Measurement device and measurement method using terahertz waves

Abstract

To provide a terahertz wave measurement device and measurement method with which it is possible for a surveying personnel to visually confirm the position of a measurement object currently being measured.SOLUTION: A terahertz wave measurer 2 generates a terahertz wave with which to irradiate a measurement object 100 and outputs the generated terahertz wave, as well as detects the terahertz wave inputted after being reflected and captures an image of terahertz wave-irradiated surface 101 of the measurement object 100 by an RGB camera 3 on one hand. And, on the other hand, the terahertz wave measurer 2 matches the optical axis center of the terahertz wave of the terahertz wave measurer 2 with which to irradiate the measurement object 100 with the optical axis center of the RGB camera 3 by a beam splitter 9, and generates, by a computation processing unit 5, a display image from a terahertz wave detection signal and a measurement object imaging signal, in which a terahertz wave irradiation mark indicating a terahertz wave irradiation position relative to the measurement object 100 is located at center of the captured image of the RGB camera 3, with the generated display image displayed on the display unit 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a measurement device and a measurement method using terahertz waves. [Background technology]

[0002] Terahertz waves, which are electromagnetic waves with a frequency of approximately 0.1 THz to 10 THz, are highly permeable to materials such as plastic, paper, cloth, ceramics, and gypsum, and can therefore be used to visualize objects hidden by these materials by irradiating the objects with terahertz waves and detecting the transmitted or reflected waves. For example, internal structures that cannot be seen by the human eye, such as those inside the walls of buildings or behind the ceilings, can be visualized. In addition, the thickness of the materials through which visible light is difficult to transmit can be measured. Various configurations of measuring devices using this type of terahertz waves (hereinafter referred to as "terahertz wave measuring devices") have been known in the past.

[0003] For example, Patent Document 1 describes an inspection system that uses an electromagnetic wave source having an oscillation frequency of 10 GHz to 10 THz composed of a terahertz generator, combines multiple oscillation elements with different oscillation frequencies, or uses multiple detectors, irradiates the generated electromagnetic waves onto a structure and obtains transmitted or reflected images, thereby enabling imaging of defect distribution on the surface and inside of a structure.

[0004] For example, Patent Document 2 describes a real-time non-contact non-destructive thickness measurement device using terahertz waves that can measure the thickness of a sample. This measurement device inputs a fixed wavelength laser and a swept wavelength laser into a coupler, inputs the mixed light formed into a generator that generates terahertz waves, inputs the terahertz waves emitted from the generator and transmitted through or reflected by the sample into a detector, and the detector biases the photocarriers excited by the mixed light with the electric field of the terahertz waves to generate a photocurrent, and a data acquisition unit acquires the photocurrent in the form of digital data, outputs it to a calculation unit to convert it into frequency domain data, performs a fast Fourier transform on the frequency domain data to generate time domain data, and calculates the thickness of the sample based on the time domain data. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2007-132915 [Patent Document 2] Patent Publication No. 2017-15681 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in these conventional inspection systems or measurement devices, the terahertz waves irradiated from the generator cannot be seen, so the person measuring cannot recognize which position on the measurement object is being irradiated with the terahertz waves, i.e., the person measuring cannot visually recognize which position on the measurement object is being inspected or measured. This problem is particularly noticeable when inspecting or measuring a wide area.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a terahertz wave measurement device and a terahertz wave measurement method that allow a measurer to visually confirm in real time the position at which he or she is currently measuring an object to be measured. [Means for solving the problem]

[0008] In order to achieve the above object, a first aspect of the terahertz wave measurement device according to the present invention comprises a terahertz wave measurement instrument, a camera such as an RGB camera, a beam splitter, an arithmetic processing unit, and a display unit in one case, the terahertz wave measurement instrument generates and outputs terahertz waves to be irradiated toward a measurement object that is opaque to visible light, and detects terahertz waves reflected by the measurement object and an internal structure and input thereto, the camera photographs the surface of the measurement object irradiated with terahertz waves, the beam splitter photographs the terahertz wave irradiated surface of the measurement object, and the terahertz wave measurement instrument detects the terahertz wave reflected by the measurement object and an internal structure. The arithmetic processing unit is arranged so that the center of the optical axis through which the terahertz waves of the terahertz wave measuring instrument are irradiated onto the object to be measured coincides with the center of the optical axis of the camera, and the arithmetic processing unit receives a terahertz wave detection signal from the terahertz wave measuring instrument and a measurement object imaging signal from the camera, and generates a display image from the two synchronized signals in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position (which is also the reflection position) on the surface of the object to be measured is located at the center of the image captured by the camera, and the display unit displays the display image generated by the arithmetic processing unit.

