Measuring device, measuring system, mobile device, and measuring method

Abstract

To provide a measurement device, a measurement system, a mobile body, and a measurement method that can improve measurement accuracy when an irradiated sample is measured based on vibration generated by irradiating the sample with a laser beam.SOLUTION: A measurement device for measuring an inspection object based on vibration generated when the inspection object is irradiated with a laser beam includes: a laser device that radiates the laser beam; a condensing position deriving section that derives an adjustment amount of a distance between condensing lenses of a laser condensing unit for condensing the laser beam based on a distance from an irradiation point of the laser light; and a communication section that transmits control information including information indicating the adjustment amount to the laser condensing unit.SELECTED DRAWING: Figure 4

Description

Technical Field

[0004]

[0001] Embodiments of the present invention relate to a measuring device, a measuring system, a moving body, and a measuring method. This application claims priority based on Japanese Patent Application No. 2018-060867 filed in Japan on March 27, 2018, the content of which is incorporated herein by reference.

Background Art

[0002] Maintenance and inspection work of infrastructure such as tunnels is carried out by visual inspection and manual work (palpation, sound tapping, knocking off) of engineers. Therefore, the maintenance and inspection work takes a very long time and involves great danger. Thus, there is a need to automate and improve the efficiency of maintenance and inspection work of infrastructure such as tunnels. Regarding a technique for inspecting internal defects of concrete structures such as tunnel inner walls, a diagnostic method using laser-induced vibration waves has been proposed (for example, see Patent Document 1).

[0003] In the diagnostic method using laser-induced vibration waves, laser ablation is the most basic method of applying vibration to a sample, and the irradiated sample is diagnosed based on the vibration that occurs when the sample is irradiated with laser light. Laser ablation is an injection and evaporation phenomenon due to rapid heating and plasma formation of the sample caused by high-power laser pulse irradiation. The vibration generated in the sample is measured by an apparatus using laser measurement techniques such as a laser Doppler vibrometer and a laser interferometer. The vibration generated in the sample measured by an apparatus using laser measurement techniques is represented by an amplitude waveform with respect to time. The amplitude waveform with respect to time is converted into a vibration frequency spectrum by Fourier transform. Based on the change in the vibration frequency spectrum, since the vibration at the defect location becomes large, it is possible to inspect the state of the inspection target, such as whether internal defects such as cavities are present.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] When using laser-induced vibration waves for measurements outdoors, high-speed and high-precision measurements are difficult to achieve due to the strong influence of the measurement environment. For example, ambient noise (surrounding noise, reverberation) can introduce noise into the vibration spectrum, and unevenness of the irradiation area or the presence or absence of attached objects can make proper laser irradiation difficult. The present invention has been made to solve the above problems, and aims to provide a measuring device, measuring system, mobile body, and measuring method that can improve the measurement accuracy when measuring a sample based on vibrations generated when a sample is irradiated with laser light. [Means for solving the problem]

[0006] (1) One aspect of the present invention is a measuring device for measuring an object to be inspected based on vibrations generated when a laser beam is irradiated onto the object to be inspected, comprising: a laser device for irradiating the laser beam; a focusing position derivation unit for deriving an adjustment amount for the focusing position of a laser focusing unit for focusing the laser beam based on the distance between the laser device for irradiating the laser beam and the irradiation point of the laser beam; and a communication unit for transmitting control information including information indicating the adjustment amount to the laser focusing unit. (2) In one aspect of the present invention, the measuring device described in (1) above further comprises an irradiation location analysis unit that selects the location to be irradiated with the laser light based on information representing an image of the location to be irradiated with the laser light on the object to be inspected, and the communication unit transmits control information including information indicating the location to be irradiated with the laser light selected by the irradiation location analysis unit to a sweeping device that sweeps the laser light. (3) One aspect of the present invention is a measuring device as described in (1) or (2) above, further comprising: a reverberation data acquisition unit that acquires time-series data of reverberation sound generated when the laser light is irradiated onto the object to be inspected; and a reverberation analysis unit that acquires the timing for irradiating the object to be inspected with the laser light based on the intensity of the reverberation sound in the time-series data of reverberation sound acquired by the reverberation data acquisition unit, wherein the communication unit transmits control information including information indicating the timing acquired by the reverberation analysis unit to the laser device that irradiates the laser light. (4) One aspect of the present invention is a measuring device according to any one of the above items (1) to (3), further comprising a data removal unit that removes data from the measurement data of vibrations occurring in the object to be inspected, between the time the laser light was irradiated onto the object to be inspected and a predetermined time. (5) One aspect of the present invention is a measuring device according to any one of the above items (1) to (4), further comprising a noise reduction unit that removes noise from the measurement data based on a correlation coefficient between the measurement data of vibrations occurring in the object to be inspected and an evaluation function of the measurement data. (6) One aspect of the present invention is a measuring device according to any one of the above items (1) to (5), further comprising a noise reduction unit that removes noise from the measured data of vibration based on the measured data of vibration occurring in the object to be inspected and data obtained by shifting the phase of the time-series data of the measured data. (7) One aspect of the present invention is a measuring device according to any one of the above items (1) to (6), further comprising a determination unit that determines the soundness of the part of the inspection object irradiated with the laser light based on measurement data obtained when the inspection object is irradiated with the laser light to induce vibration in the inspection object and measurement data obtained when the inspection object is not irradiated with the laser light that induces vibration. (8) In one aspect of the present invention, in the measuring device described in any one of the above items (1) to (7), at least the laser focusing unit is housed in a soundproof enclosure. (9) One aspect of the present invention is a measurement system for measuring an object to be inspected based on vibrations generated when a laser beam is irradiated onto the object to be inspected, comprising: an excitation laser device that irradiates an object to be inspected with excitation laser light, which is laser light that causes vibrations; an excitation laser light focusing unit that focuses the excitation laser light irradiated by the excitation laser device; a focusing position derivation unit that derives a first adjustment amount for the focusing position of the excitation laser light focusing unit based on the distance between the excitation laser device and the irradiation point of the excitation laser light irradiated by the excitation laser device; and a communication unit that transmits control information including information indicating the first adjustment amount to the excitation laser light focusing unit, the measurement system comprising: an excitation laser device that irradiates an object to be inspected with excitation laser light, which is laser light that causes vibrations; an excitation laser light focusing unit that focuses the excitation laser light irradiated by the excitation laser device; and a measurement device that (10) One aspect of the present invention is a measurement system as described in (9) above, comprising a measurement laser device that irradiates the object to be inspected with measurement laser light, which is laser light for detecting vibrations induced in the object to be inspected, and a measurement laser focusing unit that focuses the measurement laser light irradiated by the measurement laser device, wherein the focusing position derivation unit derives a second adjustment amount for the focusing position of the measurement laser focusing unit based on the distance between the measurement laser device and the irradiation point of the measurement laser light irradiated by the measurement laser device, and the communication unit transmits control information including information indicating the second adjustment amount to the measurement laser focusing unit. (11) One aspect of the present invention is a measurement system described in (10) above, comprising a sweeping unit that sweeps the excitation laser light output by the excitation laser device and the measurement laser light output by the measurement laser device. (12) In one aspect of the present invention, in the measurement system described in any one of the above items (9) to (11), at least the vibration-generating laser light focusing unit is housed in a soundproof enclosure. (13) One aspect of the present invention is a mobile body equipped with the measurement system described in any one of the above items (9) to (11). (14) One aspect of the present invention is a measurement method performed by a measuring device for measuring an object to be inspected based on vibrations generated when the object to be inspected is irradiated with laser light, comprising the steps of: deriving an adjustment amount for the focusing position of a laser focusing unit that focuses the laser light based on the distance between a laser device that irradiates the laser light and the irradiation point of the laser light; and transmitting control information including information indicating the adjustment amount to the laser focusing unit. (15) One aspect of the present invention is a measurement method described in (14) above, further comprising the steps of selecting a location to be irradiated with laser light based on information representing an image of the location to be irradiated with laser light on the object to be inspected, and transmitting control information including information indicating the location to be irradiated with laser light to a sweeping device that sweeps the laser light. (16) One aspect of the present invention is a measurement method described in (14) or (15) above, further comprising the steps of: acquiring time-series data of reverberation sound generated when a laser beam is irradiated onto an object to be inspected at a certain timing; acquiring the timing for irradiating the object to be inspected with the laser beam based on the intensity of the reverberation sound in the time-series data of reverberation sound; and transmitting control information including information indicating the timing to a laser device that irradiates the laser beam. (17) One aspect of the present invention is a measurement method according to any one of the above paragraphs (14) to (16), further comprising the step of removing data from the measurement data of vibrations occurring in the object to be inspected between the time the laser light was irradiated onto the object to be inspected and a predetermined time. (18) One aspect of the present invention is a measurement method according to any one of (14) to (17) above, further comprising the step of removing noise from the measurement data based on a correlation coefficient between the measurement data of vibrations occurring in the object under inspection and an evaluation function of the measurement data. (19) One aspect of the present invention is a measurement method according to any one of the above items (14) to (18), further comprising the step of removing noise from the measurement data of vibration based on measurement data of vibration occurring in the object to be inspected and data obtained by shifting the phase of the time series data of the measurement data. (20) One aspect of the present invention is a measurement method according to any one of the above paragraphs (14) to (19), further comprising the step of determining the soundness of the part of the inspection object irradiated with the laser light based on measurement data obtained when the inspection object is irradiated with the laser light to induce vibration in the inspection object and measurement data obtained when the inspection object is not irradiated with the laser light that induces vibration. [Effects of the Invention]

[0007] According to embodiments of the present invention, when measuring an object to be inspected based on vibrations generated when the object is irradiated with laser light, the measurement accuracy can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of a laser-induced vibration wave measurement system according to the first embodiment. [Figure 2] This is a conceptual diagram of the sweep operation of the laser-induced vibration wave measurement system according to the first embodiment. [Figure 3A] This figure shows an example of the frequency spectrum of induced vibrations obtained by the processing unit of the laser-induced vibration wave measurement system of the first embodiment. [Figure 3B] This figure shows an example of the frequency spectrum of induced vibrations obtained by the processing unit of the laser-induced vibration wave measurement system of the first embodiment. [Figure 4] This is a block diagram showing an example of a processing unit for a laser-induced vibration wave measurement system according to the first embodiment. [Figure 5] This figure shows an example of an image of the area to be laser-irradiated. [Figure 6] This figure shows an example of sound information (part 1). [Figure 7A] Figure showing an example of sound information (part 2). [Figure 7B] Figure showing an example of sound information (part 2). [Figure 8A] Figure showing an example of sound information (part 3). [Figure 8B] Figure showing an example of sound information (part 3). [Figure 9A] Figure showing the noise reduction effect of the laser-induced vibration wave measurement system of the first embodiment. [Figure 9B] Figure showing the noise reduction effect of the laser-induced vibration wave measurement system of the first embodiment. [Figure 10] Figure showing an example of noise reduction of the laser-induced vibration wave measurement system of the first embodiment. [Figure 11] Figure showing an example of vibration data acquired by the laser-induced vibration wave measurement system of the first embodiment. [Figure 12] Figure showing the effect of removing suddenly-occurring noise by the laser-induced vibration wave measurement system of the first embodiment. [Figure 13A] Figure showing an example of the frequency spectrum determined by the laser-induced vibration wave measurement system of the first embodiment. [Figure 13B] Figure showing an example of the frequency spectrum determined by the laser-induced vibration wave measurement system of the first embodiment. [[ID=3z]] [Figure 14] Sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment (part 1). [Figure 15] Sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment (part 2). [Figure 16] Sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment (part 3). [Figure 17] Flowchart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment (part 4). [Figure 18]This is a block diagram showing an example of a processing unit for a laser-induced vibration wave measurement system according to a second embodiment. [Figure 19] This figure shows an example of noise reduction for the laser-induced vibration wave measurement system of the first embodiment. [Figure 20] This figure shows Example 1 of a laser-induced vibration wave measurement system, which is a modified example of the first embodiment. [Figure 21] This figure shows Example 2 of a laser-induced vibration wave measurement system, which is a modified example of the first embodiment. [Figure 22] This figure shows Example 3 of a laser-induced vibration wave measurement system, which is a modified example 1 of the first embodiment. [Figure 23A] This figure shows a side view of the laser optical port LP of a laser-induced vibration wave measurement system in a modified example 1 of the first embodiment. [Figure 23B] This figure shows a front view of the laser optical port LP of a laser-induced vibration wave measurement system according to Modification 1 of the first embodiment. [Figure 24] This diagram illustrates the minimum installation angle for the laser window LW. [Figure 25] This diagram illustrates the maximum angle of installation for the laser window LW. [Figure 26] This figure shows an example of a laser-induced vibration wave measurement system, which is a modified example 2 of the first embodiment. [Figure 27A] This figure shows an example of a laser-induced vibration wave measurement system, which is a modified example 3 of the first embodiment. [Figure 27B] This is a partially enlarged view of a laser-induced vibration wave measurement system according to a modified example 3 of the first embodiment. [Figure 28A] This figure shows example 1 of the effect of a sound barrier on a laser-induced vibration wave measurement system, modified example 3 of the first embodiment. [Figure 28B] This figure shows example 2 of the effect of a sound barrier on a laser-induced vibration wave measurement system, which is a modified example 3 of the first embodiment. [Figure 29] This figure shows example 3 of the effect of a sound barrier on a laser-induced vibration wave measurement system, which is a modified example 3 of the first embodiment. [Figure 30] This is a sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment. [Figure 31] This is a sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment. [Modes for carrying out the invention]

[0009] Next, the measuring device, measuring system, mobile body, and measuring method of this embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below. In all the figures used to illustrate the embodiments, components with the same function are given the same reference numerals, and repeated explanations are omitted. Furthermore, in this application, "based on XX" means "based on at least XX," and includes cases where it is based on another element in addition to XX. Also, "based on XX" is not limited to cases where XX is used directly, but also includes cases where it is based on something that has been calculated or processed from XX. "XX" is any element (for example, any information).

[0010] According to this embodiment, the measuring device performs high-speed measurements outdoors (where the environment is not constant) while eliminating in real time factors that reduce measurement accuracy, such as "changes in the distance between the laser irradiation area and the measurement target," "changes in the surface of the measurement target," and "sudden noise," which can cause measurement errors. The measuring device can measure the inspection target M by utilizing the fact that the vibration induced by the excitation laser changes depending on the state of the laser irradiation area. Here, the inspection target is a sample prepared according to standards for various performance tests such as strength and durability. It is possible to measure structures that are difficult to grasp from the appearance of the inspection target M (internal cavities, direction of crack propagation). For example, it is suitable for measuring infrastructure structures mainly made of concrete. Furthermore, because rapid measurement is possible, it is suitable for detailed measurements and wide-area measurements for structures such as tunnels and bridges.

[0011] (First embodiment) (Laser-induced vibration wave measurement system) Figure 1 shows an example of a laser-induced vibration wave measurement system according to the first embodiment. In Figure 1, solid lines represent optical paths and dashed lines represent signal lines. The laser-induced vibration wave measurement system 20 measures the object M being inspected based on the vibrations generated when the object M is irradiated with laser light. The laser-induced vibration wave measurement system 20 comprises an excitation laser device 1, a measurement laser device 2, a galvanometer scanner unit 3, a two-axis mirror unit 5, a reverberation sound monitor 7, mirrors 8a, 8b, and 8c, a distance measuring laser device 9, an excitation laser focusing unit 10, a measurement laser focusing unit 11, an imaging device 13, and a processing unit 100.

[0012] The vibration-generating laser device 1 outputs a high-power laser pulse, which is then irradiated onto the object to be inspected M. This causes vibration to be generated (induced) in the object to be inspected M. An example of the vibration-generating laser device 1 is a high-power pulsed laser, such as a Q-switched Nd:YAG laser. The measuring laser device 2 detects vibrations induced in the object under inspection M. The measuring laser device 2 generates laser light (hereinafter referred to as "measuring laser light") for detecting vibrations induced in the object under inspection M, and outputs the generated measuring laser light. The measuring laser device 2 acquires the laser light reflected or scattered by the object under inspection M, and converts the acquired laser light into vibration quantities such as displacement and displacement velocity. The measuring laser device 2 outputs information indicating the vibration quantities obtained by converting the laser light to the processing unit 100. An example of the measuring laser device 2 is a laser interferometer or a laser Doppler vibrometer. Here, if a laser interferometer acquires information as displacement, or if a laser Doppler vibrometer acquires information as velocity, this information is converted into vibration quantities. Although a measuring device using a laser is explained as an example, it is not limited to this as long as it can detect vibrations induced in the object under inspection M.

