A low temperature imaging test device for infrared detector micro-dewar packaging before welding

Abstract

The invention provides a low-temperature imaging test device before the packaging welding of an infrared detector micro-dewar, belonging to the technical field of infrared detector testing; the invention solves the problems of poor sealing and insufficient refrigeration effect of equipment used in existing infrared detectors; the invention comprises an imaging test platform and a liquid nitrogen dewar, wherein the imaging test platform is connected to the liquid nitrogen dewar through an adapter; the imaging test platform comprises a bottom support structure for installing the micro-dewar, a vacuum cover bottom plate is fixed on the bottom support structure, a middle-test dewar window seat connecting seat is installed on the vacuum cover bottom plate, and a first vacuum pumping port is opened on the vacuum cover bottom plate; a low-temperature sealing structure is arranged at the connection between the micro-dewar and the vacuum cover bottom plate; a liquid nitrogen direct-blowing cold head inside the liquid nitrogen dewar extends into the bottom support structure near the vacuum cover bottom plate; the invention is applied to the infrared detector micro-dewar before the last process welding.

Description

Technical Field

[0001] The invention provides a low-temperature imaging test device for an infrared detector micro-Dewar package before welding, belonging to the technical field of infrared detector testing. Background Art

[0002] In the process of chip imaging test performance before packaging the infrared detector's Dewar window seat, the existing technology mainly has the following problems: 1. Lack of chip imaging test before window seat packaging: In the current process, chips usually enter the micro-dewar packaging directly after completing performance testing in the medium-test dewar. This process is easily affected by external factors such as static electricity, resulting in chip damage. Even if companies with mature technology rely on experience to control risks, once uncontrollable problems occur, all high-cost dewars will be scrapped, seriously affecting production efficiency and causing huge economic losses.

[0003] 2. Poor sealing: Common low-temperature sealing structures use O-rings or PTFE gaskets to compress and seal from top to bottom. When applied to the Dewar window seat pre-packaging test fixture, the pressure of the tightening screws may damage the lead ring. If the side wall seal is used instead, it is difficult to ensure effective sealing due to the limited surface area of ​​the lead ring side wall. Sealing failure will cause a dynamic vacuum, causing the chip area to heat up and unable to be cooled by liquid nitrogen. It may also introduce external impurities, affecting the purity of the test environment and the accuracy of the results.

[0004] 3. Insufficient refrigeration effect: The refrigeration structure of the existing medium-test liquid nitrogen dewar relies on the copper column soaked in liquid nitrogen inserted into the cold finger to connect the cold head. According to the principle of heat transfer, this design increases heat transfer. For the imitation of the liquid nitrogen dewar originally used for the micro dewar, ANSYS analysis shows that the heat transfer process will cause a heat loss of about 20K. The insufficient refrigeration effect causes the internal temperature of the system to exceed 77K, affecting the consistency and stability of the test results. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a low-temperature imaging test device for infrared detector micro-Dewar packaging before welding, which can be used for performance testing of medium-wave, long-wave and very long-wave infrared detectors before Dewar packaging.

[0006] The technical solution adopted by the present invention is: a low-temperature imaging test device before welding of an infrared detector micro-Dewar package, comprising an imaging test platform and a liquid nitrogen Dewar, wherein the imaging test platform is connected to the liquid nitrogen Dewar through an adapter; The imaging test platform includes a bottom support structure for installing a micro-dewar, a vacuum cover bottom plate is fixed on the bottom support structure, a middle-measurement Dewar window seat connecting seat for connecting with a middle-measurement Dewar window seat is installed on the vacuum cover bottom plate, a first vacuum port is opened on the vacuum cover bottom plate for connecting with an external vacuum pump, and a first vacuum chamber is formed inside the vacuum cover during testing; A low temperature sealing structure is provided at the connection between the micro-Dewar and the bottom plate of the vacuum cover; The liquid nitrogen direct blowing cold head inside the liquid nitrogen dewar extends into the bottom supporting structure near the bottom plate of the vacuum cover.

