Variable cold diaphragm infrared detector test Dewar structure

Abstract

The invention discloses a variable cold diaphragm infrared detector testing Dewar structure which is composed of a Dewar shell, a cold shield assembly, a rotating device and a cold head. The cold shield assembly is positioned above the inner side of the Dewar shell, is adhered above the substrate of the cold head and is used for reducing stray radiation; the rotating device is arranged on a lead ring flange of the Dewar shell, extends to the upper part of the cold shield part and is used for controlling and changing the aperture size of the cold diaphragm of the detector; the cold head structure is located below the cold screen assembly. Through the design of the ultrasonic motor rotating device, the aperture size of the cold diaphragm can be accurately controlled in real time. The ultrasonic motor rotating device is compact and simple in structure and can stably operate for a long time under the low-temperature vacuum condition. The design of the truss and the base plate can reduce the requirements for the machining precision and the assembly precision, reduce the heat leakage at the position of the diaphragm and the overall thermal load of the Dewar, and accelerate the starting speed of the detector.

Description

Technical Field

[0001] The present invention discloses a variable cold stop infrared detector test dewar structure, which specifically relates to the fields of refrigerated infrared detectors and variable cold stops. Background Art

[0002] The cold stop size is a key parameter of the detector dewar assembly. The cold stop size of traditional detectors cannot be dynamically changed, which causes problems such as low aperture utilization rate and poor stray radiation suppression effect for the zoom optical system. The variable F-number optical system with a variable cold stop can effectively solve the above problems. For refrigerated variable cold stop infrared detectors, a variable cold stop structure that can operate smoothly in a low-temperature environment needs to be built, and at the same time, precise control of the cold stop aperture can be achieved. The lead screw and the stepper motor adopt an integrated structure, effectively reducing the size of the entire electro-controlled cold stop device, and its structure is compact.

[0003] CN202886705U discloses a variable cold stop dewar. This structure drives the transmission gear through a stepper motor, adjusts the cold stop aperture through gear meshing, and uses an adiabatic plate to isolate the motor from the low-temperature environment; CN203455532U discloses a device for adjusting the variable cold stop aperture. This structure uses a ring-shaped rheostat to feedback the cold stop aperture in real time, and drives the cold stop aperture adjustment through an ultrasonic motor, ensuring the linear motion, positioning accuracy, and stability of the arc-shaped cold stop.

[0004] However, the above stepper motor and ring-shaped rheostat have insufficient reliability in a low-temperature environment, and there are problems such as low temperature may cause the performance of the device to decline or fail. At the same time, the structures adopted are relatively complex and large in size, making it difficult to meet the requirements of dewar miniaturization and having a high maintenance cost; in addition, the influence of factors such as the deformation of the assembly structure caused by the difference in thermal expansion coefficient and the thermal load and heat leakage of the entire dewar is not considered. Summary of the Invention

[0005] To meet the requirements of variable cold stop aperture size of infrared detectors, continuous operation in a low-temperature vacuum environment, and dewar miniaturization, aiming at the deficiencies in the background art, the technical problems to be solved by the present invention are as follows:

[0006] (1) Provide a small cold stop drive device that can continuously operate in a low-temperature vacuum environment;

[0007] (2) Provide a cold stop drive device with a small thermal load and adiabatic function.

[0008] The technical solution of the present invention is as follows:

[0009] A variable cold stop infrared detector test dewar structure, which adopts a detachable window structure, meets the requirements of repeated disassembly and assembly of the test dewar; the truss and backing plate in the rotating device are connected by springs to achieve the assembly of the cold stop with a certain pre-pressure; finally, the rotating device is driven by an ultrasonic motor to realize the function of adjustable aperture size of the detector cold stop.

[0010] The dewar structure of the present invention is composed of a dewar outer shell 1, a cold shield assembly 2, a rotating device 3, and a cold head 4. The dewar outer shell 1 is used to enclose the cold shield assembly 2, the rotating device 3, the cold head 4 and other remaining components, providing protection and a vacuum environment for the whole dewar; the cold shield assembly 2 is located above the inner side of the dewar outer shell 1 and is pasted above the substrate 43 of the cold head 4, playing a role in reducing stray radiation; the rotating device 3 is installed on the lead ring flange 21 of the dewar outer shell 4 and extends above the cold shield component 2, which can control and change the aperture size of the detector cold stop; the cold head structure 4 is located below the cold shield assembly 2 and is the core component for detector imaging.

