JP2009244021A - Inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method capable of clearly distinguishing a defect detection signal from a noise signal contained in surface temperature data and positively detecting defects (cracks, etc.) of an inspection object regardless of the surface state of the inspection object. <P>SOLUTION: For example, a first scan (forward scan) is performed to obtain first surface temperature data before heating by measuring the surface temperature of the inspection object with an infrared detection device (a detection element) without heating the surface of the inspection object with a laser, and a second scan (backward scan B) is performed to obtain second surface temperature data D2 after heating by measuring the surface temperature of the inspection object with the infrared detection device (the detection element) by heating the surface of the inspection object with a laser. Third surface temperature data D3 are obtained by subtracting the first surface temperature data D1 from the second surface temperature data D2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inspection method for inspecting whether or not a defect such as a crack has occurred near the surface of an inspection object using an infrared detection means and a heating means.

  In order to evaluate the soundness of inspection objects such as equipment, by inspection methods such as dye penetration testing (PT), magnetic particle testing (MT), eddy current testing (ECT), ultrasonic testing (UT), etc. The inspection object is inspected. However, since these inspection methods are methods in which an inspection object is in contact with each other, depending on the surface state (temperature, roughness, shape) of the inspection object, the inspection object may not be applied. It can be difficult.

  On the other hand, a method for detecting defects (such as cracks) near the surface of an inspection object by measuring the surface temperature of the inspection object with an infrared detection device (detection element) or the like is also widely known. In addition, when measuring the surface temperature of an inspection object with an infrared detection device (detection element), a method for improving detection performance by heating or cooling the surface of the inspection object is also widely known. Lasers, lamps, heaters, and the like are known as heating means.

  There is an inspection apparatus called a photothermal camera that can perform defect inspection on the surface of an inspection object in a non-contact manner by using a laser as a heating means. In this inspection apparatus, an infrared detection device (detection element) and a laser beam scan the surface of the inspection object. At this time, the surface of the inspection object is heated by irradiating the surface of the inspection object, and the surface temperature of the inspection object heated by the laser (radiant heat from the surface) is detected by the infrared detector (detection element). ). Thus, surface temperature data (temperature distribution data) of the inspection object is obtained, and defects (such as cracks) near the surface of the inspection object can be detected based on the surface temperature data.

  Further, by reciprocating the scanning of the infrared detection device (detection element) and the laser (that is, by performing forward scanning and backward scanning), the first surface temperature data as the forward scanning data and the backward scanning data are used. After obtaining the second surface temperature data, the first surface temperature data is subtracted from the second surface temperature data to obtain the third surface temperature data, whereby the surface deposit on the inspection object is obtained. There has also been a contrivance to reduce noise signals caused by noise factors such as dirt and dirt (see FIGS. 3A and 4A: details will be described later).

JP-A-4-331360

  However, in the conventional subtracting inspection method, the noise signal cannot be sufficiently reduced depending on the surface state of the inspection object (roughness, dirt, adhered matter, wetness, etc.), and the defect detection signal and the noise signal can be reduced. In some cases, it was difficult to clearly distinguish them. In this case, even if there is a defect (such as a crack) near the surface of the inspection object, it is difficult to reliably detect the defect.

  Therefore, in view of the above circumstances, the present invention can clearly distinguish between a defect detection signal and a noise signal included in the surface temperature data regardless of the surface state of the inspection object, and reliably detect defects (such as cracks). It is an object to provide an inspection method that can be detected.

The inspection method of the first invention that solves the above problem is an inspection method that inspects the vicinity of the surface of the inspection object by scanning the surface of the inspection object using an infrared detection means and a heating means.
A first scan that obtains first surface temperature data before heating by measuring the surface temperature of the inspection object with the infrared detection means without heating the surface of the inspection object with the heating means;
While the surface of the inspection object is heated by the heating means, the surface temperature of the inspection object is measured by the infrared detection means, and a second scan is performed to obtain second surface temperature data after heating. ,
The third surface temperature data is obtained by subtracting the first surface temperature data from the second surface temperature data.

Further, the inspection method of the second invention is an inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using an infrared detection means and a heating means.
Without heating the surface of the object to be inspected by the heating means, the surface temperature of the object to be inspected is measured by the infrared detecting means, and a first scan is performed to obtain first surface temperature data before heating. ,
While changing the output of the heating means according to the first surface temperature data, the surface temperature of the inspection object is measured by the infrared detection means while the surface of the inspection object is heated by the heating means. Then, a second scan for obtaining second surface temperature data after heating is performed.

The inspection method of the third invention is an inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using an infrared detection means and a heating means.
A first scan that obtains first surface temperature data by measuring the surface temperature of the inspection object with the infrared detection means while heating the surface of the inspection object with the heating means;
While heating the surface of the inspection object with the heating means, the surface temperature of the inspection object is measured with the infrared detection means, and a second scan to obtain second surface temperature data is performed,
The third surface temperature data is obtained by multiplying the first surface temperature data and the second surface temperature data.

The inspection method of the fourth invention is the inspection method of the third invention,
After performing the first scan and the second scan,
In the first surface temperature data, data larger than the first reference value is positive, data smaller than the first reference value is negative, and in the second surface temperature data, the data is larger than the second reference value. Large data is positive, data smaller than the second reference value is negative,
Then, the third surface temperature data is obtained by performing the multiplication.

The inspection method of the fifth invention is the inspection method of the first, third or fourth invention,
At least one marker having a radiation rate different from that of the inspection object is provided on the surface of the inspection object, and the first scan and the second are performed with respect to the surface of the inspection object including a region where the marker is provided. And scanning
And, when there is a positional deviation between the position of the marker detection signal included in the first surface temperature data and the position of the marker detection signal included in the second surface temperature data, After correcting the position of the first surface temperature data or the second surface temperature data based on this displacement,
The third surface temperature data is obtained by performing the subtraction or the multiplication.