[0013] The distance measuring laser device 9 measures the distance between the distance measuring laser device 9 and the inspection target M (hereinafter referred to as "irradiation distance"), and outputs information indicating the irradiation distance obtained by the measurement to the processing unit 100. Such distance measuring laser device 9 can be any conventionally known device without any particular restrictions. In the following description, a distance measuring device using laser light will be used as an example, but it is not limited to this as long as it is capable of measuring the irradiation distance. The galvanometer scanner unit 3 and the dual-axis mirror unit 5 sweep the laser light output by the excitation laser device 1 (hereinafter referred to as "excitation laser light"), the measurement laser light output by the measurement laser device 2, and the laser light output by the distance measuring laser device 9 (hereinafter referred to as "distance measuring laser light"). While the combination of the galvanometer scanner unit 3 and the dual-axis mirror unit 5 is described as an example of a mechanism for sweeping the excitation laser light, measurement laser light, and distance measuring laser light, such a laser light sweeping mechanism is not limited to the combination of the galvanometer scanner unit 3 and the dual-axis mirror unit 5, as long as it can sweep at least one of these laser lights.

[0014] The reverberation monitor 7 acquires time-series data of the sound (hereinafter referred to as "reverberation") in which the explosive sound generated by the ablation of the surface of the object under inspection M penetrates the interior of the reverberation monitor 7 and is superimposed as noise on the signal waveform. Specifically, the reverberation monitor 7 measures the intensity of the sound produced when either or both of the excitation laser light and the measurement laser light are irradiated onto the object under inspection M, and outputs the sound information obtained by measuring the sound intensity to the processing unit 100. The reverberation monitor 7 is realized by converting sound measured using a so-called acoustic measuring device such as a microphone into an electrical signal. Alternatively, the vibration of the measuring device (typically a part of the measuring device) caused by the reverberation may be measured with an acceleration sensor to obtain sound information of the reverberation. Note that the reverberation measured by the reverberation monitor 7 is not limited to sounds in the audible frequency range (e.g., 20Hz to 20kHz), but also includes so-called ultrasound with a frequency of 20kHz or higher. The reverberation should be measured at frequencies that affect the measurement of vibrations of the inspection target M induced by the excitation laser. The installation location of the reverberation monitor 7 is not particularly limited as long as it is possible to measure reverberation. Figure 1 shows it attached to the two-axis mirror unit 5. In this embodiment, we will continue the explanation in the case where the reverberation monitor 7 acquires sound generated when the excitation laser beam is irradiated onto the inspection target M. By attaching the reverberation monitor 7 to the two-axis mirror unit 5, sound can be measured at the closest position to where the excitation laser beam is irradiated onto the inspection target M. Mirror 8a bends the optical path of the excitation laser beam output by the excitation laser device 1 at a right angle. Mirror 8b bends the optical path of the distance measuring laser beam output by the distance measuring laser device 9 at a right angle.

[0015] The vibration laser focusing unit 10 focuses the vibration laser light output by the vibration laser device 1. The vibration laser focusing unit 10 includes lenses 12a and 12b for focusing the vibration laser light. Mirror 8c bends the optical path of the vibration laser beam focused by the vibration laser focusing unit 10 at a right angle. The measurement laser focusing unit 11 focuses the measurement laser light output by the measurement laser device 2. The measurement laser focusing unit 11 includes lenses 12c and 12d for focusing the measurement laser light.

[0016] The imaging device 13 is attached to the two-axis mirror unit 5 and images the area of ​​the inspection target M that is to be illuminated with laser light. The imaging device 13 outputs information representing the image of the area of ​​the inspection target M that is to be illuminated with laser light, obtained by imaging, to the processing unit 100. Because the imaging device 13 is attached to the two-axis mirror unit 5, images of the area to be illuminated with laser light can be acquired in accordance with the movement of the two-axis mirror unit 5.

[0017] The optical path of the excitation laser device 1 is bent at a right angle by mirror 8a and introduced into the excitation laser focusing unit 10. In other words, the excitation laser light output by the excitation laser device 1 is bent at a right angle by mirror 8a and proceeds to the excitation laser focusing unit 10. The excitation laser focusing unit 10 outputs excitation laser light so as to focus it onto the surface of the object to be inspected M. The excitation laser light output by the excitation laser focusing unit 10 is bent at a right angle by mirror 8c and proceeds to the galvanometer scanner unit 3.

[0018] The optical path of the measurement laser device 2 is introduced into the measurement laser focusing unit 11. In other words, the measurement laser light output by the measurement laser device 2 travels to the measurement laser focusing unit 11. The measurement laser focusing unit 11 focuses the measurement laser light and outputs the focused measurement laser light to the galvanometer scanner unit 3.

[0019] The galvanometer scanner unit 3 adjusts the optical paths of either the excitation laser beam or the measurement laser beam, or both, to any direction and angle by rotating the galvanometer scanner mirrors 4a and 4b to appropriate angles using motors. The excitation laser beam and the measurement laser beam, whose optical paths have been adjusted to the desired direction and angle by the galvanometer scanner unit 3, are output to the two-axis mirror unit 5. The dual-axis mirror unit 5 adjusts the dual-axis mirror 6 to set a coarse irradiation position, which is difficult for the galvanometer scanner unit 3. The excitation laser light and measurement laser light output to the dual-axis mirror unit 5 are irradiated onto the planned irradiation position of the inspection target M set by the dual-axis mirror unit 5.

[0020] Figure 2 is a conceptual diagram of the sweep of the laser-induced vibration wave measurement system according to the first embodiment. When the dual-axis mirror unit 5 irradiates the inspection target M with both the excitation laser beam and the measurement laser beam, it sweeps in the following order according to the preset sweep sequence SO-1: dual-axis mirror irradiation area 203-1, dual-axis mirror irradiation area 203-2, dual-axis mirror irradiation area 203-3, and dual-axis mirror irradiation area 203-4. When the dual-axis mirror unit 5 sweeps the dual-axis mirror irradiation area 203-1, the galvanometer scanner unit 3 sweeps in the order of irradiation area 200-11, irradiation area 200-12, irradiation area 200-13, irradiation area 200-14, and irradiation area 200-15 according to the preset sweep sequence SO-11. When the galvanometer scanner unit 3 sweeps the irradiation area 200-11, the galvanometer scanner mirror 4a and the galvanometer scanner mirror 4b are rotated to an appropriate angle by a motor, so that the excitation laser beam and the measurement laser beam are irradiated onto the excitation laser beam irradiation area and the measurement laser beam irradiation area, respectively. When the galvanometer scanner unit 3 sweeps illumination areas 200-12 to 200-15, the processing used when sweeping illumination area 200-11 can be applied. Similarly, when the dual-axis mirror unit 5 sweeps dual-axis mirror illumination areas 203-2 to 203-4, the processing used when sweeping dual-axis mirror illumination area 203-1 can be applied. In this way, by combining the galvanometer scanner unit 3 and the dual-axis mirror unit 5, the laser beam can be rapidly swept to any point on the inspection target M. For example, in the case of a tunnel with a radius of 5m to 10m, the spacing of the dots 200 within the measurement range of a 0.1m to 1m square area 203 is preferably 10mm to 300mm. Let's return to Figure 1 and continue the explanation.

[0021] The laser-induced vibration wave measurement system 20 adjusts the focusing position of the excitation laser focusing unit 10. Specifically, the laser-induced vibration wave measurement system 20 adjusts the focusing position by adjusting the distance between lens 12a and lens 12b mounted on the excitation laser focusing unit 10. The laser-induced vibration wave measurement system 20 also adjusts the distance between lens 12c and lens 12d mounted on the measurement laser focusing unit 11. Furthermore, the laser-induced vibration wave measurement system 20 sets the location where the excitation laser light and the measurement laser light are irradiated onto the object M to be inspected. Furthermore, the laser-induced vibration wave measurement system 20 reduces the effects of sound generated when either or both of the excitation laser light and the measurement laser light are irradiated onto the object M being inspected, as sound is produced, and also reduces the effects of sound reflection.

[0022] This section describes the process of adjusting the distance between lenses 12a and 12b mounted on the vibration laser focusing unit 10, and the distance between lenses 12c and 12d mounted on the measurement laser focusing unit 11. By adjusting the distance between lenses 12a and 12b mounted on the vibration laser focusing unit 10, and the distance between lenses 12c and 12d mounted on the measurement laser focusing unit 11, the "change in distance between the laser irradiation unit and the measurement target" can be compensated for by adjusting the laser focusing position, thereby improving the measurement accuracy when performing high-speed measurements. The distance-measuring laser beam output by the distance-measuring laser device 9 is bent at a right angle by mirror 8b and proceeds to the galvanometer scanner unit 3. The galvanometer scanner unit 3 includes a galvanometer scanner mirror 4a and a galvanometer scanner mirror 4b. The galvanometer scanner unit 3 adjusts the optical path of the distance-measuring laser beam to any direction and angle by rotating the galvanometer scanner mirrors 4a and 4b to appropriate angles using motors. The distance-measuring laser beam, whose optical path has been adjusted to the desired direction and angle by the galvanometer scanner unit 3, is output to the two-axis mirror unit 5.

[0023] The dual-axis mirror unit 5 is equipped with a dual-axis mirror 6, and by adjusting the dual-axis mirror 6, it is possible to set a coarse irradiation position, which is difficult with the galvanometer scanner unit 3. The distance measuring laser beam output to the dual-axis mirror unit 5 is irradiated onto the irradiation position of the inspection target M set by the dual-axis mirror unit 5. The reflected light of the distance measuring laser beam irradiated onto the irradiation position of the inspection target M travels through the two-axis mirror unit 5, the galvanometer scanner unit 3, and the mirror 8b to the distance measuring laser device 9, where it is detected by the light-receiving element of the distance measuring laser device 9. Based on the reflected light detected by the light-receiving element, the distance measuring laser device 9 derives the irradiation distance between the distance measuring laser device 9 and the inspection target M, and outputs information indicating the derived irradiation distance (irradiation distance information) to the processing unit 100.

[0024] The processing unit 100 acquires information indicating the irradiation distance output by the distance measuring laser device 9, and derives the amount of adjustment for the distance between lens 12a and lens 12b of the excitation laser focusing unit 10 and the time required for that adjustment based on the acquired information indicating the irradiation distance. The processing unit 100 adjusts the distance between lens 12a and lens 12b based on the derived adjustment amount. Specifically, the processing unit 100 outputs information indicating the derived adjustment amount for the distance between lens 12a and lens 12b to the excitation laser focusing unit 10. The excitation laser focusing unit 10 acquires the information indicating the adjustment amount for the distance between lens 12a and lens 12b output by the processing unit 100, and adjusts the distance between lens 12a and lens 12b based on the acquired information indicating the adjustment amount for the distance between lens 12a and lens 12b. The adjustment of the distance between lens 12a and lens 12b is performed by moving either one or both of lens 12a and lens 12b. By adjusting the distance between lens 12a and lens 12b, the excitation laser beam can be focused and irradiated onto the inspection target M.

[0025] Figures 3A and 3B show examples of frequency spectra of induced vibrations obtained by the processing unit of the laser-induced vibration wave measurement system of the first embodiment. In Figures 3A and 3B, the horizontal axis represents the frequency of the induced vibration, and the vertical axis represents the normalized vibration intensity. The normalized vibration intensity is set to 1 when the peak value before adjustment is set. Figure 3A shows the frequency spectrum obtained when the distance between lens 12a and lens 12b is not adjusted. Figure 3B shows the frequency spectrum obtained when the distance between lens 12a and lens 12b is adjusted. For example, in Figures 3A and 3B, the focusing diameter of the excitation laser beam when the distance between lens 12a and lens 12b is not adjusted (Figure 3A) is 7.9 mm, and the focusing diameter of the excitation laser beam when the distance between lens 12a and lens 12b is adjusted (Figure 3B) is 4.4 mm. As shown in Figure 3A, if the distance between lens 12a and lens 12b is not adjusted, the focusing diameter of the excitation laser beam widens, which reduces the irradiation intensity per unit area of ​​the excitation laser beam that excites the surface vibration of the object M being inspected. As a result, the signal intensity in the frequency spectrum decreases. The frequency spectra of the induced vibrations shown in Figures 3A and 3B were obtained by excitation using the ablation mode. Furthermore, by widening the focal diameter, the signal intensity decreases, but it is possible to switch to a thermal mode that measures without damaging the surface by ablation, relying solely on thermal expansion. In thermal mode, the focal diameter of the excitation laser beam is approximately 100 mm. Therefore, a focal diameter of 100 μm to 100 mm is preferable for the excitation laser beam. As shown in Figure 3B, when the distance between lenses 12a and 12b is adjusted, the focusing diameter of the excitation laser beam narrows, increasing the irradiation intensity per unit area of ​​the excitation laser beam that excites the surface vibrations of the object M being inspected. Therefore, the signal intensity in the frequency spectrum improves. A suitable irradiation intensity per unit area is between 10 mJ / cm² and 10 kJ / cm². Returning to Figure 1, we continue the explanation.

[0026] The processing unit 100 acquires information indicating the irradiation distance output by the distance measuring laser device 9, and derives the amount of adjustment for the distance between lens 12c and lens 12d of the measuring laser focusing unit 11 and the time required for that adjustment based on the acquired information indicating the irradiation distance. Based on the derived adjustment amount, the processing unit 100 adjusts the distance between lens 12c and lens 12d. Specifically, the processing unit 100 outputs information indicating the derived adjustment amount for the distance between lens 12c and lens 12d to the excitation laser focusing unit 10. The excitation laser focusing unit 10 acquires the information indicating the adjustment amount for the distance between lens 12c and lens 12d output by the processing unit 100, and adjusts the distance between lens 12c and lens 12d based on the acquired information indicating the adjustment amount for the distance between lens 12c and lens 12d. The adjustment of the distance between lens 12c and lens 12d is performed by moving either one or both of lens 12c and lens 12d. By adjusting the distance between lens 12c and lens 12d, the measurement laser beam can be focused and directed onto the inspection target M. If the distance between lens 12c and lens 12d is not adjusted, the measurement laser system that detects vibrations in the focusing position will be unable to perform measurements because the focusing position will not be set on the object being inspected.

[0027] Next, we will explain the process of setting the location on the inspection target M to be irradiated with at least one of the excitation laser beam, measurement laser beam, and distance measuring laser beam. By setting the location on the inspection target M to be irradiated with at least one of the excitation laser beam, measurement laser beam, and distance measuring laser beam, "changes in the surface of the measurement target" can be eliminated, thus eliminating one of the causes of measurement errors when performing high-speed measurements. The imaging device 13 images the areas of the inspection target M that are to be irradiated with laser light. The imaging device 13 transmits to the processing unit 100 information representing the image of the area of ​​the inspection target M that is to be irradiated with at least one of the excitation laser light, measurement laser light, and distance measurement laser light obtained by imaging (hereinafter referred to as the "laser irradiation area image"). Specifically, the imaging device 13 images the irradiation areas 200-11, ..., irradiation areas 200-15, ... as described with reference to Figure 2. The processing unit 100 acquires information representing the laser irradiation area image transmitted by the imaging device 13 and processes the acquired information representing the laser irradiation area image. Based on the laser irradiation area image obtained through image processing, the processing unit 100 detects the state of the inspection target M, such as wetness, shape, and attachments. Based on the state of the inspection target M, the processing unit 100 selects a laser irradiation area from among multiple laser irradiation areas to be irradiated with either the excitation laser beam or the measurement laser beam, or both.

[0028] For example, based on the condition of the object M to be inspected, it is preferable to select a laser irradiation area that is flat, free of unevenness and shadows, has the same level of wetness as other areas to be laser-irradiated, and has no attached objects. It is preferable to avoid areas with attached objects, cracks (including inside cracks), repaired areas, and marked areas as areas to be laser-irradiated. Based on the selected laser irradiation locations, the processing unit 100 selects the shortest route among the routes indicated by lines connecting all the selected laser irradiation locations. Alternatively, if there are routes that pass over attached objects, the processing unit 100 may select the shortest route by assuming that a physical shutter will block the laser beam from irradiating the objects. The processing unit 100 outputs the selected route as the sweep route, along with information indicating the swept route, to the galvanometer scanner unit 3 and the dual-axis mirror unit 5. The galvanometer scanner unit 3 and the dual-axis mirror unit 5 sweep at least one of the excitation laser beam, measurement laser beam, and distance measuring laser beam based on the result of selecting the irradiation area output by the processing unit 100.

