JP4672470B2 - Infrared imaging device - Google Patents

Description

  The present invention relates to an infrared imaging device that detects the surface temperature of a road surface or a wall surface with infrared rays while moving on the road using, for example, a road or a tunnel as an imaging object, and continuously generates these infrared thermal images.

There are two types of conventional infrared imaging devices: an imaging device capable of relatively high-speed imaging and an imaging device capable of performing relatively low-speed imaging. The former is mainly used for military purposes, and only needs to be able to recognize high-temperature targets (airplanes and vehicles) from low-temperature backgrounds (sky and ground). There was no need to increase. The latter is mainly used in the private sector, and an image pickup apparatus having a higher temperature resolution than the former is commercialized by controlling a reference heat source. However, in order to control the reference heat source, it takes time to change the temperature. Patent Document 1 and Patent Document 2 disclose that image quality is improved by devising a reference heat source with the former imaging device. Patent Document 3 discloses a method for using the latter imaging device.
Japanese Patent Laying-Open No. 2005-106642 Japanese Patent Laid-Open No. 9-130679 Japanese Patent No. 3600230

  However, in the conventional infrared imaging devices described in Patent Document 1 and Patent Document 2, there is a large temperature difference between objects to be imaged, and it is not necessary to increase the temperature resolution so much. For this reason, the reference heat source for correcting the sensitivity variation of each infrared detection element is set in a wide temperature range. Patent Documents 1 and 2 disclose a configuration for dealing with a change in a photographing scene assumed in advance. However, such a configuration is not suitable for the utilization method described in Patent Document 3. That is, when the temperature resolution is increased, the image becomes noisy, and the image quality that can detect the peeling of the wall surface cannot be obtained.

  On the other hand, the infrared imaging device used in the private sector described in Patent Document 3 brings a clear image even when the temperature resolution is increased by reducing the temperature difference between the two reference heat sources by bringing the two reference heat sources closer to the object to be imaged. Shooting is possible. However, if the image is taken from a traveling vehicle as described in Patent Document 3, the reference temperature cannot be controlled in time, and a clear image cannot be obtained. Furthermore, the image has flowed in the traveling direction of the vehicle due to the low imaging speed due to the performance of the imaging sensor. Therefore, in order to photograph the peeling of the wall surface as described in Patent Document 3, it is necessary to stop the vehicle.

  The present invention has been conceived under the circumstances described above, and the sensitivity of each infrared detection element is determined according to the temperature of the imaging object without stopping the vehicle that images the inspection object with the infrared imaging device. An object of the present invention is to provide an infrared imaging device capable of correcting variations with high accuracy.

  In order to solve the above problems, the present invention takes the following technical means.

  The infrared imaging device provided by the present invention is moved relative to a continuous imaging object, and at this time, the surface temperature of the imaging object is detected by a plurality of infrared detection elements, and these infrared detections are performed. An infrared imaging device that continuously generates an infrared thermal image of the imaging object based on the output of the element, and radiates the surface temperature using the emissivity of the imaging object separately from the infrared detection element Radiation temperature measuring means for measuring as temperature, three or more heat sources variably controlled so as to have a predetermined temperature difference with respect to the radiation temperature, and individually different temperatures, and infrared rays of the imaging object are predetermined Optical imaging means for forming an image on the plurality of infrared detection elements through the optical path of the light source, and blocking infrared rays from the imaging object on the predetermined optical path, and at the same time, infrared rays of the heat source to other light By operating the optical path switching means that leads to the plurality of infrared detection elements via the optical path and the optical path switching means at a predetermined cycle, the raw pixel signals corresponding to the imaging object are obtained from the plurality of infrared detection elements. Output two frames at a time, identify the two heat sources that minimize the temperature difference between the high and low temperatures with respect to the radiation temperature, and respond to these two heat sources by switching them every other frame Control means for outputting the high-temperature pixel signal and the low-temperature pixel signal to be output from the plurality of infrared detection elements following the raw pixel signal; and a correction means for correcting the raw pixel signal based on the high-temperature pixel signal and the low-temperature pixel signal; It is characterized by having.

  As a preferred embodiment, one of the heat sources having a minimum temperature difference on the low temperature side with respect to the radiation temperature is adjusted to be equal to the radiation temperature every predetermined number of frames, and the radiation The other heat source having the smallest temperature difference on the high temperature side with respect to the temperature is adjusted so as to maintain a constant temperature difference from the radiation temperature in accordance with the temperature adjustment of the one heat source.

