CN107045251B - Space camera active refrigeration vacuum seal focal plane assembly - Google Patents

Abstract

The invention proposes an active cooling, vacuum-sealed space camera actively cooling and vacuum-sealing focal plane assembly, which can cool the detector to below -60°C, and effectively solves the problem of water vapor pollution when the traditional camera focal plane detector is refrigerated. The assembly includes focal plane box trimming gasket, pressure ring, vacuum glass window, vacuum focal plane box, vacuum sealing connector, refrigeration assembly, focal plane box base, focal plane box bottom plate, heat pipe, relay box, heat Sensitive resistor and thermoelectric refrigerator; vacuum glass window is sealed and pressed into the light hole by a pressure ring, and the front end of the pressure ring is provided with a focal plane trimming gasket; the refrigeration components include cold screen window, cold screen, active cooling CCD assembly and cold screen. Screen bottom plate; the cold screen window is installed in the cold screen gap; the back of the cold screen bottom plate is provided with a plurality of thermoelectric coolers and thermistors; the refrigeration components, the base of the focal plane box, the bottom plate of the focal plane box, and the heat pipe are all set on the vacuum focal plane In the cavity formed by the box body and the relay box body, a heat pipe is arranged on the back of the bottom plate of the focal plane box.

Description

A space camera active cooling vacuum-sealed focal plane assembly

technical field

The invention relates to the field of camera sealing devices, in particular to an active refrigeration vacuum sealing focal plane assembly of a space camera.

Background technique

Space astronomical cameras that observe dim targets have a long integration time and have high requirements for detector noise suppression. Generally, the method of cooling the detector is used to reduce the dark current of the detector and improve the signal-to-noise ratio of the camera. Thermo-Electric Cooling (TEC) technology is a refrigeration method using the Peltier effect. It does not require any working fluid, has no moving parts, and has a simple structure. It is very suitable for the refrigeration application of the focal plane of the aerospace camera. When the focal plane is tested on the ground, the temperature of the cooling focal plane is generally lower than the dew point of the environment, and the condensation of water vapor on the surface of the low-temperature detector will seriously affect the test results, and may even damage the aerospace detector.

In order to eliminate the phenomenon of condensation and frost, the focal surface box is generally stored in a nitrogen cabinet when the aerospace camera is tested on the ground, so that the focal surface is filled with nitrogen, and the desiccant is used to absorb water. However, for the astronomical camera that needs to be tested for a long time in this way, the water vapor will slowly enter the box, affecting the test effect, and the powder of the desiccant will contaminate the focal plane, which is not conducive to aerospace applications.

The traditional aerospace camera focal plane box is generally made of aluminum alloy material with good thermal conductivity. However, for the focal plane of the astronomical camera with a very low cooling temperature, the good thermal conductivity of the aluminum alloy will reduce the temperature of the sealed glass window to below the dew point temperature, causing the water vapor to condense on the glass window, which is not conducive to the test. The thermal expansion coefficient of the thermoelectric cooler does not match, which will cause the thermoelectric cooler to generate a large thermal stress and reduce the safety of the focal plane.

SUMMARY OF THE INVENTION

In order to solve the technical problem of water vapor condensation on the existing low-temperature focal surface, the present invention provides an active cooling and vacuum-sealed space camera active cooling vacuum-sealed focal surface assembly, which can cool the detector to below -60°C, effectively solving the traditional camera problem. The problem of water vapor contamination when the focal plane detector is cooled.

The technical solution provided by the present invention is:

