WO2014199869A1

WO2014199869A1 - Infrared inspection device

Info

Publication number: WO2014199869A1
Application number: PCT/JP2014/064688
Authority: WO
Inventors: 吉武　康裕; 秀明笹澤
Original assignee: 株式会社日立ハイテクノロジーズ
Priority date: 2013-06-12
Filing date: 2014-06-03
Publication date: 2014-12-18
Also published as: JP2014240801A

Abstract

A technology is provided that is capable of enhancing, in measurements and inspections using infrared radiation, the accuracy of temperature-difference measurements near the surface of a structure and the accuracy of inspections of the status of defects, deterioration, and the like. An inspection device (1A) has a pulsed laser (2) for irradiating a pulsed laser onto a subject (5); a scanning mirror (23) for scanning the subject (5); an infrared sensor (3) for detecting infrared radiation originating from the subject (5); a control unit (11A) for controlling the irradiation of the pulsed laser (2), the angle of the scanning mirror (23), and the detection of the infrared sensor (3) so that the temperature variation corresponding to the irradiation and non-irradiation of the laser light is measured multiple times for each measured point; an image generation unit (12A) for generating an image including the temperature difference distribution of the area of the subject (5) on the basis of the measured temperature difference values and the scanning mirror angles; and a defect extraction unit (13A) for identifying and extracting defective or degraded portions using the image.

Description

Infrared inspection device

The present invention relates to a measurement and inspection technique using infrared rays. The present invention also relates to an apparatus for measuring the state of temperature or stress on the surface or inside of an object such as a structure by detecting infrared rays, and inspecting a state such as a defect or deterioration.

There is an inspection technique using an infrared sensor or the like as a technique suitable for inspecting structures of social infrastructure such as buildings, bridges, and tunnels. This technique measures and inspects the temperature difference or stress fluctuation state near the surface of the structure by detecting infrared rays emitted from the surface of the structure. This technique uses a phenomenon in which a change in temperature occurs when there is a change in stress, in other words, a principle that a stress change and a temperature difference are correlated. This phenomenon is generally called a thermoelastic effect and is expressed by the following formula (1). In Expression (1), ΔT is a temperature change, K is a thermoelastic coefficient, T is an absolute temperature, and Δσ is a variation of the main stress sum of the object.

ΔT = −K × T × Δσ Equation (1)

The above principle is applied to a technique of applying a certain stress change to a structure that is an object of measurement and inspection and detecting a point where the stress change is different from the other as a defect. Such defects include peeling, cracks, internal cracks, and the like. As a method for detecting the defect, for example, a part having a large temperature difference or a part having a small temperature difference is determined and extracted as a defect.

In the measurement and inspection by the above-mentioned method, in order to generate a stress change actively, means for causing a temperature change from the outside to the object is taken. Examples of the means include means for illuminating the surface of the object with lamp light and means for irradiating laser light.

As prior art examples related to measurement and inspection using the infrared and thermoelastic effects, there are JP-A-62-98243 (Patent Document 1), Non-Patent Document 1, and Patent No. 3776794 (Patent Document 2). It is done.

Patent Document 1 irradiates an object such as an outer wall with laser light, causes a stress change due to expansion due to heat absorption before and after irradiation, and images a temperature difference distribution generated at this time with an infrared camera, thereby causing peeling and the like. An apparatus for detecting defects is described. Patent Document 1 briefly refers to a method of scanning and irradiating laser light.

Non-Patent Document 1 describes an apparatus for detecting defects such as internal cracks by heating an object periodically with a heating lamp and measuring a temperature change accompanying a stress caused by heat absorption with an infrared camera. Yes.

Patent Document 2 discloses an apparatus for detecting defects inside a tunnel wall surface by irradiating a concrete tunnel wall surface, which is an object, with a lamp mounted on a moving body such as a vehicle and taking an image with an infrared line camera. Are listed.

JP-A-62-98243 Japanese Patent No. 3776794

In the prior art examples related to measurement and inspection using infrared rays and thermoelastic effects, there are problems regarding the accuracy of temperature difference measurement near the surface of the structure and the accuracy of inspection of states such as defects and deterioration.

Since the apparatus according to Patent Document 1 measures an infrared ray once per point to be measured, there is a problem in the accuracy of measurement and inspection due to an error in measurement values. Further, the apparatus according to Patent Document 2 has a problem in the accuracy of measurement and inspection because the measurement is performed once per measurement point by the movement of the vehicle with respect to the object.

In addition, the apparatus according to Non-Patent Document 1 has a non-uniform spatial distribution of the energy of the surface to be measured by heating or illumination as a means for giving temperature change and stress change to the surface to be measured. There are challenges.

An object of the present invention is to improve the accuracy of measurement of temperature difference near the surface of a structure and the inspection of a state such as a defect or deterioration in relation to measurement and inspection using the infrared ray and the thermoelastic effect. It is to provide technology that can.

A typical embodiment of the present invention is an infrared inspection apparatus which is an apparatus for measuring an object and inspecting a state such as a defect using infrared rays, and has the following configuration. .

(1) An infrared inspection apparatus according to an embodiment includes a laser unit that irradiates a measurement point on the surface of an object with at least two states of presence or absence of irradiation with the laser beam, and the object with respect to the irradiation of the laser beam. An optical system including a scanning mirror for scanning at least the surface in the first direction, an infrared sensor for detecting at least one infrared ray generated from a measurement point on the surface of the object by irradiation with the laser beam, Infrared detection of the infrared sensor is performed when the laser light irradiation is in two states, and a temperature difference that is a difference between infrared detection signals in the two states is measured for each measurement point. A control unit that controls the laser beam irradiation of the laser unit, the angle of the scanning mirror, and the infrared detection timing of the infrared sensor, and the temperature difference Value, and based on the angle of the scan mirror, having, an image generator for generating an image including a distribution of the temperature difference of the measurement points of a plurality of each in the region of the surface of the object.

(2) An infrared inspection apparatus according to an embodiment includes a laser unit that irradiates a measurement point on a surface of an object with laser light in at least two states of irradiation and the object with respect to the irradiation of the laser light. An optical system including a scanning mirror for scanning the surface of the object in at least the first direction, and detecting infrared rays generated from a measurement point on the surface of the object by irradiation of the laser beam in a line or surface area An infrared camera that captures an image; and a first infrared ray that is detected by the infrared camera in the non-irradiation state by controlling the laser beam to the non-irradiation state by the laser unit in image units of the infrared camera. An image and a second image in which infrared light is detected by the infrared camera when the laser unit is controlled to be irradiated with the laser beam and the irradiation is performed. A control unit for controlling the presence or absence of laser light irradiation of the laser unit, the angle of the scanning mirror, and the detection timing of infrared rays of the infrared camera so as to capture an image of the state, and the irradiation of the first image Based on the measured value of the temperature difference due to the difference between the measured value by the detection of the infrared when there is no state and the measured value by the detection of the infrared when the state of the second image is with the irradiation An image generation unit that generates an image including a temperature difference distribution of a plurality of measurement points in a line or surface area of the surface of the object.

(3) An infrared inspection apparatus according to an embodiment is an infrared inspection apparatus mounted on a moving body, and includes a sensor unit that detects a moving amount or a position of the moving body, and a surface to be measured on a fixed object. A laser unit that irradiates a point with laser light in at least two states of irradiation, and at least a first for irradiating a plurality of measured points on the surface of the object with respect to the irradiation of the laser light. An optical system including a scanning mirror for scanning in a direction, an infrared sensor that detects at least one infrared ray generated from a measurement point on the surface of the object by irradiation of the laser beam, and whether or not the laser beam is irradiated In the two states, the infrared sensor detects infrared rays in two states, and the angle of the scanning mirror is switched for each of a plurality of measurement points on the surface of the object. Detection of the sensor unit, presence / absence of laser light irradiation of the laser unit, angle of the scanning mirror, and detection of infrared light of the infrared sensor so as to measure a temperature difference, which is a difference between infrared detection signals, a plurality of times A calculation unit for calculating a temperature difference distribution for each of a plurality of measurement points on the surface of the object based on a control unit that controls the timing of the sensor, a detection information of the sensor unit, and a measurement value of the temperature difference And having.

(4) The infrared inspection apparatus according to (1) to (3) further includes a defect extraction unit that determines and extracts a defect or a deteriorated portion using the temperature difference distribution image or the temperature difference distribution. .

According to a typical embodiment of the present invention, with respect to measurement and inspection using infrared rays and thermoelastic effects, etc., accuracy of temperature difference measurement near the surface of the structure, and inspection of states such as defects and deterioration Accuracy can be improved.