  As another preferred embodiment, the correction unit calculates a correction coefficient based on the high-temperature pixel signal and the low-temperature pixel signal for each infrared detection element, and a signal corresponding to the correction coefficient is used as the raw pixel signal. In addition, a corrected pixel signal is output.

  In another preferred embodiment, the optical imaging means scans infrared rays from the imaging target for each frame in a direction orthogonal to the direction of movement relative to the imaging target. A scanning mirror is included for input.

  According to such a configuration, since the plurality of heat sources are variably controlled so as to have different temperatures based on the radiation temperature of the imaging target measured based on the emissivity, for example, the road surface while moving on the road When detecting the surface temperature of the (imaging object), the temperature of each heat source can be quickly followed with respect to the surface temperature of the road surface that changes from moment to moment. That is, the raw pixel signal output from each infrared detection element is corrected based on the appropriate low-temperature pixel signal and high-temperature pixel signal obtained every other frame, and each infrared ray is in accordance with the temperature of the imaging object. Sensitivity variation of the sensing element is corrected with high accuracy. As a result, an infrared thermal image with good image quality can be obtained.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 1 to 6 show an embodiment of an infrared imaging device according to the present invention.

  As shown as an example in FIG. 1, the infrared imaging apparatus A of the present embodiment is for inspecting the wall surface of the tunnel T, and travels on the road while being mounted on the vehicle M. An infrared thermal image corresponding to the surface temperature of the wall surface is continuously generated. Although not particularly illustrated, the infrared imaging device A is connected to a GPS navigation system or a computer mounted on the vehicle. The infrared thermal image by the infrared imaging device A is stored in the hard disk device of the computer in association with the positioning information obtained from the GPS navigation system.

  As shown well in FIG. 2, the infrared imaging apparatus A includes a scanning mirror 1, objective lenses 2 and 3, a switching mirror 4, a condensing lens 5, an infrared detector 6, an amplification amplifier 7, and an A / D converter 8. , The correction circuit 9, the D / A converter 10, the radiation thermometer 20, the heat source control unit 21, as an example, the six heat sources 31 to 36, the heat source selection mirror 37, and the system control unit 40. The amplification amplifier 7 and the A / D converter 8 are provided as many as the number of infrared detection elements. Infrared rays from the wall surface of the tunnel T, which is an imaging object, pass through an optical path L0 that sequentially follows the scanning mirror 1, the objective lens 2, and the condenser lens 5 (collectively referred to as “optical imaging means”). An image is formed on the infrared detector 6. Infrared rays from the heat sources 31 to 36 form an image on the infrared detector 6 through an optical path L1 that sequentially follows the heat source selection mirror 37, the objective lens 3, the switching mirror 4, and the condenser lens 5. The radiation thermometer 20 is configured to input infrared rays from the wall surface of the tunnel T via an optical system (not shown) different from the scanning mirror 1. A signal output from the infrared detector 6 is output to a computer (not shown) through an amplifier 7, an A / D converter 8, a correction circuit 9, and a D / A converter 10. The system control unit 40 controls the scanning mirror 1, the switching mirror 4, and the heat source selection mirror 37 to operate at a predetermined timing, and exchanges various signals with the heat source control unit 21 and the correction circuit 9. .

  The scanning mirror 1 is configured to input infrared rays while repeatedly scanning within a predetermined angle range in a direction S perpendicular to the direction D in which the vehicle M travels at a constant speed. According to such a scanning mirror 1, for example, the predetermined angle range from the vicinity of the uppermost wall surface of the tunnel T to the wall surface side which is the traveling road side of the vehicle M is set as one scanning range, and during traveling at a constant speed Infrared light for one frame is input in one scan.

  The switching mirror 4 is inserted into the optical path L0 to block the infrared rays from the scanning mirror 1, and at the same time, retracts from the optical path L0 with a predetermined insertion position for guiding the infrared rays from the heat sources 31 to 36 to the infrared detector 6. Thus, a predetermined retraction position for guiding the infrared rays from the scanning mirror 1 to the infrared detector 6 can be taken, and the reciprocation is periodically performed between the insertion position and the retraction position.

  The infrared detector 6 includes, for example, 240 infrared detector elements 60 arranged in a column corresponding to the traveling direction D (sub-scanning direction) and four infrared detector elements 60 arranged in a row corresponding to the scanning direction S of the scanning mirror 1. Each infrared detection element 60 has variations in the level (sensitivity) of the signal output according to the intensity of infrared rays. For this reason, the correction circuit 9 corrects the sensitivity variation.