[0009] In order to achieve the above object as well, a second aspect of the terahertz wave measurement device according to the present invention comprises a terahertz wave measurement instrument, a camera such as an RGB camera, an arithmetic processing unit, a storage unit, and a display unit, all in one case, the terahertz wave measurement instrument generates and outputs terahertz waves to be irradiated toward a measurement object that is opaque to visible light, and detects terahertz waves reflected by the measurement object and an internal structure and input thereto, the camera photographs the surface of the measurement object to which the terahertz waves are irradiated, measures its internal parameters in advance, and stores this measurement data in the storage unit, the arithmetic processing unit detects the terahertz waves reflected by the measurement object and an internal structure, the camera photographs the surface of the measurement object to which the terahertz waves are irradiated, measures its internal parameters in advance, and stores this measurement data in the storage unit, and the arithmetic processing unit detects the terahertz waves reflected by the measurement object and an internal structure and stores the measurement data in the storage unit. The arithmetic processing unit receives a terahertz wave detection signal from the terahertz wave measuring instrument and a measurement object imaging signal from the camera, and generates a display image from the two synchronized signals, in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position on the surface of the measurement object is displayed on the image captured by the camera.This display image is generated by converting the coordinates of the center position of the optical axis at which the terahertz waves output from the terahertz wave measuring instrument are irradiated onto the measurement object and the coordinates of the center position of the optical axis of the camera into the same coordinate system, for example the world coordinate system, and the display unit displays the display image generated by the arithmetic processing unit.

[0010] In order to convert the coordinates of the optical axis center position where the terahertz waves of the terahertz wave measuring instrument are irradiated onto the measurement object and the coordinates of the optical axis center position of the camera into the same coordinate system, for example, a world coordinate system, in the calculation processing unit, this can be done by using a translation (parallel movement) matrix and a rotation matrix based on, for example, the offset value of each optical axis center position, the angle offset value of each optical axis center position, the distance value to the terahertz wave reflecting surface measured by the terahertz wave measuring instrument, and the internal parameters.

[0011] In the first and second aspects, the synchronization of the terahertz wave detection signal from the terahertz wave measuring instrument and the measurement object image signal from the camera is preferably performed by a synchronization signal generating unit such as an oscillator circuit that transmits a synchronization signal such as a shutter trigger to the terahertz wave measuring instrument and the camera provided in the case. Also, the synchronization of the terahertz wave detection signal and the measurement object image signal may be preferably configured so that the terahertz wave detection signal and the measurement object image signal inputted at the same time are synchronized in the arithmetic processing unit.

[0012] Furthermore, the storage unit in the second embodiment may also be a storage unit provided inside the arithmetic processing unit.

[0013] In order to achieve the above object, a terahertz wave measurement method according to the present invention is a measurement method using a terahertz wave measurement device including a terahertz wave measuring instrument, a camera such as an RGB camera, a beam splitter, an arithmetic processing unit, and a display unit in a single case, the terahertz wave measuring instrument generates and outputs terahertz waves to be irradiated toward a measurement object that is opaque to visible light, and detects terahertz waves reflected and input by the measurement object and an internal structure, and the camera photographs the surface of the measurement object irradiated with the terahertz waves, The beam splitter aligns the center of the optical axis through which the terahertz waves output from the terahertz wave measuring instrument are irradiated onto the object to be measured with the center of the optical axis of the camera, and the arithmetic processing unit generates a display image in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position (which is also the reflection position) on the surface of the object to be measured is located at the center of the image captured by the camera from the two signals, which are synchronized between the terahertz wave detection signal input from the terahertz wave measuring instrument and the measurement object imaging signal input from the camera, and displays this display image on the display unit.

