Radiance calculation method and calibration information acquisition device

Abstract

To provide a radiance calculation method or the like capable of calculating accurate radiance of an imaging object.SOLUTION: A radiance calculation method includes: a calibration information acquisition process for acquiring calibration information by a calibration information acquisition device 20; and an actual measurement process for imaging an imaging object by an infrared camera and calculating radiance on the basis of an element output, an element temperature, and calibration information. The calibration information acquisition process includes: a basic data acquisition process for imaging a calibration object by an infrared camera, and acquiring an element temperature and an element output at that time by a basic data acquisition part 22; a luminance versus output correlation acquisition process for acquiring a correlation between radiation luminance and an element output by a luminance versus output correlation acquisition part 25 on the basis of an element temperature Ft and an element output DLn; and an approximation coefficient calculation process for calculating approximation coefficients Aan, Abn, Acn, Ban, Bbn, Bcn, Can, Cbn, and Ccn as calibration information by an approximation coefficient calculation part 26 on the basis of the correlation between the radiance and the element output.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for calculating radiance from an output value detected by an infrared detection element in an infrared camera including an imaging unit configured by arranging a plurality of infrared detection elements on a two-dimensional plane, and a calibration information acquisition device for acquiring calibration information used when calculating this radiance.

Background Art

[0002] Conventionally, an infrared camera has been proposed in which the imaging unit is configured by a thermal uncooled infrared detection element called a bolometer (Patent Document 1). This infrared detection element changes its resistance value by absorbing infrared rays, and outputs a voltage value corresponding to the incident light amount by passing an electric current. When an imaging object is imaged, that is, when the infrared rays radiated from the imaging object are absorbed by the infrared detection element, a voltage value corresponding to the incident energy is output, and the temperature of the imaging object can be calculated by calibrating the output voltage value based on the sensitivity acquired in advance.

[0003] It is known that the sensitivity of this infrared detection element has individual differences. Conventionally, generally, two imaging objects with different known temperatures T1 and T2, for example, a blackbody furnace (a device approximating a blackbody), are imaged, and the output V of each infrared detection element n obtained at that time , n , , n , , n , n ,

[0004] , n , , n , n , n and the temperature T of the imaging object are used to calculate the sensitivity of each infrared detection element n.

[0004] More specifically, the relationship between the output V n and the temperature T is an approximation by the following linear function using the sensitivity coefficient a n , V2 n and the offset coefficient b n from the two-point data of V1 n at temperatures T1 and T2. V n = a n × T + b n Therefore, the temperature T of the imaging object can be calculated by the following formula. T=(V n -b n ) / a n =V n / a n -b n / a n =V n ×A n +B n

[0005] Furthermore, in conventional infrared cameras, a calibration sensitivity coefficient A is used to increase the processing speed. n (=1 / a n ), and offset coefficient B n (=-b n / a n The output V of each infrared detection element n is calculated in advance and stored in memory as a data table, and according to the above formula, n The temperature T of the object being imaged is calculated based on this.

[0006] Furthermore, the infrared detection element has the characteristic that its sensitivity changes as its own temperature rises due to changes in ambient temperature. For this reason, conventionally, the calibration sensitivity coefficient A is further adjusted according to the temperature of each infrared detection element. n and calibration offset coefficient B n The calibration sensitivity coefficient A is obtained in advance and stored as a data table, and the calibration sensitivity coefficient A is determined according to the infrared detection element temperature at the time of imaging. n and calibration offset coefficient B n This is used to calculate the temperature T of the object being imaged. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2010-193194 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the conventional infrared camera described above, the output V of the infrared detection element n is n And the infrared radiance Ld emitted from the object being imaged n These are treated as having a linear correlation, and under this linear relationship, the output V of the infrared detection element n n Based on this, the infrared radiance Ld emitted from the object being imaged n The system estimates (calculates) the radiance and then estimates (calculates) the temperature of the object being imaged from the obtained radiance.

[0009] However, infrared cameras have optical mechanisms such as lenses to focus the infrared radiation emitted from the object being imaged onto the infrared detection element n, and there are individual differences in the infrared detection element n, therefore the output DL of the infrared detection element n n (=V n ) and the infrared radiance Ld emitted from the object being imaged n The relationship between the two is not a linear one in the strict sense, as shown by the dashed line in Figure 5, but rather a nonlinear relationship that can be approximated by a quadratic or higher equation, as shown by the solid line.

[0010] Therefore, unlike conventional infrared cameras, the output DL of the infrared detection element n n Therefore, based on the linear relationship, the radiance Ld n Estimating this, the accurate radiance Ld of the object being imaged n It is not possible to estimate this, and consequently, it is not possible to estimate the accurate temperature of the object being imaged.

[0011] This invention has been made in view of the above circumstances, and compared to the conventional method, it provides more accurate radiance Ld of the object being imaged. n The objective is to provide a radiance calculation method that can estimate [the value of the radiance], and a calibration information acquisition device for performing this calculation. [Means for solving the problem]

