Laser ultrasound inspection equipment, display devices, electronic equipment and mobile devices

Abstract

To provide a laser ultrasonic inspection device with a small number of parts, easy miniaturization, and excellent portability, as well as a display device, electronic device, and mobile body equipped with such a laser ultrasonic inspection device. [Solution] A laser ultrasound inspection apparatus comprising a first laser light source that irradiates pulsed first laser light, a laser interferometer that detects the vibration of a subject using second laser light, an imaging unit that images the irradiation position of the first laser light and the subject, and a housing, wherein the laser interferometer has a vibrator-type optical modulator that modulates the frequency of the second laser light using a vibrating element, and a photodetector that receives interference light between the second laser light that has passed through the subject and the second laser light that has passed through the vibrator-type optical modulator, the vibrating element is a signal source for a reference signal, the first laser light source emits first laser light based on the reference signal, and the imaging unit performs imaging based on the reference signal.

Description

Technical Field

[0006] ,

[0001] The present invention relates to a laser ultrasonic inspection device, a display device, an electronic device, and a moving body.

Background Art

[0002] Patent Document 1 discloses a laser ultrasonic flaw detection method in which pulsed laser light for generating ultrasonic waves is irradiated onto a reflection diaphragm to generate ultrasonic waves on the reflection diaphragm, the generated ultrasonic waves are transmitted to a specimen, and ultrasonic waves reflected from a defective location of the specimen are received by the reflection diaphragm, and vibrations of the reflection diaphragm generated at this time are detected by laser light for ultrasonic wave detection.

[0003] Further, Patent Document 2 discloses that in a laser ultrasonic inspection device, laser beams are irradiated onto a specimen to generate ultrasonic waves, and vibrations of the specimen caused by the generated ultrasonic waves are detected by a laser interferometer. According to such a laser ultrasonic inspection device, the distance resolution when determining the defective position of the specimen can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventional laser ultrasonic inspection devices have a large number of components and are difficult to miniaturize. For this reason, conventional laser ultrasonic inspection devices have poor portability, and for example, it is not assumed that they can be held by hand to inspect a specimen.

[0006] Therefore, the challenge is to create a laser ultrasonic inspection device with a small number of parts, that is easy to miniaturize, and that is highly portable. [Means for solving the problem]

[0007] A laser ultrasonic inspection apparatus according to an application example of the present invention is: A first laser light source that irradiates the subject with pulsed first laser light, A laser interferometer that detects vibrations of the subject caused by ultrasound induced in the subject by irradiation with the first laser beam using a second laser beam, The imaging unit performs imaging of the irradiation position of the first laser beam and the subject, A housing that houses the first laser light source, the laser interferometer, and the imaging unit, Equipped with, The aforementioned laser interferometer is A second laser light source that irradiates the subject with the second laser light, A vibrator-type optical modulator that modulates the frequency of the second laser light using a vibrating element, A photodetector receives interference light between the second laser light that has passed through the subject and the second laser light that has passed through the oscillator-type optical modulator, and outputs a received signal. It has, The aforementioned vibrating element is a signal source for a reference signal, The first laser light source emits the first laser light based on the reference signal, The imaging unit performs imaging based on the reference signal.

[0008] A display device according to an application example of the present invention is A laser ultrasonic inspection apparatus according to an application example of the present invention, A display unit that displays a distribution map of defects detected by the laser ultrasonic inspection device, It is equipped with.

[0009] The electronic device according to an example of the application of the present invention is The present invention includes a laser ultrasonic inspection apparatus according to an example of its application.

[0010] The mobile object according to the application example of the present invention includes a laser ultrasonic inspection device according to the application example of the present invention.

Brief Description of Drawings

[0011] [Figure 1] It is a block diagram showing a schematic configuration of a laser ultrasonic inspection device according to the first embodiment. [Figure 2] It is an example of a circuit diagram of a frequency converter including an n - bit counter. [Figure 3] It is a timing chart showing an example of a reference signal input to the signal processing unit, displacement calculated from the received light signal, laser detection signal, and imaging control signal. [Figure 4] It is a schematic diagram showing that the optical axis of the second laser beam is inclined at a deviation angle δ from a reference line parallel to the optical axis of the first laser beam. [Figure 5] It is a schematic diagram showing an example in which the optical axes of the first laser beam and the second laser beam are coaxially aligned using a coaxial optical system. [Figure 6] It is an example of a composite image when the object to be inspected is a bottle. [Figure 7] It is a schematic diagram showing the propagation of ultrasonic waves induced when the first laser beam is irradiated on two different locations on the surface of the object to be inspected. [Figure 8] It is an example of a scanning trajectory when the irradiation position of the first laser beam is scanned on the object to be inspected, and an example of a defect distribution diagram obtained by mapping the length of the elapsed time on the scanning trajectory by replacing it with the density of color. [Figure 9] It is a schematic diagram showing a schematic configuration of a laser ultrasonic inspection device according to the second embodiment. [Figure 10] It is a schematic diagram showing a schematic configuration of a laser ultrasonic inspection device according to the third embodiment. [Figure 11] It is a graph showing the waveform of the displacement of the object to be inspected accompanying vibration. [Figure 12]The figure shows an example of a scanning trajectory when the irradiation position of the first laser beam is scanned on a subject, and an example of a defect distribution map obtained by mapping the frequency analysis results on the scanning trajectory by replacing them with color density. [Figure 13] It is a schematic diagram showing a schematic configuration of a display device according to the fourth embodiment. [Figure 14] It is a perspective view showing a state of inspecting a subject using the display device shown in FIG. 13. [Figure 15] The figure shows an example of a defect distribution map displayed on the display unit shown in FIG. 13, and a figure showing the subject seen through the display unit superimposed. [Figure 16] It is an example of a defect distribution map displayed on the display unit shown in FIG. 13. [Figure 17] It is a schematic diagram showing a schematic configuration of an electronic device according to the fifth embodiment. [Figure 18] It is a schematic diagram showing a schematic configuration of an electronic device according to the fifth embodiment. [Figure 19] It is a schematic diagram showing a schematic configuration of a moving body according to the sixth embodiment. [Figure 20] It is a schematic diagram showing a schematic configuration of a moving body according to the sixth embodiment. [Figure 21] It is a schematic diagram showing a schematic configuration of a moving body according to the sixth embodiment. [Figure 22] It is a block diagram showing a schematic configuration of a conventional laser ultrasonic inspection device.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a laser ultrasonic inspection device, a display device, an electronic device, and a moving body according to the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

[0013] 1. Prior Art First, the prior art will be described.

[0014] FIG. 22 is a block diagram showing a schematic configuration of a conventional laser ultrasonic inspection device 9. The laser ultrasound inspection apparatus 9 shown in Figure 22 comprises a pulsed laser irradiation unit 91 and a vibration detection unit 93 (laser interferometer).

[0015] The pulsed laser irradiation unit 91 includes a laser light source 912, an amplifier 914, a voltage-current converter 916, a signal generator 918, and a photodiode 922.

[0016] The signal generator 918 generates a pulse control signal Sd. The voltage-to-current converter 916 converts the pulse control signal Sd, which is a pulsed voltage signal, into a current signal. The amplifier 914 amplifies the current signal and supplies it to the laser light source 912. The pulse laser irradiation unit 91 then irradiates the test subject 90 with laser light L91 emitted from the laser light source 912. This induces ultrasonic waves US in the test subject 90. The generated ultrasonic waves US propagate through the test subject 90, and if there is a defect def within the test subject 90, it is reflected there and reaches the surface. The ultrasonic waves US that reach the surface induce surface vibrations VB. In addition, the photodiode 922 receives a portion of the laser light L91 and generates a laser detection signal S1.

[0017] The vibration detection unit 93 is a laser interferometer and includes an acousto-optic modulator 932 (AOM), a laser light source 934, a photodiode 936, a signal generator 938, and a signal processing unit 95.

[0018] The signal generator 938 generates a drive signal Sa necessary for the operation of the acousto-optic modulator 932, and a reference signal Ss which serves as the time reference for signal processing in the signal processing unit 95. The vibration detection unit 93 irradiates the subject 90 with laser light L92 emitted from the laser light source 934. As a result, the laser light L92 undergoes a Doppler shift due to the vibration VB of the surface. The Doppler-shifted laser light L92 and the laser light L92 that has passed through the acousto-optic modulator 932 are then received by the photodiode 936, which outputs a received signal S2. By measuring this Doppler shift using the interference effect of light, the vibration VB is electrically detected.

[0019] The signal processing unit 95 calculates the elapsed time Δt from the emission of the laser beam L91 until the detection of vibration VB, based on the laser detection signal S1 output from the photodiode 922, the light reception signal S2 output from the photodiode 936, and the reference signal Ss output from the signal generator 938. The elapsed time Δt reflects the position of the reflection point that reflects the ultrasonic wave US. Based on the elapsed time Δt, the signal processing unit 95 determines the presence and location of a defect def.

[0020] However, the signal generator 938 in the vibration detection unit 93 increases the number of components in the laser ultrasonic inspection device 9. In particular, optical modulators such as the acousto-optic modulator 932 (AOM) and the electro-optic modulator (EOM) (not shown) are large and consume a lot of power. For this reason, the signal generator 938 that supplies the drive signal Sa to them also inevitably increases in the number of components and size, making it difficult to miniaturize conventional laser ultrasonic inspection devices 9 and resulting in poor portability.

[0021] Therefore, in each embodiment described later, a vibrator-type optical modulator using a vibrating element is provided to reduce the number of parts in the vibration detection unit (laser interferometer), miniaturize it, and reduce power consumption. This makes it possible to realize a laser ultrasonic inspection device that is easy to miniaturize and highly portable.

