WO2020045444A1

WO2020045444A1 - Method and apparatus for inspection using terahertz wave

Info

Publication number: WO2020045444A1
Application number: PCT/JP2019/033540
Authority: WO
Inventors: 南出　泰亜; 耕二縄田; 佑馬瀧田
Original assignee: 国立研究開発法人理化学研究所
Priority date: 2018-08-31
Filing date: 2019-08-27
Publication date: 2020-03-05
Also published as: JP2020034530A; JP7232498B2

Abstract

An inspection apparatus 100 which uses a terahertz wave is provided with a terahertz-wave generating device 10 for generating a terahertz wave, an interaction unit 20 having an action space 7 into which a terahertz wave is introduced and in which an inspection object is placed, and a terahertz wave detection device 30 for generating detection data on the basis of a terahertz wave which interacts with the inspection object in the action space 7 and passes through the action space 7. The interaction unit 20 has a reflecting surface 8 for reflecting the terahertz wave in the action space 7. The terahertz wave is reflected by the reflecting surface 8, and thereby passes through the action space 7 multiple times, and is incident on the terahertz wave detection device 30 positioned outside the action space 7.

Description

Inspection apparatus and inspection method using terahertz wave

The present invention relates to an apparatus and a method for inspecting an inspection object using terahertz waves.

Terahertz waves are electromagnetic waves having a frequency of about 1 terahertz (10 ¹² Hz). Terahertz waves have the property of transmitting various substances. Terahertz waves are generated by making excitation light incident on a nonlinear optical crystal. An apparatus for inspecting a substance using terahertz waves is described in, for example, Patent Document 1.

In Patent Document 1, the generated terahertz wave is incident on the measurement sample, and the spectrum of the terahertz wave absorbed by the measurement sample is obtained based on the terahertz wave transmitted through the measurement sample.

JP 2011-75583 A

Using a terahertz wave, it is possible to inspect whether or not an inspection target (for example, gas, solid, or the like) contains a target component. That is, a terahertz wave is introduced into a test object, a spectrum of the terahertz wave absorbed by the test object is obtained, and the presence or absence of the target component can be inspected based on the spectrum. In this case, it is desired to increase the detection accuracy of the target component.

Further, when inspecting whether or not a gas to be inspected (hereinafter also referred to as an inspection target gas) contains a target component, even if the terahertz wave is not propagated to the spatial region to be inspected, It is desired to be able to inspect Terahertz waves with terahertz waves. For example, the terahertz wave is used to check whether or not the target component exists in the gas in the space area without propagating the terahertz wave to a space area through which a person passes (a ticket gate at a station, a security gate at an airport or a building, etc.). It is desired. In that case, it is desired that the inspection and discrimination of the target component be performed at a high speed so as not to hinder traffic and the like.

In addition, a device for inspecting a test object (gas, solid, or the like) using a terahertz wave is not only a terahertz wave generator that generates a terahertz wave, but also a terahertz for detecting a terahertz wave after interacting with the test object. A wave detection device is provided. The terahertz wave generator includes an excitation light source, a nonlinear optical crystal that generates a terahertz wave by excitation light from the excitation light source, and the like. The terahertz wave detection device includes a non-linear optical crystal that generates a signal light by the terahertz wave and the excitation light after interacting with the inspection target, a detector that detects the signal light, and the like. As described above, since the device for inspecting the inspection object using the terahertz wave includes the terahertz wave generator and the terahertz wave detector each including a plurality of components, the total number of components increases. Therefore, it is desired to make the configuration of the device for inspecting the terahertz wave more compact.

Therefore, a first object of the present invention is to increase the detection sensitivity of a target component included in a test object.
A second object of the present invention is to enable high-speed inspection of gas in a space region to be inspected by the terahertz wave without transmitting the terahertz wave to the space region to be inspected.
A third object of the present invention is to make the configuration of an inspection apparatus using terahertz waves more compact.

In order to achieve the above-described first object, an inspection apparatus using a terahertz wave according to the first aspect of the present invention includes:
A terahertz wave generator for generating a terahertz wave,
An interaction unit having an operation space in which the terahertz wave is introduced and an inspection target is present;
A terahertz wave detection device that generates detection data based on the terahertz wave that has interacted with the test object in the working space (transmitted, reflected, scattered) and passed through the working space, and outputs the detected data,
The interaction unit has a reflecting surface that reflects the terahertz wave in the working space, and the terahertz wave passes through the working space a plurality of times by being reflected by the reflecting surface, and The light is incident on the terahertz wave detection device located outside the space.

In order to achieve the first object described above, in the inspection method using terahertz waves according to the first aspect of the present invention,
(A) generating a terahertz wave,
(B) introducing the terahertz wave into the working space where the test object is present, and causing the terahertz wave to interact with the test object in the working space;
(C) generating detection data based on the terahertz wave from the working space, outputting the detection data,
In (B), the terahertz wave passes through the working space a plurality of times by being reflected by a reflecting surface in the working space.

