Relay low-temperature infrared detection system

Abstract

The utility model relates to an infrared detection system, in particular to a relay low-temperature infrared detection system, which is used for solving the problems that an optical element in a traditional infrared detection system can generate larger thermal noise due to self thermal radiation, so that a signal of a low-energy target is submerged, the detection sensitivity is reduced, and the detection cost is reduced. And a traditional relay optical system and a telescope optical system are difficult to realize perfect matching, and long-distance target imaging and observation effects are influenced. The relay low-temperature infrared detection system mainly comprises a flange plate, a shell and at least one low-temperature cold source group, wherein a vacuum cavity is formed in the shell; a relay infrared optical lens which comprises a lens frame and is composed of a plurality of free-form surface off-axis reflectors and is sequentially arranged on the lens frame along a light path is arranged in the vacuum cavity; through a low-temperature working environment, a material consistency design, an off-axis optical design, flexible sealing adjustment, uniform temperature field control and a vacuum environment, the detection sensitivity of the system and the imaging capability of a long-distance target are remarkably improved.

Description

Technical Field

[0001] The utility model relates to an infrared detection system, in particular to a relay cryogenic infrared detection system. Background Art

[0002] Infrared detection technology realizes the detection, identification and tracking of targets by detecting the infrared energy radiated by objects, and has been widely used in fields such as astronomical observation, optical remote sensing, and navigation. However, with the increasing demand for detecting weak targets at long distances, the detection sensitivity of traditional infrared detection systems is greatly affected by the thermal noise generated by optical elements.

[0003] Traditional infrared detection systems usually adopt optical elements such as optical lenses and mirrors. During the working process, these elements generate a large amount of thermal noise due to their own thermal radiation, which in turn masks the low-energy target signals and reduces the sensitivity of the detection system. This is one of the main technical bottlenecks faced by traditional infrared detection technology.

[0004] In addition, relay optical systems are widely used in long-distance imaging and detection scenarios, such as astronomical observation and other fields. By being connected in series with a front telescopic system, relay optical systems can achieve functions such as image steering, focal length scaling, and field of view segmentation. However, when designing a relay optical system, how to ensure its perfect matching with the front telescopic system to improve the system performance is another technical problem. Summary of the Utility Model

[0005] !The purpose of the utility model is to solve the deficiencies that the optical elements in traditional infrared detection systems generate relatively large thermal noise due to their own thermal radiation, resulting in the signal of low-energy targets being submerged, thereby reducing the detection sensitivity, and that it is difficult for traditional relay optical systems to achieve perfect matching with telescopic optical systems, affecting the imaging and observation effects of long-distance targets, and to provide a relay cryogenic infrared detection system.

[0006] In order to solve the above-mentioned deficiencies of the prior art, the utility model provides the following technical solutions:

[0007] A relay cryogenic infrared detection system, which is characterized in that it includes a flange, a housing, and at least one cryogenic cold source group;

[0008] One end of the flange is connected to the housing, and the other end is provided with an image plane trimming gasket for connecting to a front telescopic system;

[0009] The interior of the housing is a vacuum chamber, and an optical light inlet hole and an optical light outlet are provided on the side wall for connecting the vacuum chamber; a relay infrared optical lens is arranged in the vacuum chamber, and the relay infrared optical lens includes a lens frame and a plurality of reflectors sequentially arranged on the lens frame along the optical path. The plurality of reflectors are all free-form off-axis reflectors and are made of the same material as the lens frame; an optical window and an infrared focal plane assembly are respectively arranged in the optical light inlet hole and the optical light outlet, and a set of flexible sealing components is arranged between the optical light outlet and the infrared focal plane assembly; the outgoing light of the front telescopic system sequentially passes through the inner hole of the flange, the optical window, and the plurality of reflectors and then reaches the infrared focal plane assembly;

[0010] At least one temperature sensor is arranged on each reflector, and the outer surface of the lens frame is coated with a first graphite film, and a heat insulation component is arranged between the first graphite film and the inner wall of the vacuum chamber; at least three heat insulation support seats are arranged between the bottom surface of the lens frame and the inner wall of the vacuum chamber;

[0011] The cryogenic cold source group includes two cryogenic cold sources located outside the housing, and the output end of each cryogenic cold source is connected to the lens frame through a flexible cold chain; the flexible cold chain passes through the housing, and a set of flexible sealing components is arranged between the flexible cold chain and the housing.

