold source.

[0017] Further, the hinge is a cross-spring hinge, a diaphragm hinge or a hinge structure based on a low-stiffness elastomer; the low-stiffness elastomer is an O-ring pre-pressing / flexible polymer gasket.

[0018] Further, the flexible hinge is a metal woven belt or a flexible gap filled with high thermal conductivity grease / paste.

[0019] Further, the displacement table is arranged above the sample chamber base and integrated in the sample chamber to drive the sample support rod; the damping member is realized by a high-damping plastic gasket, a viscoelastic damping glue or a small air spring.

[0020] Further, the heat-insulating support rod in the chamber is G10, PEEK / CF or CFRP; or the heat-insulating support rod in the chamber is a light-weight rigid support composed of a stainless steel / titanium alloy tube.

[0021] Beneficial effects: 1. The optical thermostat provided by the present application has the functions of comprehensive vibration reduction and low-temperature in-situ displacement. The system-level vibration isolation design is a hierarchical vibration reduction + double-system frequency difference decoupling mode, which is different from the scheme of relying only on a bellows / flexible tube or a single-stage elastic connection (such as US9303914B2, CN107655236B, and CN220507416U). The present application uses an upper and lower opposing vibration absorber + a large mass base to achieve first-order to second-order inertia vibration absorption, and further achieves complete decoupling with an optical platform in a suspended non-contact manner, and the vibration transmission rate can be reduced to below 10%. The resonant frequencies of two systems (a sample stage system and a cold head system) are designed to achieve vibration decoupling.

[0022] 2. The optical thermostat provided by the present application has the functions of comprehensive vibration reduction and low-temperature in-situ displacement. The system-level vibration isolation design is a hierarchical vibration reduction + double-system frequency difference decoupling mode, which is different from the scheme of relying only on a bellows / flexible tube or a single-stage elastic connection (such as US9303914B2, CN107655236B, and CN220507416U). The present application uses an upper and lower opposing vibration absorber + a large mass base to achieve first-order to second-order inertia vibration absorption, and further achieves complete decoupling with an optical platform in a suspended non-contact manner, and the vibration transmission rate can be reduced to below 10%. The resonant frequencies of two systems (a sample stage system and a cold head system) are designed to achieve vibration decoupling.

[0023] 3. The optical thermostat provided by the present application has the functions of comprehensive vibration reduction and low-temperature in-situ displacement. The system-level vibration isolation design is a hierarchical vibration reduction + double-system frequency difference decoupling mode, which is different from the scheme of relying only on a bellows / flexible tube or a single-stage elastic connection (such as US9303914B2, CN107655236B, and CN220507416U). The present application uses an upper and lower opposing vibration absorber + a large mass base to achieve first-order to second-order inertia vibration absorption, and further achieves complete decoupling with an optical platform in a suspended non-contact manner, and the vibration transmission rate can be reduced to below 10%. The resonant frequencies of two systems (a sample stage system and a cold head system) are designed to achieve vibration decoupling. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a front view of the optical thermostat provided by the present application with the functions of comprehensive vibration reduction and low-temperature in-situ displacement; Figure 2 FIG. 2 is a side view of the optical thermostat provided by the present application with the functions of comprehensive vibration reduction and low-temperature in-situ displacement. DETAILED DESCRIPTION

[0025] The present application will be described in detail below with reference to the accompanying drawings and examples.

