Super-fine multi-position test low-temperature microscopy system and control method

Abstract

This application relates to the field of low-temperature optical microscopy imaging technology, specifically to an ultra-precise multi-position testing low-temperature microscopy system and control method. The system aims to solve the problems of significant vibration interference and difficulty in maintaining vacuum in low-temperature microscopy imaging, and includes a cooling system and a sample chamber. The cooling system mainly consists of a variable frequency compressor, a suspended bellows vibration damping mechanism, and a heat-resistant radiation shield with an adsorber. The sample chamber contains a stacked structure consisting of a sample holder, a displacement stage, and a cold plate, and is equipped with a cold shield and an adsorber. The cooling system and the sample chamber are connected by a vacuum concentric sleeve-type extended cold finger, and a flexible thermal connector is used to transfer cooling. This application significantly reduces the impact of vibration on the sample end through an absorption-type vibration damping design and variable frequency control. It also utilizes the temperature-sensitive adsorption characteristics of a multi-point adsorber layout to construct a vacuum self-balancing system, greatly improving the stability and testing efficiency of low-temperature microscopy imaging.

Description

Technical Field

[0001] This application belongs to the field of low-temperature microscopy equipment, specifically relating to an ultra-fine multi-position testing low-temperature microscopy system and control method. Background Technology

[0002] Ultra-precise measurement equipment can provide a high-precision extreme testing environment for exploring the fundamental properties of matter, quantum computing, and the characteristics of low-dimensional quantum materials. Especially for fields that rely on low-temperature spectroscopy for testing, such as quantum optics, superlattice electronic properties, and near-field optics, the requirements for the environment and testing equipment are even more stringent.

[0003] Currently, the field of ultra-precision optical measurement generally requires the integration of ultra-low temperature and ultra-low vibration systems. Existing testing systems mainly fall into two categories. One type is based on dry ultra-low vibration systems, which use cold helium gas to circulate and cool the sample chamber. This type requires a complex gas circulation system, and the entire system is expensive and complex to operate. The other type is based on wet refrigeration systems, which rely on refrigerants to cool the sample chamber. Although this type of system has no source of vibration and does not have vibration problems, it requires continuous consumption of refrigerants. The storage and use of refrigerants are unavoidable problems, especially liquid helium, whose price has soared in recent years, greatly increasing the cost of equipment use.

[0004] In view of the bottlenecks of the existing technology, the present invention provides an ultra-fine multi-position testing low-temperature microscopy system through technological innovation to overcome the above problems. Summary of the Invention

[0005] In a first aspect, this application provides an ultra-fine multi-position testing cryogenic microscopy system, including a cooling system and a sample chamber, wherein; The refrigeration system includes a refrigerator, a vibration damping mechanism, a mounting flange, an insulating shell, a heat radiation shield, an extended cooling finger, an exhaust port, and a variable frequency compressor. The vibration damping mechanism, the mounting flange, and the insulating shell are installed sequentially from top to bottom. Extended cooling fingers and horizontally extending pipes connecting to the exhaust port are connected to both ends of the bottom of the refrigerator. The refrigeration system is connected to and cools the sample chamber via the horizontally extending cooling finger. The compressor is a variable frequency compressor used to drive the refrigerator. The refrigeration system is housed within a sealed shell. The sample chamber includes a vacuum hood, a cold screen, a sample holder, a displacement stage, a cold plate, a cold plate support, and an observation window; the sample holder, displacement stage, cold plate, and cold plate support are installed from top to bottom, wherein the sample holder and displacement stage are located inside the cold screen; It also includes an adsorber; the adsorber is respectively installed in the refrigeration system and the sample chamber; The entire cooling system and the sample chamber are fixed on the mounting platform.