[0012] Further, the plurality of reflectors are specifically four, and the four reflectors and the lens frame are all made of aluminum alloy.

[0013] Further, a support cold plate is arranged on the bottom surface of the lens frame, the first graphite film is wrapped on the support cold plate, and the support cold plate is connected to the flexible cold chain.

[0014] Further, the flexible cold chain includes a heat conduction lock and a second graphite film connected in parallel.

[0015] Further, the heat insulation component includes two sets of heat insulation materials respectively arranged on the first graphite film and the inner wall of the vacuum chamber, and double-sided aluminized polyester films respectively arranged on the outer surfaces of the two sets of heat insulation materials.

[0016] Further, each set of flexible sealing components includes a flexible bellows and a sealing ring; one ends of the two flexible bellows are both connected to the housing, and a sealing ring is arranged between the flexible bellows and the housing, and the other ends are respectively connected to the infrared focal plane assembly and the flexible cold chain.

[0017] Further, each heat insulation support seat includes a metal support seat. The metal support seat is a cylinder, and a plurality of through holes are arranged on the side wall. A first cushion column is coaxially arranged at the upper end of the metal support seat, and two second cushion columns are symmetrically arranged at the lower end. The metal support seat is made of titanium alloy, and the first cushion column and the two second cushion columns are both made of glass fiber reinforced plastic.

[0018] Further, an optical window is disposed in the optical light inlet hole through a vacuum sealant; the infrared focal plane assembly includes a detector window, a detector cold stop, and a detector focal plane that are sequentially arranged along the optical path; the optical light outlet is disposed at one end of the infrared focal plane assembly close to the detector window.

[0019] Further, a vacuum valve and a vacuum gauge tube communicating with the vacuum chamber are disposed on the side wall of the housing; the vacuum valve is connected to a molecular pump set through a KF flange for evacuating the vacuum chamber; the vacuum gauge tube is used for real-time detection of the vacuum degree of the vacuum chamber.

[0020] Further, an electrical connector is disposed on the housing, and the input ends of the electrical connector are respectively connected to all the temperature sensors, and the output end is used for connecting an external upper computer.

[0021] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0022] (1) A relay cryogenic infrared detection system of the present utility model effectively solves the problems of thermal noise of a traditional infrared detection system and the matching between a relay optical system and a telescopic optical system through a cryogenic working environment, material consistency design, off-axis optical design, flexible seal adjustment, uniform temperature field control, and vacuum environment, and significantly improves the detection sensitivity of the system and the imaging ability of a long-distance target.

[0023] (2) The present utility model can be connected in series with a front telescopic system, so as to scale the focal length and realize the detection of a long-distance point target; and because the relay infrared optical lens adopts the same material, an athermalization design of the relay infrared optical lens can be realized, making it applicable to a wide dynamic working environment temperature of 80K to 350K, and not affecting the imaging quality or detection performance due to changes in air pressure and temperature; and fine adjustment between the relay infrared optical lens and the infrared focal plane assembly is realized through a flexible seal assembly, improving the imaging and detection accuracy.

