Microscopic cryostat

Abstract

A microscopic cryostat comprises a supporting base, a vacuum shell, a vacuum shell top cover, a cold shield, a cold shield top cover, a cold shield support, a sample holder support, a sample holder, an extension cold finger, a sample seat, a window and pipe legs. The thermostat sequentially comprises a vacuum shell, a cold screen support, a cold screen, a sample holder support and a sample holder from outside to inside, the vacuum shell is mounted on a supporting base, and pipe legs are mounted on the side wall of the vacuum shell. According to the utility model, a heat insulation supporting structure and a damping design are adopted, the vibration level is at the nanoscale, the coaxial inlet and outlet pipeline design can work in any direction and is matched with most commercial microscopes and spectrometers for use, and the device has the characteristics of high cooling speed, large temperature change range and good temperature stability.

Description

Technical Field

[0001] The utility model belongs to the technical field of low-temperature microscopic optical physics experimental devices, and in particular relates to a microscopic low-temperature thermostat. Background Art

[0002] Traditional cryogenic optical devices are relatively heavy, usually with a refrigerant storage tank structure, which requires refrigerant replenishment and has very strict requirements on the working direction. They can only test basic optical properties at ordinary low temperatures. Some cryogenic optical devices without a storage tank structure need to rely on refrigerators to provide cold sources, but due to the influence of the working principle of the refrigerator, the vibration of the cryogenic device is very large, and it is also unable to meet the requirements of some high-precision test experiments. For example, when testing single quantum dots, single molecules and low-dimensional materials, the requirements for the cryogenic platform are very high, usually requiring extremely low temperatures, low vibration, low drift, and the ability to work in any direction. Ordinary refrigerator thermostats are difficult to meet such requirements.

[0003] Based on the above situation, a new type of microscopic cryostat is urgently needed to solve the problem. Utility Model Content

[0004] In order to solve the deficiencies in the prior art, the purpose of the utility model is to provide a microscope low-temperature thermostat. The vibration level of the low-temperature thermostat is reduced to the nanometer level through the insulation support structure and shock-absorbing design. The extended cold finger design shortens the working distance. The coaxial inlet and outlet pipeline design of the tube legs makes the thermostat compatible with most commercial microscopes and spectrometers, broadening the sample testing range. The thermostat as a whole has the characteristics of low temperature, low vibration, low drift, wide temperature range and good temperature stability.

[0005] The technical solution adopted by the utility model is as follows:

[0006] A microscopic cryostat comprises: a support base, a vacuum shell, a vacuum shell top cover, a cold screen, a cold screen top cover, a cold screen support, a sample holder, a sample holder support, an extended cold finger, a sample holder, and a tube leg.

[0007] The vacuum shell is installed on the supporting base; the thermostat is composed of the vacuum shell, the cold screen and the sample holder from the outside to the inside; the sample holder, the extended cold finger and the sample holder are installed in sequence from bottom to top; the cold screen is fixed to the inner wall of the vacuum shell through the cold screen support; the sample holder is fixed to the inner wall of the cold screen through the sample holder support; the tube legs are installed on the side wall of the vacuum shell, and the shell is provided with a liquid inlet, an air outlet, a heater, a vacuum port and a safety valve, and the internal plug is connected to the sample holder.

[0008] Preferably, the bottom end of the vacuum housing is mounted on the support base, and the top end is mounted on the vacuum housing cover; the vacuum housing and the vacuum housing cover are made of stainless steel; the vacuum housing cover is a cylindrical structure with a window and a window sheet.

[0009] Preferably, the cold screen is fixed on the vacuum housing through a cold screen support; a cold screen top cover is fixed on the top of the cold screen; the cold screen is made of gold-plated copper, and the cold screen top cover is made of stainless steel, and both are cylindrical in shape.

[0010] Preferably, the cold shield support and the sample holder support are fan-shaped thin plates, both of which are made of glass fiber composite materials.

[0011] Preferably, the tube legs are of a concentric structure, with an outer shell and an insert from the outside to the inside; the outer shell of the tube legs is connected to the vacuum shell; the outer shell and the insert are both made of stainless steel; the interior of the outer shell and the interior of the vacuum shell are a common vacuum environment; the insert is of a hollow structure, connected by a welded bellows in the middle; the insert is gold-plated oxygen-free copper about 3-5 cm from one side of the sample holder, and is tightly connected to the sample holder.