[0012] The present invention, which solves the above problems, An infrared camera is used that includes an imaging unit having a plurality of n infrared detection elements arranged on a two-dimensional plane, and an element temperature detection sensor for detecting the temperature of the infrared detection elements, to measure the infrared radiance Ld emitted from the object being imaged. n A method for calculating, The radiance Ld n A calibration information acquisition process to obtain calibration information for calculating, The infrared camera is used to image the target object, and the output DL is generated from the infrared detection element. n , the element temperature Ft detected by the element temperature detection sensor, and the infrared radiance Ld emitted from the object being imaged based on the calibration information obtained in the calibration information acquisition step. n It consists of a measurement process to calculate, The calibration information acquisition process described above is: Using the infrared camera, a calibration object at a predetermined temperature is imaged, and the temperature Ft of the infrared detection element is obtained from the element temperature detection sensor, and the output DL is obtained from each infrared detection element. n The process of acquiring basic data to obtain, The temperature Ft and output DL obtained in the aforementioned basic data acquisition process. n Based on this, the radiance Ld emitted from the calibration object when the temperature Ft of the infrared detection element is at a predetermined temperature. n and the output DL from each infrared detection element n A process for acquiring luminance versus output correlation to obtain correlation with, The radiance Ld obtained in the luminance versus output correlation acquisition step n and output DL n Based on the correlation with, the approximate coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n It consists of a process for calculating an approximate coefficient and a process for calculating the coefficient, The aforementioned measurement process is, Imaging the object to be imaged using the infrared camera, obtaining the temperature Ft of the infrared detection element from the element temperature detection sensor, and obtaining the output DL from each infrared detection element n An actual measurement data acquisition step of obtaining the temperature Ft of the infrared detection element obtained in the actual measurement data acquisition step, and the approximation coefficients Aa n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n and Cc n , calculating the temperature correction coefficients a n , b n and c n according to the following formula 1 in the temperature correction coefficient calculation step; the output DL from the infrared detection element obtained in the actual measurement data acquisition step n , and the temperature correction coefficients a n , b n and c n calculated in the temperature correction coefficient calculation step, calculating the radiant luminance Ld n radiated from the object to be imaged according to the following formula 2 in the radiant luminance calculation step. The radiant luminance calculation method is composed of (Formula 1) a n = Aa n ·Ft 2 + Ab n ·Ft + Ac n b n = Ba n ·Ft 2 + Bb n ·Ft + Bc n c n = Ca n ·Ft 2 + Cb n ·Ft + Cc n (Formula 2) Ld n = a n ·DL n2 +b n ·DL n +c n However, n is a natural number of 1 or more, and is an eigenvalue corresponding to each of the infrared detection elements.

[0013] According to this radiation luminance calculation method, first, a calibration information acquisition step for acquiring calibration information for calculating the radiation luminance Ld n is executed.

[0014] In this calibration information acquisition step, first, a basic data acquisition step is executed, and the temperature Ft of the infrared detection element output from the element temperature detection sensor when imaging a calibration object at a predetermined temperature using the infrared camera, and the output DL n output from each of the infrared detection elements are acquired.

[0015] Next, the luminance-output correlation acquisition step is executed, and based on the temperature Ft and the output DL n acquired in the basic data acquisition step, the radiation luminance Ld n emitted from the calibration object when the temperature Ft of the infrared detection element is a predetermined temperature, and the output DL n from each of the infrared detection elements are acquired.

[0016] Then, the approximation coefficient calculation step is executed, and based on the correlation between the radiation luminance Ld <00​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​n , Cb n and Cc n This corresponds to the aforementioned calibration information.

[0017] In this way, after calibration information is acquired in the calibration information acquisition process, it becomes possible to perform actual measurements (actual measurement process) of the object to be measured (imaged object) using the infrared camera.

[0018] In this measurement process, the measurement data acquisition process is performed by imaging the target object using the infrared camera, the temperature Ft of the infrared detection element output from the element temperature detection sensor is acquired, and the output DL is obtained from each infrared detection element. n This is obtained.

[0019] Next, a temperature correction coefficient calculation step is performed, and the temperature Ft of the infrared detection element obtained in the actual measurement data acquisition step and the approximation coefficient Aa calculated in the calibration information acquisition step are used. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Based on this, the temperature correction coefficient a is calculated according to the above formula 1. n , b n and c n The following is calculated. Note that Equation 1 is a temperature correction coefficient a n , b n , c n This is a correlation formula that defines the correlation between the infrared detection element temperature (element temperature) Ft and the infrared detection element temperature.

[0020] Next, the radiance calculation process is performed, and the output DL from the infrared detection element acquired in the measured data acquisition process is recorded. n , and the temperature correction coefficient a calculated in the temperature correction coefficient calculation step n , b n and c n Based on this, the radiance Ld emitted from the object being imaged is calculated according to the above formula 2. nThe following is calculated. Note that formula 2 is based on the radiance Ld n and output DL n This is a correlation formula that defines the correlation between [the two factors].

[0021] Thus, according to the radiance calculation method of the present invention, the output DL of each infrared detection element is n And the infrared radiance Ld emitted from the object being imaged n The correlation with the output DL from each infrared detection element is defined by the quadratic equation Equation 2 above, and the output DL from each infrared detection element is defined. n Based on this, according to the above formula 2, the radiance Ld n Since it is designed to calculate (estimate) the radiance Ld based on a linear relationship, n Compared to the conventional method of calculating Ld, this method provides a more realistic and accurate calculation of radiance. n It is possible to calculate this.

[0022] Furthermore, the above calibration information acquisition process can be suitably performed by the following calibration information acquisition device. That is, this calibration information acquisition device is An infrared camera is used that includes an imaging unit having a plurality of n infrared detection elements arranged on a two-dimensional plane, and an element temperature detection sensor for detecting the temperature of the infrared detection elements, to measure the infrared radiance Ld emitted from the object being imaged. n A device for acquiring calibration information used when calculating, When a calibration object at a predetermined temperature is imaged by the infrared camera, the temperature Ft of the infrared detection element output from the element temperature detection sensor is obtained, and the output DL from each infrared detection element is also obtained. n A basic data acquisition unit that acquires the data, The temperature Ft and output DL acquired by the basic data acquisition unit are obtained in the aforementioned basic data acquisition unit. n Based on this, the radiance Ld emitted from the calibration object when the temperature Ft of the infrared detection element is at a predetermined temperature. n and the output DL from each infrared detection element n A luminance vs. output correlation acquisition unit that acquires the correlation with, The radiance Ld acquired in the luminance versus output correlation acquisition unit n and output DLn Based on the correlation with, the approximate coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n It consists of an approximation coefficient calculation unit that calculates the following, and

[0023] Furthermore, in the above method for calculating radiance, The calibration information acquisition process further includes: The temperature Ft and output DL of the infrared detection element obtained by the basic data acquisition process described above n Based on this, an output-to-temperature correlation acquisition process is performed to obtain an output-to-temperature correlation equation, Based on the output-temperature correlation equation obtained by the output-temperature correlation acquisition process, interpolation is performed to obtain the temperature Ft of the infrared detection element and the output DL. n The system includes an interpolation process for calculating correlation data with, The luminance versus output correlation acquisition step uses the temperature Ft and output DL obtained by the basic data acquisition step. n , as well as the temperature Ft and output DL calculated by the interpolation process. n Based on the radiance Ld n and the aforementioned output DL n An embodiment can be adopted that is configured to obtain a correlation with [the specified value].