The inspection method of the sixth invention is an inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using an infrared detection means and a heating means.
Providing at least one marker having a different emissivity from the inspection object on the surface of the inspection object;
While heating the surface of the inspection object including the area where the marker is provided by the heating means, the surface temperature of the inspection object is measured by the infrared detection means to obtain first surface temperature data. 1 scan,
While heating the surface of the inspection object including the area where the marker is provided by the heating means, the surface temperature of the inspection object is measured by the infrared detection means to obtain second surface temperature data. 2 scans,
And, when there is a positional deviation between the position of the marker detection signal included in the first surface temperature data and the position of the marker detection signal included in the second surface temperature data, Correcting the position of the first surface temperature data or the second surface temperature data based on this positional deviation,
In the first surface temperature data, data larger than the first reference value is positive, data smaller than the first reference value is negative, and in the second surface temperature data, the data is larger than the second reference value. Large data is positive and data smaller than the second reference value is negative.
The third surface temperature data is obtained by subtracting the first surface temperature data from the second surface temperature data.

The inspection method of the seventh invention is the inspection method of the fifth or sixth invention,
A plurality of the markers are provided along the scanning direction.

  According to the inspection method of the first invention, in the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means, the heating means Without heating the surface of the inspection object, by measuring the surface temperature of the inspection object with the infrared detection means, to obtain first surface temperature data before heating, and with the heating means While the surface of the inspection object is heated, the surface temperature of the inspection object is measured by the infrared detection means, and second scanning is performed to obtain second surface temperature data after heating. Since the third surface temperature data is obtained by subtracting the first surface temperature data from the surface temperature data, a defect detection signal and a noise signal are included in the second surface temperature data. Even the third table In the temperature data, the noise signal is sufficiently reduced by the subtraction, it is clear distinction between the defect detection signal and the noise signal. Therefore, for example, by comparing the predetermined threshold value with the third surface temperature data and determining whether the third surface temperature data includes a signal equal to or higher than the threshold value, the third surface temperature is surely determined. It can be determined that the data includes a defect detection signal caused by a defect (such as a crack). That is, a defect (such as a crack) can be reliably detected.

  According to the inspection method of the second invention, in the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means, the heating means Without heating the surface of the inspection object, the surface temperature of the inspection object is measured by the infrared detection means, and a first scan for obtaining first surface temperature data before heating is performed. The surface temperature of the inspection object is measured by the infrared detection means while heating the surface of the inspection object by the heating means while changing the output of the heating means according to the surface temperature data of the heating, and heating Since it is characterized by performing a second scan to obtain second surface temperature data later, even if there are defects (such as cracks) on the surface of the inspection object and noise factors such as deposits and dirt, In the second surface temperature data, Signal is sufficiently reduced, to clarify the distinction between the defect detection signal and the noise signal. Accordingly, for example, by comparing the predetermined threshold value with the second surface temperature data and determining whether or not the second surface temperature data includes a signal equal to or higher than the threshold value, the second surface temperature is surely determined. It can be determined that the data includes a defect detection signal caused by a defect (such as a crack). That is, a defect (such as a crack) can be reliably detected.

  According to the inspection method of the third invention, in the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means, the heating means While the surface of the inspection object is heated, the surface temperature of the inspection object is measured by the infrared detection means to obtain first surface temperature data, and the inspection object is detected by the heating means. The surface temperature of the object to be inspected is measured by the infrared detection means while the surface of the object is heated, and a second scan is performed to obtain second surface temperature data, and the first surface temperature data, Since the third surface temperature data is obtained by multiplying the second surface temperature data, the first surface temperature data and the second surface temperature data include a defect detection signal and a noise signal. Even if In the third surface temperature data, a defect detection signal obtained as a result of multiplication of relatively large defect detection signals is much larger than a noise signal obtained as a result of multiplication of relatively small noise signals. Become. For this reason, in the third surface temperature data, the distinction between the defect detection signal and the noise signal becomes clear. Therefore, for example, by comparing the predetermined threshold value with the third surface temperature data and determining whether the third surface temperature data includes a signal equal to or higher than the threshold value, the third surface temperature is surely determined. It can be determined that the data includes a defect detection signal caused by a defect (such as a crack). That is, a defect (such as a crack) can be reliably detected.

  According to the inspection method of the fourth invention, in the inspection method of the third invention, after performing the first scan and the second scan, the first surface temperature data is more than the first reference value. Large data is positive, data smaller than the first reference value is negative, and in the second surface temperature data, data larger than the second reference value is positive, and data smaller than the second reference value is Since the third surface temperature data is obtained by performing negative multiplication and then performing the multiplication, the third surface temperature data does not detect defects regardless of the depth of defects (cracks, etc.). There is a significant difference between the magnitude of the signal and the noise signal (when the crack is shallow), or the defect detection signal and the noise signal are divided into positive and negative, and the distinction between the defect detection signal and the noise signal becomes clear. Therefore, for example, by comparing the predetermined threshold value with the third surface temperature data and determining whether the third surface temperature data includes a signal equal to or higher than the threshold value, or the predetermined threshold value and the third surface temperature data. By comparing the surface temperature data 6 and the third surface temperature data to determine whether or not the signal below the threshold is included, it is ensured that the third surface temperature data is caused by a defect (such as a crack). It can be determined that a defect detection signal to be included is included. That is, a defect (such as a crack) can be reliably detected.

  According to the inspection method of the fifth invention, in the inspection method of the first, third or fourth invention, at least one marker having a radiation rate different from that of the inspection object is provided on the surface of the inspection object, Performing the first scan and the second scan on the surface of the inspection object including the provided region, and a position of a marker detection signal included in the first surface temperature data; If there is a positional deviation from the position of the marker detection signal included in the second surface temperature data, the first surface temperature data or the second surface temperature is based on the positional deviation. Since the third surface temperature data is obtained by performing the subtraction or the multiplication after correcting the position of the data, the first surface temperature data and the second surface temperature data can be obtained by shifting the surface inspection apparatus. Table of Even if the position shift on the temperature data occurs, and the positional deviation is corrected, it is possible to more reliably the subtraction or the multiplication is performed. Therefore, since the distinction between the defect detection signal and the noise signal in the third surface temperature data can be clarified more reliably, defects (cracks and the like) can be detected more reliably.

