Detector output voltage nonlinearity testing method

Abstract

The invention relates to the technical field of infrared focal plane detection, in particular to a detector output voltage nonlinearity test method, which comprises the following steps of: setting a detector to image a preset black body; respectively acquiring an output voltage value and an area array output voltage mean value of each pixel of the detector under the first preset effective integration time and the second preset effective integration time, and calculating a first correction coefficient and a second correction coefficient of each pixel through a two-point correction formula; obtaining an output voltage value of each pixel of the detector in a third preset effective integration time, and calculating a correction voltage value of each pixel and an area array correction voltage mean value; performing plane fitting according to the correction voltage values of all the pixels of the detector, calculating the residual root mean square of the correction voltage values of all the pixels of the detector and the corresponding fitting voltage values in the fitting plane, and calculating the nonlinearity of the area array voltage value curved surface; therefore, the overall nonlinearity condition of the area array can be intuitively evaluated.

Description

Technical Field

[0001] This invention relates to the field of infrared focal plane array detection technology, and in particular to a method for testing the nonlinearity of detector output voltage. Background Technology

[0002] The nonlinearity readout of the detector is an important factor affecting the imaging quality of infrared focal plane arrays. Existing nonlinearity testing methods usually adopt single-point calibration or multi-point piecewise fitting, and evaluate its linearity by measuring the voltage response curve of each pixel under different irradiance. However, this method can only obtain nonlinearity data of discrete pixels or local sampling areas, and cannot intuitively show the spatial distribution characteristics of the nonlinearity of the entire focal plane array. It is difficult to comprehensively evaluate the overall nonlinearity level of the array, and has the limitations of unintuitive test results and lack of global evaluation capability. Summary of the Invention

[0003] The purpose of this invention is to provide a method for testing the nonlinearity of detector output voltage, which can solve the problem that existing nonlinearity testing methods cannot evaluate the overall nonlinearity of the array.

[0004] To address the aforementioned technical problems, this invention provides a method for testing the nonlinearity of detector output voltage. The method includes: placing the detector in front of a blackbody, setting the operating temperature of the blackbody to a preset temperature, and setting the distance between the detector and the blackbody to be less than or equal to a preset distance; acquiring the output voltage value of each pixel of the detector at a first preset effective integration time and a second preset effective integration time, as well as the average output voltage of the detector array at the first and second preset effective integration times; for each pixel of the detector, based on the output voltage value of that pixel at the first and second preset effective integration times and the average output voltage of the detector array at the first and second preset effective integration times, and using a two-point correction formula to calculate... Calculate the first and second correction coefficients for the pixel; obtain the output voltage value of each pixel of the detector at a third preset effective integration time, and for each pixel, correct the output voltage value of the pixel at the third preset effective integration time according to the first and second correction coefficients to obtain the corrected voltage value of the pixel, and obtain the average correction voltage value of the detector array according to the average correction voltage value of all pixels of the detector; perform plane fitting according to the correction voltage values ​​of all pixels of the detector, and obtain the fitted voltage value corresponding to each pixel of the detector according to the plane fitting result; calculate the root mean square of the residuals according to the correction voltage values ​​and the fitted voltage values ​​of all pixels of the detector, and obtain the output voltage nonlinearity value of the detector according to the ratio of the root mean square of the residuals to the average correction voltage value of the detector array.

[0005] Optionally, acquiring the output voltage value of each pixel of the detector at a first preset effective integration time and a second preset effective integration time, and the average array output voltage value of the detector at the first preset effective integration time and the second preset effective integration time, includes: controlling the detector to continuously acquire multiple frames of first detection data with an integration time of the first preset integration time under optimal bias voltage conditions, so as to obtain multiple first output voltage values ​​corresponding to each pixel of the detector; controlling the detector to continuously acquire multiple frames of second detection data with an integration time of the second preset integration time under optimal bias voltage conditions, so as to obtain multiple second output voltage values ​​corresponding to each pixel of the detector. Voltage values; for each pixel of the detector, the output voltage value of the pixel under the first preset effective integration time is obtained based on the average of the multiple first output voltage values ​​corresponding to the pixel, and the output voltage value of the pixel under the second preset effective integration time is obtained based on the average of the multiple second output voltage values ​​corresponding to the pixel; the average array output voltage of the detector under the first preset effective integration time is obtained based on the average of the output voltage values ​​of all pixels of the detector under the first preset effective integration time; the average array output voltage of the detector under the second preset effective integration time is obtained based on the average of the output voltage values ​​of all pixels of the detector under the second preset effective integration time.

