Inspection Equipment

Abstract

To provide an inspection device capable of inspecting an inspection object positioned in a lower layer of a hardly permeable material.SOLUTION: An inspection device includes: a light source for outputting pulse excitation light having a time width from 10 picoseconds to 10 nanoseconds; a nonlinear optical crystal for generating a terahertz wave by the optical wavelength conversion of the excitation light; and a detector for detecting a reflected wave of the terahertz wave reflected by the object to be inspected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an inspection apparatus. [Background technology]

[0002] Patent Document 1 discloses a reflection-type terahertz wave measuring device (inspection device) configured to be able to irradiate the surface of a structure with terahertz waves, a type of electromagnetic wave, and to detect terahertz waves reflected by the structure. This terahertz wave measuring device includes a terahertz wave transmitter as a terahertz wave transmitting means and a terahertz wave detector as a terahertz wave detecting means. In this terahertz wave measuring device, a terahertz wave generating element including a resonant tunneling diode (RTD) or a photoconductive antenna (PCA) is used as the terahertz wave transmitter, and a terahertz wave detecting element consisting of an RTD is used as the terahertz wave transmitter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-26991 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional configuration shown in Patent Document 1, the terahertz wave transmitter is composed of semiconductor elements such as an RTD or PCA, so the terahertz waves emitted by the terahertz wave transmitter are weak and have a small S / N ratio (signal-to-noise ratio), making it difficult to inspect an object located under a difficult-to-permeate material.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an inspection device that can inspect an inspection object located under a difficult-to-permeate material. [Means for solving the problem]

[0006] In order to achieve the above object, the inspection device according to the present disclosure includes: a light source that outputs pulsed excitation light with a time width of 10 picoseconds to 10 nanoseconds; The aforementioned Pulse a nonlinear optical crystal that generates terahertz waves by converting the wavelength of excitation light; a detector that detects a reflected wave of the terahertz wave reflected by an object to be inspected; 、 a condenser lens that condenses the terahertz waves and irradiates the terahertz waves onto the inspection object; a mirror that deflects the terahertz wave from the nonlinear optical crystal at an angle in the range of 45° to 135° with respect to the propagation direction of the terahertz wave; Equipped with 、 The condenser lens is a cylindrical lens provided around the mirror, the mirror is provided rotatably, and the terahertz wave reflected by the mirror is incident on the condenser lens. do. [Effects of the Invention]

[0007] According to the inspection device of the present disclosure, it is possible to inspect an object to be inspected that is located under a layer of a difficult-to-permeate material. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically illustrating the configuration of an inspection device according to a first embodiment. [Figure 2] FIG. 10 is a diagram schematically illustrating the configuration of an inspection device according to a second embodiment. [Figure 3] FIG. 10 is a diagram schematically illustrating the configuration of an inspection device according to a modified example of the second embodiment. [Figure 4] FIG. 10 is a diagram schematically illustrating the configuration of an inspection device according to a third embodiment. [Figure 5] FIG. 10 is a diagram schematically illustrating the configuration of an inspection device according to a modified example of the third embodiment. [Figure 6] FIG. 10 is a diagram schematically illustrating the configuration of an inspection device according to a fourth embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating the configuration of an inspection device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an inspection device according to an embodiment will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative positions, etc. of components described as an embodiment or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0010] [Embodiment 1] [Configuration of inspection device according to embodiment 1] As shown in FIG. 1, the inspection device 1A according to the first embodiment includes a light source 12 that outputs pulsed excitation light LB with a time width of 10 picoseconds to 10 nanoseconds, a nonlinear optical crystal 14 that generates terahertz waves TH by optical wavelength conversion of the excitation light LB, and a detector 16 that detects reflected waves RW of the terahertz waves TH reflected by an inspection target TG. The light source 12 outputs pulsed excitation light LB, and the pulsed excitation light LB is output with a pulse time width of, for example, 1 microsecond or less, preferably 1 nanosecond or less. The light source 12 is, for example, a beam light source such as a chip laser. The nonlinear optical crystal 14 is, for example, a periodically poled lithium niobate (LiNbO3) crystal, which generates terahertz waves TH by backward oscillation of the terahertz waves TH. The terahertz waves TH have a frequency of 10 12 It is an electromagnetic wave in the range of 0.1 to 100 THz (1 trillion hertz).