  According to the inspection method of the sixth aspect of the invention, in the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using infrared detection means and heating means, the inspection object The surface of the inspection object is provided with at least one marker having a radiation rate different from that of the inspection object on the surface, and the surface of the inspection object including the region where the marker is provided is heated by the heating means. While measuring the temperature with the infrared detecting means and obtaining the first surface temperature data, and heating the surface of the inspection object including the region where the marker is provided with the heating means, The surface temperature of the object to be inspected is measured by the infrared detecting means, and the second scan for obtaining the second surface temperature data is performed, and the marker detection signal included in the first surface temperature data Place And the position of the marker detection signal included in the second surface temperature data, the first surface temperature data or the second surface based on the position deviation The position of the temperature data is corrected, in the first surface temperature data, data larger than the first reference value is positive, data smaller than the first reference value is negative, and the second surface temperature data By subtracting the first surface temperature data from the second surface temperature data, assuming that data larger than the second reference value is positive and data smaller than the second reference value is negative, Therefore, even if the first surface temperature data and the second surface temperature data are misaligned due to misalignment of the surface inspection apparatus, the misalignment is corrected. ,Than Since indeed the subtraction is performed, it can be clarified more reliably distinguish the defect detection signal and a noise signal in the third surface temperature data. Therefore, it is possible to detect a defect (such as a crack) more reliably. Therefore, since the distinction between the defect detection signal and the noise signal in the third surface temperature data can be clarified more reliably, defects (cracks and the like) can be detected more reliably.

  According to the inspection method of the seventh aspect of the invention, in the inspection method of the fifth or sixth aspect of the invention, a plurality of the markers are provided along the scanning direction. In this case, the positional deviation caused by the deviation occurs in a part of the marker detection signal. Therefore, based on the positional deviation of the part of the marker detection signal, the first surface temperature data or the second surface temperature data The position can be corrected.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 is a diagram showing an outline of an inspection apparatus for carrying out an inspection method according to Embodiment 1 of the present invention, FIG. 2 is an explanatory diagram of the inspection method, and FIG. An image diagram is shown, and (b) shows a waveform diagram showing signal processing contents.

  The surface inspection apparatus shown in FIG. 1 is an apparatus called a photothermal camera, and includes an infrared detection device (detection element) 1 as an infrared detection means, a laser 2 as a heating means, a signal processing device 3, and an actuator (not shown). It has. The hardware configuration itself of this surface inspection apparatus is the same as the conventional one. The infrared detection device (detection element) 1 and the laser 2 are arranged in contact with the inspection object 4 such as equipment in a non-contact manner, and are driven by an actuator to reciprocate as indicated by arrows in FIG. The surface 4a of the inspection object 4 can be reciprocally scanned (forward scanning F and backward scanning B are performed). FIG. 1 shows a state in which a defect (such as a crack) 6 is generated on the surface 4a of the inspection object 4. FIG. When performing reciprocating scanning (forward scanning F, backward scanning B), the infrared detection device (detection element) 1 is not moved linearly as shown in the illustrated example, but the infrared detection device (detection element) 1 and the laser 2 are not moved linearly. The laser 2 may be rotated around the rotation axis (that is, the head is swung).

  The laser 2 emits a laser beam 2a during scanning, and the surface 4a is heated by irradiating the surface a of the inspection object 4 with the laser beam 2a via the reflection mirrors 5a and 5b. During scanning, the infrared detecting device (detecting element) 1 measures the temperature of the surface 4a of the inspection object 4 (radiant heat from the surface 4a) to obtain surface temperature data (surface temperature distribution data). The signal processing device 3 processes the surface temperature data obtained by the infrared detection device (detection element) 1 so that the defect detection signal and the noise signal included in the surface temperature data can be clearly distinguished, Defect 6 is detected.

  This inspection method will be described in detail with reference to FIG. As shown in FIG. 2A and FIG. 2B, the forward scanning F that is the first scanning is performed to obtain the first surface temperature data D1 that is the pre-heating data, and then the second scanning. Reverse scanning B is performed to obtain second surface temperature data D2 that is post-heating data. That is, in the forward scanning F, the surface 4a of the inspection object 4 is not heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the surface 4a of the inspection object 4 before the heating is heated. The temperature (radiant heat from the surface 4a) is measured by the infrared detection device (detection element) 1 to obtain first surface temperature data D1 (surface temperature distribution data) before heating. In the backward scanning B, the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the temperature of the heated surface 4a of the inspection object 4 (radiant heat from the surface 4a). Is measured by the infrared detection device (detection element) 1 to obtain second surface temperature data D2 (surface temperature distribution data) after heating.

  Even if there are noise factors such as surface deposits and dirt or defects 6 on the surface 4a of the inspection object 4, the first surface temperature data D1 before heating does not show a defect detection signal due to the defects 6, Only the noise signal ND1 resulting from the noise factor is included. On the other hand, when there are noise factors such as surface deposits and defects 6 on the surface 4a of the inspection object 4, the first surface temperature data D2 after heating includes a defect detection signal KD2 due to the defects 6 and noise. The noise signal ND2 resulting from the factor is included.

  The reason why the defect detection signal KD2 is obtained is as follows. That is, when the surface 4a of the inspection object 4 is heated by the laser 2 in the backward scanning B in FIG. 1, heat conduction usually occurs on the surface 4a of the inspection object 4, but the heat conduction is cut off at the defect 6 portion. Therefore, heat is accumulated at the edge 8 of the defect 6 and the temperature (radiant heat) of the edge 8 is increased. Therefore, the defect detection signal KD2 is obtained by measuring the temperature of the edge 8 of the defect 6 by the infrared detection device (detection element) 1. Similarly, in the forward scanning F of FIG. 1, when the surface 4 a of the inspection object 4 is heated by the laser 2, the heat conduction is cut off at the defect 6 portion, so that the edge 7 of the defect 6 is formed. Since heat accumulates and the temperature (radiant heat) of the edge 7 increases, the temperature of the edge 7 of the defect 6 is measured by the infrared detection device (detection element) 1 to obtain a defect detection signal.

  And in the signal processing apparatus 3, the 3rd surface temperature data D3 is obtained by subtracting the 1st surface temperature data D1 before a heating from the 2nd surface temperature data D2 after a heating. In the third surface temperature data D3, since the noise signal ND3 is sufficiently reduced by the subtraction, the distinction between the defect detection signal KD3 corresponding to the defect detection signal KD2 and the noise signal ND3 becomes clear. Therefore, for example, by comparing the predetermined threshold value S1 with the third surface temperature data D3 and determining whether or not the third surface temperature data D3 includes a signal equal to or higher than the threshold value S1, the third surface temperature data D3 can be reliably detected. It can be determined that the surface temperature data D3 includes the defect detection signal KD3 caused by the defect 6. That is, the defect 6 can be reliably detected.

