Multi-purpose cryogenic optical adaptive infrared detector dewar structure

Abstract

The application discloses a multi-purpose cold optical self-adaptive infrared detector Dewar structure, which comprises a lens, a cold shield, a cold pupil, a slit, a chip, a ceramic electrode plate, a lead ring, a shell, a core column, a cold platform, a gem cold chain and the like. The high-precision packaging requirement of the Dewar cold optical element is realized through the high-precision centering installation between the lens, the cold shield, the cold pupil, the slit, the ceramic electrode plate and the detector chip, and the detachable installation structure of the gem cold chain and the cold platform enables the Dewar assembly to meet the testing conditions of the detector normal temperature environment or the packaging process and to be applicable to the working state in the full low-temperature cold box. The application can effectively ensure the high-precision requirement of the low-temperature infrared optics and is suitable for the packaging structure of the detector Dewar assembly for cold optics of various purposes.

Description

Technical Field

[0001] This invention relates to an integrated cold optics infrared detector Dewar packaging technology, specifically a multi-purpose cold optics adaptive infrared detector Dewar structure. Background Technology

[0002] With the development of space infrared detection technology, the demand for high-resolution and high-sensitivity detection systems is becoming increasingly urgent. When the performance of infrared devices reaches the background detection limit, the background radiation mainly comes from the instrument's optical system and its supporting structure. The adverse effects are mainly twofold: First, stray radiation generated by the optical and mechanical components of the optical system reduces the system's signal-to-noise ratio and contrast, especially in the space environment where the target signal is very weak. Second, for wide-field-of-view, high-sensitivity infrared optical systems, due to the large field of view and small F-number, it is necessary to encapsulate some cold optical lenses near the detector; otherwise, the entire optomechanical system would be very large and complex. To further improve the detection capability of infrared systems, using cryogenic cooling technology to cool the infrared optical components, reducing the background photon flux and lowering its background thermal noise, is one of the most effective measures to improve detection sensitivity. This has led to the development of cold-optically integrated detector cold box or Dewar packaging structures. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-purpose cold optical adaptive infrared detector Dewar structure to solve the need for infrared detector Dewar components to meet both the testing conditions of the detector in ambient temperature environment or packaging process, and to be suitable for working in a fully cryogenic cold box.

[0004] A multi-purpose cold optical adaptive infrared detector Dewar structure of the present invention is shown in the appendix. Figure 1As shown, it includes a lens 1, a cold screen 2, a cold pupil 3, a slit 4, a chip 5, a ceramic electrode plate 6, a lead ring 7, a housing 8, a core post 9, a lead wire protective cover 10, a cold platform 11, and a gemstone cold chain 12. Lens 1, cold pupil 3 and slit 4 are aligned and glued together on cold screen 2. Each alignment and glued connection is centered on the optical axis to control the alignment deviation within a small range. Cold platform 11 and jewel cold chain 12 are connected by threads. 1-2 pieces of 0.1mm thick indium sheet are added between the coupling contact surfaces of cold platform 11 and jewel cold chain 12. Lead wire protection cover 10 is assembled on lead wire ring 7 and fastened with screws. The Dewar structure when installing jewel cold chain 12 and lead wire protection cover 10 is suitable for Dewar working state in full low temperature cold box. When testing Dewar in normal temperature environment or during the packaging process, only jewel cold chain 12 and lead wire protection cover 10 need to be removed. A window cap assembly 13 (window cap 1302 with optical window 1301 and evacuation copper pipe 1303) is installed at the mating flange position of lead wire protection cover 10. A rubber ring (14) is installed between lead wire ring 7 and window cap 1303 for sealing.