[0006] Preferably, as one possible implementation, the refrigeration unit includes, from top to bottom, a refrigeration unit head, a primary cooling head, and a secondary cooling head; that is, it should be noted that the external components of the refrigeration unit are driven by a variable frequency compressor; the compressor is equipped with multiple drive frequency settings, including a high-frequency drive mode and a low-frequency drive mode; The vibration damping mechanism includes a vibration damping bellows and a connecting column. The head of the refrigeration unit is located in the middle of the vibration damping assembly and is in a suspended state. The heat insulation shell and the heat radiation shield are installed sequentially from the outside to the inside; the heat insulation shell is located on the bottom surface of the mounting flange; the side of the heat insulation shell is provided with an air extraction port; the heat radiation shield is installed at the first-stage cold head; the compressor is a variable frequency drive design, and different drive frequencies can be selected according to the working state.

[0007] Preferably, as one possible implementation, the vacuum hood and the cold shield are arranged sequentially from the outside to the inside; The cold shield is a closed structure, set on the cold plate, and has a window at the same position as the vacuum hood; the sample holder, displacement stage, cold plate, and cold plate support are installed from top to bottom, wherein the sample holder and displacement stage are located inside the cold shield; the cold plate support is set below the cold plate and has a hollow structure.

[0008] Preferably, as one possible implementation, the vacuum hood has an observation window, which can be set on the side wall or the top, and a window plate or a spare blind plate is installed on it; the observation window is sealed by adhesive bonding, rubber ring or metal seal. The vacuum hood is also equipped with several electrical interfaces, which connect inward to the thermometer and heater located near the sample holder, and outward to the temperature control equipment and signal processing system. Preferably, as one possible implementation; the extended cold finger is a vacuum concentric sleeve structure, with a flexible tube on the outside and a high thermal conductivity connecting rod on the inside; one end of the high thermal conductivity connecting rod is inserted into the heat radiation shield and fixed to the bottom of the secondary cold head, and the other end is fixed to the cold plate through a flexible thermal connection; one end of the flexible tube is connected to the heat insulation shell of the refrigeration system, and the other end of the flexible tube is connected to the vacuum cover of the sample chamber, which is generally a flexible corrugated tube; Preferably, as one possible implementation, the sample holder and the cold plate, and the extended cold finger and the cold plate are all connected by a highly thermally conductive flexible thermal connection.

[0009] Preferably, as one possible implementation, the refrigeration system shares a vacuum with the sample chamber; specifically, the internal space formed by the heat-insulating shell, the bellows, and the vacuum hood is interconnected.

[0010] Preferably, as one possible implementation, the adsorber is disposed on a heat radiation shield, two-stage cold head, cold shield and cold plate, and is filled with a temperature-sensitive active adsorbent. The outer shell of the adsorber is generally an open cylindrical structure.

[0011] In addition, this invention provides a control method for an ultra-fine multi-position testing low-temperature microscopy system, including the following operation steps: Step S1 Initial cooling preparation: First, connect the compressor to the refrigeration unit, connect the air extraction port to the external vacuum pump group, and connect the electrical interface to the external temperature control device. Step S2: Vacuum environment is obtained and the operation is performed. The evacuation port is opened and the external pump group performs evacuation treatment on the interconnected cooling system space and sample chamber space. After the vacuum degree reaches the preset vacuum degree threshold, the pumping operation continues. Step S3: The low-temperature environment is obtained and the operation is performed by starting the power supply of the refrigeration unit and compressor, setting the compressor to the high-frequency drive position, setting the target temperature through the temperature control device, and lowering the system temperature to the preset minimum temperature state. Step S4 is the variable temperature test operation. After the temperature drops to the preset minimum temperature, the suction port and external pump group are closed, the compressor drive frequency is switched to the low frequency level, and the sample temperature is adjusted by the temperature control device. During this process, the vacuum degree in the system is automatically balanced by the adsorption and degassing characteristics of the multi-position built-in adsorber, and the displacement stage is driven to move the sample position in a programmed manner to complete the signal acquisition under multi-position and variable temperature conditions.

