CN109030358B - System and method for detecting weak infrared signal based on coaxial cavity microwave resonance principle - Google Patents
System and method for detecting weak infrared signal based on coaxial cavity microwave resonance principle Download PDFInfo
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- CN109030358B CN109030358B CN201810856245.2A CN201810856245A CN109030358B CN 109030358 B CN109030358 B CN 109030358B CN 201810856245 A CN201810856245 A CN 201810856245A CN 109030358 B CN109030358 B CN 109030358B
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Abstract
The invention provides a system and a method for detecting weak infrared signals based on a coaxial cavity microwave resonance principle, which comprises a sapphire window, an optical frequency division system, a coaxial cavity infrared signal detection system, a data extraction and processing system and a vacuum low-temperature cabin, wherein the sapphire window is embedded in a vacuum low-temperature cabin wall; the optical frequency division system comprises an off-axis paraboloid focusing mirror, an optical fiber and a multi-channel grating, and is used for carrying out total reflection transformation on an infrared signal to be detected and carrying out frequency division and channel division processing on the infrared signal to be detected through optical fiber transmission to the multi-channel grating; the coaxial cavity infrared signal detector detects infrared signals of each frequency band through position adjustment; the data acquisition and processing system is used for extracting and processing data of the coaxial cavity infrared signal detector in real time; the invention adopts the coaxial cavity infrared detector, the off-axis parabolic focusing mirror and the vacuum low-temperature chamber to convert a weak infrared signal into an observable and easily-detected microwave signal, and has the characteristics of wide test frequency band, high precision, good stability and low use and maintenance cost.
Description
Technical Field
The invention belongs to the field of optical radiation measurement, and particularly relates to a system and a method for detecting a weak infrared signal based on a coaxial cavity microwave resonance principle.
Background
The infrared detection has the advantages of high sensitivity, high stability, strong anti-interference performance and the like, and is mainly applied to guidance, reconnaissance, search, early warning, detection, tracking, all-weather forward-looking and night-vision, weapon aiming and the like in the military field at first. In recent years, infrared detection is one of the fastest-developing technologies, and infrared sensors are widely applied to various fields such as aerospace, astronomy, meteorology, military, industry, agriculture, medicine, transportation and the like at present, and play an irreplaceable important role in daily work and life. At present, two types of commonly used infrared detectors are mainly used, one type is a thermal detector, such as a bolometer, a thermocouple, a thermopile, a pyroelectric detector and the like; the other is a photon detector, such as a photoconductive detector, a photovoltaic detector, a light emission-Schottky barrier detector and the like. However, such devices are susceptible to factors such as service time and environmental radiation during application, and the working performance of the devices fluctuates greatly, and although the devices can be corrected by periodic calibration, the devices still have a large influence on the detection of infrared signal radiation performance at the exit pupil of the detector.
The accurate measurement of weak infrared signals is always a difficult point to be solved urgently, and although a mature infrared signal detection technology exists at present, particularly a tellurium-cadmium-mercury MCT infrared detector appears, the development of the infrared detection technology is greatly promoted. However, it has the following disadvantages: (1) the separation of the liquid line and the solid line of the phase diagram is large, and the radial and longitudinal components are uniformly distributed due to segregation; (2) the high Hg pressure makes the large-diameter crystal difficult to grow and the lattice structure integrity is poor; (3) the repetitive productivity is low. Due to the defects, the application of the MCT infrared detector on weak infrared signals is restricted, so that the MCT infrared detector can only realize-70 dBm/cm in a liquid nitrogen environment2Can not easily realize the detection of-70 dBm/cm2The following detection of a weaker infrared signal.
In summary, the conventional infrared signal detection technology has a small detection range, and the technology and cost limit the use conditions and application range thereof. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle converts a weak infrared signal to be detected which is difficult to detect into a microwave signal which is small in range and easy to observe. Therefore, it is very meaningful to provide a device and a method for detecting a weak infrared signal based on a coaxial cavity microwave resonance principle.
Disclosure of Invention
The invention aims to provide a device and a method for detecting weak infrared signals based on a coaxial cavity microwave resonance principle, aiming at the defects of the existing device for detecting weak infrared signals. The infrared sensitizing dye has different response characteristics under different infrared signal radiation, the coaxial resonant cavity with concentrated field intensity and high quality factor is adopted to detect the response characteristics of the infrared sensitizing dye, an infrared radiation power signal is converted into a microwave signal, and the high-sensitivity detection of a weak infrared signal is realized.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the weak infrared signal detection device based on the coaxial cavity microwave resonance principle comprises a vacuum low-temperature cabin 10, a sapphire window 9 embedded in the wall of the vacuum low-temperature cabin, an optical frequency division system 1, a coaxial cavity infrared signal detection system 2 and a data acquisition and processing system, wherein the optical frequency division system and the coaxial cavity infrared signal detection system are both positioned in the vacuum low-temperature cabin, the optical frequency division system 1 sequentially comprises an off-axis paraboloid focusing mirror, an optical fiber 17 and a multi-channel grating 18 along the infrared signal propagation direction, and the optical frequency division system is used for carrying out total reflection conversion on an infrared signal to be detected and carrying out frequency division section and channel division processing on the infrared signal to be detected through optical fiber transmission to the multi-channel grating; the coaxial cavity infrared signal detection system carries out position adjustment through the multi-dimensional mobile platform to detect infrared signals of each channel and each frequency band; the data acquisition and processing system is used for extracting and processing data of the coaxial cavity infrared signal detection system in real time.