[0029] This section describes a process to reduce the effects of sound generated when at least one of the excitation laser beam, measurement laser beam, or distance measuring laser beam is irradiated onto the inspection target M, as well as the effects of that sound's reverberation. The sound generated when irradiated onto the inspection target M, and the reverberation of that sound, together are called reverberation. By reducing the effects of sound generated when at least one of the excitation laser beam, measurement laser beam, or distance measuring laser beam is irradiated onto the inspection target M, as well as the effects of that sound's reverberation, "noise originating from the inspection environment" can be eliminated, thus eliminating one of the causes of measurement errors when performing high-speed measurements. When performing laser-induced vibration wave measurements in enclosed spaces such as tunnels, sound generated by either the excitation laser beam or the measurement laser beam, or both, irradiating the object being inspected M, may reverberate, and this reverberated sound may become noise. At the first timing, the inspection target M is irradiated with either the excitation laser beam or the measurement laser beam, or both. The reverberation monitor 7 measures the intensity of sound produced when either or both of the excitation laser beam and the measurement laser beam are irradiated onto the inspection target M at a first timing. Here, sound includes the sound produced when either or both of the excitation laser beam and the measurement laser beam are irradiated onto the inspection target M, the sound that reverberates off the tunnel walls, etc., and reverberation. The reverberation monitor 7 converts the measured sound into an electrical signal and outputs the sound intensity obtained by the conversion into an electrical signal (hereinafter referred to as "sound information") to the processing unit 100.

[0030] The processing unit 100 generates time-series data of reverberation intensity based on the sound information output by the reverberation monitor 7. The reverberation monitor 7 measures the intensity of sound produced when either or both of the excitation laser beam and the measurement laser beam are irradiated onto the object under inspection. The reverberation monitor 7 converts the measured sound into an electrical signal and outputs the resulting sound information to the processing unit 100. The processing unit 100 generates time-series data of reverberation intensity based on the sound information output by the reverberation monitor 7. The time-series data of reverberation will be explained using Figure 7A. S1 is the time-series data of reverberation measured when either or both of the excitation laser beam and the measurement laser beam are irradiated onto the inspection target at timing 0ms. For example, the signals observed at 20ms, 50ms, 75ms, etc. in S1 are reverberation. Since the time-series data of reverberation changes depending on the measurement environment (e.g., tunnel size, shape, distance to the inspection target, etc.), it is desirable to measure it each time the measurement environment changes and output it to the processing unit 100.

[0031] The processing unit 100 derives the laser irradiation timing that minimizes the influence of reverberation and maximizes the time period during which the vibration of the object being inspected M can be measured, based on the time-series data of reverberation. For example, in Figure 7A, a total of four laser irradiations and measurements are performed at 20ms intervals. Sx is the time-series data of the reverberation generated during the xth irradiation, and the measurement is performed during the time period Mx immediately after the laser irradiation. Since reverberation is generated for each irradiation, the reverberation from the first x-1 laser irradiations (S1 to S(x-1)) is added and remains in the measurement time period Mx. If the peak of the reverberation is included in the measurement time period, the measurement accuracy will decrease. For example, the measurement time period M3 includes the peaks of both S1 and S2. The processing unit 100 derives the laser irradiation timing that minimizes the influence of the reverberation from previous irradiations for each measurement. Specifically, as shown in Figure 7B, the laser irradiation timing (interval) is derived that minimizes the intensity of the time-series data obtained by adding S1 to S(x-1) during the measurement time period of Mx. Note that the time-series data of the reverberation sound generated by one laser irradiation is the same each time unless the measurement environment changes, so if the measurement environment does not change, the same time-series data can be used for S1 to Sx. The processing unit 100 outputs information indicating the derived timing to either the excitation laser device 1 or the measurement laser device 2, or both. Since it is undesirable to change the timing while the galvanometer scanner unit 3 is performing a high-speed sweep, it is preferable for the processing unit 100 to change the timing at the timing when the high-speed sweep range is changed by the two-axis mirror unit 5, that is, while the high-speed sweep unit is stopped. Either or both of the excitation laser device 1 and the measurement laser device 2 output either the excitation laser light or the measurement laser light, based on information indicating the timing output by the processing unit 100.

[0032] The processing unit 100, which constitutes the laser-induced vibration wave measurement system 20, will be described in detail. (Processing unit 100) Figure 4 is a block diagram showing an example of a processing unit for a laser-induced vibration wave measurement system according to the first embodiment. The processing unit 100 is implemented by a device such as a personal computer, server, smartphone, tablet computer, or industrial computer. The processing unit 100 includes, for example, a communication unit 110, an information processing unit 120, a display unit 130, and a storage unit 140. The communication unit 110 is implemented by a communication module. The communication unit 110 communicates with other external devices via a network. The communication unit 110 may communicate using communication methods such as wireless LAN (Local Area Network), wired LAN, Bluetooth (registered trademark), or LTE (Long Term Evolution) (registered trademark).

[0033] The communication unit 110 receives information indicating the irradiation distance output by the distance measuring laser device 9 and outputs the received information indicating the irradiation distance to the information processing unit 120. The communication unit 110 acquires control information, including information indicating the adjustment amount of the focusing position, such as the adjustment amount of the distance between lens 12a and lens 12b, output by the information processing unit 120, in response to the information indicating the irradiation distance, and outputs the acquired control information including the information indicating the adjustment amount of the focusing position to the vibration laser focusing unit 10. Furthermore, the communication unit 110 acquires control information, including information indicating the amount of adjustment for the focusing position, such as the amount of adjustment for the distance between lens 12c and lens 12d, output by the information processing unit 120, in response to the information indicating the irradiation distance, and outputs the acquired control information to the measurement laser focusing unit 11. The communication unit 110 receives information representing the laser irradiation area image output by the imaging device 13 and outputs the received information representing the laser irradiation area image to the information processing unit 120. The communication unit 110 acquires control information, including the result of selecting the irradiation area output by the information processing unit 120, based on the information representing the laser irradiation area image, and outputs the acquired control information to the galvanometer scanner unit 3 and the dual-axis mirror unit 5. The communication unit 110 outputs the sound information output by the reverberation monitor 7 to the information processing unit 120. The communication unit 110 acquires control information, including information indicating the timing output by the information processing unit 120, in relation to the sound information, and outputs the acquired control information to either the vibration laser device 1 or the measurement laser device 2, or both. The communication unit 110 outputs the vibration data output by the measuring laser device 2 to the information processing unit 120.

[0034] The display unit 130 is composed of, for example, a liquid crystal display and displays the inspection results of the soundness of the part of the inspection target M that has been irradiated with the excitation laser light. The storage unit 140 is implemented by, for example, RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), flash memory, or a hybrid storage device combining several of these. Instead of being provided as part of the processing unit 100, part or all of the storage unit 140 may be implemented by an external device accessible via a network by the processor of the processing unit 100, such as a NAS (Network Attached Storage) or an external storage server. The storage unit 140 stores a program 142 executed by the information processing unit 120, a lens distance table 144, and a peripheral measurement data DB (Database) 146. The lens distance table 144 is a table-formatted information that associates information indicating the irradiation distance, the focal position adjusted by the excitation laser focusing unit 10 to focus at that irradiation distance, the focal position adjusted by the measurement laser focusing unit 11, and the time required to adjust the focal position. In this embodiment, we will continue the explanation of the case in which the focal position is adjusted by the measurement laser focusing unit 11 by adjusting the lens distance between lens 12a and lens 12b, and the focal position of the measurement laser focusing unit 11 is adjusted by adjusting the lens distance between lens 12c and lens 12d. The surrounding measurement data DB146 stores vibration data measured in the past.

[0035] The information processing unit 120 is a functional unit (hereinafter referred to as the software functional unit) that is realized by a processor such as a CPU (Central Processing Unit) executing a program 142 stored in the memory unit 140. The information processing unit 120, in whole or in part, may be realized by hardware such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array), or by a combination of the software functional unit and hardware. The information processing unit 120 includes, for example, an information acquisition unit 122, a measurement unit 124, and an analysis unit 126. The information acquisition unit 122 includes an irradiation distance data acquisition unit 122a, an irradiation location data acquisition unit 122b, a reverberation sound data acquisition unit 122c, and a vibration data acquisition unit 122d. The irradiation distance data acquisition unit 122a acquires information indicating the irradiation distance output by the communication unit 110 and outputs the acquired information indicating the irradiation distance to the measurement unit 124. The irradiation location data acquisition unit 122b acquires information representing the laser irradiation location image output by the communication unit 110, and outputs the acquired information representing the laser irradiation location image to the measurement unit 124. The reverberation sound data acquisition unit 122c acquires the sound information output by the communication unit 110 and outputs the acquired sound information to the measurement unit 124. The vibration data acquisition unit 122d acquires the vibration data output by the communication unit 110 and outputs the acquired vibration data to the analysis unit 126.

[0036] (Measurement unit 124) The measurement unit 124 includes a light focusing position derivation unit 124a, an irradiation location analysis unit 124b, a reverberation sound analysis unit 124c, and a timing derivation unit 124d. The focusing position derivation unit 124a acquires information indicating the irradiation distance output by the irradiation distance data acquisition unit 122a, and derives the amount of adjustment for the distance between lens 12a and lens 12b, the amount of adjustment for the distance between lens 12c and lens 12d, and the time required to adjust the distance between the lenses based on the acquired information indicating the irradiation distance. Specifically, the focusing position derivation unit 124a acquires information indicating the current distance between lens 12a and lens 12b from the vibration laser focusing unit 10 and stores the acquired information indicating the current distance between lens 12a and lens 12b. It is preferable that the focusing position derivation unit 124a acquires information indicating the current distance between lens 12a and lens 12b during the high-speed sweep of the galvanometer scanner unit 3, in other words, at the timing when the galvanometer scanner unit 3 stops. Furthermore, the focusing position derivation unit 124a acquires information indicating the current distance between lens 12c and lens 12d from the measurement laser focusing unit 11 and stores the acquired information indicating the current distance between lens 12c and lens 12d. It is preferable that the focusing position derivation unit 124a acquires information indicating the current distance between lens 12c and lens 12d during the high-speed sweep of the galvanometer scanner unit 3, in other words, at the timing when the galvanometer scanner unit 3 stops.

[0037] When the focusing position deriving unit 124a acquires information indicating the irradiation distance, it refers to the inter-lens distance table 144 and acquires the inter-lens distance between lens 12a and lens 12b, which is stored in association with the acquired information indicating the irradiation distance, and the time required to adjust the inter-lens distance. The focusing position deriving unit 124a derives the amount of adjustment required for the distance between lens 12a and lens 12b by deriving the difference between the acquired inter-lens distance between lens 12a and lens 12b and the current distance between lens 12a and lens 12b. The focusing position deriving unit 124a outputs the information indicating the amount of adjustment required for the distance between lens 12a and lens 12b, and the time required to adjust the inter-lens distance, to the timing deriving unit 124d. Furthermore, when the focusing position derivation unit 124a acquires information indicating the irradiation distance, it refers to the inter-lens distance table 144 and acquires the inter-lens distance between lens 12c and lens 12d, which is stored in association with the acquired information indicating the irradiation distance, and the time required to adjust the inter-lens distance. The focusing position derivation unit 124a derives the amount of adjustment required for the distance between lens 12c and lens 12d by deriving the difference between the acquired inter-lens distance between lens 12c and lens 12d and the current distance between lens 12c and lens 12d. The focusing position derivation unit 124a outputs the information indicating the amount of adjustment required for the distance between lens 12c and lens 12d, and the time required to adjust the inter-lens distance, to the timing derivation unit 124d.

[0038] The irradiation area analysis unit 124b acquires information representing the laser irradiation area image output by the irradiation area data acquisition unit 122b, and processes the acquired information representing the laser irradiation area image. Based on the laser irradiation area image obtained through image processing, the irradiation area analysis unit 124b detects the state of the inspection target M, such as wetness, shape, and attachments. Based on the state of the inspection target M, the irradiation area analysis unit 124b selects a laser irradiation area that is flat, free of uneven shadows, has the same wetness as other laser irradiation areas, and has no attachments. The irradiation area analysis unit 124b, for example, based on the selected laser irradiation locations, selects the shortest route among the routes indicated by lines connecting all the selected laser irradiation locations. Furthermore, if there is a route that passes over an accessory, the irradiation area analysis unit 124b may select the shortest route by assuming that a physical shutter blocks the laser light so that it does not irradiate the accessory. The irradiation area analysis unit 124b uses the selected route as the sweep route and outputs the result of selecting irradiation locations, including information indicating the sweep route, to the timing derivation unit 124d. By using the shortest route among the routes connecting all the selected laser irradiation locations as the sweep route, the sweep can be performed at the fastest possible speed.

[0039] Figure 5 shows an example of an image of the laser irradiation area. The example image of the laser irradiation area shown in Figure 5 shows a total of 25 laser (vibration laser) irradiation areas arranged in a 5x5 grid. Furthermore, cable C is shown in the example image of the laser irradiation area. Based on the image of the laser irradiation locations, the irradiation location analysis unit 124b determines that laser irradiation is not possible for the laser irradiation locations indicated by (X,Y) (2,4), (3,3), and (4,3) out of the 25 laser irradiation locations because cable C is located above them. The irradiation location analysis unit 124b selects the laser irradiation locations other than those indicated by (X,Y) (2,4), (3,3), and (4,3), and selects the shortest route among the routes indicated by lines connecting all the selected laser irradiation locations. The irradiation location analysis unit 124b uses the selected route as the sweep route and outputs the result of selecting irradiation locations including information indicating the sweep route to the timing derivation unit 124d. Return to Figure 4 and continue the explanation.

[0040] The reverberation analysis unit 124c derives measurement conditions based on the sound information output by the reverberation data acquisition unit 122c. Figure 6 shows an example of sound information (part 1). In Figure 6, the horizontal axis represents time [ms], and the vertical axis represents sound intensity (arb.unit). This sound information was obtained at an inspection speed of 50 Hz, meaning 50 measurements were taken per second. In the example shown in Figure 6, the inspection target M is irradiated with an excitation laser beam every 20 ms. Therefore, every 20 ms, sound is generated when the excitation laser beam is irradiated onto the inspection target M, and multiple peaks L due to this sound are detected. Furthermore, 8 ms after each of the multiple peaks L, a peak N and decay waveform due to the reverberation of the sound generated when the excitation laser beam is irradiated onto the inspection target M are detected for several milliseconds. Since each of the multiple peaks N and decay waveforms is noise, if the time during which each of the multiple peaks N is detected is included in the measurement time, the measurement accuracy will deteriorate. This will be explained in detail.

[0041] Figures 7A and 7B show an example of sound information (part 2). Figures 8A and 8B show an example of sound information (part 3). Figure 7A shows the reverberation sound generated when the inspection target M is sequentially irradiated with vibration laser light at 20ms intervals (50Hz). Because the measurement environment in Figure 7A is different from that in Figure 6, the timing of noise generation due to reverberation is different. Also, the waveform of the reverberation appears as a single peak in Figure 6, while it appears as a decayed waveform in Figure 7A; this is due to the difference in irradiation energy. Afterimage sound is a periodic sound signal that arrives outside of the irradiation time of the vibration laser light. Figure 7B shows the reverberation sound produced by each sequentially irradiated excitation laser beam when the inspection target M is irradiated with excitation laser beams at 30ms intervals (33Hz). In Figures 7A and 7B, S1-S4 are waveforms showing the reverberation sound generated when the inspection target M is sequentially irradiated with excitation laser light. M1-M4 are the time periods during which the vibrations generated in the inspection target M are measured in response to the sequentially irradiated laser light. The upward arrows indicate the timing of irradiation with the excitation laser light.

[0042] Figure 8A shows the reverberation sound produced by each sequentially irradiated excitation laser beam when the inspection target M is irradiated with excitation laser beams at 25 ms intervals (40 Hz). Figure 8B shows the reverberation sound generated by each sequentially irradiated excitation laser beam when the inspection target M is irradiated with excitation laser beams at 40ms intervals (25Hz). In Figures 8A and 8B, S1-S4 are waveforms showing the reverberation sound generated when the inspection target M is sequentially irradiated with excitation laser light. M1-M4 are the time periods during which the vibrations generated in the inspection target M are measured in response to the sequentially irradiated laser light. The upward arrows indicate the timing of irradiation with the excitation laser light.

[0043] According to Figures 7A, 7B, 8A, and 8B, in the time period of the second and subsequent measurements (measurements) represented by M2-M4, the reverberation (noise) from the previous irradiation is included in the measurement results. In other words, the vibration measured in the time period Mn (where n is an integer n>1) includes the waveform obtained by adding all of waveforms S1-Sn. Specifically, in the case of Figure 7A, the vibration measured in the time period M4 includes waveforms S1-S4 in the measurement results. Of waveforms S1-S4, waveforms S2 and S3 have particularly large amplitudes and large noise components. However, in the case of Figure 7B, the vibration measured in the time period M4 includes waveforms S1-S4 in the measurement results, but of waveforms S1-S4, all of them have small amplitudes and small noise components. In Figure 8A, the vibrations measured during the M4 time period include waveforms S1-S4 in the measurement results. Of waveforms S1-S4, waveform S2 has a particularly large amplitude and a large noise component. In Figure 8B, the vibrations measured during the M4 time period include waveforms S1-S4 in the measurement results. Of waveforms S1-S4, waveform S3 has a particularly large amplitude and a large noise component.

