A medium-long wave infrared spectral imaging data calibration device and method

Abstract

The application discloses a medium-long wave infrared spectrum imaging data calibration device and method, and relates to the technical field of spectrum testing. The device provided by the application comprises a black body, a cold screen, an infrared spectrum imaging equipment and a data processing unit; the black body is arranged at an entrance pupil of the infrared spectrum imaging equipment; the cold screen is movably arranged in the infrared spectrum imaging equipment, and when the cold screen is moved, the cold screen is arranged at the entrance pupil of the infrared spectrum imaging equipment; and the infrared spectrum imaging equipment is electrically connected with the data processing unit. In the process of calibrating the medium-long wave infrared spectrum imaging data, the data processing unit adopts complex Fourier transform, can convert frequency domain information into spatial domain information, improves the accuracy and reliability of data processing, and realizes accurate calibration of the infrared spectrum imaging data based on collected interference patterns and data radiation calibration results. In addition, the cold screen can effectively reduce the influence of air interference in the infrared spectrum imaging equipment, and improve the accuracy of the infrared spectrum imaging data.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spectral testing, in particular to a medium-long wave infrared spectral imaging data calibration device and method. BACKGROUND

[0002] The medium-long wave infrared spectral imaging technology has a wide application in the fields of military, security, environmental monitoring, etc. However, the existing medium-long wave infrared spectral imaging equipment is easily affected by the air interference in the instrument during the data radiation calibration, resulting in inaccurate imaging results.

[0003] To solve this problem, a medium-long wave infrared simultaneous spectral imaging system is proposed, which can obtain infrared images of multiple wave bands at the same time, and has important application value for target identification and component analysis. However, due to the influence of the detector response curve and the atmospheric environment, the radiation information in the original image has errors, which needs to be corrected through radiation calibration.

[0004] The existing calibration method generally adopts the general radiation calibration process of the infrared spectral imaging equipment, which measures the high and low temperature black body spectrum in turn, and obtains the response and bias coefficient of the instrument through formula (1):

[0005] (1)

[0006] In the formula, is the Fourier transform spectrum, which represents the electrical signal output by the detector. is the blackbody radiance; and are the response and bias coefficients of the radiation calibration, respectively.

[0007] Calibration is to obtain the response and bias coefficient of the system according to the standard source, and the electrical signal measured subsequently is converted into blackbody radiance through formula (2).

[0008] (2)

[0009] Based on the above description, the limitations of the existing calibration method are:

[0010] 1) During the process of measuring high and low temperature black body in turn, the state of the instrument inside changes, and the bias coefficient obtained by calibration is not a fixed value, and the calibration deviation is large;

[0011] 2) When used on the ground, there is air in the instrument, and the characteristics of CO2, water vapor, etc. in the air appear in the response and bias of the calibration coefficient, which interferes with the true spectrum. Even if the nitrogen filling method is used to reduce the air influence, after a long working time, the air interference characteristics will still appear in the calibration coefficient, which will interfere with the true spectrum. SUMMARY

[0012] To solve the above problems existing in the prior art, the present application provides a kind of long wave infrared spectral imaging data calibration device and method.

[0013] To achieve the above object, the present application provides the following scheme:

[0014] A kind of long wave infrared spectral imaging data calibration device, comprising: blackbody, cold screen, infrared spectral imaging equipment and data processing unit;

[0015] The blackbody is placed at the entrance pupil of the infrared spectral imaging equipment;The cold screen is movably arranged in the infrared spectral imaging equipment, and when the cold screen is moved, the cold screen is located at the entrance pupil of the infrared spectral imaging equipment;The infrared spectral imaging equipment is electrically connected with the data processing unit;

[0016] The infrared spectral imaging equipment is used to obtain first blackbody interferogram, second blackbody interferogram, cold screen interferogram and target interferogram;

[0017] The data processing unit is used to obtain data radiation calibration result based on the first blackbody interferogram, the second blackbody interferogram and the cold screen interferogram by using complex Fourier transform, and is used to complete the calibration processing of infrared spectral imaging data based on the target interferogram and the data radiation calibration result.

[0018] Optionally, the blackbody is an extended area source blackbody.

[0019] Optionally, the cold screen is arranged in the infrared spectral imaging equipment by mechanical moving parts.