[0022] 2. First Embodiment Next, a laser ultrasound inspection apparatus according to the first embodiment will be described. Figure 1 is a block diagram showing the schematic configuration of the laser ultrasonic inspection apparatus 1 according to the first embodiment.

[0023] The laser ultrasonic inspection device 1 shown in Figure 1 comprises a head unit 5 and an inspection control unit 6. The head unit 5 is portable and has a size and weight that allows it to be moved to any desired position, for example, by being grasped by an operator. The inspection control unit 6 is, for example, fixed in any desired position. Wired or wireless communication is possible between the head unit 5 and the inspection control unit 6. The laser ultrasonic inspection device 1 shown in Figure 1 inspects the object 10 by detecting the presence and location of defects def contained in the object 10.

[0024] 2.1. Overview of the Head Unit The head unit 5 shown in Figure 1 includes a pulse laser irradiation unit 11, a vibration detection unit 13, an imaging unit 20, and a housing 52.

[0025] The pulsed laser irradiation unit 11 is located inside the housing 52. The pulsed laser irradiation unit 11 includes a first laser light source 112, an amplifier 114, a voltage-current converter 116, and a frequency converter 118. In the pulsed laser irradiation unit 11, the first laser light source 112 emits pulsed first laser light L11 based on the pulse control signal Sd output from the frequency converter 118. The pulsed first laser light L11 emitted from the first laser light source 112 is then irradiated onto the subject 10. This induces ultrasonic waves US in the subject 10. The generated ultrasonic waves US propagate radially within the subject 10, and if there is a defect def within the subject 10, it is reflected there and reaches the surface. The ultrasonic waves US that reach the surface induce vibrations VB accompanied by surface displacement.

[0026] The vibration detection unit 13 is located inside the housing 52. The vibration detection unit 13 is a laser interferometer and includes a vibrator-type optical modulator 132 using a vibrating element 130, a second laser light source 134, a photodiode 136 (photodetector), and a signal processing unit 15. The vibration detection unit 13 irradiates the subject 10 with a second laser beam L12 emitted from the second laser light source 134. The irradiated second laser beam L12 undergoes a Doppler shift due to the vibration VB of the surface of the subject 10. The Doppler-shifted second laser beam L12 is then received by the photodiode 136. The vibration VB is electrically detected by measuring this Doppler shift using the interference effect of the second laser beam L12 and the optical heterodyne method.

[0027] Specifically, the second laser beam L12 emitted from the second laser light source 134 is split into two by, for example, an optical splitter (not shown), one of which is incident on the oscillator-type optical modulator 132, and the other is incident on the test subject 10. In the oscillator-type optical modulator 132, the frequency of the second laser beam L12 is modulated, and a reference light containing the modulated signal is generated. Also, in the test subject 10, the second laser beam L12 undergoes a Doppler shift, and an object light containing a surface vibration signal is generated. These reference light and object light are interfered with and received by the photodiode 136. As a result, the photodiode 136 outputs a received signal S2 containing the modulated signal and the surface vibration signal. In the signal processing unit 15, the surface vibration signal is demodulated from the received signal S2, and the displacement and displacement velocity of the surface of the test subject 10 are calculated.

[0028] The transducer-type optical modulator 132 uses the vibration of the vibrating element 130 to apply a modulation signal to the second laser beam L12 and generates a reference signal Ss using the vibrating element 130 as a signal source. The transducer-type optical modulator 132 includes a vibrating element oscillation circuit (not shown) that causes the vibrating element 130 to oscillate. Since the vibrating element oscillation circuit can be constructed with a small number of components, the reference signal Ss can be generated while avoiding a significant increase in the number of components. Furthermore, since the vibration of the vibrating element 130 can be oscillated at a low voltage, the power consumption of the vibrating element oscillation circuit can be kept low. For this reason, the laser ultrasonic inspection device 1 can operate not only with an external power supply but also with an internal power supply such as a primary battery or secondary battery located inside the housing 40. In addition, by having the transducer-type optical modulator 132, the conventional acousto-optic modulator 932 can be omitted. This allows for miniaturization and weight reduction of the head unit 5, and provides portability to the head unit 5.

[0029] The signal processing unit 15 acquires the laser detection signal S1 output from the frequency converter 118, the light reception signal S2 output from the photodiode 136, and the reference signal Ss output from the oscillator-type optical modulator 132. Based on these, it calculates the elapsed time Δt from the time the first laser beam L11 is emitted until the vibration VB is detected. The calculated elapsed time Δt is output to the inspection control unit 6.

[0030] The imaging unit 20 is located inside the housing 52. The imaging unit 20 captures the irradiation position of the first laser beam L11 and the subject 10. The imaging unit 20 includes an image sensor and an imaging control unit (not shown).

[0031] Examples of image sensors include CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor).

[0032] The imaging control unit, although not shown, includes a drive control circuit that controls the driving of the image sensor, a signal processing circuit that processes the signal output from the image sensor, and the like. The drive control circuit controls the timing of exposure start by the image sensor, the exposure time, etc. The imaging timing and exposure time are determined based on the reference signal Ss output from the oscillator-type optical modulator 132. The signal processing circuit performs the necessary processing on the signal output from the image sensor and generates an image. The image shows the irradiation position of the first laser beam L11 and the subject 10. Therefore, the generated image includes information Pi of the irradiation position of the first laser beam L11, as shown in Figure 1. The image including the irradiation position information Pi is output to the inspection control unit 6.

[0033] The reference signal Ss output from the transducer-type optical modulator 132 is input to the imaging unit 20, the signal processing unit 15, and the inspection control unit 6, and is used as a time reference for the operation of each unit. Therefore, the laser ultrasound inspection device 1 can omit the conventional signal generator 938. This allows for miniaturization and weight reduction of the head unit 5, and provides the head unit 5 with portability. Furthermore, by using the reference signal Ss as a basis, the synchronization process of the operation of each unit can be performed easily and accurately. As a result, the inspection accuracy of the subject 10 by the laser ultrasound inspection device 1 can be improved.

[0034] The housing 52 is a case that houses the pulse laser irradiation unit 11, vibration detection unit 13, imaging unit 20, etc. By providing the housing 52, the portability of the head unit 5 can be improved. In addition, the contents can be protected from external pressure and changes in the external environment.

[0035] The following describes in detail each part of the laser ultrasound examination device 1. 2.1.1. Pulsed laser irradiation section The pulsed laser irradiation unit 11 shown in Figure 1 emits a pulsed first laser beam L11 having a predetermined repetition frequency toward the subject 10.

[0036] The first laser light source 112 emits pulsed first laser light L11. Examples of the first laser light source 112 include Nd:YAG lasers, CO2 lasers, Er:YAG lasers, titanium-sapphire lasers, alexandrite lasers, ruby ​​lasers, dye lasers, fiber lasers, excimer lasers, and semiconductor lasers. Of these, semiconductor lasers are preferably used. Semiconductor lasers can contribute to miniaturization, weight reduction, and low power consumption of the first laser light source 112. Furthermore, semiconductor lasers can easily produce pulsed oscillations by direct modulation, and can emit pulsed first laser light L11 at low cost. In addition, the semiconductor laser may have a metal package such as a CAN package, a ceramic package, etc., to house the element, as needed.

[0037] The repetition frequency of the pulsed first laser beam L11 is not particularly limited, but is preferably 1 Hz or more and 1000 Hz or less.

[0038] The pulse energy of the pulsed first laser beam L11 is set appropriately according to the material of the subject 10 and is not particularly limited, but is preferably 1 μJ / pulse or more, and more preferably 10 μJ / pulse or more and 10 J / pulse or less. Furthermore, if the subject 10 is a hard object such as a concrete block or a metal block, it is preferable to select a high pulse energy of about 1 mJ / pulse, and if it is a soft object such as a resin, it is preferable to select a low pulse energy of about 1 μJ / pulse.

[0039] Amplifier 114 amplifies the current signal supplied to the first laser light source 112. Note that amplifier 114 may be provided only if necessary, and may be omitted if amplification is not required for driving the first laser light source 112.

[0040] The voltage-to-current converter 116 converts the voltage signal output from the frequency converter 118 into a current signal.

[0041] The frequency converter 118 receives a reference signal Ss output from the oscillator-type optical modulator 132. Based on the reference signal Ss, the frequency converter 118 generates a pulse control signal Sd. The pulse control signal Sd is converted into a current signal by the voltage-current converter 116 and supplied to the first laser light source 112 via the amplifier 114. Based on this current signal, the first laser light source 112 determines the repetition period of the pulses of the first laser light L11. The frequency converter 118 includes, for example, a frequency divider circuit that divides the frequency of the reference signal Ss by n, an n-ary counter, etc., where n is a positive integer.

[0042] Figure 2 is an example of a circuit diagram of a frequency converter 118 including an n-ary counter. The frequency converter 118 shown in Figure 2 has a first circuit 142 and a second circuit 144.

[0043] The first circuit 142 receives a reference signal Ss output from the oscillator-type optical modulator 132. The first circuit 142 has the function of counting the pulses of the reference signal Ss and outputting the count value. In addition, the pulse control signal Sd output from the second circuit 144 is input to the first circuit 142 as a reset signal R. The first circuit 142 has the function of resetting the count value to zero when the reset signal R is input.