  Although not shown, instead of the subtraction method as described above, in the second scan (backward scan B), the first surface temperature data D1 obtained by the first scan (forward scan F) is used. Accordingly, the output of the laser 1 may be adjusted by the laser output adjusting means. In this case, in the second scanning (backward scanning B), the inspection is performed while heating the surface 4a of the inspection object 4 with the laser 2 while changing the output of the laser 2 according to the first surface temperature data D1. The temperature of the surface 4a of the object 4 is measured by the infrared detection device (detection element) 1 to obtain second surface temperature data after heating. Specifically, in accordance with the first surface temperature data D1, the output of the laser 2 is reduced at a scanning position with a high temperature (position on the surface 4a of the inspection object 4), and the laser 2 is scanned at a scanning position with a low temperature. Increase output.

  Even in the second surface temperature data in this case, the noise signal is sufficiently reduced as in the case of the third surface temperature data D3 obtained by the subtraction method, so that the distinction between the defect detection signal and the noise signal becomes clear. . Accordingly, in this case as well, for example, a predetermined threshold value is compared with the second surface temperature data in the same manner as described above, and it is determined whether the second surface temperature data includes a signal equal to or higher than the threshold value. It can be reliably determined that the second surface temperature data includes the defect detection signal resulting from the defect 6. That is, the defect 6 can be reliably detected.

  As described above, according to the inspection method of the first embodiment, the inspection object is scanned by scanning the surface a of the inspection object 4 using the infrared detection device (detection element) 1 and the laser 2. In the inspection method for inspecting the vicinity of the surface 4a of 4 (whether or not there is a defect 6 (crack or the like) in the vicinity of the surface 4a), the laser 6 does not heat the surface 4a of the inspection object 4 and the infrared detection device (detection) The element 1) measures the surface temperature of the inspection object 4 to obtain the first surface temperature data D1 before heating, and the laser 2 scans the surface 4a of the inspection object 4 with the laser 2. While heating, the surface temperature of the inspection object 4 is measured by the infrared detection device (detection element) 1 and a second scan (reverse scan B) for obtaining the second surface temperature data D2 after heating is performed. From the second surface temperature data D2, the first surface temperature data Since the third surface temperature data D3 is obtained by subtracting 1, even if the second surface temperature data D2 includes the defect detection signal KD2 and the noise signal ND2, the third surface temperature data D3 is obtained. In the temperature data D3, the noise signal ND3 is sufficiently reduced by the subtraction, and the distinction between the defect detection signal KD3 and the noise signal ND3 becomes clear. For this reason, it can be determined that the defect detection signal KD3 resulting from the defect 6 is included in the third surface temperature data D3, and the defect 6 can be detected reliably.

  According to another inspection method of the first embodiment, the inspection object 4 is scanned by scanning the surface 4 a of the inspection object 4 using the infrared detection device (detection element) 1 and the laser 2. In an inspection method for inspecting the vicinity of the surface 4a (whether or not a defect 6 (crack or the like is generated in the vicinity of the surface 4a)), the laser 2 does not heat the surface 4a of the inspection object 4 and the infrared detection device (detection element) 1) The surface temperature of the inspection object 4 is measured at 1, and a first scan (forward scan F) for obtaining the first surface temperature data D1 before heating is performed, and according to the first surface temperature data D2 While changing the output of the laser 2 and heating the surface a of the inspection object 4 with the laser 2, the surface temperature of the inspection object 4 is measured by the infrared detection device (detection element) 1, and the second temperature after the heating is measured. 2nd scan to obtain surface temperature data of 2 (reverse scan) ), Even if there are defects 6 (cracks) on the surface 4a of the inspection object 4 and noise factors such as deposits and dirt, the second surface temperature data has no noise signal. Sufficiently reduced, the distinction between the defect detection signal and the noise signal becomes clear. For this reason, it can be determined that the defect detection signal resulting from the defect 6 is included in the second surface temperature data with certainty, and the defect 6 can be reliably detected.

<Embodiment 2>
FIG. 3A is an explanatory diagram of a conventional inspection method in which defects (cracks and the like) are relatively shallow, and FIG. 3B is an inspection method according to Embodiment 2 of the present invention, in which defects ( It is explanatory drawing when a crack etc. are comparatively shallow. FIG. 4A is an explanatory diagram of a conventional inspection method when defects (cracks, etc.) are relatively deep, and FIG. 4B is an inspection method according to Embodiment 2 of the present invention. It is explanatory drawing when a defect (crack etc.) is comparatively deep.

  In the second embodiment as well, the configuration of the surface inspection apparatus is the same as that in the first embodiment, so FIG. 1 will be referred to and illustration and detailed description thereof will be omitted here.

  First, based on FIG. 3A and FIG. 4A, a case where a conventional inspection method is performed using the surface inspection apparatus shown in FIG. 1 will be described.

  The case where the defect 6 is relatively shallow will be described. As shown in FIG. 3A, after the forward scanning F which is the first scanning is performed and the first surface temperature data D11 which is the forward scanning data is obtained. Then, the backward scanning B as the second scanning is performed to obtain the second surface temperature data D12 as the backward scanning data. That is, in the forward scanning F, while the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a) Radiant heat) is measured by the infrared detecting device (detecting element) 1 to obtain first surface temperature data D11 (surface temperature distribution data) after heating. Similarly, in reverse scanning B, the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a). Radiant heat) is measured by the infrared detecting device (detecting element) 1 to obtain second surface temperature data D12 (surface temperature distribution data) after heating.

  When the surface 4a of the inspection object 4 has noise factors such as surface deposits and dirt and the defect 6, the first surface temperature data D11 includes the defect detection signal KD11 caused by the defect 6 and the noise factor. Therefore, the second surface temperature data D12 also includes the defect detection signal KD12 caused by the defect 6 and the noise signal ND12 caused by the noise factor.