It is a figure which shows the structure containing the infrared rays inspection apparatus and target object of Embodiment 1 of this invention. 3 is a timing chart showing control by the infrared inspection apparatus according to Embodiment 1. FIG. FIG. 3 is a diagram schematically showing a surface to be measured and a state of scanning in the first embodiment. (A) shows the example of defect determination based on the temperature difference data in Embodiment 1, (b) is a figure which shows the example of defect determination based on the temperature difference data in Embodiment 3. FIG. (A) shows the example of the temperature difference image in Embodiment 1, (b) is a figure which shows the example of the image of a defect extraction result. It is a figure which shows the structure containing the infrared rays inspection apparatus and target object of Embodiment 2 of this invention. FIG. 10 is a timing diagram illustrating control by the infrared inspection apparatus according to the second embodiment. It is a figure which shows the structure containing the infrared rays inspection apparatus, vehicle, and target object of Embodiment 3 of this invention. FIG. 10 is a diagram illustrating a plurality of measurement points that accompany the traveling of a vehicle in a third embodiment. FIG. 10 is a timing diagram illustrating control by the infrared inspection apparatus according to the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

<Embodiment 1>
The infrared inspection apparatus according to the first embodiment will be described with reference to FIGS. The inspection apparatus 1A, which is the infrared inspection apparatus of the first embodiment shown in FIG. 1, is based on the control of the angle θ of the scanning mirror 23, and the pulsed laser beam from the pulse laser 2 to the surface 5a to be measured of the object 5 Is applied to the surface to be measured 5a to apply thermal stress due to active temperature change. The inspection apparatus 1A detects infrared rays from the measurement point on the measurement target surface 5a by the infrared sensor 3 in synchronization with the presence or absence of laser light irradiation. As a result, the inspection apparatus 1A generates an image of the temperature difference or temperature change distribution of the surface to be measured 5a, and uses the image to determine the temperature difference or stress fluctuation, thereby causing a state such as a defect or deterioration such as peeling or cracking. Is extracted.

The inspection apparatus 1A according to the first embodiment has a configuration suitable for inspecting the vicinity of the surface of a building such as a building, a bridge, and a tunnel as the object 5. The inspection apparatus 1A, as a function, inspects the normal state near the surface of the object 5 and the state of defects, deterioration, etc., extracts a portion determined to have a defect, deterioration, or a sign thereof, and outputs it to the user To do.

[Infrared inspection equipment]
FIG. 1 shows a configuration including an inspection apparatus 1A that is an infrared inspection apparatus according to the first embodiment and an object 5 to be measured and inspected. As directions on explanation, in Drawing 1, X and Y which are directions which constitute a level surface, and Z which is a perpendicular direction are shown. In FIG. 1 and the like, the actual distance, size, and the like are omitted.

The object 5 is a fixed structure to be measured and inspected. For example, the object 5 is a wall surface of a building or the like made of a material such as concrete. The object 5 includes a measured surface 5a and measured

points

5b, 5c, and 5d. The surface to be measured 5a is a surface in the Y and Z directions. The surface of the measurement target surface 5a includes a shape such as unevenness depending on the material and the like. The measurement points 5b, 5c, and 5d are examples of points to be measured on the line in the Y direction of the measurement surface 5a. The surface to be measured 5a becomes a line to be measured when only scanning and measurement in the Y direction are performed.

The inspection device 1 A is arranged at a predetermined position and orientation with respect to the object 5. b 1 indicates the distance between the end of the inspection apparatus 1 A and the measurement target surface 5 a of the object 5. The distance b1 is 50 m, for example. b2 indicates a possible range of scanning by the scanning mirror. Details of the optical system of the inspection apparatus 1A are designed according to the distance b1, the scanning range b2, and the like. Note that the length of the scanning range b2 is sufficiently smaller than the distance b1.

The inspection apparatus 1A includes a pulse laser 2, an infrared sensor 3, a collimating lens 21, a dichroic mirror 22, a scanning mirror 23, an objective lens 24, an imaging lens 25, an oscillator 10, a control unit 11A, an image generation unit 12A, and a defect extraction unit 13A. And an input / output unit 14.

The parts such as the control unit 11A, the image generation unit 12A, the defect extraction unit 13A, and the input / output unit 14 can be configured by, for example, a circuit board including a CPU, a ROM, and a RAM, a PC, and the like, and function by software program processing or the like. realizable.

The oscillator 10 oscillates the reference clock c0. The control unit 11A controls the entire inspection apparatus 1A. The control unit 11A controls each unit such as the scanning mirror 23, the pulse laser 2, and the infrared sensor 3 based on the reference clock c0 from the oscillator 10. The controller 11A controls the state of the scanning or deflection angle θ of the scanning mirror 23 by the angle control signal c1. The control unit 11A controls the presence and absence (ON) and absence (OFF) of oscillation and irradiation of the pulsed laser light from the pulse laser 2 by the control signal c2. The control signal c2 is a signal by ON and OFF pulses, for example. The control unit 11A reads out and acquires the infrared intensity signal c3 detected by the infrared sensor 3.

The image generation unit 12A generates an image of a temperature difference distribution corresponding to the area of the measurement target surface 5a of the object 5 using information including the infrared measurement value obtained by the infrared sensor 3 obtained through the control unit 11A. Process. The image has information such as a temperature difference measurement value and a display gradation value associated therewith for each point to be measured. The image generation unit 12A stores data information including the generated image in a storage device (not shown) in the inspection apparatus 1A.

The defect extraction unit 13A uses the image of the temperature difference distribution generated by the image generation unit 12A to determine the normal state, the defect, the deterioration, and the like in the region of the image, and is determined to be the defect, the deterioration, or the like. To extract the part. Then, the defect extraction unit 13A generates information such as an image including the defect extraction result and stores it in a storage device (not shown) in the inspection apparatus 1A.

The defect extraction unit 13A compares the temperature difference of the measurement point with the threshold value using, for example, threshold information of the allowable range as the defect determination process, and if the temperature difference is within the allowable range based on the threshold value, the determination result is obtained. When it is normal and does not fit, the judgment result is regarded as a defect.

The input / output unit 14 receives an operation for using the function of the inspection apparatus 1A by a user and an operation for setting, and performs processing such as input and output of data information. The input / output unit 14 includes an input button, a display device, and the like. When the input / output unit 14 includes a display, the input / output unit 14 displays an image of a temperature difference distribution, an image of a defect extraction result, and the like on the screen. Thereby, the user can judge and confirm the state of the defective portion, etc. by looking at the image displayed on the screen, and can easily perform the measurement and inspection work.

Further, the input / output unit 14 can set setting information such as threshold information of an allowable range for defect determination by the user. Alternatively, threshold information of an allowable range may be set in advance in the inspection apparatus 1A.

The pulse laser 2 is a laser device that oscillates pulsed laser light in response to a control signal c2 from the control unit 11A. The pulse laser 2 irradiates the measurement target surface 5a of the object 5 with laser light intermittently. Thereby, thermal stress or energy distribution is given to the measurement surface 5a for measurement and inspection of the temperature difference. Control is performed so as to assume the presence (ON) and absence (OFF) of pulsed laser light irradiation for each measurement point on the measurement target surface 5a.

The infrared sensor 3 is a point sensor, and in response to the reading and detection control from the control unit 11A, the infrared light corresponding to the measurement point is incident on the sensor surface and detected, and the infrared signal c3. Is output. Infrared intensity correlates with temperature. The temperature difference (ΔT) correlates with the stress fluctuation (Δσ) as shown by the above-described thermoelastic effect equation (1).

The collimating lens 21 converts incident light into parallel light. The dichroic mirror 22 is a wavelength separation mirror. The dichroic mirror 22 reflects a component in a predetermined wavelength band of incident light and transmits a component in another wavelength band.

The scanning mirror 23 has a mechanism that rotates at an angle θ around a rotation axis extending in the Z direction. The scanning mirror 23 is deflected or rotated by controlling the angle θ for scanning in the Y direction by the angle control signal c1 from the control unit 11A. Thereby, the scanning mirror 23 irradiates the reflected light through the objective lens 24 so as to scan the region of the line in the Y direction on the measurement target surface 5a of the object 5.

The objective lens 24 converts incident light into focused light to a measurement point on the measurement target surface 5a that is a focal point. The imaging lens 25 forms an image of incident light on the sensor surface of the infrared sensor 3 that is a focal point. The inspection apparatus 1A according to the first embodiment has an optical system configuration in which a measurement point on the measurement target surface 5a of the object 5 and a sensor surface of the infrared sensor 3 are combined with the imaging lens 25 and the objective lens 24. It is placed in the relationship of imaging by conjugation.