[0024] Similarly, in the calibration information acquisition device described above, The temperature Ft and output DL of the infrared detection element are acquired by the basic data acquisition unit. n Based on this, an output-to-temperature correlation acquisition unit obtains an output-to-temperature correlation formula, Based on the output-to-temperature correlation equation obtained by the output-to-temperature correlation acquisition unit, interpolation processing is performed to obtain the temperature Ft of the infrared detection element and the output DL. n The system further comprises an interpolation processing unit that calculates correlation data with, The luminance-to-output correlation acquisition unit acquires temperature Ft and output DL obtained by the basic data acquisition unit.n , as well as the temperature Ft and output DL calculated by the interpolation processing unit. n Based on the radiance Ld n and the aforementioned output DL n An embodiment can be adopted that is configured to obtain a correlation with [the specified value].

[0025] In these embodiments, the temperature Ft of the infrared detection element and the output DL obtained by the basic data acquisition step (basic data acquisition unit) are... n Based on this, the output-to-temperature correlation acquisition process (output-to-temperature correlation acquisition unit) acquires the correlation equation between output and temperature.

[0026] Then, based on the output-temperature correlation formula obtained by the output-temperature correlation acquisition step (output-temperature correlation acquisition unit), interpolation processing is performed in the interpolation processing step (interpolation processing unit), and the temperature Ft of the infrared detection element and the output DL are interpolated. n Interpolation of correlation data is performed, and based on the correlation data with improved accuracy in this way, the luminance vs. output correlation acquisition process (luminance vs. output correlation acquisition unit) performs the radiance Ld n and the aforementioned output DL n A correlation is obtained with this.

[0027] Thus, according to this embodiment, the temperature Ft and output DL of the infrared detection element are n Since highly accurate and precise correlation data can be obtained, the temperature correction coefficient a according to the above formula 1 can be obtained. n , b n , c n The approximation coefficient Aa for calculating n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This improves accuracy, and consequently, allows for the calculation of more precise and accurate radiance of the object being imaged. Furthermore, it enables the acquisition of low-noise images with less variation between pixels. [Effects of the Invention]

[0028] As described above, according to the radiance calculation method of the present invention, the output DL of each infrared detection element is n And the infrared radiance Ld emitted from the object being imaged n The correlation with the output DL from each infrared detection element is defined by the quadratic equation Equation 2 above, and the output DL from each infrared detection element is defined. n Based on this, according to the above formula 2, the radiance Ld n Since it is designed to calculate (estimate) the radiance Ld based on a linear relationship, n Compared to the conventional method of calculating Ld, this method provides a more realistic and accurate calculation of radiance. n It is possible to calculate this.

[0029] Furthermore, according to the calibration information acquisition device of the present invention, a more realistic and accurate radiance Ld n Calibration information for calculating can be suitably obtained. [Brief explanation of the drawing]

[0030] [Figure 1] This is a schematic diagram illustrating an infrared camera and a calibration information acquisition device according to one embodiment of the present invention. [Figure 2] This is a block diagram showing the configuration of the infrared camera according to this embodiment. [Figure 3] This is a block diagram showing the configuration of the calibration information acquisition device according to this embodiment. [Figure 4] This is an explanatory diagram showing the relationship between radiance and blackbody temperature. [Figure 5] This is an explanatory diagram showing the relationship between radiance and element output. [Figure 6] This is an explanatory diagram showing the structure of the infrared camera according to this embodiment. [Figure 7] This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 8] This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 9]This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 10] This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 11] This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 12] This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 13] This is an explanatory diagram illustrating the processing in the calibration information acquisition device according to this embodiment. [Figure 14] This is a block diagram showing the configuration of a calibration information acquisition device according to another embodiment of the present invention. [Modes for carrying out the invention]

[0031] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. Figure 1 is a schematic diagram illustrating an infrared camera and a calibration information acquisition device according to one embodiment of the present invention, Figure 2 is a block diagram showing the configuration of the infrared camera according to this embodiment, and Figure 3 is a block diagram showing the configuration of the calibration information acquisition device according to this embodiment. Details of each part will be described below.

[0032] In this example, as shown in Figure 1, first, the infrared camera 1 is placed inside the constant temperature case 100 and connected to the calibration information acquisition device 20. The calibration information acquisition device 20 acquires calibration information, and the obtained calibration information is stored in the infrared camera 1. After this, the infrared camera 1 is removed from the constant temperature case 100, an object to be imaged is captured, and data regarding its surface temperature is measured. In Figure 1, the constant temperature case 100 is temperature-controlled by a Peltier element 101. Reference numeral 103 denotes a black body, which is adjusted to a predetermined temperature by an appropriate temperature controller (not shown). A shutter 102 is placed between the black body 103 and the lens 3 of the infrared camera 1.

[0033] <Infrared camera> As shown in Figures 1 and 2, the infrared camera 1 in this example consists of a housing 2, a lens 3, an imaging unit 6, an element temperature detection sensor 7, and a data processing unit 8, all of which are located within the housing 2. The data processing unit 8 is configured to be connectable to the calibration information acquisition device 20.

