Infrared thermal imager wide dynamic range testing device and method of use thereof

Abstract

The application discloses an infrared thermal imager wide dynamic range testing device and a use method thereof, and relates to the field of infrared thermal imaging testing devices.The device comprises a radiation source array, a radiation source controller, a lifting turntable, a data acquisition system and a computer; the radiation source array comprises several layers, the temperature gradually increases from top to bottom, each layer comprises a fixed temperature radiation source and a dynamic temperature radiation source, and the radiation sources in each layer are arranged in an arc shape.The application uses the arrangement of the layered radiation source array to effectively widen the radiation temperature range of the testing system, uses the combination of the fixed temperature radiation source and the dynamic temperature radiation source to quickly determine the approximate interval of the thermal imager response range for different types of thermal imagers with large dynamic range differences, effectively improves the testing efficiency, and uses the arc-shaped radiation source array structure in combination with the lifting turntable to realize automatic radiation source temperature adjustment and thermal imager pointing adjustment, effectively meeting the dynamic range testing requirements of the infrared thermal imaging system for low-temperature to ultrahigh-temperature scenes.

Description

Technical Field

[0001] This invention belongs to the field of infrared testing, specifically relating to a wide dynamic range testing device for infrared thermal imagers and its usage method. Background Technology

[0002] The development of infrared technology and the research and development and production of infrared imaging systems are inseparable from the performance testing and evaluation of infrared imaging systems. To ensure the imaging quality or temperature measurement accuracy of infrared thermal imagers, various parameters need to be tested, including dynamic range. Conventional infrared testing systems generally integrate tests for various parameters such as dynamic range, modulation transfer function, signal transfer function, spectral transfer function, minimum resolvable temperature difference, minimum detectable temperature difference, and noise equivalent temperature difference. The radiation source used is mainly in the form of a differential blackbody, which leads to many problems in dynamic range testing. First, the absolute temperature upper and lower limits of the blackbody are narrow, which cannot meet the testing requirements of thermal imagers with wide dynamic range, and thus cannot meet the requirements of thermal imagers for testing ultra-high temperature targets. Second, conventional testing systems generally operate in a normal temperature environment. When the blackbody is cooled to below normal temperature, condensation is likely to occur, and even frosting may occur when the blackbody is cooled to below zero degrees Celsius, causing the testing system to fail to meet the testing requirements of thermal imagers in low-temperature scenarios.

[0003] Based on the above problems, designing a device that can meet the parameter testing requirements of wide dynamic range thermal imagers is of great practical significance and meets the needs of users. Summary of the Invention

[0004] The purpose of this invention is to provide a wide dynamic range testing device for infrared thermal imagers and its usage method, so as to meet the dynamic range testing requirements of infrared thermal imaging systems for low temperature to ultra-high temperature scenarios.

[0005] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0006] An infrared thermal imager wide dynamic range testing device, the device includes a radiation source array, a radiation source controller, a lifting turntable, a data acquisition system and a computer;

[0007] The radiation source array consists of several layers, with the temperature gradually increasing from top to bottom. Each layer contains both fixed-temperature radiation sources and dynamic-temperature radiation sources, and the radiation sources in each layer are arranged in an arc shape.

[0008] The radiation source controller provides control signals to each radiation source, acquires the operating status of each radiation source, and uploads it to the computer.

[0009] The lifting turntable is used to fix the thermal imager under test and receive control commands from the computer to drive the thermal imager under test to lift and rotate, so as to point the thermal imager under test to different radiation sources.

[0010] The data acquisition system is used to acquire and transmit image data from the thermal imager under test to a computer;

[0011] The computer is used to control the lifting turntable and radiation source controller, receive and store the image data of the thermal imager under test, and calculate and display the dynamic range parameters of the thermal imager under test.

[0012] Furthermore, the radiation source array consists of 12 independent radiation sources in 4 layers with 3 sources in each layer. Each layer has 1 fixed-temperature radiation source and 2 dynamic-temperature radiation sources.