[0007] Furthermore, the liquid nitrogen direct blowing cold head is arranged inside the cold finger liquid nitrogen pipe, and the cold finger liquid nitrogen pipe is fixedly connected to the bottom support structure through the cold finger base fixing piece.

[0008] Furthermore, an outer tube is fixed at the bottom of the cold finger base fixing part, vacuum liquid nitrogen is arranged between the outer tube and the cold finger liquid nitrogen tube, and a second vacuum port is opened on the outer tube. During the test, the second vacuum port is connected to an external vacuum pump and is always in a vacuum working state, so that the flow rate of the vacuum liquid nitrogen is accelerated.

[0009] Furthermore, the liquid nitrogen dewar comprises an outer cover and a liquid nitrogen dewar liner, and a second vacuum chamber is formed between the outer cover and the liquid nitrogen dewar liner through a third vacuum port arranged on the outer cover.

[0010] Furthermore, the sealing surface where the micro-Dewar is connected to the bottom plate of the vacuum cover is a hollow cylindrical metal frame, and the low-temperature sealing structure adopts a triple sealing design, including a first gasket, a first sealing O-ring and a second sealing O-ring, wherein the first sealing O-ring is arranged on the outer surface of the hollow cylindrical metal frame, the second sealing O-ring is arranged on the inner surface of the hollow cylindrical metal frame, and the first gasket is arranged on the upper surface of the hollow cylindrical metal frame.

[0011] Furthermore, a second gasket and a third gasket are respectively provided on the upper and lower sides of the outer tube.

[0012] Furthermore, the first gasket is made of polytetrafluoroethylene, and the first sealing O-ring and the second sealing O-ring are made of elastic material.

[0013] Furthermore, the outer surface of the outer cover is made of polyurethane foam material.

[0014] Furthermore, the outer surface of the liquid nitrogen Dewar inner tank adopts a composite structure of multiple layers of high-reflection films, and air gaps are arranged between each layer of the film.

[0015] Furthermore, an inner tank liquid nitrogen sealing interface is provided between the liquid nitrogen Dewar inner tank and the outer cover, and the cold finger liquid nitrogen pipe passes through the inner tank liquid nitrogen sealing interface.

[0016] The beneficial effects of the present invention compared with the prior art are as follows: 1. Add chip imaging test process before window seat packaging to reduce the risk of Dewar scrapping: By introducing the chip imaging test process before window seat packaging, the present invention effectively reduces the risk of chip damage caused by factors such as static electricity. In the traditional process, the chip directly enters the micro-dewar packaging after completing the performance test in the medium-test dewar. This process is extremely susceptible to external interference, causing irreversible chip damage. In this case, not only does the high-cost dewar face the risk of being scrapped (such problems have occurred many times), it will also seriously affect production efficiency and bring huge economic losses. By adding this key testing step, the present invention ensures the quality and stability of the chip before packaging, thereby significantly reducing the probability of the dewar being scrapped and improving overall production efficiency.

[0017] 2. Improve cooling efficiency, achieve rapid cooling, and enhance the overall performance of the system: The present invention greatly improves the cooling efficiency and achieves a faster cooling effect by optimizing the cooling structure. Traditional refrigeration methods usually use liquid nitrogen immersion or indirect cooling methods, which results in slow cooling speed and low efficiency. The present invention reduces the heat conduction distance by directly cooling the cold finger end by decompressing liquid nitrogen (according to the principle of heat conduction), and combines the design of providing a high pressure difference to increase the flow rate of liquid nitrogen with a vacuum pump to ensure that there is always full liquid nitrogen that has not completely evaporated into gas to contact the cold head. Under a low vacuum environment of E-3Pa, the temperature of liquid nitrogen is reduced to 65K. According to the principle of heat transfer, the heat transfer speed is accelerated, which further improves the cooling effect and makes the cooling faster. These improvement measures not only enhance the refrigeration effect, but also significantly improve the overall performance of the system, shorten the test time, and improve production efficiency.