[0034] The lens 3 is positioned in the opening of the housing 2 so as to close the opening, and focuses infrared light emitted from the object to be imaged onto the imaging unit 6, which is arranged at appropriate intervals behind it.

[0035] The imaging unit 6 has a plurality of infrared detection elements 6a arranged in double rows and double columns on a two-dimensional plane. n It is equipped with an infrared detection element 6a. n This is a thermal, uncooled element called a bolometer, and each infrared detection element 6a n The device outputs a voltage value corresponding to the amount of incident light and inputs it to the data processing unit 8. The imaging unit 6 is also equipped with an element temperature detection sensor 7, which detects each infrared detection element 6a. n Temperature data is input to the data processing unit 8. Note that this element temperature detection sensor 7 is controlled by each infrared detection element 6a n The overall temperature is detected. Furthermore, n is a natural number greater than or equal to 1, corresponding to the number of infrared detection elements, and the specific numerical value is an eigenvalue corresponding to each of the aforementioned infrared detection elements. Unless otherwise specified, n is used with the same intent below.

[0036] The data processing unit 8 consists of A / D converters 9 and 10, an approximation coefficient storage unit 12, a temperature correction coefficient calculation unit 13, a temperature correction coefficient storage unit 14, a radiance calculation unit 15, a temperature data calculation unit 16, a D / A converter 17, and an input / output interface 18, among others.

[0037] Furthermore, this data processing unit 8 can be composed of a computer including a CPU, RAM, ROM, etc. Specifically, the A / D converters 9, 10, temperature correction coefficient calculation unit 13, radiance calculation unit 15, temperature data calculation unit 16, D / A converter 17, and input / output interface 18 can be configured such that their functions are realized by a computer program. Alternatively, the A / D converters 9, 10, temperature correction coefficient calculation unit 13, radiance calculation unit 15, temperature data calculation unit 16, D / A converter 17, and input / output interface 18 can each be realized by an electronic device equipped with appropriate electronic circuits. In addition, the approximation coefficient storage unit 12 and temperature correction coefficient storage unit 14 can be composed of appropriate storage media such as RAM.

[0038] The A / D converter 9 receives the infrared detection element 6a output from the element temperature detection sensor 7. n The A / D converter 10 receives temperature data from each infrared detection element 6a, performs A / D conversion, inputs the converted element temperature Ft to the temperature correction coefficient calculation unit 13, and transmits it to the input / output interface 18 which is selectively connected via the changeover switch 11. n The output from is converted using A / D conversion, and the converted element output DL n This is transmitted to the radiance calculation unit 15 or input / output interface 18, which is selectively connected via the changeover switch 11.

[0039] The approximation coefficient storage unit 12 receives the approximation coefficient Aa as calibration information input from the calibration information acquisition device 20 via the input / output interface 18. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This is a functional unit that stores [something].

[0040] The aforementioned approximation coefficient Aa n Ab n Ac n Ban , Bb n , Bc n Ca n , Cb n and Cc n Each infrared detection element 6a n Output (element output) DL n And the infrared radiance Ld emitted from the object being imaged n When the correlation with is defined by the quadratic equation (correlation equation) in Equation 1 below, each temperature correction coefficient a in the said correlation equation n , b n , c n This is a coefficient used to calculate [the value]. (Equation 1) Ld n =a n • DL n 2 +b n • DL n +c n Furthermore, radiance Ld n This is the infrared detection element 6a n This is the radiance of the imaged object in the corresponding portion.

[0041] Specifically, the approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Based on the element temperature Ft, the temperature correction coefficient a is calculated using the quadratic equation (correlation equation) in Equation 2 below. n , b n , c n This is a coefficient used when calculating [the value]. (Equation 2) a n =Aa n · Ft 2 +Ab n · Ft+Ac n b n =Ba n · Ft 2 +Bb n Ft+Bc n c n =Ca n · Ft 2 +Cb n Ft+Cc n

[0042] According to the inventors' findings, each infrared detection element 6a n Output DL n And the infrared radiance Ld emitted from the object being imaged n This is because the relationship is not linear as shown by the dashed line in Figure 5, but nonlinear as shown by the solid line. This is because the infrared radiation emitted from the object being imaged is detected by the infrared detection element 6a n There is an optical mechanism such as lens 3 for focusing light (see Figure 6), and also an infrared detection element 6a n This is because there are individual differences. Therefore, in this embodiment, the element output DL is determined according to the above equation 1, which is a quadratic equation. n Therefore, the radiance Ld of the object being imaged n We decided to calculate (estimate) this. Furthermore, this approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n The significance and calculation method will be explained in detail later when describing the calibration information output device 20. Also, in Figure 6, reference numeral 4 is a holding part that holds the lens 3, and reference numeral 5 is a holding part fixed to the holding part 4 that holds the imaging unit 6.

[0043] The temperature correction coefficient calculation unit 13 receives the element temperature Ft output from the element temperature detection sensor 7 and input via the A / D converter 9, and the approximation coefficient Aa stored in the approximation coefficient storage unit 12. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc nBased on this, the temperature correction coefficient a is calculated according to the above formula 2. n , b n , c n The calculated temperature correction coefficient a is calculated. n , b n , c n The process involves storing the result in the temperature correction coefficient storage unit 14.

[0044] The radiance calculation unit 15 receives the element output DL, which is output from each of the infrared detection elements 6a and input via the A / D converter 10. n , and the temperature correction coefficient a stored in the temperature correction coefficient storage unit 14 n , b n , c n Based on this, according to the above formula 1, the radiance Ld n Perform the calculation process.

[0045] Furthermore, the temperature data calculation unit 16 calculates the radiance Ld calculated by the radiance calculation unit 15. n Based on this, a process is performed to calculate the temperature of the part of the object corresponding to each infrared detection element 6a of the object being imaged. n The conversion from this to temperature data can be calculated, for example, using the inverse function of Equation 3 described later. It is preferable that this temperature data be expressed in Celsius.