Preferably, the optical frequency division system 1 sequentially includes an infrared filter 11, an impurity light eliminating diaphragm 12, an off-axis paraboloid large focusing mirror 13, a field diaphragm 14, an off-axis paraboloid small focusing mirror 15, a light chopper 16, an optical fiber 17 and a multi-channel grating 18 along an infrared signal propagation direction, and the infrared filter 11 is closely attached to the rear end of the sapphire window 9; the stray light eliminating diaphragm 12 is positioned between the infrared filter 11 and the off-axis paraboloid large focusing mirror 13; a field diaphragm 14 is arranged at the focus between the off-axis paraboloid large focusing mirror 13 and the off-axis paraboloid small focusing mirror 15; a light chopper 16 is arranged between the off-axis paraboloid small focusing mirror 15 and the optical fiber 17; the multi-channel grating 18 is arranged at the rear end of the optical fiber 17; an infrared signal to be detected enters the vacuum low-temperature cabin through the sapphire window, is incident on the off-axis paraboloid large focusing mirror 13 through the infrared filter and the impurity-removing light diaphragm 12, is subjected to full-reflection transformation through the off-axis paraboloid large focusing mirror 13 and the off-axis paraboloid small focusing mirror 15, is transmitted to the multichannel grating 18 through the optical fiber 17 after being regulated and controlled by the light chopper 16, and is subjected to channel division and direction division processing through the multichannel grating 18.
Preferably, the off-axis paraboloid large focusing mirror 13 and the off-axis paraboloid small focusing mirror 15 adopt quartz as a substrate, and the surface of the substrate is plated with a gold or silver metal reflecting film and a dielectric protective film.
Preferably, the multi-channel grating 18 is made of sapphire, and can perform multi-channel frequency division processing on infrared signals of 2-6 μm, and the infrared wavelength range which can be passed by each channel is different, and the resolution is less than 200 nm.
As a preferred mode, the coaxial cavity infrared signal detection system comprises a coaxial resonant cavity 19, a multidimensional moving platform 21 and an infrared sensitizing material 20, wherein the coaxial resonant cavity 19 is fixed on the multidimensional moving platform 21, the coaxial resonant cavity 19 is made of brass, silver and gold metal film layers are sequentially coated on the inner surface and the outer surface of the coaxial resonant cavity, the working frequency range of the coaxial resonant cavity is 1-8GHz, the quality factor of the coaxial resonant cavity is more than 1 ten thousand, the coaxial resonant cavity has more than 6 available resonant frequencies, and a coaxial resonant cavity test hole 24 with the depth of 3.5mm is formed in the center of the top end of the coaxial resonant cavity and is used for placing the infrared sensitizing material 20; the multi-dimensional mobile platform can be adjusted in four dimensions of up-down, left-right, front-back and angle; the infrared sensitizing material 20 adopts a glass fiber reinforced plastic plate or quartz as a base body, and the bottom end of the base body is coated with infrared sensitizing material coatings with different response characteristics under different infrared irradiation powers.
As a preferred mode, the data acquisition and processing system comprises a vector network analyzer 3 and a program control computer 4, the vector network analyzer 3 is connected with a coaxial resonant cavity 19 through a microwave cable 8, the program control computer 4 is used for controlling the vector network analyzer 3 to extract microwave performance parameters of the coaxial resonant cavity at different positions through the program control, and calculating the dielectric constant and the loss tangent of the infrared sensitizing material according to the microwave resonance principle.
As a preferred mode, the inner surface of the vacuum low-temperature chamber is adhered with an infrared wave-absorbing material, and the working frequency range of the infrared wave-absorbing material covers near and middle infrared wave bands;
preferably, the system further comprises a liquid nitrogen circulating refrigerator 6 and a vacuum pump 7 which are respectively communicated to the interior of the vacuum low-temperature chamber 10, wherein the liquid nitrogen circulating refrigerator 6 is used for providing an ultralow-temperature environment for the interior of the vacuum low-temperature chamber 10, and the vacuum pump 7 adopts a molecular pump unit and can reduce the vacuum degree in the vacuum low-temperature chamber to 1 Pa.