[0044] The time waveform of reverberation differs depending on the irradiation environment, such as the size of the tunnel, the road (road surface), the bridge pier deck, the concrete wall, and the position of the reverberation monitor 7. Before measuring vibrations, the reverberation analysis unit 124c derives measurement conditions, such as the number of repetitions (timing) that minimizes noise components, based on the sound information acquired by the reverberation monitor 7. For example, as shown in Figure 6, the reverberation analysis unit 124c derives a timing that allows the noise level to become quieter to about twice or less the signal amount before irradiation (background), and that this quiet period to be approximately 10 ms. For example, if the laser-induced vibration wave measurement system 20 is mounted on a moving object, as described later, the timing is derived after the object is stationary. When the reverberation sounds shown in Figures 7A, 7B, 8A, and 8B are obtained, the reverberation analysis unit 124c derives a measurement condition of 30ms interval (33Hz) and outputs the derived measurement condition to the timing derivation unit 124d and the analysis unit 126. In this way, by optimizing the number of repetitions (timing), it is possible to perform measurements that reduce the influence of noise components generated by sequentially irradiated excitation laser light. Returning to Figure 4, the explanation continues.

[0045] The timing derivation unit 124d acquires information indicating the amount of adjustment of the distance between lens 12a and lens 12b output by the focusing position derivation unit 124a, and time information required for adjusting the distance between lenses. Based on the acquired time information required for adjusting the distance between lenses, it outputs control information including the acquired information indicating the amount of adjustment of the distance between lens 12a and lens 12b to the communication unit 110 at a predetermined timing. The timing derivation unit 124d acquires information indicating the amount of adjustment of the distance between lens 12c and lens 12d output by the focusing position derivation unit 124a, and time information required for adjusting the distance between lenses. Based on the acquired time information required for adjusting the distance between lenses, it outputs control information including the acquired information indicating the amount of adjustment of the distance between lens 12c and lens 12d to the communication unit 110 at a predetermined timing. The timing derivation unit 124d acquires information indicating the result of selecting the irradiation area output by the irradiation area analysis unit 124b, and outputs control information including the acquired information indicating the result of selecting the irradiation area to the communication unit 110 at a predetermined timing. The timing derivation unit 124d acquires information indicating the measurement conditions output by the reverberation sound analysis unit 124c, and outputs control information including the acquired measurement conditions to the communication unit 110 at a predetermined timing.

[0046] (Analysis Department 126) The analysis unit 126 comprises a data processing unit 126a and a determination unit 126b. The data processing unit 126a acquires the measurement conditions output by the timing derivation unit 124d and the vibration data output by the vibration data acquisition unit 122d, and processes the acquired vibration data based on the acquired measurement conditions. The data processing unit 126a removes data for a certain period of time and then acquires data for a set measurement period. Specifically, for example, if the measurement period is set to 10ms, the data processing unit 126a removes the 10ms data and then acquires the irradiation data for 10ms-20ms. Here, the vibration data may be obtained by irradiating the same location on the object M being inspected with a single pulse of the excitation laser beam, or by irradiating it with multiple pulses. However, when using data obtained by irradiating with multiple pulses of the excitation laser beam, the data processing unit 126a may average or integrate the vibration data output by the vibration data acquisition unit 122d.

[0047] The data processing unit 126a extracts data for measurement time periods M1, M2, ... from the vibration data based on the measurement conditions output by the timing derivation unit 124d. The data processing unit 126a also removes a reduction amount, arbitrarily determined from the maximum displacement amount of vibration generated by the excitation laser, from the extracted data for time periods M1, M2, .... Here, an example of a reduction amount is 1 / 10, 1 / 100, etc., and this is data for a predetermined time, such as 0.5ms-10ms, after irradiation with the excitation laser light. By removing the reduction amount, arbitrarily determined from the maximum displacement amount of vibration generated by the excitation laser light, after irradiation with the excitation laser light, the influence of noise that occurs immediately after irradiation with the excitation laser light can be reduced, thereby improving measurement accuracy. Figures 9A and 9B show the effect of noise reduction on the laser-induced vibration wave measurement system of the first embodiment. Figures 9A and 9B show the frequency spectrum obtained by performing a Fast Fourier Transform on the vibration data. Figure 9A shows the vibration data without noise reduction, while Figure 9B shows the vibration data with noise reduction. As shown in Figure 9A, the noise caused by the sound generated by the irradiation of the vibrating laser light has a significant impact, resulting in a generally raised white noise. In contrast, as shown in Figure 9B, the white noise is reduced, and finer peaks are visible.

[0048] Furthermore, the data processing unit 126a determines whether the acquired vibration data contains noise caused by sudden measurement errors. In laser-induced vibration wave measurement, the vibration generated in the object M under inspection is strongest immediately after irradiation with the excitation laser light, and then decreases exponentially over time. The data processing unit 126a uses this exponential function as an evaluation function and algorithmically determines that vibration data that does not show a correlation coefficient of a certain level or higher with this trend contains noise caused by sudden measurement errors. Figure 10 shows an example of noise reduction for the laser-induced vibration wave measurement system of the first embodiment. In Figure 10, (a) is a normal signal (attenuated waveform), and (b) is noise caused by a sudden measurement error. The data processing unit 126a uses the attenuated waveform shown in (a) as an evaluation function to derive a correlation coefficient between it and the waveform shown in (b). If the correlation coefficient is greater than or equal to the correlation coefficient threshold, the data processing unit 126a determines that the waveform shown in (b) is a signal. If the correlation coefficient is less than the correlation coefficient threshold, the data processing unit 126a determines that the waveform shown in (b) is not a signal but noise caused by a sudden measurement error. The data processing unit 126a determines that the data containing noise caused by a sudden measurement error is invalid data and removes the invalid data. Returning to Figure 4, the explanation continues.

[0049] The data processing unit 126a obtains valid data by removing invalid data. Here, if the acquired valid data is data obtained by irradiating the same location of the inspection target M with multiple vibration laser beams, the data processing unit 126a removes the noise that was abruptly generated as a result of irradiating the same location with multiple vibration laser beams from the valid data. Specifically, since the number of times that noise abruptly generated as a result of irradiating the same location with multiple vibration laser beams is mixed into the vibration data is small compared to the total number of irradiations, the data processing unit 126a removes data containing noise that was abruptly generated as a result of irradiating the same location with multiple vibration laser beams by extracting a predetermined number of waveforms with high correlation coefficients with the waveforms obtained by averaging the vibration data over time. The data processing unit 126a may remove either noise caused by a sudden measurement error or noise that occurs suddenly, or it may remove both.

[0050] Figure 11 shows an example of vibration data acquired by the laser-induced vibration wave measurement system of the first embodiment. Figure 11 shows vibration data for 16 seconds when the same location on the object M being inspected is measured 160 times at an inspection speed of 10 Hz, with the horizontal axis representing time (seconds) and the vertical axis representing vibration intensity (arb.unit). If these 160 measurements are divided and the 160 data points are averaged and then subjected to a Fast Fourier Transform (FFT), a frequency spectrum similar to that in Figure 9B is obtained. As shown in Figure 11, in a series of band signals with vibration intensities ranging from -0.001 to 0.001, in addition to the periodic peaks that occur when the excitation laser beam is irradiated every 100 ms, a peak due to suddenly occurring noise can be seen. Specifically, N in Figure 11 indicates the location of the signal where sudden noise occurred. When sudden noise occurs, the black band shown as a standard bulges out. In Figure 11, the thin, equally spaced lines represent white noise.

[0051] Figure 12 shows the effect of removing suddenly occurring noise in the laser-induced vibration wave measurement system of the first embodiment. Figure 12 shows the frequency spectrum obtained by performing an FFT after removing the suddenly occurring noise. Compared to the frequency spectrum obtained by performing an FFT without removing the suddenly occurring noise (lower figure in Figure 9), a clearer frequency spectrum is obtained. The data processing unit 126a outputs information representing the frequency spectrum to the determination unit 126b. The data processing unit 126a stores the acquired vibration data, the data obtained in the noise removal process, and the information representing the frequency spectrum in the peripheral measurement data DB 146 of the storage unit 140. Return to Figure 4 and continue the explanation.

[0052] The determination unit 126b inspects the integrity of the portion of the object M that has been irradiated with the excitation laser light, based on the frequency spectrum output by the data processing unit 126a. Specifically, the determination unit 126b detects the presence or absence of internal defects such as cavities, or the possibility that such internal defects have occurred. Furthermore, the determination unit 126b uses the frequency spectrum obtained by irradiating the inspection target M with the vibrating laser light and the frequency spectrum stored in the peripheral measurement data DB 146 of the storage unit 140 to inspect the integrity of the part of the inspection target M irradiated with the vibrating laser light. Specifically, the determination unit 126b detects the presence or absence of internal defects such as cavities, or the possibility that such internal defects have occurred. The determination unit 126b may also apply machine learning to inspect the integrity of the part of the inspection target M irradiated with the vibrating laser light. When inspecting the integrity of the part of the inspection target M irradiated with the vibrating laser light, the determination unit 126b may also use the frequency spectrum obtained when the vibrating laser light is not irradiated.

[0053] Figures 13A and 13B show examples of frequency spectra determined by the laser-induced vibration wave measurement system 20 of the first embodiment. Figure 13A is the frequency spectrum obtained when the inspection target M is irradiated with excitation laser light. Figure 13B is the frequency spectrum obtained when the inspection target M is not irradiated with excitation laser light. In other words, Figure 13B is background data. According to Figure 13B, even when the inspection target M is not irradiated with excitation laser light, natural vibration peaks can be seen around 2.5 kHz and 5.5 kHz. According to Figure 13A, it can be seen that when the inspection target M is irradiated with excitation laser light, the natural vibration peaks are larger. The judgment unit 126b includes background data in the frequency spectrum stored in the peripheral measurement data DB 146 of the memory unit 140. The judgment unit 126b may automatically generate accurate judgment criteria by reflecting information that affects the judgment, such as natural vibrations, including background data. The determination unit 126b displays information on the display unit 130 indicating the results of the inspection of the soundness of the part of the inspection target M that was irradiated with the excitation laser light.

[0054] (Operation of the laser-induced vibration wave measurement system 20 (Part 1)) Figure 14 is a sequence chart showing an example (part 1) of the operation of the laser-induced vibration wave measurement system of the first embodiment. Figure 14 shows an example of adjusting the focusing position of the excitation laser focusing unit 10, specifically the process of adjusting the distance between lens 12a and lens 12b and the distance between lens 12c and lens 12d of the measurement laser focusing unit 11. (Step S101) The distance measuring laser device 9 outputs distance measuring laser light. (Step S102) The distance measuring laser device 9 derives the irradiation distance between the distance measuring laser beam and the inspection target M based on the reflected light from the inspection target M after the distance measuring laser beam is output. (Step S103) The distance measuring laser device 9 transmits information indicating the derived irradiation distance (irradiation distance information) to the processing unit 100. (Step S104) The communication unit 110 of the processing unit 100 receives irradiation distance information transmitted by the distance measuring laser device 9 and outputs the received irradiation distance information to the information acquisition unit 122. The irradiation distance data acquisition unit 122a of the information acquisition unit 122 acquires the irradiation distance information output by the communication unit 110 and outputs the acquired irradiation distance information to the measurement unit 124. The focusing position derivation unit 124a of the measurement unit 124 acquires the irradiation distance information output by the irradiation distance data acquisition unit 122a and obtains the inter-lens distance between lens 12a and lens 12b associated with the acquired irradiation distance information from the inter-lens distance table 144 stored in the storage unit 140.

[0055] (Step S105) The focusing position deriving unit 124a derives the amount of adjustment for the distance between lens 12a and lens 12b by deriving the difference between the acquired inter-lens distance between lens 12a and lens 12b and the current distance between lens 12a and lens 12b. The focusing position deriving unit 124a outputs information indicating the derived amount of adjustment for the distance between lens 12a and lens 12b to the timing deriving unit 124d. (Step S106) The timing derivation unit 124d acquires information indicating the amount of adjustment for the distance between lens 12a and lens 12b output by the focusing position derivation unit 124a, creates control information including the acquired information indicating the amount of adjustment for the distance between lens 12a and lens 12b, and outputs the created control information to the communication unit 110. The communication unit 110 transmits the control information output by the timing derivation unit 124d to the vibration laser focusing unit 10.

[0056] (Step S107) The vibration-activated laser focusing unit 10 receives control information transmitted by the processing unit 100. Based on the information in the received control information indicating the amount of adjustment for the distance between lens 12a and lens 12b, the vibration-activated laser focusing unit 10 adjusts the distance between lens 12a and lens 12b. (Step S108) The communication unit 110 of the processing unit 100 receives irradiation distance information transmitted by the distance measuring laser device 9 and outputs the received irradiation distance information to the information acquisition unit 122. The irradiation distance data acquisition unit 122a of the information acquisition unit 122 acquires the irradiation distance information output by the communication unit 110 and outputs the acquired irradiation distance information to the measurement unit 124. The focusing position derivation unit 124a of the measurement unit 124 acquires the irradiation distance information output by the irradiation distance data acquisition unit 122a and obtains the inter-lens distance between lens 12c and lens 12d associated with the acquired irradiation distance information from the inter-lens distance table 144 stored in the storage unit 140. (Step S109) The focusing position deriving unit 124a derives the amount of adjustment for the distance between lens 12c and lens 12d by deriving the difference between the acquired inter-lens distance between lens 12c and lens 12d and the current distance between lens 12c and lens 12d. The focusing position deriving unit 124a outputs information indicating the derived amount of adjustment for the distance between lens 12c and lens 12d to the timing deriving unit 124d.

[0057] (Step S110) The timing derivation unit 124d acquires information indicating the amount of adjustment for the distance between lens 12c and lens 12d output by the focusing position derivation unit 124a, creates control information including the acquired information indicating the amount of adjustment for the distance between lens 12c and lens 12d, and outputs the created control information to the communication unit 110. The communication unit 110 transmits the control information output by the timing derivation unit 124d to the measurement laser focusing unit 11. (Step S111) The measurement laser focusing unit 11 receives control information transmitted by the processing unit 100. Based on the information included in the received control information indicating the amount of adjustment for the distance between lens 12c and lens 12d, the measurement laser focusing unit 11 adjusts the distance between lens 12c and lens 12d. In the sequence chart shown in Figure 14, steps S104-S107 and steps S108-S111 may be swapped. Also, step S108 may be performed after step S104, or after step S105.

[0058] (Operation of the laser-induced vibration wave measurement system 20 (Part 2)) Figure 15 is a sequence chart showing an example (part 2) of the operation of the laser-induced vibration wave measurement system of the first embodiment. Figure 15 shows the process of controlling the irradiation area of ​​the inspection target M by the galvanometer scanner unit 3 and the biaxial mirror unit 5. (Step S201) The imaging device 13 images the area of ​​the object M to be inspected that is to be irradiated with laser light. (Step S202) The imaging device 13 transmits information representing the laser irradiation area image of the inspection target M obtained by imaging to the processing unit 100.

[0059] (Step S203) The communication unit 110 of the processing unit 100 receives information representing the laser irradiation area image of the inspection target M transmitted by the imaging device 13, and outputs the received information representing the laser irradiation area image of the inspection target M to the information acquisition unit 122. The irradiation area data acquisition unit 122b of the information acquisition unit 122 acquires the information representing the laser irradiation area image of the inspection target M output by the communication unit 110, and outputs the acquired information representing the laser irradiation area image of the inspection target M to the measurement unit 124. The irradiation area analysis unit 124b of the measurement unit 124 acquires the information representing the laser irradiation area image of the inspection target M output by the irradiation area data acquisition unit 122b, and processes the acquired information representing the laser irradiation area image of the inspection target M. (Step S204) The irradiation area analysis unit 124b of the processing unit 100 detects the state of the inspection target M, such as wetness, shape, and attachments, based on the laser irradiation area image obtained by image processing. (Step S205) The irradiation location analysis unit 124b of the processing unit 100 selects a laser irradiation location from among multiple planned laser irradiation locations to which at least one of the excitation laser beam, measurement laser beam, and distance measurement laser beam will be irradiated, based on the state of the object M to be inspected.