[0018] 3. Improve the low-temperature sealing structure to ensure the long-term stability and reliability of the system: The present invention pays special attention to the optimization of the low-temperature sealing structure to ensure the long-term stability and reliability of the system in an extremely low-temperature environment. The low-temperature sealing structure in the prior art usually uses an O-ring or a polytetrafluoroethylene gasket to compress and seal from top to bottom. This method is prone to damage to the lead ring due to the pressure of the fastening screws, or the side wall sealing surface area is insufficient and fails. The present invention adopts a triple sealing structure for sealing the micro-dewar to be tested before welding, wherein the sealed surface is a hollow cylindrical metal frame, the inner surface is sealed with an O-ring (with an O-ring limiting groove), the outer surface is sealed with an O-ring (with an O-ring limiting groove), and the upper surface is sealed with a polytetrafluoroethylene gasket (with a limiting groove for a sealing gasket), ensuring that the sealing structure can still fit tightly at low temperatures to prevent leakage. This improved sealing structure can maintain good sealing performance in an extremely low-temperature environment, avoiding problems such as dynamic vacuum, temperature fluctuations and introduction of external impurities caused by sealing failure, thereby significantly improving the long-term stability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1It is a structural schematic diagram of the device of the present invention; Figure 2 for Figure 1 Sectional view of AA in the middle; Figure 3 A schematic diagram of the structure in which the tested dewar is installed on the device of the present invention; Figure 4 for Figure 3 Cross-sectional view of the middle BB; Figure 5 for Figure 2 Schematic diagram of the enlarged structure at C in the middle; In the figure: 1 is the imaging test platform, 2 is the liquid nitrogen dewar, 3 is the micro dewar, and 4 is the chip under test; 11 is a vacuum cover, 12 is a vacuum cover bottom plate, 13 is a bottom support structure, 14 is a low temperature sealing structure, 141 is a first gasket, 142 is a first sealing O-ring, 143 is a second sealing O-ring, 15 is a middle-side Dewar window seat connecting seat, 151 is a third sealing O-ring, 152 is a middle-side Dewar window seat, 16 is a first vacuum port, and 17 is a first vacuum chamber; 21 is a liquid nitrogen direct blowing cold head, 211 is a cold finger sealing ring, 212 is a cold finger base fixing part, 22 is a liquid nitrogen reflux space, 23 is a cold finger liquid nitrogen pipe, 231 is a second gasket, 232 is a third gasket, 24 is vacuum liquid nitrogen, 241 is a second vacuum pumping port, 242 is an external liquid nitrogen side seal, 251 is a pre-tightening device, 252 is an external vacuum side seal, 26 is an outer cover, 261 is an outer cover upper cover, 262 is an outer cover back cover, 27 is a second vacuum chamber, 28 is a liquid nitrogen Dewar liner, 281 is an inner liner upper cover, 282 is an inner liner back cover, 283 is an inner liner support, 284 is a metal sealing ring, 285 is an inner liner liquid nitrogen sealing interface, 286 is an inner liner side sealing ring, 287 is activated carbon, 29 is a third vacuum pumping port, and 30 is an outer layer tube. DETAILED DESCRIPTION

[0020] like Figures 1 to 5 As shown, the present invention provides a low-temperature imaging test device before the micro-dewar packaging welding of an infrared detector, which is used to perform a low-temperature imaging test on the chip before the last welding process of the micro-dewar of the infrared detector. The device mainly includes two parts, an imaging test platform 1 and a liquid nitrogen dewar 2, wherein the imaging test platform 1 is detachably connected to the liquid nitrogen dewar 2 through an adapter, and the liquid nitrogen dewar 2 is used to provide a low-temperature environment of 65K for the imaging test platform 1.

[0021] The imaging test platform 1 includes a bottom support structure 13 for installing the micro-dewar 3. The bottom support structure 13 is hollow inside and is used to place the micro-dewar 3. A vacuum cover bottom plate 12 is fixed on the bottom support structure 13. A middle-test Dewar window seat connecting seat 15 for threaded connection with the middle-test Dewar window seat 152 is installed on the vacuum cover bottom plate 12. A first vacuum port 16 is opened on the vacuum cover bottom plate 12 for connecting to an external vacuum pump. When testing, a first vacuum chamber 17 is formed inside the vacuum cover 11 to prevent heat convection and heat conduction, thereby ensuring the stability of the ambient temperature during testing.