In order to achieve the above-mentioned second object, an inspection apparatus using a terahertz wave according to the second aspect of the present invention comprises:
A terahertz wave generator for generating a terahertz wave,
The terahertz wave and the gas to be tested are introduced, and an interaction unit having an action space for allowing the two to interact with each other,
A terahertz wave detection device that generates detection data based on the terahertz wave that has passed through the working space and outputs the detection data,
The interaction unit includes a space forming body that forms the working space,
The working space has an inlet communicating with the outside, and an external gas can flow into the working space as the test gas through the inlet.

In order to achieve the second object described above, the inspection method using terahertz waves according to the second aspect of the present invention,
(A) generating a terahertz wave,
(B) introducing the terahertz wave into the working space where the gas to be tested is present, and allowing the terahertz wave to interact with the gas to be tested in the working space;
(C) generating detection data based on the terahertz wave from the working space, outputting the detection data,
The working space has an inlet communicating with the outside, and an external gas flows into the working space through the inlet as a gas to be inspected.

In order to achieve the above-described third object, an inspection apparatus using a terahertz wave according to a third aspect of the present invention includes:
A terahertz wave generator that generates a terahertz wave and introduces the terahertz wave into an inspection target area;
A terahertz wave detection device that outputs detection data based on the terahertz wave that has passed through the inspection target area,
The terahertz wave generator includes an excitation light source that generates excitation light, and a nonlinear optical crystal that generates a terahertz wave when the excitation light is incident so as to satisfy an angle phase matching condition for generation.
The terahertz wave detection device, the non-linear optical crystal that generates signal light from the terahertz wave and the excitation light by being incident so that the terahertz wave from the inspection target area satisfies the angular phase matching condition for detection A detector that outputs detection data based on the signal light,
The nonlinear optical crystal is shared by the terahertz wave generator and the terahertz wave detector.

In order to achieve the third object described above, in the inspection method using terahertz waves according to the third aspect of the present invention,
(A) generating a terahertz wave,
(B) introducing the terahertz wave into a region to be inspected,
(C) generating detection data based on the terahertz wave passed through the inspection target area, outputting the detection data,
In the above (A), the terahertz wave is generated by the excitation light being incident on the nonlinear optical crystal so as to satisfy the angle phase matching condition for generation,
In (C), the terahertz wave from the inspection target region is incident on the nonlinear optical crystal so as to satisfy the angle phase matching condition for detection, so that signal light is generated from the terahertz wave and the excitation light. Generating the detection data based on the signal light;
The non-linear optical crystal is shared between (A) and (C).

According to the first aspect of the present invention, the terahertz wave introduced into the working space passes through the working space a plurality of times by being reflected by the reflection surface, so that the terahertz wave transmits through the working object a plurality of times in the working space. Or it can be reflected or scattered by the test object. As described above, the presence or absence of the target component included in the inspection target can be inspected based on the terahertz wave that has interacted more with the inspection target (such as a gas or a solid). Therefore, the detection sensitivity of the target component is increased.

According to the second aspect of the present invention, an external gas can flow into the working space through the inlet as the gas to be inspected. Therefore, even if the terahertz wave is not propagated to the space region to be inspected, the gas in the space region can be inspected by the terahertz wave by flowing the gas in the external space region into the working space through the inlet as the gas to be inspected. . Further, in the inspection using terahertz waves, the gas can be inspected at high speed because the gas need not be pre-processed.

According to the second aspect of the present invention, the non-linear optical crystal is used for both the generation of the terahertz wave to be introduced into the inspection target region and the generation of the signal light by the terahertz wave passing through the inspection target region. Therefore, since it is not necessary to provide a nonlinear optical crystal for each of the generation of the terahertz wave and the generation of the signal light, the configuration of the inspection apparatus using the terahertz wave can be made more compact.

1 shows a configuration of an inspection device according to a first embodiment of the present invention. 3 shows a relationship between wave number vectors according to the first embodiment. FIG. 3 is a sectional view taken along line III-III of FIG. 1. It is explanatory drawing of the effect | action of the inner peripheral surface in an action space. 3 shows the spectral characteristics of a terahertz wave. 5 shows a configuration of an inspection device according to a second embodiment of the present invention. 9 shows a relationship between wave number vectors in the second embodiment. The configuration when a resonator is provided is shown. 7 shows a configuration of an inspection device according to a modification. FIG. 10 is a view taken in the direction of arrows XX in FIG. 9.

A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same reference numerals are given to the common parts in the respective drawings, and the duplicate description will be omitted.

[First Embodiment]
FIG. 1 shows a configuration of an inspection apparatus 100 according to a first embodiment of the present invention. The inspection apparatus 100 is an apparatus for inspecting an inspection target gas using the terahertz wave Lt. That is, the inspection apparatus 100 is an apparatus that generates a terahertz wave Lt, introduces the terahertz wave Lt into the inspection target gas, and generates and outputs detection data based on the terahertz wave Lt that has passed through the inspection target gas. This detection data includes information on the components of the gas to be inspected. Therefore, the components of the gas to be inspected can be detected based on the detection data.

As shown in FIG. 1, the inspection device 100 includes a terahertz wave generation device 10, an interaction unit 20, and a terahertz wave detection device 30.

(Configuration of terahertz wave generator)
The terahertz wave generator 10 generates a terahertz wave Lt, and introduces the terahertz wave Lt into a later-described working space 7 of the interaction unit 20. In the present embodiment, the terahertz wave generator 10 includes an excitation light source 1, a nonlinear optical crystal 3, and an introduction optical system 5.
Is provided.