[0044] The second circuit 144 receives the count value and the number base N as input. The number base N is set, for example, according to the repetition frequency of the first laser beam L11. When the count value is A and the number base N is B, the second circuit 144 has the function of outputting a pulse when A = B. This pulse becomes the pulse control signal Sd. As a specific example, if the frequency of the reference signal Ss is 5 MHz and the number base N = 50000, a pulse of the pulse control signal Sd is output when the count value reaches 50000. In this case, the frequency converter 118 downconverts the frequency of the reference signal Ss from 5 MHz to 100 Hz and outputs it as the pulse control signal Sd.

[0045] By using such a frequency converter 118, the conventional signal generator 918 can be omitted. Since the frequency converter 118 described above can be made up of relatively few components, it is possible to further reduce the number of components in the laser ultrasonic inspection device 1.

[0046] 2.1.2. Vibration Detection Unit As described above, the vibration detection unit 13 shown in Figure 1 detects surface vibrations VB occurring on the subject 10 and generates a received signal S2 including a modulation signal and a surface vibration signal. A laser interferometer, for example, disclosed in Japanese Patent Application Publication No. 2022-38156, is preferably used for the vibration detection unit 13. Since this laser interferometer is equipped with an optical modulator using a vibration element, it contributes to miniaturization, weight reduction, and low power consumption of the vibration detection unit 13.

[0047] An example of a vibrator-type optical modulator 132 using a vibrating element 130 is the optical modulator disclosed in Japanese Patent Application Publication No. 2022-38156. Examples of vibrating elements 130 include quartz crystal resonators, silicon resonators, ceramic resonators, etc. Furthermore, the quartz crystal resonator may be an AT resonator, a tuning fork type resonator, or any other type of resonator. Since these resonators utilize the mechanical resonance phenomenon, they have a high Q value and can easily stabilize their natural frequencies. Therefore, the signal-to-noise ratio (S / N ratio) of the modulation signal applied to the second laser beam L12 can be easily increased. In addition, by using a resonator with a high Q value as the vibrating element 130, the S / N ratio of the reference signal Ss generated by the vibrator-type optical modulator 132 can also be increased, and the S / N ratio of various signals based on the reference signal Ss can also be increased.

[0048] Examples of the second laser light source 134 include the laser light source disclosed in Japanese Patent Application Publication No. 2022-38156. By using a semiconductor laser such as a VCSEL (Vertical Cavity Surface Emitting Laser), further miniaturization of the vibration detection unit 13 can be achieved.

[0049] The photodiode 136 (light-receiving element) receives interference light from the reference light (second laser light L12 that has passed through the oscillator-type optical modulator 132) and the object light (second laser light L12 that has passed through the subject 10), and outputs a received signal S2.

[0050] The oscillator-type optical modulator 132 uses the vibrating element 130 to apply a modulation signal to the second laser beam L12.

[0051] Furthermore, as described above, the oscillator-type optical modulator 132 includes a vibration element oscillator circuit that generates a reference signal Ss using the vibration element 130 as a signal source (source vibration). Examples of vibration element oscillator circuits include inverter-type oscillator circuits and Colpitts-type oscillator circuits. These oscillator circuits can generate a reference signal Ss with high frequency stability by using a vibration element 130 with a high Q value for mechanical resonance. In addition, by using the vibration element 130 as a signal source, less power is required to generate the reference signal Ss, thus contributing to lower power consumption of the vibration detection unit 13. Note that "using the vibration element 130 as a signal source" means vibrating the vibration element 130 and utilizing an electrical signal of a predetermined frequency generated based on that vibration.

[0052] The signal processing unit 15 measures the elapsed time Δt from the time the first laser beam L11 is emitted until the vibration VB is detected, based on the laser detection signal S1, the light reception signal S2, and the reference signal Ss.

[0053] To realize the function of calculating the elapsed time Δt among the functions of the signal processing unit 15, for example, the pre-processing unit and demodulation unit disclosed in Japanese Patent Application Publication No. 2022-38156 are used. In the pre-processing unit, the received signal S2 is pre-processed based on the reference signal Ss, and in the demodulation unit, the surface vibration signal is demodulated from the pre-processed signal based on the reference signal Ss.

[0054] When the ultrasonic waves US generated by the irradiation of the first laser beam L11 are reflected by the defect def shown in Figure 1, vibrations VB are induced on the surface of the specimen 10. These vibrations VB cause changes in the displacement and displacement velocity of the surface of the specimen 10. The signal processing unit 15 detects the vibrations VB by demodulating the surface vibration signal to extract the changes in displacement and displacement velocity of the surface of the specimen 10. This allows for accurate, non-contact detection of the vibrations VB. The signal processing unit 15 then measures the elapsed time Δt from the emission of the first laser beam L11 until the detection of the vibrations VB. This elapsed time Δt reflects the propagation distance from the generation of ultrasonic waves US, through reflection by the defect def, to their arrival on the surface. The signal processing unit 15 can accurately measure the elapsed time Δt by using a reference signal Ss as a time reference. This elapsed time Δt can be calculated, for example, by counting the pulses of the reference signal Ss.

[0055] Furthermore, in this embodiment, the pulse control signal Sd output from the frequency converter 118 is input to the signal processing unit 15 as the laser detection signal S1. Therefore, in this embodiment, the conventional photodiode 922 can be omitted. Also, since the laser detection signal S1 is the same signal as the pulse control signal Sd, it accurately reflects the timing at which the first laser beam L11 is emitted. Consequently, the signal processing unit 15 can measure the elapsed time Δt more accurately.

[0056] Figure 3 is a timing chart showing an example of the reference signal Ss, the displacement d calculated from the received signal S2, the laser detection signal S1, and the imaging control signal St input to the signal processing unit 15.

[0057] The signal processing for displacement d and laser detection signal S1 shown in Figure 3 is performed (synchronously) based on a reference signal Ss. Specifically, the signal processing unit 15 measures, for example, the elapsed time Δt1 from the rising edge of pulse S11 of the laser detection signal S1 (the timing of the emission of the first laser beam L11) until displacement d1 is detected, based on the reference signal Ss. Similarly, the elapsed time Δt2 from the rising edge of pulse S12 (the timing of the emission of the first laser beam L11) until displacement d2 is detected is measured based on the reference signal Ss. This facilitates the synchronization of signal processing, allowing for easy and accurate measurement of elapsed times Δt1 and Δt2.

[0058] 2.1.3. Imaging Unit The imaging unit 20 captures images of the irradiation position of the first laser beam L11 and the subject 10.

[0059] The drive control circuit of the imaging unit 20 outputs an imaging control signal St shown in Figure 3 based on a reference signal Ss. The control element of the imaging unit 20 controls the exposure start timing and exposure time E based on the imaging control signal St. For example, Figure 3 shows that three exposure times E are set. The time other than the exposure time E is the non-exposure time NE. Specifically, the rising timings of the imaging control signals St1, St2, and St3 shown in Figure 3 are the exposure start timings, respectively. Also, the time from the rising to the falling of the imaging control signals St1, St2, and St3 is the exposure time E, respectively.

[0060] The timing of the exposure start is set to be before the rising edge of the laser detection signal S1 (before the emission of the first laser beam L11). In other words, the first laser light source 112 emits the first laser beam L11 after a predetermined time has elapsed since the imaging unit 20 started exposure. As a result, the first laser beam L11 is irradiated during the exposure time E, so that the irradiation position of the first laser beam L11 can be reliably captured in the image acquired by the image sensor. Although the timing of the exposure start and the timing of the irradiation of the first laser beam L11 may be simultaneous, it is preferable to set them as described above, taking into account the possibility of a time lag from the rising edge of the laser detection signal S1 until the image sensor stabilizes.

[0061] The exposure time E is set according to the irradiation time of the first laser beam L11, that is, according to the pulse width and pulse repetition period of the first laser beam L11. The image acquired in one exposure time E may record the irradiation positions for multiple pulses of the first laser beam L11, but preferably the irradiation position for one pulse of the first laser beam L11 is recorded. Therefore, it is preferable to quickly end the exposure as soon as the pulse S11 of the laser detection signal S1 shown in Figure 3 rises and the first laser beam L11 is emitted. This allows the irradiation position for one pulse to be recorded in the image and suppresses image blurring caused by movement of the irradiation position during the exposure time E.

[0062] In this embodiment, the emission of the first laser beam L11, the timing of the exposure start in the imaging unit 20, and the exposure time E are controlled based on a reference signal Ss (by counting the pulses of the reference signal Ss), as shown in Figure 3. Therefore, timing deviations are less likely to occur, and an image capturing the irradiation position of the first laser beam L11 can be reliably acquired. As a result, the inspection control unit 6, described later, can more accurately determine the irradiation position of the first laser beam L11 on the subject 10 based on this image. Consequently, the presence and location of defects def on the subject 10 can be detected more accurately. In other words, the inspection of the subject 10 can be performed reliably, and the inspection accuracy can be improved.

[0063] To achieve the exposure time E described above, the frame rate [fps] of the imaging unit 20 should be set higher than the repetition frequency [Hz] of the pulse of the first laser beam L11. The pulse width of the first laser beam L11 is, for example, about 10 [ns], and laser oscillation is stopped during times outside of the pulse width. In this case, the exposure time E can be arbitrarily set to a time longer than the pulse width of the first laser beam L11.

[0064] The imaging range of the imaging unit 20 is set to the range in which the examination of the subject 10 is performed, and also to include the irradiation position of the first laser beam L11.