[0020] Optionally, the first blackbody interferogram is the blackbody interferogram obtained at the first set temperature;The second blackbody interferogram is the blackbody interferogram obtained at the second set temperature.

[0021] Optionally, the first set temperature is a temperature higher than ambient temperature by 10 DEG C;The second set temperature is a temperature lower than ambient temperature by 10 DEG C.

[0022] The data processing unit comprises:

[0023] Radiation calibration module, electrically connected with the infrared spectral imaging equipment, for obtaining data radiation calibration result based on the first blackbody interferogram, the second blackbody interferogram and the cold screen interferogram;

[0024] Imaging processing module, electrically connected with the infrared spectral imaging equipment and the radiation calibration module respectively, for completing the calibration processing of infrared spectral imaging data based on the target interferogram and the data radiation calibration result.

[0025] Further, the application further provides a method for calibrating middle-long wave infrared spectral imaging data, which is applied to the device for calibrating middle-long wave infrared spectral imaging data provided above, and comprises the following steps:

[0026] obtaining a first blackbody interferogram, a second blackbody interferogram and a cold shield interferogram;

[0027] obtaining a first differential interferogram based on the first blackbody interferogram and the cold shield interferogram;

[0028] obtaining a second differential interferogram based on the second blackbody interferogram and the cold shield interferogram;

[0029] performing complex Fourier transform on the first differential interferogram to obtain a first complex spectrum;

[0030] performing complex Fourier transform on the second differential interferogram to obtain a second complex spectrum;

[0031] obtaining a response coefficient and a bias coefficient by using the first complex spectrum and the second complex spectrum;

[0032] completing data radiation calibration based on the response coefficient and the bias coefficient, and completing calibration processing of infrared spectral imaging data.

[0033] Optionally, completing data radiation calibration based on the response coefficient and the bias coefficient, and completing calibration processing of infrared spectral imaging data, specifically comprises:

[0034] obtaining a target interferogram;

[0035] performing complex Fourier transform on the target interferogram to obtain a complex spectrum;

[0036] determining the radiance of the target based on the complex spectrum, the response coefficient and the bias coefficient.

[0037] Optionally, the response coefficient is: ;

[0038] the bias coefficient is: ;

[0039] In the formula, R is the response coefficient, S1 is the first complex spectrum, S2 is the second complex spectrum, B1 is the blackbody radiance at the first set temperature, B2 is the blackbody radiance at the second set temperature, and B is the blackbody radiance at the third set temperature.

[0040] According to the specific embodiments of the application, the following technical effects are achieved:​​​​​​

[0041] The application can convert frequency domain information into spatial domain information by using complex Fourier transform during the long-wave infrared spectrum imaging data calibration process, and improve the accuracy and reliability of data processing. Moreover, the influence of air interference in the interior of the spectrum imaging device can be effectively reduced by setting a cold shield, and the accuracy of infrared spectrum imaging data is improved. The infrared spectrum imaging data is accurately calibrated by using a combination of radiation calibration and imaging processing modules. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0043] Figure 1 A structure diagram of the long-wave infrared spectrum imaging data calibration device provided by the present application is shown in the figure.

[0044] Figure 2 A flow chart of the long-wave infrared spectrum imaging data calibration method provided by the present application is shown in the figure.

[0045] Figure 3 A calibration process diagram provided by the present application is shown in the figure.

[0046] Symbol explanation:

[0047] 1-Black body, 2-Cold shield, 3-Infrared spectrum imaging device, 4-Data processing unit, 5-Interference light path, 6-Focal plane detector. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application.

[0049] The purpose of the present application is to provide a long-wave infrared spectrum imaging data calibration device and method, which can accurately calibrate long-wave infrared spectrum imaging data to avoid interference with the true spectrum.

[0050] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0051] The application provides a long-wave infrared spectral imaging data calibration device, which comprises a black body 1, a cold shield 2, an infrared spectral imaging device 3 and a data processing unit 4.

[0052] The black body 1 is arranged at the entrance pupil of the infrared spectral imaging device 3. The cold shield 2 is movably arranged in the infrared spectral imaging device 3, and when the cold shield 2 is moved, the cold shield 2 is located at the entrance pupil of the infrared spectral imaging device 3. The infrared spectral imaging device 3 is electrically connected with the data processing unit 4. The temperature of the cold shield can be determined according to actual requirements, for example, is not lower than -80 DEG C.