[0013] The top layer consists of a low-temperature surface-source blackbody, with radiation temperatures ranging from -30℃ to 10℃, 25℃, and 10℃ to 45℃ from left to right; the second layer consists of a medium-temperature surface-source blackbody, with radiation temperatures ranging from 45℃ to 200℃, 300℃, and 200℃ to 400℃ from left to right; the third layer consists of a high-temperature cavity blackbody, with radiation temperatures ranging from 400℃ to 700℃, 600℃, and 500℃ to 800℃ from left to right; and the bottom layer consists of an ultra-high-temperature cavity blackbody, with radiation temperatures ranging from 700℃ to 1050℃, 1050℃, and 1000℃ to 1500℃ from left to right.

[0014] Furthermore, the device also includes an anti-frost cover, which is used to isolate the low-temperature surface source blackbody with nitrogen.

[0015] Furthermore, the device also includes a temperature circulation duct for cooling the radiation source array.

[0016] Furthermore, the device also includes a guide rail, on which the lifting turntable is mounted.

[0017] A method of using the infrared thermal imager wide dynamic range testing device described above includes the following steps:

[0018] S1. The computer controls the fixed-temperature radiation sources in each layer of the radiation source array to reach the specified temperature through the radiation source controller.

[0019] S2. The computer-controlled lifting turntable points the thermal imager under test to a fixed temperature radiation source on each floor one by one, while recording the image data output by the thermal imager under test and determining the approximate range of the response range of the thermal imager under test.

[0020] S3. After determining the approximate range of the response range of the thermal imager under test, point the thermal imager under test to the dynamic temperature radiation source in that range, control the dynamic temperature radiation source in that range to change the radiation temperature until the output of the thermal imager under test is saturated, and acquire the image data of the thermal imager under test through the data acquisition system.

[0021] The dynamic range of the thermal imager under test is calculated using the following formula:

[0022]

[0023] Where DR is the dynamic range, V sat The saturation signal voltage, This represents the average noise voltage.

[0024] Furthermore, changing the radiation temperature of the radiation source is equivalent to changing the irradiation power. When the signal voltage of the thermal imager does not increase with the increase of the irradiation power, the corresponding signal voltage is the saturation signal voltage.

[0025] Furthermore, the average noise voltage is calculated as follows:

[0026]

[0027] Where M and N are the row and column resolutions, d and h are the overheated and dead pixels, and V N (i,j) represents the pixel noise voltage, calculated using the following formula:

[0028]

[0029] The above formula represents the value of V when F frames of image data are acquired under temperature T0. DS [(i,j),T0], and obtain V DS The average value of [(i,j),T0] is K is the system gain.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] This invention utilizes a layered radiation source array to effectively broaden the radiation temperature range of the testing system. By combining fixed-temperature and dynamic-temperature radiation sources, it can quickly determine the approximate range of the thermal imager's response range for different types of thermal imagers with significant differences in dynamic range, effectively improving testing efficiency. Furthermore, by using an arc-shaped radiation source array structure combined with a lifting turntable, it is possible to achieve automated adjustment of radiation source temperature and thermal imager pointing, effectively meeting the dynamic range testing requirements of infrared thermal imaging systems for low-temperature to ultra-high-temperature scenarios. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the infrared thermal imager wide dynamic range testing device;

[0033] Figure 2 This is a schematic diagram of the radiation source array structure;

[0034] Figure 3 This is a schematic diagram of the working principle of the infrared thermal imager wide dynamic range testing device.

[0035] In the diagram: 1-Radiation source controller, 2-Temperature circulation air duct, 3-Anti-frost cover, 4-Radiation source array, 5-Thermal imager under test, 6-Lifting turntable, 7-Guide rail, 8-Computer. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for explaining the invention and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.

