Dewar shell structure for refrigeration type infrared detector

Abstract

The Dewar shell structure comprises a Dewar cold finger, a flange used for being coupled with a refrigerator is arranged at the lower end of the Dewar cold finger, a Dewar shell is welded to the interior of the upper end of the Dewar cold finger, and the outer surface of the Dewar shell and the outer surface of the Dewar cold finger are both provided with stripe-shaped protrusions. The outer part of the upper end of the Dewar cold finger is welded with the Dewar light window; in order to ensure the temperature controllability of the window seat part, the Dewar shell structure is optimized, on one hand, the heat dissipation area of the Dewar shell structure is increased through turning or carving to enhance the heat dissipation capacity of the Dewar shell, and on the other hand, the heat conduction heat flux is reduced by increasing the solid heat transfer distance from the Dewar top window seat to the assembly hot end; and the temperature rise of the shell and the top detection window seat of the Dewar can be effectively controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to a Dewar structure, in particular to a Dewar shell structure for a refrigeration type infrared detector. BACKGROUND

[0002] With the development of infrared technology, infrared detectors are widely used in military (border sea defense monitoring, missile seeker, satellite monitoring, etc.) and civilian fields (gas detection, forest protection, etc.), and refrigeration type infrared detectors, as high-end infrared detectors, are developing towards high performance, high reliability, large array, miniaturization, low power consumption, low cost, etc.

[0003] In the field of border sea defense monitoring, gas detection and forest protection, refrigeration type infrared detectors are required to ensure stable imaging for a long time. Refrigeration type infrared detectors mainly rely on small Stirling cryocoolers to provide stable ultra-low temperature (77K) working temperature for infrared detectors through Stirling cycle. A large amount of heat is inevitably generated during the long-term operation of the small Stirling cryocooler, and the heat is mainly concentrated in the compressor position of the cryocooler and the coupling position of the cryocooler and the Dewar cold finger. Due to the second law of thermodynamics, heat will spontaneously transfer from a high-temperature object to a low-temperature object, and the heat generated by the cryocooler will conduct along the Dewar shell, eventually causing the temperature of the Dewar window seat to rise. The rise in the temperature of the window seat not only increases the thermal radiation of the inner surface of the window seat to the Dewar cold head, increasing the power consumption of the detector, but also increases the response thermal noise, affecting the final imaging effect of the refrigeration type infrared detector. SUMMARY

[0004] The present application provides a Dewar shell structure for a refrigeration type infrared detector to overcome the defects of the prior art that the imaging effect of the infrared detector is deteriorated due to poor heat dissipation.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions:

[0006] The present application discloses a Dewar shell structure for a refrigeration type infrared detector, comprising a Dewar cold finger, the lower end of the Dewar cold finger is provided with a flange for coupling with a cryocooler, the upper end of the Dewar cold finger is internally welded with a Dewar shell, the outer surfaces of the Dewar shell and the Dewar cold finger are both in a stripe-shaped protrusion, and the upper end of the Dewar cold finger is externally welded with a Dewar optical window.

[0007] Further, an infrared detector chip is arranged in the top of the Dewar cold finger.

[0008] Further, a window welding reserved area is arranged at the joint of the Dewar optical window and the Dewar shell, and a cold finger welding reserved area is arranged at the joint of the Dewar shell and the Dewar cold finger.

[0009] Further, the light window welding reserved area comprises a shell welding light window reserved area at the upper end of the Dewar shell and a light window welding shell reserved area at the lower end of the Dewar light window.

[0010] Further, the cold finger welding reserved area comprises a shell welding cold finger reserved area at the lower end of the Dewar shell and a cold finger welding shell reserved area at the middle of the Dewar cold finger.

[0011] Further, the inner wall of the Dewar cold finger is a smooth barrel structure.

[0012] Further, the inner wall of the Dewar shell is a striped convex structure.

[0013] Further, the striped convex of the Dewar shell and the Dewar cold finger is used for increasing the heat dissipation area of each.