[0024] (3) The present utility model significantly reduces the thermal gradient of optical elements through uniform temperature field control, ensures the detection performance of the optical system, and thus improves the detection ability of long-distance weak targets, specifically including:

[0025] In the present utility model, the relay infrared optical lens adopts a free-form surface off-axis four-reflection structure form. Under the same optical system indexes, the number of optical elements is small, the volume is compact, the heat capacity of the whole system is reduced, and therefore, the required refrigeration capacity of the system is small, and the system cooling time can be greatly shortened;

[0026] In the present utility model, the flexible cold chain between the cryogenic cold source heat conductor of the middle and low temperatures and the relay infrared optical lens adopts a heat conduction structure form combining a heat conduction lock and a graphite film, reducing the thermal resistance of the heat conduction link, enhancing the heat conduction ability between the cold head of the refrigerator and the relay infrared optical lens, greatly increasing the cooling rate of the relay infrared optical lens, that is, shortening the system cooling time;

[0027] In the present utility model, heat insulation materials are arranged on the inner side of the shell and the outer side of the relay infrared optical lens, and a double-sided aluminized polyester film is arranged on the outer surface of the heat insulation material, preventing radiative heat exchange between the two components, thereby greatly shortening the system cooling time;

[0028] The outer surface of the relay infrared optical lens in the present utility model is coated with a first graphite film, making the temperature fields of the four reflectors more uniform, thereby avoiding the change of the reflector surface shape caused by the temperature gradient of a single reflector and also avoiding the change of the optical interval and surface shape of the optical system caused by the temperature gradient of the four reflectors, ultimately affecting the imaging quality or detection performance of the optical system.

[0029] (4) The present utility model is docked with the flange of the front telescopic system through a flange, and by trimming the image plane trimming gasket between the flanges, the relay optical system is made to match the telescopic optical system 100%. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the optical path docking between an embodiment of a relay cryogenic infrared detection system of the present utility model and a front telescopic system;

[0031] Figure 2 It is a cross-sectional view of an embodiment of the present utility model;

[0032] Figure 3 It is an axonometric drawing of an embodiment of the present utility model;

[0033] Figure 4 It is a cross-sectional view of a relay infrared optical lens and an infrared focal plane assembly in an embodiment of the present utility model;

[0034] Figure 5 It is a schematic diagram of the structure of the flexible cold chain, support cold plate and temperature sensor of the relay infrared optical lens in an embodiment of the present utility model;

[0035] Figure 6 It is a schematic diagram of the structure of the heat insulation support seat in an embodiment of the present utility model;

[0036] Figure 7 It is a schematic diagram of the structure of the flexible seal assembly in an embodiment of the present utility model;

[0037] Figure 8 It is an image of star B310 obtained after the embodiment of the present utility model is docked with the front telescopic system.

[0038] The description of the reference numerals is as follows:

[0039] 1 - Relay infrared optical lens, 101 - First mirror, 102 - Second mirror, 103 - Third mirror, 104 - Fourth mirror, 105 - Frame, 106 - Cover plate, 107 - Durable focal plane; 2 - Optical window; 3 - Infrared focal plane assembly, 301 - Detector window, 302 - Detector cold stop, 303 - Detector focal plane;

[0040] 4 - Flexible seal assembly, 401 - Flexible bellows, 402 - Sealing ring, 403 - Low - temperature adhesive layer or welding layer;

[0041] 5 - Housing; 7 - Low - temperature cold source; 8 - Flexible cold chain, 801 - Thermal conduction lock, 802 - Second graphite film; 9 - Support cold plate;

[0042] 10 - Heat - insulation support base, 1001 - Metal support base, 1002 - First cushion column, 1003 - Second cushion column;

[0043] 11 - Vacuum valve; 12 - Vacuum gauge;

[0044] 13 - First graphite film; 14 - Heat - insulation material; 15 - Temperature sensor; 16 - Electrical connector; 17 - Flange; 18 - Image - plane trimming gasket; 19 - Front - mounted telescopic system. Detailed implementation manners

[0045] The present utility model will be further described below in conjunction with the drawings and exemplary embodiments.

[0046] Refer to Figures 1 to 8 , a relay cryogenic infrared detection system, including a flange 17, a housing 5 and a low - temperature cold - source group.