[0037] The purpose of this invention is to provide a wide dynamic range testing device for thermal imaging systems, which can meet the dynamic range testing requirements of infrared thermal imaging systems from low temperature to ultra-high temperature scenarios.

[0038] like Figure 1 As shown, the infrared thermal imager wide dynamic range testing device mainly consists of a radiation source array 4, a radiation source controller 1, a data acquisition system, a computer 8, a display, and a lifting turntable 6.

[0039] The radiation source array 4 is the core device of the testing system, consisting of 12 independent radiation sources in 4 layers (3 sources per layer). Each layer has 1 fixed-temperature radiation source and 2 dynamic-temperature radiation sources, for a total of 4 fixed-temperature radiation sources and 8 dynamic-temperature radiation sources. The radiation source array structure is as follows: Figure 2 As shown, where Figure 2 (a) is a schematic diagram of the first-layer low-temperature blackbody structure. Figure 2 (b) is a schematic diagram of the second-layer intermediate-temperature blackbody structure. Figure 2 (c) is a schematic diagram of the third-layer high-temperature blackbody structure. Figure 2 (d) Schematic diagram of the bottom layer ultra-high temperature blackbody structure. Specifically: the top layer is a low temperature surface source blackbody, with radiation temperatures from left to right of -30℃~10℃, 25℃, and 10℃~45℃ respectively. To ensure that the low temperature does not frost, three pairs of anti-frost covers are used to isolate the low temperature blackbody with nitrogen filling; the second layer is a medium temperature surface source blackbody, with radiation temperatures from left to right of 45℃~200℃, 300℃, and 200℃~400℃ respectively; the third layer is a high temperature cavity blackbody, with radiation temperatures from left to right of 400℃~700℃, 600℃, and 500℃~800℃ respectively; the bottom layer is an ultra-high temperature cavity blackbody, with radiation temperatures from left to right of 700℃~1050℃, 1050℃, and 1000℃~1500℃ respectively. In addition, to ensure the temperature stability of the radiation source array 4 during operation, a temperature circulation air duct 2 was designed for the radiation source array 4, and air is drawn in through the temperature circulation air duct 2 to dissipate heat from the radiation source array 4.

[0040] The function of radiation source controller 1 is to provide control signals to each radiation source, acquire the working status of each radiation source, and upload it to computer 8.

[0041] The lifting turntable 6 is mounted on the guide rail 7. Its function is to fix the thermal imager 5 under test and receive control commands from the computer 8 to point the thermal imager 5 under test to different radiation sources.

[0042] The data acquisition system is a software system whose function is to acquire and transmit the image data of the thermal imager 5 to the computer 8.

[0043] The computer 8 is used to control the lifting turntable 6 and the radiation source controller 1, receive and store image data, and calculate and display the dynamic range parameters of the thermal imager 5 under test.

[0044] like Figure 3 As shown, the specific steps for using the wide dynamic range testing device are as follows:

[0045] (1) The computer controls the fixed-temperature radiation source in the middle of each of the four radiation sources to reach the specified temperature through the radiation source controller.

[0046] (2) The computer-controlled lifting turntable points the thermal imager under test to the blackbody in the middle of each layer one by one, while recording the image data output by the thermal imager and determining the approximate range of the thermal imager's response range.

[0047] (3) After determining the approximate range of the thermal imager's response range, point the thermal imager at the radiation source in that range, control the dynamic temperature radiation source in that range to change the radiation temperature until the thermal imager output is saturated, and acquire the image data of the thermal imager through the data acquisition system.

[0048] Calculate the dynamic range of the thermal imager under test as follows:

[0049]

[0050] Where DR is the dynamic range, V sat The saturation signal voltage, This represents the average noise voltage.