[0046] The D / A converter 22 is a processing unit that converts temperature data into analog data (image data), and the image data thus converted is output to the outside via the input / output interface 18. The image data can be a grayscale image or a color image composed of RGB components.

[0047] <Calibration information acquisition device> As shown in Figure 3, the calibration information acquisition device 20 consists of an input / output interface 21, a basic data acquisition unit 22, an output-to-temperature correlation acquisition unit 23, an interpolation processing unit 24, a brightness-to-output correlation acquisition unit 25, and an approximation coefficient calculation unit 26, and the calibration information is the approximation coefficient Aa n Ab nAc n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This is a device configured to acquire [something].

[0048] Furthermore, this calibration information acquisition device 20 can be composed of a computer including a CPU, RAM, ROM, etc., and the input / output interface 21, basic data acquisition unit 22, output vs. temperature correlation acquisition unit 23, interpolation processing unit 24, luminance vs. output correlation acquisition unit 25, and approximation coefficient calculation unit 26 can each be configured so that their functions are realized by a computer program.

[0049] As described above, the calibration information acquisition device 20 is connected to the infrared camera 1 while the infrared camera 1 is housed in the constant temperature case 100 shown in Figure 1, and acquires basic data from the infrared camera 1 as shown in Figure 7.

[0050] The basic data acquisition unit 22 receives the element temperature Ft and element output DL from the infrared camera 1 via the input / output interface 21. n This is a functional unit that acquires the following data. As shown in Figure 7, the basic data is obtained by setting the temperature of the constant temperature case 100 to four stages (Rt1 to Rt4) in 10°C intervals, for example from 10°C, and setting the temperature of the blackbody 103 to three stages (T1 to T3) in 10°C intervals, for each element temperature Ft1 to Ft4, opening the shutter 102 when the temperature of the blackbody 103 is T1 to T3, for each infrared detection element 6a n Element output DL output from n T1~DL n This is T3. Note that the temperature interval and set temperature are merely examples and are not limiting.

[0051] The output-to-temperature correlation acquisition unit 23 acquires the infrared detection element 6a acquired by the basic data acquisition unit 22. n The element temperature Ft and the output DL of each element.n Based on this, a correlation equation between output and temperature is obtained. The basic data obtained by the basic data acquisition unit 22 is used for the element output DL n The relationship between this and the element temperature Ft is as shown in Figure 8.

[0052] In Figure 8, each infrared detection element 6a n Element output DL n The correlation between and the element temperature Ft can be approximated by the following approximate formulas when the temperature of the blackbody 103 is T1, T2, and T3, respectively. DL n T1=A n1 · Ft 3 +B n1 · Ft 2 + C n1 Ft+D n1 DL n T2=A n2 · Ft 3 +B n2 · Ft 2 + C n2 Ft+D n2 DL n T3=A n3 · Ft 3 +B n3 · Ft 2 + C n3 Ft+D n3 Note that the coefficient A in each approximation formula n1 ~A n3 B n1 ~B n3 , C n1 ~C n3 , D n1 ~D n3 These can each be calculated using methods such as the least squares method. However, the approximation formula is not limited to this cubic equation; a quadratic equation or a higher-order equation of degree 4 or higher may also be used.

[0053] The interpolation processing unit 24 is a functional unit that performs data interpolation using the above-mentioned equations obtained by the output-temperature correlation acquisition unit 23. Figure 9 shows an example of interpolating data between Ft1 and Ft2. In Figure 9, the values ​​plotted as black circles are measured values, and the values ​​plotted as white circles are interpolated values. In this example, interpolation is performed every 2.5°C between Ft1 and Ft2, but this is just one example and is not limited to this. Interpolation may also be performed between Ft2 and Ft4.

[0054] The luminance-to-output correlation acquisition unit 25 acquires the element temperature Ft and element output DL obtained by the basic data acquisition unit 22. n , as well as the element temperature Ft and element output DL calculated by the interpolation processing unit 24. n Based on the radiance Ld n and the aforementioned output DL n This is a functional unit that obtains correlations with [the specified value].

[0055] First, the luminance-to-output correlation acquisition unit 25 calculates the radiance of the blackbody 103 for each temperature T1 to T3 of the blackbody 103 according to the following formula 3. (Equation 3) However, Lt is the radiance (W·sr -1 ·m -2 ) and Ld corresponds to the value obtained by scaling Lt to a digital level (2 to the power of n). Furthermore, λ is the wavelength (m) of the radiation emitted from the object, and λ1 to λ2 are the sensitivity wavelength range of the infrared detection element 6a. Furthermore, T is the absolute temperature (K) of the object, and corresponds to the temperature of the blackbody 103 and the object being imaged. Furthermore, C1 and C2 are emission constants, C1=c 2 h = 5.9548 × 10 -17 (W·m 2 ) C1 = ch / k = 0.014388 (m·K) Furthermore, c is the speed of light in a vacuum (c = 2.99792458 × 10⁻¹⁸). 8 m·s -1), h is Planck's constant (h = 6.6256 × 10⁻¹⁶). -34 J·s), where k is Boltzmann's constant (k = 1.38054 × 10⁻¹⁴). -23 J.K. -1 )

[0056] Furthermore, as can be seen from equation 3 above, the radiance Ld of blackbody 103 n The radiance LdT1 to LdT3 for each temperature T1 to T3 of the blackbody 103 is obtained as a unique value. Then, the luminance-to-output correlation acquisition unit 25 obtains the radiance LdT1 to LdT3 for each temperature T1 to T3 of the blackbody 103, and the radiance Ld n and the aforementioned output DL n The relationship is obtained for each element temperature Ft.