[0047] Refer to Figure 2 、 Figure 3 , one end of the flange 17 is connected to the housing 5, and the other end is used to connect the front - mounted telescopic system 19. An image - plane trimming gasket 18 is arranged between the flange 17 and the front - mounted telescopic system 19. By adjusting the image - plane trimming gasket 18, the relay infrared optical lens 1 is made to match the telescopic optical system 100%.

[0048] The housing 5 adopts a Dewar box. The interior of the housing 5 is a vacuum chamber. An optical light - inlet hole, an optical light - outlet, a vacuum valve 11 and a vacuum gauge 12 communicating with the vacuum chamber are arranged on the side wall; an optical window 2 is arranged in the optical light - inlet hole through a vacuum sealant; an infrared focal plane assembly 3 is arranged in the optical light - outlet through a group of flexible seal assemblies 4; the vacuum valve 11 is connected to a molecular pump group through a KF flange and is used to evacuate the vacuum chamber; the vacuum gauge 12 is used to detect the vacuum degree of the vacuum chamber in real - time.

[0049] Refer to Figure 1 、 Figure 2 、 Figure 4 The relay infrared optical lens 1 includes a lens frame and four reflectors (the first reflector 101, the second reflector 102, the third reflector 103, and the fourth reflector 104) sequentially arranged on the lens frame along the optical path. The lens frame includes a frame body 105 and a cover plate 106. The four reflectors are all free-form off-axis reflectors and are arranged on the frame body 105 through fastening screws; the four reflectors, the lens frame, and the fastening screws are all made of the same material (6061-T651 aluminum alloy), ensuring that the thermal deformations of the reflectors and the lens frame change proportionally, which can eliminate the adverse effects of severe surface deformation caused by the extrusion or stretching of the structure on the reflectors due to the use of different materials for the structure and the reflectors. In theory, athermalization of the system can be achieved.

[0050] Refer to Figure 5 Two temperature sensors 15 are arranged on the back of each reflector for real-time monitoring of the temperature change of the reflector during the refrigeration process. The temperature sensors 15 are connected to an external host computer through electrical connectors 16 arranged on the housing 5 to achieve real-time monitoring; the outer surface of the lens frame is coated with a first graphite film 13 with a thickness of 1.2 mm for making the temperature fields of the four reflectors more uniform; heat insulation materials 14 are arranged on the first graphite film 13 and the inner wall of the vacuum chamber. The heat insulation materials 14 are of a multi-layer structure and the outer surface is provided with a double-sided aluminized polyester film for preventing radiative heat transfer between the two, thereby greatly shortening the system cooling time; three heat insulation support seats 10 are arranged between the bottom surface of the lens frame and the inner wall of the vacuum chamber; Refer to Figure 6 Each heat insulation support seat 10 includes a metal support seat 1001. The metal support seat 1001 is a cylinder, and a plurality of through holes are arranged on the side wall. A first cushion column 1002 is coaxially arranged at the upper end of the metal support seat 1001, and two second cushion columns 1003 are symmetrically arranged at the lower end. The metal support seat 1001 is made of titanium alloy for ensuring the structural stability, and the first cushion column 1002 and the two second cushion columns 1003 are both made of glass fiber reinforced plastic for blocking heat conduction.

[0051] Refer to Figure 2 、 Figure 4 The infrared focal plane assembly 3 includes a detector window 301, a detector cold stop 302, and a detector focal plane 303 sequentially arranged along the optical path; one end of the infrared focal plane assembly 3 close to the detector window 301 is arranged in the optical light outlet through a set of flexible sealing assemblies 4.

[0052] Refer to Figure 1 、 Figure 4, the outgoing light of the front telescopic system 19 sequentially passes through the inner hole of the flange 17, the optical window 2, the first mirror 101, the second mirror 102, the third mirror 103, the fourth mirror 104, the detector window 301, and the detector cold stop 302, and then focuses on the detector focal plane 303.