[0012] Compared with the prior art, this application has the following advantages: This invention achieves a highly stable testing environment through a three-stage progressive vibration reduction architecture. The first stage is a suspended bellows vibration reduction design at the refrigerator head, which weakens most of the mechanical impact at the source by placing the core components of the refrigerator in an elastically suspended state. The second stage is a concentric flexible structure extending the cold finger, which uses non-rigid connections to cut off the solid-state transmission path of vibration waves. The third stage is the low-frequency operation mode of the variable frequency compressor, which further reduces the intensity of the vibration source during the critical stage of signal acquisition. With the synergistic effect of multiple stages, the residual vibration level transmitted to the sample end is reduced to below a preset threshold, which can meet the stringent requirements of near-field optics and atomic-resolution microscopic imaging.

[0013] This invention successfully eliminates dependence on scarce refrigerants such as liquid helium, and also eliminates the need for complex external helium circulation pipelines. The system can achieve long-term ultra-low temperature operation with only standard electric drive. In particular, through the scientific layout of multi-position built-in adsorbers, the system achieves self-regulation and self-maintenance of the internal vacuum, eliminating dependence on external molecular pumps that are subject to vibration interference. This integrated and compact design significantly reduces the manufacturing cost and daily maintenance complexity of the equipment. At the same time, through the optimized combination of high-purity oxygen-free copper heat radiation shield and low thermal conductivity support structure, this invention minimizes parasitic heat load. Even with a large-size cold plate and precision displacement stage, it can still maintain extremely fast cooling efficiency and high-precision temperature control. The realization of multi-station automatic switching function allows researchers to continuously probe multiple samples without compromising the vacuum and cryogenic environment, greatly improving experimental efficiency.

[0014] These or other aspects of this application will become more apparent in the following description of the embodiments. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This invention provides a schematic diagram of the oblique view structure of an ultra-fine multi-position testing cryogenic microscopy system.

[0017] Figure 2 This paper shows a side front view of a cryogenic microscopy system for ultra-fine multi-position testing provided in this application.

[0018] Figure 3 This paper shows a schematic diagram of the internal structure of an ultra-fine multi-position testing cryogenic microscopy system provided in this application;

[0019] Figure 4 A perspective view of the sample chamber in an ultra-fine multi-position low-temperature microscopy system provided in this application;

[0020] Figure 5 A cross-sectional view of the sample chamber in an ultra-fine multi-position low-temperature microscopy system provided in this application;

[0021] Figure 6 A flowchart of a control method for an ultra-fine multi-position cryogenic microscopy system provided in this application;

[0022] The components include: 1. Refrigeration system; 2. Sample chamber; 3. Refrigeration unit; 4. Vibration damping mechanism; 5. Mounting flange; 6. Insulating shell; 7. Heat radiation shield; 8. Extended cold finger; 9. Evacuation port; 10. Vacuum hood; 11. Cold shield; 12. Sample holder; 13. Cold plate; 14. Cold plate support; 15. Observation window; 16. Adsorber; 17. Enclosed shell; 18. Primary cold head; 19. Secondary cold head; 20. Vibration damping bellows; 21. Connecting column; 22. Thermal connection; 23. Hose; 24. Connecting rod; 25. Compressor; 26. Displacement stage. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0024] In some of the processes described in the specification, claims, and accompanying drawings of this application, multiple operations appear in a specific order. However, it should be clearly understood that these operations may not be executed in the order they appear herein, or may be executed in parallel. The sequence numbers are merely used to distinguish different operations, and the sequence numbers themselves do not represent any execution order. Furthermore, these processes may include more or fewer operations, and these operations may be executed sequentially or in parallel. It should be noted that the descriptions such as "first," "second," etc., used herein are used to distinguish different messages, devices, modules, etc., and do not represent a sequential order, nor do they limit "first" and "second" to different types.