[0012] Preferably, the liquid inlet is connected to an external cold source, and the cold energy of the refrigerant reaches the sample holder through the insert of the tube leg; the heater is a ring structure, wrapping the outer shell and the air outlet of the tube leg; the air outlet is connected to the inside of the insert to discharge the vaporized refrigerant gas; the vacuum port is connected to an external pump group.

[0013] Preferably, the electrical connector is internally connected to the thermometer and heater leads of the thermostat, and externally connected to a temperature controller.

[0014] Preferably, the extended cold finger is located at the center of the entire thermostat and is made of gold-plated oxygen-free copper; the sample holder is fixed on the extended cold finger and is made of gold-plated oxygen-free copper.

[0015] Preferably, the centers of the vacuum housing top cover window, the sample holder, the extended cold finger, and the sample holder are on the same straight line.

[0016] Preferably, the support base is fixed to the optical platform to support the entire cryostat.

[0017] The utility model has the following technical effects:

[0018] 1) The utility model adopts an insulating support structure to fix the cold screen and the sample holder, which reduces the heat load of the entire low-temperature device and reduces the temperature quickly;

[0019] 2) The tube legs adopt a coaxial inlet and outlet pipeline design, which can work in any direction, saving experimental space and can be matched with most commercial microscopes and spectrometers;

[0020] 3) The inside of the tube leg is equipped with a welded bellows shock-absorbing design to reduce the vibration caused by the sudden increase in volume due to temperature changes when the refrigerant vaporizes. The vibration level is controlled at <5nm and the drift level is <2nm / min.

[0021] 4) The extended cold finger design shortens the sample working distance during testing and increases the sample testing range. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an oblique view of the device of the utility model;

[0023] Figure 2 It is a front view of the device of the utility model;

[0024] Figure 3 It is a system schematic diagram of a closed-cycle micro-cryogenic device;

[0025] Among them: 1. Support base; 2. Tube legs; 3. Vacuum shell; 4. Vacuum shell top cover; 5. Cold screen; 6. Cold screen top cover; 7. Cold screen support; 8. Sample holder; 9. Sample holder support; 10. Extended cold finger; 11. Sample holder; 12. Electrical interface; 13. Helium circulation cooling system; 14. Super-insulating flexible pipeline; 15. Flexible bellows; 201. Liquid inlet; 202. Gas outlet; 203. Heater; 204. Vacuum port; 205. Safety valve; 206. Shell; 207. Insert; 208. Welding bellows. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. The embodiments described in this application are only part of the embodiments of the utility model, not all of them. Based on the spirit of the utility model, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the utility model.

[0027] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0028] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0029] like Figure 1 , 2 As shown, a microscopic cryostat of the utility model comprises: a support base 1, a vacuum housing 3, a vacuum housing top cover 4, a cold shield 5, a cold shield top cover 6, a cold shield support 7, a sample holder 8, a sample holder support 9, an extended cold finger 10, a sample holder 11, and a tube leg 2;

[0030] The thermostat is composed of a vacuum housing 3, a cold shield 5, and a sample holder 8 from the outside to the inside; the sample holder 8, an extended cold finger 10, and a sample holder 11 are installed in sequence from bottom to top; the cold shield 5 is fixed to the inner wall of the vacuum housing 3 through a cold shield support 7; the sample holder 8 is fixed to the inner wall of the cold shield through a sample holder support 9; the tube leg 2 is installed on the side wall of the vacuum housing 3, and a liquid inlet 201, an air outlet 202, a heater 203, a vacuum port 204, a safety valve 205, and an internal plug 207 connected to the sample holder 8 is provided on the housing 206;

[0031] The bottom end of the vacuum shell 3 is installed on the supporting base 1, and the top end is installed with a vacuum shell cover 4; the vacuum shell and the vacuum shell cover are made of stainless steel; the vacuum shell cover is a cylindrical structure, with a window on the top and a quartz window piece installed.

[0032] In a preferred but non-limiting embodiment of the present invention, the window piece is any one of a quartz window, a beryllium window, and a sapphire window; the window can be a flat window or a dome structure, and the dome structure is often used in high-energy physics or X-ray diffraction; the window position can also be on the side of the vacuum shell, and the specific position and number can be determined according to experimental requirements.