[0026] The present application is based on the design concept of hierarchical vibration reduction-vibration decoupling-high-efficiency heat conduction path-modular convenient design. As shown in FIGS. 1 and 2, the low-noise optical thermostat of the present application includes a support vibration reduction frame, a suspension support system, a displacement structure, a sample chamber, a decoupling design, and a heat insulation and heat conduction system. Figure 1 and Figure 2

[0027] In the embodiment of the present application, the support vibration reduction frame is composed of a support frame 1, a counterweight box 2, and a connecting upper plate 3, which is used to bear the overall weight of the refrigerator and the sample cavity, form a large mass reference, and effectively absorb residual vibrations.​Figure 1 As shown, the support frame 1 is composed of four support columns, which are vertically arranged between the upper plate 3 and the counterweight box 3, forming a frame structure; the upper damping damper 4 and the lower damping damper 5 are arranged in the frame, which are oppositely arranged and can simultaneously attenuate and absorb the vertical and horizontal vibration generated by the cold head of the refrigerator. The upper end of the frame is provided with a rigid connecting rod 6 and a vertical bellows 7, the vertical bellows is used to provide flexible damping and maintain vacuum sealing, and the rigid connecting rod 6 provides necessary mechanical strength.

[0028] In the embodiment of the present application, the suspension support system includes a vacuum cavity 8, a horizontal bellows 9, a sample chamber base 14, a suspension support plate 12 and a low-frequency hinge 13; the vacuum cavity 8 is suspended in the middle of the support damping frame as a whole. The vacuum cavity 8 is flexibly connected with the sample chamber 10 through the horizontal bellows 9, further blocking the vibration transmission. The sample chamber base 14 is connected to the support damping frame through the suspension support plate 12 and the low-frequency hinge 13, as shown in the figure. Figure 1 As shown, the suspension support plate 12 is horizontally fixed on the frame and extends out of the frame, the outermost side of the suspension support plate 12 is connected with the upper end of the frame through a hinge 13, so as to realize fixation, and the sample chamber base 14 is fixed on the suspension support plate 12, so that the sample chamber 10 is rigidly supported in a static state and is low-frequency isolated in a dynamic state. The suspension support system makes the natural frequency of the sample chamber system and the cold head system significantly different to realize effective frequency difference decoupling and isolate the vibration from the mounting platform.

[0029] In the embodiment of the present application, the displacement structure is a displacement table 11, which is arranged outside the sample chamber 10 and is used for micron-level precision displacement operation in a low-temperature environment. The low-temperature environment referred to in the present application refers to the lowest temperature to minus 269 DEG C, and the highest working temperature of the thermostat provided by the present application can reach above 200 DEG C. The displacement table 11 is arranged outside the sample chamber 10 and is used for micron-level precision displacement operation in a low-temperature environment. The displacement table 11 is connected to the suspension support plate 12 and the bottom of the sample chamber base 14, which not only ensures the rigidity and stability of the whole, but also realizes the precision adjustment of the low-temperature in-situ. In the embodiment of the present application, a low-temperature displacement table 11 is adopted, and the base of the low-temperature displacement table 11 is fixed to the suspension support plate 12. The movement output end of the displacement table 11 is connected and drives the sample chamber base 14 or a sample table direct bearing connected with the base. The hollow triangular heat insulation support structure is composed of a sample chamber 10 body or a sample chamber base 14 connected to the sample chamber 10 body through at least three in-chamber heat insulation support rods 20 at an inclined angle by an in-chamber support plane 19, which is used for maintaining the rigidity and geometric stability of the sample chamber 10 in a low-temperature environment, and providing a reference for the displacement table 11.

[0030] In the embodiment of the present application, the sample chamber 10 is composed of a sample chamber base 14 and a sample chamber upper cover 15. The upper cover is provided with an optical window 16 for coupling the optical path of external optical measurement. A sample support rod 17 is arranged in the chamber and is provided with a damping member 18 for mounting the experimental sample. The sample support rod 17 is fixed to a support plane 19 in the chamber and is supported by a hollow in-chamber heat-insulating support rod 20 to reduce the thermal conduction load. The sample chamber 10 or the optical window 16 integrated thereon relies only on the horizontal bellows 9 for support and fixation, thereby being physically disconnected from the external measurement platform and the support damping frame (no rigid short-circuit channel).