[Optical system]
The flow of light in the optical system of the inspection apparatus 1A is as follows. Light a0, which is pulsed laser light emitted from the pulse laser 2 in the X direction, becomes parallel light a1 by the collimator lens 21. The parallel light a1 is reflected by the dichroic mirror 22 in the Y direction. The reflected light a2 is reflected in the X direction by the scanning mirror 23 according to the control state of the angle θ. The light a3 that has passed through the scanning mirror 23 is emitted from the end of the inspection apparatus 1A to the outside as focused light a4 by the objective lens 24.

The focused light a4 is condensed and irradiated on the measurement point on the measurement surface 5a of the object 5. For example, as a control state of the angle θ of the scanning mirror 23, the state shown in FIG. 1 is set to a state where the reference angle θ0 = 0 degrees. In the case of this reference state, the focused light a4 is condensed on the measurement point 5b on the measurement surface 5a. The measurement point 5 b indicates a reference point that is located in front of the center of the scanning mirror 23 and the principal point of the objective lens 24 in the X direction.

In the vicinity of the measurement point 5b of the measurement surface 5a of the object 5, the temperature rises because it is heated by the irradiated focused light a4, and infrared light having an intensity corresponding to the temperature, particularly far infrared light is generated. To do. Light a5 that is infrared light generated on the measurement target surface 5a of the object 5 travels in the same optical path as the focused light a4 in the opposite direction in the X direction, and enters the objective lens 24 from the end of the inspection apparatus 1A. The light incident on the objective lens 24 is reflected in the Y direction by the scanning mirror 23, and far-infrared light that is light in a predetermined wavelength band passes through the dichroic mirror 22. The light a8 that has passed through the dichroic mirror 22 in the Y direction is incident on the sensor surface of the infrared sensor 3 as the focused light a9 by the imaging lens 25.

As the above-described scanning control, by increasing or decreasing the angle θ of the scanning mirror 23 with respect to the reference angle θ0, the position where the focused light a4 is irradiated on the measurement target surface 5a is measured in the Y direction from the reference measurement point 5b. It moves to the point 5c and the measurement point 5d. The scanning range b2 corresponds to the length between the measured point 5c and the measured point 5d. The point to be measured 5c is a limit point of scanning in the positive direction in the Y direction corresponding to a state in which the angle θ is increased to the maximum angle (set to θ1) in the positive direction. The measurement point 5d is a limit point of scanning in the Y direction negative direction corresponding to a state where the angle θ is increased to the maximum angle (θ2) in the negative direction. In addition, according to control of angle (theta), several to-be-measured points can be taken between to-be-measured point 5c and to-be-measured point 5d.

When performing scanning in the Y direction by irradiation of the focused light a4 based on the laser light on the surface to be measured 5a, the position of the measurement point to be scanned and irradiated moves in the Y direction. At the same time, the light a5, which is infrared light generated from the measurement target surface 5a, similarly moves in the Y direction. For this reason, the above-described scanning forms a distribution of infrared light on the line in the Y direction of the measurement target surface 5a, that is, a spatial temperature distribution and a temperature difference distribution. Since the infrared sensor 3 is a point sensor that detects at one point, the distribution is detected as an infrared intensity signal c3 in time series. The control unit 11A and the image generation unit 12A use the infrared intensity signal c3 read from the infrared sensor 3 and the information on the angle θ at the time of scanning, and the temperature difference in the region of the line in the Y direction of the measurement surface 5a. To understand the distribution of The angle θ and the position of the measurement point have a correspondence relationship.

[Design example]
A design example of the optical system and the like of the inspection apparatus 1A is as follows. In the pulse laser 2, the wavelength of the laser beam is designed according to the characteristics of the object 5 and the surrounding environment. In this example, the material of the object 5 is concrete. In the case of concrete, there are a 1 μm band, a wavelength of 1.5 μm band, a wavelength of 2 μm band, and the like as wavelengths with relatively large absorption of laser light. Correspondingly, as the pulse laser 2, a YAG solid-state laser (YAG: yttrium, aluminum, garnet) with a wavelength of 1 μm, a Yb fiber laser (Yb: ytterbium), an Er fiber laser (Er: Erbium), Tm fiber laser with a wavelength of 2 μm band (Tm: thulium), etc. are candidates. In the first embodiment, a YAG solid-state laser is used as the pulse laser 2. A YAG solid-state laser can oscillate by an external input pulse.

In this example, the dichroic mirror 22 has a function of reflecting a wavelength of 8 μm or less and transmitting a wavelength of 8 μm or more. The wavelength 8 μm at the boundary between reflection and transmission is designed according to the characteristics of the pulse laser 2, the infrared sensor 3, the object 5, and the like.

Infrared light generated from the surface of the object 5 has various wavelengths, but far-infrared light having a wavelength of 8 μm or more is suitable for detection because it is less absorbed by the atmosphere. In the first embodiment, a wavelength of 8 μm is selected as a boundary between transmission and reflection of the dichroic mirror 22 in order to efficiently detect far infrared rays or long wavelength infrared rays, which are infrared rays having a wavelength of 8 μm or more, with the infrared sensor 3.

Depending on the design of the distance b1 and the scanning range b2, the size of the sensor surface of the infrared sensor 3 is about 1 mm.

[Scanning and Modification]
In the configuration of the inspection apparatus 1A according to the first embodiment shown in FIG. 1, the laser beam irradiation and scanning control of the surface to be measured 5a is controlled only in the Y direction by the angle θ of the scanning mirror 23. Accordingly, it is possible to measure and inspect the temperature difference distribution in the one-dimensional line region in the Y direction of the measurement target surface 5a in one scan. Further, the inspection apparatus 1A may have a mechanism for translating the optical system in the Z direction so that the irradiation position can be translated in the Z direction. Thus, by controlling the repetition of scanning in the Y direction a plurality of times, it is possible to measure and inspect the temperature difference distribution in the two-dimensional surface region.

As a modification of the first embodiment, the scanning mirror 23 and the control unit 11A in FIG. 1 are not limited to scanning in the Y direction, and may be configured to be able to scan in other directions as follows. As a first modification of the first embodiment, the inspection apparatus 1A may be configured such that the scanning mirror 23 controls the angle φ for scanning in the Z direction with the rotation axis as the Y direction.

As a second modification, the inspection apparatus 1A includes a first scanning mirror 23 that can control the scanning angle θ in the Y direction and a second scanning mirror 23 that can control the scanning angle φ in the Z direction. It is good also as a structure provided with both. The controller 11A individually controls the two scanning mirrors 23. Thereby, measurement and inspection by scanning in both the Y direction and the Z direction can be performed on the measurement target surface 5a.

As a third modification, the inspection apparatus 1A may have a configuration in which both the scanning angle θ in the Y direction and the scanning angle φ in the Z direction can be simultaneously controlled as one scanning mirror 23. As a result, it is possible to measure and inspect the temperature difference distribution by freely scanning in the Y direction and the Z direction in the two-dimensional surface area of the measurement target surface 5a.

[Scanning and measurement surface]
As a supplement, FIG. 3 simply shows a state of scanning on the measurement target surface 5a by controlling the angle θ of the scanning mirror 23 in a plane in the Y and Z directions. In the measurement target surface 5a, a circle 300 indicates a plurality of measurement points or candidate points. Reference numeral 301 denotes scanning in the Y direction by controlling the angle θ of the scanning mirror 23. Reference numeral 302 denotes scanning in the Z direction by controlling the angle φ of the scanning mirror 23. The measurement point 5b indicates a reference point corresponding to a state where the reference angle θ0 = 0 degrees. The left direction in the figure is the Y direction positive direction and the angle θ positive direction, and the right direction in the figure is the Y direction negative direction and the angle θ negative direction. In addition, how to take angle (theta) etc. is an example, and is not limited. For example, the angle θ may be controlled to be deflected from the reference angle θ0 only in one of the positive direction and the negative direction.

By controlling the angle θ of the scanning mirror 23, a line area in the Y direction can be scanned as indicated by 301, and a plurality of measurement points 300 on the line can be measured. Similarly, by controlling the angle φ of the scanning mirror 23, a region of a line in the Z direction as in 302 can be scanned, and a plurality of measurement points 300 on the line can be measured.

[control method]
FIG. 2 shows a timing chart of each signal of control as a control method by the inspection apparatus 1A of the first embodiment.