The excitation light source 1 generates the excitation light Lp and causes the excitation light Lp to enter the nonlinear optical crystal 3. The excitation light Lp is also called pump light. For example, the excitation light source 1 generates near-infrared light as the excitation light Lp. Pumping light Lp excitation light source 1 is produced, which may have a spectral peak occurs at a predetermined wavelength (corresponding to the angular frequency omega _p1 below), for example, it may have a single wavelength. Further, the excitation light Lp may be pulsed light. The time width of this pulsed light may be on the order of sub-nanoseconds (for example, a value of 1 × 10 ⁻¹⁰ seconds or more and less than 1 × 10 ⁻⁹ seconds). The excitation light source 1 may be, for example, a Q-switched Nd: YAG laser, but is not limited to this.

The nonlinear optical crystal 3 generates the terahertz wave Lt and the idler light Li when the excitation light Lp is incident from the excitation light source 1 so as to satisfy an angle phase matching condition for generation described below. The angle phase matching condition for generation includes the following energy conservation law and momentum conservation law.
Energy conservation law: ω _p1 = ω _i1 + ω _T1
Law of conservation of momentum: k _p1 = _{ki 1} + k _T1
Here, ω _p1 is the angular frequency of the pump light Lp, ω _i1 is the angular frequency of the idler light Li, and ω _T1 is the angular frequency of the terahertz wave Lt. Further, k _p1 is a wave vector of the excitation light Lp, ki ₁ is a wave vector of the idler light Li, and k _T1 is a wave vector of the terahertz wave Lt.

FIG. 2 shows a part of FIG. FIG. 2 shows the relationship between wave number vectors k _p1 , k _i1 , and k _T1 . In the example of FIG. 2, the wave vector k _i1 of the idler light Li is a wave vector of the idler light Li before being reflected, assuming that the idler light Li is reflected at the reflection position Pr.

In one example, as shown in FIG. 1, the excitation light Lp from the excitation light source 1 is incident on the side surface 3a of the nonlinear optical crystal 3 and totally reflected at the reflection position Pr on the end surface 3b. As a result, the terahertz wave Lt and the idler light Li are generated according to the angle phase matching condition for generation.

The nonlinear optical crystal 3 may be, for example, a LiNbO ₃ crystal. In the example of FIG. 1, the nonlinear optical crystal 3 has a trapezoidal shape when viewed from a direction perpendicular to the plane of the drawing. In this case, in FIG. 1, each surface of the nonlinear optical crystal 3 that intersects with the plane of FIG. 1 may be a plane orthogonal to the plane of FIG.

In the first embodiment, the wavelength of the idler light Li has a certain width because a seed light or a resonator described later is not used. Since the traveling direction of the idler light Li complies with the angular phase matching condition for generation for each wavelength, the idler light Li has a certain spread as shown in FIG. Further, according to each wavelength of the idler light Li, the wavelength of the terahertz wave Lt has a certain width according to the angle phase matching condition for generation. Since the direction in which the terahertz wave Lt is emitted from the end face 3b is in accordance with the angle phase matching condition for generation for each wavelength, the terahertz wave Lt has a certain extent as shown in FIG. The terahertz wave component having the center wavelength in the wavelength width of the terahertz wave Lt may be emitted from the end face 3b in a direction substantially orthogonal to the end face 3b.

The introduction optical system 5 introduces the terahertz wave Lt emitted from the nonlinear optical crystal 3 into the working space 7. In the example of FIG. 1, the introduction optical system 5 includes a reflection mirror 5a and a lens 5b. The reflection mirror 5 a reflects the terahertz wave Lt from the nonlinear optical crystal 3 so as to guide it to the working space 7. The lens 5b adjusts the degree of convergence (spread) of the terahertz wave Lt. The lens 5b may be a condenser lens.

(Configuration of interaction unit)
The interaction unit 20 will be described with reference to FIGS. FIG. 3 is a sectional view taken along the line III-III of FIG.

The interaction unit 20 has the working space 7 into which the terahertz wave Lt and the gas to be tested are introduced. In the working space 7, the terahertz wave Lt and the gas to be inspected interact. In the present embodiment, the interaction unit 20 has the reflecting surface 8 that reflects the terahertz wave Lt in the working space 7. The terahertz wave Lt introduced into the working space 7 is reflected by the reflecting surface 8 so as to pass through the working space 7 a plurality of times and enter the terahertz wave detecting device 30 located outside the working space 7. It has become. The reflection surface 8 (an inner peripheral surface 8 described later) is formed of a material (for example, metal) that reflects a terahertz wave.

In the present embodiment, the interaction unit 20 includes the space forming body 9, the introduction path forming body 11, the discharge path forming body 13, the gas flow generating device 15, and the rectifying section 16.

The space forming body 9 forms the working space 7 inside. Further, the space forming body 9 has an introduction portion 9a into which the terahertz wave Lt is introduced. The introduction portion 9a is formed of a material through which the terahertz wave Lt passes. The working space 7 has an inlet 7a and an outlet 7b communicating with the outside. External gas can flow into the working space 7 through the inlet 7a as a gas to be inspected. Further, the gas in the working space 7 can flow out to the outside through the outlet 7b. The inlet 7a and the outlet 7b are located, for example, so as to sandwich a region through which the terahertz wave Lt passes in the working space 7. The working space 7 may be sealed to the outside except for the inlet 7a and the outlet 7b.