[0006] Optionally, obtaining the output voltage value of each pixel of the detector at a third preset effective integration time includes: controlling the detector to continuously acquire multiple frames of third detection data with an integration time of the third preset integration time under optimal bias voltage conditions, so as to obtain multiple third output voltage values ​​corresponding to each pixel of the detector; and obtaining the output voltage value of each pixel at the third preset effective integration time based on the average of the multiple third output voltage values ​​corresponding to the pixel for each pixel.

[0007] Optionally, the third preset effective integration time is greater than the second preset effective integration time, and the second preset effective integration time is greater than the first preset effective integration time.

[0008] Optionally, the first preset effective integration time, the second preset effective integration time, and the third preset effective integration time are set according to the output voltage swing of the detector and the average value of the array bare voltage obtained by pre-calibration.

[0009] Optionally, the output voltage swing and the average bare voltage of the detector array are calibrated through the following process: placing the detector in front of a blackbody, setting the operating temperature of the blackbody to the preset temperature, and setting the distance between the detector and the blackbody to be less than or equal to the preset distance; controlling the detector to continuously acquire multiple frames of fourth detection data with an integration time equal to the minimum integration time under minimum bias voltage conditions, so as to obtain multiple fourth output voltage values ​​corresponding to each pixel of the detector; adjusting the integration time under optimal bias voltage conditions until the detector array reaches saturation, so as to obtain the saturation integration time corresponding to the detector; controlling the detector to continuously acquire multiple frames with an integration time equal to the saturation integration time under optimal bias voltage conditions. The fifth detection data of time is used to obtain multiple fifth output voltage values ​​corresponding to each pixel of the detector; for each pixel of the detector, the minimum output voltage value corresponding to the pixel is obtained based on the average of the multiple fourth output voltage values ​​corresponding to the pixel, and the maximum output voltage value corresponding to the pixel is obtained based on the average of the multiple fifth output voltage values ​​corresponding to the pixel; the average bare voltage of the detector array is obtained based on the average of the minimum output voltage values ​​corresponding to all pixels of the detector, and the average saturation voltage of the detector array is obtained based on the average of the maximum output voltage values ​​corresponding to all pixels of the detector; the output voltage swing of the detector is obtained based on the difference between the average saturation voltage of the detector array and the average bare voltage of the detector array.

[0010] Optionally, the first correction coefficient and the second correction coefficient for each pixel can be calculated using the following two-point correction formula:

[0011]

[0012] In the formula, i∈[1,2,3,…,M], M is the total number of rows in the detector's array, j∈[1,2,3,…,N], N is the total number of columns in the detector's array. The average output voltage of the detector array during the first preset effective integration time is denoted as . Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the first preset effective integration time. The average output voltage of the detector array during the second preset effective integration time is given. Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the second preset effective integration time. Let be the first correction coefficient for the pixel in the i-th row and j-th column of the detector's array. It is the second correction coefficient for the pixel in the i-th row and j-th column of the detector's array.

[0013] Optionally, the correction voltage value for each pixel can be calculated using the following formula:

[0014]

[0015] In the formula, Let be the correction voltage value of the pixel in the i-th row and j-th column of the detector array during the third preset effective integration time. Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the third preset effective integration time.

[0016] Optionally, before performing planar fitting based on the correction voltage values ​​of all pixels of the detector, the method further includes: for each pixel of the detector, if the difference between the correction voltage value of the pixel and the average of the correction voltage values ​​of its multiple neighboring pixels is within a preset range, then the pixel is determined to be a normal pixel; otherwise, the pixel is determined to be a bad pixel; for each bad pixel in the detector, the average of the correction voltage values ​​of the normal pixels in the multiple neighboring pixels surrounding the bad pixel is used as the new correction voltage value of the bad pixel.

[0017] Optionally, the step of performing plane fitting based on the correction voltage values ​​of all pixels of the detector includes: performing plane fitting on the correction voltage values ​​of all pixels of the detector based on the least squares method.