In order to achieve the above object, the present invention further provides a method for detecting weak infrared signals by using the above device, comprising the following steps:
step 1: placing an optical frequency division system and a coaxial cavity infrared signal detection system in a vacuum low-temperature cabin, adjusting devices to ensure that an infrared signal detection circuit is smooth, connecting a program control computer and a vector network analyzer, connecting a coaxial resonant cavity and the vector network analyzer, connecting a liquid nitrogen circulating refrigerator and the vacuum low-temperature cabin, and connecting a vacuum pump and the vacuum low-temperature cabin;
step 2: starting a vacuumizing device, reducing the air pressure of the vacuum low-temperature cabin to be below 1Pa, and starting a liquid nitrogen circulating refrigerator to reduce the air pressure of the vacuum low-temperature cabin to-190 ℃;
and step 3: placing an infrared signal source in front of a sapphire window, enabling the infrared signal to enter a vacuum low-temperature cabin through the sapphire window, enabling the infrared signal to reach an off-axis paraboloid large focusing mirror after passing through an infrared filter and an impurity-removing light diaphragm, enabling the infrared signal to reach an off-axis paraboloid small focusing mirror through an off-axis paraboloid large focusing mirror and a field diaphragm to form a high-convergence collimated beam, then enabling the high-convergence collimated beam to be irradiated onto a multi-channel grating through an optical fiber after being regulated and controlled by a chopper, and finally enabling the infrared beam to be subjected to frequency division and channel division transmission through the multi-channel;
and 4, step 4: adjusting the multi-dimensional mobile platform to enable the coaxial resonant cavity to be positioned outside the multi-channel grating infrared signal transmission channel, testing the infrared sensitizing material positioned in the coaxial resonant cavity testing hole in the state by the aid of the process control computer and the vector network analyzer, and recording the dielectric constant of the infrared sensitizing material in the state as the dielectric constant of the infrared sensitizing material0Loss tangent is denoted tan0；
And 5: adjusting the multi-dimensional moving platform to enable the coaxial resonant cavity to be positioned on the multi-channel grating with the infrared wavelength of lambda1After the infrared sensitizing material is stabilized, the infrared sensitizing material in the state is tested by a process control computer and a vector network analyzer, and the dielectric constant of the infrared sensitizing material in the state is recorded as1Loss tangent is denoted tan1；
Step 6: calculating the change delta of the dielectric constant of the infrared sensitizing material before and after the irradiation of the opened infrared signal through the step 4 and the step 51Loss tangent change Δ tan1The calculation method is as follows:
Δ1＝1-0
Δtan1＝tan1-tan0
and 7: by changing the radiation power P of the infrared signal source, the infrared wavelength lambda under different radiation powers is obtained1Corresponding delta1And delta tan1Furthermore, the recorded data are counted and sorted to obtain the infrared wavelength lambda1Corresponding P-Delta1And P-delta tan1The data statistical table of (2);
and 8: adjusting the multi-dimensional moving platform to enable the coaxial resonant cavity to be positioned on the multi-channel grating with the infrared wavelength of lambda2After the channel direction is stabilized, repeating the step 5, the step 6 and the step 7 to obtain the infrared wavelength lambda2Corresponding P-Delta2And P-delta tan2The data statistical table of (2) is analogized in this way to obtain different infrared wavelengths as lambdanCorresponding P-DeltanAnd P-ΔtannThe data statistical table of (2);
and step 9: detecting the infrared signal source to be detected with unknown radiation power, and calculating different infrared wavelengths lambda under the radiation powernDelta in the channel directionnAnd delta tannAnd the different infrared wavelengths obtained by step 8 are referred to as lambdanCorresponding P-DeltanAnd P-delta tannAnd the data statistics table obtains the radiation power P of the light source to be detected, and finally, the frequency and power detection of the infrared signal to be detected is realized.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the weak infrared signal detection device based on the coaxial cavity microwave resonance principle, the outside of the vacuum low-temperature cabin can be connected with the liquid nitrogen circulating refrigerator and the vacuum pump, so that the vacuum low-temperature cabin is in an ultralow-temperature vacuum environment for a long time, and the influence of the infrared radiation of each device in an optical frequency division system and a coaxial cavity infrared signal detection system on a test result is avoided. In addition, the inner surface of the vacuum low-temperature chamber is adhered with a broadband infrared wave-absorbing material, so that the influence of the disordered reflection and scattering of infrared signals by each device in an optical frequency division system and a coaxial cavity infrared signal detection system on a detection result is avoided.