[0053] The infrared spectral imaging device 3 is used for acquiring a first black body interference graph, a second black body interference graph, a cold shield interference graph and a target interference graph.

[0054] The data processing unit 4 is used for obtaining a data radiation calibration result based on the first black body interference graph, the second black body interference graph and the cold shield interference graph by using complex Fourier transform, and is used for completing the calibration of the infrared spectral imaging data based on the target interference graph and the data radiation calibration result.

[0055] The data processing unit 4 performs complex Fourier transform on the collected spectral imaging data, can analyze external radiation and internal interference from the complex spectrum, performs data radiation calibration according to the data after the complex Fourier transform and the radiation characteristics of the known reference object, and further processes the data after the radiation calibration to generate accurate and reliable infrared spectral imaging results.

[0056] In actual application, the black body 1 preferably adopts an extended surface source black body.

[0057] In addition, one cold shield 2 is arranged in the infrared spectral imaging device 3, which is used for reducing the influence of internal radiation and internal air interference of the infrared spectral imaging device 3 and can accurately measure the internal radiation and internal air absorption of the infrared spectral imaging device 3.

[0058] In actual application, the cold shield 2 is arranged in the infrared spectral imaging device 3 through a mechanical moving part. The mechanical moving part is a structure such as a lotus leaf, an extension rod, a rotating shaft and the like which can enable the cold shield 2 to be located at the entrance pupil of the infrared spectral imaging device 3.

[0059] Further, in actual application, the first black body interference graph is a black body interference graph acquired at a first set temperature (for example, a temperature higher than the ambient temperature by 10 DEG C). The second black body interference graph is a black body interference graph acquired at a second set temperature (for example, a temperature lower than the ambient temperature by 10 DEG C).

[0060] Furthermore, to generate accurate and reliable infrared spectral imaging results, the data processing unit 4 used in this invention can be configured to include a radiometric calibration module and an imaging processing module. The radiometric calibration module is electrically connected to the infrared spectral imaging device 3 and is mainly used to obtain data radiometric calibration results based on the first blackbody interferogram, the second blackbody interferogram, and the cold screen interferogram. The imaging processing module is electrically connected to both the infrared spectral imaging device 3 and the radiometric calibration module, and is mainly used to complete the calibration processing of the infrared spectral imaging data based on the target interferogram and the data radiometric calibration results.

[0061] In this process, radiometric calibration is performed on the data obtained from the complex Fourier transform and the known radiation characteristics of a reference object. The radiometrically calibrated data is then further processed to generate accurate and reliable infrared spectral imaging results.

[0062] Furthermore, the present invention also provides a method for calibrating mid-to-long-wave infrared spectral imaging data, which is applied to the aforementioned mid-to-long-wave infrared spectral imaging data calibration device. For example... Figure 2 As shown, the method includes:

[0063] Step 100: Obtain the first blackbody interferogram, the second blackbody interferogram, and the cold screen interferogram.

[0064] Step 101: Obtain the first differential interferogram based on the first blackbody interferogram and the cold screen interferogram.

[0065] Step 102: Obtain the second differential interferogram based on the second blackbody interferogram and the cold screen interferogram.

[0066] Step 103: Perform a complex Fourier transform on the first difference interferogram to obtain the first complex spectrum.

[0067] Step 104: Perform a complex Fourier transform on the second difference interferogram to obtain the second complex spectrum.

[0068] Step 105: Obtain the response coefficient and bias coefficient using the first and second complex spectra. The formula for determining the response coefficient is:

[0069] (3)

[0070] The formula for determining the bias coefficient is:

[0071] (4)

[0072] In the formula, For the response coefficient, For the first complex spectrum, For the second complex spectrum, The blackbody radiance at the first set temperature, is the blackbody radiance at the second set temperature, is the response coefficient.

[0073] Step 106: completing data radiometric calibration based on the response coefficient and the bias coefficient, completing the calibration processing of the infrared spectral imaging data. The specific implementation process of this step includes:

[0074] Step 1061: obtaining the target interferogram.

[0075] Step 1062: performing complex Fourier transform on the target interferogram to obtain complex spectrum.

[0076] Step 1063: determining the radiance of the target based on the complex spectrum, the response coefficient and the bias coefficient.