[0057] The radiance Ld n and the aforementioned output DL n The correlation with is shown in Figure 10. In Figure 10, the element temperature Ft is Ft1 and Ft 1+1 , Ft 1+2 , Ft 1+3 , the radiance Ld when Ft2 n and the aforementioned output DL n The correlation is shown, and each correlation can be approximated by the following quadratic equation. Note that the element temperature Ft 1+1 , Ft 1+2 , Ft 1+3 This is an interpolated value. Ld nFt1 =a nFt1 • DL nFt1 2 +b nFt1 • DL nFt1 +c nFt1 Ld nFt1+1 =a nFt1+1 • DL nFt1+1 2 +b nFt1+1 • DL nFt1+1 +c nFt1+1 Ld nFt1+2 =a nFt1+2 • DL nFt1+2 2 +b nFt1+2 • DL nFt1+2 +c nFt1+2 LdnFt1+3 =a nFt1+3 • DL nFt1+3 2 +b nFt1+3 • DL nFt1+3 +c nFt1+3 Ld nFt2 =a nFt2 • DL nFt2 2 +b nFt2 • DL nFt2 +c nFt2 However, the approximation formula is not limited to this quadratic equation; it may also be approximated by a higher-order equation of degree two or higher.

[0058] In the above equation, Ld nFt1 This is the radiance when the element temperature is Ft1, and similarly, Ld nFt1+1 The element temperature is Ft 1+1 The radiance at that time, Ld nFt1+2 The element temperature is Ft 1+2 The radiance at that time, Ld nFt1+3 The element temperature is Ft 1+3 The radiance at that time, Ld nFt2 This is the radiance when the element temperature is Ft2. Also, DL nFt1 This is the element output when the element temperature is Ft1, and similarly, DL nFt1+1 The element temperature is Ft 1+1 Element output at that time, DL nFn1+2 The element temperature is Ft 1+2 Element output at that time, DL nFt1+3 The element temperature is Ft 1+3 Element output at that time, DL nFt2 This is the element output when the element temperature is Ft2.

[0059] Furthermore, the above a nFt1 a nFt1+1 a nFt1+2 a nFt1+3 a nFt2 , b nFt1 , b nFt1+1 , b nFt1+2 , b nFt1+3 , b nFt2 , c nFt1 , c nFt1+1 , c nFt1+2 , cnFt1+3 , +c nFt2 is the temperature correction coefficient for defining the correlation between the radiation luminance Ld 1+1 and the output DL 1+2 when the element temperatures Ft are Ft1, Ft 1+3 , Ft n and Ft2 respectively. n and the output DL

[0060] The approximation coefficient calculation unit 26 is based on the correlation data between the radiation luminance Ld n and the output DL n obtained by the luminance-to-output correlation acquisition unit 25, and obtains the correlation relationship between each temperature correction coefficient a n , b n , c n and the element temperature Ft. From the obtained correlation relationship, the approximation coefficients Aa n , b n , c n for calculating a n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n and Cc n are calculated.

[0061] Fig. 11 shows the relationship between the coefficient a n and the element temperature Ft, Fig. 12 shows the relationship between the coefficient b n and the element temperature Ft, and Fig. 13 shows the relationship between the coefficient c n and the element temperature Ft. As can be seen from these, the coefficients a n , b n , c n are approximated by the following mathematical formulas respectively. a n = Aa n · Ft 2 + Ab n · Ft + Ac n b n = Ba ) n · Ft 2 + Bb n · Ft + Bcn c n =Ca n ·Ft 2 +Cb n ·Ft+Cc n

[0062] And the approximation coefficients Aa n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n , Cc n in each approximation formula can be calculated by a method such as the least squares method. The approximation coefficient calculation unit 16 transmits the approximation coefficients Aa n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n , Cc n thus calculated to the infrared camera 1 via the input / output interface 21. The infrared camera 1 stores the transmitted approximation coefficients Aa n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n , Cc n in the approximation coefficient storage unit 12 via the input / output interface 18.

[0063] According to the infrared camera 1 and the calibration information acquisition device 20 of this example having the above configuration, first, after the infrared camera 1 is housed in the constant temperature case 100 and connected to the calibration information acquisition device 20, the following calibration information acquisition process is executed.

[0064] Specifically, first, with the temperature of the constant temperature case 100 and the temperature of the blackbody 103 set to predetermined temperatures, the infrared camera 1 images the blackbody 103, and the calibration information acquisition device 2 then records the element temperature Ft and element output DL obtained at this time. n The basic data acquisition unit 22 acquires this data from the infrared camera 1 as basic data (basic data acquisition process).

[0065] Next, the calibration information acquisition device 2 acquires the infrared detection element 6a acquired by the basic data acquisition unit 22. n The element temperature Ft and element output DL n Based on this, the output vs. temperature correlation acquisition unit 23 acquires the element output DL n After obtaining the correlation equation between the element temperature Ft (output vs. temperature correlation acquisition process), the obtained element output DL n Based on the correlation equation between the element temperature Ft, the interpolation processing unit 24 calculates the element output DL. n The process of interpolating the correlation data between the element temperature Ft is performed (interpolation process).

[0066] Next, the calibration information acquisition device 2 acquires the element temperature Ft and element output DL obtained by the basic data acquisition unit 22. n , as well as the element temperature Ft and element output DL calculated by the interpolation processing unit 24. n Based on this, the luminance versus output correlation acquisition unit 25 acquires the radiance Ld n and the element output DL n The correlation is obtained (luminance vs. output correlation acquisition process).

[0067] Next, the calibration information acquisition device 2 acquires the radiance Ld n and element output DL n Based on the correlation, the approximation coefficient calculation unit 26 calculates the approximation coefficient Aa as calibration information. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc nAfter calculating (approximation coefficient calculation process), the calculated approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n The process involves storing the result in the approximate coefficient storage unit 12 of the infrared camera 1.

[0068] Then, after performing the calibration information acquisition process in cooperation with the infrared camera 1 and the calibration information acquisition device 20 as described above, the infrared camera 1 is used to image the target object, thereby acquiring the infrared radiance Ld emitted from the target object. n The measurement process for calculating the result is then performed.

