A device for testing the micro-vibration of the cryogenic cold head of a refrigerator

Abstract

The device for testing the micro-vibration of the cryogenic cold head of a refrigerator provided by the present invention makes a laser beam incident on a four-quadrant detector, collects the laser intensities on four pixels, performs difference and sum calculations to obtain the offset of the laser center, and infers the displacement offset of the cryogenic cold head when the refrigerator is working, and tests its micro-vibration. This testing method can solve the problem of micro-vibration testing of the cryogenic cold head (40K-120K) of the refrigerator, and at the same time can directly test the micro-displacement of the detector after the infrared detector Dewar is coupled to the cryogenic cold head.

Description

Technical Field

[0001] The invention relates to the technical field of cryogenic cold heads, and in particular to a device for testing micro-vibration of a cryogenic cold head of a refrigerator. Background Art

[0002] Infrared imaging and hyperspectral cameras are composed of optics, infrared detectors, refrigerators, and acquisition circuits. The infrared detector is coupled to the cryogenic cold head of the refrigerator. The cryogenic cold head of the refrigerator provides a low temperature (40K-120K) environment for the infrared detector, reducing the dark current of the infrared detector to enable it to work normally. The refrigerator generally consists of a compressor and a cold head. The cryogenic cold head is the key part with the lowest temperature and coupled with the infrared detector. The tiny vibration of the cryogenic cold head caused by the compressor pressure wave or the moving parts of the cold head itself is an inherent characteristic of the refrigerator. If the cryogenic cold head transmits micro-vibrations exceeding a certain range to the infrared detector, it will cause the infrared camera imaging to be blurred and the spectral resolution to decrease. The high requirements for imaging and spectral resolution of high-precision infrared cameras, especially satellite-borne infrared detectors, put forward the goal of reducing the micro-vibration of the cryogenic cold head of the refrigerator as much as possible. A high-precision and reliable method is urgently needed to test the micro-vibration of the cryogenic cold head to evaluate its micro-vibration level.

[0003] At present, the normal temperature components of refrigerators are tested using force and acceleration sensors, but the cryogenic cold head cannot be tested in the above way due to its inherent characteristics. First, the force sensor needs to be rigidly connected to the object being tested, and the micro-vibration force of the object being tested is tested by the reaction force; the cryogenic cold head is a thin-walled cylindrical body with a thickness of only 3-10mm and no mounting holes. It cannot be rigidly connected to the force sensor, and the micro-vibration of the cryogenic cold head cannot be tested by the reaction force. Secondly, whether it is piezoelectric, piezoresistive, or coil-type acceleration sensors, the operating temperature range is -50℃~85℃, and the temperature of the cryogenic cold head is 40K-120K (ie -233℃~153℃). The acceleration sensor cannot work at this temperature or the test results are inaccurate. Summary of the invention

[0004] In view of this, it is necessary to provide a high-precision and reliable device for testing the micro-vibration of the cryogenic cold head of a refrigerator to evaluate the micro-vibration level of the cryogenic cold head.

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

[0006] A device for testing the micro-vibration of a cryogenic cold head of a refrigerator, comprising: a refrigerator compressor (1), a refrigerator cryogenic cold head (2), a four-quadrant detector dewar (3), a four-quadrant detector (4), an aperture (5), a collimator (6), a collimated laser (7), a three-dimensional precision optical adjustment frame (8), a preamplifier (9), a signal processing module (10), a suspension frame (11), an optical vibration isolation platform (12) and a refrigerator controller (13); wherein: the refrigerator compressor (1) and the refrigerator cryogenic cold head (2) are fixedly connected to form a refrigerator, and the refrigerator controller (13) controls the operation of the refrigerator. The four-quadrant detector (4) is arranged in the four-quadrant detector dewar (3), the four-quadrant detector dewar (3) is coupled with the refrigerator cryogenic cold head (2) and maintains vacuum, during micro-vibration test, the refrigerator compressor (1) and the refrigerator cryogenic cold head (2) are respectively suspended on the suspension frame (11) in a free state, the aperture (5), the collimator (6) and the three-dimensional precision optical adjustment frame (8) are fixed on the optical vibration isolation platform (12), and the collimator laser (7) is installed on the three-dimensional precision optical adjustment frame (8) and placed at the focal position of the collimator (6);

[0007] After the collimated laser (7) emits laser light, it is converted into parallel light through the collimator (6), and then shaped into a circular laser spot (15) after passing through the aperture (5). The circular laser spot (15) is irradiated onto the four-quadrant detector (4) through the window of the four-quadrant detector dewar (3). After the four-quadrant detector (4) detects the laser signal, the signal is amplified by the preamplifier (9) and then transmitted to the signal processing module (10) for signal analysis and processing.