[0018] Compared with existing technologies, the detector output voltage nonlinearity testing method provided by this invention has the following advantages:

[0019] The detector output voltage nonlinearity testing method provided by this invention includes placing the detector in front of a blackbody, setting the operating temperature of the blackbody to a preset temperature, and setting the distance between the detector and the blackbody to be less than or equal to a preset distance; acquiring the output voltage value of each pixel of the detector at a first preset effective integration time and a second preset effective integration time, as well as the average output voltage of the detector array at the first preset effective integration time and the second preset effective integration time; for each pixel of the detector, calculating the first effective voltage of the pixel at the first preset effective integration time and the second preset effective integration time, and the average output voltage of the detector array at the first preset effective integration time and the second preset effective integration time, using a two-point correction formula. The system employs a correction coefficient and a second correction coefficient; it obtains the output voltage value of each pixel of the detector at a third preset effective integration time, and for each pixel, corrects the output voltage value of the pixel at the third preset effective integration time according to the first correction coefficient and the second correction coefficient of that pixel to obtain the corrected voltage value of that pixel, and obtains the average corrected voltage value of the detector array according to the average value of the corrected voltage values ​​of all pixels of the detector; it performs plane fitting based on the corrected voltage values ​​of all pixels of the detector, and obtains the fitted voltage value corresponding to each pixel of the detector according to the plane fitting result; it calculates the root mean square of the residuals based on the corrected voltage values ​​and the fitted voltage values ​​of all pixels of the detector, and obtains the output voltage nonlinearity value of the detector according to the ratio of the root mean square of the residuals to the average corrected voltage value of the detector array.

[0020] Therefore, the detector output voltage nonlinearity test method provided by the present invention obtains different output voltage values ​​of the detector pixels by changing the integration time. Based on the elimination of the influence of pixel non-uniformity by two-point correction, plane fitting is performed, and the nonlinearity is quantified by the ratio of the root mean square of the residual to the mean value of the area array correction voltage. This allows for an intuitive evaluation of the overall nonlinearity of the detector area array. Attached Figure Description

[0021] Figure 1 A flowchart of a detector output voltage nonlinearity testing method provided in one embodiment of the present invention.

[0022] Figure 2 A comparison diagram of the surface voltage value curve and the fitting plane in the detector output voltage nonlinearity test method provided in one embodiment of the present invention.

[0023] Figure 3 This is a report on the surface nonlinearity analysis in the detector output voltage nonlinearity testing method provided in one embodiment of the present invention. Detailed Implementation

[0024] The detector output voltage nonlinearity testing method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. Please refer to the accompanying drawings for the objectives, features, and advantages of this invention to make them more apparent and understandable.

[0025] The core idea of ​​this invention is to provide a method for testing the nonlinearity of detector output voltage, which can solve the problem that existing nonlinearity testing methods cannot evaluate the overall nonlinearity of the array.

[0026] To achieve the above-mentioned goals, this invention provides a method for testing the nonlinearity of detector output voltage. Please refer to [the relevant documentation]. Figure 1 ,like Figure 1 As shown, the detector output voltage nonlinearity testing method provided by the present invention includes: step S100, placing the detector in front of a blackbody, setting the operating temperature of the blackbody to a preset temperature, and setting the distance between the detector and the blackbody to be less than or equal to a preset distance; step S200, acquiring the output voltage value of each pixel of the detector at a first preset effective integration time and a second preset effective integration time, and the average output voltage of the detector array at the first preset effective integration time and the second preset effective integration time; step S300, for each pixel of the detector, calculating the nonlinearity of the pixel using a two-point correction formula based on the output voltage value of the pixel at the first preset effective integration time and the second preset effective integration time, and the average output voltage of the detector array at the first preset effective integration time and the second preset effective integration time. First correction coefficient and second correction coefficient; Step S400: Obtain the output voltage value of each pixel of the detector under the third preset effective integration time, and for each pixel, correct the output voltage value of the pixel under the third preset effective integration time according to the first correction coefficient and the second correction coefficient of the pixel to obtain the corrected voltage value of the pixel, and obtain the average correction voltage value of the detector array according to the average value of the correction voltage values ​​of all pixels of the detector; Step S500: Perform plane fitting according to the correction voltage values ​​of all pixels of the detector, and obtain the fitted voltage value corresponding to each pixel of the detector according to the plane fitting result; Step S600: Calculate the root mean square of the residuals according to the correction voltage values ​​and the fitted voltage values ​​of all pixels of the detector, and obtain the output voltage nonlinearity value of the detector according to the ratio of the root mean square of the residuals and the average correction voltage value of the detector array.