[0065] The optical axes of the first laser beam L11 and the second laser beam L12 may be offset from each other, but it is preferable that they be parallel to each other. This allows the distance between the irradiation position of the first laser beam L11 and the irradiation position of the second laser beam L12 to remain constant, as shown in Figure 1, even when the head unit 5 is moved relative to the specimen 10. As a result, when calculating the position of the defect def from the elapsed time Δt, it is not necessary to make corrections due to changes in the distance between the irradiation positions, thus reducing the amount of computation.

[0066] It should be noted that the optical axes may be slightly non-parallel to each other. Figure 4 is a schematic diagram showing that the optical axis of the second laser beam L12 is tilted by an angle δ from the reference line DL, which is parallel to the optical axis of the first laser beam L11.

[0067] In Figure 4, the distance from the head unit 5 to the specimen 10 is SZ, and the optical axis of the second laser beam L12 is offset by an angle δ relative to the reference line DL. In this case, it is preferable that the offset width SX between the reference line DL and the irradiation position of the second laser beam L12 on the specimen 10 is 3% or less of the distance SZ. This ensures sufficient accuracy in detecting defects def, and as a result, the required assembly precision in the assembly of the laser ultrasonic inspection device 1 can be relaxed.

[0068] Furthermore, if the displacement width SX is 3% or less of the distance SZ, the displacement angle δ will be 1.7° or less. Therefore, when the optical axes are not parallel to each other, it is preferable that the displacement angle δ shown in Figure 4 is 1.7° or less. This makes it possible to realize a laser ultrasonic inspection device 1 that is easy to assemble while ensuring sufficient accuracy in detecting defects def.

[0069] In Figure 4, D is defined as the distance between the optical axis of the first laser beam L11 and the optical axis of the second laser beam L12 on the surface of the specimen 10. The distance D is not particularly limited, but is preferably between 0 mm and 50 mm. This makes it easier to improve the positional accuracy of the detected defect def.

[0070] Furthermore, when the distance D is 10 mm or less, it is preferable to make the wavelengths of the first laser beam L11 and the second laser beam L12 different, and it is more preferable to make the wavelengths different by 30 nm or more. This makes it possible to suppress a decrease in the accuracy of defect detection def even when the beams of the first laser beam L11 and the second laser beam L12 overlap.

[0071] Furthermore, if the distance D is 10 mm or less, a coaxial optical system may be used to make the optical axis of the first laser beam L11 and the optical axis of the second laser beam L12 coaxial.

[0072] Figure 5 is a schematic diagram showing an example in which the optical axis of the first laser beam L11 and the optical axis of the second laser beam L12 are made coaxial using a coaxial optical system.

[0073] The coaxial optical system shown in Figure 5 includes dichroic mirrors 31 and 32. Dichroic mirror 31 is positioned on the optical axis of the first laser beam L11 and transmits the first laser beam L11. Dichroic mirror 32 is positioned on the optical axis of the second laser beam L12 and reflects the second laser beam L12. The reflected second laser beam L12 is reflected by dichroic mirror 31 so as to coincide with the optical axis of the first laser beam L11. As a result, the optical axes of the first laser beam L11 and the second laser beam L12 are coaxial, making it possible to detect defects def even when the size of the sample 10 is small.

[0074] Furthermore, at the irradiation position of the second laser beam L12, the angle between the normal to the surface of the specimen 10 and the optical axis of the second laser beam L12 is not particularly limited, but is preferably set to 10° or less. In other words, it is preferable that the optical axis of the second laser beam L12 extends in a direction perpendicular to or close to perpendicular to the surface of the specimen 10. This allows the vibration detection unit 13 to receive the second laser beam L12 reflected by the specimen 10 with sufficient intensity. Also, even if the distance SZ from the head unit 5 to the specimen 10 changes, the distance D shown in Figure 4 does not change easily, so the amount of calculation required to calculate the location of the defect def can be reduced.

[0075] 2.1.4. Enclosure The size of the housing 52 is not particularly limited, but considering that it will be held by an operator, it is preferable that it fits within a 250 mm cube, and more preferably within a 200 mm cube. Furthermore, considering that it will be held with one hand, it is even more preferable that it fits within a 150 mm cube.

[0076] The housing 52 shown in Figure 1 includes a main body 522, a first ejection window 524, a second ejection window 526, and an imaging window 528.

[0077] The main body 522 has a rigid, box-like shape. The constituent materials of the main body 522 are not particularly limited and can be appropriately selected from, for example, metal materials, resin materials, etc.

[0078] The first emission window 524 is transparent so that the first laser beam L11 can be emitted to the outside. The first emission window 524 may be a through-hole formed in the main body 522, or it may be a transparent window material fitted into the through-hole.

[0079] The second ejection window 526 is transparent so that the second laser beam L12 can be ejected to the outside. The second laser beam L12 reflected by the subject 10 is incident on the inside of the housing 52 through the second ejection window 526. The second ejection window 526 may be a through-hole formed in the main body 522, or it may be a transparent window material fitted into the through-hole.

[0080] The first injection window 524 and the second injection window 526 may be integrated with each other, but preferably they are spaced apart as shown in Figure 1. This prevents the second laser light L12 reflected by the specimen 10 from returning to the first laser light source 112, and prevents the first laser light L11 reflected by the specimen 10 from entering the photodiode 136.

[0081] The imaging window 528 is transparent to visible light and infrared light, etc., so that imaging can be performed by the imaging unit 20. The imaging window 528 may be a through hole formed in the main body 522, or it may be a transparent window material fitted into the through hole.

[0082] By providing such a housing 52, the portability of the head unit 5 can be improved. In addition, the contents can be protected from external pressure and changes in the external environment. The first ejection window 524, the second ejection window 526, and the imaging window 528 may be provided as needed and may be omitted. In that case, a large through-hole or window material may be provided to encompass the first ejection window 524, the second ejection window 526, and the imaging window 528.

[0083] 2.2. Overview of the Inspection and Control Unit The inspection control unit 6 shown in Figure 1 includes an object recognition unit 62, a defect detection unit 64, and a storage unit 66.

[0084] The object recognition unit 62 performs object recognition processing on the image acquired by the imaging unit 20. The defect detection unit 64 acquires multiple images from the imaging unit 20 in which the irradiation positions of the first laser beam L11 and the second laser beam L12 on the subject 10 are different from each other. It also calculates the irradiation position on the subject 10 based on the multiple images. Then, it detects the defect def contained in the subject 10 based on the irradiation position and the elapsed time Δt mentioned above. The storage unit 66 stores the images acquired from the imaging unit 20.

[0085] In this embodiment, the inspection control unit 6 is located outside the housing 52, but the inspection control unit 6 may also be housed inside the housing 52. In this case, portability can be provided to both the head unit 5 and the inspection control unit 6.

[0086] 2.2.1.Object recognition part The object recognition unit 62 performs object recognition processing on the image acquired by the imaging unit 20. The object recognition processing involves recognizing the position of objects in the image. Specifically, it performs processes such as specific object detection using machine learning, pattern detection to detect patterns and characteristic shapes, and template matching based on similarity with a template image. As a result, the object recognition unit 62 can obtain the coordinates of the position of the subject 10 in the image. Based on these coordinates, the defect detection unit 64, described later, can calculate the relative irradiation position P(X,Y) of the first laser beam L11 and the second laser beam L12 on the subject 10.

[0087] Figure 6 shows an example of a composite image CI when the subject 10 is a bottle. A composite image CI is an image created by combining multiple images acquired by the imaging unit 20 while matching the position of the subject 10. The composite image CI shown in Figure 6 shows an image of the bottle as the subject 10, and a frame line FL indicating that the position of the subject 10 has been recognized. Furthermore, the composite image CI shown in Figure 6 is created by combining three images acquired by the imaging unit 20 while moving the head unit 5 relative to the subject 10. Therefore, this composite image CI includes beam images F1 of the first laser beam L11 and the second laser beam L12 extracted from the first image, beam images F2 of the first laser beam L11 and the second laser beam L12 extracted from the second image, and beam images F3 of the first laser beam L11 and the second laser beam L12 extracted from the third image.

[0088] Since the first laser beam L11 and the second laser beam L12 included in beam images F1, F2, and F3 have high brightness, the defect detection unit 64, described later, can accurately detect their irradiation positions. As a result, the defect detection unit 64 can calculate the relative irradiation positions P(X,Y) of the first laser beam L11 and the second laser beam L12 on the test subject 10.

[0089] Note that Figure 6 shows an example where the entire bottle, which is the subject 10, is captured. However, if the subject 10 is large, only a part of it may be captured. In this case, if any feature point is captured instead of the outline of the subject 10, the irradiation position P(X,Y) can be calculated based on that feature point.

[0090] The object recognition unit 62 may, if necessary, have a function to generate the composite image CI described above.

[0091] Furthermore, the object recognition unit 62 may be provided as needed. For example, if the relative size and position of the subject 10 with respect to the imaging unit 20 are constant, the position of the subject 10 in the image is also known, so the object recognition unit 62 may be omitted. Even without recognizing the position of the subject 10, the imaging unit 20 acquires an image including the irradiation position of the first laser beam L11, making it possible to retrospectively identify the irradiation position on the subject 10 based on the irradiation position captured in the image. On the other hand, by providing the object recognition unit 62, the position of the subject 10 in the image can be identified even when the relative size and position of the subject 10 with respect to the imaging unit 20 are not constant, thereby improving the convenience of the examination.