[0011] The specific structural features of the present invention are as follows:

[0012] The dewar outer shell 1 is composed of an upper window seat 11, a lower window seat 12, a window pane 13, a sealing ring 14, a motor support 15, a bracket 16, and a lead ring flange 17. The window pane 13 is fixed in the groove of the upper window seat 11 by brazing; six threaded holes are evenly distributed circumferentially on the upper window seat 11, and the specifications and depths of each threaded hole are the same; the upper window seat 11 and the lower window seat 12 are connected by bolts, and the sealing ring 14 is located inside the threaded holes of the lower window seat 12, which can increase the vacuum degree of the sealed dewar; the lead ring flange 17 is located below the lower window seat 12, providing mechanical installation support for each component of the dewar; the motor support 15 and the bracket 16 are welded on the lead ring flange 17, providing mechanical installation support for the outer ring 32 and the ultrasonic motor 31 respectively.

[0013] The cold shield assembly 2 is composed of a cold shield outer shell 21, a filter 22, a first and second baffle 3, and a second baffle 24, which can reduce the entry of stray light into the chip 44. The inner surface of the cold shield outer shell 9 is blackened, the first baffle 11 and the second baffle 12 are respectively glued to the transition of the cold shield outer shell 10, and the filter 11 is located in the middle layer of the cold shield and is adhesively connected to the lower surface of the first baffle 11.

[0014] The rotating device 3 is located outside the cold shield assembly 2. The two are on the same axis and are composed of an ultrasonic motor 31, an outer ring 32, an inner ring 33, a truss 34, a diaphragm 35, and a backing plate 36. The ultrasonic motor 31 is installed on the motor support 15 by bolt connection to provide a driving torque for the rotating device 3. The outer ring 32 is adhesively installed on the bracket 16. The inner ring 33 is located inside the outer ring 32. The truss 34 is adhesively installed above the inner ring 33. All three are part of the transmission structure. The rotating device 3 contains a total of 10 diaphragms 35 located above the cold shield. The pins on both sides of each diaphragm 35 are respectively connected to the upper end of the cold shield housing 21 and the lower end of the backing plate 36. The rotating device 3 changes the cold aperture size by the movement of the diaphragm 35.

[0015] The ultrasonic motor 31 is located above the motor support 15 outside the rotating device 3, and the two are connected by bolts. The ultrasonic motor 31 is composed of a piezoelectric ceramic sheet 311, a stator base 312, an adjusting screw 313, an ultrasonic motor driving foot 314, and a base 315. The piezoelectric ceramic sheet 311 will generate a driving force under a certain voltage due to the inverse piezoelectric effect. The ultrasonic motor driving foot 314 is in vertical contact with the inner ring 33 and can transmit the torque generated by the piezoelectric ceramic sheet 311 to the inner ring 33. The adjusting screws 313 are located on both sides of the stator base 312 and can adjust the pre-tightening force between the ultrasonic motor driving foot 314 and the inner ring 33, enabling the ultrasonic motor to better drive the inner ring 33 to rotate. The assembled ultrasonic motor device is bolted to the motor support 15 through a through-hole, and the adjusting screw 313 is used to ensure that the ultrasonic motor driving foot 314 and the inner ring 33 are in vertical and close contact with a suitable pre-tightening force.

[0016] The outer ring 32 is a circular ring structure and is adhesively fixed above the bracket 16. There is a pair of pin holes and a pair of rectangular slots on the outside, which are diagonally distributed. The pin holes can insert pins to connect the inner and outer rings, and the rectangular slots facilitate the motor to pass through the outer ring to directly drive the inner ring to rotate.

[0017] The inner ring 33 is a circular ring structure. There is a guide groove on the outside of the circular ring for connection with the outer ring through a pin. When the motor drives the inner ring to rotate, the pins on both sides friction circumferentially in the guide groove of the inner ring, restricting the axial movement of the inner ring.