[0077] A specific application example is provided below to illustrate the specific implementation process of the above-mentioned scheme of the present application. In this embodiment, the infrared spectral imaging device is a spectrometer, and the structure thereof is shown in FIG. 1. The calibration process in this embodiment is shown in FIG. 2, and specifically includes: Figure 1 Figure 3

[0078] Step 1: the blackbody 1 is located at the entrance pupil of the spectrometer 3, and two temperatures of high temperature and low temperature are set. The high temperature is 10℃ higher than the ambient temperature, and the low temperature is 10℃ lower than the ambient temperature.

[0079] Step 2: the cold shield 2 is located inside the spectrometer, and when the cold shield 2 needs to be measured, the cold shield 2 is moved to the entrance pupil of the field of view by mechanical components. When it is not needed to be measured, the cold shield 2 is moved away so as to be located outside the entrance pupil of the field of view. The temperature of the built-in cold shield 2 is set to -80℃.

[0080] The interference light path 5 of the spectrometer 3 performs light splitting on the entering light to obtain interferogram data.

[0081] After the light at the entrance pupil is split by the interference light path 5, it enters the focal plane detector 6, and each pixel of the focal plane obtains interferogram data to form an interferogram data array.

[0082] The interferogram data of each pixel is input to the data processing unit 4, and the data processing unit 4 performs complex FFT transform on the interferogram. By measuring the high-temperature blackbody, the low-temperature blackbody and the cold shield data, the response coefficient and the bias coefficient are calibrated.

[0083] Specifically, the specific implementation process of the above-mentioned data processing is as follows:

[0084] 1) measuring the high-temperature external blackbody interferogram (i.e. the first blackbody interferogram) Then, the cold shield 2 is switched to the field of view, and the cold shield interferogram is measured ​​After the measurement, the cold shield 2 is removed. Then the cold shield 2 is switched into the field of view, and the cold shield interferogram is measured After the measurement, the cold shield 2 is removed.

[0085] 2) The high and low temperature blackbody interferograms are subtracted respectively from the measured high and low temperature blackbody interferograms, to obtain two differential interferograms (i.e. the first and second interferograms):

[0086] (5)

[0087] In the formula, is the first interferogram, is the second interferogram.

[0088] 3) According to formula (6), complex FFT transformation is performed on the two differential interferograms respectively, to obtain complex spectra.

[0089] (6)

[0090] (7)

[0091] In the formula, v represents the wave number, is the complex spectrum after complex FFT transformation, is the differential interferogram, is the second interferogram, is the first interferogram, is the complex spectrum after complex FFT transformation on the second differential interferogram, i.e. the second complex spectrum, is the complex spectrum after complex FFT transformation on the first differential interferogram, i.e. the first complex spectrum.

[0092] 4) In the calibration process, the obtained complex spectra are used to obtain the response coefficient and the bias coefficient of the spectrometer according to the relationship between the spectral voltage value and the blackbody theoretical radiance (i.e. formula (8)). The determination formulas of the response coefficient and the bias coefficient are shown in formula (3) and formula (4).

[0093] (8)

[0094] In the formula, is the Fourier transformed spectrum. is the blackbody radiance. and are the response coefficient and the bias coefficient respectively.

[0095] Through complex calibration, the influence of internal radiation of the instrument on calibration is eliminated.

[0096] 5), the measured external target spectrum The measurement and calculation are as follows:

[0097] The interferogram is measured towards the external target And the complex spectrum is obtained by Fourier transform , which is:

[0098] (9)

[0099] In the formula, and are the real part and the imaginary part of the complex spectrum , respectively, is the imaginary unit.

[0100] Further, the radiance is obtained based on the obtained complex spectrum and the response coefficient and the bias coefficient after radiation calibration, which is:

[0101] (10)

[0102] In the formula, is the obtained radiance, is the response coefficient after radiation calibration, is the bias coefficient after radiation calibration.

[0103] Based on the above description, the present application has the following advantages over the prior art:

[0104] 1. The present application uses complex Fourier transform technology, which can convert frequency domain information into spatial domain information, improving the accuracy and reliability of data processing.

[0105] 2. The present application introduces built-in cold screen technology, which effectively reduces the influence of internal air interference on the instrument and improves the accuracy of infrared spectral imaging data.