[0011] The inspection object TG, which is the object to be inspected by the inspection device 1A, is positioned in the direction of propagation of the terahertz wave TH irradiated from the nonlinear optical crystal 14, and the inspection device 1A may be equipped with a half mirror 20 so that the detector 16 can detect the reflected wave RW.

[0012] [Operation of inspection device 1A] In the inspection device 1A according to the first embodiment, when inspecting an inspection object TG, a pulsed excitation light LB having a time width of 10 picoseconds to 10 nanoseconds is output from the light source 12. The pulsed excitation light LB is converted in wavelength to a terahertz wave TH by passing through a nonlinear optical crystal 14, and is then irradiated onto the inspection object TG. The terahertz wave TH irradiated onto the inspection object TG is reflected by the inspection object TG to become a reflected wave RW, which then enters the detector 16. If the inspection device 1A is equipped with a half mirror 20, the direction of the reflected wave RW is changed by the half mirror 20 and the reflected wave RW enters the detector 16. The reflected wave RW that has entered the detector 16 is detected by the detector 16 and is used to inspect the inspection object TG.

[0013] [Effects of Inspection Device 1A] According to the inspection device 1A of the first embodiment, the light source 12 outputs pulsed excitation light LB having a time width of 10 picoseconds to 10 nanoseconds. Therefore, the terahertz wave TH, which has been wavelength-converted by passing through the nonlinear optical crystal 14, is more powerful (higher output) than the terahertz wave emitted from a semiconductor element such as the RTD or PCA described above. Therefore, the light source 12 and the optical component 24, such as the nonlinear optical crystal 14, can be disposed at a position separated from the inspection object TG. For example, the light source 12 and the optical component 24, such as the nonlinear optical crystal 14, can be disposed at a position separated from the inspection object TG by 5 cm or more.

[0014] Furthermore, even if the inspection object TG is covered with a poorly permeable material, the terahertz waves TH pass through the poorly permeable material and are reflected by the inspection object TG. Therefore, even if the inspection object TG is covered with a poorly permeable material, the inspection object TG can be inspected.

[0015] Furthermore, in imaging of difficult-to-penetrate materials, ensuring a high signal-to-noise ratio requires high output from the light source 12. However, continuous wave oscillation, such as with a gyrotron, consumes a lot of power and may burn the object. On the other hand, the light source 12 uses pulsed terahertz waves TH, ensuring high peak power while consuming low power. This allows for non-destructive imaging with high penetration performance without burning the object TG.

[0016] [Embodiment 2] [Configuration of inspection device according to embodiment 2] 2, the inspection device 1B according to the second embodiment includes a condenser lens 22 that condenses the terahertz wave TH between the nonlinear optical crystal 14 and the inspection object TG and irradiates the terahertz wave TH onto the inspection object TG. The other configurations are the same as those of the inspection device 1A according to the first embodiment.

[0017] [Operation of inspection device 1B] In the inspection device 1B according to the second embodiment, when inspecting the inspection object TG, the terahertz waves TH are collected by the collecting lens 22 and irradiated onto the inspection object TG. Therefore, the terahertz waves TH are collected on the inspection object TG, and the reflected waves RW can be detected with high resolution by the detector 16. Other operations, that is, operations until the terahertz waves TH are incident on the collecting lens 22 and operations until the reflected waves RW are detected by the detector 16 and used to inspect the inspection object TG, are the same as those of the inspection device 1A according to the first embodiment.

[0018] [Configuration of Modified Example of Inspection Apparatus 1B] 3, in the inspection device 1B according to the second embodiment, a terahertz wave fiber 36 may be provided between the condenser lens 22 and the inspection target TG. The terahertz wave fiber 36 is a transmission path for transmitting the terahertz wave TH, and has excellent flexibility.

[0019] [Operation of the Modified Example of Inspection Apparatus 1B] In the inspection device 1B described above, the terahertz wave TH is irradiated onto the inspection object TG at an arbitrary position through the terahertz wave fiber 36, and the reflected wave RW reflected by the inspection object TG is detected by the detector 16 through the terahertz wave fiber 36. Therefore, the inspection object TG at an arbitrary position can be inspected.

[0020] [Embodiment 3] [Configuration of inspection device according to embodiment 3] As shown in Fig. 4, the inspection device 1C according to the third embodiment includes a mirror 18 that reflects the terahertz waves TH from the nonlinear optical crystal 14 at an angle of 90° or less relative to the direction of propagation of the terahertz waves TH. For example, in the example shown in Fig. 4, the mirror 18 deflects the terahertz waves TH from the nonlinear optical crystal 14 at an angle of 90° relative to the direction of propagation of the terahertz waves TH. The other configurations are the same as those of the inspection device 1B according to the second embodiment.