[0018] The diaphragm 35 is composed of a metal sheet 351, a movable pin 352, and a fixed pin 353. The movable pin 352 and the fixed pin 353 are respectively installed on both sides of the metal sheet 351 and in opposite installation directions. The three are combined by adhesive bonding. The fixed pin 353 of the diaphragm 35 is placed in the pin hole of the cold shield housing 21, and 10 diaphragms 35 are arranged in sequence along the circumferential direction of the cold shield opening.

[0019] The backing plate 36 is in an overall annular structure and is installed above the diaphragm plate 35. There are 10 pin guide grooves evenly distributed at its inner circle, which can cooperate with the movable pins 352 of the diaphragm plate 35 to guide the movable pins 32 of the diaphragm plate to move in and out along the pin guide grooves, so as to realize the change of the diaphragm aperture; on its upper surface, 10 circular grooves are evenly distributed at both sides of the pin holes according to the circumferential angle, which are used for bonding the lower ends of the springs connected to the truss. The springs apply a certain pressure to the backing plate 36 and the diaphragm plate 35, which can improve the assembly reliability and reduce the contact thermal resistance; the material used for the backing plate 36 is similar to the material property of the diaphragm plate 35, which can effectively reduce the problem of assembly structure deformation caused by temperature change.

[0020] The truss 34 is composed of an upper ring 341, a lower ring 342 and 6 connecting ribs 343. The upper ring 341 and the lower ring 342 are coaxial. The whole part is integrally formed and hollowed out around, which plays the role of reducing the cold loss, transmitting torque and providing a pre-pressure for the backing plate. There are 10 circular grooves on the lower surface of the upper ring 341 that correspond one by one to the circular grooves of the backing plate 36, which are used for bonding the upper ends of the springs connected to the backing plate. The upper ring 341 compresses and drives the springs to provide a certain pre-pressure and torque for the backing plate 36; the connecting ribs 343 are used to connect the upper ring 341 and the lower ring 342 of the truss, and are spiral, which can increase the heat transfer path, thereby improving the adiabatic ability of the truss 34; the lower ring 342 is connected to the inner ring 33 through an inverted L-shaped step and is connected with glue. The coaxiality of the two needs to be ensured during the assembly process.

[0021] The cold head structure 4 includes a bottom plate group 41, a transition block 42, a substrate 43 and a chip 44. Among them, the bottom plate group 22 mainly serves as a platform for supporting the chip group and the cold screen structure, and at the same time transfers cold to the chip and the cold screen components; the transition block 23 is located above the bottom plate group 22, and its main function is to relieve the thermal mismatch problem between the bottom plate group 22, the substrate 43 and the chip 44 due to different thermal expansion coefficients of various materials; the substrate 43 is located above the transition block 42 and is a reference plane for bonding the chip 44 and the cold screen assembly 2, and can connect the chip 44 and the external circuit; the chip 44 is bonded in the center of the substrate 43. The chip receives the electrical signal generated by the detection target and conducts signal interaction through the substrate.

[0022] The beneficial effects of the present invention include:

[0023] The present invention provides a variable cold diaphragm test dewar. Through the design of the ultrasonic motor rotating device, the size of the cold diaphragm aperture can be accurately controlled in real time. The ultrasonic motor rotating device has a compact and simple structure and can operate stably for a long time under low-temperature vacuum conditions. The design of the truss and the backing plate can reduce the requirements for machining accuracy and assembly accuracy, reduce the heat leakage at the diaphragm plate and the overall heat load of the dewar, and accelerate the start-up speed of the detector. Description of the Drawings

[0024] Figure 1 : Schematic diagram of the variable cold diaphragm test dewar structure.

[0025] Figure 2 : Schematic diagram of the ultrasonic motor drive device structure.

[0026] Figure 3 : Schematic diagram of the outer ring structure.

[0027] Figure 4 : Schematic diagram of the inner ring structure.

[0028] Figure 5 : Schematic diagram of the diaphragm structure.

[0029] Figure 6 : Schematic diagram of the backing plate structure.

[0030] Figure 7 : Schematic diagram of the truss structure.