[0106] 3. The present application combines a radiation calibration module and an imaging processing module to achieve accurate calibration of infrared spectral imaging data.

[0107] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between each embodiment can be referred to each other.

[0108] The principles and implementation methods of the present application are described by applying specific examples in this paper. The above description of the embodiments is only to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation method and application range will be changed. In summary, the content of this specification should not be understood as a limitation of the present application.

Claims

1. A device for calibrating mid-long wave infrared spectral imaging data, characterized in that, The method is applied to the long-wave infrared spectral imaging data calibration device as claimed in any one of claims 1-6, and the method comprises: a blackbody, a cold shield, an infrared spectral imaging device, and a data processing unit; the blackbody is arranged at an entrance pupil of the infrared spectral imaging device; the cold shield is movably arranged in the infrared spectral imaging device, and when the cold shield is moved, the cold shield is located at the entrance pupil of the infrared spectral imaging device; the infrared spectral imaging device is electrically connected to the data processing unit; the infrared spectral imaging device is configured to acquire a first blackbody interferogram, a second blackbody interferogram, and a cold shield interferogram; the data processing unit is configured to obtain data radiation calibration results based on the first blackbody interferogram, the second blackbody interferogram, and the cold shield interferogram by using complex Fourier transform, and to complete calibration processing of infrared spectral imaging data based on a target interferogram and the data radiation calibration results.

2. The mid-long wave infrared spectral imaging data calibration apparatus according to claim 1, characterized in that, The blackbody is an extended surface source blackbody.

3. The medium-long wave infrared spectral imaging data calibration apparatus according to claim 1, characterized in that, The cold shield is movably arranged in the infrared spectral imaging device by a mechanical moving component.

4. The medium-long wave infrared spectral imaging data calibration apparatus according to claim 1, characterized in that, The first blackbody interferogram is an interferogram acquired at a first set temperature; and the second blackbody interferogram is an interferogram acquired at a second set temperature.

5. The medium-long wave infrared spectral imaging data calibration apparatus according to claim 4, characterized in that, The first set temperature is a temperature 10°C higher than an ambient temperature; and the second set temperature is a temperature 10°C lower than the ambient temperature.

6. The medium-long wave infrared spectral imaging data calibration apparatus according to claim 1, wherein, The data processing unit comprises: a radiation calibration module electrically connected to the infrared spectral imaging device, configured to obtain data radiation calibration results based on the first blackbody interferogram, the second blackbody interferogram, and the cold shield interferogram; an imaging processing module electrically connected to the infrared spectral imaging device and the radiation calibration module, configured to complete calibration processing of infrared spectral imaging data based on the target interferogram and the data radiation calibration results.

7. A calibration method for mid- and long-wave infrared spectral imaging data, characterized in that, The method is applied to the long-wave infrared spectral imaging data calibration device as claimed in any one of claims 1-6, and the method comprises: acquiring a first blackbody interferogram, a second blackbody interferogram, and a cold shield interferogram; obtaining a first differential interferogram based on the first blackbody interferogram and the cold shield interferogram; obtaining a second differential interferogram based on the second blackbody interferogram and the cold shield interferogram; performing complex Fourier transform on the first differential interferogram to obtain a first complex spectrum; performing complex Fourier transform on the second differential interferogram to obtain a second complex spectrum; obtaining a response coefficient and a bias coefficient by using the first complex spectrum and the second complex spectrum; completing data radiation calibration based on the response coefficient and the bias coefficient, and completing calibration processing of infrared spectral imaging data.

8. The mid-long wave infrared spectral imaging data calibration method of claim 7, wherein, The method for completing data radiation calibration based on the response coefficient and the bias coefficient, and completing calibration processing of infrared spectral imaging data specifically comprises: acquiring a target interferogram; performing complex Fourier transform on the target interferogram to obtain a complex spectrum; determining a target radiance based on the complex spectrum, the response coefficient, and the bias coefficient.

9. The mid-long wave infrared spectral imaging data calibration method of claim 7, wherein, The response coefficient is: The biasing coefficient is: wherein is a response coefficient, is a first complex spectrum, is a second complex spectrum, L theory (v) bb,high is a blackbody radiance at a first set temperature, L theory (v) bb,low is a blackbody radiance at a second set temperature, is a response coefficient.

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