(2) The invention provides a weak infrared signal detection device based on a coaxial cavity microwave resonance principle, which introduces an infrared filter, a stray light eliminating diaphragm, an off-axis paraboloid large focusing mirror, an off-axis paraboloid small focusing mirror, a chopper, an optical fiber, a multi-channel grating and other devices into an adopted optical frequency division system. Wherein infrared filter hugs closely behind sapphire infrared window, can realize the multiple filtering to the infrared signal that awaits measuring, has avoided the influence of external environment to the weak infrared signal that awaits measuring. The stray light eliminating diaphragm is used for further filtering external interference signals and simultaneously performing beam arrangement on infrared signals to be detected, so that the influence of mixed and disorderly signals on the focusing effect of the rear-end off-axis parabolic focusing mirror on the infrared signals is avoided. The full-reflection conversion of the infrared signals is realized by adopting the off-axis paraboloid large focusing mirror and the off-axis paraboloid small focusing mirror, so that the wide-beam incident signals are converted into narrow-beam signals to be detected, and the detectable power density is improved. The light chopper and the optical fiber are adopted to respectively realize the pre-regulation and directional transmission of the infrared signal to be detected. The multichannel grating is adopted to realize channel division and direction division transmission of the infrared signals to be detected, the infrared signals with different wavelength ranges are transmitted along different channels and directions, the frequency division processing of the infrared signals to be detected is realized, and the resolution ratio can reach 200 nm.
(3) In the weak infrared signal detection device based on the coaxial cavity microwave resonance principle, the coaxial cavity infrared signal detection system is adopted to receive and detect infrared signals to be detected in all wave bands. The infrared sensitizing dye is adopted to replace the traditional MCT and a receiving device of a pyroelectric detector. Based on the characteristic that the infrared sensitizing dye has different responses under different infrared signal irradiation powers, the weak infrared signal is received and detected. The infrared signal receiving device has low cost and wide source, and is easy to coat on common substrate materials such as quartz, glass steel plates and the like to prepare the infrared signal receiving device with higher sensitivity. Adopt the coaxial resonant cavity that field intensity is concentrated, the figure of merit is high as infrared signal detection device, can turn into the microwave signal that can observe, easily detect with the infrared signal that detects the difficulty, its superiority lies in: because the infrared signal to be detected is weak, the infrared signal far exceeds the working range of the traditional infrared signal detection device, especially the power density is less than-70 dBm/cm2The coaxial resonant cavity has high quality factor, concentrated field intensity and high sensitivity, can convert weak infrared signals which are difficult to detect into microwave signals which have small variation range and are easy to observe by measuring the response characteristics of the infrared sensitizing dye under different infrared signal power radiations, and realizes the high-sensitivity and sensitive detection of the weak infrared signals.
(4) In the weak infrared signal detection device based on the coaxial cavity microwave resonance principle, the adopted data extraction and processing system consists of a vector network analyzer and a program control computer, wherein the vector network analyzer can realize the real-time extraction of the microwave performance parameters of the coaxial resonant cavity, and the program control computer calculates the microwave performance parameters extracted by the vector network analyzer according to the microwave resonance principle so as to obtain the dielectric constant and the loss tangent of the infrared sensitizing material under different states and realize the microwave method detection of the weak infrared signal to be detected.
Drawings
Fig. 1 is a schematic structural diagram of a weak infrared signal detection device based on a coaxial cavity microwave resonance principle.
Fig. 2 is a schematic structural diagram of an optical frequency division system provided by the present invention.
Fig. 3 is a schematic structural diagram of a coaxial cavity infrared signal detection system provided by the present invention.
Fig. 4 is a schematic view of a coaxial resonant cavity structure provided by the present invention.
Fig. 5 is a schematic structural diagram of the infrared sensitizing material provided by the present invention.
The system comprises an optical frequency division system 1, a coaxial cavity infrared signal detection system 2, a vector network analyzer 3, a program control computer 4, an infrared signal source 5, a liquid nitrogen circulating refrigerator 6, a vacuum pump 7, a microwave cable 8, a sapphire window 9, a vacuum low-temperature chamber 10, an infrared filter 11, an impurity-removing light diaphragm 12, an off-axis paraboloid large focusing mirror 13, a field diaphragm 14, an off-axis paraboloid small focusing mirror 15, a chopper 16, an optical fiber 17, a multi-channel grating 18, a coaxial resonant cavity 19, an infrared sensitizing material 20, a multi-dimensional moving platform 21, a coaxial resonant cavity outer conductor 22, a coaxial resonant cavity inner conductor 23, a coaxial resonant cavity test hole 24, a coaxial resonant cavity microwave connector 25, an infrared sensitizing material substrate 26 and an infrared sensitizing material coating 27.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As described in the background section, existing infrared detection techniques have not been able to fully achieve power densities less than-70 dBm/cm2The invention provides a weak infrared signal detection system and a method based on a coaxial cavity microwave resonance principle, which are required for detecting weak infrared signals and used for solving the problem.