[0005] The cold pupil (3) is made of Kovar material. There is a circular hole with a specific optical angle chamfer at the center of the cold pupil (3). The overall structure is a thin sheet with a small diameter and the surface is plated with black nickel. The slits (4) are all made of Kovar material. There is a rectangular inverted cone hole with a specific optical taper requirement at the center. The overall structure is a thin sheet with a small diameter and the surface is plated with black nickel. The cold screen (2) is integrally formed using Kovar material. The outer surface is polished and then plated with gold. The inner surface retains the bonding area of ​​the lens (1), cold pupil (3) and slit (4) and the other areas are treated with blackened graphene. The upper part of the lead wire protection cover (10) is a thin-walled structure. The lower part has four symmetrically and evenly distributed threaded holes. The lead wire protection cover (10) is made of Kovar material. Both the inner and outer surfaces are polished and then plated with gold.

[0006] The implementation method of this invention is as follows:

[0007] 1) After the parts are processed, the required surface treatments are carried out on the parts, including cleaning, polishing, gold plating, blackening, etc.

[0008] 2) The cold platform 11, core column 9, outer shell 8 and lead ring 7 are connected in an airtight manner by laser welding using a special welding fixture. The flanges of lead ring 7 and core column 9 are aligned with the structural direction requirements using a profilometer with an alignment rotation angle of less than 1°.

[0009] 3) Under high magnification profilometer, the electrode plate 6 and the cold platform 11 are aligned and bonded. Then the chip 5 is aligned and bonded to the electrode plate 6. After the adhesive is cured, the chip 5 and the electrode plate 6 are interconnected with the electrode plate 6 and the lead ring 7 by gold wire ball bonding.

[0010] 4) Under the high magnification profilometer, slit 4 is aligned and bonded to cold screen 2, cold screen 2 to electrode plate 6, cold screen 2 to cold pupil 3, and cold screen 2 to lens 1 in sequence. Each alignment and bonding is controlled with the optical axis as the center to keep the alignment deviation within a small range.

[0011] 5) Support and clamp the cold cap 1201, gem rod 1202, and flexible cold chain transition block 1203 with a special brazing fixture, and integrate the gem cold chain 12 by vacuum brazing; the cold cap 1201 on the gem cold chain 12 needs to be machined to match the thread of the cold platform 11; and the flexible cold chain transition block 1203 needs to be finely repaired according to the structural requirements of the Dewar in the cold box.

[0012] 6) Install the sapphire cold chain 12 with the cold platform 11. Add 1-2 indium sheets with a thickness of 0.1mm between the coupling contact surfaces of the cold platform 11 and the sapphire cold chain 12 to improve thermal coupling efficiency and avoid rigid contact between the sapphire cold chain 12 and the cold platform 11, which would increase the additional stress on the chip.

[0013] 7) Install the lead wire protection cover 10 with the lead wire ring 7 and fix the lead wire protection cover 10 with four evenly distributed screws.

[0014] 8) If testing is to be performed in a normal temperature environment or during the packaging process, remove the lead protection cover 10 and the jewel cold chain 12, and then install a window cap assembly 13 (window cap 1302 with optical window 1301 and evacuation copper tube 1303) at the mating flange position where the lead protection cover 10 is installed. Clamp it with a special fixture and insert a rubber ring 14 between the lead ring 7 and the window cap 1302 for sealing.

[0015] The above describes the implementation process of a multi-purpose cold optical adaptive infrared detector Dewar structure according to the present invention.

[0016] The advantages of this invention are:

[0017] 1) The present invention has a simple structure and is easy to operate;

[0018] 2) The gemstone cold chain used in this invention has good thermal conductivity, which can effectively reduce the thermal resistance between the refrigerator and the chip and improve the heat transfer efficiency between the refrigerator and the chip.