(A) shows a reference clock c0 given from the oscillator 10 to the control unit 11A. 201 indicates one clock pulse in the reference clock c0. Based on the reference clock c0 in (a), the control unit 11A oscillates and irradiates the pulse laser 2 in (b), detects and reads out the infrared sensor 3 in (c), and angle θ of the scanning mirror 23 in (d). Control the timing of switching.

(B) shows the control of oscillation (irradiation) and irradiation (OFF) of pulsed laser light of the pulse laser 2 and irradiation corresponding to the control signal c2. Reference numeral 202 denotes one pulse in the ON state. The OFF state is shown during the ON state pulse 202. When the control signal c 2 is turned ON, laser light with a pulse 202 having a short width is emitted by thermal excitation of the pulse laser 2. The ON pulse 202 in (b) is emitted synchronously with the ratio of one pulse 202 to the four clock pulses 201 of the reference clock c0 in (a).

(C) shows detection and readout control of the infrared sensor 3.

Reference numerals

203 and 204 denote one measurement value detection and readout pulse, respectively. The detection or measurement of infrared rays by the infrared sensor 3 in (c) is controlled so as to be performed at a timing synchronized with the non-irradiation (OFF) and presence (ON) states of the pulse laser 2 in (b). The controller 11A controls the synchronization by each signal based on the reference clock c0.

Reference numeral 203 denotes a detection and readout pulse when the laser beam pulse 202 is not irradiated (OFF) in (b), and reference numeral 204 denotes a laser beam pulse irradiation (ON) when (b) is performed (ON). Detection and readout pulses. The

pulses

203 and 204 in (c) are detected and read out at a rate of once with respect to the two clock pulses 201 of the reference clock c0 in (a). 11 A of control parts read the signal c3 of the measured value of an infrared intensity from the infrared sensor 3 according to the said

pulses

203 and 204. FIG.

S (s1 to s8, etc.) indicates the measurement value of the infrared sensor 3 corresponding to the timing of the

pulses

203 and 204 before and after the laser light irradiation. d (d1 to d4, etc.) indicates a temperature difference (ΔT) due to the difference of the measurement value s of the infrared sensor 3. The temperature difference d is a difference value between the measured value s when there is no irradiation (OFF) and the measured value s when there is irradiation (ON). For example, the difference between the measured value s1 at the time of the pulse 203 and the measured value s2 at the time of the next pulse 204 is obtained as the temperature difference d1. v (v1 to v3, etc.) represents a temperature difference based on an average value of a plurality of temperature differences d (d1 to d4, etc.). For example, the average value of the four temperature differences d1 to d4 is the temperature difference v2.

(D) shows the deflection control of the angle θ of the scanning mirror 23 corresponding to the angle control signal c1. The vertical axis is the angle θ. Reference numeral 206 denotes a signal and a state in which the angle θ is set to 0 degrees, which is the reference angle θ0, corresponding to the position of the reference measurement point 5b at time 212 from time t2 to t3. In the state and time of one angle θ, four temperature differences d are measured for one measurement point 5b by the measurement values s of four pulses 202 in (b) and eight pulses in (c). Measurement is performed. Then, a temperature difference v2 by an average value of the four temperature differences d (d1 to d4) is obtained.

The controller 11A controls the angle θ of the scanning mirror 23 in (d) at a timing synchronized with the clock pulse 201 of the reference clock c0 at a rate of once for the four pulses 202 in (b). The unit amount (θu) is switched to increase or decrease. The switching of the angle θ is performed at the timing of one clock pulse 201 in (a) as indicated by t1, t2, and t3. The timing of the clock pulse 201 is an intermediate timing between the pulse 204 of (c) corresponding to the ON pulse 202 of (b) and the pulse 203 of (c) corresponding to the OFF state of (b).

Θu indicates the unit amount of increase / decrease of the angle θ. Reference numeral 205 denotes a state in which the angle θ is controlled by an angle (−θu) smaller by one unit amount in the negative direction with respect to the reference angle θ0 at a time 211 from time t1 to time t2. In this state, a temperature difference v1 is obtained. Reference numeral 207 denotes a state in which the angle θ is controlled by an angle (+ θu) larger by one unit amount in the positive direction with respect to the reference angle θ0 at time 213 from time t3 to t4. In this state, a temperature difference v3 is obtained. The same applies to angle states other than those shown in the figure.

By controlling the pulse laser 2 in (b) and the infrared sensor 3 in (c) by the control unit 11A, the

pulses

203 and 204 in (c) corresponding to two states of ON and OFF of the pulse 202 in (b) are controlled. An infrared measurement value s is obtained at the timing. 11 A of control parts read the infrared intensity signal c3 corresponding to the measured value s from the infrared sensor 3, and acquire it.

The image generation unit 12A calculates the temperature difference d from the difference between the measurement values s corresponding to the presence or absence of laser light irradiation. The image generation unit 12A calculates a temperature difference v obtained by averaging a plurality of temperature differences d per measurement point corresponding to the state of one angle θ. The image generation unit 12A similarly obtains the temperature difference v for each measurement point in the region of the line on the measurement surface 5a. Thereby, the image generation unit 12A generates an image of a temperature difference distribution corresponding to the region of the measurement target surface 5a. The image generation unit 12A combines the information of the measurement value s and the temperature difference d and the information of the angle θ of the scanning mirror 23, and grasps the position of the scanning and measurement point on the measurement surface 5a from the angle θ. Generate an image of the temperature difference distribution.

[Temperature difference image and defect determination]
FIG. 4A shows an example of part of the data of the temperature difference distribution image by the image generation unit 12A and the defect determination processing by the defect extraction unit 13A in the first embodiment. In the temperature difference data, the horizontal axis indicates points A to I, which are a plurality of measurement points at positions in the Y direction of the measurement surface 5a. The vertical axis indicates the measured value of the temperature difference (ΔT) at the measurement point, in particular, the temperature difference v based on the average value described above.

401 indicates an allowable range as setting information for defect determination, h1 indicates a lower limit threshold value, and h2 indicates an upper limit threshold value. For example, points A to D indicated by 402 are within the allowable range 401, and points E to I indicated by 403 are smaller than the threshold value h1 and outside the allowable range 401. The defect extraction unit 13A compares the temperature difference value with a threshold value, and determines that the defect is normal if it is within the allowable range 401, and is defective or deteriorated if it is outside the allowable range 401.

The region 403 including the points E to I determined to be defective, deteriorated, etc. has a small temperature difference and stress fluctuation, so that the state where peeling or the like is occurring in the vicinity of the region is highly likely to occur. Represents. Conversely, when the temperature difference exceeds the threshold value h2, the temperature difference and stress fluctuation are large, indicating that stress concentration is occurring near the area due to cracks or the like, or the possibility of occurrence is high. ing.

FIG. 5A simply shows an example of the temperature difference distribution image 501 generated by the image generation unit 12A. An image 501 shows an image of a temperature difference distribution corresponding to a case where the measured surface 5a of the object 5 is made of concrete tiles or the like. For example, by repeating the above-described Y-direction scanning a plurality of times in the same manner while changing the position in the Z-direction depending on the position of the inspection apparatus 1A on the surface to be measured 5a in the Y- and Z-directions, In this example, an image 501 is generated. Note that the actual image has a value of the temperature difference d or a gradation value associated therewith for each pixel corresponding to the measurement point. The image generation unit 12A may generate a display image that is easy for the user to visually check by performing display image processing on the measurement value.

The partial area 503 in the image 501 corresponds to a partial tile, but the temperature difference is smaller than the area around the area 503. As a result, as in the example of FIG. 4A, the region 503 is extracted as a defect when the temperature difference is outside the allowable range 401. The defect extraction unit 13A determines and extracts the defect portion by processing such as threshold comparison as shown in FIG. 4A or relative comparison of values in the image.

5B shows an image 502 including a defect portion region 504 determined and extracted by the defect extraction unit 13A based on the image 501 in FIG. 5A. The defective portion region 504 corresponds to the region 503. In this case, from the relationship between the temperature difference (ΔT) and the stress (Δσ), the region 504 indicates that stress or stress fluctuation is small. That is, the region 504 indicates that peeling or the like is likely to occur. On the other hand, in the case of a crack or the like, stress concentration occurs, so that the temperature difference becomes larger than the surroundings. In this case, extraction can be performed in the same manner as described above.