[0053] Refer to Figure 5 , each cryogenic cold source group includes two cryogenic cold sources 7 located outside the housing 5. The output end of each cryogenic cold source 7 is sequentially connected to the flexible cold chain 8 and the support cold plate 9 on the bottom surface of the frame 105. The two cryogenic cold sources 7 are symmetrically arranged along the flexible cold chain 8 to cancel out vibrations; the support cold plate 9 is covered under the first graphite film 13 and is made of copper or brass; the flexible cold chain 8 passes through the housing 5, and a set of flexible seal components 4 is arranged between the flexible cold chain 8 and the housing 5.

[0054] The cryogenic cold source 7 adopts a counter-type Stirling refrigerator, or a pulse tube refrigerator can also be used; the flexible cold chain 8 includes a parallel thermal conduction lock 801 and a second graphite film 802, and the thickness of the second graphite film 802 is 1.8 mm.

[0055] Refer to Figure 7 , each set of flexible seal components 4 includes a flexible bellows 401; one end of the two flexible bellows 401 is connected to the housing 5, and a sealing ring 402 is arranged between the flexible bellows 401 and the housing 5. The other ends are respectively connected to the infrared focal plane assembly 3 and the flexible cold chain 8 by a low-temperature adhesive layer or a welding layer 403. The flexible seal component 4 has a multi-dimensional adjustment function, which can realize the micro-angle and micro-displacement adjustment between the optical lens and the focal plane, thereby improving the imaging quality or detection performance of the system.

[0056] The optical window 2, the relay infrared optical lens 1, and the infrared detector assembly are in the same horizontal plane to ensure that the optical axis is in one horizontal plane.

[0057] The B310 star image obtained after the embodiment of the present invention is docked with the front telescopic system 19 is as Figure 8 shown.

[0058] The main technical indicators after the embodiment of the present invention is docked with the front telescopic system 19 are shown in Table 1:

[0059] Table 1

[0060] Serial number Parameter Value 1 Spectral range 7.7μm to 9.5μm 2 Detection sensitivity <![CDATA[5×10 -16 W / cm 2 @SNR=5]]> 3 Focal length 4.8m 4 F number 2

[0061] The working temperature range of the front telescopic system 19 is -25 to 30 °C (ambient temperature). It is a coaxial reflective optical system. The optical path is folded to the embodiment of the present invention through a folding mirror. The main parameters of the front telescopic system 19 are shown in Table 2:

[0062] Table 2

[0063] Serial number Parameter Value 1 Spectral range Full spectral range (mirror) 2 Aperture 2.4m 3 Focal length 19.2m 4 Durable focal plane 107 size (38.4 ± 1 mm) × (30.7 ± 1 mm)

[0064] In the embodiment of the utility model, the relay infrared optical lens 1 operates in a vacuum low-temperature environment with a vacuum degree lower than 5×10 -3 Pa and a temperature lower than 100K, and the cold source is provided by two opposed Stirling refrigerators for refrigeration. The main technical indicators of the relay infrared optical lens 1 in the embodiment of the utility model are shown in Table 3:

[0065] Table 3

[0066]

[0067]

[0068] The refrigerated infrared focal plane assembly 3 is used, and the detector focal plane 303 is refrigerated by its own small Stirling refrigerator to make it operate in a low-temperature environment not higher than 70K.