[0008] In some of the embodiments, the refrigerator compressor (1) and the refrigerator cryogenic cold head (2) are fixedly connected by a welding process.

[0009] In some embodiments, the four-quadrant detector dewar (3) includes a first vacuum portion coupled to the four-quadrant detector (4) and a second vacuum portion plug-in coupled to the cryogenic cold head (2) of the refrigerator.

[0010] In some of the embodiments, the four-quadrant detector (4) is bonded to the four-quadrant detector dewar (3) by low-temperature glue, and thermal grease is filled between the coupling surface of the four-quadrant detector dewar (3) and the cryogenic cold head (2) of the refrigerator.

[0011] Some of the embodiments further include a spring (14), and the refrigerator compressor 1 and the refrigerator low-temperature cold head 2 are respectively hung on the suspension frame (11) through the spring (14) so ​​that the refrigerator is in a free state.

[0012] In some of the embodiments, the aperture (5), the collimator (6) and the three-dimensional precision optical adjustment frame (8) are fixed to the optical vibration isolation platform (12) by screws.

[0013] In some embodiments, the four-quadrant detector (4) is a silicon four-quadrant detector, which is divided into four right-angle fan-shaped silicon-based photodetectors with equal areas, the same shapes and symmetrical positions.

[0014] In some of the embodiments, the right-angle fan-shaped silicon-based photodetector has a response wavelength of 400nm-1100nm, a diameter of 4mm, and a cross gap of 20μm.

[0015] In some embodiments, the four quadrants of the silicon four-quadrant detector are represented by A, B, C, and D respectively. Any right-angled fan-shaped silicon-based photoelectric detector is independent of each other and is respectively located in the above four quadrants. Each right-angled fan-shaped silicon-based photoelectric detector represents a quadrant. The right-angled fan-shaped silicon-based photoelectric detector can receive a certain amount of light energy and output a certain photovoltage. The output voltage is proportional to the light power received by the detector. The corresponding output signals are VA, VB, VC, and VD. The circular laser spot (15) is irradiated on the photosensitive surface of the four-quadrant detector (4) through the window of the four-quadrant detector Dewar (3). The spot is divided into four parts by the four quadrants, and corresponding electrical signals with different amplitudes are output. The displacement change signals in two directions are VX and VY:

[0016]

[0017]

[0018] By adopting the above technical solution, the technical effects achieved by the present invention are as follows:

[0019] The device provided by the present invention is used for testing the micro-vibration of the cryogenic cold head of a refrigerator. The laser beam is incident on a four-quadrant detector, and the laser intensities on four pixels are collected for difference and sum calculation to obtain the offset of the laser center, and the displacement offset of the cryogenic cold head when the refrigerator is working is inferred to test its micro-vibration. This testing method can solve the problem of micro-vibration testing of the cryogenic cold head (40K-120K) of the refrigerator. At the same time, the micro-displacement of the detector after the infrared detector Dewar is coupled to the cryogenic cold head can be directly tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of a device for testing micro-vibration of a cryogenic cold head of a refrigerator provided by an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the refrigerator structure for testing a cryogenic cold head micro-vibration device of a refrigerator provided in an embodiment of the present invention.

[0023] Figure 3 A schematic diagram of the testing principle of a micro-vibration device for testing a cryogenic cold head of a refrigerator provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] See also Figure 1, which is a schematic diagram of the structure of a device for testing the micro-vibration of a cryogenic cold head of a refrigerator provided by an embodiment of the present invention, comprising: a refrigerator compressor (1), a refrigerator cryogenic cold head (2), a four-quadrant detector dewar (3), a four-quadrant detector (4), an aperture (5), a collimator (6), a collimated laser (7), a three-dimensional precision optical adjustment frame (8), a preamplifier (9), a signal processing module (10), a suspension frame (11), an optical vibration isolation platform (12) and a refrigerator controller (13). The connection relationship between the above-mentioned components is described in detail below.

[0029] The refrigerator compressor (1) and the refrigerator low temperature cold head (2) are fixedly connected to form a refrigerator, and the operation of the refrigerator is controlled by the refrigerator controller (13). Specifically, the refrigerator compressor (1) and the refrigerator low temperature cold head (2) are fixedly connected by a welding process.