[0031] In the figure:

[0032] 1 - Dewar shell, 2 - Cold shield assembly, 3 - Rotating device, 4 - Cold head;

[0033] 11 - Upper window seat, 12 - Lower window seat, 13 - Window piece, 14 - Sealing ring, 15 - Motor bearing seat, 16 - Bracket, 17 - Lead ring flange;

[0034] 21 - Cold shield shell, 22 - Filter, 23 - First baffle, 24 - Second baffle;

[0035] 31 - Ultrasonic motor, 32 - Outer ring, 33 - Inner ring, 34 - Truss, 35 - Diaphragm, 36 - Backing plate;

[0036] 41 - Negative film group, 42 - Transition block, 43 - Substrate, 44 - Chip;

[0037] 311 - Piezoelectric ceramic sheet, 312 - Stator base, 313 - Adjusting screw, 314 - Ultrasonic motor drive foot, 315 - Base;

[0038] 341 - Upper ring, 342 - Lower ring, 343 - Connecting rib. Specific implementation mode

[0039] Such as Figure 1As shown in the figure, a variable cold diaphragm infrared detector test Dewar structure is composed of a Dewar housing 1, a cold screen assembly 2, a rotating device 3, and a cold head 4. The Dewar housing 1 wraps the other components inside, providing protection and a vacuum environment for the whole Dewar. The cold screen assembly 2 is located above the inner side of the Dewar housing 1 and is pasted above the substrate 43 of the cold head 4, playing a role in reducing stray radiation. The rotating device 3 is installed on the lead ring flange 21 of the Dewar housing 4 and extends above the cold screen component 2, which can control and change the aperture size of the detector's cold diaphragm. The cold head structure 4 is located below the cold screen assembly 2 and is the core component for detector imaging.

[0040] The specific structural features of the present invention are as follows:

[0041] The Dewar housing 1 is composed of an upper window seat 11, a lower window seat 12, a window pane 13, a sealing ring 14, a motor support 15, a bracket 16, and a lead ring flange 17. The window pane 13 is fixed in the groove of the upper window seat 11 by brazing. The upper window seat 11 is circumferentially provided with 6 threaded holes with the same specifications and the same hole depth. The upper window seat 11 and the lower window seat 12 are connected by bolts. The sealing ring 14 is located inside the threaded holes of the lower window seat 12, which can increase the vacuum degree of the sealed Dewar. The lead ring flange 17 is located below the lower window seat 12, providing mechanical installation support for each component of the Dewar. The motor support 15 and the bracket 16 are welded on the lead ring flange 17, respectively providing mechanical installation support for the outer ring 32 and the ultrasonic motor 31.

[0042] The cold screen assembly 2 is composed of a cold screen housing 21, a filter 22, a first baffle 3, and a second baffle 24, which can reduce the entry of stray light into the chip 44. The inner surface of the cold screen housing 9 is blackened. The first baffle 11 and the second baffle 12 are respectively glued to the transition of the cold screen housing 10. The filter 11 is located in the middle layer of the cold screen and is adhesively connected to the lower surface of the first baffle 11.

[0043] The rotating device 3 is located outside the cold screen assembly 2 and they are on the same axis. It is composed of an ultrasonic motor 31, an outer ring 32, an inner ring 33, a truss 34, a diaphragm 35, and a backing plate 36. The ultrasonic motor 31 is installed on the motor support 15 by bolt connection, providing driving torque for the rotating device 3. The outer ring 32 is adhesively installed on the bracket 16. The inner ring 33 is located inside the outer ring 32. The truss 34 is adhesively installed above the inner ring 33, and the three are all part of the transmission structure. The rotating device 3 contains a total of 10 diaphragms 35 located above the cold screen. The pins on both sides of each diaphragm 35 are respectively connected to the upper end of the cold screen housing 21 and the lower end of the backing plate 36. The rotating device 3 changes the aperture size of the cold diaphragm by the movement of the diaphragm 35.