[0060] (Step S206) The irradiation location analysis unit 124b of the processing unit 100 selects the shortest route among the routes indicated by lines connecting all the selected laser irradiation locations, based on the selected laser irradiation locations. Furthermore, if there is a route that passes over an accessory, the irradiation location analysis unit 124b may select the shortest route by assuming that the laser light is blocked by a physical shutter to prevent it from irradiating the accessory. The processing unit 100 outputs the selected route as a sweep route, along with information indicating the sweep route, to the timing derivation unit 124d as the result of selecting the irradiation locations. (Step S207) The timing derivation unit 124d acquires the result of selecting the irradiation area output by the irradiation area analysis unit 124b, creates control information including the acquired result of selecting the irradiation area, and outputs the created control information to the communication unit 110. The communication unit 110 transmits the control information output by the timing derivation unit 124d to the galvanometer scanner unit 3 and the dual-axis mirror unit 5. (Step S208) The galvanometer scanner unit 3 acquires control information transmitted by the processing unit 100 and adjusts at least one optical path from among the excitation laser beam, measurement laser beam, and distance measuring laser beam based on the result of selecting the irradiation area included in the acquired control information. (Step S209) The dual-axis mirror unit 5 acquires control information transmitted by the processing unit 100 and adjusts at least one optical path from among the excitation laser beam, measurement laser beam, and distance measuring laser beam based on the result of selecting the irradiation area included in the acquired control information.

[0061] (Operation of the laser-induced vibration wave measurement system 20 (Part 3)) Figure 16 is a sequence chart showing an example (part 3) of the operation of the laser-induced vibration wave measurement system of the first embodiment. Figure 16 shows the process of controlling the output timing of the excitation laser beam. As an example, Figure 16 describes a case in which the timing of outputting the excitation laser beam is derived based on the intensity of the sound produced when the excitation laser beam is shone onto the object to be inspected M. (Step S301) The reverberation sound analysis unit 124c of the processing unit 100 creates excitation laser light irradiation information, which is information for irradiating the excitation laser device 1 with excitation laser light, and outputs the created excitation laser light irradiation information to the communication unit 110. The communication unit 110 acquires the excitation laser light irradiation information output by the reverberation sound analysis unit 124c and transmits the acquired excitation laser light irradiation information to the excitation laser device 1. The excitation laser light irradiation information includes information indicating the timing of the excitation laser light output. Specifically, the excitation laser light irradiation information includes the first timing, the second timing, ..., the i-th timing as the timing for outputting the excitation laser light. (Step S302) The vibration laser device 1 outputs vibration laser light according to the vibration laser light irradiation information transmitted by the processing unit 100. The vibration laser light output by the vibration laser device 1 is irradiated onto the object to be inspected M. (Step S303) The reverberation monitor 7 measures the sound produced when the exciting laser beam is shone onto the object M at the first timing, the second timing, ..., and the i-th timing. The reverberation monitor 7 converts the measured sound into an electrical signal and acquires the sound information converted into an electrical signal.

[0062] (Step S304) The reverberation monitor 7 transmits the acquired sound information to the processing unit 100. (Step S305) The communication unit 110 of the processing unit 100 receives sound information transmitted by the reverberation monitor 7 and outputs the received sound information to the information acquisition unit 122. The reverberation data acquisition unit 122c of the information acquisition unit 122 acquires the sound information output by the communication unit 110 and outputs the acquired sound information to the measurement unit 124. The reverberation analysis unit 124c of the measurement unit 124 acquires the sound information output by the reverberation data acquisition unit 122c and derives measurement conditions based on the acquired sound information. The reverberation analysis unit 124c outputs information indicating the derived measurement conditions to the timing derivation unit 124d. (Step S306) The timing derivation unit 124d acquires information indicating the measurement conditions output by the timing derivation unit 124d, creates control information including the acquired information indicating the measurement conditions, and outputs the created control information to the communication unit 110. The communication unit 110 transmits the control information output by the timing derivation unit 124d to the vibration laser device 1. (Step S307) The vibration laser device 1 acquires control information transmitted by the processing unit 100 and outputs vibration laser light according to the measurement conditions included in the acquired control information.

[0063] (Operation of the laser-induced vibration wave measurement system 20 (Part 4)) Figure 17 is a flowchart showing an example (part 4) of the operation of the laser-induced vibration wave measurement system of the first embodiment. Figure 17 shows the process of determining whether the area of ​​the object to be inspected M that was irradiated with the excitation laser light is sound or not by processing vibration data. (Step S401) The communication unit 110 of the processing unit 100 receives vibration data (vibration amount) transmitted by the measuring laser device 2 and outputs the received vibration data to the information acquisition unit 122. The vibration data acquisition unit 122d of the information acquisition unit 122 acquires the vibration data output by the communication unit 110. (Step S402) The vibration data acquisition unit 122d outputs the acquired vibration data to the analysis unit 126. The data processing unit 126a of the analysis unit 126 extracts data for the time period during which measurement is performed from the vibration data, based on the vibration data output by the vibration data acquisition unit 122d and the measurement conditions output by the timing derivation unit 124d. (Step S403) The data processing unit 126a removes noise caused by sudden measurement errors from the extracted time period data by removing a reduction amount arbitrarily determined from the maximum displacement amount of vibration generated by the excitation laser. Here, an example of the reduction amount is 1 / 10, 1 / 100, etc. (Step S404) The data processing unit 126a determines whether or not the acquired vibration data contains sudden noise. The data processing unit 126a determines that the data contains sudden noise to be invalid data and removes the invalid data. (Step S405) The determination unit 126b inspects the integrity of the portion of the object M that has been irradiated with the excitation laser light, based on the frequency spectrum output by the data processing unit 126a.

[0064] (Step S406) The display unit 130 displays the inspection results for the soundness of the portion of the inspection target M that has been irradiated with the excitation laser light. After the processing in step S406 is completed, the timing derivation unit 124d derives the timing based on information output by the focusing position derivation unit 124a indicating the amount of adjustment of the distance between lens 12a and lens 12b, information indicating the amount of adjustment of the distance between lens 12c and lens 12d, time information required for adjusting the distance between lenses, information output by the irradiation location analysis unit 124b indicating the result of selecting the irradiation location, and information output by the reverberation sound analysis unit 124c indicating the measurement conditions. Based on the derived timing, the unit proceeds to the process of irradiating the next excitation laser beam. The timing derivation unit 124d transmits the derived timing information from the communication unit 110 to the excitation laser device 1, galvanometer scanner unit 3, biaxial mirror unit 5, excitation laser focusing unit 10, and measurement laser focusing unit 11. The laser irradiation adjustment unit of the vibration laser device 1 acquires timing information transmitted by the processing unit 100 and corrects the timing of outputting the vibration laser light by adjusting the master clock, physical shutter, etc., based on the acquired timing information. The drive adjustment units of the galvanometer scanner unit 3, the two-axis mirror unit 5, the vibration laser focusing unit 10, and the measurement laser focusing unit 11 each acquire timing information transmitted by the processing unit 100 and drive at an appropriate speed and at an appropriate time based on the acquired timing information. In the flowchart shown in Figure 17, steps S403 and S404 may be swapped.

[0065] In the embodiment described above, the case in which the reverberation monitor 7 measures the sound produced when the excitation laser light is irradiated onto the object M being inspected was explained, but the invention is not limited to this example. For example, the reverberation monitor 7 may be configured to measure the sound produced when the measurement laser light is irradiated onto the object M being inspected. In the embodiment described above, the case in which the reverberation monitor 7 is attached to the biaxial mirror unit 5 was explained, but the invention is not limited to this example. For example, the reverberation monitor 7 may be attached to the galvanometer scanner unit 3, or to the vibration laser device 1 or the measurement laser device 2. In the embodiments described above, an example of a reverberation monitor 7 was described in which a so-called acoustic measurement device such as a microphone is used, but the invention is not limited to this example. For example, as a reverberation monitor 7, an acceleration sensor may be installed in a laser-induced vibration wave measurement system, and sound may be measured by measuring the vibration of the housing and optical elements caused by reverberation. In the embodiments described above, we have described a case where mirror 8a bends the optical path of the excitation laser beam at a right angle, mirror 8b bends the optical path of the distance measuring laser beam at a right angle, and mirror 8c bends the optical path of the excitation laser beam at a right angle, but the invention is not limited to this example. For example, the optical system may be designed so that mirror 8a bends the optical path of the excitation laser beam at an arbitrary angle by designing an optical element such as 30 degrees or 60 degrees. Similarly, the optical system may be designed so that mirror 8b bends the optical path of the distance measuring laser beam at an arbitrary angle by designing an optical element such as 30 degrees or 60 degrees. Furthermore, the optical system may be designed so that mirror 8c bends the optical path of the excitation laser beam at an arbitrary angle by designing an optical element such as 30 degrees or 60 degrees. In the embodiment described above, the case in which the vibration-induced laser focusing unit 10 includes lens 12a and lens 12b was explained, but it is not limited to this example. For example, the vibration-induced laser focusing unit 10 may include a single lens or a combination of three or more lenses. The focusing position and degree of focusing may be adjusted by adjusting the installation position of the single lens or the combination of three or more lenses. The lenses may be convex lenses or concave lenses. In the embodiments described above, the case in which the measuring laser focusing unit 11 includes lens 12c and lens 12d was explained, but it is not limited to this example. For example, the measuring laser focusing unit 11 may include a single lens or a combination of three or more lenses. The focusing position and focusing degree may be adjusted by adjusting the installation position of the single lens or the combination of three or more lenses. The lenses may be convex lenses or concave lenses. In the embodiment described above, the case in which the galvanometer scanner unit 3 includes two mirrors, a galvanometer scanner mirror 4a and a galvanometer scanner mirror 4b, was explained, but the invention is not limited to this example. For example, the galvanometer scanner unit 3 may include one galvanometer scanner mirror, or it may include three or more galvanometer scanner mirrors. In the embodiments described above, the case in which the dual-axis mirror unit 5 includes a dual-axis mirror was explained, but the invention is not limited to this example. For example, the dual-axis mirror unit 5 may include two or more dual-axis mirrors. In the embodiments described above, the laser-induced vibration wave measurement system 20 of the first embodiment was described in which the galvanometer scanner unit 3 and the biaxial mirror unit 5 are combined to sweep either or both of the excitation laser beam and the measurement laser beam, but the system is not limited to this example. For example, either the galvanometer scanner unit 3 or the biaxial mirror unit 5 may be configured to sweep either or both of the excitation laser beam and the measurement laser beam.

[0066] In the embodiment described above, the irradiation location analysis unit 124b of the processing unit 100 obtained the result of selecting the irradiation location based on the laser irradiation location image captured by the imaging device 13, but the example is not limited to this. For example, the result of selecting the irradiation location may be obtained based on information acquired by a device that can acquire surface information of the inspection target M, such as a 3D scanner or thermography. In the embodiment described above, the irradiation area analysis unit 124b of the processing unit 100 selected a laser irradiation area that is flat, free of uneven shadows, has the same wettability as other laser irradiation areas, and has no attached objects, based on the laser irradiation area image. However, this is just one example, and the selection items, criteria, and number of selections can be arbitrarily determined by the user. In the embodiment described above, the data processing unit 126a determined that data in which a certain correlation coefficient or higher is not obtained with the trend, using the exponential function as an evaluation function, contains sudden noise. However, the example is not limited to this. For example, the reverberation monitor 7 may be used to measure ambient sound. The data processing unit 126a of the processing unit 100 may remove noise components contained in the vibration data based on the ambient sound measured by the reverberation monitor 7. Alternatively, the laser-induced vibration wave measurement system 20 may be equipped with a vibration measuring device that measures the vibration of the laser-induced vibration wave measurement system 20 itself. The data processing unit 126a of the processing unit 100 may then remove noise components contained in the vibration data based on the vibration measured by the vibration measuring device. In the embodiment described above, the determination unit 126b determines the integrity of the area irradiated with the excitation laser beam using the results of an FFT analysis performed by the data processing unit 126a on the vibration data. However, the invention is not limited to this example. For example, the determination unit 126b may determine the integrity of the area irradiated with the excitation laser beam using the results of a wavelet analysis performed by the data processing unit 126a. In the embodiment described above, machine learning may be applied to the processing of the information processing unit 120.

[0067] According to the laser-induced vibration wave measurement system 20 of the first embodiment, the laser-induced vibration wave measurement system 20 measures the object to be inspected M based on the vibrations generated when the object to be inspected M is irradiated with an excitation laser beam. The laser-induced vibration wave measurement system 20 includes a laser device that irradiates excitation laser beam, a focusing position derivation unit that derives an adjustment amount for the focusing position of an excitation laser focusing unit that focuses the excitation laser beam based on the distance between the laser device and the irradiation point of the excitation laser beam, and a communication unit that transmits control information including information indicating the adjustment amount to the excitation laser focusing unit. By configuring it in this way, the focusing diameter of the excitation laser beam output from the excitation laser focusing unit can be reduced, thereby improving the irradiation intensity per unit area of ​​the excitation laser beam. Since the signal intensity in the frequency spectrum can be improved, the measurement accuracy of the object to be inspected M can be improved.

[0068] Furthermore, the system includes an irradiation location analysis unit that selects the irradiation location based on information representing an image of the area of ​​the inspection target M to be irradiated with the excitation laser beam, and the communication unit transmits control information, including information indicating the irradiation location selected by the irradiation location analysis unit, to a sweeping device that sweeps the excitation laser beam. By configuring the system in this way, noise caused by irradiating areas where the vibration laser light should not be applied can be reduced, thereby improving the measurement accuracy of the object M being inspected. Furthermore, the system includes a reverberation data acquisition unit 122c that acquires time-series data of reverberation sound generated when the inspection target M is irradiated with excitation laser light, and a reverberation analysis unit 124c that acquires the timing for irradiating the inspection target M with excitation laser light based on the intensity of the reverberation sound in the time-series data of reverberation sound acquired by the reverberation data acquisition unit 122c. The communication unit transmits control information, including information indicating the timing acquired by the reverberation analysis unit 124c, to the excitation laser device 1 that irradiates the inspection target M with excitation laser light. By configuring the system in this way, the reverberation analysis unit can acquire timings in which the time range in which the reverberation intensity is below the reverberation threshold widens, based on the reverberation intensity of the time-series data of reverberation, and transmit control information including information indicating the acquired timings to the excitation laser device 1. The excitation laser device 1 receives the control information and irradiates the excitation laser light at the timings included in the received control information. Since the excitation laser device 1 can irradiate the excitation laser light at timings in which the time range with less influence from reverberation widens, it can reduce the influence of reverberation that occurs when the irradiation period of the excitation laser light is short. Since the noise component of the amplitude waveform with respect to time, which represents the vibrations that occur when the excitation laser light is irradiated onto the inspection target M, can be reduced, the measurement accuracy of the inspection target M can be improved. Furthermore, the system includes a data removal unit that removes data from the measurement data of vibrations occurring on the object M being inspected, specifically data from the time the excitation laser beam was irradiated onto the object M for a predetermined period of time. This configuration reduces the influence of noise that occurs immediately after irradiation with the excitation laser beam, thereby improving the measurement accuracy of the object M being inspected.

[0069] Furthermore, the system includes a noise reduction unit that removes noise from the vibration measurement data based on the correlation coefficient between the vibration measurement data generated in the object under inspection M and the evaluation function of the measurement data. This configuration reduces the impact of suddenly occurring noise, thereby improving the measurement accuracy of the object under inspection M. Furthermore, the system includes a determination unit that determines the soundness of the area of ​​the inspection target M irradiated with the vibration-inducing laser light, based on measurement data acquired when the inspection target M is irradiated with vibration-inducing laser light and measurement data acquired when the inspection target M is not irradiated with vibration-inducing laser light.By configuring the system in this way, the noise component of the measurement data acquired when the inspection target M is irradiated with vibration-inducing laser light can be reduced based on the measurement data acquired when the inspection target M is not irradiated with vibration-inducing laser light, thereby improving the measurement accuracy of the inspection target M.

[0070] (Second embodiment) (Laser-induced vibration wave measurement system) An example of the laser-induced vibration wave measurement system 20a of the second embodiment can be applied to Figure 1. However, it includes a processing unit 100a instead of processing unit 100. (Processing unit 100a) Figure 18 is a block diagram showing an example of a processing unit for a laser-induced vibration wave measurement system according to a second embodiment. The processing unit 100a is implemented by a device such as a personal computer, server, smartphone, tablet computer, or industrial computer. The processing unit 100a includes, for example, a communication unit 110, an information processing unit 120a, a display unit 130, and a storage unit 140a.

[0071] The information processing unit 120a is a software function unit that is realized, for example, by a processor such as a CPU executing a program 142a stored in the memory unit 140a. Note that all or part of the information processing unit 120a may be realized by hardware such as an LSI, ASIC, or FPGA, or by a combination of software function units and hardware. The information processing unit 120a includes, for example, an information acquisition unit 122, a measurement unit 124, and an analysis unit 126d.