[0019] 3) It solves the need for the infrared detector Dewar assembly to meet both the testing conditions of the detector at room temperature or during the packaging process, and to be used in a fully cryogenic cold box. Attached Figure Description

[0020] Figure 1 This is a Dewar structure for a multi-purpose cold optics adaptive infrared detector;

[0021] In the diagram: 1 - Lens;

[0022] 2-Cold screen;

[0023] 3-Cold eyes;

[0024] 4-Slit;

[0025] 5-chip;

[0026] 6-Ceramic electrode plate;

[0027] 7-Lead ring;

[0028] 8-Outer shell;

[0029] 9-Core column;

[0030] 10 - Lead wire protection cover;

[0031] 11-Cold platform;

[0032] 12-Gemstone Cold Chain;

[0033] 1201 - Beanie;

[0034] 1202-Gem Rod;

[0035] 1203 - Flexible cold chain transition block.

[0036] Figure 2 Cross-sectional view of the window cap assembly and rubber band installation.

[0037] Figure 3 This is a schematic diagram of a ceramic electrode plate.

[0038] Figure 4 This is a cross-sectional view of the cold pupil structure.

[0039] Figure 5 This is a cross-sectional view of the slit structure. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples:

[0041] This example demonstrates a 128×2 long-wave infrared detector Dewar assembly used in a project. (See attached image.) Figure 1 As shown, its main implementation method is as follows:

[0042] 1) After the parts are machined, the outer surface of the cold screen, the inner surface of the lead ring protective cover, the inner surface of the core column, the inner surface of the outer shell, and the inner surface of the lead ring are mirror polished. After polishing, the residual polishing paste is cleaned. Then, the parts are cleaned in an ultrasonic cleaner for 5-10 minutes with acetone, alcohol, and deionized water in sequence to remove the grease and debris remaining on the surface of the parts during processing. The outer surface of the polished and cleaned cold screen is gold-plated with a gold plating thickness of 2.5μm. The inner surface is left with an adhesive bonding area, and the other parts are blackened with graphene with a blackening thickness of 0.25mm. The inner and outer surfaces of the lead ring protective cover are gold-plated with a gold plating thickness of 2.5μm.

[0043] 2) Using a dedicated welding fixture, the cold platform 11, core post 9, outer shell 8, and lead ring 7 are connected in an airtight manner by laser welding, with a laser welding leakage rate better than 1.0×10⁻⁶. -10 torr.l / s, and according to the structural orientation requirements, use a profilometer to align the flanges of lead ring 7 and core post 9, with an alignment rotation angle of 0.06°.

[0044] 3) Under high magnification profilometer, the electrode plate 6 and the cold platform 11 are aligned and bonded. Then the chip 5 is aligned and bonded to the electrode plate 6. After the adhesive is cured, the chip 5 and the electrode plate 6 are interconnected with the electrode plate 6 and the lead ring 7 by gold wire ball bonding.

[0045] 4) Under the high magnification profilometer, slit 4 is aligned and bonded to cold screen 2, cold screen 2 to electrode plate 6, cold screen 2 to cold pupil 3, and cold screen 2 to lens 1 in sequence. Each alignment and bonding is controlled with the optical axis as the center and the alignment deviation is better than 0.008mm.

[0046] 5) Support and clamp the cold cap 1201, sapphire rod 1202, and elastic cold chain transition block 1203 using a special brazing fixture. After the special brazing fixture (300) is used for support and clamping, place it in a high-temperature furnace. When the vacuum degree is better than 5×10 -3 Pa can start brazing heating, set the temperature control program for brazing, set the brazing flow point temperature to 810±5℃, and integrate the gem cold chain 12 by vacuum brazing; the cold cap 1201 on the gem cold chain 12 needs to be machined to match the thread of the cold platform 11; and the elastic cold chain transition block 1203 is finely processed according to the needs of Dewar in the cold box.

[0047] 6) Install the sapphire cold chain 12 with the cold platform 11. Add two 0.1mm thick indium sheets between the coupling contact surfaces of the cold platform 11 and the sapphire cold chain 12 to improve thermal coupling efficiency. At the same time, avoid rigid contact between the sapphire cold chain 12 and the cold platform 11 to avoid increasing additional stress on the chip. Apply appropriate torque to ensure that the direction of the finely repaired elastic cold chain transition block 1203 is consistent with the direction of the core flange.