[0022] like Figure 5 As shown, a low-temperature sealing structure 14 is provided at the part where the micro-dewar 3 is connected to the vacuum cover bottom plate 12. In view of the problem that the fragile structure cannot withstand pressure under low-temperature environment, the low-temperature sealing structure 14 of the present invention adopts a triple sealing design, which is used to seal the micro-dewar 3 to be tested before welding to ensure the airtightness between the micro-dewar 3 and the imaging test platform 1. The triple sealing design includes a first gasket 141, a first sealing O-ring 142 and a second sealing O-ring 143. The sealed surface is a hollow cylindrical metal frame. The first sealing O-ring 142 is used as an outer surface O-ring seal (with an O-ring limit groove), the second sealing O-ring 143 is used as an inner surface O-ring seal (with an O-ring limit groove), and the first gasket 141 is used as an upper surface seal (with a limit groove of a sealing gasket), and a polytetrafluoroethylene gasket is used; this design not only solves the process problem of high operating difficulty, but also ensures that the sealing ring can fit tightly under extreme low temperature conditions to prevent any possible leakage. Each layer of the sealing structure is optimized to ensure reliable sealing performance even under complex working conditions.

[0023] The window seat of the liquid nitrogen Dewar 2 is connected to the bottom of the imaging test platform 1 through an adapter, and the adapter can be matched with a suitable adapter according to the model of the liquid nitrogen Dewar 2 used; the liquid nitrogen Dewar 2 includes an outer cover 26 and a liquid nitrogen Dewar liner 28 located inside the outer cover 26, and the outer cover 26 is provided with an outer cover upper cover 261 and an outer cover rear cover 262, and the outer cover upper cover 261 is provided with a third vacuum port 29, and a vacuum pump is connected through the third vacuum port 29 to form a second vacuum chamber 27 between the outer cover 26 and the liquid nitrogen Dewar liner 28.

[0024] The liquid nitrogen Dewar liner 28 comprises an inner liner upper cover 281, an inner liner support 283 and an inner liner rear cover 282. The middle of the inner liner upper cover 281 is a liquid nitrogen filling inlet, which can be directly connected to the atmosphere or closed with a plug. When closed with a plug, a pressure difference can be generated with the second vacuum port 241 to make the liquid nitrogen flow in the forward direction; the inner liner support 283 is used to achieve a stable connection between the inner liner rear cover 282 and the outer cover rear cover 262, and an activated carbon cover is arranged on the outer side of the bottom end of the liquid nitrogen Dewar liner 28, and rod-shaped activated carbon 287 is placed inside the activated carbon cover to adsorb some impurities in the second vacuum chamber 27.

[0025] A liquid nitrogen direct blowing cold head 21 is arranged inside the liquid nitrogen Dewar inner tank 28, one end of the liquid nitrogen direct blowing cold head 21 is arranged inside the cold finger liquid nitrogen pipe 23, the space between the liquid nitrogen direct blowing cold head 21 and the cold finger liquid nitrogen pipe 23 is used as a liquid nitrogen reflux space 22, and the other end of the liquid nitrogen direct blowing cold head 21 passes through the bottom support structure 13 and extends into the bottom near the vacuum cover bottom plate 12; an inner tank liquid nitrogen sealing interface 285 is arranged between the liquid nitrogen Dewar inner tank 28 and the outer cover 26, the cold finger liquid nitrogen pipe 23 passes through the inner tank liquid nitrogen sealing interface 285, and an outer layer tube 30 is also arranged in the middle of the cold finger liquid nitrogen pipe 23, a second vacuum port 241 is opened on the outer layer tube 30, and the space between the outer layer tube 30 and the cold finger liquid nitrogen pipe 23 is filled with vacuum liquid nitrogen 24.