[0031] In the embodiment of the present application, the heat insulation and conduction system includes a second-level upper heat shield 21, a second-level lower heat shield 22, a second-level main heat shield 23, a second-level heat insulation connecting rod 24, and a first-level heat transfer rod 25. The second-level upper heat shield 21, the second-level lower heat shield 22, and the second-level main heat shield 23 are arranged in the vacuum cavity 8 and the sample chamber 10 to form a multi-layer radiation heat shield barrier, thereby effectively reducing the thermal load. The second-level heat insulation connecting rod 24 provides sufficient heat insulation space and conducts heat. The first-level heat transfer rod 25 efficiently transfers the low temperature of the cold head to the sample chamber 10, thereby achieving rapid cooling. Flexible hinge heat conduction is adopted between the second-level heat insulation connecting rod 24 and the second-level lower heat shield 22, between the first-level cold head 26 and the first-level heat transfer rod 25, and between the first-level heat transfer rod 25 and the sample support rod 17, thereby achieving vibration isolation while ensuring heat conduction efficiency.

[0032] At least one flexible hinge heat conduction component (or low-rigidity high-heat-conduction connector) is arranged at the key connection of the following heat conduction paths (selected or combined): between the first-level heat transfer rod 25 and the sample support rod 17, between the first-level cold head 26 and the first-level heat transfer rod 25, and between the second-level heat insulation connecting rod 24 and the second-level lower heat shield 22.

[0033] The heat shields 21, 22, and 23 are assembled together through quick-release coupling structures (such as magnetic lapping, bayonet slot / pin) and can be taken out as a module or a layered module under the condition of only opening the corresponding vacuum cavity end cover, without damaging the complete seal of the vacuum cavity.

[0034] A vibration-damping type low-temperature optical thermostat system using a conventional GM refrigerator: a low-temperature optical thermostat characterized by using a general Gifford-McMahon (GM) closed-cycle refrigerator as a cold source and integrating one or more of the structural features described in points 1-6 to achieve ultra-low working vibration and high-efficiency refrigeration cooling capacity.

[0035] In the embodiment of the present application, the low-frequency hinge 13 can be a cross-spring hinge, a diaphragm hinge, or a hinge structure based on a low-rigidity elastomer (such as an O-ring pre-pressing / flexible polymer gasket).

[0036] In the embodiments of the present application, the flexible hinge can be a metal braid (such as copper braid) or a flexible gap filled with high thermal conductivity grease / paste (but the effect can be weaker than that of an integrally formed flexible hinge).

[0037] In the embodiments of the present application, the quick-release mechanism of the heat shield can also use a sliding groove / rail with a positioning pin in addition to magnetism / bayonet.

[0038] In the embodiments of the present application, the displacement table 11 can be placed above the sample chamber base 14, integrated inside the sample chamber 10 (drive the sample support rod 17), or placed on the side to drive the push rod.

[0039] In the embodiments of the present application, the damping member 18 can be implemented by a high-damping plastic pad, a viscoelastic damping glue, or a small air spring.

[0040] In the embodiments of the present application, the in-chamber heat-insulating support rod 20 can be a high-strength low-thermal-conductivity composite material (such as G10, PEEK / CF, CFRP), or a light-weight rigid support composed of a stainless steel / titanium alloy tube.