Claims

1. A relay low-temperature infrared detection system, characterized by: It comprises a flange (17), a shell (5) and at least one low-temperature cooling source group; One end of the flange (17) is connected to the housing (5), and the other end is provided with an image plane trimming gasket (18) for connecting to a front telescopic system (19); The interior of the shell (5) is a vacuum cavity, and an optical light inlet and an optical light outlet connected to the vacuum cavity are provided on the side wall; a relay infrared optical lens (1) is provided in the vacuum cavity, and the relay infrared optical lens (1) includes a lens frame and a plurality of reflectors arranged on the lens frame in sequence along the optical path, and the plurality of reflectors are all free-form off-axis reflectors and are made of the same material as the lens frame; an optical window (2) and an infrared focal plane assembly (3) are respectively provided in the optical light inlet and the optical light outlet, and a group of flexible sealing assemblies (4) are provided between the optical light outlet and the infrared focal plane assembly (3); the outgoing light of the front telescope system (19) passes through the inner hole of the flange (17), the optical window (2), and the plurality of reflectors in sequence before reaching the infrared focal plane assembly (3); Each of the reflectors is provided with at least one temperature sensor (15); the outer surface of the mirror frame is coated with a first graphite film (13); a heat insulation component is provided between the first graphite film (13) and the inner wall of the vacuum chamber; and at least three heat insulation support seats (10) are provided between the bottom surface of the mirror frame and the inner wall of the vacuum chamber; The low-temperature cooling source group includes two low-temperature cooling sources (7) located outside the shell (5), and the output end of each low-temperature cooling source (7) is connected to the mirror frame via a flexible cold chain (8); the flexible cold chain (8) passes through the shell (5), and a group of flexible sealing components (4) is provided between the flexible cold chain (8) and the shell (5).

2. A relay low-temperature infrared detection system according to claim 1, characterized in that: The number of the plurality of reflectors is specifically four, and the four reflectors and the mirror frame are all made of aluminum alloy.

3. A relay low-temperature infrared detection system according to claim 2, characterized in that: A supporting cold plate (9) is provided on the bottom surface of the mirror frame, the supporting cold plate (9) is wrapped with the first graphite film (13), and the supporting cold plate (9) is connected to the flexible cold chain (8).

4. The relay low-temperature infrared detection system according to claim 3, characterized in that: The flexible cold chain (8) includes a heat-conducting lock (801) and a second graphite film (802) connected in parallel.

5. A relay low-temperature infrared detection system according to any one of claims 1 to 4, characterized in that: The heat insulation component comprises two groups of heat insulation materials (14) respectively arranged on the first graphite film (13) and the inner wall of the vacuum chamber, and double-sided aluminum-plated polyester films respectively arranged on the outer surfaces of the two groups of heat insulation materials (14).

6. The relay low-temperature infrared detection system according to claim 5, characterized in that: Each group of the flexible sealing components (4) comprises a flexible bellows (401) and a sealing ring (402); one end of each of the two flexible bellows (401) is connected to the housing (5), and a sealing ring (402) is provided between the two flexible bellows and the housing (5); the other ends are respectively connected to the infrared focal plane component (3) and the flexible cold chain (8).

7. The relay low-temperature infrared detection system according to claim 5, characterized in that: Each of the heat-insulating support seats (10) comprises a metal support seat (1001), which is a cylindrical body with a plurality of through holes provided on its side wall. A first pad column (1002) is coaxially provided on the upper end of the metal support seat (1001), and two second pad columns (1003) are symmetrically provided on the lower end. The metal support seat (1001) is made of titanium alloy, and the first pad column (1002) and the two second pad columns (1003) are both made of glass fiber reinforced plastic.

8. The relay low-temperature infrared detection system according to claim 5, characterized in that: The optical window (2) is arranged in the optical light inlet through a vacuum sealant; the infrared focal plane assembly (3) comprises a detector window (301), a detector cold stop (302), and a detector focal plane (303) arranged in sequence along the light path; and one end of the infrared focal plane assembly (3) close to the detector window (301) is arranged in the optical light outlet.

9. The relay low-temperature infrared detection system according to claim 5, characterized in that: A vacuum valve (11) and a vacuum gauge (12) communicating with the vacuum chamber are provided on the side wall of the housing (5); the vacuum valve (11) is connected to a molecular pump group via a KF flange for evacuating the vacuum chamber; the vacuum gauge (12) is used to detect the vacuum degree of the vacuum chamber in real time.

10. The relay low-temperature infrared detection system according to claim 5, characterized in that: An electrical connector (16) is provided on the housing (5), the input end of the electrical connector (16) is respectively connected to all the temperature sensors (15), and the output end is used to connect to an external host computer.

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