[0026] The structural design of the liquid nitrogen direct blowing cold head 21, the liquid nitrogen reflux space 22 and the second vacuum port 241 can realize the direct cooling of the cold finger end by the reduced pressure liquid nitrogen in a very narrow cold finger space, thereby achieving rapid cooling. The pressure difference generated by the vacuum pump significantly increases the circulation speed of the liquid nitrogen, further enhancing the cooling effect. This innovative design enables the cold finger to reach the required low temperature environment in a very short time, greatly improving the response speed and cooling efficiency of the system.

[0027] Furthermore, by connecting a vacuum pump through the second vacuum port 241, a high vacuum environment of E-3Pa level can be created, which can reduce the boiling point of liquid nitrogen to below 65K (according to the physical properties table of saturated nitrogen, liquid nitrogen can maintain 63.2K under a pressure of 0.012633MPa under the action of a dry pump). This ultra-low pressure environment not only ensures that liquid nitrogen boils at a lower temperature, but also reduces heat transfer, further optimizes the cooling effect, and ensures that the system operates stably under extremely low temperature conditions.

[0028] The outer layer of vacuum liquid nitrogen 24 covers the cold finger liquid nitrogen tube 23. The double-layer structure not only increases the contact area between the liquid nitrogen and the cold finger, but also effectively isolates the invasion of external heat, ensuring the efficiency and stability of the cooling process. In addition, this design also improves the overall insulation performance of the system and prolongs the maintenance time of the low temperature state.

[0029] The cold finger liquid nitrogen pipe 23 and the bottom support structure 13 are fixedly connected via a cold finger base fixing piece 212 , and a cold finger sealing ring 211 is also provided between the cold finger liquid nitrogen pipe 23 and the bottom support structure 13 to achieve sealing of the connection between the two.

[0030] An outer tube 30 is fixed at the bottom of the cold finger base fixing part 212, and a pre-tightening device 251 is fixed at the bottom of the outer tube 30. A second gasket 231 and a third gasket 232 are respectively arranged on the upper and lower sides of the outer tube 30, and both the second gasket 231 and the third gasket 232 are made of polytetrafluoroethylene gaskets to achieve effective sealing of the vacuum liquid nitrogen 24.

[0031] An outer vacuum side seal 252 is also installed inside the pre-tightening device 251 , and a metal sealing ring 284 and an inner tank side sealing ring 286 are also provided inside the inner tank liquid nitrogen sealing interface 285 to achieve effective sealing of the inner tank liquid nitrogen sealing interface 285 .

[0032] The gasket and sealing O-ring used in the triple seal design of the present invention are made of different materials. The sealing O-ring is made of rubber O-ring, which has good elasticity and adaptability, can maintain a certain flexibility at low temperatures, and ensure the initial sealing effect. The gasket is made of polytetrafluoroethylene (PTFE) gasket, which has excellent corrosion resistance and low friction coefficient, can maintain stable physical properties at extremely low temperatures, and further enhance the reliability and durability of the seal.

[0033] The above triple seal design has the following advantages: a. High reliability: Through the triple seal design and the application of multi-material composite seal rings, the present invention significantly improves the sealing reliability of the system. Even in an environment of extremely low temperature and high pressure difference, the low temperature seal structure 14 can still maintain a tight fit, effectively prevent leakage, and ensure the long-term stable operation of the system.

[0034] b. Easy to operate: Although a complex triple seal design is adopted, the invention is convenient and quick to operate in actual use, reducing the difficulty of actual operation. This improvement makes the sealing structure not only feasible in theory, but also easy to implement in actual application, reducing assembly time and cost.

[0035] c. Strong durability: The combination of rubber O-ring and PTFE gasket gives full play to the advantages of each material. The rubber O-ring provides the initial elastic seal, while PTFE enhances the durability and anti-aging performance of the seal. This combination design extends the service life of the seal and reduces maintenance frequency and cost.

[0036] d. Environmental adaptability: The low temperature sealing structure 14 is particularly suitable for low temperature environments, ensuring that good sealing performance can be maintained at extremely low temperatures. Whether it is aerospace, infrared detector testing or other application scenarios that require low temperature sealing, this design can provide reliable protection to ensure the normal operation of the system under extreme conditions.