[0072] (Analysis Department 126d) The analysis unit 126d comprises a data processing unit 126c and a determination unit 126b. The data processing unit 126c acquires the measurement conditions output by the timing derivation unit 124d and the vibration data output by the vibration data acquisition unit 122d, and processes the acquired vibration data based on the acquired measurement conditions. Here, the vibration data may be obtained by irradiating the same location on the object M being inspected with a single vibration laser beam, or by irradiating it with multiple beams. However, when using data obtained by irradiating with multiple vibration laser beams, the data processing unit 126c may average or integrate the vibration data output by the vibration data acquisition unit 122d. The data processing unit 126c extracts data for measurement time periods M1, M2, ... from the vibration data based on the measurement conditions output by the timing derivation unit 124d. The data processing unit 126c also removes an arbitrarily determined reduction amount from the maximum displacement of vibration generated by the excitation laser after irradiation with the excitation laser light, from the extracted data for time periods M1, M2, .... Here, an example of the reduction amount is 1 / 10, 1 / 100, etc., and the data is for a predetermined time period such as 0.5ms-10ms. By removing an arbitrarily determined reduction amount from the maximum displacement of vibration generated by the excitation laser after irradiation with the excitation laser light, the influence of noise that occurs immediately after irradiation with the excitation laser light can be reduced, thereby improving measurement accuracy.

[0073] Furthermore, the data processing unit 126c reduces sudden noise from the acquired vibration data. Specifically, the data processing unit 126c reduces the noise component of the acquired vibration data by adding the acquired vibration data with data that has been phase-shifted. Here, the amount of phase shift is predetermined. Figure 19 shows an example of noise reduction in the laser-induced vibration wave measurement system 20a of the second embodiment. In Figure 19, (a) is acoustic noise, (b) is a signal with the phase of the acoustic noise in (a) shifted by π, and (c) is a signal obtained by adding (a) and (b). Returning to Figure 18, we will continue the explanation.

[0074] The data processing unit 126c acquires effective data obtained by reducing the noise component of the vibration data. Here, if the acquired valid data is data obtained by irradiating the same location of the inspection target M with multiple vibration laser beams, the data processing unit 126c removes the noise that was abruptly generated as a result of irradiating the same location with multiple vibration laser beams from the valid data. Specifically, since the number of times that noise abruptly generated as a result of irradiating the same location with multiple vibration laser beams is mixed into the vibration data is small compared to the total number of irradiations, the data processing unit 126c removes data containing noise abruptly generated as a result of irradiating the same location with multiple vibration laser beams by extracting waveforms with a high correlation coefficient with the waveform obtained by averaging the vibration data over time, and then extracting waveforms that are above a threshold. The data processing unit 126c outputs information representing the frequency spectrum to the determination unit 126b.

[0075] The process of adjusting the distance between lenses 12a and 12b of the vibration laser focusing unit 10 and the distance between lenses 12c and 12d of the measurement laser focusing unit 11 can be applied as shown in Figure 14. The process of controlling the irradiation area of ​​the inspection target M using the galvanometer scanner unit 3 and the dual-axis mirror unit 5 can be applied as shown in Figure 15. The process shown in Figure 16 can be applied to control the output timing of the excitation laser beam. An example of the operation of the laser-induced vibration wave measurement system 20a can be applied to Figure 17. However, in step S404, noise is removed from the vibration measurement data based on the vibration measurement data generated in the object under inspection M and the time-series data of the measurement data with a phase shift. In the embodiment described above, machine learning may be applied to the processing of the information processing unit 120a. According to the laser-induced vibration wave measurement system 20a of the second embodiment, the laser-induced vibration wave measurement system 20a measures the inspection target M based on the vibrations generated when the inspection target M is irradiated with an excitation laser beam. The laser-induced vibration wave measurement system 20a comprises a laser device that irradiates excitation laser beams, a focusing position derivation unit that derives an adjustment amount for the focusing position of an excitation laser focusing unit that focuses the excitation laser beams based on the distance between the laser device and the irradiation point of the excitation laser beams, and a communication unit that transmits control information including information indicating the adjustment amount to the excitation laser focusing unit. By configuring it in this way, the focusing diameter of the excitation laser beam output from the excitation laser focusing unit can be reduced, thereby improving the irradiation intensity per unit area of ​​the excitation laser beam. Since the signal intensity in the frequency spectrum can be improved, the measurement accuracy of the inspection target M can be improved. Furthermore, the system includes a noise reduction unit that removes noise from the vibration measurement data based on the vibration measurement data generated in the object M under inspection and the time-series data of the measurement data with a phase shift. By superimposing the vibration measurement data generated in the object M under inspection and the time-series data of the measurement data with a phase shift, at least a portion of the noise components can be canceled out, reducing the effect of noise and thus improving the measurement accuracy of the object M under inspection.

[0076] (Variation 1) (Laser-induced vibration wave measurement system) Modifications of the first and second embodiments will now be described. Modification 1 of the first embodiment comprises one or more housings, each housing containing the elements constituting the laser-induced vibration wave measurement system 20 of the first embodiment. Modification 1 of the second embodiment comprises one or more housings, each housing containing the elements constituting the laser-induced vibration wave measurement system 20a of the second embodiment. Here, as an example, we will continue the description of Modification 1 of the first embodiment.

[0077] Figure 20 shows Example 1 of a modified example 1 of the first embodiment of the laser-induced vibration wave measurement system. As shown in Figure 20, the laser-induced vibration wave measurement system of modified example 1 of the first embodiment comprises three housings. Each of the three housings is referred to as the first housing H01, the second housing H02, and the third housing H03. Preferably, these first housing H01, second housing H02, and third housing H03 are covered with soundproof walls, which will be described later. The first housing H01 houses the excitation laser device 1 and the mirror 8a. The excitation laser device 1 and mirror 8a housed in the first housing H01 are less affected by noise from outside the laser-induced vibration wave measurement system 20 (here, the first housing H01), and therefore have little impact on the measurement system housed in the second housing H02 (described later), and thus have little impact on the measurement results. For this reason, they do not need to be surrounded by soundproof walls. The excitation laser device 1 outputs excitation laser light. The optical path of the excitation laser light output by the excitation laser device 1 is bent by the mirror 8a (bent at a right angle in Figure 20) and proceeds from the laser light port LP01 formed at the boundary between the first housing H01 and the second housing H02 to the second housing. The laser light port LP01 will be described later.

[0078] The second housing H02 is equipped with a measuring laser device 2, a galvanometer scanner unit 3, a mirror 8c, a distance measuring laser device 9, an excitation laser focusing unit 10, and a measuring laser focusing unit 11. Although not shown in Figure 20, the second housing H02 may also be equipped with a reverberation sound monitor 7, a mirror 8b, an imaging device 13, and a processing unit 100. The second housing H02 houses the devices that perform measurement processing, and the noise from outside the laser-induced vibration wave measurement system 20 (in this case, the second housing H02) tends to affect the measurement results. For this reason, it is preferable that the second housing H02 is surrounded by a soundproof wall SW. The excitation laser beam from the first housing H01 passes through the laser beam port LP01 and enters the excitation laser focusing unit 10. The excitation laser focusing unit 10 focuses the excitation laser beam output by the excitation laser device 1. The optical path of the excitation laser beam focused by the excitation laser focusing unit 10 is bent by the mirror 8c (bent at a right angle in Figure 20) and proceeds to the galvanometer scanner unit 3.

[0079] Meanwhile, the measurement laser device 2 outputs measurement laser light to detect vibrations induced in the object being inspected M. The measurement laser focusing unit 11 focuses the measurement laser light output by the measurement laser device 2. The measurement laser light focused by the measurement laser focusing unit 11 proceeds to the galvanometer scanner unit 3. The galvanometer scanner unit 3 adjusts the optical paths of either or both of the excitation laser light and the measurement laser light to any direction and angle. Either or both of the excitation laser light and the measurement laser light output by the galvanometer scanner unit 3 proceed to the third housing from the laser light port LP02 formed at the boundary between the second housing H02 and the third housing H03. The laser light port LP02 will be described later. The third housing H03 is equipped with a biaxial mirror unit 5. The biaxial mirror unit 5 is equipped with a biaxial mirror 6 and adjusts the biaxial mirror 6. The third housing H03 is provided with an output laser light port to guide the laser to the object to be inspected M. Since the biaxial mirror unit 5 is housed in the third housing H03, it is preferable that the third housing H03 is surrounded by a soundproof wall SW. However, if the biaxial mirror unit 5 housed in the third housing H03 is configured to be less susceptible to vibration due to external noise from the laser-induced vibration wave measurement system 20 (in this case, the third housing H03), then it is not necessary for the third housing H03 to be surrounded by a soundproof wall. For example, if the biaxial mirror unit 5 is heavy, and a vibration suppression mechanism is provided, the influence of external noise is reduced, and therefore a soundproof wall SW is not required.

[0080] Figure 20 illustrates a case where the third housing H03 is not covered by a soundproof wall SW and has a dome-shaped (semi-circular) laser light port. The dome-shaped laser light port is preferably made of the same material as the laser window LW described later, and is preferably coated with the same anti-reflective coating. The laser light output to the two-axis mirror unit 5 (at least one or all of the excitation laser light, measurement laser light, and distance measuring laser light) is irradiated from the laser light port formed in the third housing H03 to the outside of the third housing H03, at the irradiation position of the inspection target M set by the two-axis mirror unit 5.

[0081] Figure 21 shows Example 2 of a modified example 1 of the first embodiment of the laser-induced vibration wave measurement system. Example 2 of the modified example 1 of the first embodiment of the laser-induced vibration wave measurement system comprises two housings. The two housings are referred to as the third housing H03 and the fourth housing H04. Figure 21 illustrates the case in which the third housing H03 does not have a dome-shaped (semi-circular) laser light port. Example 2 of the laser-induced vibration wave measurement system, which is a modified example of the first embodiment, integrates the first housing H01 and the second housing H02 of Example 1 shown in Figure 20. That is, the fourth housing H04 integrates the first housing H01 and the second housing H02 of Example 1 shown in Figure 20. The fourth housing H04 is equipped with a vibration laser device 1, a mirror 8a, a measurement laser device 2, a galvanometer scanner unit 3, a mirror 8c, a distance measuring laser device 9, a vibration laser focusing unit 10, and a measurement laser focusing unit 11. Although not shown in Figure 21, the fourth housing H04 may also be equipped with a reverberation sound monitor 7, a mirror 8b, an imaging device 13, and a processing unit 100. Since the fourth housing H04 houses the devices that perform measurement processing, it is preferable that it is surrounded by a soundproof wall SW. At least one or all of the excitation laser beam, measurement laser beam, and distance measurement laser beam output by the galvanometer scanner unit 3 travel from the laser light port LP03 formed at the boundary between the fourth housing H04 and the third housing H03 to the third housing H03. The laser light port LP03 will be described later. In Example 2 of the laser-induced vibration wave measurement system, Modification 1 of the First Embodiment, the excitation laser device 1 is housed in the fourth housing H04, so vibrations originating from the excitation laser may affect the device that performs the measurement processing. For this reason, in Example 2 of the laser-induced vibration wave measurement system, Modification 1 of the First Embodiment, it is preferable to use a high-power laser using a semiconductor laser (LD: Laser Diode) excitation method, which is quieter than the flash lamp excitation method, as the excitation laser device 1.

[0082] Figure 22 shows Example 3 of the laser-induced vibration wave measurement system, Modification 1 of the First Embodiment. Example 3 of the laser-induced vibration wave measurement system, Modification 1 of the First Embodiment, integrates the first housing H01, the second housing H02, and the third housing H03 in Example 1 of the laser-induced vibration wave measurement system, Modification 1 of the First Embodiment, or integrates the fourth housing H04 and the third housing H03 in Example 2 of the laser-induced vibration wave measurement system, Modification 1 of the First Embodiment. The housing that integrates the first housing H01, the second housing H02, and the third housing H03, or the housing that integrates the fourth housing H04 and the third housing H03, is called the fifth housing H05. The fifth housing H05 is equipped with a vibration laser device 1, a mirror 8a, a measurement laser device 2, a galvanometer scanner unit 3, a mirror 8c, a distance measuring laser device 9, a vibration laser focusing unit 10, a measurement laser focusing unit 11, and a two-axis mirror unit 5. Although not shown in Figure 22, the fifth housing H05 may also be equipped with a reverberation sound monitor 7, a mirror 8b, an imaging device 13, and a processing unit 100. Since the fifth housing H05 houses the devices that perform measurement processing, it is preferable that it is surrounded by a soundproof wall SW. The dual-axis mirror unit 5 is equipped with a dual-axis mirror 6 and adjusts the dual-axis mirror 6. The laser light output to the dual-axis mirror unit 5 (at least one or all of the excitation laser light, measurement laser light, and distance measuring laser light) is irradiated from the laser light port LP04 formed in the fifth housing H05 to the outside of the fifth housing H05, at the irradiation position of the inspection target M set by the dual-axis mirror unit 5.

[0083] (Laser light port) The laser optical ports shown in Examples 1 to 3 of the laser-induced vibration wave measurement system of Modification 1 of the First Embodiment will now be described. Here, any of the first housing H01, second housing H02, third housing H03, fourth housing H04, and fifth housing H05 will be referred to as housing H. Also, the laser optical ports LP01, LP02, LP03, and LP04 have the same configuration. Any of the laser optical ports LP01, LP02, LP03, and LP04 will be referred to as laser optical port LP. Figures 23A and 23B show examples of the laser optical port LP shown in Examples 1 to 3 of the laser-induced vibration wave measurement system, which is a modified example of the first embodiment. Figure 23A is a side view of the laser optical port LP of a laser-induced vibration wave measurement system according to Modification 1 of the first embodiment. The laser light port LP comprises a spacer SP, a laser window LW, and a retaining plate PP. The spacer SP is bolted to the housing H. Here, the spacer SP is bolted to the housing H, or, instead of being bolted to the housing H, it is preferably welded to the housing H. The laser window LW is preferably made of a material that has high transmittance of laser light, can withstand high-intensity laser light, and also possesses weather resistance, mechanical rigidity, and chemical stability. An example of a laser window LW is quartz glass. It is desirable that the laser window LW be coated with an anti-reflective film to suppress reflection at the refractive index interface. To prevent the measurement from being affected by the reflection of the measurement laser light at the refractive index interface, it is desirable to set the laser window LW at an angle of several degrees (hereinafter referred to as the "installation angle") with respect to the direction perpendicular to the direction of propagation. However, the laser window LW may also be parallel to the direction perpendicular to the direction of propagation, i.e., the installation angle may be 0 degrees. The installation angle is preferably 5 to 12 degrees, and more preferably 8 to 10 degrees. For example, the installation angle is 10 degrees. The pressing plate PP is a member for fixing the laser window LW to the spacer SP. FIG. 23B is a front view of the laser light port LP of the laser-induced vibration wave measurement system according to Modification 1 of the first embodiment. FIG. 23B is a view seen from the direction of arrow E in FIG. 23A. According to FIG. 23B, an opening is formed in the housing H, and the laser window LW is fixed by the spacer SP having the formed opening and the pressing plate PP having the formed opening so that the laser window LW is exposed from the formed opening. In FIGS. 23A and 23B, the case where the portion where the laser window LW is exposed is circular is shown, but it is not limited to this example. For example, the portion where the laser window LW is exposed may be an ellipse, a rectangle such as a square, or a polygon.

[0084] (Range of installation angle) Here, the desirable range of the installation angle of the laser window LW will be described. FIG. 24 is a diagram for explaining the minimum angle of the installation angle of the laser window LW, and FIG. 25 is a diagram for explaining the maximum angle of the installation angle of the laser window LW. The range of the installation angle is preferably such that, as shown in FIG. 24, the "laser light emitted from the laser device" does not overlap with the "laser light reflected by the laser window LW" at an angle greater than (ΔD>d + d'), and the laser device is at the position where the laser light is emitted, and as shown in FIG. 25, the opening diameter through which the "laser light emitted from the laser device" can pass is ensured (2d'<A') at an angle or less. That is, when the installation angle is θ, the formula (1) holds.

[0085] <00,00581>

Equation

[0086] In equation (1), angles are expressed in radians. By replacing π / 2 in equation (1) with 90 degrees, the expression can be changed to degrees. d is the beam radius of the laser light, L is the distance from the laser device to the laser window LW, Ldis is the distance from the laser device to the laser light emission position after reflection from the laser window LW, and θLaser is the laser divergence angle. Here, θLaser can be ignored if the light is parallel and travels in a straight line without spreading or focusing. Also, θ is the installation angle of the laser window LW, and the angle directly facing the laser beam is defined as 0 degrees. A is the diameter of the laser window LW. Equation (1) can be simplified to the case of parallel light (where θ laser can be ignored), as shown in equation (2).

[0087]

number

[0088] In the modified example 1 of the first embodiment, the shape of the housing H is not limited to a rectangular parallelepiped, but any shape can be applied. Furthermore, the device housed in the housing H can also be arbitrarily changed. Here, as an example, we have described a case in which the laser-induced vibration wave measurement system 20 of the first embodiment is housed in one or more housings, but this is not limited to that. For example, the same effect can be obtained when the laser-induced vibration wave measurement system 20a of the second embodiment is housed in one or more housings. According to Modification 1 of the First Embodiment, the devices constituting the laser-induced vibration wave measurement system 20 are housed in one or more housings H, thereby improving sound insulation performance and thus improving the measurement accuracy of the object to be inspected M.