[0030] The four-quadrant detector (4) is arranged in the four-quadrant detector dewar (3), and the four-quadrant detector dewar (3) is coupled with the cryogenic cold head (2) of the refrigerator and maintains a vacuum. Specifically, the four-quadrant detector dewar (3) includes a first vacuum part coupled with the four-quadrant detector (4) and a second vacuum part plug-in-coupled with the cryogenic cold head (2) of the refrigerator.

[0031] Furthermore, the four-quadrant detector (4) is bonded to the four-quadrant detector dewar (3) by low-temperature glue, and thermal grease is filled between the coupling surface of the four-quadrant detector dewar (3) and the cryogenic cold head (2) of the refrigerator.

[0032] See also Figure 2 , which is a schematic structural diagram of the four-quadrant detector (4) provided in an embodiment of the present invention, wherein the four-quadrant detector (4) is a silicon four-quadrant detector, and the four-quadrant detector is divided into four right-angle fan-shaped silicon-based photodetectors with equal areas, the same shapes and symmetrical positions.

[0033] In some of the embodiments, the right-angle fan-shaped silicon-based photodetector has a response wavelength of 400nm-1100nm, a diameter of 4mm, and a cross gap of 20μm.

[0034] The refrigerator compressor (1) and the refrigerator cryogenic cold head (2) are respectively suspended on the suspension frame (11) in a free state. Specifically, the refrigerator compressor 1 and the refrigerator cryogenic cold head 2 are respectively suspended on the suspension frame (11) through the spring (14) so ​​that the refrigerator is in a free state.

[0035] The diaphragm (5), the collimator (6) and the three-dimensional precision optical adjustment frame (8) are fixed on the optical vibration isolation platform (12). Specifically, the diaphragm (5), the collimator (6) and the three-dimensional precision optical adjustment frame (8) are fixed on the optical vibration isolation platform (12) by screws.

[0036] The collimating laser (7) is installed behind the three-dimensional precision optical adjustment frame (8) and is placed at the focal position of the parallel light tube (6).

[0037] The working mode of the above-mentioned device for testing the micro-vibration of the cryogenic cold head of the refrigerator is as follows:

[0038] After the collimated laser (7) emits laser light, it is converted into parallel light through the collimator (6), and then shaped into a circular laser spot (15) after passing through the aperture (5). The circular laser spot (15) is irradiated onto the four-quadrant detector (4) through the window of the four-quadrant detector dewar (3). After the four-quadrant detector (4) detects the laser signal, the signal is amplified by the preamplifier (9) and then transmitted to the signal processing module (10) for signal analysis and processing.

[0039] Furthermore, the diameter of the laser beam emitted by the collimated laser (7) is 2 mm, which is half the diameter of the four-quadrant detector.

[0040] It can be understood that the circular laser spot 15 is irradiated onto the photosensitive surface of the four-quadrant detector 4 through the window of the four-quadrant detector Dewar 3, and the laser spot is divided into four parts by four quadrants, which output electrical signals of different amplitudes accordingly, and the offset size and offset azimuth of the target relative to the optical axis are measured using the sum and difference circuit.

[0041] See also Figure 3 , which is a schematic diagram of the test principle of a micro-vibration device for testing a cryogenic cold head of a refrigerator provided in an embodiment of the present invention.

[0042] Furthermore, the four quadrants of the silicon four-quadrant detector are represented by A, B, C, and D respectively. Any right-angled fan-shaped silicon-based photoelectric detector is independent of each other and is respectively located in the above four quadrants. Each right-angled fan-shaped silicon-based photoelectric detector represents a quadrant. The right-angled fan-shaped silicon-based photoelectric detector can receive a certain amount of light energy and output a certain photovoltage. The output voltage is proportional to the light power received by the detector. The corresponding output signals are VA, VB, VC, and VD. The circular laser spot (15) is irradiated on the photosensitive surface of the four-quadrant detector (4) through the window of the four-quadrant detector Dewar (3). The spot is divided into four parts by four quadrants, and corresponding electrical signals with different amplitudes are output. The displacement change signals in two directions are VX and VY:

[0043]

[0044]

[0045] The device provided by the present invention is used for testing the micro-vibration of the cryogenic cold head of a refrigerator. The laser beam is incident on a four-quadrant detector, and the laser intensities on four pixels are collected for difference and sum calculation to obtain the offset of the laser center, and the displacement offset of the cryogenic cold head when the refrigerator is working is inferred to test its micro-vibration. This testing method can solve the problem of micro-vibration testing of the cryogenic cold head (40K-120K) of the refrigerator. At the same time, the micro-displacement of the detector after the infrared detector Dewar is coupled to the cryogenic cold head can be directly tested.