[0037] The device of the present invention has a multiple refrigeration structure, the main parts of which are as follows: a. Multi-layer insulation material combination: The present invention adopts a combination design of multiple layers of thermal insulation materials to form a multiple thermal insulation structure to ensure the best thermal insulation effect in different temperature ranges. This multi-layer thermal insulation material not only improves the overall thermal insulation performance, but also enhances the stability and reliability of the system.

[0038] b. Vacuum sandwich design: A vacuum interlayer (i.e., the second vacuum chamber 27) is provided between the outer cover 26 (as the outer insulation layer) and the liquid nitrogen dewar liner 28 (as the inner insulation layer), further reducing heat transfer. The vacuum environment almost eliminates heat conduction and convection between gas molecules, significantly reducing the possibility of heat transfer from the outside. This design greatly improves the insulation efficiency of the entire system and ensures that the low-temperature environment can be maintained for a long time.

[0039] c. Inner layer high reflectivity aluminum foil composite structure: The outer surface of the liquid nitrogen dewar liner 28 adopts a multi-layer composite structure of 10 layers of high-reflectivity aluminum foil, with a tiny air gap between each layer. This design not only increases the reflection effect, but also effectively blocks the penetration of infrared radiation. Through the synergistic effect of multi-layer reflection and air gap, heat transfer is minimized to ensure the low-temperature stability of the internal environment.

[0040] The above-mentioned multiple refrigeration structure has the following advantages: a. Extreme insulation effect: Through the combination of multiple layers of insulation materials and the design of vacuum interlayer, the present invention achieves an extreme insulation effect. Even under extreme temperature difference conditions, the system can effectively block heat transfer and ensure that the internal environment is always maintained at the required low temperature state.

[0041] b. Highly efficient reflection and heat insulation: The multi-layer composite aluminum foil structure of the inner layer significantly enhances the reflection effect and effectively blocks the intrusion of infrared radiation. Combined with the low thermal conductivity of the high-density polyurethane foam of the outer layer, the system provides excellent thermal insulation performance at multiple levels and prolongs the maintenance time of the low temperature state.

[0042] c. Stable and reliable: The application of vacuum interlayer and high-density materials not only improves the insulation effect, but also enhances the stability and reliability of the system. Whether in static or dynamic environments, this multi-refrigeration structure can ensure a long-term stable low-temperature environment and is suitable for various high-precision applications.

[0043] d. Extend service life: By reducing heat transfer and enhancing thermal insulation, the present invention significantly reduces the thermal load of the system and reduces material aging and performance degradation caused by temperature fluctuations. This not only extends the service life of the system, but also reduces maintenance costs and frequency.