[0021] [Operation of inspection device 1C] In the inspection device 1C according to the third embodiment, when inspecting the inspection object TG, the terahertz wave TH is reflected by the mirror 18. Therefore, it is possible to inspect the inspection object TG placed at any position at an angle of 90° or less with respect to the traveling direction of the terahertz wave TH. The other operations, i.e., the operations up to when the terahertz wave TH is incident on the mirror 18 and the operations up to when the reflected wave RW is detected by the detector 16 and used to inspect the inspection object TG, are the same as those of the inspection device 1B according to the second embodiment.

[0022] [Configuration of Modified Example of Inspection Apparatus 1C] 5, in an inspection apparatus 1C according to the fifth embodiment, the condenser lens 22 may be a cylindrical lens 38. The cylindrical lens 38 is disposed with the mirror 18 at its center.

[0023] [Operation of the Modified Example of the Inspection Apparatus 1C] In the inspection device 1C described above, the terahertz waves TH reflected by the mirror 18 are collected by the cylindrical lens 38 and irradiated onto the inspection object TG. As a result, when the inspection object TG has an inner peripheral surface of a cylindrical shape, the inspection object TG can be inspected simply by rotating the mirror 18.

[0024] [Embodiment 4] [Configuration of inspection device according to embodiment 4] 6, the inspection device 1D according to the fourth embodiment includes a data logger 34 that stores data on the reflected wave RW detected by the detector 16. A trigger signal TS is transmitted to the data logger 34 simultaneously with the output of the excitation light LB from the light source 12, and the data logger 34 is configured to store data on the reflected wave RW upon receiving the trigger signal TS. The other configurations are the same as those of the inspection devices 1A, 1B, and 1C according to the first to third embodiments.

[0025] [Operation of inspection device 1D] In the inspection device 1D according to the fourth embodiment, when inspecting the inspection target TG, the data logger 34 stores the data of the reflected wave RW detected by the detector 16 when it receives a trigger signal TS transmitted simultaneously with the output of the excitation light LB from the light source 12. Therefore, the amount of data of the reflected wave RW stored in the data logger 34 can be reduced compared to when the data logger 34 continuously stores the data of the reflected wave RW. Other operations, that is, operations until the reflected wave RW is detected by the detector 16, are the same as those of the inspection devices 1A, 1B, and 1C according to the first to third embodiments.

[0026] [Embodiment 5] [Configuration of inspection device according to embodiment 5] The inspection target TG of the inspection device 1E according to the fifth embodiment is, for example, an iron pipe SP. The inner surface of the iron pipe SP is lined with a resin material RM, and when the resin material RM deteriorates, water penetrates and corrodes the inner wall of the iron pipe SP. The inspection device 1E according to the fifth embodiment aims to inspect the extent of corrosion of the inner wall of the iron pipe SP.

[0027] 7, the inspection device 1E according to the fifth embodiment includes a housing 26 that houses the light source 12, the nonlinear optical crystal 14, and the detector 16, and an arm mechanism 28 that houses the mirror 18 and the condenser lens 22. The arm mechanism 28 has one end where the mirror 18 is provided and the other end where the condenser lens 22 is provided, and one end of the arm mechanism 28 is rotatably attached to the housing 26. The arm mechanism 28, whose one end is rotatably attached, is rotated by an actuator such as a motor (not shown).

[0028] The light source 12 and the nonlinear optical crystal 14 are disposed so that the terahertz waves TH emitted from the nonlinear optical crystal 14 pass through the rotation center of an arm mechanism 28, and are housed in a housing 26. The mirror 18 is disposed at the rotation center of the arm mechanism 28 and is housed in the arm mechanism 28. The condenser lens 22 is disposed on the optical path of the terahertz waves TH reflected by the mirror 18, and is housed in the arm mechanism 28.

[0029] For example, the housing 26 is cylindrical, and a multi-axis arm 30 is provided on its outer periphery for locating the housing 26 at the axial center of the iron piping SP. The arms of the multi-axis arm 30 are provided at equal intervals around the circumference of the housing 26 and are configured to extend radially outward from the housing 26. Each arm of the multi-axis arm 30 is pantograph-shaped, and its joints have cylindrical supports 32 that support the housing 26 on the inner circumference of the iron piping SP.