[0014] Also, in order to achieve the above object, a terahertz wave measurement method according to the present invention is a measurement method using a terahertz wave measurement device equipped with a terahertz wave measurement instrument, a camera such as an RGB camera, an arithmetic processing unit, a storage unit, and a display unit in one case, in which the terahertz wave measurement instrument generates and outputs terahertz waves to be irradiated toward a measurement object that is opaque to visible light, and detects terahertz waves reflected by the measurement object and an internal structure and input thereto, and the camera photographs the surface of the measurement object irradiated with the terahertz waves, measures its internal parameters in advance, and stores this measurement data in a storage medium. The data is stored in the memory unit, and the arithmetic processing unit generates a display image on the display unit from the two signals, which are synchronized between the terahertz wave detection signal input from the terahertz wave measuring instrument and the measurement object imaging signal input from the camera, in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position on the surface of the measurement object is displayed on the image captured by the camera.This display image is generated by converting the coordinates of the center position of the optical axis at which the terahertz waves output from the terahertz wave measuring instrument are irradiated onto the measurement object and the coordinates of the center position of the optical axis of the camera into the same coordinate system, for example a world coordinate system. Effect of the Invention

[0015] According to the present invention, the terahertz wave measuring device is placed in a single case, and the irradiation position of the invisible terahertz wave on the surface of the object to be measured can be visually confirmed in real time, so that the person measuring can move freely while measuring and confirming the measurement position of the object to be measured. [Brief description of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a first embodiment of a terahertz wave measuring device according to the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a front view showing a display state of the display unit; [Figure 4] FIG. 2 is a block diagram showing a second embodiment of a terahertz wave measuring device according to the present invention. [Diagram 5] FIG. 4 is a front view showing a display state of the display unit; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A first embodiment of a terahertz wave measuring device of the present invention will be described below with reference to the accompanying drawings, FIGS. As shown in Fig. 1, the terahertz wave measurement device 1 includes a terahertz wave measuring instrument 2, an RGB camera 3, a synchronization signal generating unit 4, an arithmetic processing unit 5, a display unit 6, an operation unit 7, a memory unit 8, and a beam splitter 9, all of which are housed in a single case 10 (see Fig. 2). As shown in Fig. 2, the case 10 is of a size and weight that allows a measurer M to carry it in his or her hand while moving around to perform measurement operations.

[0018] 1, the terahertz wave measuring instrument 2 has a terahertz wave generator 21 that generates and outputs terahertz waves with a frequency of 0.1 THz to 10 THz, preferably 75 GHz to 110 GHz or 20 GHz to 30 GHz to be irradiated onto a wall surface 101 in order to detect an internal structure behind an opaque wall 100 of an architectural structure, which is an object to be measured, and a terahertz wave detector 22 that detects the input terahertz waves reflected by the wall surface 101 and an internal structure 102 behind the wall 100. An RGB camera 3 is for photographing the wall surface 101 onto which the terahertz waves are irradiated.

[0019] The optical axis center P of the terahertz wave measuring instrument 2, which irradiates the wall surface 101 with the terahertz waves, and the optical axis center Q of the RGB camera 3 are configured to coincide with each other by a beam splitter 9. The beam splitter 9 is made of, for example, a glass plate on which an ITO (indium tin oxide) coating is formed, and transmits visible light but reflects terahertz waves. By aligning the optical axis center P of the terahertz wave measuring instrument 2, which irradiates the wall surface 101 with the terahertz waves, and the optical axis center Q of the RGB camera 3, the irradiation position (which is also the reflection position) of the terahertz waves on the wall surface 101 corresponds to the center position of the image captured by the RGB camera 3.