[0025] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Example 1 See Figure 1 , Figure 2 as well as Figure 3 , Figure 1 This application provides an ultra-fine multi-position testing cryogenic microscopy system, including a cooling system 1 and a sample chamber 2, wherein; The refrigeration system 1 includes a refrigerator 3, a vibration damping mechanism 4, a mounting flange 5, a heat insulation shell 6, a heat radiation shield 7, an extended cooling finger 8, an exhaust port 9, and a variable frequency compressor 25; wherein, the vibration damping mechanism 4, the mounting flange 5, and the heat insulation shell 6 are installed sequentially from top to bottom; an extended cooling finger and a horizontally extending pipe connecting to the exhaust port are respectively connected to both ends of the bottom of the refrigerator 3; the refrigeration system 1 is connected to the sample chamber 2 through the horizontally extending cooling finger 8 and cools it (i.e., the refrigeration system 1 and the sample chamber 2 are connected through the horizontally extending cooling finger 8); the compressor 25 is used to drive the refrigerator 3; the refrigeration system is built into a closed shell 17. See also Figure 4 and Figure 5 The sample chamber 2 includes a vacuum hood 10, a cold screen 11, a sample holder 12, a displacement stage 26, a cold plate 13, a cold plate support 14, and an observation window 15; the sample holder 12, the displacement stage, the cold plate 13, and the cold plate support 14 are installed from top to bottom, wherein the sample holder 12 and the displacement stage are located inside the cold screen 11. The adsorber 16 is respectively disposed in the refrigeration system 1 and the sample chamber 2; The entire cooling system 1 and the sample chamber 2 are fixed on the mounting platform.

[0027] Preferably, as one possible implementation, the refrigerator 3 includes, from top to bottom, a refrigerator head, a primary cold head 18, and a secondary cold head 19. The refrigerator, with its refrigerator head, primary cold head, and secondary cold head arranged from top to bottom, is powered by a compressor with a variable frequency drive design. Specifically, the refrigerator 3 is externally driven by a compressor 25. The compressor has multiple drive frequency settings, including a high-frequency drive mode and a low-frequency drive mode. In the high-frequency drive mode, the system has a higher cooling capacity and a faster cooling rate, used for the initial cooling stage. In the low-frequency drive mode, the mechanical vibration amplitude generated by the reciprocating motion inside the compressor is significantly reduced, used for the high-precision signal acquisition stage. The working principle of the refrigerator is based on the compression and expansion cycle of helium in different temperature zones. The primary cold head provides a preset first temperature zone pre-cooling environment, and the secondary cold head provides a preset second temperature zone ultra-low temperature environment. The vibration damping mechanism 4 includes a damping bellows and connecting columns. The refrigerator head is located in the middle of the vibration damping assembly and is in a suspended state. The core components of the vibration damping mechanism include the damping bellows and connecting columns. The damping bellows adopt a multi-stage vibration damping structure design, specifically with at least one upper bellows and one lower bellows, respectively installed at both ends of the refrigerator head. The connecting columns are made of stainless steel and are used to provide rigid support and physical isolation for the bellows at each stage and the refrigerator head, ensuring that the refrigerator head is in a completely suspended motion state within the vibration damping mechanism. This suspension structure can convert the mechanical vibration kinetic energy generated by the refrigerator operation into the elastic potential energy of the bellows and dissipate it, preventing the direct transmission of vibration to the mounting flange and subsequent experimental components.

[0028] The heat insulation shell 6 and the heat radiation shield 7 are installed sequentially from the outside to the inside; the heat insulation shell 6 is located on the bottom surface of the mounting flange 5; the heat insulation shell 6 has an air extraction port 9 on its side; the heat radiation shield 7 is installed at the first-stage cold head 18; the compressor 25 is a variable frequency drive design, and different drive frequencies can be selected according to the working state.

[0029] In the above specific technical solution, the heat insulation shell 6 and the heat radiation shield 7 are installed concentrically from the outside to the inside. The heat insulation shell 6 is fixed to the bottom surface of the mounting flange and is made of highly polished stainless steel, utilizing its extremely low surface emissivity to reduce the room temperature heat radiation load of the external environment on the internal low-temperature region. The heat radiation shield 7 is installed at the primary cold head and is made of high-purity oxygen-free copper, which has good thermal conductivity and provides an isothermal zone for the secondary cold head.