[0051] Changing the temperature of the radiation source alters the irradiation power. When the signal voltage of the thermal imager does not increase with increasing irradiation power, the corresponding signal voltage is called the saturation signal voltage. The average noise voltage is calculated as follows:

[0052]

[0053] Where M and N are the row and column resolutions of the thermal imaging system, d and h are the overheated pixels and dead pixels, respectively, and V N (i,j) represents the pixel noise voltage, calculated using the following formula:

[0054]

[0055] The above formula represents the value of V when F frames of image data are acquired under temperature T0. DS [(i,j),T0], and obtain V DS The average value of [(i,j),T0] is K is the system gain.

[0056] Specifically, in this embodiment, the radiation temperature of the testing device is divided into four segments. A fixed-temperature radiation source and a dynamic-temperature radiation source are set in each segment. The thermal imager under test is placed on a lifting turntable. The computer, through the radiation source control cabinet, controls each fixed-temperature radiation source to reach a specified temperature. The lifting turntable is controlled to point the thermal imager at the corresponding fixed-temperature radiation source, determining the approximate response range of the thermal imager. The radiation source control cabinet controls the dynamic radiation source within the corresponding temperature segment to begin variable-temperature output until the output of the thermal imager under test reaches saturation. Simultaneously, the computer acquires the thermal imager's output images throughout the process through a data acquisition system. Finally, the dynamic range of the thermal imager under test is calculated. The specific steps are as follows:

[0057] (1) Place the thermal imager to be tested on the lifting turntable.

[0058] (2) The computer controls the fixed-temperature radiation source to reach the specified radiation temperature through the radiation source controller.

[0059] (3) The computer-controlled lifting turntable directs the thermal imager to fixed temperature radiation sources at 25℃, 300℃, 600℃, and 1050℃ respectively, and simultaneously acquires 128 frames of corresponding thermal imager output images. DS [(i,j),T 25 ]、V DS [(i,j),T 300 ]、V DS [(i,j),T 600 ]、V DS [(i,j),T 1050 ].

[0060] (4) Calculate the output voltage V of the thermal imager under various fixed temperature radiation conditions. 25 V 300 V 600 V 1050 ,in:

[0061]

[0062] V 300 V 600 V 1050 The calculation method and V 25 same.

[0063] (5) Determine V 25 V 300 V 600 V 1050 The relationship with the full-well voltage of the thermal imager, assuming V 600 The thermal imager output has reached full-well voltage, V. 300 If the thermal imager output does not reach the full-well voltage, it can be determined that the radiation source temperature corresponding to the thermal imager's saturation response voltage is between 300℃ and 600℃.

[0064] (6) The computer controls the radiation source controller to turn on the second layer of 200℃~400℃ surface blackbody radiation source and the third layer of 400℃~700℃ cavity blackbody radiation source.

[0065] (7) Control the lifting turntable to point the thermal imager under test to a blackbody with a surface temperature of 200℃~400℃, gradually increase the temperature of the blackbody to 400℃, and calculate the output voltage of the thermal imager according to the method in step (4). If the output of the thermal imager has not reached saturation, point the thermal imager to a cavity blackbody radiation source with a temperature of 400℃~700℃, gradually increase the temperature to 600℃, and calculate the output voltage of the thermal imager according to the method in step (4). When the thermal imager just reaches the saturation output, the blackbody stops heating, collect the output of the thermal imager at this time, and calculate the saturation output voltage. In this embodiment, it is assumed that the thermal imager under test reaches the saturation output at a blackbody temperature of 550℃.

[0066] (8) Calculate the dynamic range of the thermal imager:

[0067]

[0068] Where V 550 This is the saturation signal voltage of the thermal imager. Average noise voltage:

[0069]

[0070] Where M and N are the row and column resolutions of the thermal imaging system, d and h are the overheated pixels and dead pixels, respectively, and V N (i,j) represents the pixel noise voltage.

[0071]

[0072] The above formula represents the image data V acquired at a blackbody temperature of 300℃, where F = 128 frames were collected. DS [(i,j),T 300 ], and obtain V DS [(i,j),T 300 The average of ] is K is the system gain.