The space forming body 9 has an inner peripheral surface as the above-mentioned reflecting surface 8. The inner peripheral surface 8 extends so as to surround the working space 7 and divides the working space 7. In the present embodiment, the inner peripheral surface 8 is circular when viewed from the central axis direction of the inner peripheral surface 8 (a direction perpendicular to the paper surface of FIG. 1), and defines a cylindrical area. The terahertz wave Lt is sequentially reflected at a plurality of positions (positions P1 to P8 in the example of FIG. 1) on the inner peripheral surface 8 in the working space 7, and then enters the terahertz wave detection device 30. In the present embodiment, the terahertz wave Lt that has passed through the working space 7 a plurality of times propagates to the terahertz wave detecting device 30 located outside the working space 7 by passing through the introduction portion 9a. In the present application, “to pass through the working space 7 a plurality of times” means that a terahertz wave is transferred from one position on a surface (the inner peripheral surface 8 and the introduction portion 9a) defining the working space 7 to another position on the surface. This means that the propagation of the wave Lt is performed twice or more.

The introduction path forming body 11 forms an introduction path 11a extending from the introduction port 7a. The introduction path 11a has an intake port 11b that opens to the outside on the side opposite to the introduction port 7a. The introduction path forming body 11 may be a deformable (for example, deformable) pipe. In this case, the pipe 11 is connected to the space forming body 9. However, the introduction path forming body 11 is not limited to this, and may be any as long as the introduction path 11a is formed inside.

The discharge path forming body 13 forms a discharge path 13a extending from the discharge port 7b. The discharge path 13a has an outlet 13b that opens to the outside on the side opposite to the discharge port 7b. The discharge path forming body 13 may be a deformable (for example, deformable) pipe. In this case, the pipe 13 is connected to the space forming body 9. However, the discharge path forming body 13 is not limited to this, and may be any as long as the discharge path 13a is formed inside.

The gas flow generator 15 generates a gas flow that flows into the working space 7 from the outside through the inlet 7a. The gas flow generator 15 may be, for example, a blower (fan). In the example of FIG. 3, the blower 15 is provided on the discharge path forming body 13. In this case, the blower 15 is a suction device that sucks gas from the outside into the working space 7 through the introduction port 7a by sending the gas in the working space 7 to the outside from the outlet 13b through the outlet 7b and the discharge path 13a. Function. Although not shown, the blower 15 may be provided in the introduction path forming body 11 (for example, the intake port 11b), or in the working space 7 in a region that does not interfere with the terahertz wave Lt (for example, the introduction port 7a or (Near the discharge port 7b).

The rectifying unit 16 is provided in the working space 7 between a region through which the terahertz wave Lt passes (hereinafter, simply referred to as a passing region) and the inlet 7a. The rectification unit 16 reduces the difference in the flow rate of the gas to be inspected between the positions in the passage area. The flow straightening unit 16 may be, for example, a plate-like or mesh-like member (for example, a metal mesh) having a large number of holes formed therein. Such a plate-like or mesh-like member extends two-dimensionally in parallel with the propagation direction of the terahertz wave Lt in the working space 7 and is arranged so as to separate the passage area and the area on the inlet 7a side. .

The interaction unit 20 may include a rectification unit 17 in addition to the rectification unit 16. The rectifying section 17 is provided in the working space 7 between the passage area and the outlet 7b. The rectifying unit 17 reduces the difference in the flow rate of the gas to be inspected between the positions in the passage area. Such a rectifier 17 may have the same configuration as the rectifier 16. That is, the flow regulating unit 17 is, for example, a plate-shaped or mesh-shaped member having a large number of holes formed therein. It may be arranged so as to extend two-dimensionally in parallel with the propagation direction of the terahertz wave Lt in the working space 7 and to separate the passage area from the area on the outlet 7b side.

FIG. 4 is an explanatory diagram of the operation of the inner peripheral surface 8 described above. 4 corresponds to the propagation direction of the terahertz wave Lt. Further, in FIG. 4, broken lines indicate respective positions P0 to P9 in the propagation direction of the terahertz wave Lt. That is, P0 indicates the position of the condenser lens 5b in FIG. 1, P1 to P8 indicate the position (local region) of the inner peripheral surface 8 as shown in FIG. 1, and P9 indicates the position of the condenser lens 18e described later. Indicates the position. In FIG. 4, a polygonal line indicated by a solid line indicates a propagation path of the terahertz wave Lt.

(4) As shown in FIG. 4, the terahertz wave Lt emitted from the nonlinear optical crystal 3 propagates so as to focus on an intermediate point between adjacent pairs of positions P1 to P9. Therefore, the terahertz wave Lt is reflected on the inner peripheral surface 8 while its spread is being adjusted, so that even if it is reflected many times on the inner peripheral surface 8, the terahertz wave Lt is stably guided to the terahertz wave detection device 30.