[0027] Therefore, the detector output voltage nonlinearity test method provided by the present invention obtains different output voltage values ​​of the detector pixels by changing the integration time. Based on the elimination of the influence of pixel non-uniformity by two-point correction, plane fitting is performed, and the nonlinearity is quantified by the ratio of the root mean square of the residual to the mean value of the area array correction voltage. This allows for an intuitive evaluation of the overall nonlinearity of the detector area array.

[0028] Furthermore, step S100 includes: first preparing the detector, setting the array size to be... The detector is placed in front of the blackbody, the operating temperature of the blackbody is set to 20℃, and the distance between the detector window and the radiation surface of the blackbody is less than or equal to 1cm. The detector is then connected to the test system and powered on to make it work normally.

[0029] Furthermore, the step of acquiring the output voltage value of each pixel of the detector at a first preset effective integration time and a second preset effective integration time, as well as the average array output voltage value of the detector at the first preset effective integration time and the second preset effective integration time, includes: controlling the detector to continuously acquire multiple frames of first detection data with an integration time of the first preset integration time under optimal bias voltage conditions, so as to obtain multiple first output voltage values ​​corresponding to each pixel of the detector; controlling the detector to continuously acquire multiple frames of second detection data with an integration time of the second preset integration time under optimal bias voltage conditions, so as to obtain multiple second output voltage values ​​corresponding to each pixel of the detector. Output voltage value; for each pixel of the detector, the output voltage value of the pixel under the first preset effective integration time is obtained based on the average of the multiple first output voltage values ​​corresponding to the pixel, and the output voltage value of the pixel under the second preset effective integration time is obtained based on the average of the multiple second output voltage values ​​corresponding to the pixel; the average array output voltage of the detector under the first preset effective integration time is obtained based on the average of the output voltage values ​​of all pixels of the detector under the first preset effective integration time; the average array output voltage of the detector under the second preset effective integration time is obtained based on the average of the output voltage values ​​of all pixels of the detector under the second preset effective integration time.

[0030] Therefore, by acquiring multiple frames and averaging the output voltage value of each pixel and the average voltage value of the entire array, random noise can be effectively suppressed, thereby significantly improving the signal-to-noise ratio and stability of the output voltage value of each pixel under the first preset effective integration time and the second preset effective integration time.

[0031] Furthermore, the detector is set to the optimal Gpol (bias voltage), which is determined through pre-testing. That is, the fixed bias voltage range with the widest linear response range and the highest signal-to-noise ratio is selected while ensuring that the detector output does not saturate. Then, the first preset effective integration time is set. Second preset effective integration time This allows the array to achieve different well depths, the well depth of which is calculated using the following formula:

[0032] Well depth =

[0033] First preset effective integration time / Second preset effective integration time To reduce the impact of noise on the results, multiple frames (e.g., 100 frames) of data are continuously acquired. For each pixel, data is integrated within the first preset effective integration time. / Second preset effective integration time The average of multiple (e.g., 100) output voltage values ​​is obtained during the first preset effective integration time. / Second preset effective integration time Output voltage value / Then, based on the first preset effective integration time The average output voltage of all pixels under the given conditions can be used to calculate the first preset effective integration time. Average output voltage of the array below Similarly, according to the second preset effective integration time... The average output voltage of all pixels under the given conditions can be used to calculate the value of the second preset effective integration time. Average output voltage of the array below .

[0034] Furthermore, the step of obtaining the output voltage value of each pixel of the detector under the third preset effective integration time includes: controlling the detector to continuously collect multiple frames of third detection data with an integration time of the third preset integration time under the optimal bias voltage condition, so as to obtain multiple third output voltage values ​​corresponding to each pixel of the detector.

[0035] For each pixel of the detector, the output voltage value of the pixel at the third preset effective integration time is obtained based on the average of the multiple third output voltage values ​​corresponding to the pixel.

[0036] Therefore, by acquiring multiple frames under the optimal bias voltage condition and taking the average of multiple third output voltage values ​​corresponding to each pixel, random noise and instantaneous disturbances can be effectively filtered out, thereby significantly improving the signal-to-noise ratio and measurement stability of the output voltage of each pixel under the third preset effective integration time.

[0037] Furthermore, the third preset effective integration time is greater than the second preset effective integration time, and the second preset effective integration time is greater than the first preset effective integration time.