[0069] Specifically, first, the infrared camera 1 is used to image the target object, and at that time, the element temperature Ft of the infrared detection element 6a detected by the infrared detection sensor 7 and the element output DL output from each infrared detection element 6a are determined. n However, these are acquired as actual measurement data after passing through A / D converters 9 and 10 (actual measurement data acquisition process).

[0070] The acquired element temperature Ft is input to the temperature correction coefficient calculation unit 13, and the input element temperature Ft and the approximation coefficient Aa stored in the approximation coefficient storage unit 12 are used in the temperature correction coefficient calculation unit 13. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Based on this, the temperature correction coefficient a is calculated according to the above formula 2. n , b n , c n The calculated temperature correction coefficient a is calculated. n , b n , c nThe process of storing the result in the temperature correction coefficient storage unit 14 is performed (temperature correction coefficient calculation step).

[0071] Meanwhile, the acquired element output DL n The input is passed to the radiance calculation unit 15, and the input element output DL is processed by the radiance calculation unit 15. n , and the temperature coefficient a stored in the temperature coefficient storage unit 14 n , b n and c n Based on this, according to the above formula 1, the radiance Ld of the object to be imaged is calculated. n This is calculated (radiance calculation process).

[0072] Next, in the temperature data calculation unit 16, the radiance Ld calculated in the radiance calculation unit 15 n Based on this, temperature data of the object being imaged is generated, and by converting the generated temperature data into analog data using the D / A converter 17, grayscale images and color images are generated.

[0073] As described above, according to this example, the element output DL of each infrared detection element 6a n And the infrared radiance Ld emitted from the object being imaged n The correlation with the above equation 1, which is a quadratic equation, is defined by the element output DL from each infrared detection element 6a. n Based on the above formula 1, the radiance Ld n Since it is designed to calculate (estimate) the radiance Ld based on a linear relationship, n Compared to the conventional method of calculating Ld, this method provides a more realistic and accurate calculation of radiance. n This allows for the calculation of the temperature of the object being imaged, and consequently, enables the calculation of a more accurate temperature of the object compared to conventional methods.

[0074] Furthermore, according to this example, the interpolation processing by the interpolation processing unit 24 is performed based on the output-temperature correlation formula acquired by the output-temperature correlation acquisition unit 23, and the element temperature Ft and element output DL of the infrared detection element 6a are obtained. nInterpolation of the correlation data is performed, and based on the correlation data with improved accuracy in this way, the luminance vs. output correlation acquisition unit 25 performs the radiance Ld n and the aforementioned output DL n A correlation is obtained with this.

[0075] Thus, according to this example, the element temperature Ft and element output DL of the infrared detection element 6a are... n Since highly accurate and precise correlation data can be obtained, the temperature correction coefficient a according to the above formula 2 can be obtained. n , b n , c n The approximation coefficient Aa for calculating n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This improves accuracy, and consequently, allows for the calculation of a more precise and accurate temperature of the object being imaged. Furthermore, it enables the acquisition of low-noise images with less variation between pixels.

[0076] Although one embodiment of the present invention has been described above, the specific embodiments that the present invention can take are not limited to the embodiments described above.

[0077] For example, in the above example, the calibration information acquisition device 20 is provided with an output-to-temperature correlation acquisition unit 23 and an interpolation processing unit 24, which acquire the element temperature Ft and the element output DL. n Although we attempted to interpolate the correlation data with this, this is not the only way to do so, and a reasonably accurate approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc nWhen it is possible to calculate, as shown in FIG. 14, the calibration information acquisition device 20' in a mode where the output vs. temperature correlation acquisition unit 23 and the interpolation processing unit 24 are omitted can be used.

[0078] Also, in the above example, in the infrared camera 1, the temperature data calculation unit 16 is provided. However, when generating image data from the radiation luminance Ld calculated by the radiation luminance calculation unit 15 n the temperature data calculation unit 16 shown in FIG. 2 can be omitted.

[0079] Also, in the infrared camera 1 of the above example, when adopting a mode of directly outputting the radiation luminance Ld calculated by the radiation luminance calculation unit 15 n to the outside via the input / output interface 18, the temperature data calculation unit 16 and the D / A converter 17 shown in FIG. 2 can be omitted.

Explanation of Reference Numerals

[0080] 1 Infrared camera 2 Housing 3 Lens 6 Imaging unit 6a Infrared detection element 7 Element temperature detection sensor 8 Data processing unit 9, 10 A / D converter 11 Switching switch 12 Approximation coefficient storage unit 13 Temperature correction coefficient calculation unit 14 Temperature correction coefficient storage unit 15 Radiation luminance calculation unit 16 Temperature data calculation unit [[ID=4,6]] 17 D / A converter 18 Input / output interface 20 Calibration information acquisition device 22 Basic data acquisition unit 23 Output vs. temperature correlation acquisition unit 24 Interpolation processing unit 25 Luminance vs. output correlation acquisition unit 26 Approximation coefficient calculation unit