[0092] 2.2.2. Defect Detection Unit The defect detection unit 64 acquires multiple images from the imaging unit 20 in which the irradiation positions of the first laser beam L11 and the second laser beam L12 on the object 10 are different from each other. These multiple images are acquired, as described above, for example, by moving the head unit 5 relative to the object 10. The head unit 5 may be moved by a moving device (not shown), or by an operator holding the head unit 5 and moving it. In the multiple images acquired in this way, the beam images F1, F2, and F3 of the first laser beam L11 and the second laser beam L12 irradiated at different positions on the object 10 are individually captured, as shown in Figure 4. The defect detection unit 64 calculates the relative irradiation positions P(X,Y) of the first laser beam L11 and the second laser beam L12 on the object 10 from the relative positions of these beam images F1, F2, and F3.

[0093] Furthermore, if the optical axes of the first laser beam L11 and the second laser beam L12 are fixed and parallel or nearly parallel, then the relationship between their irradiation positions can be considered known. Therefore, it is sufficient for each image to show at least the irradiation position of the first laser beam L11, but it is preferable that the irradiation position of the second laser beam L12 is also shown.

[0094] Meanwhile, at the timing when beam images F1, F2, and F3 are captured, the signal processing unit 15 measures the elapsed time Δt corresponding to the position of each beam image F1. The defect detection unit 64 then acquires multiple datasets of irradiation position P(X,Y) and elapsed time Δt in the subject 10, and detects defects def in the subject 10 based on the acquired datasets. Since the position of the ultrasonic US reflection point is reflected in the elapsed time Δt, the presence and location of defects def can be determined based on the elapsed time Δt. An example of how to determine the location of defects def from multiple datasets is described below.

[0095] The difference between the elapsed time Δt1 and elapsed time Δt2 shown in Figure 3 reflects the relationship between the irradiation position of the first laser beam L11 and the position of the defect def shown in Figure 1, when the first laser beam L11 is irradiated at different positions on the subject 10. The first laser beam L11 is irradiated while changing the relative position of the head unit 5 with respect to the subject 10, and the elapsed time Δt is measured, while calculating the irradiation positions P(X,Y) of the first laser beam L11 and the second laser beam L12 on the subject 10. This makes it possible to identify the position of the defect def. A specific example is described below.

[0096] Figure 7 is a schematic diagram showing the propagation of ultrasonic waves US1 and US2 induced when the first laser beams L111 and L112 are irradiated at two different locations on the surface of the specimen 10. When the first laser beam L111 is irradiated, ultrasonic waves US1 propagate along numerous trajectories, including the trajectory shown in Figure 7. Some of these waves are reflected by defects def and reach the surface. The ultrasonic waves US1 that reach the surface are detected, for example, as surface displacement (vibration) by the second laser beam L12. Similarly, the first laser beam L112 induces ultrasonic waves US2 that propagate along numerous trajectories, including the trajectory shown in Figure 8. Some of these waves are reflected by defects def and reach the surface. The ultrasonic waves US2 that reach the surface are detected, for example, as surface displacement (vibration) by the second laser beam L12.

[0097] Figure 3 shows examples of the waveforms of displacement d1 originating from ultrasonic wave US1 reflected by defect def, and displacement d2 originating from ultrasonic wave US2 reflected by defect def. Since the first laser beams L111 and L112 are irradiated at different positions, the elapsed times Δt1 and Δt2 until displacements d1 and d2 are detected are also different, as shown in Figure 3. Therefore, the defect detection unit 64 has a function to determine the presence of defect def based on a preset reference value for the elapsed time Δt, for example, if the elapsed time Δt is less than or equal to the reference value. The defect detection unit 64 may also have a function to determine the presence or absence of defect def by other means.

[0098] The propagation velocities of ultrasonic waves US1 and US2 can be obtained in advance based on the material of the sample 10 or by actual measurement. Therefore, the propagation distance of ultrasonic waves US1 and US2 can be calculated from the elapsed times Δt1 and Δt2 and the propagation velocities. If ultrasonic wave US1 propagates at the calculated propagation distance, the defect def will be located somewhere on the ellipse e1 shown in Figure 7. Similarly, if ultrasonic wave US2 propagates at the calculated propagation distance, the defect def will be located somewhere on the ellipse e2 shown in Figure 7. Based on this principle, the location of the defect def in Figure 7 can be identified by irradiating the first laser beam L11 at three or more irradiation positions.

[0099] Therefore, as shown in Figure 6, if an image containing at least three beam images F1, F2, and F3 can be obtained, the defect detection unit 64 can identify the location of the defect def based on the above principle. Since such defect def detection can be performed non-destructively, the laser ultrasonic inspection device 1 enables non-destructive inspection of the object 10. In addition, the distribution of defects def can be obtained by scanning the head unit 5 in two dimensions.

[0100] Examples of constituent materials for the subject 10 include concrete, metal, resin, ceramics, and glass. Examples of defects def include voids, cracks, delamination, interfaces, foreign matter, and modified parts.

[0101] Furthermore, the defect detection unit 64 may have a function to create a defect distribution diagram that shows the distribution of defects def contained in the sample 10. This defect distribution diagram allows for a visual representation of the inspection results of the sample 10. This can help support the understanding of the inspection results.

[0102] Specifically, the defect detection unit 64 creates a defect distribution map using a dataset of irradiation position P(X,Y) and elapsed time Δt in the sample 10 as point cloud data.

[0103] Figure 8 shows an example of a scanning trajectory TR when scanning the irradiation position of the first laser beam L11 on the subject 10, and an example of a defect distribution map Id1 obtained by mapping the elapsed time Δt along the scanning trajectory TR to color intensity. Figure 8 also shows examples of the waveforms of the acquired displacement d at two locations with different color intensities in the defect distribution map Id1.

[0104] The scanning trajectory TR shown in Figure 8 is the trajectory when the irradiation position of the first laser beam L11 is moved back and forth in the Y-axis direction while being shifted in the X-axis direction. In addition, in the defect distribution diagram Id1 shown in Figure 8, the color density is lighter when the elapsed time Δt is relatively long, and darker when the elapsed time Δt is relatively short. By generating such a defect distribution diagram Id1, the presence, location, depth, etc., of defects def can be visually indicated.

[0105] The laser ultrasound inspection apparatus 1 shown in Figure 1 may include a display unit (not shown) for displaying the defect distribution map Id1 created as described above. Examples of display units include liquid crystal displays, organic EL displays, and image projection devices. The display unit may also display the image acquired by the imaging unit 20 overlaid on the defect distribution map Id1. This helps in understanding the correspondence between the location of the defect def and the subject 10.

[0106] 2.2.3.Storage section The storage unit 66 temporarily stores multiple images acquired from the imaging unit 22. This allows the irradiation positions of the first laser beam L11 and the second laser beam L12 on the subject 10 to be calculated while suppressing a temporary increase in the computational load of the defect detection unit 64. The functions of the storage unit 66 are realized by the memory described later.

[0107] 2.3. Hardware Configuration The functions of the signal processing unit 15, object recognition unit 62, and defect detection unit 64 are realized by hardware, for example, a CPU, memory, and an interface. Such hardware may include, for example, a microcontroller. The CPU is a Central Processing Unit. Examples of memory include any non-volatile memory (ROM), any volatile memory (RAM), or removable external memory. Examples of interfaces include digital input / output ports such as USB (Universal Serial Bus). The functions of the signal processing unit 15, object recognition unit 62, and defect detection unit 64 are realized by the CPU executing a program pre-loaded into memory. Alternatively, instead of, or in conjunction with, the CPU may use an FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), other integrated circuits, discrete components, etc., to realize these functions.

[0108] As described above, in this embodiment, the vibration of the vibration element 130 is used for optical modulation (modulation of the frequency of the second laser beam L12), demodulation of the surface vibration signal, generation of the pulse control signal Sd, control of imaging by the imaging unit 20, and measurement of the elapsed time Δt, thereby reducing the number of parts. The head unit 5 also has a housing 52 that accommodates the pulse laser irradiation unit 11, the vibration detection unit 13, and the imaging unit 20, etc. This makes it possible to realize a laser ultrasonic inspection device 1 that is easy to miniaturize and has excellent portability. In addition, by using the same reference signal Ss as a time reference, the synchronization of signal processing can be easily and accurately performed. This makes it possible to improve the inspection accuracy of the subject 10 by the laser ultrasonic inspection device 1.

[0109] 3. Second Embodiment Next, a laser ultrasound inspection apparatus according to the second embodiment will be described. Figure 9 is a schematic diagram showing the general configuration of the laser ultrasound inspection apparatus 1 according to the second embodiment.

[0110] The second embodiment will be described below, focusing on the differences from the first embodiment, and similar matters will be omitted from the description. In Figure 9, components similar to those in the first embodiment are denoted by the same reference numerals.

[0111] The laser ultrasonic inspection apparatus 1 according to the second embodiment is the same as the laser ultrasonic inspection apparatus 1 according to the first embodiment, except that it is configured to measure the thickness t10 of the object to be examined 10.

[0112] The inspection control unit 6 shown in Figure 9 has a thickness measuring unit 68 instead of the defect detection unit 64 shown in Figure 1. In the laser ultrasonic inspection apparatus 1 shown in Figure 9, when a first laser beam L11 is irradiated onto one side of the object to be inspected 10, and the induced ultrasonic wave US is reflected off the other side and then returns to the first side to induce a vibration VB, this vibration VB is detected by a second laser beam L12. In this case, the elapsed time Δt from the emission of the first laser beam L11 until the detection of the vibration VB reflects the thickness t10 of the object to be inspected 10. That is, when the propagation speed of the ultrasonic wave US is V, the thickness t10 can be calculated using the following equation (1). t10 = V·Δt / 2 (1)

[0113] It should be noted that equation (1) above is strictly true only when the optical axes of the first laser beam L11 and the second laser beam L12 are coaxial. Therefore, if they are not coaxial, correction should be made based on the distance between them and the propagation distance of the ultrasonic wave US calculated from the elapsed time Δt.