As shown in fig. 1, the weak infrared signal detection device based on the coaxial cavity microwave resonance principle includes a vacuum low-temperature chamber 10, a sapphire window 9 embedded in a wall of the vacuum low-temperature chamber, an optical frequency division system 1, a coaxial cavity infrared signal detection system 2, a vector network analyzer 3, a program control computer 4, an infrared signal source 5, a liquid nitrogen circulating refrigerator 6, a vacuum pump 7 and a microwave cable 8, wherein the optical frequency division system 1 and the coaxial cavity infrared signal detection system 2 are all placed in the vacuum low-temperature chamber 10, and the optical frequency division system 1 is used for filtering, transforming, dividing frequency and processing directions of an infrared signal to be detected; the coaxial cavity infrared signal detection system 2 performs position adjustment through the multi-dimensional mobile platform to perform channel-by-channel and frequency-band-by-frequency test on the infrared signal to be detected after frequency division and direction division processing of the optical frequency division system 1; the vector network analyzer 3 and the program control computer 4 jointly form a data acquisition and processing system which is used for extracting and processing data of the coaxial cavity infrared signal detector 2 in real time; the liquid nitrogen circulating refrigerator 6 and the vacuum pump 7 are used for providing an ultralow-temperature vacuum environment for the vacuum low-temperature cabin 10 and reducing the influence of the external environment and the infrared radiation of the device on the test result.
The optical frequency division system 1 sequentially comprises an infrared filter 11, an impurity light eliminating diaphragm 12, an off-axis paraboloid large focusing mirror 13, a field of view diaphragm 14, an off-axis paraboloid small focusing mirror 15, a light chopper 16, an optical fiber 17 and a multi-channel grating 18 along the infrared signal propagation direction, wherein the infrared filter 11 is tightly attached to the rear end of a sapphire window, the working center wavelengths of the infrared filter 11 are respectively 2.8 mu m, 3.4 mu m, 4.6 mu m and 5.3 mu m, and the spectral bandwidths of the infrared filter 11 are respectively 130nm, 150nm, 100nm and 80 nm; the stray light eliminating diaphragm 12 is positioned between the infrared filter 11 and the off-axis paraboloid large focusing mirror 13, the aperture of the stray light eliminating diaphragm 12 is 75mm, and the aperture of the off-axis paraboloid large focusing mirror 13 is 100 mm; a field diaphragm 14 is arranged at a focus between the off-axis paraboloid large focusing mirror 13 and the off-axis paraboloid small focusing mirror 15, the standard field of view of the field diaphragm is 0.04 degrees, and the field diaphragm is used for eliminating the influence of the disordered reflected infrared signals of the off-axis paraboloid large focusing mirror 13 on a test result; the caliber of the off-axis paraboloid small focusing mirror 15 is 10 mm; a light chopper 16 is arranged between the off-axis paraboloid small focusing mirror 15 and the optical fiber 17; the multi-channel grating 18 is arranged at the rear end of the optical fiber 17; an infrared signal to be detected enters a vacuum low-temperature cabin 10 through a sapphire window 9, is incident on an off-axis paraboloid large focusing mirror 13 through an infrared filter 11 and an impurity-eliminating light diaphragm 12, is subjected to total reflection transformation through the off-axis paraboloid large focusing mirror 13 and an off-axis paraboloid small focusing mirror 15, is transmitted to a multichannel grating 18 through an optical fiber 17 after being regulated and controlled through a light chopper 16, and is subjected to channel division and direction division processing through the multichannel grating 18.
Preferably, the off-axis paraboloid large focusing mirror 13 and the off-axis paraboloid small focusing mirror 15 adopt quartz as a substrate, and the surfaces of the quartz are plated with a gold or silver metal reflecting film and a dielectric protective film.
Preferably, the multi-channel grating 18 is made of sapphire, and can perform multi-channel frequency division processing on infrared signals of 2-6 μm, and the infrared wavelength range which can be passed by each channel is different, and the resolution is less than 200 nm.
Preferably, the coaxial cavity infrared signal detection system 2 comprises a coaxial resonant cavity 19, a multidimensional moving platform 21 and an infrared sensitizing material 20, wherein the coaxial resonant cavity 19 is fixed on the multidimensional moving platform 21, the coaxial resonant cavity 19 is made of brass, the inner surface and the outer surface of the coaxial resonant cavity 19 are coated with silver and gold metal film layers in sequence, the working frequency range of the coaxial resonant cavity is 1-8GHz, the quality factor is more than 1 ten thousand, and more than 6 available resonant frequencies are provided. A coaxial resonant cavity testing hole 24 with the depth of 3.5mm is formed in the center of the top end of the coaxial resonant cavity 19 and used for placing the infrared sensitizing material 20; the multi-dimensional mobile platform is a common position adjusting tool in the market and can be obtained through purchase, and the multi-dimensional mobile platform 21 can be adjusted in four dimensions, namely up-down, left-right, front-back and angle; the infrared sensitizing material 20 adopts a glass fiber reinforced plastic plate or quartz as a base body, and the bottom end of the base body is coated with infrared sensitizing material coatings 27 with different response characteristics under different infrared radiation powers.