  In the signal processing device 3, the third surface temperature data D13 is obtained by subtracting the second surface temperature data D12 from the first surface temperature data D11. In the third surface temperature data D13, the noise signal ND13 is sufficiently reduced by the subtraction, while some defect detection signals KD13 remain. This is because the generation position of the noise signal ND11 at the time of forward scanning and the generation position of the noise signal ND12 at the time of backward scanning coincide with each other, while the position of the defect detection signal KD11 at the time of forward scanning and the generation position of KD12 at the time of backward scanning This is because the heat storage position (edges 7 and 8) is different between forward scanning and backward scanning, so that there is a slight shift. However, even if such subtraction is performed, the noise signal ND13 may not be sufficiently reduced depending on the surface state of the inspection object 4 as described above, and the defect detection signal KD13 is also small, so the defect detection signal KD13. It may be difficult to clearly distinguish the noise signal ND13 from the noise signal ND13.

  The case where the defect 6 is relatively deep will be described. As shown in FIG. 4A, after the forward scanning F which is the first scanning is performed, the first surface temperature data D21 which is the forward scanning data is obtained. Then, the backward scanning B as the second scanning is performed to obtain the second surface temperature data D22 as the backward scanning data. That is, in the forward scanning F, while the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a) Radiant heat) is measured by the infrared detector (detection element) 1 to obtain first surface temperature data D21 (surface temperature distribution data) after heating. Similarly, in reverse scanning B, the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a). Radiant heat) is measured by the infrared detection device (detection element) 1 to obtain second surface temperature data D22 (surface temperature distribution data) after heating.

  When the surface 4a of the inspection object 4 has noise factors such as surface deposits and dirt and the defect 6, the first surface temperature data D21 includes the defect detection signal KD21 resulting from the defect 6 and the noise factor. Therefore, the second surface temperature data D22 also includes the defect detection signal KD22 caused by the defect 6 and the noise signal ND22 caused by the noise factor. When the defect 6 is deep, the defect detection signal KD21 is a signal that increases greatly on the upstream side in the forward scanning direction and decreases greatly on the downstream side, and the defect detection signal KD22 increases greatly on the upstream side in the backward scanning direction. However, the signal decreases greatly on the downstream side. For this reason, the defect detection signal KD21 at the time of forward scanning and the defect detection signal KD22 at the time of backward scanning have an inverse relationship between the increase position and the decrease position. On the other hand, the noise signal ND21 at the time of forward scanning and the noise signal ND22 at the time of backward scanning both increase, and the generation positions thereof also coincide.

  In the signal processing device 3, in the first surface temperature data D21, data larger than the predetermined first reference value K1 is positive, data smaller than the first reference value K1 is negative, and second data In the surface temperature data D22, data larger than the predetermined second reference value K2 is positive, and data smaller than the second reference value K2 is negative, and then the second surface temperature is determined from the first surface temperature data D21. The third surface temperature data D23 is obtained by subtracting the data D22. The reference values K1 and K2 are the average value of the surface temperature of the inspection object 4 at the time of forward scanning and the average value of the surface temperature of the inspection object 4 at the time of backward scanning, and are, for example, the first surface temperature data D21. The average value and the average value of the second surface temperature data D22 may be used. The average value of the surface temperature of the inspection object 4 at the time of forward scanning estimated by conducting experiments and analysis in advance and the inspection at the time of backward scanning. The average value of the surface temperature of the target object 4 may be sufficient.

  In the third surface temperature data D13, the noise signal ND23 is sufficiently reduced by the subtraction, but a large defect detection signal KD23 remains, so that the distinction between the defect detection signal KD23 and the noise signal ND23 becomes clear. Therefore, for example, by comparing the predetermined threshold value with the third surface temperature data D23 and determining whether or not the third surface temperature data D23 includes a signal equal to or higher than the threshold value, the third surface temperature data is determined. It can be determined that the defect detection signal KD23 caused by the defect 6 is included in D23. However, even if such subtraction is performed, the noise signal ND23 may not be sufficiently reduced depending on the surface state of the inspection object 4 as described above, and it is difficult to clearly distinguish the defect detection signal KD23 from the noise signal ND23. There was a case.

  Next, based on FIGS. 3B and 4B, a case where the inspection method of the second embodiment is performed using the surface inspection apparatus shown in FIG. 1 will be described.

  The case where the defect 6 is relatively shallow will be described. As shown in FIG. 3B, after the forward scanning F that is the first scanning is performed and the first surface temperature data D14 that is the forward scanning data is obtained. Then, the backward scanning B as the second scanning is performed to obtain the second surface temperature data D15 as the backward scanning data. That is, in the forward scanning F, while the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a) Radiant heat) is measured by the infrared detection device (detection element) 1 to obtain first surface temperature data D14 (surface temperature distribution data) after heating. Similarly, in reverse scanning B, the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a). Radiant heat) is measured by the infrared detection device (detection element) 1 to obtain second surface temperature data D15 (surface temperature distribution data) after heating.

  When there are noise factors such as surface deposits and defects 6 on the surface 4a of the inspection object 4, the first surface temperature data D14 includes a defect detection signal KD14 caused by the defect 6 and noise caused by the noise factor. The signal ND14 is included, and the second surface temperature data D15 also includes the defect detection signal KD15 attributed to the defect 6 and the noise signal ND15 attributed to the noise factor.

  The signal processing device 3 multiplies the first surface temperature data D14 and the second surface temperature data D15 to obtain third surface temperature data D16. Since the defect detection signals KD14 and 15 caused by the edges 7 and 8 of the defect 6 having a large heat storage amount have a larger value than the noise signals ND14 and 15, the third surface temperature data D16 is relatively Compared with the noise signal ND16 obtained as a result of multiplication between the small noise signals ND14 and 16, the defect detection signal KD16 obtained as a result of multiplication between the relatively large defect detection signals KD14 and 16 has a much larger value. Therefore, in the third surface temperature data D16, the distinction between the defect detection signal KD16 and the noise signal ND16 becomes clear. Therefore, for example, by comparing the predetermined threshold value S2 with the third surface temperature data D16 and determining whether or not the third surface temperature data D16 includes a signal equal to or greater than the threshold value S2, the third surface temperature data D16 is reliably determined. It can be determined that the surface temperature data D16 includes the defect detection signal KD16 caused by the defect 6. That is, the defect 6 can be reliably detected.