  The correction circuit 9 is composed of, for example, a wired logic circuit, and executes arithmetic processing at a high speed in an extremely short period. Specifically, as illustrated in FIG. 4, the correction circuit 9 takes in the raw image signal di output from each infrared detection element 60 as an input signal in accordance with the infrared rays of the imaging object. On the other hand, the correction circuit 9 obtains correction coefficients such as a gain coefficient ai and an offset coefficient bi from the high-temperature pixel signal Hi and the low-temperature pixel signal Li, and sets each of the gain coefficient ai and the offset coefficient bi to the level of the raw image signal di. A signal having a level obtained by multiplication and addition is generated. In this way, a signal after correction based on the signal levels of two points of the reference high temperature and low temperature is output as the correction pixel signal Di of each infrared detection element 60. The high temperature pixel signal Hi and the low temperature pixel signal Li will be described later.

  For example, the radiation thermometer 20 sets an emissivity composed of values specific to the concrete constituting the wall surface, and measures the surface temperature of the wall surface as the radiation temperature T ° C. based on the emissivity and infrared rays input from the wall surface. .

  The heat source control unit 21 adjusts, for example, one heat source 31 out of the six heat sources 31 to 36 to a temperature equal to the radiation temperature T ° C. measured by the radiation thermometer 20, and the other five heat sources 31 to 36. About the heat sources 32-36, it adjusts so that it may become T + 2 degreeC, T + 4 degreeC, T + 6 degreeC, T-2 degreeC, T-4 degreeC with respect to the said radiation temperature T degreeC. In particular, a heat source adjusted to a temperature equal to the radiation temperature T ° C. is referred to as a low temperature side heat source, and a heat source adjusted to a temperature of T + 2 ° C. is referred to as a high temperature side heat source.

  Each of the heat sources 31 to 36 includes a Peltier element, and is quickly adjusted to a desired temperature by a thermoelectric effect.

  The heat source selection mirror 37 is turned in the direction of the heat sources 31 to 36, and at that time, the infrared rays from the heat sources 31 to 36 are guided to the infrared detector 6 via the optical path L1.

  As an example, the system control unit 40 includes the scanning mirror 1, the switching mirror 4, the heat source selection mirror 37, the radiation thermometer 20, and the like so that signals are output from the infrared detection elements 60 at the timing shown in FIG. The operation of the heat source control unit 21 is controlled.

  Specifically, the system control unit 40 performs a control operation (field sequence f) of moving the scanning mirror 1 in the forward direction in order to capture infrared rays from the imaging target, and performs this in 75 ms, for example. At this time, the switching mirror 4 is in a position retracted from the optical path L0. During execution of such a field sequence f, the system control unit 40 causes the radiation thermometer 20 to measure the radiation temperature T ° C., and sets, for example, one heat source 31 as a low temperature side heat source to a temperature equal to the radiation temperature T ° C. To do. Of the other five heat sources 32 to 36, for example, one heat source 32 is set to a temperature of T + 2 ° C., and the other heat sources 33 to 36 are set to T + 4 ° C., T + 6 ° C., T−2 ° C., T The temperature is set to -4 ° C.

  Next to the field sequence f, the system control unit 40 turns the heat source selection mirror 37 in the direction of the low temperature side heat source and further inserts the switching mirror 4 into the optical path L0 in order to capture infrared rays from the low temperature side heat source. A control operation (low temperature reference data acquisition sequence L) is executed, and this is performed in 25 ms, for example. Thereby, from each infrared detection element 60, the signal according to the infrared rays of the low temperature side heat source is output as the low temperature pixel signal Li. During execution of such a low temperature reference data acquisition sequence L, the system control unit 40 performs control for moving the scanning mirror 1 in the backward direction and returning it to the original position.