An active cooling vacuum sealing focal plane assembly of a space camera, comprising a focal plane box trimming gasket 1, a pressure ring 2, a vacuum glass window 3, a vacuum focal plane box 4, a vacuum sealing connector 7, a refrigeration assembly, and a focal plane box The base 10, the focal plane box bottom plate 11, the heat pipe 12, the relay box 13, the thermistor and the thermoelectric refrigerator 14; the front end of the vacuum focal plane box 4 is provided with a light entrance hole, and the edge outside the light entrance hole is provided with The boss, the vacuum glass window 3 is sealed and pressed by the pressure ring 2 into the light hole, and the front end of the pressure ring 2 is provided with a focal plane trimming gasket 1; the side of the vacuum focal plane box 4 is provided with a plug-in hole; the vacuum focal plane The side of the box body 4 is provided with a vacuum pumping interface 15 and a vacuum gauge interface 16; the refrigeration assembly is arranged in the cavity of the focal plane box base 10; the refrigeration assembly includes a cold screen window 5, a cold screen 6, and an active cooling CCD assembly 8 and the cold screen bottom plate 9; the front end of the cold screen 6 is provided with a gap, and the cold screen window 5 is installed in the gap; the cold screen bottom plate 9 is provided with a window, and the active refrigeration CCD assembly 8 is arranged between the cold screen 6 and the cold screen bottom plate 9, The thermoelectric cooler 14 and the thermistor installed on the back of the active cooling CCD assembly 8 extend out of the cold screen bottom plate 9 through the window of the cold screen bottom plate 9, and the back of the cold screen bottom plate 9 is provided with a plurality of thermoelectric refrigerators 14 and thermistors. , the active refrigeration CCD assembly 8, the thermistor and the thermoelectric cooler 14 are connected to the vacuum sealing connector 7 through the plug-in hole on the side of the vacuum focal plane box 4; the refrigeration assembly, the focal plane box base 10, the focal plane box bottom plate 11, the heat pipe 12 are all arranged in the cavity formed by the vacuum focal plane box 4 and the relay box 13; The surface box base 10 and the focal surface box bottom plate 11 seal the rear end of the vacuum focal surface box 4; , The contact surface of the focal plane box base 10 and the focal plane box bottom plate 11 is provided with a sealing ring.

Further, the material of the vacuum focal plane box 4 is titanium alloy. The low thermal conductivity of titanium alloy can effectively increase the temperature of the vacuum glass window and prevent water vapor from condensing on the glass window.

Further, the section of the vacuum-sealed connector 7 is a racetrack-shaped circular section, and the section of the vacuum-sealed connector 7 is provided with a rubber pad 17 . Ensure the vacuum tightness of the electrical connection with the outside world.

Further, eight lugs are evenly arranged around the vacuum focal plane box 4, and eight screw through holes are arranged around the relay box 13, and the vacuum focal plane box 4 is respectively connected to the relay box through screws. 13 Fixed connection.

Further, the base plate 11 of the focal plane box adopts a molybdenum-copper alloy base plate with adjustable thermal expansion coefficient. The molybdenum-copper alloy material that matches the thermal expansion coefficient of the thermoelectric cooler (TEC) material is selected as the focal plane base plate, which solves the thermal stress problem of the TEC under the condition of large temperature difference and satisfies the high rigidity, high strength and high reliability of the focal plane box of the aerospace camera. requirements.

Further, four thermoelectric refrigerators 14 and four thermistors are arranged on the back of the cold screen base plate 9 ; the number of thermoelectric refrigerators 14 and thermistors installed on the back of the active cooling CCD assembly 8 is both two.

Further, a heat insulation pad is provided between the vacuum focal plane box 4 and the relay box 13 .

Further, the substrate of the active cooling CCD assembly 8 is made of aluminum nitride ceramics, and other surfaces other than the photosensitive surface are gold-plated to reduce radiation heat exchange.

Further, the inner and outer surfaces of the cold screen 6 and the cold screen bottom plate 9 are gold-plated, and the side of the focal plane box bottom plate 11 facing the active cooling CCD assembly 8 is gold-plated to reduce radiation heat exchange.

Further, thermal conductive silicone grease is coated between the contact surfaces of the heat pipe 12 and the bottom plate 11 of the focal plane box to reduce the contact thermal resistance.

The advantages of the present invention are:

1. The detector can be actively cooled to below -60°C, which effectively solves the problem of water vapor pollution when the traditional camera focal plane detector is cooled.

2. The molybdenum-copper alloy material that matches the thermal expansion coefficient of the thermoelectric cooler (TEC) material is selected as the focal plane base plate, which solves the thermal stress problem of the TEC under the condition of large temperature difference, and satisfies the high rigidity, high strength and high strength of the focal plane box of the aerospace camera. reliability requirements.

3. The focal plane assembly has structural features such as active refrigeration, vacuum sealing, light and miniaturization, and removable vacuum seals during launch.

4. The present invention uses a rubber sealing ring to seal the cavity where the CCD/CMOS of the focal plane of the camera is located, which solves the problem of contamination of the focal plane caused by water vapor entering the focal plane cavity.

5. The side wall of the focal plane box of the present invention has a vacuum pumping interface and a vacuum gauge interface, which can display the air pressure inside the focal plane box in real time.