[0114] The calculation of the thickness t10 as described above can be performed in the thickness measurement unit 68. This allows the laser ultrasonic inspection device 1 to non-destructively inspect the thickness t10 of the sample 10.

[0115] Furthermore, by calculating the thickness t10 while changing the relative position of the head unit 5 with respect to the test subject 10, a thickness distribution map can be created in the thickness measurement unit 68. This can help support the understanding of the test results. In the second embodiment described above, the same effects as in the first embodiment can be obtained.

[0116] 4. Third Embodiment Next, a laser ultrasound inspection apparatus according to the third embodiment will be described. Figure 10 is a schematic diagram showing the general configuration of the laser ultrasound inspection apparatus 1 according to the third embodiment.

[0117] The third embodiment will now be described, focusing on the differences from the first embodiment, and similar aspects will be omitted. In Figure 10, components similar to those in the first embodiment are denoted by the same reference numerals.

[0118] The laser ultrasonic inspection apparatus 1 according to the third embodiment is the same as the laser ultrasonic inspection apparatus 1 according to the first embodiment, except that the signal processing unit 15 is configured to calculate the frequency of vibration VB based on a reference signal Ss.

[0119] The signal processing unit 15 shown in Figure 10 captures the displacement and displacement velocity generated on the surface of the test subject 10 in conjunction with the vibration VB. This allows for the detection of the vibration VB.

[0120] Figure 11 is a graph showing the waveform of the displacement of the subject 10 due to vibration VB. In Figure 11, the horizontal axis represents time, and the vertical axis represents the displacement of the subject 10.

[0121] In the graph shown in Figure 11, during the elapsed time Δt from the emission of the first laser beam L11 until the vibration VB is detected as a displacement on the surface of the test subject 10, almost no displacement is observed. On the other hand, after elapsed time Δt, the amplitude of the displacement increases. Based on this, the vibration VB can be detected.

[0122] The signal processing unit 15 shown in Figure 10 has the function of acquiring the time waveform of the displacement increased due to the vibration VB shown in Figure 11 and performing frequency analysis. Alternatively, the time waveform of the displacement velocity may be acquired instead of the time waveform of the displacement. Fast Fourier analysis can be used for the frequency analysis. The signal processing unit 15 generates the frequency analysis result fo through the frequency analysis. The frequency analysis result fo includes the intensity of each frequency component, i.e., resonance frequency information. Since the time waveform of the displacement is generated based on the reference signal Ss, a highly accurate frequency analysis result fo can be obtained.

[0123] Furthermore, in this embodiment, the defect detection unit 64 acquires multiple datasets of irradiation position P(X,Y) and frequency analysis result fo in the sample 10. Based on the acquired datasets, it detects defects def contained in the sample 10. Since the frequency analysis result fo reflects the unique frequency of the defect def, the presence and location of the defect def can be determined based on the frequency analysis result fo. This enables non-destructive inspection of the sample 10.

[0124] Furthermore, the defect detection unit 64 may have a function to create a defect distribution map using a dataset of irradiation position P(X,Y) and frequency analysis result fo in the subject 10 as point cloud data.

[0125] Figure 12 shows an example of a scanning trajectory TR when scanning the irradiation position of the first laser beam L11 on the subject 10, and an example of a defect distribution map Id2 obtained by mapping the frequency analysis result fo on the scanning trajectory TR by replacing it with color density. Figure 12 also shows examples of the waveforms of the acquired frequency analysis result fo for two locations with different color densities in the defect distribution map Id2.

[0126] In the defect distribution map Id2 shown in Figure 12, for example, if the intensity at a frequency around 2 kHz is below a predetermined threshold, the color density is lighter, and if the intensity is above the predetermined threshold, the color density is darker. By generating such a defect distribution map Id2, it is possible to visually indicate the presence and location of defects def, resonant frequency information, etc. In the third embodiment described above, the same effects as in the first embodiment can be obtained.

[0127] Furthermore, in this embodiment, the vibration of the vibration element 130 is used for optical modulation, demodulation of the surface vibration signal, generation of the pulse control signal Sd, control of imaging by the imaging unit 20, and generation of time waveforms of displacement and displacement velocity, thereby reducing the number of parts.

[0128] 5. Fourth Embodiment Next, as a fourth embodiment, a display device equipped with a laser ultrasonic inspection device will be described. Figure 13 is a schematic diagram showing the general configuration of the display device 71 according to the fourth embodiment.

[0129] The following describes the fourth embodiment, focusing on the differences from the first embodiment, and omitting explanations of similar matters. In Figures 13 and 14, components similar to those in the first embodiment are denoted by the same reference numerals.

[0130] The display device 71 shown in Figure 13 is a head-mounted display and comprises a laser ultrasound inspection device 1 and a display unit 72. The display unit 72 has a transmissive display panel and is configured to display the aforementioned defect distribution maps Id1, Id2, etc., and to allow the user to see through to the outside world. In addition, it may be configured to display images acquired by the imaging unit 20 or object recognition results by the object recognition unit 62, etc., as needed.

[0131] The display device 71 is attached to a person's head. This positions the display unit 72 directly in front of the eyes.

[0132] Furthermore, the display device 71 shown in Figure 13 includes a mounting section 73. The mounting section 73 consists of pads, belts, etc., that secure the laser ultrasound inspection device 1 and the display unit 72 to a person's head.

[0133] In the display device 71 shown in Figure 13, the head unit 5 of the laser ultrasound inspection device 1 is positioned on the surface (the surface facing forward from the viewer's perspective). As a result, the first emission window 524, the second emission window 526, and the imaging window 528 are exposed on the surface.

[0134] Figure 14 is a perspective view showing the inspection of the subject 10 using the display device 71 shown in Figure 13. The subject 10 shown in Figure 14 is shaped like a rectangular parallelepiped, and one of its outer surfaces is designated as the front 101. In Figures 14 to 16, the three mutually orthogonal axes are designated as the a-axis, b-axis, and c-axis. The front 101 is the surface perpendicular to the b-axis.

[0135] When an operator wearing the display device 71 looks directly at the front 101 and scans their head along the front 101, the irradiation position of the first laser beam L11 is also scanned. This allows the subject 10 to be examined along the front 101.

[0136] Figure 15 shows an example of the defect distribution diagram Id3 displayed on the display unit 72 shown in Figure 13, and the subject 10 as seen through the display unit 72, superimposed on the diagram.

[0137] The defect distribution diagram Id3 shown in Figure 15 visually displays the defect distribution di in the in-plane direction (ac-plane direction) of the front view 101. By displaying this defect distribution diagram Id3 overlaid on the actual image of the subject 10, an intuitive understanding of the defect distribution di can be facilitated.

[0138] Figure 16 shows an example of defect distribution diagram Id4 displayed on the display unit 72 shown in Figure 13. The defect distribution diagram Id4 shown in Figure 16 visually displays the distribution di of defects in the b-axis direction (depth direction) from the front 101. If such a defect distribution diagram Id4 can be displayed on the display unit 72 of a head-mounted display, the distribution di of defects can be made known to workers, for example, at the inspection site.

[0139] In each of the above embodiments, the laser ultrasound inspection apparatus 1 is miniaturized, lightweight, and power-efficient. Therefore, the laser ultrasound inspection apparatus 1 can be easily incorporated into devices that are worn on the human body and operated by an internal power supply, such as the display device 71.

[0140] In the fourth embodiment described above, the same effects as in the first embodiment can be obtained. The display device of the present invention is not limited to the above, and may be, for example, a liquid crystal display device, an organic EL display device, an image projection device, etc.

[0141] 6. Fifth Embodiment Next, as a fifth embodiment, an electronic device equipped with a laser ultrasonic inspection device will be described. Figure 17 is a schematic diagram showing the general configuration of the electronic device 81 according to the fifth embodiment. Figure 18 is a schematic diagram showing the general configuration of the electronic device 83 according to the fifth embodiment.

[0142] The fifth embodiment will now be described, focusing on the differences from the first embodiment, and similar matters will be omitted from the description. In Figures 17 and 18, components similar to those in the first embodiment are denoted by the same reference numerals.

[0143] The electronic device 81 shown in Figure 17 is a smartphone and comprises a laser ultrasound inspection device 1 and a display unit 82. Examples of the display unit 82 include liquid crystal display devices and organic EL display devices. The display unit 82 displays the aforementioned defect distribution diagrams Id1, Id2, etc. In addition, it may display images acquired by the imaging unit 20 or object recognition results by the object recognition unit 62, etc., as needed.

[0144] An operator holding the electronic device 81 can perform an inspection of the subject 10 by scanning the electronic device 81 relative to the subject 10.

[0145] In the electronic device 81 shown in Figure 17, the first ejection window 524, the second ejection window 526, and the imaging window 528 are exposed on the surface. The imaging unit 20 mentioned above may be used for purposes other than the examination of the subject 10 in application software run on a smartphone.

[0146] With such an electronic device 81, since the laser ultrasound examination device 1 is incorporated into a smartphone used in daily life, it becomes easier to perform examinations on the subject 10.

[0147] The electronic device 83 shown in Figure 18 is an industrial robot comprising a robot arm 84 and a head unit 5 of a laser ultrasonic inspection device 1 attached to the tip of the robot arm 84. The robot arm 84 can change its posture, for example, according to a program. This allows the head unit 5 to be automatically positioned at the desired location in any posture. As a result, scanning of the head unit 5 can be performed automatically, and the inspection of the subject 10 can be performed automatically.