[0089] (Modification 2) (Laser-induced vibration wave measurement system) The second modified example of the first embodiment of the laser-induced vibration wave measurement system is a system in which the laser-induced vibration wave measurement system 20 of the first embodiment is mounted on a mobile body. Figure 26 shows an example of a laser-induced vibration wave measurement system of Modification 2 of the First Embodiment. As shown in Figure 26, in the laser-induced vibration wave measurement system of Modification 2 of the First Embodiment, the laser-induced vibration wave measurement system 20 of the First Embodiment is mounted on a mobile body such as a truck 500. In addition to the mobile body, Figure 26 also shows a tunnel TU. The mobile body is located inside the tunnel TU. In the example shown in Figure 26, the laser-induced vibration wave measurement system 20 of the First Embodiment is mounted on a truck 500. Specifically, the truck 500 is equipped with an equipment storage unit 250, an equipment housing 300, and a two-axis mirror housing 400. The equipment storage unit 250 houses the power supplies for the devices included in the laser-induced vibration wave measurement system 20, namely the excitation laser device 1, the measurement laser device 2, the galvanometer scanner unit 3, the two-axis mirror unit 5, the reverberation sound monitor 7, the distance measuring laser device 9, the excitation laser focusing unit 10, the measurement laser focusing unit 11, the imaging device 13, and the processing unit 100, as well as the cooling water chiller and the processing unit 100. Since the devices stored in the equipment storage unit 250 may be sources of noise and heat, it is desirable that they be stored in an external enclosure separate from the device housing 300. The devices stored in the equipment storage unit 250 do not need to be managed as warehouses, but it is desirable that they be protected from rain and wind. Since the devices stored in the equipment storage unit 250 may be sources of heat, it is preferable that the equipment storage unit 250 be equipped with either a ventilation function or an air conditioning function, or both.

[0090] The device housing 300 houses the excitation laser device 1, the measurement laser device 2, the galvanometer scanner unit 3, the reverberation sound monitor 7, mirrors 8a, 8b, and 8c, the distance measuring laser device 9, the excitation laser focusing unit 10, the measurement laser focusing unit 11, and the imaging device 13. The device housing 300 is preferably surrounded by a soundproof wall SW. Furthermore, it is desirable that the device housing 300 has dustproof and moistureproof functions.

[0091] However, since the vibration laser device 1 generates noise during operation, it is preferable to separate it from the device housing 300 and house it in a different housing. When the vibration laser device 1 is separated from the device housing 300 and housed in a different housing, the vibration laser light output by the vibration laser device 1 may be sent to the device housing 300 where the measurement laser device 2 and the like are housed, using a mirror 8a. For example, as shown in Example 1 of the modified example 1 above (Figure 20), a configuration is provided in which the vibration laser device 1 is housed in a different housing from the device that performs measurement processing. The twin-axis mirror housing 400 houses the twin-axis mirror unit 5. Preferably, the twin-axis mirror housing 400 is surrounded by a soundproof wall SW. Furthermore, it is desirable that the twin-axis mirror housing 400 has dustproof and moistureproof functions. Figure 26 illustrates an example in which the twin-axis mirror unit 5 is housed in a twin-axis mirror housing 400 separate from the device housing 300, but the invention is not limited to this, and the twin-axis mirror unit 5 may be housed inside the device housing 300, as in Example 3 of Modification 1 (Figure 22) mentioned above.

[0092] Typically, the laser-induced vibration wave measurement system of Modification 2 of the First Embodiment is a system in which the laser-induced vibration wave measurement system 20 housed in the housing H (H01, H02, H03, H04, H05) of Modification 1 of the First Embodiment (Examples 1, 2, and 3), and the equipment storage 250 are mounted on a truck 500.

[0093] In the second modified example of the first embodiment of the laser-induced vibration wave measurement system, the biaxial mirror unit 5 housed in the biaxial mirror housing 400 irradiates the inner wall of the tunnel TU with excitation laser light and measurement laser light. The biaxial mirror unit 5 sweeps the excitation laser light and measurement laser light according to a preset sweep sequence.

[0094] In Modification 2 of the First Embodiment, the case in which the laser-induced vibration wave measurement system 20 is mounted on a truck 500 was described, but the invention is not limited to this example. The laser-induced vibration wave measurement system 20 may be configured to be movable by conventionally known methods. The means of movement is not limited to the presence or absence of wheels. For example, the laser-induced vibration wave measurement system 20 may be mounted on a mobile body such as a handcart, automobile, or railway vehicle. Alternatively, the laser-induced vibration wave measurement system 20 may be made movable by attaching means of movement (e.g., wheels) to it.

[0095] In the second modification of the first embodiment, the case in which the power supply of the laser-induced vibration wave measurement system 20 is mounted on the same mobile body as the device housing 300 and the dual-axis mirror housing 400 was described, but the invention is not limited to this example. For example, the power supply of the laser-induced vibration wave measurement system 20 may be mounted on a mobile body different from the mobile body on which the device housing 300 and the dual-axis mirror housing 400 are mounted. When the power supply of the laser-induced vibration wave measurement system 20 is mounted on a mobile body different from the mobile body on which the device housing 300 and the dual-axis mirror housing 400 are mounted, it is preferable that the mobile body on which the power supply is mounted is equipped with vibration countermeasures.

[0096] Here, as an example, the case in which the laser-induced vibration wave measurement system 20 of the first embodiment is mounted on a mobile body has been described, but this is not limited to that. For example, the same effect can be obtained when the laser-induced vibration wave measurement system 20a of the second embodiment is mounted on a mobile body. According to Modification 2 of the First Embodiment, the laser-induced vibration wave measurement system 20 can be mounted on a mobile body, making it easy to move, and thus facilitating the measurement of the object to be inspected M.

[0097] (Variation 3) (Laser-induced vibration wave measurement system) Modification 3 of the first and second embodiments will now be described. Modification 3 of the first embodiment is equipped with a soundproof wall around some or all of the components constituting the laser-induced vibration wave measurement system 20 of the first embodiment. Modification 1 of the second embodiment is equipped with a soundproof wall around some or all of the components constituting the laser-induced vibration wave measurement system 20a of the second embodiment. In other words, the laser-induced vibration wave measurement system of Modification 1 (Examples 1, 2, and 3) described above, that is, the elements constituting the laser-induced vibration wave measurement system 20 are housed in one or more housings H, and a soundproof wall is equipped around some or all of the housings H (H01, H02, H03, H04, H05). Here, as an example, we will continue the description of Modification 3 of the first embodiment. Figure 27A shows an example of a laser-induced vibration wave measurement system according to Modification 3 of the first embodiment. Figure 27A shows a top view of the laser-induced vibration wave measurement system according to Modification 3 of the first embodiment. As shown in Figure 27A, the laser-induced vibration wave measurement system 20 is covered on all four sides by soundproof walls SW. To improve soundproofing performance, it is preferable to provide soundproof walls SW above and below the laser-induced vibration wave measurement system 20 in addition to the four sides. In other words, it is preferable that the laser-induced vibration wave measurement system 20 is covered by soundproof walls SW. Figure 27B is a partially enlarged view of a laser-induced vibration wave measurement system of Modification 3 of the first embodiment. Figure 27B shows a partially enlarged view of section A in Figure 27A. The sound barrier SW is composed of sound-absorbing material SM. The sound-absorbing material SM is a component that absorbs sound. An example of sound-absorbing material SM is a porous material such as a sponge. The sound-absorbing material SM tightly covers the laser-induced vibration wave measurement system 20 without any gaps. It is desirable that the sound-absorbing material SM just covers the laser-induced vibration wave measurement system 20, or even slightly protrudes from it. The soundproof wall SW may be constructed including a frame plate FP in addition to the sound-absorbing material SM. The frame plate FP is a plate-shaped member that covers the sound-absorbing material SM. The frame plate FP is pressed against the sound-absorbing material SM and its ends are fixed. For example, it can be fixed with bolts or fasteners. With this configuration, the sound-absorbing material SM is fixed between the laser-induced vibration wave measurement system 20 and the frame plate FP. In order to reflect sound from the outside, the frame plate FP is preferably dense (heavy) and rigid. An example of a frame plate FP is a steel plate.

[0098] Figure 28A shows an example 1 of the effect of a sound barrier on a laser-induced vibration wave measurement system in a modified example 3 of the first embodiment. In the example shown in Figure 28A, the results of measuring sound pressure are shown with and without the sound barrier SW installed around the laser-induced vibration wave measurement system 20 of the first embodiment. In the evaluation shown in Figure 28A, the measurement laser device 2, galvanometer scanner unit 3, mirror 8c, distance measuring laser device 9, vibration laser focusing unit 10, and measurement laser focusing unit 11 were housed in a suitable enclosure (the second enclosure H02 mentioned above), and soundproofing wall SW was installed to cover the perimeter (side walls) of the enclosure. The bottom surface of the enclosure was in close contact with the installation floor, and the top surface of the enclosure was topped with the first enclosure H01 as shown in Figure 20 mentioned above. No soundproofing wall SW was placed around the vibration laser device 1 or the two-axis mirror unit 5. The sound insulation targets were the irradiation sound of the laser light (typically a vibration laser) and noise generated in the external environment (such as the sound of passing cars and the operating sounds of equipment such as the laser device power supply and cooling water generating chiller). A microphone was installed inside the enclosure of the laser-induced vibration wave measurement system 20 (second enclosure H02), and the sound range in the range of 0.01kHz to 20kHz was the target of measurement. Figure 28A shows that by installing a sound barrier SW around the laser-induced vibration wave measurement system 20, the sound insulation performance can be improved by approximately 35 dB.

[0099] Figure 28B shows an example 2 of the effect of a sound barrier on a laser-induced vibration wave measurement system in a modified example 3 of the first embodiment. In the example shown in Figure 28B, the results of measuring sound pressure are shown when a single sound barrier SW is installed around the laser-induced vibration wave measurement system 20 of the first embodiment, when two sound barriers are installed, and when no sound barrier is installed. In the evaluation shown in Figure 28B, the measurement laser device 2, galvanometer scanner unit 3, mirror 8c, distance measuring laser device 9, vibration laser focusing unit 10, and measurement laser focusing unit 11 were housed in a suitable enclosure (the second enclosure H02 mentioned above), and soundproofing wall SW was installed to cover the perimeter (side walls) of the enclosure. The bottom surface of the enclosure was in close contact with the installation floor, and the top surface of the enclosure was topped with the first enclosure H01 as shown in Figure 20 mentioned above. No soundproofing wall SW was placed around the vibration laser device 1 and the two-axis mirror unit 5. The sound insulation target was a single tone sound source at 0.1 kHz. A microphone was installed inside the enclosure of the laser-induced vibration wave measurement system 20, and 0.1 kHz was used as the measurement target. According to Figure 28B, it can be seen that by installing a single layer of soundproofing wall SW around the laser-induced vibration wave measurement system 20 (second enclosure H02), the sound insulation performance can be improved by approximately 21.6 dB. Furthermore, it was found that installing two soundproof walls SW improves sound insulation performance by approximately 13.3 dB. Here, installing a single soundproof wall SW resulted in improved sound insulation performance compared to installing two soundproof walls SW around the laser-induced vibration wave measurement system 20. This is presumed to be because when two soundproof walls SW are installed, the additional soundproof wall SW resonates and vibrates. From this, it can be concluded that sound insulation performance can be improved by installing a single soundproof wall with high sound insulation performance, or by considering the resonant vibration of the soundproof wall SW.

[0100] Figure 29 shows an example 3 of the effect of a sound barrier on a laser-induced vibration wave measurement system, which is a modified example 3 of the first embodiment. In the example shown in Figure 29, the results of measuring sound pressure are shown with and without the sound barrier SW installed around the laser-induced vibration wave measurement system 20 of the first embodiment. In the evaluation shown in Figure 29, the two-axis mirror unit 5 was housed in a suitable enclosure (the third enclosure H03 mentioned above), and soundproof walls SW were installed to cover the perimeter (side walls) and top surface of the enclosure. The bottom surface was placed on the floor. The measurement laser device 2, galvanometer scanner unit 3, mirror 8c, distance measuring laser device 9, vibration laser focusing unit 10, measurement laser focusing unit 11, and vibration laser device 1 were housed in suitable enclosures (the first enclosure H01 and second enclosure H02 described later), with soundproof walls placed around them. The target of sound insulation was the sound of laser irradiation. A microphone was installed inside the third enclosure H03, and the sound range in the 0kHz to 20kHz range was the target of measurement. As shown in Figure 29, it can be seen that the sound insulation performance is improved by about 18dB by installing soundproof walls SW around the third enclosure H03.

[0101] According to Modification 3 of the First Embodiment, sound insulation performance can be improved by installing a soundproof wall SW around the laser-induced vibration wave measurement system 20, thereby improving the measurement accuracy of the object of inspection M. Here, as an example, we have described the case in which a sound barrier SW is provided around the laser-induced vibration wave measurement system 20 of the first embodiment, but this is not limited to that. For example, the same effect can be obtained when a sound barrier SW is provided around the laser-induced vibration wave measurement system 20a of the second embodiment.

[0102] (Operation of the laser-induced vibration wave measurement system 20) Figure 30 is a sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment. Figure 30 shows the process from adjusting the focusing position of the excitation laser focusing unit 10, to controlling the laser irradiation point on the inspection target M using the galvanometer scanner unit 3 and the biaxial mirror unit 5, and finally irradiating the laser. In other words, the process described here involves linking Figures 14 and 15 of the first embodiment. Figures 14 and 15 will be referenced as appropriate. (Step S501) The irradiation area is specified. (Step S502) Steps S101 and S102 in Figure 14 are executed. (Step S503) The communication unit 110 of the processing unit 100 receives irradiation distance information transmitted by the distance measuring laser device 9 and outputs the received irradiation distance information to the information acquisition unit 122. The irradiation distance data acquisition unit 122a of the information acquisition unit 122 acquires the irradiation distance information output by the communication unit 110 and outputs the acquired irradiation distance information to the measurement unit 124. The focusing position derivation unit 124a of the measurement unit 124 acquires the irradiation distance information output by the irradiation distance data acquisition unit 122a and obtains the inter-lens distance between lens 12a and lens 12b associated with the acquired irradiation distance information from the inter-lens distance table 144 stored in the storage unit 140. The communication unit 110 of the processing unit 100 receives irradiation distance information transmitted by the distance measuring laser device 9 and outputs the received irradiation distance information to the information acquisition unit 122. The irradiation distance data acquisition unit 122a of the information acquisition unit 122 acquires the irradiation distance information output by the communication unit 110 and outputs the acquired irradiation distance information to the measurement unit 124. The focusing position derivation unit 124a of the measurement unit 124 acquires the irradiation distance information output by the irradiation distance data acquisition unit 122a and obtains the inter-lens distance between lens 12c and lens 12d associated with the acquired irradiation distance information from the inter-lens distance table 144 stored in the storage unit 140. The light-gathering position deriving unit 124a determines whether the acquired distance range is within the range where light can be gathered by lenses 12a, 12b, 12c, and 12d.

[0103] (Step S504) The focusing position deriving unit 124a outputs an error if it determines that the distance is outside the range where focusing is possible. The focusing position deriving unit 124a may also display an error on the display unit 130. (Step S505) The light-gathering position guide unit 124a determines whether to continue the inspection. If the inspection is to be continued, the process proceeds to step S501. If the inspection is not to be continued, the process ends. (Step S506) If it is determined in step S503 that the distance range is within which light can be collected, steps S101 to S111 in Figure 14 are executed. (Step S507) Steps S201 to S204 in Figure 15 are executed. (Step S508) The irradiation area analysis unit 124b of the processing unit 100 determines whether or not there are any areas that can be irradiated with a laser. If there are no areas that can be irradiated with a laser, the process proceeds to step S504. (Step S509) If it is determined in step S508 that there are no areas that can be irradiated with a laser, then steps S205 to S206 in Figure 15 are executed.

[0104] (Step S510) The irradiation area analysis unit 124b of the processing unit 100 determines whether or not there are areas where the amount of dirt or moisture is significantly different from other areas. (Step S511) If, in step S510, the irradiation area analysis unit 124b determines that there is a significant difference in dirt or moisture in one area compared to other areas, it displays a warning on the display unit 130. (Step S512) If, in step S510, it is determined that there are no areas where dirt or moisture differs significantly from other areas, the irradiation area analysis unit 124b determines whether or not there is a sweeping route that avoids areas where laser irradiation is not possible. If there is no sweeping route that avoids areas where laser irradiation is not possible, the process terminates. (Step S513) In step S511, if a warning is displayed on the display unit 130, or in step S512, if a sweep route exists that avoids areas where laser irradiation is not possible, the excitation laser device 1 irradiates excitation laser light, and the measurement laser device 2 irradiates measurement laser light. In steps S501 to S513, any of the steps may be omitted or the order of the steps may be changed.