[0020] The terahertz wave detection signal sent from the terahertz wave detector 22 and the measurement object image signal from the RGB camera 3 are input in synchronization with a synchronization signal from a synchronization signal generating unit 4 to the calculation processing unit 5, and based on the two synchronized signals, a display image 60 is generated in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position on the wall surface 101 of the wall 100 is located at the center of the image captured by the RGB camera 3. That is, as shown in Fig. 3, a small circle 61 is displayed as a terahertz wave irradiation mark at the center of the image captured by the RGB camera 3, and the display image 60 in which this small circle 61 is displayed is displayed on the display unit 6. This display unit 6 is composed of a liquid crystal display or the like.

[0021] The operation unit 7 allows the operator M (see FIG. 2) to perform various operations on the terahertz wave measuring device 1, and includes, for example, a power key, numeric keys, an execution key, etc. The storage unit 8 is made up of a ROM in which the arithmetic program of the arithmetic processing unit 5 is stored, and a RAM in which image data is temporarily stored.

[0022] In this embodiment, as shown in FIG. 2, the measurer M holds the above-mentioned terahertz wave measuring device 1 in his / her hand and moves back and forth parallel to the wall surface 101 while irradiating the wall surface 101 with terahertz waves from the upper part to the lower part in a zigzag pattern, thereby detecting the internal structure 102 behind the wall 100. At this time, as shown in FIG. 1, the optical axis center P of the terahertz wave measuring device 2 irradiating the wall surface 101 with terahertz waves and the optical axis center Q of the RGB camera 3 are configured to coincide with each other by the beam splitter 9, so that, as shown in FIG. 3, a small circle 61 indicating the terahertz wave irradiation position is displayed at the center of the captured image of the RGB camera 3. Therefore, the measurer M can visually confirm the irradiation position of the terahertz wave in real time by visually checking the small circle 61 displayed on the display unit 6. Then, the measurer M can reliably irradiate the terahertz wave to the wall surface 101 corresponding to the position where the internal structure 102 behind the wall 100 is to be detected by setting the small circle 61 as a target.

[0023] As shown in FIG. 1, the terahertz waves irradiated to the wall surface 101 are reflected at a reflectance corresponding to the material of the wall surface 101 and penetrate the inside of the wall 100. When the terahertz waves hit the internal structure 102, they are reflected at a reflectance corresponding to the material of the internal structure 102. If the internal structure 102 is made of metal, they are reflected at a high reflectance. The reflected terahertz waves are input to the terahertz wave detector 22 by the beam splitter 9, converted into detection data, and sent to the calculation processing unit 5, where the distance to the wall surface 101 and its material are specified, and the distance to the internal structure 102 and its material are specified. These distances and materials are usually specified in a post-processing stage. In FIG. 1, the irradiated wave of the terahertz wave is shown by a solid line, and the reflected wave is shown by a broken line. The irradiated wave and the reflected wave are shown at different positions for convenience of illustration. Even if there are multiple internal structures 102, they can be detected in the same manner as described above.

[0024] Next, a second embodiment of the terahertz wave measuring device of the present invention will be described with reference to FIGS. As shown in Fig. 4, the terahertz wave measurement device 11 includes a terahertz wave measuring instrument 12, an RGB camera 13, a synchronization signal generating unit 14, an arithmetic processing unit 15, a display unit 16, an operation unit 17, and a storage unit 18, all of which are provided in one case (see case 10 in Fig. 2). As in the first embodiment described above, the case is of a size and weight that allows a measurer M to carry out measurement work while moving around by hand.

[0025] The terahertz wave measuring instrument 12 has a configuration similar to that of the first embodiment described above, and includes a terahertz generator 121 that generates and outputs terahertz waves to be irradiated onto a measurement object such as a wall 100 of an architectural structure, and a terahertz wave detector 122 that detects the terahertz waves reflected and input by the wall 100 and internal structure 102.

[0026] RGB camera 13 photographs the surface of the object to be measured that is irradiated with terahertz waves, i.e., wall surface 101, and its internal parameters are measured in advance and the measured data is stored in storage unit 18. The internal parameters, specifically, relate to the characteristics of the camera lens, such as the focal length, principal point (center of image), and distortion parameters, and are acquired by photographing a target such as a circle grid with RGB camera 13 and performing calibration.