Each of the local regions P1 to P8 has an arc shape when viewed in the central axis direction of the inner peripheral surface 8. However, each of the local regions P1 to P8 may have another shape that reflects terahertz such that the terahertz is focused at the center between each pair of adjacent local regions as described above. In this case, the inner peripheral surface 8 may not be circular when viewed in the direction of the central axis.
When the terahertz wave Lt is introduced into the working space 7 as parallel light, each of the local regions P1 to P8 may be a plane. In this case, the inner peripheral surface 8 may be a polygon including the planes P1 to P8 when viewed in the direction of the central axis.

The shape of the inner peripheral surface 8 is set so that the terahertz wave introduced into the working space 7 from the introduction part 9a passes through the working space 7 a plurality of times and then propagates outside the working space 7 through the introduction part 9a. It should just be done.

(Configuration of terahertz wave detection device)
The terahertz wave detection device 30 outputs detection data based on the terahertz wave Lt generated by the terahertz wave generation device 10 and having passed through the working space 7 a plurality of times. In the present embodiment, the terahertz wave detection device 30 includes the excitation light source 1, the nonlinear optical crystal 3, the incident optical system 18, and the detector 19.

The excitation light source 1 and the nonlinear optical crystal 3 are shared by the terahertz wave generator 10 and the terahertz wave detector 30 and have the above-described configuration. When the terahertz wave Lt from the working space 7 is incident on the nonlinear optical crystal 3 so as to satisfy the angle phase matching condition for detection, the nonlinear optical crystal 3 generates the terahertz wave Lt and the pump light generated by the pump light source 1. The signal light Ls is generated from Lp.

The angle phase matching condition for detection includes the following energy conservation law and momentum conservation law.
Energy conservation law: ω _p2 = ω _s2 + ω _T2
Law of conservation of momentum: k _p2 = k _s2 + k _T2
Here, ω _p2 is the angular frequency of the pump light Lp and is equal to ω _p1 described above. The excitation light Lp is the excitation light Lp reflected by the reflection mirror 21 in the example of FIG. ω _s2 is the angular frequency of the signal light Ls, ω _T2 is the angular frequency of the terahertz wave Lt, and is equal to ω _T1 described above. Further, k _p2 is a wave vector of the pump light Lp, k _s2 is a wave vector of the signal light Ls, and k _T2 is a wave vector of the terahertz wave Lt incident on the nonlinear optical crystal 3. FIG. 2 shows the relationship between these wave number vectors k _p2 , k _s2 , and k _T2 .

The reflection mirror 21 is a component of the terahertz wave detection device 30, and reflects the excitation light Lp emitted from the excitation light source 1 and reflected at the reflection position Pr to the reflection position Pr again. The excitation light Lp reflected by the reflection mirror 21 is reflected again at the reflection position Pr and is absorbed by the isolator 23. Note that the isolator 23 transmits the excitation light Lp from the excitation light source 1 toward the reflection position Pr.

(4) The incident optical system 18 guides the terahertz wave Lt from the working space 7 to the nonlinear optical crystal 3 and causes the terahertz wave Lt to enter the nonlinear optical crystal 3 so that the angle phase matching condition for detection is satisfied.

In the example of FIG. 1, the incident optical system 18 causes the terahertz wave Lt from the working space 7 to enter the reflection position Pr on the nonlinear optical crystal 3. At this time, the direction in which the incident optical system 18 causes the terahertz wave Lt to enter the nonlinear optical crystal 3 is opposite (directly opposite) to the direction in which the terahertz wave Lt generated in the nonlinear optical crystal 3 is emitted from the nonlinear optical crystal 3. .

The incident optical system 18 may be configured to have a plurality of reflecting mirrors 18a to 18c and a beam splitter 18d, for example, as shown in FIG. The plurality of reflection mirrors 18a to 18c sequentially reflect the terahertz waves Lt from the working space 7 and make the terahertz waves Lt incident on the beam splitter 18d. The beam splitter 18d makes a part of the terahertz wave Lt incident from the reflecting mirror 18c enter the reflecting mirror 5a, and transmits the rest of the terahertz wave Lt. The reflection mirror 5a causes the terahertz wave Lt from the beam splitter 18d to enter the nonlinear optical crystal 3. The reflection mirror 5a is shared by the introduction optical system 5 and the incident optical system 18. Note that the incident optical system 18 may further include a lens 18e for adjusting the degree of convergence (spread) of the terahertz wave Lt. The lens 18e may be a condenser lens.

A part of the terahertz wave Lt emitted from the non-linear optical crystal 3 and reflected by the reflection mirror 5a toward the working space 7 is transmitted through the beam splitter 18d and introduced into the working space 7, and the rest is transmitted to the beam splitter 18d. And is absorbed by the isolator 25. Note that the isolator 25 transmits the terahertz wave Lt traveling from the reflection mirror 18c to the beam splitter 18d.