[0030] For example, arm mechanism 28 can arbitrarily set the distance from mirror 18 to condenser lens 22. This allows condenser lens 22 to be brought close to the inner peripheral surface of iron pipe SP.

[0031] The other configurations are the same as those of the inspection devices 1A, 1B, 1C, and 1D according to the first to fourth embodiments.

[0032] [Operation of inspection device 1E] In the inspection device 1E according to the fifth embodiment, when inspecting an inspection target TG, each arm of the multi-axis arm 30 is extended radially outward from the housing 26 inside the iron pipe SP that serves as the inspection target TG, thereby positioning the housing 26 at the axial center of the iron pipe SP that serves as the inspection target TG. Then, the arm mechanism 28 is rotated relative to the housing 26 by an actuator such as a motor (not shown). This also rotates the mirror 18 and the condenser lens 22, allowing the inner wall surface of the iron pipe SP to become the inspection target.

[0033] Other operations, that is, operations up to the point where the reflected wave RW detected by the detector 16 is stored in the data logger 34, are the same as those of the inspection devices 1A, 1B, 1C, and 1D according to the first to fourth embodiments.

[0034] [Modification of Inspection Apparatus 1E] In the inspection device 1E according to the fifth embodiment, the multi-axis arm 30 is provided on the housing 26, but if wheels are provided on the housing 26 instead of the multi-axis arm 30, it becomes possible to move the iron pipe SP extending in the horizontal direction. Then, if the arm mechanism 28 is rotated while the inspection device 1E is moved in the horizontal direction, the tip of the arm mechanism 28 rotates in a spiral, and corrosion on the inner wall surface of the iron pipe SP can be efficiently inspected.

[0035] The present invention is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications. For example, if the inspection devices 1A, 1B, 1C, 1D, and 1E according to the first to fifth embodiments described above are mounted on a vehicle, a tunnel can be inspected as an inspection object TG. Furthermore, for example, if the inspection devices 1A, 1B, 1C, 1D, and 1E according to the above-mentioned embodiments 1 to 5 are mounted on an aerial vehicle such as a drone, they can inspect vertically extending objects such as chimneys as the inspection target object TG.

[0036] The contents described in each of the above embodiments can be understood, for example, as follows.

[0037] The inspection device (1A to 1E) according to the aspect of [1] is a light source (12) that outputs pulsed excitation light (LB) having a time width of 10 picoseconds to 10 nanoseconds; a nonlinear optical crystal (14) that generates terahertz waves (TH) by optical wavelength conversion of the excitation light (LB); a detector (16) for detecting a reflected wave (RW) of the terahertz wave (TH) reflected by an object to be inspected (TG); Equipped with.

[0038] According to this configuration, the terahertz waves (TH) generated by the nonlinear optical crystal (14) are more powerful (higher output) than the terahertz waves irradiated from the semiconductor element. Therefore, the optical components (24), such as the light source (12) and the nonlinear optical crystal (14), can be positioned farther away from the object under test (TG). Furthermore, because the terahertz waves (TH) generated by the nonlinear optical crystal (14) have a higher output than the terahertz waves irradiated from the semiconductor element, the terahertz waves (TH) generated by the nonlinear optical crystal (14) penetrate the difficult-to-transmit material that the terahertz waves irradiated from the semiconductor element do not easily penetrate. Meanwhile, because the light source (12) outputs pulsed excitation light (LB), continuous irradiation of the terahertz waves (TH) is avoided, which prevents the difficult-to-transmit material from burning. Therefore, the inspection devices (1A-1E) can inspect the object under test (TG) located below the difficult-to-transmit material.

[0039] [2] The inspection device (1B to 1E) according to another aspect is the inspection device according to [1], The apparatus includes a condenser lens (22) that condenses the terahertz waves (TH) and irradiates the terahertz waves (TH) onto the test object (TG).

[0040] According to this configuration, the terahertz waves (TH) generated in the nonlinear optical crystal (14) are focused by the focusing lens (22) and irradiated onto the test object (TG), so that the terahertz waves (TH) are collected on the test object (TG), and the reflected waves (RW) can be detected with high resolution by the detector (16).

[0041] [3] The inspection device (1C to 1E) according to another aspect is the inspection device according to [2], The device is provided with a mirror (18) that deflects the terahertz waves (TH) from the nonlinear optical crystal (14) at an angle in the range of 45° to 135° relative to the direction of propagation of the terahertz waves (TH), and the terahertz waves (TH) reflected by the mirror (18) are incident on the focusing lens (22).