[Effects]
As described above, the inspection apparatus 1A according to the first embodiment has the spatial and temporal uniformity related to heating for measurement and inspection, the measurement of infrared rays and temperature differences a plurality of times per point to be measured, and the pulse laser 2 And measuring the temperature difference before and after the irradiation of the pulsed laser beam by the synchronous control of the infrared sensor 3. Thus, the first embodiment relates to the measurement and inspection using infrared rays and the thermoelastic effect, etc., and the accuracy of measurement of the temperature difference near the surface of the structure that is the object 5 and the inspection of the state such as defects and deterioration. Accuracy can be improved. As a result, defects such as defects and deterioration near the surface of the object 5 and signs thereof can be detected at an early stage. For example, measures for maintaining the safety of structures such as buildings, bridges and tunnels can be realized quickly and reliably.

The inspection apparatus 1A according to the first embodiment has a plurality of points per measurement point by the infrared sensor 3 while scanning the area of the measurement surface 5a of the object 5 with the focused light a4 of the laser beam by the pulse laser 2 and the scanning mirror 23. Measure the infrared and temperature difference of the times. Then, the inspection apparatus 1A obtains an image of the distribution of the temperature differences v by averaging the measured values of the plurality of temperature differences d. This reduces measurement errors. For example, the measurement error can be reduced to ½ by using an average value of four temperature differences d for each point. Thereby, 1 A of inspection apparatuses can measure an infrared rays and a temperature difference with high precision with respect to the prior art example which measures once per point.

Further, in the inspection apparatus 1A of the first embodiment, the region of the measurement target surface 5a of the object 5 is scanned spatially and temporally uniformly by the focused light a4 by the irradiation of the pulsed laser beam. Accordingly, the inspection apparatus 1A has higher uniformity in the state of spatial distribution of thermal stress or energy in the area of the surface to be measured 5a than the configuration of the lamp batch irradiation or the like of the prior art example. As a result, the inspection apparatus 1A is more accurate in measuring the temperature difference distribution by the infrared sensor 3 than in the prior art. As a result, the accuracy of extracting defects such as peeling and cracks from the image of the temperature difference distribution on the surface to be measured 5a increases.

The following is a comparison of the first embodiment with the configuration according to the prior art example described above. In the apparatus according to Patent Document 1, an error occurs in the measurement of the temperature difference before and after one laser irradiation per point. Further, when considering the temperature measurement before and after scanning the surface to be measured by the laser, there is a time difference between the start point and the end point of the scan. For this reason, the amount of change in stress differs between the start point and end point of scanning due to thermal diffusion during scanning. As a result, when infrared rays are detected, a temperature gradient occurs as an error between the start point and the end point of scanning. Thereby, the precision at the time of detecting a defect based on a temperature difference falls.

Further, in the apparatus according to Patent Document 2, since the lamp irradiation is performed only once on the measurement target point of the object when the vehicle is traveling, the measurement is performed once per point. As a result, an error occurs in the measurement of the temperature difference in the same manner as described above, and the accuracy decreases.

In the apparatus according to Non-Patent Document 1, measurement is performed with an infrared camera in conjunction with periodic heating by a heating lamp. Therefore, the accuracy of temperature difference measurement is improved as compared with the apparatus according to Patent Document 1, but due to the non-uniformity of the illuminance distribution when the entire surface of the object is illuminated with a heating lamp, uniform stress changes on the surface of the object Can not give. As a result, the accuracy of measurement and defect detection decreases.

<Embodiment 2>
Next, an infrared inspection apparatus according to the second embodiment will be described with reference to FIGS. The inspection apparatus 1B, which is the infrared inspection apparatus of the second embodiment shown in FIG. 6, is capable of imaging that detects infrared rays in a two-dimensional surface area as a different element from the inspection apparatus 1A of the first embodiment. Infrared camera 4 was introduced. The inspection apparatus 1B of the second embodiment eliminates the dichroic mirror 22 of FIG. 1 and the imaging lens 25 and the infrared sensor 3 installed in the Y direction, and instead, between the objective lens 24 and the object 5. The dichroic mirror 27 was installed in The infrared camera 4 was installed in the Y direction, which is the reflection direction of the dichroic mirror 27, via the telephoto lens 28.

[Infrared inspection equipment]
FIG. 6 shows a configuration including the inspection apparatus 1B and the object 5 according to the second embodiment. The inspection apparatus 1B according to the second embodiment includes a pulse laser 2, an infrared camera 4, a collimator lens 21, a reflection mirror 29, a scanning mirror 23B, an objective lens 24, a dichroic mirror 27, a telephoto lens 28, a control unit 11B, and an image generation unit 12B. A defect extraction unit 13B and an input / output unit 14.

The measured surface 5a of the object 5 includes a surface area in the Y and Z directions. R represents an imaging range for a half angle corresponding to the length of the measured point 5b and the measured point 5c. The scanning range b2 is 2 × R. L indicates the distance between the center or rotation axis of the scanning mirror 23B and the reference measurement point 5b of the measurement target surface 5a of the object 5.

The infrared camera 4 enters infrared rays into an imaging lens or a sensor surface and takes an infrared intensity distribution as an image. The sensor surface of the infrared camera 4 is a two-dimensional surface in the X and Z directions, and includes an array of a plurality of pixels. The pixel size corresponding to the measurement of one point on the sensor surface of the infrared camera 4 is about 10 μm. A read output signal c4 from the infrared camera 4 is a signal of a two-dimensional captured image including an infrared intensity distribution.

The infrared camera 4 has a configuration capable of controlling imaging and reading in units of images. Therefore, in the second embodiment, the control unit 11B controls the measurement of the temperature difference by infrared rays in correspondence with the reading of the image unit of the infrared camera 4. The control unit 11B reads out and controls the signal c4 for each image from the infrared camera 4.

The control unit 11B controls the scanning mirror 23B, the pulse laser 2 and the like using the signal c4 read from the infrared camera 4 as a reference clock. The controller 11B controls both the angle θ for scanning in the Y direction of the scanning mirror 23B and the angle φ for scanning in the Z direction by the angle control signal c1. The control unit 11B controls the pulse laser 2 by the control signal c2 as in the first embodiment. By controlling the scanning mirror 23B and the pulse laser 2 from the control unit 11B, a two-dimensional surface area of the measurement target surface 5a is scanned, and thermal stress is applied. Based on the control of the control unit 11B, the inspection apparatus 1B captures an image when the laser beam from the pulse laser 2 is irradiated (ON) and an image when the laser beam is not irradiated (OFF).

The image generation unit 12B obtains an infrared intensity signal c4 from the infrared camera 4 from the control unit 11B, and performs processing for generating an image of a temperature difference distribution in the surface area of the measurement target surface 5a. The image generation unit 12B generates an image of a temperature difference distribution based on a difference between an image with laser light irradiation (ON) and an image with no laser light irradiation (OFF).

As in the first embodiment, the defect extraction unit 13B uses the image of the temperature difference distribution to perform processing for determining and extracting a normal state and a state such as a defect and deterioration, and uses the result through the input / output unit 14 Output to the user.

The reflection mirror 29 is disposed at the position of the dichroic mirror 22 in FIG. 1, and reflects the light a1 from the X direction in the Y direction. Note that the reflection mirror 29 can be omitted when the pulse laser 2 emits light in the Y direction.

The scanning mirror 23B has a configuration capable of simultaneously controlling both the angle θ for scanning in the Y direction and the angle φ for scanning in the Z direction in accordance with the angle control signal c1 from the control unit 11B. The state of scanning of the area of the two-dimensional surface on the measurement target surface 5a is the same as that in FIG. In the second embodiment, the infrared intensity distribution is imaged on the two-dimensional sensor surface of the infrared camera 4 in correspondence with the scanning of the two-dimensional surface on the measurement target surface 5a.

The dichroic mirror 27 is a wavelength separation mirror having a function of transmitting light having a wavelength of 8 μm or less and reflecting light having a wavelength of 8 μm or more, contrary to the dichroic mirror 22 of the first embodiment. The dichroic mirror 27 transmits the laser light from the pulse laser 2 and reflects the infrared light from the object 5.

The telephoto lens 28 is an imaging lens installed together with the infrared camera 4. In the configuration of the optical system according to Embodiment 2, the telephoto lens 28, which is one imaging lens, places the measurement point of the object 5 and the imaging lens or sensor surface of the infrared camera 4 in an imaging relationship by conjugation. It is burned.