  The case where the defect 6 is relatively deep will be described. As shown in FIG. 4B, after the forward scanning F which is the first scanning is performed, the first surface temperature data D24 which is the forward scanning data is obtained. Then, the backward scanning B as the second scanning is performed to obtain the second surface temperature data D25 as the backward scanning data. That is, in the forward scanning F, while the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a) Radiant heat) is measured by the infrared detecting device (detecting element) 1 to obtain first surface temperature data D24 (surface temperature distribution data) after heating. Similarly, in reverse scanning B, the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a). Radiant heat) is measured by the infrared detection device (detection element) 1 to obtain second surface temperature data D25 (surface temperature distribution data) after heating.

  When the surface 4a of the inspection object 4 has noise factors such as surface deposits and dirt and the defect 6, the first surface temperature data D24 includes the defect detection signal KD24 resulting from the defect 6 and the noise factor. Therefore, the second surface temperature data D25 also includes the defect detection signal KD25 caused by the defect 6 and the noise signal ND25 caused by the noise factor. As described above, when the defect 6 is deep, the defect detection signal KD24 greatly increases on the upstream side in the forward scanning direction and decreases greatly on the downstream side, and the defect detection signal KD25 increases significantly on the upstream side in the backward scanning direction. However, the signal decreases greatly on the downstream side. For this reason, the defect detection signal KD24 at the time of forward scanning and the defect detection signal KD25 at the time of backward scanning have an inverse relationship between the increase position and the decrease position. On the other hand, the noise signal ND24 at the time of forward scanning and the noise signal ND25 at the time of backward scanning both increase, and the generation positions thereof also coincide.

  In the signal processing device 3, in the first surface temperature data D24, data larger than the predetermined first reference value K3 is positive, data smaller than the first reference value K3 is negative, and second data In the surface temperature data D25, data larger than the predetermined second reference value K4 is positive, and data smaller than the second reference value K4 is negative. Then, the first surface temperature data D24 and the second surface temperature The third surface temperature data D26 is obtained by multiplying the data D25. The reference values K3 and K4 are the average value of the surface temperature of the inspection object 4 during forward scanning and the average value of the surface temperature of the inspection object 4 during backward scanning, for example, the first surface temperature data D24. The average value and the average value of the second surface temperature data D25 may be used, and the average value of the surface temperature of the inspection object during forward scanning estimated by conducting experiments and analysis in advance and the inspection during backward scanning. It may be an average value of the surface temperature of the object.

  In the third surface temperature data D13, the noise signal ND26 becomes a positive value as a result of multiplication of the positive noise signals ND24 and 25, while the defect detection signal KD26 is a positive part of the defect detection signal KD24 and defect detection. As a result of multiplication of the negative part of the signal KD25 and multiplication of the negative part of the defect detection signal KD24 and the positive part of the defect detection signal KD25, a large negative value is obtained. Therefore, in the third surface temperature data D26, the distinction between the defect detection signal KD26 and the noise signal ND26 becomes clear. Therefore, for example, by comparing the predetermined threshold value S3 with the third surface temperature data D26 and determining whether or not the third surface temperature data D26 includes a signal equal to or lower than the threshold value S3, the third surface temperature is surely determined. It can be determined that the surface temperature data D26 includes the defect detection signal KD26 caused by the defect 6. That is, the defect 6 can be reliably detected.

  Even when the defect 6 is relatively shallow, data larger than a predetermined first reference value in the first surface temperature data D14 is positive and first as in the case where the defect 6 is relatively deep. After making the data smaller than the reference value negative, and making the data larger than the predetermined second reference value positive in the second surface temperature data D15, and making the data smaller than the second reference value negative, It is desirable to obtain the third surface temperature data D16 by multiplying the first surface temperature data D14 and the second surface temperature data D15. The first reference value and the second reference value are the average value of the surface temperature of the inspection object 4 during forward scanning and the average value of the surface temperature of the inspection object 4 during backward scanning. The average value of the surface temperature data D14 and the average value of the second surface temperature data D15 may be used. The average value of the surface temperature of the object to be inspected at the time of forward scanning estimated by conducting experiments and analyzes in advance and the reverse It may be an average value of the surface temperature of the inspection object during scanning.

  As described above, according to the inspection method of the second embodiment, the inspection object is scanned by scanning the surface 4a of the inspection object 4 using the infrared detection device (detection element) 1 and the laser 2. In the inspection method for inspecting the vicinity of the surface 4a of 4 (whether or not a defect 6 (crack or the like is generated in the vicinity of the surface 4a)), the inspection object 4 is heated while heating the surface 4a of the inspection object 4 with the laser 2. The surface temperature of the test object 4 is measured by the infrared detection device (detection element) 1 to obtain the first surface temperature data D14, and the surface 4a of the inspection object 4 is heated by the laser 2 However, the surface temperature of the inspection object 4 is measured by the infrared detection device (detection element) 1 and the second scanning (reverse scanning B) for obtaining the second surface temperature data D15 is performed. Temperature data D1 and second surface temperature data D1 And the third surface temperature data D16 is obtained by multiplying the first surface temperature data D14 and the second surface temperature data D15 with the defect detection signals KD14 and KD15 and the noise signal ND14, Even if ND15 is included, in the third surface temperature data D16, the relatively large defect detection signals KD14 and KD15 are compared with each other in comparison with the noise signal ND16 obtained as a result of multiplication between the relatively small noise signals ND14 and ND15. The defect detection signal KD16 obtained as the multiplication result has a much larger value, and the distinction between the defect detection signal KD16 and the noise signal ND16 becomes clear. For this reason, it can be determined that the defect detection signal KD16 resulting from the defect 6 is included in the third surface temperature data, and the defect 6 can be reliably detected.