[0042] With this configuration, the mirror (18) deflects the terahertz waves (TH) from the nonlinear optical crystal (14) at an angle ranging from 45° to 135° relative to the direction of propagation of the terahertz waves (TH). The terahertz waves (TH) reflected by the mirror (18) are then incident on the condenser lens (22), condensed, and irradiated onto the inspection target (TG). Therefore, by adjusting the mirror (18) so that the angle relative to the direction of propagation of the terahertz waves (TH) is within the range of 45° to 135°, it is possible to inspect the inspection target (TG) placed at any position between 45° and 135° relative to the direction of propagation of the terahertz waves (TH).

[0043] [4] The inspection device (1E) according to another aspect is the inspection device according to [3], a housing (26) that houses the light source (12), the nonlinear optical crystal (14), and the detector (16); an arm mechanism (28) that accommodates the mirror (18) and the condenser lens (22); Equipped with The arm mechanism (28) includes one end side where the mirror (18) is provided and the other end side where the focusing lens (22) is provided, and the arm mechanism (23) is attached to the housing (26) so that the one end side can rotate.

[0044] With this configuration, when the arm mechanism 28 rotates, one end where the mirror 18 is provided forms a circle, and the other end where the condenser lens 22 is provided forms a circle. This allows inspection of the inner wall surface of a cylinder (e.g., an iron pipe (SP)) that has the one end where the mirror 18 is provided as the center and the other end where the condenser lens 22 is provided as the outer periphery.

[0045] [5] The inspection device (1A-1E) according to another aspect is the inspection device according to any one of [1] to [4], a data logger (34) for storing data of the reflected wave (RW) detected by the detector (16); A trigger signal (TS) is transmitted to the data logger (34) simultaneously with the output of the excitation light (LB) from the light source (12), and the data logger (34) is configured to store data of the reflected wave (RW) upon receiving the trigger signal (TS).

[0046] According to this configuration, the data logger (34) stores the reflected wave (RW) data when it receives the trigger signal (TS), so the amount of reflected wave (RW) data stored in the data logger (34) can be reduced compared to when the data logger (34) continuously stores the reflected wave (RW) data.

[0047] [6] The inspection device (1E) according to another aspect is the inspection device according to any one of [1] to [5], The housing (26) is configured to be movable.

[0048] According to this configuration, the housing (26) moves, so that a long test object (TG) can be tested. [Explanation of symbols]

[0049] 1A~1E Inspection equipment 12 light source 14 Nonlinear optical crystals 16 detectors 18. Mirror 20 Half Mirror 22 Condenser lens 24 Optical Components 26 Case 28 Arm mechanism 30 Multi-axis arm 32 Support part 34 Data Logger 36 Terahertz Wave Fiber 38 Cylindrical Lens TG Inspection object SP Iron Piping RM resin material LB pulsed excitation light TH Terahertz waves RW reflected wave TS trigger signal

Claims

1. a light source that outputs pulsed excitation light having a time width of 10 picoseconds to 10 nanoseconds; a nonlinear optical crystal that generates terahertz waves by optical wavelength conversion of the pulsed excitation light; a detector that detects a reflected wave of the terahertz wave reflected by an object to be inspected; a condenser lens that condenses the terahertz waves and irradiates the terahertz waves onto the inspection object; a mirror that deflects the terahertz wave from the nonlinear optical crystal at an angle in the range of 45° to 135° with respect to the propagation direction of the terahertz wave; Equipped with The condenser lens is a cylindrical lens provided around the mirror, the mirror is provided rotatably, and the terahertz waves reflected by the mirror are incident on the condenser lens.

2. a housing that houses the light source, the nonlinear optical crystal, and the detector; an arm mechanism that houses the mirror and the condenser lens; Equipped with 2. The inspection device according to claim 1, wherein the arm mechanism includes one end where the mirror is provided and another end where the condenser lens is provided, and the one end of the arm mechanism is rotatably attached to the housing.

3. The inspection device according to claim 2 , wherein the housing is configured to be movable.

4. a data logger for storing data of the reflected wave detected by the detector; 4. The inspection device according to claim 1, wherein a trigger signal is transmitted to the data logger simultaneously with the output of the pulsed excitation light from the light source, and the data logger is configured to store data of the reflected wave upon receiving the trigger signal.

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