The light flow in the optical system of the inspection apparatus 1B of the second embodiment is as follows. The light a0 that is pulsed laser light emitted from the pulse laser 2 becomes parallel light a1 through the collimator lens 21, and is reflected by the reflection mirror 29 in the Y direction. The reflected light a2 is reflected in the X direction by the scanning mirror 23B according to the control state of the angle θ and the angle φ. The light a 3 reflected by the scanning mirror 23 B becomes focused light a 11 through the objective lens 24 and is incident on the dichroic mirror 27.

The dichroic mirror 27 transmits light having a wavelength of 8 μm or less in the focused light a11. The focused light a 12 that has passed through the dichroic mirror 27 is emitted from the end of the inspection apparatus 1 B to the outside, and is irradiated on the measurement point on the measurement surface 5 a of the object 5. The infrared light a13 generated from the measurement point on the measurement target surface 5a returns along the optical path in the X direction, is incident from the end of the inspection apparatus 1B, and far-infrared light having a wavelength of 8 μm or more is emitted from the dichroic mirror 27. Reflected in the Y direction.

The light a14 reflected by the dichroic mirror 27 enters the telephoto lens 28, and the light a15 via the telephoto lens 28 forms an image on the imaging lens or sensor surface of the infrared camera 4. The infrared camera 4 picks up the infrared intensity of the area of the surface to be measured 5a.

The scanning range b2 of the measurement surface 5a of the object 5 is determined by the size of the sensor surface of the infrared camera 4 and the magnification of the telephoto lens 28. The maximum deflection angle (referred to as θmax) of the angle θ of the scanning mirror 23B is determined by the following formula (2) so as to match the imaging range R for a half angle. Since R / L is sufficiently small, the angle θmax can be obtained by R / 2L.

Θmax = (1/2) × arctan (R / L) ≈R / 2L (2)

The pixel size of the sensor surface of the infrared camera 4 in the second embodiment is about 10 μm, and the sensor surface size of the infrared sensor 3 in the first embodiment is about 1 mm. The pixel size of the second embodiment is about 1/100 of the size of the sensor surface of the first embodiment. Therefore, when the scanning range b2 is constant, the use of the infrared camera 4 can provide a spatial resolution that is 100 times as fine as that of the first embodiment. That is, according to the second embodiment, it is possible to extract a smaller defect.

[control method]
FIG. 7 shows a timing chart of control in the inspection apparatus 1B of the second embodiment. F 1 and F 2 indicate times corresponding to capturing one image by the infrared camera 4. In FIG. 7, for simplification of description, regarding the scanning and imaging of one image on the measurement target surface 5a, measurement of six pixels corresponding to six measurement points by scanning one line in the Y direction is performed. Only the part is shown. A plurality of other lines in the Y direction and the Z direction in the surface area are similarly subjected to scanning and imaging control, whereby a captured image of the two-dimensional surface area is obtained.

(A) shows a pixel detection and readout clock corresponding to the detection and readout signal c4 of the infrared camera 4, which is a reference for control. Reference numeral 701 denotes one clock pulse corresponding to detection and readout of one pixel. In the second embodiment, since it is necessary to make the sensitivity of each pixel of the image captured by the infrared camera 4 constant, the readout clock 701 that is the pixel accumulation time of the infrared camera 4 is always kept constant. Thereby, the spatial uniformity of the scanning and irradiation of the laser beam on the measurement target surface 5a is ensured. In response to this, the inspection apparatus 1B uses the clock of the infrared camera 4 of (a) as a reference clock for overall control.

(B) shows a double wave clock which is a clock obtained by doubling the frequency of the clock of the infrared camera 4 of (a). The control unit 11B internally generates a clock pulse 702 of (b) as a harmonic wave of the clock pulse 701 of (a). The double-wave clock pulse 702 in (b) gives the switching timing of the irradiation control signal 703 in (c) and the control signal 705 for controlling the angle θ of the scanning mirror 23B in (e).

(C) is an irradiation control signal 703 for controlling the ON and OFF states of irradiation of the pulse laser 2 of (d) in units of images. Based on the signals (a) and (b), the controller 11B internally generates an irradiation control signal 703 (c). The signal 703 is included in the control signal c2. The signal 703 is turned off at the time corresponding to the first image capturing indicated by F1 and time t1 to t2, and is turned on at the time corresponding to the second image capturing indicated by F2 and time t2 to t3. Put into a state. In the off state of F1, during the detection and readout of all pixels of the image picked up by the infrared camera 4, the laser light irradiation of (d) is not turned on and off. In the next ON state of F2, during the detection and readout of all pixels of the image picked up by the infrared camera 4, repetition (ON) and non-OFF (OFF) of laser light irradiation of (d) is performed.

(D) shows control signals for turning on and off the irradiation of the pulse laser 2. Reference numeral 704 denotes a pulse with irradiation (ON). The pulse 704 in (d) is emitted in synchronization with the clock pulse 701 in (a) only when the irradiation control signal 703 in (c) is on. The example of (d) shows the case of only six pulses 704 corresponding to the measurement of six measurement points by scanning one line in the Y direction.

(E) shows a signal 705 for controlling the angle θ of the scanning mirror 23B. The signal 705 in (e) is controlled in synchronism so that the angle is switched at a timing shifted by a half cycle with respect to the readout clock 701 in (a) and at the timing of the double-frequency clock pulse 702 in (b). The In the example of (e), switching of six angle states is shown corresponding to six measurement points of one line in the Y direction.

In the inspection apparatus 1B according to the second embodiment, the temperature difference is measured using temporally separated measurement points between the preceding and succeeding images, such as F1 and F2, corresponding to the on / off states of laser light irradiation. . S1 etc. in (a) show the measured value of the pixel corresponding to the measurement point by the detection at the timing of the clock pulse 701 of the infrared camera 4. For example, the measurement value s1 in the F1 image and the measurement value s1 in the F2 image correspond to the position in the captured image and the position of the measurement point in the measurement target surface 5a. Using the measurement value at each clock pulse 701 in (a), for example, the pixel measurement value s1 at the time of the first clock pulse 701 of F1 in the off state and the corresponding first value of F2 in the on state The difference from the measured value s1 of the pixel at the time of the clock pulse 701 is the temperature difference d1 (ΔT) at the measurement point of the pixel. Similarly, a temperature difference is obtained for each pixel at the measurement point according to the angular state of (e).

The scanning and measurement of the two-dimensional surface area by controlling the angle θ and the angle φ are as follows, for example. First, a scan including, for example, six measurement points on one line in the first Y direction in the surface area of the scan range b2 is performed in the same manner as in FIG. Subsequently, the angle φ in the Z direction is increased or decreased by a predetermined unit amount, and scanning of one line in the next Y direction is similarly performed. Similarly, all the lines in the Y direction of the scanning range b2 are scanned while shifting the angle φ in the Z direction. Thus, all the measurement points and pixels in the two-dimensional surface area are measured within the time corresponding to one image. The measurement in units of images is performed according to the irradiation OFF and ON control in (c) as shown in F1 and F2 in FIG.

7 A pair of images corresponding to the presence / absence of laser light irradiation are captured in front and back in time by control like F1 and F2 in FIG. The image generation unit 12B generates an image of the distribution of the temperature difference d (ΔT) based on the difference between these two sets of images and the difference between the measured values between the pixels. Then, the defect extraction unit 13B performs defect determination processing from the image of the temperature difference distribution, extracts the defect portion, and outputs an image including the result, as in the first embodiment.

Further, in the second embodiment, the image unit control such as F1 and F2 in FIG. 7 is repeated a plurality of times in the same manner, so that a plurality of measurement values are obtained for each point to be measured, and the average value thereof is obtained. A temperature difference v may be obtained.

[Effects]
As described above, according to the inspection apparatus 1B of the second embodiment, spatial and temporal uniformity related to heating for measurement and inspection, measurement of infrared rays and temperature differences multiple times per point to be measured, pulse It has a configuration such as measurement of a temperature difference before and after irradiation of pulsed laser light by synchronous control of the laser 2 and the infrared camera 4. As a result, the second embodiment is similar to the first embodiment in terms of the measurement accuracy and the defect of the temperature difference in the vicinity of the surface of the structure that is the object 5 with respect to measurement and inspection using infrared rays and thermoelastic effects. It is possible to improve the accuracy of inspection of conditions such as deterioration and deterioration.

In the second embodiment, the configuration including the scanning mirror 23B performs scanning by irradiating a uniform laser beam in a two-dimensional surface area of the surface to be measured 5a, and the thermal stress or energy spatially on the surface to be measured 5a. High uniformity of distribution. Therefore, the temperature difference can be measured with high accuracy. Further, in the second embodiment, the spatial resolution can be increased 100 times as compared with the first embodiment by the configuration including the infrared camera 4 as described above. Thereby, defect extraction can be performed with high accuracy and a state such as a fine crack can be easily detected.