[0027] The arithmetic processing unit 15 receives the terahertz wave detection signal from the terahertz wave detector 122 and the measurement target image signal from the RGB camera 13 in synchronization with the synchronization signal from the synchronization signal generating unit 14, and generates a display image to be displayed on the display unit 16 from the two synchronized signals. In this embodiment, unlike the first embodiment, the optical axis center P1 for irradiating the wall 100 with terahertz waves from the terahertz wave generator 121 and the optical axis center Q1 of the RGB camera 13 do not coincide with each other but are shifted from each other. The arithmetic processing unit 15 converts, for example, the coordinates of the optical axis center position of the terahertz wave generator 121 on the wall surface 101 and the coordinates of the optical axis center position of the RGB camera 13 into the same coordinate system, for example, the world coordinate system, and generates a display image 160 in which a small circle 161, which is a terahertz wave irradiation mark indicating the terahertz wave irradiation position (which is also the reflection position) on the surface 101 of the wall 100, is displayed on the image captured by the RGB camera 13 (see FIG. 5).

[0028] The coordinate system conversion in the calculation processing unit 15 is performed using a translation (parallel movement) matrix and a rotation matrix based on, for example, the optical axis center position at which the terahertz waves of the terahertz wave measuring instrument 12 are irradiated onto the wall surface 101, the offset value of the optical axis center position of the RGB camera 13, the angle offset value of each optical axis center position, the distance value to the terahertz wave reflecting surface measured by the terahertz wave measuring instrument 12, and the internal parameters.

[0029] In this way, a display image 160, which is generated by integrating the coordinate systems and in which the irradiation position of the terahertz wave is displayed by a small circle 161 superimposed on the image captured by the RGB camera 13, is displayed on the display unit 16. Note that in this embodiment, the display position of the small circle 161 does not necessarily coincide with the center of the image captured by the RGB camera 13.

[0030] In this embodiment, as in the first embodiment, an operator M (see FIG. 2) holds the above-mentioned terahertz wave measurement device 11 in his / her hand and irradiates terahertz waves toward wall surface 101 while moving back and forth parallel to the wall surface 101, thereby detecting an internal structure 102 behind the wall 100. At this time, the position of a small circle 161 displayed on display unit 16 is the irradiation position of the terahertz waves, and operator M can visually confirm the irradiation position of the terahertz waves in real time by visually checking the small circle 161. Therefore, operator M can reliably irradiate the terahertz waves to the wall surface 101 corresponding to the position where he / she wants to detect an internal structure 102 behind the wall 100.

[0031] The present invention is not limited to the above-mentioned embodiments. For example, the camera is not limited to the RGB camera 3, 13, and if a LiDAR is provided in addition to the camera, more accurate image data can be obtained and the distance to the object can be measured. The terahertz wave measuring device 1, 11 can be held by the measurer M, or if it is larger and heavier, it can be mounted on a dolly or the like and the measurer M can measure while moving the dolly. Furthermore, the terahertz wave irradiation mark is not limited to the small circle 61, 161, and a mark of an appropriate shape can be selected. Furthermore, the above-mentioned embodiments can be modified based on the knowledge of a person skilled in the art, and it goes without saying that such a form is also included in the scope of the present invention. [Explanation of symbols]

[0032] 1,11 Terahertz wave measurement device 2,12 Terahertz wave measuring instrument 3,13 RGB camera 4,14 Synchronization signal generator 5,15 Processing unit 6,16 Display section 7,17 Control unit 8,18 Storage part 9 Beam splitter 21, 121 Terahertz wave generator 22,122 Terahertz wave detector 60,160 Display images 61,161 small yen 100 Wall 101 Wall surface 102 Internal structure P,P1 Terahertz wave irradiation optical axis center Q,Q1 RGB camera optical axis center