[0148] In the fifth embodiment described above, the same effects as in the first embodiment can be obtained. The electronic device of the present invention is not limited to the above, and may include, for example, a tablet terminal, a wearable device, etc. Since the laser ultrasound inspection device 1 is small, it can be mounted on an electronic device while keeping the overall size down.

[0149] 7. Sixth Embodiment Next, as a sixth embodiment, a mobile body equipped with a laser ultrasound inspection device will be described. Figure 19 is a schematic diagram showing the general configuration of the mobile body 85 according to the sixth embodiment. Figure 20 is a schematic diagram showing the general configuration of the mobile body 87 according to the sixth embodiment. Figure 21 is a schematic diagram showing the general configuration of the mobile body 89 according to the sixth embodiment.

[0150] The following describes the sixth embodiment, focusing on the differences from the first embodiment, and omitting explanations of similar matters. In Figures 19 and 20, components similar to those in the first embodiment are denoted by the same reference numerals.

[0151] The mobile unit 85 shown in Figure 19 is a roadbed inspection vehicle and comprises a vehicle body 86, which is an automobile, and a laser ultrasonic inspection device 1. The laser ultrasonic inspection device 1 is mounted on the vehicle body 86 so as to emit a first laser beam L11 and a second laser beam L12 toward the roadbed RD and to image the roadbed RD.

[0152] As the mobile unit 85 travels along the roadbed RD, the first laser beam L11 is scanned, allowing for efficient inspection of the roadbed RD, which is the object of inspection. Note that the object of inspection is not limited to the roadbed RD; it may also be, for example, tunnel walls, sound barriers, retaining walls, bridge girders, bridge piers, or other structures.

[0153] The mobile unit 87 shown in Figure 20 is a railway inspection vehicle and comprises a railway vehicle body 88 and a laser ultrasonic inspection device 1. The laser ultrasonic inspection device 1 is mounted on the vehicle body 88 to emit a first laser beam L11 and a second laser beam L12 toward the track RL and to image the track RL.

[0154] As the mobile unit 87 travels along the railway track RL, the first laser beam L11 is scanned, allowing for efficient inspection of the railway track RL, which is the object of inspection. Note that the object of inspection is not limited to the railway track RL; it may also be, for example, tunnel walls, sound barriers, retaining walls, bridge girders, bridge piers, or other structures.

[0155] The mobile device 89 shown in Figure 21 is a drone, comprising an airframe 80 and a head unit 5 of the laser ultrasonic inspection device 1. As mentioned above, the laser ultrasonic inspection device 1 has been made smaller, lighter, and more energy-efficient, so even when the head unit 5 is attached to the airframe 80, the impact on flight performance can be minimized.

[0156] As the mobile unit 89 flies along a structure or other object (not shown), the first laser beam L11 is scanned, allowing for efficient inspection of the structure or other object being inspected. The object to be inspected is not particularly limited, but may include high places, dangerous areas, high-radiation areas, etc., that are difficult for people to approach.

[0157] In the sixth embodiment described above, the same effects as in the first embodiment can be obtained. The mobile body of the present invention is not limited to the above, and may be, for example, a bicycle, motorcycle, ship, self-propelled robot, etc.

[0158] 8. Effects of the above embodiment As described above, the laser ultrasound inspection apparatus 1 according to the embodiment comprises a first laser light source 112, a vibration detection unit 13 (laser interferometer), an imaging unit 20, and a housing 52. The first laser light source 112 irradiates the subject 10 with pulsed first laser light L11. The vibration detection unit 13 detects the vibration VB of the subject 10, which originates from the ultrasound US induced in the subject 10 by the irradiation of the first laser light L11, using a second laser light L12. The imaging unit 20 captures the irradiation position of the first laser light L11 and the subject 10. The housing 52 houses the first laser light source 112, the vibration detection unit 13, and the imaging unit 20.

[0159] The vibration detection unit 13 also includes a second laser light source 134, a transducer-type optical modulator 132, and a photodiode 136 (light-receiving element). The second laser light source 134 irradiates the subject 10 with the second laser light L12. The transducer-type optical modulator 132 modulates the frequency of the second laser light L12 using the vibration element 130. The photodiode 136 receives the interference light between the second laser light L12 that has passed through the subject 10 and the second laser light L12 that has passed through the transducer-type optical modulator 132, and outputs a received signal S2.

[0160] Furthermore, the vibrating element 130 is a signal source for the reference signal Ss. The first laser light source 112 emits the first laser beam L11 based on the reference signal Ss. The imaging unit 20 performs imaging based on the reference signal Ss.

[0161] This configuration makes it possible to realize a laser ultrasonic inspection device 1 with a small number of parts, easy miniaturization, and excellent portability. Such a laser ultrasonic inspection device 1 can be easily held by an operator or attached to electronic equipment or mobile objects.

[0162] In the laser ultrasonic inspection apparatus 1 according to this embodiment, the imaging unit 20 may start exposure based on a reference signal Ss. Alternatively, the first laser light source 112 may emit the first laser light L11 after a predetermined time has elapsed since the imaging unit 20 started exposure based on the reference signal Ss.

[0163] With this configuration, even if there is a time lag between the rising edge of the laser detection signal S1 and the stabilization of the image sensor's operation, the irradiation position of the first laser beam L11 can be reliably captured in the image acquired by the image sensor.

[0164] In the laser ultrasound inspection apparatus 1 according to this embodiment, it is preferable that the optical axis of the first laser beam L11 irradiated onto the subject 10 and the optical axis of the second laser beam L12 irradiated onto the subject 10 are parallel to each other.

[0165] With this configuration, even when the head unit 5 is moved relative to the specimen 10, the distance between the irradiation position of the first laser beam L11 and the irradiation position of the second laser beam L12 can be kept constant. As a result, for example, when calculating the position of a defect def from the elapsed time Δt, it is no longer necessary to make corrections due to changes in the distance between the irradiation positions, thus reducing the amount of computation.

[0166] In the laser ultrasonic inspection apparatus 1 according to this embodiment, the housing 52 may have a first emission window 524 and a second emission window 526. In this case, the first emission window 524 emits a first laser beam L11 to the outside. The second emission window 526 emits a second laser beam L12 to the outside. The first emission window 524 and the second emission window 526 are spaced apart from each other.

[0167] With this configuration, it is possible to suppress the return of the second laser beam L12 reflected by the subject 10 to the first laser light source 112, and the incident of the first laser beam L11 reflected by the subject 10 onto the photodiode 136.

[0168] In the laser ultrasonic inspection apparatus 1 according to this embodiment, the vibration detection unit 13 (laser interferometer) has a signal processing unit 15 that detects vibration VB based on the received light signal S2. The signal processing unit 15 then detects vibration VB by demodulating the surface vibration signal from the received light signal S2 based on a reference signal Ss.

[0169] With this configuration, when demodulating the surface vibration signal from the received signal S2, the reference signal Ss can be used, which contributes to reducing the number of parts in the laser ultrasonic inspection device 1.

[0170] In the laser ultrasonic inspection apparatus 1 according to this embodiment, the signal processing unit 15 may measure the elapsed time Δt from the emission of the first laser beam L11 until the detection of vibration VB, based on the reference signal Ss.

[0171] With this configuration, when measuring the elapsed time Δt, the reference signal Ss can be used as a time reference, which contributes to reducing the number of parts in the laser ultrasonic inspection device 1.

[0172] In the laser ultrasound inspection apparatus 1 according to this embodiment, a defect detection unit 64 may be provided for detecting defects def contained in the subject 10. In this case, the defect detection unit 64 acquires a plurality of images from the imaging unit 20 in which the irradiation positions of the first laser beam L11 on the subject 10 are different from each other, calculates the irradiation position on the subject 10 based on the plurality of images, and detects defects def contained in the subject 10 based on the irradiation position and elapsed time Δt.

[0173] With this configuration, a laser ultrasound inspection device 1 can be realized that can detect defects def by calculating the elapsed time Δt from multiple images simply by scanning the irradiation position of the first laser beam L11 on the subject 10.

[0174] In the laser ultrasonic inspection apparatus 1 according to this embodiment, a thickness measuring unit 68 may be provided for measuring the thickness t10 of the specimen 10 based on the measurement result of the elapsed time Δt.

[0175] With this configuration, a laser ultrasound inspection device 1 capable of measuring the thickness t10 can be realized simply by scanning the irradiation position of the first laser beam L11 on the subject 10.

[0176] In the laser ultrasound inspection apparatus 1 according to this embodiment, the signal processing unit 15 may calculate the frequency of the detected vibration VB based on the reference signal Ss.

[0177] With this configuration, when calculating the frequency of vibration VB, the reference signal Ss can be used as a time reference, which contributes to reducing the number of parts in the laser ultrasonic inspection device 1.

[0178] In the laser ultrasound inspection apparatus 1 according to this embodiment, a defect detection unit 64 may be provided to detect defects def contained in the subject 10. In this case, the defect detection unit 64 acquires a plurality of images from the imaging unit 20 in which the irradiation positions of the first laser beam L11 on the subject 10 are different from each other, calculates the irradiation position on the subject 10 based on the plurality of images, and detects defects def contained in the subject 10 based on the irradiation position and the frequency of vibration VB.

[0179] With this configuration, a laser ultrasound inspection device 1 can be realized that can detect defects def by calculating the frequency of vibration VB from multiple images simply by scanning the irradiation position of the first laser beam L11 on the subject 10.