[0046] The above are only preferred embodiments of the present invention, and only specifically describe the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention, and other specific implementations of the present invention that can be associated with by technicians in this field without creative labor, should be included in the scope of protection of the present invention.

Claims

1. A device for testing the micro-vibration of a cryogenic cold head of a refrigerator, characterized in that: include: Refrigerator compressor (1), refrigerator cryogenic cold head (2), four-quadrant detector dewar (3), four-quadrant detector (4), aperture (5), collimator (6), collimated laser (7), three-dimensional precision optical adjustment frame (8), preamplifier (9), signal processing module (10), suspension frame (11), optical vibration isolation platform (12) and refrigerator controller (13); wherein: The refrigerator compressor (1) and the refrigerator cryogenic cold head (2) are fixedly connected to form a refrigerator, and the refrigerator controller (13) controls the operation of the refrigerator. The four-quadrant detector (4) is arranged in the four-quadrant detector dewar (3), and the four-quadrant detector dewar (3) is coupled with the refrigerator cryogenic cold head (2) and maintains a vacuum. During the micro-vibration test, the refrigerator compressor (1) and the refrigerator cryogenic cold head (2) are respectively suspended on the suspension frame (11) in a free state. The diaphragm (5), the collimator (6) and the three-dimensional precision optical adjustment frame (8) are fixed on the optical vibration isolation platform (12). The collimator laser (7) is installed behind the three-dimensional precision optical adjustment frame (8) and placed at the focus position of the collimator (6). After the collimated laser (7) emits laser light, it is converted into parallel light through the collimator (6), and then shaped into a circular laser spot (15) after passing through the aperture (5). The circular laser spot (15) is irradiated onto the four-quadrant detector (4) through the window of the four-quadrant detector Dewar (3). After the four-quadrant detector (4) detects the laser signal, the signal is amplified by the preamplifier (9) and then transmitted to the signal processing module (10) for signal analysis and processing; The refrigerator compressor (1) and the refrigerator low-temperature cold head (2) are fixedly connected by a welding process; The four-quadrant detector dewar (3) comprises a first vacuum part coupled to the four-quadrant detector (4) and a second vacuum part plug-in coupled to the cryogenic cold head (2) of the refrigerator.

2. The device for testing the micro-vibration of the cryogenic cold head of a refrigerator according to claim 1, characterized in that: The four-quadrant detector (4) is bonded in the four-quadrant detector dewar (3) by low-temperature glue, and thermal grease is filled between the coupling surface of the four-quadrant detector dewar (3) and the cryogenic cold head (2) of the refrigerator.

3. The device for testing the micro-vibration of the cryogenic cold head of a refrigerator according to claim 1, characterized in that: It also includes a spring (14), and the refrigerator compressor 1 and the refrigerator low-temperature cold head 2 are respectively hung on the suspension frame (11) through the spring (14) so ​​that the refrigerator is in a free state.

4. The device for testing the micro-vibration of a cryogenic cold head of a refrigerator according to claim 1, characterized in that: The diaphragm (5), the collimator (6) and the three-dimensional precision optical adjustment frame (8) are fixed on the optical vibration isolation platform (12) by means of screws.

5. The device for testing the micro-vibration of a cryogenic cold head of a refrigerator according to claim 1, characterized in that: The four-quadrant detector (4) is a silicon four-quadrant detector, which is divided into four right-angled sector-shaped silicon-based photoelectric detectors with equal areas, the same shapes and symmetrical positions.

6. The device for testing the micro-vibration of the cryogenic cold head of a refrigerator according to claim 5, characterized in that: The right-angle sector-shaped silicon-based photoelectric detector has a response wavelength of 400nm-1100nm, a diameter of 4mm, and a cross gap of 20μm.

7. The device for testing the micro-vibration of a cryogenic cold head of a refrigerator according to claim 5, characterized in that: The four quadrants of the silicon four-quadrant detector are represented by A, B, C, and D respectively. Any right-angled fan-shaped silicon-based photoelectric detector is independent of each other and is respectively located in the above four quadrants. Each right-angled fan-shaped silicon-based photoelectric detector represents a quadrant. The right-angled fan-shaped silicon-based photoelectric detector can receive a certain amount of light energy and output a certain photovoltage. The output voltage is proportional to the light power received by the detector. The corresponding output signals are VA, VB, VC, and VD. The circular laser spot (15) is irradiated on the photosensitive surface of the four-quadrant detector (4) through the window of the four-quadrant detector Dewar (3). The spot is divided into four parts by the four quadrants, and corresponding electrical signals with different amplitudes are output. The displacement change signals in two directions are VX and VY:

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