  Further, the system controller 40 executes the field sequence f again following the low temperature reference data acquisition sequence L, and then sets the heat source selection mirror 37 in the direction of the high temperature side heat source in order to capture infrared rays from the high temperature side heat source. Then, a control operation (high temperature reference data acquisition sequence H) of inserting the switching mirror 4 into the optical path L0 is performed, and this is performed, for example, in 25 ms. Thereby, from each infrared detection element 60, the signal according to the infrared rays of the high temperature side heat source is output as the high temperature pixel signal Hi. Even during execution of such a high temperature reference data acquisition sequence H, the system control unit 40 performs control for moving the scanning mirror 1 in the backward direction and returning it to the original position. A series of execution units including the field sequence f and the low temperature reference data acquisition sequence L, and the field sequence f and the high temperature reference data acquisition sequence H are referred to as a frame. That is, the frame is repeatedly executed with a period of 100 ms. In the present embodiment, the radiation temperature T ° C. is not measured in the field sequence f executed between the low temperature reference data acquisition sequence L and the high temperature reference data acquisition sequence H. The temperature of the low-temperature heat source may be controlled to be equal to the radiation temperature T ° C. by measuring the radiation temperature T ° C. for each field sequence f.

  Next, the operation of the infrared thermal imaging apparatus A will be described with reference to the flowcharts of FIGS.

  First, the radiation temperature T ° C. is initially set in advance, and one heat source 31 is set as a low temperature side heat source so as to have a temperature equal to the radiation temperature T ° C. Of the other five heat sources 32 to 36, one heat source 32 is set as a high-temperature side heat source having a temperature of T + 2 ° C., and the other heat sources 33 to 36 are T + 4 ° C., T + 6. The temperature is set to ℃, T-2 ℃, T-4 ℃. Note that the value of the radiation temperature T ° C. that is initially set may be an empirical value or the temperature of the outside air as a temporary value.

  When the vehicle M enters the tunnel T, the scanning mirror 1 operates in the forward direction. At this time, the switching mirror 4 is in a position retracted from the optical path L0 (S1). Note that whether or not the vehicle M has entered the tunnel T is determined according to whether or not the GPS signal from the GPS navigation system has been interrupted.

  When the scanning mirror 1 operates in the forward direction, infrared rays from the wall surface of the tunnel T are input to each infrared detection element 60 via the optical path L0 by the scanning mirror 1 and the objective lens 2, and each infrared detection element 60 transmits the tunnel from the tunnel. A raw pixel signal di corresponding to the surface temperature of the wall surface of T is output (S2). These raw pixel signals di are sequentially input to the correction circuit 9.

  Further, while the scanning mirror 1 is operating in the forward direction, the radiation thermometer 20 measures a radiation temperature T ° C. of the measurement site by using a part of the wall surface of the tunnel T as an imaging surface as a measurement site (S3).

  When the present radiation temperature T ° C is equal to or greater than a predetermined difference from the set temperature of the low temperature side heat source (S4: YES), the temperature of the low temperature side heat source is controlled to be equal to the radiation temperature T ° C (S5). In addition, the other heat sources are controlled to T + 2 ° C. (high temperature side heat source), T + 4 ° C., T + 6 ° C., T−2 ° C., and T−4 ° C. (S6). For example, when the set temperature of the low temperature side heat source is 5 ° C. with respect to the current radiation temperature of 10 ° C., the heat source closest to the radiation temperature of 10 ° C. is selected and the heat source is newly set as the low temperature side heat source. The other heat sources are newly controlled at 12 ° C. (high temperature side heat source), 14 ° C., 16 ° C., 8 ° C., and 6 ° C. That is, when there is a large difference between the current radiation temperature T ° C. and the set temperature of the low temperature side heat source, the one with the smallest temperature difference is identified from the six heat sources 31 to 36, and the identified heat source is newly Set as a low-temperature heat source.

  On the other hand, when the current radiation temperature T ° C. is not equal to or higher than the set temperature of the low temperature side heat source (S4: NO), the temperatures of all the heat sources 31 to 36 including the low temperature side heat source and the high temperature side heat source are maintained as they are. . For example, when the set temperature of the low temperature side heat source is 10 ° C. with respect to the current radiation temperature of 10 ° C., the temperatures of the heat sources 31 to 36 are 10 ° C. (low temperature side heat source), 12 ° C. (high temperature side heat source), 14 ° C. , 16 ° C, 8 ° C, 6 ° C. It should be noted that the temperature of each heat source 31 to 36 is maintained as it is even when the set temperature of the low temperature side heat source is 10 ° C. and there is no significant temperature difference, for example, the radiation temperature is 10.5 ° C. Also good.

  After the above steps S4: YES to S5, S6, or S4: NO, until the scanning mirror 1 completes the forward operation, the heat source selection mirror 37 transmits the infrared rays of the low temperature side heat source to the optical path L1. (S7). Thereby, the field sequence f is completed.