6. The CCD assembly inside the focal plane box of the present invention has a cold screen outside the cover, and the cold screen is cooled by 4 small TECs to create a low temperature environment for the internal focal plane and minimize the influence of external space thermal radiation on the CCD temperature.

7. In the present invention, the connector adopts a track-shaped circular section rubber pad to contact with the side wall of the focal plane box, so as to ensure the vacuum tightness of the electrical connection part with the outside world.

8. The sub-buckle structure design between the parts in the present invention not only satisfies the overall sealing of the focal plane box, but also prevents the electromagnetic leakage and other problems of the focal plane box.

9. The bottom plate of the focal plane box in the present invention is made of molybdenum-copper alloy material, which is consistent with the thermal expansion coefficient of the material of the thermoelectric refrigerator in the CCD assembly, ensuring the safety of the thermoelectric refrigerator in the process of large-scale temperature changes.

Description of drawings

Figure 1 is a sectional view of the overall structure of the camera vacuum focal plane box;

Figure 2 is an exploded view of the camera vacuum focal plane box;

Fig. 3 is a schematic diagram of the shell structure of the vacuum focal plane box;

Figure 4 is a schematic structural diagram of a CCD assembly and a gold-plated cold screen;

FIG. 5 is a schematic structural diagram of a vacuum-sealed connector.

The reference signs are: 1- focal plane box trimming gasket, 2- press ring, 3- vacuum glass window, 4- vacuum focal plane box, 5- cold screen window, 6- cold screen, 7- vacuum seal Connector, 8-active cooling CCD assembly, 9-cold screen bottom plate, 10-focal plane box base, 11-focal plane box bottom plate, 12-heat pipe, 13-relay box, 14-thermoelectric cooler (TEC), 15-vacuum pumping interface, 16-vacuum gauge interface, 17-rubber pad.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, the content of the present invention is described in further detail:

As shown in Figure 1, Figure 2, Figure 3, the space camera's active cooling vacuum sealing focal plane assembly includes a focal plane box trimming gasket 1, a pressure ring 2, a vacuum glass window 3, a vacuum focal plane box 4, a vacuum sealing joint Plug-in 7, refrigeration assembly, focal plane box base 10, focal plane box bottom plate 11, heat pipe 12, relay box 13, thermistor and thermoelectric cooler 14; the front end of the vacuum focal plane box 4 is provided with a light entrance hole, The edge outside the light entrance hole is provided with a boss, the vacuum glass window 3 is sealed and pressed on the box outside the light entrance hole by a pressure ring 2, and the front end of the pressure ring 2 is provided with a focal plane box trimming gasket 1; The side of the focal plane box 4 is provided with a plug-in hole; the side of the vacuum focal plane box 4 is provided with a vacuum suction interface 15 and a vacuum gauge interface 16; the refrigeration component is arranged in the cavity of the focal plane box base 10; the refrigeration component It includes a cold screen window 5, a cold screen 6, an active cooling CCD assembly 8 and a cold screen bottom plate 9; the front end of the cold screen 6 is provided with a gap, the cold screen window 5 is installed in the gap, and the active cooling CCD assembly 8 is arranged on the cold screen 6 and the cold screen. Between the cold screen bottom plates 9; the cold screen bottom plate 9 is provided with a window, the thermoelectric cooler 14 and the thermistor installed on the back of the active cooling CCD assembly 8 pass through the cold screen bottom plate 9 window and extend out of the cold screen bottom plate 9, and the cold screen bottom plate 9 A plurality of thermoelectric coolers 14 and thermistors are arranged on the back of the camera. The active cooling CCD assembly 8 , thermistors and the thermoelectric coolers 14 are connected to two vacuum-sealed connectors 7 through the plug-in holes on the side of the vacuum focal plane box 4 .

The refrigeration assembly, the focal plane box base 10 , the focal plane box bottom plate 11 and the heat pipe 12 are all arranged in the cavity formed by the vacuum focal plane box body 4 and the relay box body 13 ; At the rear, a heat pipe 12 is provided on the back of the focal plane box bottom plate 11 , and the rear end of the vacuum focal plane box body 4 is sealed by the focal plane box base 10 and the focal plane box bottom plate 11 . The contact surfaces of the vacuum focal plane box 4 and the vacuum glass window 3, the contact surfaces of the vacuum focal plane box 4 and the focal plane box base 10, and the contact surfaces of the focal plane box base 10 and the focal plane box bottom plate 11 are all provided with seals. lock up.