[0030] The vacuum chamber 10 and the cold shield are arranged sequentially from the outside to the inside. The cold shield is a closed structure, mounted on the cold plate, and has a window at the same position as the vacuum chamber. The sample holder 12, the displacement stage, the cold plate 13, and the cold plate support 14 are installed from top to bottom, with the sample holder and the displacement stage located inside the cold shield. The cold plate support is located below the cold plate and has a hollow structure. The cold plate support base is located below the cold plate and has a hollow structure, generally made of materials with poor thermal conductivity and good support conditions, such as PEEK or G10. In the above specific technical solution, the displacement stage may include basic motion components and advanced motion components, and may be capable of single-axis, two-dimensional, or three-dimensional motion, driving the sample to move synchronously. The cold plate support is located below the cold plate and has a hollow structure, generally made of materials with poor thermal conductivity but good support conditions, such as PEEK, G10, etc. The vacuum chamber has an observation window, which can be installed on the side wall or the top, and a window plate or a spare blind plate is installed on it; the observation window is sealed by adhesive bonding, rubber ring or metal sealing ring. The vacuum chamber is also equipped with several electrical interfaces, which connect inward to a thermometer and heater located near the sample holder, and outward to a temperature control device and a signal processing system. In the above specific technical solution, the vacuum chamber is equipped with an observation window and several electrical interfaces. The observation window is fitted with a window plate or a spare blind plate, and is generally sealed with adhesive, rubber rings, or metal seals. Its position can be on the side wall or top of the vacuum chamber. The electrical interfaces are located on the side wall of the vacuum chamber, with one end connecting to the thermometer, heater, and sample holder located near the sample holder, and the other end connecting to an external temperature control device and a signal processing system to realize the regulation of the sample environment and signal acquisition.

[0031] The extended cold finger 8 is a vacuum concentric sleeve structure, with a flexible hose on the outside and a high thermal conductivity connecting rod on the inside. One end of the connecting rod is inserted into the heat radiation shield and fixed to the bottom of the secondary cold head, while the other end is fixed to the cold plate via a flexible thermal connection. One end of the flexible hose is connected to the heat insulation shell of the refrigeration system, and the other end is connected to the vacuum hood of the sample chamber. It is generally a flexible corrugated pipe. The internal space formed by the heat insulation shell, the flexible hose, and the vacuum hood is interconnected. In the above specific technical solution, the extended cold finger 8 is a vacuum concentric structure, with a flexible tube on the outside and a high thermal conductivity connecting rod on the inside; one end of the high thermal conductivity connecting rod is inserted into the heat radiation shield and fixed to the bottom of the secondary cold head, and the other end is fixed to the cold plate through a flexible thermal connection; one end of the flexible tube is connected to the heat insulation shell of the refrigeration system, and the other end of the flexible tube is connected to the vacuum cover of the sample chamber, which is generally a flexible corrugated tube; The sample holder 12 and the cold plate 13, as well as the extended cold finger 8 and the cold plate 13, are connected by a highly thermally conductive flexible thermal connection. The refrigeration system 1 and the sample chamber 2 share a vacuum; specifically, the internal space formed by the insulating shell, the bellows, and the vacuum hood are interconnected.

[0032] The adsorber is mounted on a heat radiation shield, two-stage cold heads, a cold shield, and a cold plate. It is filled with a temperature-sensitive active adsorbent, and the adsorber shell is generally an open cylindrical structure.

[0033] In the above specific technical solution, the adsorber is respectively set inside the refrigerator and the sample chamber, specifically set in the heat radiation shield, two-stage cold head, cold shield and cold plate. It is filled with temperature-sensitive active adsorbent, which can adsorb gas in a low temperature environment and release the absorbed gas at a slightly higher temperature. The outer shell of the adsorber is generally an open cylindrical structure.