[0180] In the laser ultrasonic inspection apparatus 1 according to this embodiment, the defect detection unit 64 may generate defect distribution diagrams Id1 and Id2 representing the distribution di of defects contained in the sample 10.

[0181] With this configuration, a laser ultrasonic inspection device 1 is obtained that visually indicates the presence, location, and depth of defects def.

[0182] In the laser ultrasound inspection apparatus 1 according to this embodiment, an object recognition unit 62 may be provided to recognize the subject 10 by detecting the subject 10 in the image. In this case, the defect detection unit 64 calculates the irradiation position of the first laser beam L11 on the subject 10 based on the recognition result of the object recognition unit 62.

[0183] With this configuration, the coordinates of the subject 10's position within the image can be obtained. Furthermore, even if the relative size and position of the subject 10 with respect to the imaging unit 20 are not constant, the position of the subject 10 in the image can be determined, thereby improving the convenience of the examination.

[0184] In the laser ultrasound examination apparatus 1 according to this embodiment, a storage unit 66 for storing images acquired from the imaging unit 20 may be included.

[0185] With this configuration, the irradiation positions of the first laser beam L11 and the second laser beam L12 on the test subject 10 can be calculated while suppressing a temporary increase in the computational load in the defect detection unit 64.

[0186] The display device 71 according to the embodiment comprises a laser ultrasonic inspection apparatus 1 according to the embodiment, and a display unit 72 that displays defect distribution diagrams Id1 and Id2 (distribution diagrams of defects def detected by the laser ultrasonic inspection apparatus 1).

[0187] With this configuration, a display device 71 capable of supporting an intuitive understanding of the defect distribution di can be realized.

[0188] The electronic devices 81 and 83 according to this embodiment include the laser ultrasonic inspection apparatus 1 according to this embodiment.

[0189] With this configuration, for example, an electronic device 81 can be realized in which the head unit 5 is grasped by an operator and scanned relative to the object 10 to perform an inspection of the object 10, or an electronic device 83 can be realized in which the head unit 5 is operated by a robot arm 84 to perform an automatic inspection of the object 10.

[0190] The movable bodies 85, 87, and 89 according to this embodiment include the laser ultrasonic inspection apparatus 1 according to this embodiment.

[0191] With this configuration, the first laser beam L11 can be scanned by moving, and mobile units 85, 87, and 89 can be realized that can efficiently perform examinations of the subject.

[0192] Although the laser ultrasonic inspection apparatus, display device, electronic device, and mobile body of the present invention have been described above based on the illustrated embodiments, the present invention is not limited thereto.

[0193] For example, the laser ultrasonic inspection apparatus, display device, electronic device, and mobile body of the present invention may be configured such that each part of the above embodiment is replaced with any component having a similar function, or any component may be added to the above embodiment. Furthermore, the laser ultrasonic inspection apparatus of the present invention may have a configuration that combines two or more of the above embodiments. [Explanation of Symbols]

[0194] 1…Laser ultrasound inspection device, 5…Head unit, 6…Inspection control unit, 9…Laser ultrasound inspection device, 10…Subject, 11…Pulsed laser irradiation unit, 13…Vibration detection unit, 15…Signal processing unit, 20…Imaging unit, 22…Imaging unit, 31…Dichroic mirror, 32…Dichroic mirror, 40…Housing, 52…Housing, 62…Object recognition unit, 64…Defect detection unit, 66…Storage unit, 68…Thickness measurement unit, 71…Display device, 72…Display unit, 73… 80…Mounting unit, 81…Electronic equipment, 82…Display unit, 83…Electronic equipment, 84…Robot arm, 85…Mobile unit, 86…Vehicle body, 87…Mobile unit, 88…Vehicle body, 89…Mobile unit, 90…Subject, 91…Pulse laser irradiation unit, 93…Vibration detection unit, 95…Signal processing unit, 101…Front view, 112…First laser light source, 114…Amplifier, 116…Voltage-current converter, 118…Frequency converter, 130…Vibration element, 132…Oscillator-type optical modulator ,134...Second laser light source, 136...Photodiode, 142...First circuit, 144...Second circuit, 522...Main unit, 524...First emission window, 526...Second emission window, 528...Imaging window, 912...Laser light source, 914...Amplifier, 916...Voltage-current converter, 918...Signal generator, 922...Photodiode, 932...Acoustic-optic modulator, 934...Laser light source, 936...Photodiode, 938...Signal generator, CI...Composite image, D...Distance, DL...Reference line, E...Exposure time, F1...Beam image, F2...Beam image, F3...Beam image, FL...Frame line, Id1...Defect distribution map, Id2...Defect distribution map, Id3...Defect distribution map, Id4...Defect distribution map, L11...First laser beam, L111...First laser beam, L112...First laser beam, L12...Second laser beam, L91...Laser beam, L92...Laser beam, N...Number system, NE...Non-exposure time, Pi...Irradiation position information, P(X,Y)...Irradiation position, R...Reset signal, RD...Roadbed, RL...Train line, S1...Laser detection signal, S11...Pulse, S12...Pulse, S2...Received light signal, SX...Shift width, SZ...Distance, Sa...Drive signal, Sd...Pulse control signal, Ss...Reference signal, St...Imaging control signal, St1...Imaging control signal, St2...Imaging control signal, St3...Imaging control signal, TR...Scanning trajectory, US...Ultrasound, US1...Ultrasound, US2...Ultrasound, VB...Vibration, d...Displacement, d1...Displacement, d2...Displacement, def...Defect, di...Distribution, e1...Ellipse, e2...Ellipse, fo...Frequency analysis result, t10...Thickness, Δt...Elapsed time, Δt1...Elapsed time, Δt2...Elapsed time, δ...Shift angle

Claims

1. A first laser light source that irradiates the subject with pulsed first laser light, A laser interferometer that detects vibrations of the subject caused by ultrasound induced in the subject by irradiation with the first laser beam using a second laser beam, The imaging unit performs imaging of the irradiation position of the first laser beam and the subject, A housing that houses the first laser light source, the laser interferometer, and the imaging unit, Equipped with, The aforementioned laser interferometer is A second laser light source that irradiates the subject with the second laser light, A vibrator-type optical modulator that modulates the frequency of the second laser light using a vibrating element, A photodetector receives interference light between the second laser light that has passed through the subject and the second laser light that has passed through the oscillator-type optical modulator, and outputs a received signal. It has, The aforementioned vibrating element is a signal source for a reference signal, The first laser light source emits the first laser light based on the reference signal, The imaging unit is characterized by performing imaging based on the reference signal.

2. The imaging unit starts exposure based on the reference signal, The laser ultrasonic inspection apparatus according to claim 1, wherein the first laser light source emits the first laser light after a predetermined time has elapsed since the imaging unit started exposure, based on the reference signal.

3. The laser ultrasound inspection apparatus according to claim 1 or 2, wherein the optical axis of the first laser beam irradiated onto the subject and the optical axis of the second laser beam irradiated onto the subject are parallel to each other.

4. The aforementioned housing, A first emission window for emitting the first laser beam to the outside, A second emission window for emitting the second laser beam to the outside, It has, The laser ultrasonic inspection apparatus according to claim 3, wherein the first ejection window and the second ejection window are spaced apart from each other.

5. The laser interferometer has a signal processing unit that detects the vibration based on the received light signal, The laser ultrasonic inspection apparatus according to claim 1, wherein the signal processing unit detects the vibration by demodulating the surface vibration signal from the light-receiving signal based on the reference signal.

6. The laser ultrasonic inspection apparatus according to claim 5, wherein the signal processing unit measures the elapsed time from the emission of the first laser light to the detection of the vibration based on the reference signal.

7. The system includes a defect detection unit that detects defects contained in the subject, The defect detection unit is Multiple images of the subject, each with a different irradiation position, are acquired from the imaging unit. Based on the aforementioned multiple images, the irradiation position on the subject is calculated. The laser ultrasound inspection apparatus according to claim 6, which detects the defect contained in the subject based on the irradiation position and the elapsed time.

8. The laser ultrasonic inspection apparatus according to claim 6, further comprising a thickness measuring unit for measuring the thickness of the subject based on the measurement result of the elapsed time.

9. The laser ultrasonic inspection apparatus according to claim 5, wherein the signal processing unit calculates the frequency of the detected vibration based on the reference signal.

10. The system includes a defect detection unit that detects defects contained in the subject, The defect detection unit is Multiple images of the subject, each with a different irradiation position, are acquired from the imaging unit. Based on the aforementioned multiple images, the irradiation position on the subject is calculated. The laser ultrasound inspection apparatus according to claim 9, which detects the defect contained in the subject based on the irradiation position and the frequency of the vibration.

11. The laser ultrasonic inspection apparatus according to claim 7 or 10, wherein the defect detection unit generates a defect distribution diagram representing the distribution of defects contained in the subject.

12. The system includes an object recognition unit that recognizes the subject by detecting the subject in the aforementioned image, The laser ultrasonic inspection apparatus according to claim 7 or 10, wherein the defect detection unit calculates the irradiation position on the subject based on the recognition result of the subject by the object recognition unit.

13. The laser ultrasound inspection apparatus according to claim 1, further comprising a storage unit for storing images acquired from the imaging unit.

14. A laser ultrasound inspection apparatus according to claim 1, A display unit that displays a distribution map of defects detected by the laser ultrasonic inspection device, A display device characterized by having the following features.

15. An electronic device characterized by comprising the laser ultrasonic inspection apparatus described in claim 1.

16. A mobile body characterized by comprising the laser ultrasonic inspection apparatus described in claim 1.

Images