  After the forward operation by the scanning mirror 1 is completed (immediately after the execution of the field sequence f), the switching mirror 4 is inserted into the optical path L0. At this time, the scanning mirror 1 is moved in the backward direction to return to the original position (S8).

  When the switching mirror 4 is inserted into the optical path L0, it is switched to the optical path L1 by the heat source selection mirror 37 and the switching mirror 4, and the infrared rays from the low temperature side heat source are input to the infrared detection elements 60 via the optical path L1 ( S9).

  Thereby, from each infrared detection element 60, the low temperature pixel signal Li according to the temperature of the low temperature side heat source is output (S10). These low-temperature pixel signals Li are sequentially input to the correction circuit 9.

  The correction circuit 9 calculates the average value Lm of the low-temperature pixel signal Li level for all the infrared detection elements 60 (S11). The average value Lm of the low-temperature pixel signal Li level as the calculation result is temporarily held in, for example, an accumulator. Thereby, the low-temperature reference data acquisition sequence ends.

  Following such a low temperature reference data acquisition sequence, the scanning mirror 1 again operates in the forward direction. Also at this time, the switching mirror 4 is in a position retracted from the optical path L0 (S12).

  When the scanning mirror 1 operates in the forward direction, infrared rays from the wall surface of the tunnel T are input to each infrared detection element 60 via the optical path L0 by the scanning mirror 1 and the objective lens 2, and each infrared detection element 60 transmits the tunnel from the tunnel. A raw pixel signal di corresponding to the surface temperature of the wall surface of T is output (S13). These raw pixel signals di are sequentially input to the correction circuit 9. For example, the raw pixel signal di obtained in the second field sequence is shifted in the traveling direction from the first time by the amount that the vehicle M is traveling at a constant speed.

  Thereafter, until the scanning mirror 1 completes the forward operation, the heat source selection mirror 37 is turned to guide the infrared rays of the high temperature side heat source to the optical path L1 (S14). Thereby, the second field sequence f is completed.

  After the forward operation by the scanning mirror 1 is completed (immediately after the execution of the second field sequence f), the switching mirror 4 is inserted into the optical path L0. Also at this time, the scanning mirror 1 is operated in the backward direction to return to the original position (S15).

  When the switching mirror 4 is inserted into the optical path L0, it is switched to the optical path L1 by the heat source selection mirror 37 and the switching mirror 4, and the infrared rays from the high-temperature side heat source are input to the infrared detection elements 60 via the optical path L1 ( S16).

  Thereby, the high temperature pixel signal Hi according to the temperature of the high temperature side heat source is output from each infrared detecting element 60 (S17). These high-temperature pixel signals Hi are sequentially input to the correction circuit 9.

  The correction circuit 9 calculates the average value Hm of the high-temperature pixel signal Hi level for all the infrared detection elements 60 (S18). The average value Hm of the high-temperature pixel signal Hi level as the calculation result is temporarily held in, for example, an accumulator. Thereby, the high temperature reference data acquisition sequence is completed.

  Thereafter, the correction circuit 9 performs correction processing on the raw pixel signal di for two frames obtained from each infrared detection element 60 (S19). In this correction processing, as shown in FIG. 4, the level of the low-temperature pixel signal Li and the high-temperature pixel signal Hi of each infrared detection element 60, the average value Lm of the low-temperature pixel signal Li level, and the high-temperature pixel signal Hi. Based on the average value Hm of the level, the gain coefficient ai and the offset coefficient bi are obtained. Thereafter, for each frame, the level of the raw pixel signal di is multiplied by the level corresponding to the gain coefficient ai, and the level corresponding to the offset coefficient bi is further added. Thereby, the correction pixel signal Di in which the sensitivity variation of each infrared detection element 60 is suppressed is obtained.

  As described above, the correction pixel signal Di for two frames is output from the correction circuit 9 every two frames (S20). Thereafter, as operations, steps S1 to S20 are repeatedly executed. That is, as the vehicle M travels at a constant speed, the correction pixel signal Di over a number of frames is sequentially output almost in real time. As a result, an infrared thermal image of the wall surface from the entrance to the exit of the tunnel T is obtained as a continuous image. can get.