[0044] The structure of the ultrasonic motor 31 is as shown in the appendix Figure 2As shown, above the motor pedestal 15 located outside the rotating device 3, the two are connected by bolts. The ultrasonic motor 31 is composed of a piezoelectric ceramic sheet 311, a stator base 312, an adjusting screw 313, an ultrasonic motor driving foot 314, and a base 315. The piezoelectric ceramic sheet 311 will generate a driving force under a certain voltage due to the inverse piezoelectric effect; the ultrasonic motor driving foot 314 is in vertical contact with the inner ring 33, and it can transmit the torque generated by the piezoelectric ceramic sheet 311 to the inner ring 33; the adjusting screw 313 is located on both sides of the stator base 312, which can play a role in adjusting the pre-tightening force between the ultrasonic motor driving foot 314 and the inner ring 33, so that the ultrasonic motor can better drive the inner ring 33 to rotate. The assembled ultrasonic motor device is bolted to the motor pedestal 15 through a through hole, and the adjusting screw 313 is used to ensure that the ultrasonic motor driving foot 314 and the inner ring 33 are in vertical and close contact and have an appropriate pre-tightening force.

[0045] The structure of the outer ring 32 is as shown in the appendix Figure 3 As shown, it is a circular ring structure, which is fixed above the bracket 16 by gluing. There is a pair of pin holes and a pair of rectangular grooves on the outside, which are distributed diagonally. The pin holes can insert pins to connect the inner ring and the outer ring, and the rectangular grooves facilitate the motor to pass through the outer ring and directly drive the inner ring to rotate.

[0046] The structure of the inner ring 33 is as shown in the appendix Figure 4 As shown, it is a circular ring structure. There is a guide groove on the outside of the circular ring for connecting with the outer ring through a pin. When the motor drives the inner ring to rotate, the pins on both sides friction circumferentially in the guide groove of the inner ring, restricting the axial movement of the inner ring.

[0047] The structure of the aperture stop 35 is as shown in the appendix Figure 5 As shown, it is composed of a metal sheet 351, a movable pin 352, and a fixed pin 353. The movable pin 352 and the fixed pin 353 are respectively installed on both sides of the metal sheet 351, and the installation directions are opposite. The three are combined by gluing. The fixed pin 353 of the aperture stop 35 is placed in the pin hole of the cold shield housing 21, and 10 aperture stops 35 are arranged in sequence along the circumferential direction of the cold shield opening.

[0048] The structure of the spacer 36 is as shown in the appendix Figure 6 As shown, its overall is a circular ring structure, installed above the aperture stop 35. There are 10 pin guide grooves evenly distributed at its inner circle, which can cooperate with the movable pin 352 of the aperture stop 35 to guide the movable pin 32 of the aperture stop to move in and out along the pin guide groove, and the aperture of the aperture stop can be changed; there are 10 circular grooves evenly distributed on its upper surface on both sides of the pin hole according to the circumferential angle, which are used for bonding the lower ends of the springs connected to the truss. The springs apply a certain pressure to the spacer 36 and the aperture stop 35, which can improve the assembly reliability and reduce the contact thermal resistance; the material used for the spacer 36 is similar to the material property of the aperture stop 35, which can effectively reduce the deformation problem of the assembly structure caused by temperature change.

[0049] The structure of the truss 34 is as follows Figure 7 shown, which is composed of an upper ring 341, a lower ring 342 and six connecting ribs 343. The upper ring 341 and the lower ring 342 are kept coaxial. The whole part is integrally formed with a hollow around it, which plays the role of reducing the cold loss, transmitting torque and providing a pre-pressure for the backing plate. There are 10 circular grooves on the lower surface of the upper ring 341 that correspond one by one to the circular grooves of the backing plate 36, which are used to bond the upper ends of the springs connected to the backing plate. The upper ring 341 compresses and drives the springs to provide a certain pre-pressure and torque for the backing plate 36; the connecting ribs 343 are used to connect the upper ring 341 of the truss and the lower ring 342 of the truss, and are spiral, which can increase the heat transfer path, thereby improving the heat insulation ability of the truss 34; the lower ring 342 is matched with the inner ring 33 through an inverted L-shaped step and is connected with glue. The coaxiality of the two needs to be ensured during the assembly process.