[0105] (Operation of the laser-induced vibration wave measurement system 20) Figure 31 is a sequence chart showing an example of the operation of the laser-induced vibration wave measurement system of the first embodiment. Figure 31 shows the process of determining whether the area of ​​the inspection target M irradiated with the excitation laser light is sound or not by controlling the output timing of the excitation laser light, irradiating with the excitation laser light and the measurement laser light, and processing the vibration data. In other words, the process of linking Figures 16 and 17 of the first embodiment will be described. Here, Figures 2, 16, and 17 will be referenced as appropriate. (Step S601) The reverberation sound analysis unit 124c of the processing unit 100 specifies the measurement range S0-1. (Step S602) The reverberation sound analysis unit 124c of the processing unit 100 specifies the number of irradiation pulses p of the measurement laser light. (Step S603) The reverberation sound analysis unit 124c of the processing unit 100 specifies the number a of the 203 measurement areas. (Step S604) Steps S301 to S307 in Figure 16 are executed. (Step S605) The reverberation analysis unit 124c of the processing unit 100 determines whether or not there is a time domain in which the reverberation noise is reduced.

[0106] (Step S606) The reverberation analysis unit 124c outputs an error if it determines that there is no time domain in which reverberation noise is reduced. The reverberation analysis unit 124c may also display the error on the display unit 130. (Step S607) The reverberation analysis unit 124c determines whether to continue the inspection. If the inspection is to continue, the process proceeds to step S601. (Step S608) If the inspection is not continued, the display unit 130 displays the inspection result for the soundness of the portion of the inspection target M that was irradiated with the excitation laser light. (Step S609) If it is determined in step S605 that there is a time domain in which the reverberation noise is reduced, the timing derivation unit 124d sets i=0. (Step S610) The timing derivation unit 124d is set to j=1.

[0107] (Step S611) The timing derivation unit 124d determines whether i > p. (Step S612) When i ≥ p, the excitation laser device 1 emits excitation laser light, and the measurement laser device 2 emits measurement laser light. (Step S613) The communication unit 110 of the processing unit 100 receives vibration data (vibration amount) transmitted by the measuring laser device 2 and outputs the received vibration data to the information acquisition unit 122. The vibration data acquisition unit 122d of the information acquisition unit 122 acquires the vibration data output by the communication unit 110. The vibration data acquisition unit 122d outputs the acquired vibration data to the analysis unit 126. (Step S614) The timing derivation unit 124d sets i = i + 1 and returns to step S611. (Step S615) Steps S401 to S404 in Figure 17 are executed.

[0108] (Step S616) The data processing unit 126a determines whether j > a. If j > a, the process proceeds to step S607. (Step S617) The timing derivation unit 124d moves the measurement area. For example, the timing derivation unit 124d moves from the biaxial mirror irradiation area 203-1 to the biaxial mirror irradiation area 203-2. (Step S618) The timing derivation unit 124d sets j = j + 1 and proceeds to step S611. In steps S601 to S609, any of the steps may be omitted or the order of the steps may be changed.

[0109] Here, the operation of the laser-induced vibration wave measurement system 20 of the first embodiment has been described as an example, but it is not limited to this. For example, the same applies to the laser-induced vibration wave measurement system 20a of the second embodiment, or to modifications of the laser-induced vibration wave measurement system 20 of the first embodiment or the second embodiment of the laser-induced vibration wave measurement system 20a of the second embodiment.

[0110] Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. Furthermore, the aforementioned processing unit 100 and processing unit 100a each have a computer inside. The processes of each of the aforementioned devices are stored in program form on a computer-readable recording medium, and the above processes are performed when the computer reads and executes this program. Here, a computer-readable recording medium refers to a magnetic disk, magneto-optical disk, CD-ROM, DVD-ROM, semiconductor memory, etc. Alternatively, this computer program may be distributed to a computer via a communication line, and the computer that receives this distribution may execute the program. Furthermore, the above program may be intended to implement some of the functions described above. Furthermore, the aforementioned functions may be achieved in combination with programs already recorded in the computer system, such as so-called differential files (differential programs). In the embodiments described above, processing unit 100 and processing unit 100a are examples of measuring devices, inspection target M is an example of an inspection target, excitation laser light is an example of a laser, data processing unit 126a and data processing unit 126c are examples of a data removal unit and a noise removal unit, galvanometer scanner unit 3 and biaxial mirror unit 5 are examples of sweeping devices, excitation laser device is an example of a laser device, and galvanometer scanner unit 3 and biaxial mirror unit 5 are examples of sweeping units. [Explanation of Symbols]

[0111] 20, 20a...Laser-induced vibration wave measurement system, 1...Excitation laser device, 2...Measurement laser device, 3...Galvanometer scanner unit, 4a, 4b...Galvanometer scanner mirror, 5...Two-axis mirror unit, 6...Two-axis mirror, 7...Reverberation sound monitor, 8a, 8b, 8c...Mirror, 9...Distance measuring laser device, 10...Excitation laser focusing unit, 11...Measurement laser focusing unit, 12a, 12b, 12c, 12d...Lens, 13...Imaging device, 100, 100a...Processing unit, 110...Communication unit, 120, 120a...Information processing unit, 122...Information acquisition unit, 122a...Irradiation distance data acquisition unit, 122b...Irradiation location data acquisition unit, 122c...Reverberation sound data acquisition unit, 122d...Vibration data acquisition unit, 124...Measurement unit, 124a... Focusing position derivation unit, 124b... Irradiation area analysis unit, 124c... Reverberation sound analysis unit, 124d... Timing derivation unit, 126, 126d... Analysis unit, 126a, 126c... Data processing unit, 126b... Judgment unit, 140, 140a... Storage unit, 142, 142a... Program, 144... Inter-lens distance table, 146... Peripheral measurement data DB, 250... Equipment storage unit, 300... Device housing, 400... Dual-axis mirror housing, 500... Track

Claims

1. A measuring device for measuring concrete based on vibrations generated when laser light is irradiated onto the concrete, A laser device that emits the laser light and a focusing position derivation unit that derives an adjustment amount for the focusing position of a laser focusing unit that focuses the laser light based on the distance between the laser device and the laser light irradiation point, A communication unit that transmits control information including information indicating the adjustment amount to the laser focusing unit, A noise reduction unit that uses predetermined vibration data that decays exponentially with respect to time as an evaluation function, derives a correlation coefficient between this data and measurement data of vibrations generated in the concrete irradiated with laser light, determines that the derived correlation coefficient is below a threshold, and removes it from the measurement data of vibrations. Equipped with, The vibration is generated by the ablation of the concrete surface, according to the measuring device.

2. A measuring device for measuring concrete based on vibrations generated when laser light is irradiated onto the concrete, A laser device that emits the laser light and a focusing position derivation unit that derives an adjustment amount for the focusing position of a laser focusing unit that focuses the laser light based on the distance between the laser device and the laser light irradiation point, An irradiation location analysis unit selects the location to be irradiated with the laser light based on information representing an image of the area of ​​the concrete where the laser light is to be irradiated, A communication unit that transmits control information including information indicating the adjustment amount to the laser focusing unit, A noise reduction unit that uses predetermined vibration data that decays exponentially with respect to time as an evaluation function, derives a correlation coefficient between this data and measurement data of vibrations generated in the concrete irradiated with laser light, determines that the derived correlation coefficient is below a threshold, and removes it from the measurement data of vibrations. Equipped with, The aforementioned vibration was caused by ablation of the concrete surface, The irradiation area analysis unit is a measuring device that uses captured images to identify areas on the concrete surface that are free of attachments, and selects these areas as areas to be irradiated with laser light.

3. Irradiation location analysis unit selects the location to be irradiated with the laser light based on information representing an image of the area of ​​the concrete where the laser light is to be irradiated. Furthermore, The measuring device according to claim 1, wherein the communication unit transmits control information, including information indicating the location to be irradiated with the laser light selected by the irradiation location analysis unit, to a sweeping device that sweeps the laser light.

4. A reverberation sound data acquisition unit acquires time-series data of reverberation sound generated when the laser light is irradiated onto the concrete, A reverberation sound analysis unit acquires the timing for irradiating the concrete with the laser light based on the reverberation sound intensity of the time-series data of the reverberation sound acquired by the reverberation sound data acquisition unit. Furthermore, The aforementioned reverberation includes the sound produced when the laser light is irradiated onto the concrete, and the reverberation of said sound. The measuring device according to any one of claims 1 to 3, wherein the communication unit transmits control information, including information indicating the timing acquired by the reverberation sound analysis unit, to the laser device that irradiates the laser light.

5. A data removal unit removes data from the measurement data of vibrations occurring in the concrete, specifically data from the time the laser light was irradiated onto the concrete to a predetermined time period. The measuring device according to any one of claims 1 to 4, further comprising the above.

6. A noise reduction unit removes noise from the measured vibration data based on the measured vibration data of the concrete and the time-series data of the measured vibration data with a phase shift. The measuring device according to any one of claims 1 to 5, further comprising the above.

7. A determination unit determines the soundness of the area of ​​the concrete irradiated with the laser light, based on measurement data obtained when vibration is induced in the concrete by irradiating it with the laser light, and measurement data obtained when the concrete is not irradiated with the laser light that induces vibration. The measuring device according to any one of claims 1 to 6, further comprising the above.

8. The measuring device according to any one of claims 1 to 7, wherein at least the laser focusing unit is housed in a soundproof enclosure.

9. A measurement system for measuring concrete based on vibrations generated when laser light is irradiated onto the concrete, A vibration laser device that irradiates concrete with vibration-generating laser light, and A vibration laser beam focusing unit that focuses the vibration laser light emitted by the vibration laser device, A measuring device comprising: a vibration-generating laser device; a focusing position derivation unit that derives a first adjustment amount for the focusing position of the vibration-generating laser light focusing unit based on the distance between the vibration-generating laser device and the irradiation point of the vibration-generating laser light emitted by the vibration-generating laser device; and a communication unit that transmits control information including information indicating the first adjustment amount to the vibration-generating laser light focusing unit. A noise reduction unit that uses predetermined vibration data that decays exponentially with respect to time as an evaluation function, derives a correlation coefficient between this data and measurement data of vibrations generated in the concrete irradiated with laser light, determines that the derived correlation coefficient is below a threshold, and removes it from the measurement data of vibrations. Equipped with, The measurement system determines that the vibration is generated by the ablation of the concrete surface.

10. A measurement system for measuring concrete based on vibrations generated when laser light is irradiated onto the concrete, A vibration laser device that irradiates concrete with vibration-generating laser light, and A vibration laser beam focusing unit that focuses the vibration laser light emitted by the vibration laser device, A measuring device comprising: a vibration-generating laser device; a focusing position derivation unit that derives a first adjustment amount for the focusing position of the vibration-generating laser light focusing unit based on the distance between the vibration-generating laser device and the irradiation location of the vibration-generating laser light emitted by the vibration-generating laser device; an irradiation location analysis unit that selects the irradiation location based on information representing an image of the location on the concrete to be irradiated with the laser light; a communication unit that transmits control information including information indicating the first adjustment amount to the vibration-generating laser light focusing unit; and a noise reduction unit that uses predetermined vibration data that decays exponentially with respect to the time axis as an evaluation function to derive a correlation coefficient between it and measurement data of vibrations generated in the concrete irradiated with the laser light, determines that the derived correlation coefficient is noise if it is less than a threshold, and removes it from the measurement data of vibrations. Equipped with, The aforementioned vibration was caused by ablation of the concrete surface, The aforementioned irradiation location analysis unit is a measurement system that uses captured images to identify areas on the concrete surface that are free of attachments, and selects these areas as locations to be irradiated with laser light.

11. A measuring laser device that irradiates the concrete with measuring laser light, which is laser light for detecting vibrations induced in the concrete, A measurement laser focusing unit that focuses the measurement laser light emitted by the aforementioned measurement laser device, Equipped with, The focusing position derivation unit derives a second adjustment amount for the focusing position of the measuring laser focusing unit based on the distance between the measuring laser device and the irradiation point of the measuring laser light emitted by the measuring laser device. The measurement system according to claim 9, wherein the communication unit transmits control information including information indicating the second adjustment amount to the measurement laser focusing unit.

12. A measuring laser device that irradiates the concrete with measuring laser light, which is laser light for detecting vibrations induced in the concrete, A measurement laser focusing unit that focuses the measurement laser light emitted by the aforementioned measurement laser device, Equipped with, The focusing position derivation unit derives a second adjustment amount for the focusing position of the measuring laser focusing unit based on the distance between the measuring laser device and the irradiation point of the measuring laser light emitted by the measuring laser device. The measurement system according to claim 11, wherein the communication unit transmits control information including information indicating the second adjustment amount to the measurement laser focusing unit.

13. A sweeping unit that sweeps the excitation laser light output by the excitation laser device and the measurement laser light output by the measurement laser device. The measurement system according to claim 11 or claim 12, further comprising:

14. The measurement system according to any one of claims 9 to 13, wherein at least the vibration-generating laser light focusing unit is housed in a soundproof enclosure.

15. A mobile body equipped with the measurement system according to any one of claims 9 to 14.

16. A measurement method performed by a measuring device for measuring concrete based on vibrations generated when laser light is irradiated onto the concrete, The steps include: deriving an adjustment amount for the focusing position of a laser focusing unit that focuses the laser light, based on the distance between the laser device that irradiates the laser light and the irradiation point of the laser light; The steps include transmitting control information, including information indicating the adjustment amount, to the laser focusing unit, The steps include: using predetermined vibration data that decays exponentially with respect to time as an evaluation function, deriving a correlation coefficient between it and measurement data of vibrations generated in the concrete irradiated with laser light; determining that the derived correlation coefficient is below a threshold, and removing it from the measurement data of vibrations; It has, A measurement method wherein the vibration is generated by ablation of the concrete surface.

17. A measurement method performed by a measuring device for measuring concrete based on vibrations generated when laser light is irradiated onto the concrete, The steps include: deriving an adjustment amount for the focusing position of a laser focusing unit that focuses the laser light, based on the distance between the laser device that irradiates the laser light and the irradiation point of the laser light; A step of selecting the area to be irradiated with the laser light based on information representing an image of the area of ​​the concrete to be irradiated with the laser light, The steps include transmitting control information, including information indicating the adjustment amount, to the laser focusing unit, The steps include: using predetermined vibration data that decays exponentially with respect to time as an evaluation function, deriving a correlation coefficient between it and measurement data of vibrations generated in the concrete irradiated with laser light; determining that the derived correlation coefficient is below a threshold, and removing it from the measurement data of vibrations; It has, The aforementioned vibration was caused by ablation of the concrete surface, The measurement method, in the selection step, involves using the captured image to identify areas on the concrete surface that are free of attachments, and selecting those areas as areas to be irradiated with laser light.

18. A step of transmitting control information, including information indicating the location to be irradiated with the laser light, to a sweeping device that sweeps the laser light. The measurement method according to claim 17, further comprising the above.

19. A step of selecting the area to be irradiated with the laser light based on information representing an image of the area of ​​the concrete to be irradiated with the laser light, The steps include transmitting control information, including information indicating the location to be irradiated with the laser light, to a sweeping device that sweeps the laser light, and The measurement method according to claim 16, further comprising the above.

20. The steps include acquiring time-series data of reverberation sound produced when a laser beam is shone onto concrete at a set interval, and The steps include: obtaining the timing for irradiating the concrete with the laser light based on the reverberation intensity of the time-series data of the reverberation; The steps include transmitting control information, including information indicating the timing, to the laser device that irradiates the laser light, and It further possesses, The measurement method according to any one of claims 16 to 19, wherein the reverberation sound includes the sound produced when the laser light is irradiated onto the concrete and the reverberation sound of said sound.

21. A step of removing data from the measurement data of vibrations occurring in the concrete, specifically data from the time the laser light was irradiated onto the concrete to a predetermined time period. The measurement method according to any one of claims 16 to 20, further comprising the above.

22. A step of removing noise from the measurement data based on the correlation coefficient between the measurement data of vibrations occurring in the concrete and the evaluation function of the measurement data. The measurement method according to any one of claims 16 to 21, further comprising the above.

23. A step of removing noise from the measured vibration data of the concrete, based on the measured vibration data and the time-series data of the measured vibration data with a phase shift. The measurement method according to any one of claims 16 to 22, further comprising the above.

24. A step to determine the soundness of the portion of the concrete irradiated with the laser light, based on measurement data obtained when vibration is induced in the concrete by irradiating it with the laser light, and measurement data obtained when the concrete is not irradiated with the laser light that induces vibration. The measurement method according to any one of claims 16 to 23, further comprising the above.

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