[0038] Therefore, by setting a third preset effective integration time that is greater than the first and second preset effective integration times, the detector can operate in a high signal response region that is closer to saturation, thereby effectively stimulating its potential nonlinear response characteristics.

[0039] Furthermore, the first preset effective integration time, the second preset effective integration time, and the third preset effective integration time are set according to the output voltage swing of the detector and the average value of the array bare voltage obtained by pre-calibration.

[0040] Therefore, the output voltage of the detector at each preset effective integration time can be accurately distributed in different characteristic segments of the linear response region, which can make full use of the effective dynamic range of the detector, effectively avoid the risk of signal saturation or cutoff, and ensure that the output voltage values ​​corresponding to the three preset integration times have appropriate gradient differences and signal-to-noise ratios.

[0041] Furthermore, the output voltage swing and the average bare voltage of the detector array are calibrated through the following process: The detector is placed in front of a blackbody, and the operating temperature of the blackbody is set to the preset temperature, and the distance between the detector and the blackbody is set to be less than or equal to the preset distance; the detector is controlled to continuously acquire multiple frames of fourth detection data with an integration time equal to the minimum integration time under minimum bias voltage conditions, so as to obtain multiple fourth output voltage values ​​corresponding to each pixel of the detector; under optimal bias voltage conditions, the integration time is adjusted until the detector array reaches saturation, so as to obtain the saturation integration time corresponding to the detector; the detector is controlled to continuously acquire multiple frames of integration time equal to the minimum integration time under optimal bias voltage conditions. The fifth detection data is divided into time intervals to obtain multiple fifth output voltage values ​​corresponding to each pixel of the detector. For each pixel of the detector, the minimum output voltage value corresponding to the pixel is obtained based on the average of the multiple fourth output voltage values ​​corresponding to the pixel, and the maximum output voltage value corresponding to the pixel is obtained based on the average of the multiple fifth output voltage values ​​corresponding to the pixel. The average bare voltage of the detector array is obtained based on the average of the minimum output voltage values ​​corresponding to all pixels of the detector, and the average saturation voltage of the detector array is obtained based on the average of the maximum output voltage values ​​corresponding to all pixels of the detector. The output voltage swing of the detector is obtained based on the difference between the average saturation voltage of the detector array and the average bare voltage of the detector array.

[0042] Therefore, by calculating the output voltage swing of the detector, the dynamic operating range and response sensitivity of the detector can be fully characterized. It can also provide benchmark parameters for subsequent non-uniformity correction, defective element identification and nonlinearity analysis, and ensure the standardization of the test process.

[0043] Specifically, set the minimum Gpol and the minimum integration time. To reduce the impact of noise on the results, multiple frames (e.g., 100 frames) of data are continuously acquired, and the minimum output voltage value corresponding to that pixel is obtained by averaging multiple (e.g., 100) fourth output voltage values ​​for each pixel. Where i and j represent the number of rows and columns of the array, respectively, and the average bare voltage of the array is . Set the optimal Gpol and adjust the integration time. To saturate the array, continuously acquire multiple frames (e.g., 100 frames) of data, and average the multiple (e.g., 100) fifth output voltage values ​​for each pixel to obtain the maximum output voltage value corresponding to that pixel. The average voltage of the array at this time This is the average saturation voltage of the array. The output voltage swing of the detector is then calculated using the following formula:

[0044]

[0045] In the formula, This refers to the output voltage swing of the detector. The average saturation voltage of the array is given. This represents the average bare voltage of the array.

[0046] Furthermore, the first correction coefficient and the second correction coefficient for each pixel are calculated using the following two correction formulas:

[0047]

[0048] In the formula, i∈[1,2,3,…,M], M is the total number of rows in the detector's array, j∈[1,2,3,…,N], N is the total number of columns in the detector's array. The average output voltage of the detector array during the first preset effective integration time is denoted as . Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the first preset effective integration time. The average output voltage of the detector array during the second preset effective integration time is given. Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the second preset effective integration time. Let be the first correction coefficient for the pixel in the i-th row and j-th column of the detector's array. It is the second correction coefficient for the pixel in the i-th row and j-th column of the detector's array.

[0049] Therefore, by calculating the first correction coefficient, the difference in response slope between pixels can be effectively corrected. At the same time, by calculating the second correction coefficient, the inconsistency of dark level can be eliminated, which can provide a reliable correction benchmark for subsequent nonlinearity calculation, and enable nonlinear evaluation to remove non-uniformity interference.