  Further, according to another inspection method of the second embodiment, the inspection object 4 is scanned by scanning the surface 4 a of the inspection object 4 using the infrared detection device (detection element) 1 and the laser 2. In the inspection method for inspecting whether or not a defect 6 (crack or the like is generated in the vicinity of the surface 4a), the surface 4a of the inspection object 4 is heated while heating the surface 4a of the inspection object 4 with the laser 2. While measuring the temperature with the infrared detection device (detection element) 1 and obtaining the first surface temperature data D24, the first scan (forward scan F) and the surface 2a of the inspection object 4 with the laser 2 are heated. After the surface temperature of the inspection object 4 is measured by the infrared detection device (detection element) 1 and the second scan (reverse scan B) for obtaining the second surface temperature data D25 is performed, the first surface is obtained. From the first reference value K3 in the temperature data D24 Large data is positive, data smaller than the first reference value K3 is negative, and data larger than a predetermined second reference value K4 in the second surface temperature data D25 is positive, and the second reference value K4 Since the third surface temperature data D26 is obtained by multiplying the first surface temperature data D24 and the second surface temperature data D25 after that, the third surface temperature data D26 is obtained. When 6 (crack) is deep, in the third surface temperature data D26, the defect detection signal KD26 and the noise signal ND26 are divided into positive and negative, and the distinction between the defect detection signal KD26 and the noise signal ND26 becomes clear. When the defect 6 is shallow in the inspection method, the third surface temperature data D16 has a significant difference in the magnitude of the defect detection signal and the noise signal as described above. The distinction between the knowledge signal KD26 and the noise signal ND26 becomes clear, so that the defect detection signals KD16 and KD26 caused by the defect 6 are reliably included in the third surface temperature data D16 and D24 regardless of the depth of the defect 6. It can be determined that it is included, and the defect 6 can be reliably detected.

<Embodiment 3>
FIGS. 5A and 5B are explanatory diagrams of an inspection method according to Embodiment 3 of the present invention. FIG. 5A shows a marker installation state, and FIG. 5B shows a waveform diagram.

  In the third embodiment as well, the configuration of the surface inspection apparatus is the same as that in the first embodiment, so FIG. 1 will be referred to and illustration and detailed description thereof will be omitted here.

  In the third embodiment, first, as shown in FIG. 5A, a plurality (five in the illustrated example) of markers 11 are provided on the surface 4a of the inspection object 4 before scanning. The marker 11 is made of a material having a different emissivity from that of the inspection object 4 (in the illustrated example, a material having a higher emissivity than the inspection object 4). For example, a metal member formed in a rectangular shape is used as the inspection object. 4 can be provided on the surface 4a of the inspection object 4 by sticking it on the surface 4a of the inspection object 4 or drawing it on the surface 4a of the inspection object 4 with ink (magic ink or the like). In addition, the markers 11 are arranged at equal intervals along the scanning direction in a region adjacent to the defect inspection region (defect inspection range) on the surface 4 a of the inspection object 4.

  Next, as shown in FIG. 5B, the forward scanning F that is the first scanning is performed to obtain the first surface temperature data D31 that is the forward scanning data, and then the backward scanning that is the second scanning. Scan B is performed to obtain second surface temperature data D32 which is reverse scan data. That is, in the forward scanning F, while the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a) Radiant heat) is measured by the infrared detection device (detection element) 1 to obtain first surface temperature data D31 (surface temperature distribution data) after heating. Similarly, in reverse scanning B, the surface 4a of the inspection object 4 is heated by the laser 2 (irradiating the surface 4a with the laser beam 2a), and the temperature of the heated surface 4a of the inspection object 4 (from the surface 4a). Radiant heat) is measured by the infrared detection device (detection element) 1 to obtain second surface temperature data D32 (surface temperature distribution data) after heating.

  When there is a defect 6 on the surface 4a of the inspection object 4, the first surface temperature data D31 includes a defect detection signal KD31 caused by the defect 6 and a marker detection signal MD31 caused by the marker 11. Thus, the second surface temperature data D32 also includes the defect detection signal KD32 caused by the defect 6 and the marker detection signal MD32 caused by the marker 11.

  The position of the marker detection signal MD31 included in the first surface temperature data D31 and the marker detection signal included in the second surface temperature data D32 due to factors such as mechanical deviation of the surface inspection apparatus. When a positional deviation ID in the scanning direction position occurs at the position of MD32, the position of the second surface temperature data D32 is corrected based on the positional deviation ID (first surface temperature data by the positional deviation ID). The position of the marker detection signal MD32 is made to coincide with the position of the marker detection signal MD31. Thus, the second surface temperature data D33 after position correction is obtained. In the second surface temperature data D33, the marker detection signal MD33 is a signal obtained by correcting the position of the marker detection signal MD32, and the defect detection signal KD33 is a signal obtained by correcting the position of the defect detection signal KD32. Of course, when the second surface temperature data D32 includes a noise signal due to a noise factor, the position of the noise signal is also corrected in the second surface temperature data D33 after position correction. .

  Note that the position of the first surface temperature data D31 is not limited to the second surface temperature data D32, and the position of the first surface temperature data D31 may be corrected based on the positional deviation ID. Further, depending on the displacement state of the surface inspection apparatus position, the marker detection signals MD31 and 32 are not entirely displaced as in the illustrated example, but only a part of the marker detection signals MD31 and MD32 during the investigation. There may be a positional shift. In this case, if the position of the first surface temperature data 31 or the second surface temperature data D32 is corrected based on the position shift IDs of some of the marker detection signals MD31 and MD32 where the position shift occurs. Good.

  Although detailed description is omitted, after performing such misalignment correction, the multiplication processing of the second embodiment (see FIGS. 3B and 4B), or the conventional method described above. Subtraction processing (see FIGS. 3A and 4A) is performed. Further, the multiplication process of the first embodiment may be performed. In this case, the first scan (forward scan) needs to be performed without heating by the laser 2.

  As described above, according to the inspection method of the third embodiment, the inspection object is scanned by scanning the surface 4 a of the inspection object 4 using the infrared detection device (detection element) 1 and the laser 2. In the inspection method for inspecting the vicinity of the surface 4 (whether or not a defect 6 (crack or the like is generated in the vicinity of the surface 4a)), a marker 11 having a different emissivity from the inspection object 4 on the surface 4a of the inspection object 4 While the surface 4a of the inspection object 4 including the region where the marker 11 is provided by the laser 2 is heated (without heating in the case of the first embodiment), the surface of the inspection object 4 is heated. An inspection object including a first scan (forward scan F) in which the temperature is measured by the infrared detection device (detection element) 1 to obtain the first surface temperature data D31 and the region where the marker 11 is provided by the laser 2 This inspection while heating the surface 4a of 4 The surface temperature of the figurine 4 is measured by the infrared detection device (detection element) 1 to perform the second scan (reverse scan B) to obtain the second surface temperature data D32, and the first surface temperature data If a positional deviation ID has occurred between the position of the marker detection signal MD31 included in D31 and the position of the marker detection signal MD32 included in the second surface temperature data D32, the positional deviation ID is After correcting the position of the first surface temperature data D31 or the second surface temperature data D32 based on the above, the multiplication in the second embodiment or the conventional subtraction or the subtraction in the first embodiment is performed. Therefore, even if a positional deviation ID occurs in the first surface temperature data D31 and the second surface temperature data D32 due to a deviation of the surface inspection device, the positional deviation ID is corrected. It can be carried out reliably the subtraction or the multiplication. Therefore, since the distinction between the defect detection signal and the noise signal in the third surface temperature data can be clarified more reliably, defects (cracks and the like) can be detected more reliably.