Preferably, the data acquisition and processing system comprises a vector network analyzer 3 and a program control computer 4, the vector network analyzer 3 is connected with the coaxial resonant cavity 19 through a microwave cable 8, the program control computer 4 controls the vector network analyzer 3 to extract microwave performance parameters of the coaxial resonant cavity 19 at different positions through a specific program, and calculates the dielectric constant and the loss tangent of the infrared sensitizing material 20 according to the microwave resonance principle.
Preferably, the inner surface of the vacuum low-temperature chamber 10 is adhered with an infrared wave-absorbing material, and the working frequency range of the infrared wave-absorbing material covers near and middle infrared wave bands;
the microwave detection method for weak infrared signals by using the device comprises the following steps:
step 1: placing an optical frequency division system and a coaxial cavity infrared signal detection system in a vacuum low-temperature cabin, adjusting devices to ensure that an infrared signal detection circuit is smooth, connecting a program control computer and a vector network analyzer, connecting a coaxial resonant cavity and the vector network analyzer, connecting a liquid nitrogen circulating refrigerator and the vacuum low-temperature cabin, and connecting a vacuum pump and the vacuum low-temperature cabin;
step 2: starting a vacuumizing device, reducing the air pressure of the vacuum low-temperature cabin to be below 1Pa, and starting a liquid nitrogen circulating refrigerator to reduce the air pressure of the vacuum low-temperature cabin to-190 ℃;
and step 3: placing an infrared signal source in front of a sapphire window, enabling the infrared signal to enter a vacuum low-temperature cabin through the sapphire window, enabling the infrared signal to reach an off-axis paraboloid large focusing mirror after passing through an infrared filter and an impurity-removing light diaphragm, enabling the infrared signal to reach an off-axis paraboloid small focusing mirror through an off-axis paraboloid large focusing mirror and a field diaphragm to form a high-convergence collimated beam, then enabling the high-convergence collimated beam to be irradiated onto a multi-channel grating through an optical fiber after being regulated and controlled by a chopper, and finally enabling the infrared beam to be subjected to frequency division and channel division transmission through the multi-channel;
and 4, step 4: adjusting the multi-dimensional mobile platform to enable the coaxial resonant cavity to be positioned outside the multi-channel grating infrared signal transmission channel, testing the infrared sensitizing material positioned in the coaxial resonant cavity testing hole in the state by the aid of the process control computer and the vector network analyzer, and recording the dielectric constant of the infrared sensitizing material in the state as the dielectric constant of the infrared sensitizing material0Loss tangent is denoted tan0；
And 5: adjusting the multi-dimensional moving platform to enable the coaxial resonant cavity to be positioned on the multi-channel grating with the infrared wavelength of lambda1After the infrared sensitizing material is stabilized, the infrared sensitizing material in the state is tested by a process control computer and a vector network analyzer, and the dielectric constant of the infrared sensitizing material in the state is recorded as1Loss tangent is denoted tan1；
Step 6: calculating the change delta of the dielectric constant of the infrared sensitizing material before and after the irradiation of the opened infrared signal through the step 4 and the step 51Loss tangent change Δ tan1The calculation method is as follows:
Δ1＝1-0
Δtan1＝tan1-tan0
and 7: by changing the radiation power P of the infrared signal source, the infrared wavelength lambda under different radiation powers is obtained1Corresponding delta1And delta tan1Furthermore, the recorded data are counted and sorted to obtain the infrared wavelength lambda1Corresponding P-Delta1And P-delta tan1The data statistical table of (2);
and 8: adjusting the multi-dimensional moving platform to enable the coaxial resonant cavity to be positioned on the multi-channel grating with the infrared wavelength of lambda2After the channel direction is stabilized, repeating the step 5, the step 6 and the step 7 to obtain the infrared wavelength lambda2Corresponding P-Delta2And P-delta tan2The data statistical table of (2) is analogized in this way to obtain different infrared wavelengths as lambdanCorresponding P-DeltanAnd P-delta tannThe data statistical table of (2);
and step 9: detecting an infrared signal source to be detected with unknown radiation power,calculating different infrared wavelengths lambda under the radiation powernDelta in the channel directionnAnd delta tannAnd the different infrared wavelengths obtained by step 8 are referred to as lambdanCorresponding P-DeltanAnd P-delta tannAnd the data statistics table obtains the radiation power P of the light source to be detected, and finally, the frequency and power detection of the infrared signal to be detected is realized.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (9)