[0033] The cold screen 5 is fixed on the vacuum housing 3 through the cold screen support 6, and the cold screen is made of gold-plated copper; a cold screen top cover 6 is fixed on the top of the cold screen, and the cold screen top cover is made of stainless steel, and both are cylindrical in shape;

[0034] The extended cold finger 10 is mounted on the sample holder 8, located in the center of the entire thermostat, and is made of gold-plated oxygen-free copper;

[0035] The sample holder 11 is fixed on the extended cold finger 10 and is made of gold-plated oxygen-free copper; a double-air film diamond press and a nanopositioning stage can be integrated at the sample holder;

[0036] The centers of the top cover window of the vacuum housing, the sample holder, the extended cold finger and the sample holder are on the same straight line.

[0037] In a preferred but non-limiting embodiment of the present invention, the length of the extended cold finger can be changed according to the test requirements to adjust the working distance;

[0038] The vacuum housing top cover together with the wrapped cold shield top cover and the extended cold finger structure can be replaced with a flat plate structure, and the working distance will be increased.

[0039] The cold screen support 7 and the sample holder support 9 are fan-shaped thin plates, both of which are glass fiber composite materials, specifically G10 material, which has poor thermal conductivity and is conducive to maintaining the lowest temperature of the sample holder.

[0040] The tube leg 2 is a concentric structure, which includes a shell 206 and a core 207 from the outside to the inside, and the shell is made of stainless steel;

[0041] The outer shell of the tube leg 2 is connected to the vacuum shell 3, and the interior of the outer shell and the interior of the vacuum shell form a common vacuum environment.

[0042] The insert 207 is a hollow structure, with refrigerant flowing in the inner core. The two ends of the insert are stainless steel tubes, and the middle is connected by a welded bellows 208, and the outer diameter of the bellows is 27mm. The welded bellows can reduce the gas vibration caused by the sudden increase in volume of the refrigerant in the insert due to vaporization, so that the entire low-temperature thermostat maintains low vibration characteristics.

[0043] The insert 207 is made of gold-plated oxygen-free copper about 3-5 cm near the sample holder 8 and is tightly connected to the sample holder 8 .

[0044] The liquid inlet 201 is connected to an external cold source, and the cold energy of the refrigerant reaches the sample holder through the insert of the tube leg;

[0045] In a preferred but non-limiting embodiment of the present invention, the external cold source may be liquid nitrogen or liquid helium, which is connected to the thermostat via a liquid helium transmission pipeline. Such a system requires continuous consumption of refrigerant;

[0046] In a further preferred but non-limiting embodiment, the liquid inlet is connected to the helium circulation cooling system through an ultra-insulating flexible pipeline 14, and the cold energy reaches the sample holder 8 through the insert 207 of the tube leg; the gas outlet 202 is connected to the gas processing module of the system to recover the helium, and the microscope thermostat and the helium cooling system as a whole constitute a closed-loop system.

[0047] It is worth noting that the vaporized refrigerant still has residual coldness, and frost or water droplets will form when it encounters water vapor at the outlet. Installing a heater 203 can prevent this phenomenon from happening. The heater 203 is a ring-shaped structure that wraps the outer shell and the air outlet of the tube leg.

[0048] The vacuum port 204 is connected to an external pump group to evacuate the entire thermostat;

[0049] The safety valve 205 can withstand an ultimate pressure of 0.4PSI to prevent the gas pressure inside the thermostat from being too high and causing an explosion;

[0050] The electrical connector is connected to the thermometer and heater leads inside the thermostat, and to the temperature controller outside. Combined with the dual temperature control mode, the low temperature thermostat can be precisely controlled, with a temperature stability better than ±25mK.

[0051] The support base 1 is fixed on the optical platform to support the entire cryostat.

[0052] It is worth noting that in the low-temperature thermostat described in this application, the temperature variation range is <1.8K-420K, which is an ideal low-temperature platform for testing single quantum dots, single molecules and low-dimensional materials, and has a wide range of applications in high-energy physics, neutron scattering, microscopic testing and other fields.

[0053] In one embodiment of the present invention, the external cold source is a helium circulation cooling system, such as Figure 3 As shown, a closed-loop micro-low temperature device consisting of a micro-low temperature thermostat and a helium circulation cooling system 13, wherein the super-insulated flexible pipeline 14 of the helium circulation cooling system is inserted into the liquid inlet on the tube leg, and the flexible pipeline is connected to the gas outlet. When the system is working, firstly, the sample to be tested is installed, and the top cover of the cold screen and the top cover of the vacuum shell are sealed; secondly, the test system is built, and the low temperature thermostat is connected to the helium circulation cooling system, the vacuum pump group, and the temperature controller respectively, and the temperature controller is started to display the temperature of the low temperature thermostat in real time; then the helium circulation cooling system is started, and the vacuum pump group is started after the cold source reaches the lowest temperature; finally, the low temperature thermostat is evacuated through the vacuum port, and when the vacuum degree reaches 10 -4 mbar, the super-insulated flexible pipeline of the helium circulation cooling system is inserted into the liquid inlet of the cryostat to cool the cryostat. After the cryostat reaches the lowest temperature, the temperature controller is used to control the temperature of the cryostat according to the experimental needs to complete the sample testing and data acquisition.