Claims

1. An infrared camera is used to capture the infrared radiance Ld emitted from an object being imaged, using an imaging unit having a plurality of n infrared detection elements arranged on a two-dimensional plane, and an element temperature detection sensor that detects the temperature of the infrared detection elements. ｎ A method for calculating, The radiance Ld ｎ A calibration information acquisition process to obtain calibration information for calculating, The infrared camera is used to image the target object, and the output DL from the infrared detection element ｎ , the element temperature Ft detected by the element temperature detection sensor, and the infrared radiance Ld emitted from the object being imaged based on the calibration information obtained in the calibration information acquisition step. ｎ It consists of a measurement process to calculate, The calibration information acquisition process described above is: Using the infrared camera, a calibration object at a predetermined temperature is imaged, and the temperature Ft of the infrared detection element is obtained from the element temperature detection sensor, as well as the output DL from each infrared detection element. ｎ The process of acquiring basic data to obtain, The temperature Ft and output DL obtained in the aforementioned basic data acquisition process. ｎ Based on this, the radiance Ld emitted from the calibration object when the temperature Ft of the infrared detection element is at a predetermined temperature. ｎ and the output DL from each infrared detection element ｎ A process for acquiring luminance versus output correlation to obtain correlation with, The radiant luminance Ld obtained in the luminance-to-output correlation acquisition step ｎ and the output DL ｎ Based on the correlation between them, an approximation coefficient calculation step for calculating the approximation coefficients Aa ｎ , Ab ｎ , Ac ｎ , Ba ｎ , Bb ｎ , Bc ｎ , Ca ｎ , Cb ｎ and Cc ｎ and is composed of an approximation coefficient calculation step The aforementioned measurement process is, The infrared camera is used to image the target object, and the temperature Ft of the infrared detection element is obtained from the element temperature detection sensor, and the output DL is obtained from each infrared detection element. ｎ The process of acquiring actual measurement data, The temperature Ft of the infrared detection element obtained in the measurement data acquisition step, and the approximation coefficient Aa calculated in the calibration information acquisition step. ｎ Ab ｎ , Ac ｎ Ba ｎ , Bb ｎ , Bc ｎ Ca ｎ , Cb ｎ and Cc ｎ Based on this, the temperature correction coefficient a is calculated according to the following formula 1. ｎ , b ｎ and c ｎ A process for calculating a temperature correction coefficient, The output DL from the infrared detection element acquired in the above measurement data acquisition process. ｎ , and the temperature correction coefficient a calculated in the temperature correction coefficient calculation step ｎ , b ｎ and c ｎ Based on this, the radiance Ld emitted from the object being imaged is calculated according to the following formula 2. ｎ A method for calculating radiance, characterized by comprising a radiance calculation step for calculating [a certain value]. (Equation 1) a ｎ =Aa ｎ ・Ft ２ +Ab ｎ ・Ft+Ac ｎ b ｎ =Ba ｎ ・Ft ２ +Bb ｎ ・Ft+Bc ｎ c ｎ =Ca ｎ ・Ft ２ +Cb ｎ ・Ft+Cc ｎ (Equation 2) Ld ｎ =a ｎ ・DL ｎ ２ +b ｎ ・DL ｎ +c ｎ However, n is a natural number greater than or equal to 1, and is an eigenvalue corresponding to each of the infrared detection elements.

2. The calibration information acquisition process further includes: The temperature Ft and output DL of the infrared detection element obtained by the basic data acquisition process described above. ｎ Based on this, an output-to-temperature correlation acquisition process is performed to obtain an output-to-temperature correlation equation, Based on the output-temperature correlation equation obtained by the output-temperature correlation acquisition process, interpolation is performed to determine the temperature Ft of the infrared detection element and the output DL. ｎ The system includes an interpolation process for calculating correlation data with, The luminance versus output correlation acquisition step involves the temperature Ft and output DL obtained by the basic data acquisition step. ｎ , as well as the temperature Ft and output DL calculated by the interpolation process. ｎ Based on the radiance Ld ｎ and the output DL ｎ The radiance calculation method according to claim 1, characterized in that it is configured to obtain a correlation with [something].

3. An infrared camera is used to capture the infrared radiance Ld emitted from an object being imaged, using an imaging unit having a plurality of n infrared detection elements arranged on a two-dimensional plane, and an element temperature detection sensor that detects the temperature of the infrared detection elements. ｎ A device for acquiring calibration information used when calculating, When a calibration object at a predetermined temperature is imaged by the infrared camera, the temperature Ft of the infrared detection element output from the element temperature detection sensor is obtained, and the output DL from each infrared detection element is also obtained. ｎ A basic data acquisition unit that acquires the data, The temperature Ft and output DL obtained by the basic data acquisition unit are described above. ｎ Based on this, the radiance Ld emitted from the calibration object when the temperature Ft of the infrared detection element is at a predetermined temperature. ｎ and the output DL from each infrared detection element ｎ A luminance vs. output correlation acquisition unit that acquires the correlation with, The radiance Ld acquired in the luminance versus output correlation acquisition unit ｎ and output DL ｎ Based on the correlation, the approximate coefficient Aa is used to calculate the temperature correction coefficients a n, b n, and c n according to the following formula 1. ｎ Ab ｎ , Ac ｎ Ba ｎ , Bb ｎ , Bc ｎ Ca ｎ , Cb ｎ and Cc ｎ It consists of an approximation coefficient calculation unit that calculates the following, Calibration information acquisition device characterized in that the temperature correction coefficients a n, b n, and c n are used in the following formula 2 for calculating the radiance Ld n. (Equation 1) a n =Aan ・Ft 2 +Ab n ・Ft+Ac n b n =Ba n ・Ft 2 +Bb n ・Ft+Bc n c n =Can ・Ft 2 +Cb n ・Ft+Cc n (Equation 2) Ld n =a n ・DL n 2 +b n ・DL n +c n However, n is a natural number greater than or equal to 1, and is an eigenvalue corresponding to each of the infrared detection elements.

4. The temperature Ft and output DL of the infrared detection element acquired by the basic data acquisition unit. ｎ Based on this, an output-to-temperature correlation acquisition unit obtains an output-to-temperature correlation formula, Based on the output-temperature correlation formula obtained by the output-temperature correlation acquisition unit, interpolation processing is performed to determine the temperature Ft of the infrared detection element and the output DL. ｎ The system further comprises an interpolation processing unit that calculates correlation data with, The luminance versus output correlation acquisition unit acquires temperature Ft and output DL obtained by the basic data acquisition unit. ｎ , as well as the temperature Ft and output DL calculated by the interpolation processing unit. ｎ Based on the radiance Ld ｎ and the output DL ｎ The calibration information acquisition device according to claim 3, characterized in that it is configured to acquire a correlation with

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