1. Weak infrared signal detection device based on coaxial chamber microwave resonance principle, its characterized in that: the system comprises a vacuum low-temperature cabin (10), a sapphire window (9) embedded in the wall of the vacuum low-temperature cabin, an optical frequency division system (1), a coaxial cavity infrared signal detection system (2) and a data acquisition and processing system, wherein the optical frequency division system and the coaxial cavity infrared signal detection system are both positioned in the vacuum low-temperature cabin, the optical frequency division system (1) sequentially comprises an off-axis paraboloid focusing mirror, an optical fiber (17) and a multi-channel grating (18) along the infrared signal propagation direction, and the optical frequency division system (1) is used for carrying out total reflection transformation on an infrared signal to be detected and carrying out frequency division section and channel division processing on the infrared signal to be detected through optical fiber transmission to the multi-channel grating; the coaxial cavity infrared signal detection system (2) carries out position adjustment through the multi-dimensional mobile platform (21) to detect infrared signals of each channel and each frequency band; the data acquisition and processing system carries out real-time data extraction and processing on the coaxial cavity infrared signal detection system (2);
the coaxial cavity infrared signal detection system comprises a coaxial resonant cavity (19), a multi-dimensional moving platform (21) and an infrared sensitizing material (20), wherein the coaxial resonant cavity (19) is fixed on the multi-dimensional moving platform (21) and has more than 6 available resonant frequencies, and a coaxial resonant cavity test hole (24) with the depth of 3.5mm is formed in the center of the top end of the coaxial resonant cavity and used for placing the infrared sensitizing material (20); the multi-dimensional mobile platform can be adjusted in four dimensions of up-down, left-right, front-back and angle; the infrared sensitizing material (20) adopts a glass fiber reinforced plastic plate or quartz as a matrix, and the bottom end of the matrix is coated with infrared sensitizing material coatings with different response characteristics under different infrared irradiation powers; microwave performance parameters of the coaxial resonant cavity at different positions are extracted, the dielectric constant and the loss tangent of the infrared sensitizing material are calculated according to the microwave resonance principle, and the frequency and the power of an infrared signal are detected.
2. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 1, wherein: the optical frequency division system (1) sequentially comprises an infrared filter (11), an impurity light eliminating diaphragm (12), an off-axis paraboloid large focusing mirror (13), a field diaphragm (14), an off-axis paraboloid small focusing mirror (15), a light chopper (16), optical fibers (17) and a multi-channel grating (18) along the infrared signal propagation direction, wherein the infrared filter (11) is tightly attached to the rear end of a sapphire window (9); the stray light eliminating diaphragm (12) is positioned between the infrared filter (11) and the off-axis paraboloid large focusing mirror (13); a field diaphragm (14) is arranged at the focus between the off-axis paraboloid large focusing mirror (13) and the off-axis paraboloid small focusing mirror (15); a chopper (16) is arranged between the off-axis paraboloid small focusing mirror (15) and the optical fiber (17); the multi-channel grating (18) is arranged at the rear end of the optical fiber (17); an infrared signal to be detected enters a vacuum low-temperature cabin through a sapphire window, enters an off-axis paraboloid large focusing mirror (13) through an infrared filter (11) and a stray light eliminating diaphragm (12), is subjected to total reflection transformation through the off-axis paraboloid large focusing mirror (13) and an off-axis paraboloid small focusing mirror (15), is transmitted to a multichannel grating (18) through an optical fiber (17) after being regulated and controlled through a chopper (16), and is subjected to channel division and direction division processing through the multichannel grating (18).
3. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 2, characterized in that: the off-axis paraboloid large focusing mirror (13) and the off-axis paraboloid small focusing mirror (15) adopt quartz as a substrate, and the surface of the substrate is plated with a gold or silver metal reflecting film and a dielectric protective film.
4. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 2, characterized in that: the multichannel grating (18) is made of sapphire, can perform multichannel frequency division processing on infrared signals of 2-6 mu m, and has different infrared wavelength ranges of each channel, and the resolution ratio of the multichannel grating is less than 200 nm.
5. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 1, wherein: the coaxial resonant cavity (19) is made of brass, the inner surface and the outer surface of the coaxial resonant cavity (19) are coated with silver and gold metal film layers in sequence, the working frequency range is 1-8GHz, and the quality factor is more than 1 ten thousand.
6. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 1, wherein: the data acquisition and processing system comprises a vector network analyzer (3) and a program control computer (4), wherein the vector network analyzer (3) is connected with a coaxial resonant cavity (19) through a microwave cable (8), the program control computer (4) controls the vector network analyzer (3) through a program to extract microwave performance parameters of the coaxial resonant cavity at different positions, and the dielectric constant and the loss tangent of the infrared sensitizing material are calculated according to the microwave resonance principle.
7. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 1, wherein: the inner surface of the vacuum low-temperature chamber is adhered with an infrared wave-absorbing material, and the working frequency range of the infrared wave-absorbing material covers near and middle infrared wave bands.
8. The weak infrared signal detection device based on the coaxial cavity microwave resonance principle of claim 1, wherein: the vacuum low-temperature cabin is characterized by further comprising a liquid nitrogen circulating refrigerating machine (6) and a vacuum pump (7) which are communicated to the inside of the vacuum low-temperature cabin (10) respectively, wherein the liquid nitrogen circulating refrigerating machine (6) is used for providing an ultralow-temperature environment for the inside of the vacuum low-temperature cabin (10), and the vacuum pump (7) adopts a molecular pump unit and can reduce the vacuum degree in the vacuum low-temperature cabin to 1 Pa.
9. The method for detecting the weak infrared signal based on the coaxial cavity microwave resonance principle by the device according to any one of claims 1 to 8 is characterized by comprising the following steps:
step 1: placing an optical frequency division system and a coaxial cavity infrared signal detection system in a vacuum low-temperature cabin, adjusting devices to ensure that an infrared signal detection circuit is smooth, connecting a program control computer and a vector network analyzer, connecting a coaxial resonant cavity and the vector network analyzer, connecting a liquid nitrogen circulating refrigerator and the vacuum low-temperature cabin, and connecting a vacuum pump and the vacuum low-temperature cabin;
step 2: starting a vacuumizing device, reducing the air pressure of the vacuum low-temperature cabin to be below 1Pa, and starting a liquid nitrogen circulating refrigerator to reduce the air pressure of the vacuum low-temperature cabin to-190 ℃;
and step 3: placing an infrared signal source in front of a sapphire window, enabling the infrared signal to enter a vacuum low-temperature cabin through the sapphire window, enabling the infrared signal to reach an off-axis paraboloid large focusing mirror after passing through an infrared filter and an impurity-removing light diaphragm, enabling the infrared signal to reach an off-axis paraboloid small focusing mirror through an off-axis paraboloid large focusing mirror and a field diaphragm to form a high-convergence collimated beam, then enabling the high-convergence collimated beam to be irradiated onto a multi-channel grating through an optical fiber after being regulated and controlled by a chopper, and finally enabling the infrared beam to be subjected to frequency division and channel division transmission through the multi-channel;
and 4, step 4: adjusting the multi-dimensional mobile platform to enable the coaxial resonant cavity to be positioned outside the multi-channel grating infrared signal transmission channel, testing the infrared sensitizing material positioned in the coaxial resonant cavity testing hole in the state by the aid of the process control computer and the vector network analyzer, and recording the dielectric constant of the infrared sensitizing material in the state as the dielectric constant of the infrared sensitizing material0Loss tangent is denoted tan0；
And 5: adjusting the multi-dimensional moving platform to enable the coaxial resonant cavity to be positioned on the multi-channel grating with the infrared wavelength of lambda1After the infrared sensitizing material is stabilized, the infrared sensitizing material in the state is tested by a process control computer and a vector network analyzer, and the dielectric constant of the infrared sensitizing material in the state is recorded as1Loss tangent is denoted tan1；
Step 6: calculating the change delta of the dielectric constant of the infrared sensitizing material before and after the irradiation of the opened infrared signal through the step 4 and the step 51Loss tangent change Δ tan1The calculation method is as follows:
Δ1＝1-0
Δtan1＝tan1-tan0
and 7: by changing the radiation power P of the infrared signal source, the infrared wavelength lambda under different radiation powers is obtained1Corresponding delta1And delta tan1Furthermore, the recorded data are counted and sorted to obtain the infrared wavelength lambda1Corresponding P-Delta1And P-delta tan1The data statistical table of (2);
and 8: adjusting the multi-dimensional moving platform to enable the coaxial resonant cavity to be positioned on the multi-channel grating with the infrared wavelength of lambda2After the channel direction is stabilized, repeating the step 5, the step 6 and the step 7 to obtain the infrared wavelength lambda2Corresponding P-Delta2And P-delta tan2The data statistical table of (2) is analogized in this way to obtain different infrared wavelengths as lambdanCorresponding P-DeltanAnd P-delta tannThe data statistical table of (2);
and step 9: detecting the infrared signal source to be detected with unknown radiation power, and calculating different infrared wavelengths lambda under the radiation powernDelta in the channel directionnAnd delta tannAnd the different infrared wavelengths obtained by step 8 are referred to as lambdanCorresponding P-DeltanAnd P-delta tannAnd the data statistics table obtains the radiation power P of the light source to be detected, and finally, the frequency and power detection of the infrared signal to be detected is realized.
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