Claims

1. A terahertz wave measuring instrument, a camera, a beam splitter, a calculation processing unit, and a display unit are all housed in one case. the terahertz wave measuring instrument generates and outputs a terahertz wave to be irradiated toward a measurement object, and detects a reflected and input terahertz wave; The camera photographs a surface of the object to be measured that is irradiated with terahertz waves, the beam splitter is disposed so that a center of an optical axis along which the terahertz wave output from the terahertz wave measuring instrument is irradiated onto the measurement object coincides with a center of an optical axis of the camera; the arithmetic processing unit receives a terahertz wave detection signal from the terahertz wave measuring instrument and a measurement object photographing signal from the camera, and generates a display image in which a terahertz wave irradiation mark indicating a terahertz wave irradiation position on the surface of the measurement object is positioned at the center of the photographed image of the camera from the two synchronized signals, The display unit displays a display image generated by the arithmetic processing unit. A measuring device using terahertz waves.

2. A terahertz wave measuring device, a camera, a calculation processing unit, a storage unit, and a display unit are included in one case. the terahertz wave measuring instrument generates and outputs a terahertz wave to be irradiated toward a measurement object, and detects a reflected and input terahertz wave; the camera captures an image of the surface of the measurement object irradiated with the terahertz wave, measures its internal parameters in advance, and stores the measurement data in the storage unit; the arithmetic processing unit receives a terahertz wave detection signal from the terahertz wave measuring instrument and a measurement object photographing signal from the camera, and generates a display image based on the two synchronized signals, in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position on the measurement object surface is displayed on the image captured by the camera, and this display image is generated by converting the coordinates of the optical axis center position at which the measurement object is irradiated with the terahertz waves output from the terahertz wave measuring instrument and the coordinates of the optical axis center position of the camera into the same coordinate system; The display unit displays a display image generated by the arithmetic processing unit. A measuring device using terahertz waves.

3. The synchronization of the terahertz wave detection signal from the terahertz wave measuring device and the measurement object image signal from the camera is performed by a synchronization signal generating unit that transmits a synchronization signal to the terahertz wave measuring device and the camera provided in the case.

3. A measuring device using terahertz waves according to claim 1 or 2.

4. The terahertz wave detection signal from the terahertz wave measuring instrument and the measurement object image signal from the camera are synchronized in the arithmetic processing unit with respect to the terahertz wave detection signal and the measurement object image signal input at the same time.

3. A measuring device using terahertz waves according to claim 1 or 2.

5. A measurement method using a terahertz wave measurement device including a terahertz wave measuring instrument, a camera, a beam splitter, a calculation processing unit, and a display unit in one case, comprising: The terahertz wave measuring device generates and outputs a terahertz wave to be irradiated toward a measurement object, and detects the reflected and input terahertz wave; The camera captures an image of the surface of the measurement object irradiated with the terahertz wave; The beam splitter aligns the center of an optical axis of the camera along which the terahertz wave output from the terahertz wave measuring instrument is irradiated onto a measurement object, and The arithmetic processing unit generates a display image in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position on the surface of the measurement object is positioned at the center of the image captured by the camera from both the terahertz wave detection signal input from the terahertz wave measuring instrument and the measurement object photographing signal input from the camera, which are synchronized with each other, and displays the display image on the display unit. A measurement method using terahertz waves.

6. A measurement method using a terahertz wave measurement device including a terahertz wave measuring instrument, a camera such as an RGB camera, a calculation processing unit, a storage unit, and a display unit in one case, comprising: The terahertz wave measuring device generates and outputs a terahertz wave to be irradiated toward a measurement object, and detects the reflected and input terahertz wave; The camera captures an image of the surface of the measurement object irradiated with the terahertz wave, measures its internal parameters in advance, and stores the measurement data in the storage unit; The arithmetic processing unit generates a display image in which a terahertz wave irradiation mark indicating the terahertz wave irradiation position on the surface of the object to be measured is displayed on the image captured by the camera from the terahertz wave detection signal input from the terahertz wave measuring instrument and the measurement object photographing signal input from the camera, which are synchronized with each other, and displays the display image on a display unit. The display image is generated by converting the coordinates of the optical axis center position at which the measurement object is irradiated with the terahertz waves output from the terahertz wave measuring instrument and the coordinates of the optical axis center position of the camera into the same coordinate system. A measurement method using terahertz waves.

Images