[0044] The principle of the present invention is as follows: fix the micro-dewar 3 in the bottom support structure 13 of the imaging test platform 1, make the cold finger of the micro-dewar 3 contact with the liquid nitrogen direct blowing cold head 21, then fix the vacuum cover 11, connect the first vacuum port 16 to the vacuum pump, evacuate the vacuum cover 11 into a vacuum environment, form a first vacuum chamber 17, and then seal the first vacuum port 16 with a plug; Connect the third vacuum port 29 to a vacuum pump, and create a vacuum environment between the outer cover 26 and the liquid nitrogen Dewar liner 28 to form a second vacuum chamber 27, and then seal the third vacuum port 29 with a plug; Open the liner upper cover 281, and introduce liquid nitrogen into the liquid nitrogen Dewar liner 28 through the liquid nitrogen filling inlet connected to the pipeline, and then seal the liquid nitrogen filling inlet with a plug, and cover the liner upper cover 281; The chip 4 to be tested is placed in the micro-dewar 3, the second vacuum port 241 is connected to a vacuum pump, and the vacuum pump connected to the second vacuum port 241 is started to generate a pressure difference between the space where the outer tube 30 and the cold finger liquid nitrogen tube 23 are located and the liquid nitrogen dewar liner 28, so that the liquid nitrogen flows forward, thereby forming a low-temperature environment of 65K inside the micro-dewar 3, so that the chip 4 to be tested is in a low-temperature environment, and then the performance of the chip 4 to be tested is tested by a black body radiation source. After the test is qualified, the micro-dewar 3 and the chip 4 to be tested are welded to obtain an infrared detector assembly. If the test fails, the chip 4 to be tested is removed, the unqualified part is repaired, and then it is put back into the device for testing.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-temperature imaging test device for infrared detector micro-dewar packaging before welding, characterized by: The imaging test platform (1) and the liquid nitrogen dewar (2) are connected to the liquid nitrogen dewar (2) via an adapter; The imaging test platform (1) includes a bottom support structure (13) for mounting a micro-dewar (3), a vacuum cover bottom plate (12) being fixed on the bottom support structure (13), a middle-measurement dewar window seat connecting seat (15) for connecting to a middle-measurement dewar window seat (152) being mounted on the vacuum cover bottom plate (12), a first vacuum port (16) being opened on the vacuum cover bottom plate (12) for connecting to an external vacuum pump, and a first vacuum chamber (17) being formed inside the vacuum cover (11) during testing; A low-temperature sealing structure (14) is provided at the connection between the micro-Dewar (3) and the vacuum cover bottom plate (12); The liquid nitrogen direct blowing cold head (21) inside the liquid nitrogen dewar (2) extends into the bottom support structure (13) near the vacuum cover bottom plate (12).

2. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 1, characterized in that: The liquid nitrogen direct blowing cold head (21) is arranged inside the cold finger liquid nitrogen tube (23), and the cold finger liquid nitrogen tube (23) is fixedly connected to the bottom support structure (13) via the cold finger base fixing piece (212).

3. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 2, characterized in that: An outer tube (30) is fixed at the bottom of the cold finger base fixing member (212), and vacuum liquid nitrogen (24) is arranged between the outer tube (30) and the cold finger liquid nitrogen tube (23). A second vacuum port (241) is opened on the outer tube (30). During the test, the second vacuum port (241) is connected to an external vacuum pump and is always in a vacuum working state, so that the flow rate of the vacuum liquid nitrogen (24) is accelerated.

4. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 1, characterized in that: The liquid nitrogen dewar (2) comprises an outer cover (26) and a liquid nitrogen dewar liner (28), and a second vacuum chamber (27) is formed between the outer cover (26) and the liquid nitrogen dewar liner (28) via a third vacuum port (29) provided on the outer cover (26).

5. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 1, characterized in that: The sealing surface where the micro-dewar (3) is connected to the vacuum cover bottom plate (12) is a hollow cylindrical metal frame. The low-temperature sealing structure (14) adopts a triple sealing design, including a first gasket (141), a first sealing O-ring (142) and a second sealing O-ring (143), wherein the first sealing O-ring (142) is arranged on the outer surface of the hollow cylindrical metal frame, the second sealing O-ring (143) is arranged on the inner surface of the hollow cylindrical metal frame, and the first gasket (141) is arranged on the upper surface of the hollow cylindrical metal frame.

6. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 3, characterized in that: A second gasket (231) and a third gasket (232) are respectively provided on the upper and lower sides of the outer tube (30).

7. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 5, characterized in that: The first gasket (141) is made of polytetrafluoroethylene, and the first sealing O-ring (142) and the second sealing O-ring (143) are made of elastic material.

8. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 4, characterized in that: The outer surface of the outer cover (26) is made of polyurethane foam material.

9. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 4, characterized in that: The outer surface of the liquid nitrogen Dewar liner (28) adopts a composite structure of multiple layers of high-reflection films, and air gaps are provided between each layer of film.

10. The low-temperature imaging test device for infrared detector micro-dewar package before welding according to claim 4, characterized in that: An inner liner liquid nitrogen sealing interface (285) is provided between the liquid nitrogen Dewar inner liner (28) and the outer cover (26), and the cold finger liquid nitrogen pipe (23) passes through the inner liner liquid nitrogen sealing interface (285).

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