[0041] In summary, the above is only a preferred embodiment of the present application, and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An optical thermostat with integrated vibration reduction and low-temperature in-situ displacement functions, characterized in that, The optical constant-temperature device comprises a support damping frame, a suspension support system, a displacement structure and a sample chamber (10). The support damping frame is composed of a support frame (1), a counterweight box (2) and a connecting upper plate (3) and is used for bearing the overall weight of a refrigerator and a sample cavity; an upper damping damper (4) and a lower damping damper (5) are arranged in the frame and are oppositely arranged; a rigid connecting rod (6) and a vertical bellows (7) are arranged at the upper end of the frame, the vertical bellows (7) are used for providing flexible damping and maintaining vacuum sealing, and the rigid connecting rod (6) provides necessary mechanical strength. The suspension support system comprises a vacuum cavity (8), a horizontal bellows (9), a sample chamber base (14), a suspension support plate (12) and a low-frequency hinge (13); the vacuum cavity (8) is suspended in the middle of the support damping frame as a whole; the vacuum cavity (8) is flexibly connected with the sample chamber (10) through the horizontal bellows (9); the sample chamber base (14) is connected with the support damping frame through the suspension support plate (12) and the low-frequency hinge (13), so that the sample chamber (10) is rigidly supported in a static state and is low-frequency isolated in a dynamic state. The displacement structure is a displacement table (11) and is arranged outside the sample chamber (10) and is used for micron-level displacement operation. The displacement table (11) is connected with the suspension support plate (12) and the bottom of the sample chamber base (14).

2. The optical thermostat with integrated vibration reduction and low temperature in-situ displacement according to claim 1, wherein, The sample chamber (10) is composed of the sample chamber base (14) and a sample chamber upper cover (15), the upper cover is provided with an optical window (16) and is used for realizing optical path coupling of external optical measurement; a sample support rod (17) is arranged in the sample chamber (10) and is provided with a damping damping part (18) and is used for mounting an experimental sample; the sample support rod (17) is fixed to an in-chamber support plane (19) and is supported by a hollow in-chamber heat-insulating support rod (20).

3. The optical cryostat with integrated vibration reduction and in situ displacement function according to claim 1, characterized in that, The optical constant-temperature device further comprises a heat insulation and heat conduction system, which comprises a secondary upper heat insulation cover (21), a secondary lower heat insulation cover (22), a secondary main heat insulation cover (23), a secondary heat insulation connecting rod (24) and a primary heat conduction rod (25).

4. The optical cryostat with integrated vibration and low temperature in situ displacement according to claim 1, wherein, The vacuum cavity (8) and the sample chamber (10) are provided with the secondary upper heat insulation cover (21), the secondary lower heat insulation cover (22) and the secondary main heat insulation cover (23) and form a multilayer radiation heat insulation barrier. The secondary heat insulation connecting rod (24) provides sufficient heat insulation space and conducts heat. The primary heat conduction rod (25) transmits the temperature of a cold head to the sample chamber (10). Flexible hinge heat conduction is adopted between the secondary heat insulation connecting rod (24) and the secondary lower heat insulation cover (22), between the primary cold head (26) and the primary heat conduction rod (25) and between the primary heat conduction rod (25) and the sample support rod (17). A general Gifford-McMahon closed cycle refrigerator is used as a cold source.

5. The optical cryostat with integrated vibration and in situ displacement reduction according to claim 1, characterized in that, The hinge (13) is a cross-spring hinge, a diaphragm hinge or a hinge structure based on a low-rigidity elastic body; the low-rigidity elastic body is an O-ring pre-pressing / flexible polymer gasket.

6. The optical cryostat with integrated vibration and in situ displacement reduction according to claim 1, characterized in that, The flexible hinge is a metal woven belt or a flexible gap filled with high-thermal-conductivity grease / paste.

7. The optical cryostat with integrated vibration and in situ displacement reduction according to claim 1, characterized in that, ​ 8. The optical cryostat with integrated vibration and in situ displacement reduction according to claim 1, characterized in that, The displacement table (11) is arranged above the sample chamber base (14) and integrated in the sample chamber (10) to drive the sample support rod (17); the damping member (18) is implemented by a high-damping plastic pad, a viscoelastic damping glue or a small air spring.

9. The optical cryostat with integrated vibration and in situ displacement reduction according to claim 1, characterized in that, The in-chamber heat-insulating support rod (20) is made of G10, PEEK / CF or CFRP. Or the in-chamber heat-insulating support rod (20) is a light-weight rigid support composed of a stainless steel / titanium alloy pipe.

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