As a modification of the second embodiment, the scanning range by the laser light may be a one-dimensional line region such as the Y direction or the Z direction, and the imaging range by the infrared camera 4 may be a one-dimensional line region.

<Embodiment 3>
Next, an infrared inspection apparatus according to the third embodiment will be described with reference to FIGS. An inspection apparatus 1C, which is an infrared inspection apparatus of the third embodiment shown in FIG. 8, is the same as that of the first embodiment in terms of elements such as an optical system, but is an in-vehicle inspection apparatus as a different configuration. The inspection apparatus 1 C measures and inspects a plurality of measurement points on the measurement target surface 5 a of the target object 5 while moving as the vehicle 6 travels. During the movement, the inspection apparatus 1C rotates or deflects the scanning mirror 23C so that measurement is performed a plurality of times per point with respect to the measurement point at a fixed position without moving the laser irradiation point. Is controlled.

[Infrared inspection equipment]
FIG. 8 shows a configuration including the inspection device 1 C according to the third embodiment, the vehicle 6 on which the inspection device 1 C is mounted, and the object 5. The inspection device 1 C is mounted on the vehicle body of the vehicle 6. In the vehicle 6, at least one movement amount sensor 31 is attached to the wheel 6a. The vehicle 6 may be another moving body. The inspection apparatus 1C according to Embodiment 3 may be viewed as an inspection apparatus or an inspection system as a whole including the vehicle 6 and the inspection apparatus 1C.

The inspection apparatus 1C according to the third embodiment includes a pulse laser 2, an infrared sensor 3, a collimating lens 21, a dichroic mirror 22, a scanning mirror 23C, an objective lens 24, an imaging lens 25, a movement amount sensor 31, a control unit 11C, and image generation. 12C, a defect extraction unit 13C, and an input / output unit 14.

The movement amount sensor 31 is a sensor that detects the movement amount of the vehicle 6 in the Y direction. The movement amount sensor 31 generates a pulse signal c6 in response to detection of the movement amount of the vehicle 6 and supplies the pulse signal c6 to the control unit 11C. Various means can be applied as the movement amount sensor 31, but a rotary encoder is used in the third embodiment. The amount of movement in the Y direction due to the rotation of the wheel 6a is calculated by the rotary encoder. As another means of the movement amount sensor 31, the position of the vehicle 6 may be grasped using GPS or the like.

In the third embodiment, the controller 11C controls the whole including the scanning mirror 23C, the pulse laser 2, and the infrared sensor 3 using the pulse signal c6 of the movement amount sensor 31 as a reference clock.

The scanning mirror 23C is configured to be able to control the angle θ for scanning in the Y direction in accordance with an angle control signal c1 from the control unit 11C. A0 indicates an optical path that is emitted straight in the X direction with respect to the reference measurement point 5b in a state where the scanning mirror 23C is at the reference angle θ0.

[Measured point]
FIG. 9 schematically shows a state of measuring a plurality of measurement points 5b on a line in the Y direction of the measurement target surface 5a accompanying the movement of the vehicle 6 in the inspection apparatus 1C of the third embodiment. Examples of a plurality of measurement points 5b that are present in the Y direction on the measurement target surface 5a are shown as points P1, P2,. The positions of the vehicle 6 due to movement in the Y direction are indicated as Y1, Y2,. For example, the position Y1 corresponds to the position of the point P1.

In the third embodiment, as shown in FIG. 9, a plurality of measurement points 5b {P1, P2,...} With a predetermined interval on the line in the Y direction of the measurement surface 5a are objects to be measured and inspected. k1 represents the distance between the end of the inspection device 1C on the side surface of the vehicle 6 and the measured surface 5a. k2 indicates an interval between adjacent measurement points 5b on the line in the Y direction of the measurement surface 5a.

When the inspection apparatus 1C measures one point to be measured 5b during movement, the laser beam is irradiated a plurality of times by switching the state of the angle θ of the scanning mirror 23C with respect to the one point to be measured. Control to measure the difference. For example, for the point P1, the temperature difference is measured five times depending on whether or not the laser beam is irradiated five times as in A11 to A15. A11 is the optical path when the angle θ is the maximum positive angle (θa), A13 is the optical path when the angle θ is the reference angle θ0, and A15 is the maximum negative direction angle (θ). The optical path in the state of θb) is shown. Similarly, the temperature difference is measured a plurality of times for the other points P2 and the like.

[control method]
FIG. 10 shows a timing chart of the control by the inspection apparatus 1C of the third embodiment. The times indicated by E1 and E2 indicate the times of multiple measurements related to one measured point 5b, respectively.

(A) shows the pulse 1001 of the movement amount sensor 31 corresponding to the signal c6. The control unit 11C uses the pulse 1001 of the movement amount sensor 31 of (a) as a reference clock, and (b) oscillation and irradiation presence / absence of the pulse laser 2, (c) detection and readout of the infrared sensor 3, (d) The switching of the angle θ of the scanning mirror 23C is controlled. In FIG. 10, the pulses 1001 of the movement amount sensor 31 in FIG. 10A are shown at regular intervals, but in actuality, they occur at irregular intervals according to the speed change of the vehicle 6.

(B) shows control of the oscillation and irradiation (ON) and absence (OFF) of the pulse laser 2. Reference numeral 1002 denotes a pulse in an ON state. The control pulse 1002 of the pulse laser 2 in (b) is controlled to synchronize with the third pulse 1001 in (a).

(C) shows detection and readout control of the infrared sensor 3. Reference numeral 1003 denotes a pulse corresponding to the OFF state of (b), and reference numeral 1004 denotes a pulse corresponding to the ON state pulse 1002 of (b). The

control pulses

1003 and 1004 of the infrared sensor 3 in (c) are controlled so as to be synchronized with the first and third pulses 1001 in (a). As in the first embodiment, the infrared sensor 3 continuously detects the infrared rays generated in the two states of non-irradiation (OFF) and existence (ON) of the pulse laser 2.

(D) shows a signal 1005 for controlling the angle θ of the scanning mirror 23C. The signal 1005 is included in the angle control signal c1. The signal 1005 for controlling the angle θ of the scanning mirror 23C in (d) is controlled so as to be synchronized with the second pulse 1001 in (a). During the time E1 indicated by the times t1 to t2, the scanning angle θ is switched in five states between the maximum (θa) and the minimum (θb) for one point to be measured 5b, for example, the point P1. Similarly, at the time E2 indicated by the next times t3 to t4, the scanning angle θ is switched in five states for one point of the next measured point 5b in the Y direction, for example, the point P2. Reference numeral 1010 denotes a unit amount for increasing or decreasing the angle θ.

By the control as shown in FIG. 10, the focused light a4 that is the irradiation light of the pulse laser 2 in FIG. 8 is traveled for a certain period while the vehicle 6 is traveling, and the same measured point 5b on the measured surface 5a of the object 5. The scanning is controlled so as to continue irradiation. For example, at the time E1, the focused light a4 by the five pulses 1002 of (b) is irradiated to the point P1, and a state of presence / absence of five irradiations occurs. Then, in the infrared sensor 3 of (c), five temperature differences d1 to d5 are obtained from ten measured values s1 to s10, and a temperature difference v1 of the average values thereof is obtained.

The image generation unit 12C uses the signal c6 of the movement amount sensor 31 and the detection and readout signal c3 of the infrared sensor 3 for a plurality of measurement points 5b on the line of the measurement target surface 5a, for example, the points P1 and P2. Then, the process of calculating the temperature difference distribution is performed. The image generation unit 12C grasps the position of the measurement target point 5b from the movement amount detected by the movement amount sensor 31 or the position information of the vehicle 6 that can be calculated from the movement amount. The image generation unit 12C calculates a temperature difference at the measurement point 5b for each measurement point 5b on the measurement target surface 5a from the difference between the measurement values obtained by the infrared sensor 3 when the laser light is irradiated or not. A plurality of temperature differences are calculated from the values, and a temperature difference based on an average value thereof is calculated. Then, the image generation unit 12C generates an image, a graph, or the like including a temperature difference distribution at the plurality of measurement points 5b on the measurement target surface 5a.