[0073] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for using an infrared thermal imager wide dynamic range testing device, characterized in that, The infrared thermal imager wide dynamic range testing device includes a radiation source array, a radiation source controller, a lifting turntable, a data acquisition system, and a computer; The radiation source array consists of several layers, with the temperature gradually increasing from top to bottom. Each layer contains both fixed-temperature radiation sources and dynamic-temperature radiation sources, and the radiation sources in each layer are arranged in an arc shape. The radiation source controller provides control signals to each radiation source, acquires the operating status of each radiation source, and uploads it to the computer. The lifting turntable is used to fix the thermal imager under test and receive control commands from the computer to drive the thermal imager under test to lift and rotate, so as to point the thermal imager under test to different radiation sources. The data acquisition system is used to acquire and transmit image data from the thermal imager under test to a computer; The computer is used to control the lifting turntable and radiation source controller, receive and store the image data of the thermal imager under test, and calculate and display the dynamic range parameters of the thermal imager under test. The usage method includes the following steps: S1. The computer controls the fixed-temperature radiation sources in each layer of the radiation source array to reach the specified temperature through the radiation source controller. S2. The computer-controlled lifting turntable points the thermal imager under test to a fixed temperature radiation source on each floor one by one, while recording the image data output by the thermal imager under test, calculating the output voltage of the thermal imager under test under various fixed temperature radiation conditions, determining the relationship with the full-sink voltage of the thermal imager under test, and determining the approximate range of the response range of the thermal imager under test. S3. After determining the approximate range of the response range of the thermal imager under test, point the thermal imager under test to the dynamic temperature radiation source in that range, control the dynamic temperature radiation source in that range to change the radiation temperature until the output of the thermal imager under test is saturated, and acquire the image data of the thermal imager under test through the data acquisition system. The average noise voltage is calculated based on the image data, and the dynamic range of the thermal imager under test is calculated using the following formula: in, For dynamic range, The saturation signal voltage, This represents the average noise voltage.

2. The method of use according to claim 1, characterized in that, The radiation source array consists of 12 independent radiation sources in 4 layers with 3 sources in each layer. Each layer has 1 fixed-temperature radiation source and 2 dynamic-temperature radiation sources. The top layer consists of low-temperature surface-source blackbodies, with radiation temperatures ranging from -30℃ to 10℃, 25℃, and 10℃ to 45℃ from left to right. The second layer consists of medium-temperature surface-source blackbodies, with radiation temperatures ranging from 45℃ to 200℃, 300℃, and 200℃ to 400℃ from left to right. The third layer consists of high-temperature cavity blackbodies, with radiation temperatures ranging from 400℃ to 700℃, 600℃, and 500℃ to 800℃ from left to right. The bottom layer consists of ultra-high-temperature cavity blackbodies, with radiation temperatures ranging from 700℃ to 1050℃, 1050℃, and 1000℃ to 1500℃ from left to right.

3. The method of use according to claim 2, characterized in that, The device also includes an anti-frost cover, which is used to isolate the low-temperature surface source blackbody with nitrogen.

4. The method of use according to claim 1, characterized in that, The device also includes a temperature circulation duct for cooling the radiation source array.

5. The method of use according to claim 1, characterized in that, The device also includes guide rails, on which the lifting turntable is mounted.

6. The method of use according to claim 1, characterized in that, Changing the radiation temperature of the radiation source is equivalent to changing the irradiation power. When the signal voltage of the thermal imager does not increase with the increase of the irradiation power, the corresponding signal voltage is the saturation signal voltage.

7. The method of use according to claim 1, characterized in that, The average noise voltage is calculated as follows: in, and For row and column resolution, and For overheated pixels and dead pixels, The pixel noise voltage is calculated using the following formula: The above formula represents the temperature Data collection under certain conditions Frame image data and obtain The average is , This represents the system gain.

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