[0050] The cold head structure 4 includes a bottom plate group 41, a transition block 42, a substrate 43 and a chip 44. Among them, the bottom plate group 22 mainly serves as a platform for supporting the chip group and the cold screen structure, and at the same time transmits cold to the chip and the cold screen components; the transition block 23 is located above the bottom plate group 22, and its main function is to relieve the thermal mismatch problem caused by different thermal expansion coefficients of the materials among the bottom plate group 22, the substrate 43 and the chip 44; the substrate 43 is located above the transition block 42 and is a reference plane for bonding the chip 44 and the cold screen assembly 2, and can connect the chip 44 and the external circuit; the chip 44 is bonded in the center of the substrate 43. The chip receives the electrical signal generated by the detection target and conducts signal interaction through the substrate.

Claims

1. A variable cold aperture infrared detector test dewar structure, characterized in that, The Dewar structure is composed of a Dewar outer shell (1), a cold shield assembly (2), a rotating device (3), and a cold head (4); the cold shield assembly (2) is located above the inner side of the Dewar outer shell (1) and is pasted above the substrate (43) of the cold head (4) for reducing stray radiation; the rotating device (3) is installed on the lead ring flange (21) of the Dewar outer shell (4) and extends above the cold shield component (2) for controlling and changing the aperture size of the detector cold aperture; the cold head structure (4) is located below the cold shield assembly (2).

2. The Dewar structure according to claim 1, characterized in that: The Dewar outer shell (1) is composed of an upper window seat (11), a lower window seat (12), a window pane (13), a sealing ring (14), a motor bearing seat (15), a bracket (16), and a lead ring flange (17); The window pane (13) is fixed in the groove of the upper window seat (11) by brazing; several threaded holes are evenly distributed circumferentially on the upper window seat (11); the upper window seat (11) and the lower window seat (12) are connected by bolts, and the sealing ring (14) is located inside the screw holes of the lower window seat (12); the lead ring flange (17) is located below the lower window seat (12); the motor bearing seat (15) and the bracket (16) are welded on the lead ring flange (17) to provide mechanical installation supports for the outer ring (32) and the ultrasonic motor (31) respectively.

3. The Dewar structure according to claim 1, characterized in that: The cold shield assembly (2) is composed of a cold shield outer shell (21), a filter (22), a first baffle (23), and a second baffle (24); the inner surface of the cold shield outer shell (9) is blackened, the first baffle (11) and the second baffle (12) are respectively glued to the transition of the cold shield outer shell (10), and the filter (11) is located in the middle layer of the cold shield and is adhesively connected to the lower surface of the first baffle (11).

4. The Dewar structure according to claim 1, characterized in that: The rotating device (3) is located outside the cold shield assembly (2), and the two are on the same axis. It is composed of an ultrasonic motor (31), an outer ring (32), an inner ring (33), a truss (34), a diaphragm (35), and a backing plate (36); the ultrasonic motor (31) is installed on the motor bearing seat (15) outside the rotating device (3) by bolt connection to provide a driving torque for the rotating device (3); the outer ring (32) is adhesively installed on the bracket (16), the inner ring (33) is located inside the outer ring (32), and the truss (34) is adhesively installed above the inner ring (33), and the three are all part of the transmission structure.

5. The Dewar structure according to claim 4, characterized in that: The rotating device (3) contains a total of 10 diaphragms (35). The pins on both sides of each diaphragm (35) are respectively connected to the upper end of the cold shield outer shell (21) and the lower end of the backing plate (36). The rotating device (3) changes the aperture size of the cold aperture through the movement of the diaphragms (35).

6. The Dewar structure according to claim 1, characterized in that: The ultrasonic motor (31) is located above the motor bearing seat (15) outside the rotating device (3), and the two are connected by bolts; The ultrasonic motor (31) is composed of a piezoelectric ceramic sheet (311), a stator base (312), an adjusting screw (313), an ultrasonic motor driving foot (314), and a base (315); The piezoelectric ceramic sheet (311) will generate a driving force under a certain voltage due to the inverse piezoelectric effect; the ultrasonic motor driving foot (314) is in vertical contact with the inner ring (33), and it can transfer the torque generated by the piezoelectric ceramic sheet (311) to the inner ring (33); the adjusting screw (313) is located on both sides of the stator base (312), which can adjust the pre-tightening force between the ultrasonic motor driving foot (314) and the inner ring (33), enabling the ultrasonic motor to better drive the inner ring (33) to rotate; the assembled ultrasonic motor device is bolted to the motor socket (15) through a through-hole, and the adjusting screw (313) is used to ensure that the ultrasonic motor driving foot (314) and the inner ring (33) are in vertical and close contact with a suitable pre-tightening force.