The detector 19 outputs detection data based on the signal light Ls. The detection data may be spectrum data of the terahertz wave Lt. The spectrum data represents the intensity of each wavelength component of the terahertz wave Lt. Each wavelength of the terahertz wave Lt corresponds to each wavelength of the signal light Ls on a one-to-one basis. The direction in which the signal light Ls is emitted from the nonlinear optical crystal 3 differs depending on the wavelength component of the signal light Ls. Therefore, the detector 19 has a large number of light detection elements 19a arranged on the detection surface as shown in FIG. The light detection element 19a may be, for example, a CCD (Charge Coupled Device). The positions of the large number of light detecting elements 19a correspond to the large number of wavelengths of the terahertz wave Lt, respectively, and this correspondence is determined in advance and set in the detector 19. The detector 19 generates the spectrum data of the terahertz wave Lt based on the intensity of the signal light Ls detected by each light detection element 19a and the wavelength of the terahertz wave Lt corresponding to the light detection element 19a. The spectrum data output from the detector 19 may be displayed on, for example, a display (not shown).

FIG. 5 shows the spectral characteristics of the terahertz wave. In FIG. 5, the horizontal axis indicates the frequency of the terahertz wave, and the vertical axis indicates the intensity of the terahertz wave. The spectrum A in FIG. 5 shows the spectrum of the terahertz wave after passing through the air in which water vapor exists, and each thin line segment extending from the horizontal axis (that is, the position where the intensity is zero) to the vertical axis is in the air. 2 shows an absorption spectrum of a terahertz wave Lt due to water vapor. At the frequency corresponding to each absorption spectrum, the intensity of spectrum A decreases.

スペクトル The spectrum before passing through water vapor corresponding to spectrum A as shown in FIG. 5 has intensity over a continuous wide frequency range. The terahertz wave generator 10 of FIG. 1 can change the frequency of the generated terahertz wave Lt over such a wide frequency range. This change of the frequency is performed, for example, by adjusting the frequency of the pump light Lp. In the first embodiment, the spectrum of the terahertz wave Lt generated by the terahertz wave generator 10 has a certain wavelength width as described above, but the wavelength of the pump light Lp generated by the pump light source 1 is By changing the terahertz wave Lt, the terahertz wave Lt having the center wavelength different from each other may be generated a plurality of times. A range in which these wavelength widths are combined can be a wide wavelength range (that is, the wide frequency range described above).

On the other hand, the target component absorbs the terahertz wave Lt at a plurality (for example, a large number) of specific frequencies in the spectrum of the terahertz wave Lt, for example. Therefore, a combination of absorbed wavelengths can be detected based on the detected spectrum data of the terahertz wave Lt, and the presence or absence of the target component can be inspected based on the combination.

The target component may be a solid component of particles suspended in the test target gas or a gas component. For example, target components include explosive components (NH ₃ , NO, N ₂ O, etc.), nerve gas (Sarin, VX, etc.), and toxic or deleterious components (TBM, CHCH ₃ OH, H ₂ S, HCl, HCN). , NH ₃ , SO ₂ , UF ₆ ), components related to drug crime (drugs, evacuated herbs, thinners, etc.), components related to natural disasters (eg, volcanic gas: H ₂ S, CO ₂ , SO _2, etc.), and environmental issues component (freon and greenhouse _{_{gases: HFCs, PFCs, CO 2,}} CH 4, N 2 O, SF , etc. ₆₎ may be.

(Effect of First Embodiment)
According to the above-described first embodiment, the terahertz wave Lt introduced into the working space 7 passes through the working space 7 a plurality of times by being reflected by the reflection surface 8. The sum can be increased. Thereby, the detection sensitivity of the target component contained in the test target gas can be increased. For example, as described above, by reflecting the terahertz wave Lt at a plurality of places (many places) on the inner peripheral surface 8, it is possible to detect the target component with high sensitivity.

In the inspection using terahertz waves, even if the gas to be inspected contains various components and the amount of the target component is very small, there is no need to pretreat the gas to be inspected. Inspection can be performed at high speed (in real time).
Further, for example, by introducing a large amount of the gas to be inspected into the working space 7 from the inlet 7a, it is possible to inspect the large amount of the gas to be inspected for the presence of the target component.
Further, since the inlet 7a is indirectly communicated with the outside via the inlet 11b, the inlet 11b is arranged in the space region R (FIG. 3) to be inspected, so that the space region R can be inspected. Can be introduced into the working space 7 as a gas to be inspected.

For example, when the target component is an explosive component, a component of toxicity, a deleterious substance, or a component related to drug crime, the inlet 11b of the gas detection device is arranged in a ticket gate which is a doorway of a person at a train station. Or at an airport, a building, or a security gate in a building. As a result, a gas to be inspected containing a target component (suspended particles or gas) from a person passing through a ticket gate or a security gate, or clothes or belongings of the person, is introduced into the working space 7 from the intake port 11b and is inspected at high speed. can do. When the target component is a component related to a natural disaster, the intake 11b is arranged near a volcano (crater) that needs to be monitored, and the presence or absence of the component is checked to determine the activity status of the volcano. Can be monitored. When the target component is a component relating to an environmental problem, the intake port 11b can be arranged at a monitoring location of the component.

When the introduction path forming body 11 is a deformable (for example, deformable) pipe, the pipe 11 is deformed in accordance with the space region R to be inspected, so that the intake port 11b at the tip of the pipe 11 is formed. Can be easily arranged in the space region R. For example, when the space region R is inside a bag or suitcase carried by a person, the bag or the suitcase is opened at the security gate, and the intake port 11b of the pipe 11 is easily arranged inside the bag or the suitcase. Can be. Next, the gas inside the bag or the suitcase can be introduced into the working space 7 as the gas to be inspected by the gas flow generator 15.