  Therefore, according to the infrared imaging device A of the present embodiment, the heat sources 31 to 36 are controlled so that the temperatures of the heat sources 31 to 36 follow the radiation temperature T ° C. measured every two frames. The low-temperature side heat source and the high-temperature side heat source having the smallest possible temperature difference can be quickly selected from every other frame. As a result, the raw pixel signal di output from each infrared imaging device 60 is taken into the computer as an appropriate correction pixel signal Di corresponding to the temperature of the imaging object, and as a result, the sensitivity variation of the infrared imaging device 60 is high. An infrared thermal image corrected with accuracy can be obtained.

  The present invention is not limited to the above embodiment.

  In the above embodiment, the radiation temperature is measured every two frames and the radiation temperature is reflected on the heat source. However, for example, the radiation temperature may be measured every frame and reflected on the heat source. According to this, since each heat source is controlled so as to follow the radiation temperature more finely, the sensitivity variation of the infrared imaging element can be corrected with higher accuracy.

  The imaging object is not limited to the wall surface of the tunnel, and may be a road surface of a road, for example. Or you may use an infrared imaging device as what inspects the surface of the thing conveyed continuously on a production line.

  In the above embodiment, the temperature of the low temperature side heat source is controlled to be equal to the radiation temperature. However, the temperature of the low temperature side heat source may be controlled to be a temperature obtained by subtracting a certain value from the radiation temperature.

It is a conceptual diagram which shows one Embodiment of the infrared imaging device which concerns on this invention. It is a block diagram of the infrared imaging device shown in FIG. It is explanatory drawing for demonstrating operation | movement of the infrared imaging device shown in FIG. It is explanatory drawing for demonstrating operation | movement of the infrared imaging device shown in FIG. 3 is a flowchart for explaining an operation procedure of the infrared imaging apparatus shown in FIG. 1. 3 is a flowchart for explaining an operation procedure of the infrared imaging apparatus shown in FIG. 1.

Explanation of symbols

A Infrared imaging device L0, L1 Optical path 1 Scanning mirror (optical imaging means)
2 Objective lens (optical imaging means)
4 Switching mirror (light path switching means)
5 Condensing lens (optical imaging means)
6 Infrared detector 9 Correction circuit (correction means)
20 Radiation thermometer (radiation temperature measurement means)
31-36 Heat source 37 Heat source selection mirror (optical path switching means)
40 System control unit (control means)
60 Infrared detector

Claims (4)

In this case, the surface temperature of the imaging object is detected by a plurality of infrared detection elements, and the imaging object is detected based on the outputs of the infrared detection elements. An infrared imaging device that continuously generates infrared thermal images,
Separately from the infrared detecting element, radiation temperature measuring means for measuring the surface temperature as a radiation temperature using the emissivity of the imaging object,
Three or more heat sources that are variably controlled so as to have a predetermined temperature difference with respect to the radiation temperature and to have different temperatures individually;
Optical imaging means for imaging the infrared rays of the imaging object on the plurality of infrared detection elements via a predetermined optical path;
An optical path switching means for periodically blocking infrared rays from the imaging object on the predetermined optical path, and simultaneously guiding infrared rays of the heat source to the plurality of infrared detection elements via other optical paths;
By operating the optical path switching means at a predetermined period, the raw pixel signals corresponding to the imaging object are output frame by frame from the plurality of infrared detection elements, and during that time, Two heat sources having a minimum temperature difference on the low temperature side are specified, and the two heat sources are switched every other frame, and the corresponding high-temperature pixel signal and low-temperature pixel signal are added to the raw pixel signal after the raw pixel signal. Control means for outputting from a plurality of infrared detection elements;
Correction means for correcting the raw pixel signal based on the high temperature pixel signal and the low temperature pixel signal;
An infrared imaging device comprising:   One of the heat sources having a minimum temperature difference on the low temperature side with respect to the radiant temperature is adjusted to be equal to the radiant temperature every predetermined number of frames, and on the high temperature side with respect to the radiant temperature. 2. The infrared imaging device according to claim 1, wherein the other heat source having the smallest temperature difference is adjusted to maintain a constant temperature difference from the radiation temperature in accordance with the temperature adjustment of the one heat source.   The correction means calculates a correction coefficient based on the high-temperature pixel signal and the low-temperature pixel signal for each infrared detection element, adds a signal corresponding to the correction coefficient to the raw pixel signal, and outputs a correction pixel signal. The infrared imaging device according to claim 1 or 2.   The optical imaging means includes a scanning mirror that inputs infrared rays from the imaging object while scanning each frame in a direction orthogonal to the direction of movement relative to the imaging object. The infrared imaging device according to any one of claims 1 to 3.

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