[0054] The beneficial effect of the utility model is that, compared with the prior art,

[0055] 1) The utility model adopts an insulating support structure to fix the cold screen and the sample holder, which reduces the heat load of the entire low-temperature device and reduces the temperature quickly;

[0056] 2) The tube legs adopt a coaxial inlet and outlet pipeline design, which can work in any direction, saving experimental space and can be matched with most commercial microscopes and spectrometers;

[0057] 3) The inside of the tube leg is equipped with a welded bellows shock-absorbing design to reduce the vibration caused by the sudden increase in volume due to temperature changes when the refrigerant vaporizes. The vibration level is controlled at <5nm and the drift level is <2nm / min.

[0058] 4) The extended cold finger design shortens the sample working distance during testing and increases the sample testing range.

[0059] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A microscope cryostat, comprising a support base, a vacuum housing, a vacuum housing top cover, a cold shield, a cold shield top cover, a cold shield support, a sample holder, a sample holder support, an extended cold finger, a sample holder and a tube leg, characterized in that: The vacuum housing is mounted on a support base; The thermostat consists of a vacuum shell, a cold shield, and a sample holder from the outside to the inside. The sample holder, extended cold finger, and sample holder are installed from bottom to top; The cold screen is fixed to the inner wall of the vacuum housing through a cold screen support; The sample holder is fixed to the inner wall of the cold screen through a sample holder support; The tube legs are installed on the side wall of the vacuum shell, and the shell is provided with a liquid inlet, a gas outlet, a heater, a vacuum port, a safety valve, and an internal insert connected to the sample holder.

2. A microscopic cryostat according to claim 1, characterized in that: The bottom end of the vacuum housing is installed on the supporting base, and the top end is installed on the vacuum housing top cover; The vacuum housing and the vacuum housing top cover are made of stainless steel; The top cover of the vacuum shell is a cylindrical structure with a window opened thereon and a window sheet installed thereon.

3. A microscopic cryostat according to claim 1, characterized in that: The cold screen is fixed to the vacuum housing via a cold screen support; A cold screen top cover is fixed on the top of the cold screen; The cold screen is made of gold-plated copper, and the cold screen top cover is made of stainless steel, both of which are cylindrical in shape.

4. A microscopic cryostat according to claim 3, characterized in that: The cold screen support and sample holder support are fan-shaped thin plates, both of which are made of glass fiber composite materials.

5. A microscopic cryostat according to claim 1, characterized in that: The tube legs are concentric structures, from the outside to the inside, they are the shell and the core; The outer shell of the tube leg is connected to the vacuum shell; The shell and the insert are made of stainless steel; The interior of the shell and the interior of the vacuum shell are a common vacuum environment; The insert is a hollow structure with a welded bellows connection in the middle; The ferrule is gold-plated oxygen-free copper about 3-5 cm away from the sample holder and is tightly connected to the sample holder.

6. A microscopic cryostat according to claim 1, characterized in that: The liquid inlet is connected to an external cold source, and the coldness of the refrigerant reaches the sample holder through the insert of the tube leg; the heater is a ring structure, wrapping the outer shell and the air outlet of the tube leg; The gas outlet is connected to the interior of the plug core to discharge the vaporized refrigerant gas; The vacuum port is connected to an external pump set.

7. A microscopic cryostat according to claim 1, characterized in that: The electrical connector is internally connected to the thermostat's internal thermometer and heater leads, and externally connected to a temperature controller.

8. A microscopic cryostat according to claim 1, characterized in that: The extended cold finger is located in the center of the entire thermostat and is made of gold-plated oxygen-free copper; The sample holder is fixed on an extended cold finger made of gold-plated oxygen-free copper.

9. A microscopic cryostat according to claim 8, characterized in that: The centers of the top cover window of the vacuum housing, the sample holder, the extended cold finger and the sample holder are on the same straight line.

10. A microscopic cryostat according to claim 1, characterized in that: The support base is fixed to the optical table and supports the entire cryostat.

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