[0034] Example 2 See Figure 6 Embodiment 2 of the present invention provides a control method for an ultra-fine multi-position testing cryogenic microscopy system, comprising the following operation steps: Step S1 Initial cooling preparation: First connect the compressor and the refrigeration unit, connect the air extraction port to the external vacuum pump group, and connect the electrical interface to the external temperature control device. Step S2: Vacuum environment is obtained and the operation is performed. The evacuation port is opened and the external pump group performs evacuation treatment on the interconnected cooling system space and sample chamber space. After the vacuum degree reaches the preset vacuum degree threshold, the pumping operation continues. Step S3: The low-temperature environment is obtained and the operation is performed by starting the power supply of the refrigeration unit and compressor, setting the compressor to the high-frequency drive position, setting the target temperature through the temperature control device, and lowering the system temperature to the preset minimum temperature state. Step S4 is the variable temperature test operation. After the temperature drops to the preset minimum temperature, the suction port and external pump group are closed, the compressor drive frequency is switched to the low frequency level, and the sample temperature is adjusted by the temperature control device. During this process, the vacuum degree in the system is automatically balanced by the adsorption and degassing characteristics of the multi-position built-in adsorber, and the displacement stage is driven to move the sample position in a programmed manner to complete the signal acquisition under multi-position and variable temperature conditions.

[0035] The aforementioned ultra-fine multi-position testing cryogenic microscopy system and control method can be achieved through the following steps: During the initial cooling preparation process, first, correctly connect all components of the system, specifically connecting the compressor to the refrigeration unit, the air extraction port to the external vacuum pump group, and the external temperature control device to the electrical interface. Subsequently, the vacuum environment and the low-temperature environment were obtained. The vacuum environment was obtained by opening the evacuation port and using an external pump to evacuate the common vacuum cooling system and sample chamber until the vacuum level reached 1×10⁻⁶. -4 After reaching mbar, begin cooling preparation and continue pumping; once the low-temperature environment is achieved, turn on the power to the chiller and compressor, set the compressor to high frequency, set the target temperature through the temperature control device, and perform cooling operation on the system until the temperature drops to a minimum of <2.6K. During the variable temperature test, firstly, after the system temperature drops to the lowest level, the exhaust port and external pump power are turned off, and the compressor operating frequency is adjusted to a low frequency setting. Secondly, the sample position is moved to the set position by the displacement stage. Then, the sample signal is collected at different temperatures from low to high using the temperature control device. During this process, the adsorber in the sample chamber will release gas, while the adsorption pump in the refrigeration system remains at a low temperature and will continue to adsorb the gas released by the adsorber in the sample chamber, thereby maintaining the vacuum in the sample chamber and preventing ice crystals from forming on the sample surface. The sample position is then moved again by the displacement stage to complete the acquisition of sample information under different positions and temperatures.

[0036] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A low-temperature microscopy system for ultra-fine multi-position testing, characterized in that, include: The cooling system and the sample chamber, wherein; The refrigeration system includes a refrigerator, a vibration damping mechanism, a mounting flange, an insulating shell, a heat radiation shield, an extended cooling finger, an exhaust port, and a variable frequency compressor. The vibration damping mechanism, the mounting flange, and the insulating shell are installed sequentially from top to bottom. An extended cooling finger and a horizontally extending pipe connecting to the exhaust port are connected to both ends of the bottom of the refrigerator. The refrigeration system is connected to and cools the sample chamber via the horizontally extending cooling finger. The compressor is a variable frequency compressor used to drive the refrigerator. The refrigeration system is housed within a sealed shell. The sample chamber includes a vacuum hood, a cold screen, a sample holder, a displacement stage, a cold plate, a cold plate support, and an observation window; the sample holder, displacement stage, cold plate, and cold plate support are installed from top to bottom, wherein the sample holder and displacement stage are located inside the cold screen; It also includes an adsorber; the adsorber is respectively installed in the refrigeration system and the sample chamber; The entire cooling system and the sample chamber are fixed on the mounting platform.

2. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The refrigeration unit, from top to bottom, includes a refrigeration head, a primary cooling head, and a secondary cooling head; the compressor is equipped with multiple drive frequency settings, including a high-frequency drive mode and a low-frequency drive mode; The vibration damping mechanism includes a vibration damping bellows and a connecting column. The head of the refrigeration unit is located in the middle of the vibration damping assembly and is in a suspended state. The heat insulation shell and the heat radiation shield are installed sequentially from the outside to the inside; the heat insulation shell is located on the bottom surface of the mounting flange; the side of the heat insulation shell is provided with an air extraction port; the heat radiation shield is installed at the first-stage cold head.

3. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The vacuum hood and the cold shield are arranged sequentially from the outside to the inside; The cold shield is a closed structure, set on the cold plate, and has a window at the same position as the vacuum hood; the sample holder, displacement stage, cold plate, and cold plate support are installed from top to bottom, wherein the sample holder and displacement stage are located inside the cold shield; the cold plate support is set below the cold plate and has a hollow structure.

4. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The vacuum chamber has an observation window, which can be installed on the side wall or the top, and a window plate or a spare blind plate is installed on it; the observation window is sealed by adhesive bonding, rubber ring or metal seal. The vacuum hood is also equipped with several electrical interfaces, which connect inward to thermometers and heaters located near the sample holder, and outward to temperature control equipment and signal processing system.

5. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The extended cold finger is a vacuum concentric sleeve structure, with a flexible tube on the outside and a high thermal conductivity connecting rod on the inside. One end of the high thermal conductivity connecting rod is inserted into the heat radiation shield and fixed to the bottom of the secondary cold head, and the other end is fixed to the cold plate through a flexible thermal connection. One end of the flexible tube is connected to the heat insulation shell of the refrigeration system, and the other end of the flexible tube is connected to the vacuum cover of the sample chamber.

6. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The sample holder and the cold plate, as well as the extended cold finger and the cold plate, are all connected by a highly thermally conductive flexible thermal connection.

7. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The refrigeration system shares a vacuum with the sample chamber, and the internal space formed by the heat insulation shell, the bellows, and the vacuum hood is interconnected.

8. The ultra-fine multi-position low-temperature microscopy system according to claim 1, characterized in that, The adsorber is mounted on a heat radiation shield, two-stage cold heads, a cold shield, and a cold plate. It is filled with a temperature-sensitive active adsorbent, and the adsorber shell is generally an open cylindrical structure.

9. A control method for an ultra-fine multi-position testing cryogenic microscopy system, characterized in that, The following steps are included: Step S1 Initial cooling preparation: First, connect the compressor to the refrigeration unit, connect the air extraction port to the external vacuum pump group, and connect the electrical interface to the external temperature control device. Step S2: Vacuum environment is obtained and the operation is performed. The evacuation port is opened and the external pump group performs evacuation treatment on the interconnected cooling system space and sample chamber space. After the vacuum degree reaches the preset vacuum degree threshold, the pumping operation continues. Step S3: The low-temperature environment is obtained and the operation is performed by starting the power supply of the refrigeration unit and compressor, setting the compressor to the high-frequency drive position, setting the target temperature through the temperature control device, and lowering the system temperature to the preset minimum temperature state. Step S4 is the variable temperature test operation. After the temperature drops to the preset minimum temperature, the suction port and external pump group are closed, the compressor drive frequency is switched to the low frequency level, and the sample temperature is adjusted by the temperature control device. During this process, the vacuum degree in the system is automatically balanced by the adsorption and degassing characteristics of the multi-position built-in adsorber, and the displacement stage is driven to move the sample position in a programmed manner to complete the signal acquisition under multi-position and variable temperature conditions.

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