[0050] Furthermore, the correction voltage value for each pixel is calculated using the following formula:

[0051]

[0052] In the formula, Let be the correction voltage value of the pixel in the i-th row and j-th column of the detector array during the third preset effective integration time. Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the third preset effective integration time.

[0053] This ensures that the response characteristics of each pixel are independently corrected, eliminating spatial fixed-mode noise caused by differences in the slope of the bias voltage between pixels and the dark level offset, thus providing a basis for the subsequent accurate construction of the array voltage value surface and the calculation of its nonlinearity.

[0054] Furthermore, before performing planar fitting based on the correction voltage values ​​of all pixels of the detector, the method further includes: for each pixel of the detector, if the difference between the correction voltage value of the pixel and the average of the correction voltage values ​​of its multiple neighboring pixels is within a preset range, then the pixel is determined to be a normal pixel; otherwise, the pixel is determined to be a bad pixel; for each bad pixel in the detector, the average of the correction voltage values ​​of the normal pixels in the multiple neighboring pixels surrounding the bad pixel is used as the new correction voltage value of the bad pixel.

[0055] Therefore, the interference of extreme outliers on nonlinearity evaluation can be effectively avoided.

[0056] Furthermore, the preset range can be set according to the output voltage swing of the detector. For example, the preset range can be set to (-5mV, 5mV). In this case, for each pixel, if the absolute value of the difference between the correction voltage value of the pixel and the average value of the correction voltage values ​​of the eight neighboring pixels in the surrounding 3*3 area is greater than or equal to 5mV, then the pixel is determined to be a bad pixel. For the bad pixel, the average value of the correction voltage values ​​of all normal pixels in the surrounding eight neighboring areas is used as the final correction voltage value of the bad pixel.

[0057] Furthermore, the step of performing plane fitting based on the correction voltage values ​​of all pixels of the detector includes: performing plane fitting on the correction voltage values ​​of all pixels of the detector based on the least squares method.

[0058] Therefore, a quantifiable linear response benchmark model can be established for the array voltage surface of the detector, transforming the complex spatial response distortion analysis into a standard parameter optimization problem.

[0059] Specifically, first, let i be the X-axis coordinate, j be the Y-axis coordinate, and so on. Construct a surface of area voltage values ​​for the Z-axis coordinate, and set... The corresponding data points are ( , (This is for subsequent calculations.)

[0060] Let's establish the equation for the fitted plane:

[0061]

[0062] In the formula, Let be the slope of the fitted plane along the X-axis. Let be the slope of the fitted plane along the Y-axis. The intercept (constant term) of the fitted plane;

[0063] Establish the least squares estimation objective function:

[0064]

[0065] In the formula, n is the total number of pixels in the array, k∈[1,2,3……n];

[0066] The normal equation is derived from the least squares estimation objective function:

[0067]

[0068] In the formula, To design the matrix, For the observation vector, For coefficient vectors;

[0069] The design matrix is ​​as follows:

[0070] A=

[0071] in, The X-axis coordinates of the data points in the voltage value surface of the array are given. The Y-axis coordinates corresponding to the data points in the voltage value surface of the array;

[0072] The observation vector is:

[0073] Z=

[0074] in, The data points corresponding to the voltage values ​​in the surface array Axis coordinates;

[0075] The coefficient vector is:

[0076] = ,

[0077] Solving by the normal equation :

[0078]

[0079] The values ​​of a, b, and c can then be determined to derive the equation of the fitted plane.

[0080] Therefore, by establishing the fitting plane equation of the voltage value surface of the array and solving it using the least squares method, it can be ensured that the fitting plane can accurately characterize the overall response trend of the detector in space and effectively suppress the interference of random noise.

[0081] Furthermore, based on the plane fitting results, the fitted voltage value corresponding to each pixel of the detector is obtained, and the residual between the corrected voltage value and the fitted voltage value of each pixel is calculated using the following formula:

[0082] -

[0083] In the formula, The residual between the corrected voltage value and its fitted voltage value for each pixel. The fitted voltage value corresponding to each pixel;

[0084] The root mean square of the residual is calculated using the following formula:

[0085]

[0086] In the formula, The root mean square of the residual;

[0087] The nonlinearity of the voltage value surface of the array is calculated using the following formula:

[0088]

[0089] In the formula, The nonlinearity of the voltage value surface of the array, The average value of the correction voltage for the array is given.