The front end of the vacuum focal plane box 4 is flanged to the rear optical system of the camera. It adopts a flanging design to prevent stray light from entering the focal plane. The vacuum glass window 3 is used to seal the light entrance hole at the front end of the vacuum focal plane box 4. 10 and the bottom plate 11 of the molybdenum-copper alloy focal plane box to seal the rear end of the vacuum focal plane box 4, the active cooling CCD assembly 8 is installed on the bottom plate 11 of the molybdenum-copper alloy focal plane box, and the heat pipe 12 is installed on the back to transport the heat of the CCD assembly out. The vacuum focal plane box 4 and the relay box 13 are connected by screws and heat insulation pads, and the relay box 13 is connected with the rear-end focal plane electronic components. The CCD assembly is cooled by two secondary TECs, and the CCD assembly is covered by a low temperature cold screen 6.

The focal plane box trimming gasket 1 is located between the front end of the vacuum focal plane box 4 and the rear optical system. The focal plane box trimming gasket 1 is made of thermal insulation material, which can focus on the verticality of the plane box to the optical axis and the focal plane. The box trims the distance of the rear optical system, and can insulate the heat transfer from the front panel to the vacuum focal plane box.

The thickness of the vacuum glass window 3 is analyzed and calculated. The thickness of the vacuum glass window 3 is 8 mm and the diameter is 40 mm, which can not only ensure the correct position of the optical focal plane, but also ensure the surface shape under atmospheric pressure. The pressure ring 2 is installed on the front end of the vacuum focal plane box 4 . Use a rubber gasket to obtain a sealing effect.

The substrate of the active cooling CCD component 8 is aluminum nitride ceramics. Except for the photosensitive surface, other surfaces of the CCD component are gold-plated. Two thermistors are pasted on the upper surface of the CCD component substrate near the readout area to monitor and control the temperature of the CCD. The CCD flexible cable is connected to the vacuum-sealed connector 7, and two TECs are used to actively cool the back of the CCD substrate to ensure the temperature during the operation of the CCD.

As shown in Figure 4, the gold-plated cold screen 6 and the gold-plated cold screen bottom plate 9 are made of aluminum alloy with high thermal conductivity. Plug-in design, the left and right halves are inserted into the active cooling CCD assembly 8 from the left and right sides, avoiding the TEC. The cold shield bottom plate 9 is connected to the cold shield 6 through screws, and 4 TECs are used to cool the CCD to build a low temperature radiation environment. The cold shield 6 surface is pasted with a thermistor at each of the 4 TEC positions. The cold screen window 5 corresponds to the photosensitive surface of the CCD, and is a rectangular parallelepiped window.

The side of the molybdenum copper alloy base plate 11 facing the CCD is gold-plated, and the inner surface is the hot end mounting surface of the 6 TECs. The TECs are pasted on the inner surface of the TEC substrate through GD-414C black silicone rubber, and are connected to the focal plane box base 10 through 12 screws. Connections are vacuum sealed with rubber gaskets. The outer surface of the focal plane box bottom plate 11 is the installation surface of the evaporation end of the heat pipe 12. The two heat pipes are connected to the back of the focal plane box bottom plate 11 through 12 mounting holes. The contact surfaces are coated with thermal grease to reduce the contact thermal resistance.

The vacuum focal plane box 4 is made by integral molding of titanium alloy, and is installed and fixed with the rear optical system by titanium alloy screws, and is connected by 12 screws. Two sealing connectors are installed on two sides of the focal plane box, which are respectively connected to the CCD and TEC by flexible cables, and the other two sides are the vacuum pumping interface 15 and the vacuum gauge interface 16 respectively.

As shown in FIG. 5 , the surface of the vacuum sealing connector 7 is machined with annular grooves, embedded with a racetrack-shaped circular section rubber gasket 17, and installed with the vacuum focal plane box 4 to obtain a vacuum sealing effect.