Since the nonlinear optical crystal 3 is shared by the terahertz wave generator 10 and the terahertz wave detector 30, the configuration of the inspection apparatus 100 can be made compact.

[Second embodiment]
FIG. 6 shows a configuration of an inspection device 100 according to the second embodiment of the present invention. In the second embodiment, the terahertz wave generator 10 may be configured to generate a single-wavelength terahertz wave Lt and introduce the terahertz wave Lt into the working space 7. Therefore, in the second embodiment, the terahertz wave generator 10 further includes a seed light source 29 in addition to the configuration of the first embodiment. In the second embodiment, the points that are not described are the same as those in the first embodiment, and thus description thereof is omitted.

In the second embodiment, for example, the wavelength of the excitation light Lp generated by the excitation light source 1 is kept constant, and the wavelength of the seed light L _seed generated by the seed light source 29 is continuously changed. The wavelength of the terahertz wave Lt can be continuously changed. The wavelength range combining the respective wavelengths of the terahertz wave Lt can be set to a wide wavelength range (for example, the wide frequency range in FIG. 4). In order to perform inspection over such a wavelength range, a terahertz wave Lt of the wavelength is introduced into the working space 7 by the terahertz wave generator 10 for each wavelength in the wavelength range, and the terahertz wave Lt having passed through the working space 7 a plurality of times. Based on the terahertz wave Lt, the detected intensity of the terahertz wave Lt is generated and output as detection data by the terahertz wave detection device 30. Such a configuration is described in more detail below.

The seed light source 29 generates seed light L _seed having a single wavelength, and causes the seed light L _seed to enter the nonlinear optical crystal 3. In the example of FIG. 6, a part of the seed light L _seed from the seed light source 29 is reflected by the beam splitter 31 and enters the nonlinear optical crystal 3.

The seed light source 29 generates, for example, a seed light L _seed having a single frequency lower by about 1 to 3 THz than the frequency of the excitation light Lp. The seed light source 29 is configured such that the single frequency of the seed light L _seed to be generated is variable. For example, when a person operates an appropriate operation unit provided on the seed light source 29, the single frequency of the seed light L _seed generated by the seed light source 29 is changed. The seed light source 29 may be, for example, a tunable semiconductor laser, but is not limited to this.

In this case, the nonlinear optical crystal 3 generates the terahertz wave Lt by satisfying the next angle phase matching condition for generation. The angle phase matching condition for this generation includes the following energy conservation law and momentum conservation law.
Energy conservation law: ω _p1 = ω _seed + ω _T1
Momentum conservation law: k _p1 = k _seed + k _T1
Here, ω _p1 , ω _T1 , k _p1 , and k _T1 are the same as in the first embodiment. ω _seed is the angular frequency of the seed light L _seed , and k _seed is the wave vector of the seed light L _seed .

FIG. 7 shows a part of FIG. FIG. 7 shows the relationship among wave number vectors k _p1 , k _seed , and k _T1 . In the example of FIG. 7, k _seed is a wave number vector immediately before the seed light L _seed is reflected at the reflection position Pr.

In the second embodiment, the nonlinear optical crystal 3 generates the terahertz wave Lt having a single wavelength by the excitation light Lp and the seed light L _seed that satisfy the angle phase matching condition for generation, and emits the terahertz wave Lt. . The terahertz wave Lt may be emitted from the end face 3b in a direction substantially orthogonal to the end face 3b of the nonlinear optical crystal 3, as shown in FIG.

The terahertz wave Lt emitted from the nonlinear optical crystal 3 is introduced into the working space 7 by the introduction optical system 5 and reflected a plurality of times at a plurality of positions P1 to P8 on the inner peripheral surface 8 as in the first embodiment. The light passes through the working space 7 a plurality of times, and is again incident on the nonlinear optical crystal 3 by the incident optical system 18. Thus, the signal light Ls is generated according to the angle phase matching condition for detection, as in the first embodiment, and the signal light Ls enters the detector 19. In this case, the angle phase matching conditions for detection are the same as those in the first embodiment, and the wave vectors k _p2 , k _s2 , and k _T2 of the excitation light Lp, the signal light Ls, and the terahertz wave Lt in the momentum conservation law. Is shown in FIG.

A part of the signal light Ls from the nonlinear optical crystal 3 passes through the beam splitter 31 and enters the detector 19, and the rest is reflected by the beam splitter 31 and absorbed by the isolator 33. The isolator 33 transmits the seed light L _seed traveling from the seed light source 29 to the beam splitter 31.

In the second embodiment, the detector 19 may generate an electric signal having a magnitude indicating the intensity of the received signal light Ls as detection data and output the electric signal. This detection data represents the intensity of the terahertz wave Lt.