[0090] Therefore, by averaging the square roots of the squared residuals of all pixels, the influence of random noise on the overall evaluation is effectively suppressed, while the sensitivity to systematic nonlinear distortion is enhanced. In addition, the dimensionless nonlinearity NL is obtained by normalizing the average value of the array correction voltage, which can reflect the non-uniformity of the intuitive detector response and also makes the detectors of different types and dynamic ranges comparable laterally.

[0091] Please refer to Figure 2 ,like Figure 2 As shown, the software is used to draw a comparison diagram of the voltage value surface of the array and the fitting plane, thereby allowing for an intuitive assessment of the overall nonlinearity of the detector array through the image.

[0092] Please refer to Figure 3 , Figure 3To provide a surface nonlinearity analysis report that records the nonlinearity data of the array voltage value surface, the overall nonlinearity of the detector array can be objectively evaluated by comparing the nonlinearity value of the array voltage value surface with the nonlinearity threshold.

[0093] Compared with existing technologies, the detector output voltage nonlinearity testing method provided by this invention has the following advantages:

[0094] The detector output voltage nonlinearity test method provided by this invention obtains different output voltage values ​​of the detector pixels by changing the integration time. Based on the elimination of the influence of pixel non-uniformity by two-point correction, a surface voltage value curve and a fitting plane are constructed. The nonlinearity is quantified by the ratio of the root mean square of the residual to the mean value of the surface correction voltage, which can realize an intuitive evaluation of the overall nonlinearity of the detector array.

[0095] The above description is only a description of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A method for testing the nonlinearity of detector output voltage, characterized in that, The method includes: The detector is placed in front of the black body, and the operating temperature of the black body is set to a preset temperature and the distance between the detector and the black body is set to be less than or equal to the preset distance. The output voltage value of each pixel of the detector under the first preset effective integration time and the second preset effective integration time, as well as the average output voltage of the array of the detector under the first preset effective integration time and the second preset effective integration time, are obtained respectively. For each pixel of the detector, the first correction coefficient and the second correction coefficient of the pixel are calculated using a two-point correction formula based on the output voltage value of the pixel under the first preset effective integration time and the second preset effective integration time, and the average output voltage of the detector array under the first preset effective integration time and the second preset effective integration time. The output voltage value of each pixel of the detector is obtained at a third preset effective integration time. For each pixel, the output voltage value of the pixel at the third preset effective integration time is corrected according to the first correction coefficient and the second correction coefficient of the pixel to obtain the corrected voltage value of the pixel. The average corrected voltage value of the detector array is obtained according to the average value of the corrected voltage values ​​of all pixels of the detector. Plane fitting is performed based on the corrected voltage values ​​of all pixels of the detector, and the fitted voltage value corresponding to each pixel of the detector is obtained based on the plane fitting result. The root mean square of the residual is calculated based on the corrected voltage values ​​and fitted voltage values ​​of all pixels of the detector, and the output voltage nonlinearity value of the detector is obtained based on the ratio of the root mean square of the residual to the mean value of the area array corrected voltage of the detector.

2. The detector output voltage nonlinearity testing method as described in claim 1, characterized in that, The step of acquiring the output voltage value of each pixel of the detector at the first preset effective integration time and the second preset effective integration time, as well as the average output voltage value of the detector array at the first preset effective integration time and the second preset effective integration time, includes: The detector is controlled to continuously acquire multiple frames of first detection data with an integration time of the first preset integration time under the optimal bias voltage condition, so as to obtain multiple first output voltage values ​​corresponding to each pixel of the detector. The detector is controlled to continuously acquire multiple frames of second detection data with an integration time of the second preset integration time under the optimal bias voltage condition, so as to obtain multiple second output voltage values ​​corresponding to each pixel of the detector. For each pixel of the detector, the output voltage value of the pixel under the first preset effective integration time is obtained based on the average of the multiple first output voltage values ​​corresponding to the pixel, and the output voltage value of the pixel under the second preset effective integration time is obtained based on the average of the multiple second output voltage values ​​corresponding to the pixel. The average output voltage of the detector array under the first preset effective integration time is obtained based on the average output voltage of all pixels of the detector under the first preset effective integration time. The average output voltage of the detector array under the second preset effective integration time is obtained based on the average output voltage of all pixels of the detector under the second preset effective integration time.