7. The Dewar structure according to claim 1, characterized in that: The outer ring (32) is a circular ring structure, which is fixed above the bracket (16) by gluing. There are a pair of pin holes and a pair of rectangular grooves on the outside, which are distributed diagonally. The pin holes can insert pins to connect the inner ring and the outer ring, and the rectangular grooves facilitate the motor to directly drive the inner ring to rotate through the outer ring; The inner ring (33) is a circular ring structure. There is a guide groove on the outside of the circular ring for connection with the outer ring through a pin; when the motor drives the inner ring to rotate, the pins on both sides friction circumferentially in the inner ring guide groove, restricting the axial movement of the inner ring.

8. The Dewar structure according to claim 5, wherein: The aperture stop (35) is composed of a metal sheet (351), a movable pin (352), and a fixed pin (353). The movable pin (352) and the fixed pin (353) are respectively installed on both sides of the metal sheet (351), and the installation directions are opposite. The three are combined by gluing; the fixed pin (353) of the aperture stop (35) is placed in the pin hole of the cold shield housing (21), and 10 aperture stops (35) are arranged in sequence along the circumferential direction of the cold shield opening; The backing plate (36) is a circular ring structure as a whole, installed above the aperture stop (35). There are 10 pin guide grooves evenly distributed at its inner circle, which can cooperate with the movable pins (352) of the aperture stop (35) to guide the movable pins (32) of the aperture stop to move in and out along the pin guide grooves, realizing the change of the aperture diameter; there are 10 circular grooves evenly distributed at the circumferential angle on both sides of the pin hole on its upper surface, which are used to bond the lower ends of the springs connected to the truss. The springs apply a certain pressure to the backing plate (36) and the aperture stop (35), which can improve the assembly reliability and reduce the contact thermal resistance; the material used for the backing plate (36) is similar to the material property of the aperture stop (35), which can effectively reduce the deformation problem of the assembly structure caused by temperature change; The truss (34) consists of an upper ring (341), a lower ring (342), and six connecting ribs (343). The upper ring (341) and the lower ring (342) are coaxial. The whole part is integrally formed with a hollow around it, which plays a role in reducing cold loss, transmitting torque, and providing pre-pressure for the backing plate. Among them, there are 10 circular grooves on the lower surface of the upper ring (341) corresponding one by one to the circular grooves of the backing plate (36), which are used to bond the upper ends of the springs connected to the backing plate. The upper ring (341) compresses and drives the springs to provide a certain pre-pressure and torque for the backing plate (36). The connecting ribs (343) are used to connect the upper ring (341) and the lower ring (342) of the truss, and are spiral, which can increase the heat transfer path, thereby improving the adiabatic ability of the truss (34). The lower ring (342) is matched with the inner ring (33) through an inverted L-shaped step, and is connected with glue. The coaxiality of the two must be ensured during the assembly process.

9. The Dewar structure according to claim 1, wherein: The cold head structure (4) includes a bottom plate group (41), a transition block (42), a substrate (43), and a chip (44); Among them, the bottom plate group (22) mainly serves as a platform for supporting the chip group and the cold screen structure, and at the same time transmits cold to the chip and the cold screen components. The transition block (23) is located above the bottom plate group (22), and its main function is to relieve the thermal mismatch problem caused by different thermal expansion coefficients of various materials among the bottom plate group (22), the substrate (43), and the chip (44). The substrate (43) is located above the transition block (42), and is a reference plane for bonding the chip (44) and the cold screen assembly (2), and can connect the chip (44) and the external circuit. The chip (44) is bonded in the center of the substrate (43). The chip receives the electrical signal generated by the detection target and conducts signal interaction through the substrate.

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