FIG. 4B shows an example of partial data of the temperature difference distribution by the image generation unit 12C and the defect determination processing by the defect extraction unit 13C in the third embodiment. Reference numeral 411 indicates an allowable range as setting information for defect determination. A point D indicated by 412 is smaller than the threshold value h1 and outside the allowable range 411. A point F indicated by 413 is larger than the threshold value h2 and outside the allowable range 411. The defect extraction unit 13 C compares the temperature difference value with a threshold value, and determines that the defect or deterioration is present if it is outside the allowable range 411. The point D determined to be defective indicates that there is a high possibility of peeling near the point because the temperature difference and stress fluctuation are smaller than the threshold value, and there is a high possibility of cracking near the point F. Represents.

[Effects]
As described above, the inspection apparatus 1 C according to the third embodiment has a configuration that controls the angle θ of the scanning mirror 23 C while moving with the vehicle 6 and grasping the movement amount with the movement amount sensor 31. Thus, in the third embodiment, the temperature difference is measured a plurality of times for each measurement point 5b on the measurement target surface 5a of the fixed object 5. When the deflection control by the scanning mirror 23 is not performed, the measurement is performed once per one point to be measured 5b. On the other hand, since the third embodiment performs measurement a plurality of times per point, the temperature difference at the measurement point can be measured with higher accuracy than when the deflection control by the scanning mirror 23 is not performed. . As a result, it is possible to detect defects such as peeling and cracks in the target object 5 and signs thereof with high accuracy. According to the third embodiment, it is suitable for an application in which the surface of the object 5 is observed at a fixed point, and a structure such as a tunnel wall surface can be efficiently measured and inspected while moving by the vehicle 6.

As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

In the present embodiment, the case where the defect extraction unit is provided in the inspection apparatus has been described, but when there is no need to perform defect extraction in real time or when the amount of data is large and processing requires time, The defect extraction unit may be provided outside the inspection apparatus.

The present invention is applicable to a technique for inspecting the state of defects, deterioration, etc. for various structures including social infrastructure such as buildings, bridges, and tunnels.

DESCRIPTION OF SYMBOLS 1A, 1B, 1C ... Inspection apparatus, 2 ... Pulse laser, 3 ... Infrared sensor, 4 ... Infrared camera, 5 ... Object, 5a ... Measuring surface, 5b, 5c, 5d ... Measuring point, 6 ... Vehicle, 10 ... oscillator, 11A, 11B, 11C ... control unit, 12A, 12B, 12C ... image generation unit, 13A, 13B, 13C ... defect extraction unit, 14 ... input / output unit, 21 ... collimating lens, 22, 27 ... dichroic mirror, 23, 23B, 23C ... scanning mirror, 24 ... objective lens, 25 ... imaging lens, 28 ... telephoto lens, 29 ... reflection mirror, 31 ... movement amount sensor.

Claims

A laser unit that irradiates the measurement point on the surface of the object with laser light in at least two states of irradiation;
An optical system including a scanning mirror for scanning the surface of the object in at least a first direction with respect to the irradiation of the laser light;
An infrared sensor for detecting at least one infrared ray generated from a measurement point on the surface of the object by irradiation with the laser beam;
Infrared detection of the infrared sensor is performed when the laser light irradiation is in two states, and a temperature difference that is a difference between infrared detection signals in the two states is measured for each measurement point. A control unit for controlling the presence or absence of laser light irradiation of the laser unit, the angle of the scanning mirror, and the detection timing of infrared rays of the infrared sensor so as to be performed a plurality of times;
An image generation unit that generates an image including a temperature difference distribution of each of a plurality of measurement points in a region of the surface of the object based on the measured value of the temperature difference and the angle of the scanning mirror;
An infrared inspection apparatus.
The infrared inspection apparatus according to claim 1,
An oscillator that generates a reference clock; and
An objective lens for condensing the laser beam at a measurement point of the object;
An imaging lens that forms an image of the infrared sensor and the measurement point of the object in a conjugate relationship in combination with the objective lens;
A wavelength separation mirror for wavelength-separating laser light for irradiating the object and infrared light from the object;
Have
The said control part is an infrared rays inspection apparatus which controls the detection timing of the infrared rays of the infrared sensor of the said laser beam irradiation angle, the said scanning mirror, and the said infrared sensor based on the said reference clock.
The infrared inspection apparatus according to claim 1,
The scanning mirror has a first angle for scanning the surface of the object in the first direction and a second angle for scanning in the second direction with respect to the irradiation of the laser light,
The said image generation part is an infrared rays inspection apparatus which produces | generates the image containing distribution of the temperature difference of the several to-be-measured point in the area | region of the two-dimensional surface of the surface of the said target object.
In the infrared inspection apparatus according to any one of claims 1 to 3,
The infrared inspection apparatus further includes a defect extraction unit that determines and extracts a defect or a deteriorated portion using an image of the temperature difference distribution.
A laser unit that irradiates the measurement point on the surface of the object with laser light in at least two states of irradiation;
An optical system including a scanning mirror for scanning the surface of the object in at least a first direction with respect to the irradiation of the laser light;
An infrared camera that captures an image by detecting an infrared ray generated from a measurement point on the surface of the object by irradiation of the laser beam in a region of a line or a surface;
In a unit of image of the infrared camera, the laser unit controls the laser beam to be in a non-irradiation state, and the infrared camera detects the infrared ray in the non-irradiation state. The laser beam of the laser unit is controlled so as to capture an image in two states, a second image in which infrared light is detected by the infrared camera when the laser light is controlled to be in a state with irradiation. A control unit that controls the presence or absence of irradiation, the angle of the scanning mirror, and the timing of infrared detection of the infrared camera;
Temperature difference due to difference between a measurement value obtained by detecting the infrared ray when the first image is not irradiated and a measurement value obtained by detecting the infrared ray when the second image is irradiated An image generation unit that generates an image including a distribution of temperature differences of a plurality of measurement points in a line or surface area of the surface of the object based on the measured value;
An infrared inspection apparatus.
The infrared inspection apparatus according to claim 5,
An objective lens for condensing the laser beam at a measurement point of the object;
An imaging lens for imaging the infrared camera and the measurement point of the object in a conjugate relationship;
A wavelength separation mirror for wavelength-separating laser light for irradiating the object and infrared light from the object;
Have
The control unit controls the presence / absence of laser light irradiation of the laser unit, the angle of the scanning mirror, and the detection timing of infrared light of the infrared camera, based on the readout signal of the image unit from the infrared camera. Infrared inspection device.
The infrared inspection apparatus according to claim 5,
The scanning mirror has a first angle for scanning the surface of the object in the first direction and a second angle for scanning in the second direction with respect to the irradiation of the laser light,
The said image generation part is an infrared rays inspection apparatus which produces | generates the image containing distribution of the temperature difference of the several to-be-measured point in the area | region of the two-dimensional surface of the surface of the said target object.
The infrared inspection apparatus according to any one of claims 5 to 7,
The infrared inspection apparatus further includes a defect extraction unit that determines and extracts a defect or a deteriorated portion using an image of the temperature difference distribution.
An infrared inspection device mounted on a moving body,
A sensor unit for detecting a moving amount or position of the moving body;
A laser unit that irradiates a measurement point on the surface of a fixed object with laser light in at least two states;
An optical system including a scanning mirror for scanning in at least a first direction in order to irradiate a plurality of measurement points on the surface of the object with respect to irradiation of the laser light;
An infrared sensor for detecting at least one infrared ray generated from a measurement point on the surface of the object by irradiation with the laser beam;
The two states while detecting the infrared rays of the infrared sensor in the two states of presence / absence of irradiation of the laser light and switching the angle of the scanning mirror for each of a plurality of measurement points on the surface of the object The detection of the sensor unit, the presence or absence of laser light irradiation of the laser unit, the angle of the scanning mirror, and the infrared sensor A control unit that controls the timing of infrared detection;
Based on the detection information of the sensor unit and the measured value of the temperature difference, a calculation unit that calculates a temperature difference distribution for each of a plurality of measurement points on the surface of the object;
An infrared inspection apparatus.
The infrared inspection apparatus according to claim 9, wherein
An objective lens for condensing the laser beam at a measurement point of the object;
An imaging lens that forms an image of the infrared sensor and the measurement point of the object in a conjugate relationship in combination with the objective lens;
A wavelength separation mirror for wavelength-separating laser light for irradiating the object and infrared light from the object;
Have
The control unit controls the oscillation of the laser beam of the laser unit, the angle of the scanning mirror, and the detection timing of the infrared sensor, based on the pulse of the detection signal of the movement amount or position by the sensor unit. Infrared inspection device.
In the infrared inspection apparatus according to claim 9 or 10,
The infrared inspection apparatus further includes a defect extraction unit that determines and extracts a defect or a deteriorated portion using the temperature difference distribution.