[0048] 7) Install the lead wire protection cover 10 with the lead wire ring 7, and then use 4 M1.6 screws to apply torque from the screw holes on the side of the lead wire protection cover 10 to fix the lead wire protection cover 10; it can be directly installed and integrated into the cold box for use in the whole machine for cryogenic cold optics.

[0049] 8) If testing is to be performed in a normal temperature environment or during the packaging process, the lead wire protection cover 10 and the sapphire cold chain 12 need to be removed. Then, a window cap assembly 13 (a window cap 1302 with an optical window 1301 and a vacuum copper tube 1303) should be installed at the mating flange position where the lead wire protection cover 10 is installed. The assembly should be clamped with a special fixture. A rubber ring 14 should be installed between the lead wire ring 7 and the window cap 1302 for sealing. A vacuum should be drawn through the vacuum copper tube 1303. Liquid nitrogen should be poured into the back position of the core post 9 to perform low-temperature performance testing of the detector.

[0050] The above describes the implementation process of a multi-purpose cold optical adaptive infrared detector Dewar structure according to the present invention.

Claims

1. A multi-purpose cold optical adaptive infrared detector Dewar structure, comprising a lens (1), a cold screen (2), a cold pupil (3), a slit (4), a chip (5), a ceramic electrode plate (6), a lead ring (7), a housing (8), a core post (9), a lead protection cover (10), a cold platform (11), and a sapphire cold chain (12), characterized in that: The lens (1), cold pupil (3), and slit (4) are aligned and bonded together on the cold screen (2); the cold platform (11) and the jewel cold chain (12) are connected by threads; the lead wire protection cover (10) is mounted on the lead wire ring (7) and fastened with screws; the jewel cold chain (12) is installed in conjunction with the cold platform (11), and 1-2 indium sheets with a thickness of 0.1mm are added between the coupling contact surfaces of the cold platform (11) and the jewel cold chain (12); the jewel cold chain (12) and the lead wire protection cover (10) are then installed. The Dewar structure is suitable for Dewar operation in a fully cryogenic cold box; during the Dewar encapsulation process test, only the jewel cold chain (12) and lead wire protection cover (10) need to be removed, and a window cap assembly (13) is installed at the mating flange position of the lead wire protection cover (10). The window cap assembly (13) is a window cap (1302) with an optical window (1301) and a vacuum copper tube (1303); a rubber ring (14) is installed between the lead wire ring (7) and the window cap (1302) for sealing.

2. The Dewar structure for a multi-purpose cold optics adaptive infrared detector according to claim 1, characterized in that: The cold pupil (3) is made of Kovar material. The cold pupil (3) has a circular hole with a specific optical angle bevel at its center. It adopts a thin sheet structure and is plated with black nickel.

3. The Dewar structure for a multi-purpose cold optics adaptive infrared detector according to claim 1, characterized in that: The slit (4) is made of Kovar material, with a rectangular inverted cone hole at the center that meets specific optical taper requirements. It has a thin sheet structure and is plated with black nickel.

4. The Dewar structure for a multi-purpose cold optics adaptive infrared detector according to claim 1, characterized in that: The cold screen (2) is integrally formed using Kovar material. After polishing the outer surface, it is gold-plated. The inner surface retains the bonding area of ​​the lens (1), cold pupil (3) and slit (4), while the other areas are blackened with graphene.

5. The Dewar structure for a multi-purpose cold optics adaptive infrared detector according to claim 1, characterized in that: The upper part of the lead wire protection cover (10) has a thin-walled structure, and the lower part has four symmetrically and evenly distributed threaded holes. The lead wire protection cover (10) is made of Kovar, and both the inner and outer surfaces are polished and then gold-plated.

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