  Further, according to the inspection method of the third embodiment, a plurality of the markers 11 are provided at equal intervals along the scanning direction. For example, when a deviation occurs in the surface inspection apparatus during the scanning. In addition, since a positional shift caused by this shift occurs in a part of the marker detection signals MD31 and MD32, the first surface temperature data D31 or the second data is based on the positional shift of the partial marker detection signals MD31 and MD32. The position of the surface temperature data D32 can be corrected.

  In the first to third embodiments, the case has been described in which the forward scanning is performed as the first scanning and then the backward scanning is performed as the second scanning. However, the present invention is not necessarily limited thereto. After performing the forward scan as the first scan, the forward scan may be performed again as the second scan.

  In the first to third embodiments, the laser is used as the heating unit. However, the present invention is not necessarily limited to this, and other heating unit (lamp or the like) may be used.

  The present invention relates to an inspection method for inspecting whether a defect such as a crack has occurred near the surface of an inspection object using an infrared detection means and a heating means, and the soundness of the inspection object such as equipment It is useful when applied to evaluation.

It is a figure which shows the outline | summary of the inspection apparatus for enforcing the inspection method which concerns on Example 1 of Embodiment of this invention. It is explanatory drawing of the said inspection method, (a) is an image figure of the signal processing content, (b) is a wave form diagram which shows the signal processing content. (A) is explanatory drawing in case a defect (crack etc.) is a comparatively shallow inspection method, (b) is an inspection method which concerns on Example 2 of Embodiment of this invention, and a defect (crack etc.) exists. It is explanatory drawing when it is comparatively shallow. (A) is explanatory drawing in case a defect (crack etc.) is a comparatively deep inspection method, (b) is the inspection method which concerns on Example 2 of Embodiment of this invention, and a defect (crack etc.) is It is explanatory drawing in the case of comparatively deep. It is explanatory drawing of the inspection method which concerns on Embodiment 3 of this invention, Comprising: (a) is a figure of the installation state of a marker, (b) is a wave form diagram.

Explanation of symbols

1 Infrared detector (detection element)
2 Laser 2a Laser beam 3 Signal processing device 4 Inspection object 4a Surface 5a, 5b Reflective mirror 6 Defect (crack, etc.)
7,8 Edges of defects (cracks, etc.)

Claims (7)

In the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means,
A first scan that obtains first surface temperature data before heating by measuring the surface temperature of the inspection object with the infrared detection means without heating the surface of the inspection object with the heating means;
While the surface of the inspection object is heated by the heating means, the surface temperature of the inspection object is measured by the infrared detection means, and a second scan is performed to obtain second surface temperature data after heating. ,
3. An inspection method comprising obtaining third surface temperature data by subtracting the first surface temperature data from the second surface temperature data. In the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means,
Without heating the surface of the object to be inspected by the heating means, the surface temperature of the object to be inspected is measured by the infrared detecting means, and a first scan is performed to obtain first surface temperature data before heating. ,
While changing the output of the heating means according to the first surface temperature data, the surface temperature of the inspection object is measured by the infrared detection means while the surface of the inspection object is heated by the heating means. And a second scan for obtaining second surface temperature data after heating. In the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means,
A first scan that obtains first surface temperature data by measuring the surface temperature of the inspection object with the infrared detection means while heating the surface of the inspection object with the heating means;
While heating the surface of the inspection object with the heating means, the surface temperature of the inspection object is measured with the infrared detection means, and a second scan to obtain second surface temperature data is performed,
A third surface temperature data is obtained by multiplying the first surface temperature data and the second surface temperature data. The inspection method according to claim 3,
After performing the first scan and the second scan,
In the first surface temperature data, data larger than the first reference value is positive, data smaller than the first reference value is negative, and in the second surface temperature data, the data is larger than the second reference value. Large data is positive, data smaller than the second reference value is negative,
Thereafter, the third surface temperature data is obtained by performing the multiplication. The inspection method according to claim 1, 3 or 4,
At least one marker having a radiation rate different from that of the inspection object is provided on the surface of the inspection object, and the first scan and the second are performed with respect to the surface of the inspection object including a region where the marker is provided. And scanning
And, when there is a positional deviation between the position of the marker detection signal included in the first surface temperature data and the position of the marker detection signal included in the second surface temperature data, After correcting the position of the first surface temperature data or the second surface temperature data based on this displacement,
3. The inspection method according to claim 1, wherein the third surface temperature data is obtained by performing the subtraction or the multiplication. In the inspection method for inspecting the vicinity of the surface of the inspection object by scanning the surface of the inspection object using the infrared detection means and the heating means,
Providing at least one marker having a different emissivity from the inspection object on the surface of the inspection object;
While heating the surface of the inspection object including the area where the marker is provided by the heating means, the surface temperature of the inspection object is measured by the infrared detection means to obtain first surface temperature data. 1 scan,
While heating the surface of the inspection object including the area where the marker is provided by the heating means, the surface temperature of the inspection object is measured by the infrared detection means to obtain second surface temperature data. 2 scans,
And, when there is a positional deviation between the position of the marker detection signal included in the first surface temperature data and the position of the marker detection signal included in the second surface temperature data, Correcting the position of the first surface temperature data or the second surface temperature data based on this positional deviation,
In the first surface temperature data, data larger than the first reference value is positive, data smaller than the first reference value is negative, and in the second surface temperature data, the data is larger than the second reference value. Large data is positive and data smaller than the second reference value is negative.
3. An inspection method comprising obtaining third surface temperature data by subtracting the first surface temperature data from the second surface temperature data. The inspection method according to claim 5 or 6,
An inspection method, wherein a plurality of the markers are provided along a scanning direction.

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