[0014] The present application has the following advantages: increasing the surface area of the Dewar shell, enhancing the heat dissipation capacity of the Dewar shell itself, reducing the temperature of the whole Dewar shell; increasing the heat conduction distance between the top light window of the Dewar and the coupling surface of the refrigerator and the cold finger, reducing the heat flux generated by the solid heat conduction of the pipe shell, reducing the heat received by the top light window, balancing the temperature of the Dewar shell; changing the structure of the Dewar to reduce the temperature of the Dewar shell, preventing the problem of the power consumption of the refrigeration type infrared detector rising due to the rising of the shell temperature to a certain extent, ensuring the stable and continuous long-time work of the detector; reducing the temperature of the top light window, reducing the self-thermal radiation of the top light window, reducing the thermal noise and stray light, improving the image stability of the refrigeration type infrared detector under the long-time working condition, and improving the long-term image quality of the refrigeration type infrared detector. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application and are used to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0016] Fig. 1 is a packaging structure schematic diagram of the present application;

[0017] Fig. 2 is a structure schematic diagram of the Dewar light window of the present application;

[0018] Fig. 3 is a structure schematic diagram of the Dewar shell of the present application;

[0019] Fig. 4 is a structure schematic diagram of the Dewar cold finger of the present application.

[0020] In the figure: 1, Dewar light window; 2, Dewar shell; 3, Dewar cold finger; 4, flange; 5, light window welding reserved area; 5-1, shell welding light window reserved area; 5-2, light window welding shell reserved area; 6, cold finger welding reserved area; 6-1, shell welding cold finger reserved area; 6-2, cold finger welding shell reserved area. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, it should be understood that the preferred embodiments described here are only used to illustrate and explain the present application, and are not used to limit the present application.

[0022] Example 1

[0023] As shown in the figure, a Dewar shell structure for a refrigeration type infrared detector includes a Dewar cold finger 3, the lower end of which is provided with a flange 4 for coupling with a refrigerator, and the upper end of which is internally welded with a Dewar shell 2, the outer surfaces of the Dewar shell 2 and the Dewar cold finger 3 are both in a strip-shaped protruding structure, and the upper end of the Dewar cold finger 3 is externally welded with a Dewar light window 1. Figs. 1-4

[0024] The top of the Dewar cold finger 3 is internally provided with an infrared detector chip.

[0025] The junction of the Dewar light window 1 and the Dewar shell 2 is provided with a light window welding reserved area 5, and the junction of the Dewar shell 2 and the Dewar cold finger 3 is provided with a cold finger welding reserved area 6.

[0026] The light window welding reserved area 5 includes a shell welding light window reserved area 5-1 at the upper end of the Dewar shell 2 and a light window welding shell reserved area 5-2 at the lower end of the Dewar light window 1.

[0027] The cold finger welding reserved area 6 includes a shell welding cold finger reserved area 6-1 at the lower end of the Dewar shell 2 and a cold finger welding shell reserved area 6-2 at the middle of the Dewar cold finger 3.

[0028] The inner wall of the Dewar cold finger 3 is in a smooth barrel structure.

[0029] The inner wall of the Dewar shell 2 is in a strip-shaped protruding structure.

[0030] The strip-shaped protruding structures of the Dewar shell 2 and the Dewar cold finger 3 are used to increase the heat dissipation area of each.

[0031] The bottom of the Dewar cold finger 3 is the main heat source position when the refrigerator works for a long time.

[0032] ​Process: Dewar light window 1 is a rotary structure, φ30mm black skin Kovar rod material, using rough turning, fine turning, fine grinding, cutting and other ways processing, Dewar light window 1 outer diameter 26mm, tolerance ±0.05mm, height 30mm, tolerance ±0.03mm, to ensure that the single wall thickness 1mm, the top reserved 15mm, take the positive tolerance 0 to +0.1mm opening to weld Dewar light window 1 for receiving infrared radiation, the bottom has a 1mm width of the welding reserved area for subsequent welding process.

[0033] Dewar shell 2 φ30mm black skin Kovar rod material, using rough turning machining method to complete the blank, the outer diameter is 26mm, the tolerance is ±0.05mm, the single side thickness of both sides is reserved 4mm, the inner and outer walls of Dewar shell 2 are processed by fine turning thread, the upper and lower outer walls are reserved 1.65mm width as the subsequent welding area, the thread is processed by G76 oblique cutting method, the major diameter is 25.4mm, the middle diameter is 23.368mm, the minor diameter is 21.335mm, the pitch is 3.1mm, and the tooth profile height is 2.033mm. The inner diameter thread is not reserved in size, and the same specification thread is directly turned from the bottom edge to ensure that the inner and outer surface threads are in the same position. Then the grinding machine is used to polish the inner and outer welding reserved positions to complete the processing.