Claims (9)

1. An active refrigeration vacuum-sealed focal plane assembly for a space camera, characterized in that it comprises a focal plane box trimming gasket (1), a pressure ring (2), a vacuum glass window (3), a vacuum focal plane box (4) ), vacuum-sealed connectors (7), refrigeration components, focal plane box base (10), focal plane box bottom plate (11), heat pipes (12), relay boxes (13), thermistors and thermoelectric coolers ( 14); The front end of the vacuum focal plane box (4) is provided with a light entrance hole, and the edge outside the light entrance hole is provided with a boss, and the vacuum glass window (3) is sealed by a pressure ring (2) into the light entrance hole, and the pressure ring (2) The front end of the vacuum focal plane box is provided with a trimming gasket (1); the side of the vacuum focal plane box (4) is provided with a plug-in hole; the side of the vacuum focal plane box (4) is provided with a vacuum suction interface (15) and Vacuum gauge interface (16); The refrigeration assembly is arranged in the cavity of the focal plane box base (10); the refrigeration assembly includes a cold screen window (5), a cold screen (6), an active cooling CCD assembly (8) and a cold screen bottom plate (9); the cold screen ( 6) The front end is provided with a gap, and the cold screen window (5) is installed in the gap; the cold screen bottom plate (9) is provided with a window, and the active cooling CCD assembly (8) is arranged on the cold screen (6) and the cold screen bottom plate (9) In between, the thermoelectric cooler (14) and the thermistor installed on the back of the active cooling CCD assembly (8) protrude out of the cold screen bottom plate (9) through the window of the cold screen bottom plate (9), and the The back is provided with a plurality of thermoelectric coolers (14) and thermistors, and the active cooling CCD assembly (8), thermistors and the thermoelectric coolers (14) are sealed with the vacuum through the plug-in holes on the side of the vacuum focal plane box (4). The connector (7) is connected; The refrigeration assembly, the focal plane box base (10), the focal plane box bottom plate (11), and the heat pipe (12) are all arranged in the cavity formed by the vacuum focal plane box body (4) and the relay box body (13); the focal plane box body (13); The bottom plate (11) is arranged behind the focal plane box base (10), the back of the focal plane box bottom plate (11) is provided with a heat pipe (12), and the focal plane box base (10) and the focal plane box bottom plate (11) are used to seal the vacuum The rear end of the focal plane box (4); The contact surface of the vacuum focal plane box (4) and the vacuum glass window (3), the contact surface of the vacuum focal plane box (4) and the focal plane box base (10), the focal plane box base (10) and the focal plane box Sealing rings are provided on the contact surfaces of the bottom plate (11) to prevent water vapor from entering the focal plane cavity and causing contamination on the focal plane; The material of the vacuum focal plane box (4) is titanium alloy. 2. The space camera active refrigeration vacuum sealing focal plane assembly according to claim 1, characterized in that: the section of the vacuum sealing connector (7) is a racetrack-shaped circular section, and the section of the vacuum sealing connector (7) is provided with a rubber pad ( 17). 3. The space camera active refrigeration vacuum sealing focal plane assembly according to claim 1 or 2, characterized in that: the vacuum focal plane box (4) is evenly provided with eight lugs around it, and the relay box (13) Eight screw through holes are arranged around the focal plane, and the vacuum focal plane box (4) is fixedly connected to the relay box (13) through screws. 4 . The active refrigeration vacuum-sealed focal plane assembly of a space camera according to claim 3 , wherein the bottom plate ( 11 ) of the focal plane box adopts a molybdenum-copper alloy bottom plate with adjustable thermal expansion coefficient. 5 . 5. The space camera active refrigeration vacuum-sealed focal plane assembly according to claim 4, characterized in that: four thermoelectric refrigerators (14) and four thermistors are arranged on the back of the cold screen bottom plate (9); active refrigeration The number of thermoelectric coolers (14) and thermistors mounted on the back of the CCD assembly (8) is two. 6 . The active refrigeration vacuum-sealed focal plane assembly of a space camera according to claim 5 , wherein a heat insulation pad is arranged between the vacuum focal plane box ( 4 ) and the relay box ( 13 ). 7 . 7 . The active cooling vacuum sealing focal plane assembly of the space camera according to claim 6 , wherein the substrate of the active cooling CCD assembly ( 8 ) is aluminum nitride ceramics, and other surfaces other than the photosensitive surface are plated with gold. 8 . 8. The space camera active refrigeration vacuum-sealed focal plane assembly according to claim 7, wherein the inner and outer surfaces of the cold screen (6) and the cold screen bottom plate (9) are gold-plated, and the focal plane box bottom plate (11) The side facing the active cooling CCD assembly (8) is gold-plated. 9 . The active refrigeration vacuum-sealed focal plane assembly of a space camera according to claim 8 , characterized in that thermal conductive silicone grease is applied between the contact surfaces of the heat pipe ( 12 ) and the bottom plate ( 11 ) of the focal plane box. 10 .

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