3. The detector output voltage nonlinearity testing method as described in claim 1, characterized in that, The step of acquiring the output voltage value of each pixel of the detector at a third preset effective integration time includes: The detector is controlled to continuously acquire multiple frames of third detection data with an integration time of the third preset integration time under the optimal bias voltage condition, so as to obtain multiple third output voltage values ​​corresponding to each pixel of the detector. For each pixel of the detector, the output voltage value of the pixel at the third preset effective integration time is obtained based on the average of the multiple third output voltage values ​​corresponding to the pixel.

4. The detector output voltage nonlinearity testing method as described in claim 1, characterized in that, The third preset effective integration time is greater than the second preset effective integration time, and the second preset effective integration time is greater than the first preset effective integration time.

5. The detector output voltage nonlinearity testing method as described in claim 1, characterized in that, The first preset effective integration time, the second preset effective integration time, and the third preset effective integration time are set according to the output voltage swing of the detector and the average value of the array bare voltage obtained by pre-calibration.

6. The detector output voltage nonlinearity testing method as described in claim 5, characterized in that, The output voltage swing and the average bare voltage of the detector are calibrated through the following process: The detector is placed in front of the black body, and the operating temperature of the black body is set to the preset temperature, and the distance between the detector and the black body is set to be less than or equal to the preset distance. The detector is controlled to continuously acquire multiple frames of fourth detection data with an integration time of minimum integration time under minimum bias voltage conditions, so as to obtain multiple fourth output voltage values ​​corresponding to each pixel of the detector. Under the optimal bias voltage condition, the integration time is adjusted until the array of the detector reaches saturation, so as to obtain the saturation integration time corresponding to the detector. The detector is controlled to continuously acquire multiple frames of fifth detection data with an integration time equal to the saturation integration time under optimal bias voltage conditions, so as to obtain multiple fifth output voltage values ​​corresponding to each pixel of the detector. For each pixel of the detector, the minimum output voltage value corresponding to the pixel is obtained based on the average of the multiple fourth output voltage values ​​corresponding to the pixel, and the maximum output voltage value corresponding to the pixel is obtained based on the average of the multiple fifth output voltage values ​​corresponding to the pixel. The average bare voltage of the detector array is obtained based on the average of the minimum output voltage values ​​corresponding to all pixels of the detector, and the average saturation voltage of the detector array is obtained based on the average of the maximum output voltage values ​​corresponding to all pixels of the detector. The output voltage swing of the detector is obtained based on the difference between the average saturation voltage of the detector array and the average bare voltage of the detector array.

7. The detector output voltage nonlinearity testing method as described in claim 1, characterized in that, The first correction coefficient and the second correction coefficient for each pixel are calculated using the following two-point correction formula: In the formula, i∈[1,2,3,…,M], M is the total number of rows in the detector's array, j∈[1,2,3,…,N], N is the total number of columns in the detector's array. The average output voltage of the detector array during the first preset effective integration time is denoted as . Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the first preset effective integration time. The average output voltage of the detector array during the second preset effective integration time is given. Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the second preset effective integration time. Let be the first correction coefficient for the pixel in the i-th row and j-th column of the detector's array. It is the second correction coefficient for the pixel in the i-th row and j-th column of the detector's array.

8. The detector output voltage nonlinearity testing method as described in claim 7, characterized in that, The correction voltage value for each pixel is calculated using the following formula: In the formula, Let be the correction voltage value of the pixel in the i-th row and j-th column of the detector array during the third preset effective integration time. Let be the output voltage value of the pixel in the i-th row and j-th column of the detector array during the third preset effective integration time.

9. The detector output voltage nonlinearity testing method as described in claim 1, characterized in that, Before performing plane fitting based on the corrected voltage values ​​of all pixels of the detector, the method further includes: For each pixel of the detector, if the difference between the correction voltage value of the pixel and the average of the correction voltage values ​​of its multiple neighboring pixels is within a preset range, the pixel is determined to be a normal pixel; otherwise, the pixel is determined to be a bad pixel. For each bad pixel in the detector, the average of the correction voltage values ​​of the normal pixels in the multiple neighboring pixels surrounding the bad pixel is taken as the new correction voltage value of the bad pixel.

10. The method for testing the nonlinearity of the detector output voltage as described in claim 1, characterized in that, The step of performing plane fitting based on the corrected voltage values ​​of all pixels of the detector includes: The correction voltage values ​​of all pixels of the detector are fitted in a plane using the least squares method.

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