[0034] Dewar cold finger 3 φ40mm black skin Kovar rod material, using rough turning, fine turning, honing and other ways, processing Dewar cold finger 3 to complete the blank, the outer wall top is reserved 1mm width as the subsequent welding area, the thread is processed by G76 oblique cutting method, the major diameter is 25.4mm, the middle diameter is 23.368mm, the minor diameter is 21.335mm, the pitch is 3.1mm, and the tooth profile height is 2.033mm, and then the grinding machine is used to polish the inner and outer welding reserved positions to complete the processing.

[0035] Using laser welding process, Dewar shell 2 and Dewar cold finger 3 are matched after processing, and the matching position is welded, the welding power is 3.3J, the weld penetration is greater than 0.6mm, the weld spot diameter is less than 0.8mm, and the weld is full and uniform. Then Dewar shell 2 and Dewar cold finger 3 welded are matched with the top Dewar light window 1, and the matching position is laser welded, the welding power is 3J, the weld penetration is greater than 0.6mm, the weld spot diameter is less than 0.8mm, and the weld is full and uniform. After welding, it is the packaged Dewar product.

[0036] It should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified or some technical features can be replaced by equivalent features by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the scope of the present application. The terms used in the description of the present application are only intended to describe the specific embodiments and are not intended to limit the exemplary embodiments according to the present application. In order to facilitate the description, the sizes of the parts shown in the drawings are not drawn in accordance with the actual proportional relationship. The technology, methods and devices known to those skilled in the related art can not be discussed in detail, but in appropriate cases, the technology, methods and devices should be considered as part of the authorized description. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0037] It should be noted that the terms "first", "second" and the like in the description and claims of the present application are used to distinguish similar objects, and are not intended to describe a particular order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second" and the like are generally a class, not limited to the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the objects before and after are in a "or" relationship.

[0038] It should be noted that in the description of the present application, the orientation or position relationship indicated by the orientation terms such as "front, rear, upper, lower, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" is generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without the opposite indication, these orientation terms do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the present application; the orientation terms "inner, outer" refer to the inner and outer of the contour of each part itself.

Claims

1. A Dewar shell structure for a cooled infrared detector, characterized in that, It includes a Dewar cold finger, the lower end of which is provided with a flange for coupling with a refrigeration unit, and the upper end of which is welded with a Dewar shell. The outer surfaces of both the Dewar shell and the Dewar cold finger are striped and raised. The upper outer end of the Dewar cold finger is welded to the Dewar light window.

2. The Dewar shell structure for a cooled infrared detector according to claim 1, characterized in that, The top of the Dewar cold finger has an infrared detector chip installed inside.

3. The Dewar shell structure for a cooled infrared detector according to claim 1, characterized in that, The connection between the Dewar window and the Dewar shell is provided with a reserved area for welding the window, and the connection between the Dewar shell and the Dewar cold finger is provided with a reserved area for welding the cold finger.

4. The Dewar shell structure for a cooled infrared detector according to claim 3, characterized in that, The light window welding reserved area includes a shell welding light window reserved area located at the upper end of the Dewar shell and a light window welding shell reserved area located at the lower end of the Dewar light window.

5. The Dewar shell structure for a cooled infrared detector according to claim 3, characterized in that, The cold finger welding reserved area includes a shell welding cold finger reserved area located at the lower end of the Dewar shell and a cold finger welding shell reserved area located in the middle of the Dewar cold finger.

6. The Dewar shell structure for a cooled infrared detector according to claim 1, characterized in that, The inner wall of the Dewar cold finger is a smooth cylindrical structure.

7. The Dewar shell structure for a cooled infrared detector according to claim 1, characterized in that, The inner wall of the Dewar shell has a striped, raised structure.

8. The Dewar shell structure for a cooled infrared detector according to claim 1, characterized in that, The striped protrusions on the Dewar shell and Dewar cold finger are used to increase their respective heat dissipation areas, which helps to control the temperature of the infrared detector.

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