According to the second embodiment, the single frequency of the seed light L _seed generated by the seed light source 29 is continuously changed, and the detector 19 outputs the above-described electric signal for each frequency of the seed light L _seed . That is, for each frequency of the seed light L _seed , a terahertz wave Lt having a single frequency corresponding to the frequency is emitted from the nonlinear optical crystal 3 and passes through the working space 7 a plurality of times. , Whereby the signal light Ls is generated, and an electric signal having a magnitude indicating the intensity of the signal light Ls is output from the detector 19. Each frequency of the signal light Ls is known, and has a one-to-one correspondence with the frequency of the generated terahertz wave Lt, and this correspondence is known in advance. Therefore, based on this correspondence and the electric signal output from the detector 19 for each frequency of the seed light L _seed , the spectrum data of the detected terahertz wave Lt can be generated.

でも In the above-described second embodiment, the same effects as in the first embodiment can be obtained. For example, also in the second embodiment, as shown in FIG. 4 described above, the terahertz wave Lt is reflected on the inner peripheral surface 8 while its spread is adjusted. Then, it is guided to the terahertz wave detection device 30.

In addition, for example, the target component absorbs the terahertz wave Lt at a plurality of specific frequencies in the spectrum of the terahertz wave Lt, and the ratio of the absorption amount of the terahertz wave Lt at these specific frequencies to each other is specific. Ratio.
On the other hand, by making the intensity of the excitation light Lp generated by the excitation light source 1 and the intensity of the seed light L _seed generated by the seed light source 29 constant and changing the wavelength of the seed light L _seed or the excitation light Lp, the terahertz wave is obtained. The wavelength can be changed while keeping the intensity of Lt constant. Thereby, the combination of the absorbed wavelengths is detected from the spectrum data based on the output data output from the detector 19 for each frequency of the terahertz wave Lt, and the ratio of the amount of absorption at each wavelength to each other is obtained. Can be. Therefore, the target component can be detected based on the combination and the ratio.

The present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made within the technical idea of the present invention. For example, the inspection apparatus 100 according to the first embodiment or the second embodiment of the present invention may not have all of the above-described plural items, and may have only some of the above-described plural items. Is also good.

Also, any of the following Modifications 1 to 12 may be used alone, or an appropriate combination of two or more of Modifications 1 to 12 may be arbitrarily adopted. In this case, the points not described below are the same as those described above.

(Modification 1)
In the above-described second embodiment, the single frequency of the terahertz wave Lt emitted from the nonlinear optical crystal 3 may be changed by changing the angle at which the excitation light Lp from the excitation light source 1 enters the nonlinear optical crystal 3. . For example, by changing the angle of a reflection mirror (not shown) that reflects the excitation light Lp from the excitation light source 1 and enters the nonlinear optical crystal 3, the incident angle of the excitation light Lp to the nonlinear optical crystal 3 may be changed. .

(Modification 2)
In the above-described second embodiment, a resonator that amplifies idler light Li may be provided instead of the seed light source 29. This resonator includes, for example, first and second reflection mirrors 27a and 27b that reflect idler light Li, as shown in FIG. Although FIG. 8 illustrates the nonlinear optical crystal 3 and the reflection mirrors 27a and 27b, illustration of other components of the inspection apparatus 100 is omitted.

Among the idler light Li generated by the excitation light Lp in the nonlinear optical crystal 3, the idler light Li propagating in a specific direction is amplified by being repeatedly reflected by the first and second reflection mirrors 27a and 27b. Thus, the single-frequency terahertz wave Lt corresponding to the amplified idler light Li is generated in the nonlinear optical crystal 3 and emitted from the nonlinear optical crystal 3 in accordance with the above-described angular phase matching condition for generation.

In this case, for example, the single frequency of the terahertz wave Lt emitted from the nonlinear optical crystal 3 may be changed by changing the angle at which the excitation light Lp from the excitation light source 1 enters the nonlinear optical crystal 3. Alternatively, the wavelength of the terahertz wave Lt emitted from the nonlinear optical crystal 3 may be changed by changing the wavelength of the excitation light Lp generated by the excitation light source 1.

(Modification 3)
In the inspection apparatus 100 for achieving the above-described first or second object of the present invention, the terahertz wave generator 10 is not limited to the configuration shown in each drawing, and can generate the terahertz wave Lt. Any device that can change the wavelength of Lt may be used.

(Modification 4)
In the inspection apparatus 100 for achieving the above-described first object of the present invention, the inspection target through which the terahertz wave Lt passes may be the inspection target gas as described above, or may be a solid, a powder, or a liquid. It may be. When the inspection target is a solid, a powder, or a liquid, the interaction unit 20 includes the space forming body 9 that forms the working space 7 in which the inspection target exists. It is not necessary to have. In addition, the working space 7 is not provided with the inlet 7a and the outlet 7b, but, for example, the space forming body 9 may be formed with an opening communicating the working space 7 with the outside. The test object may be arranged in the working space 7 through this opening. When the inspection target is a powder or a liquid, the powder or the liquid may be placed in a container and placed in the working space 7. The inspection target may be arranged, for example, in a region where the terahertz wave Lt is reflected by the reflection surface (inner peripheral surface) 8 and passes through a plurality of times in the working space 7. Note that the opening may be formed at a location other than the inner peripheral surface 8.

(Modification 5)
In the first embodiment or the second embodiment described above, the terahertz wave Lt is introduced into the working space 7 through the introduction part 9a and propagates outside the working space 7 through the same introduction part 9a, but the present invention is not limited to this. Not done. That is, the space forming body 9 may include an exit portion that propagates the terahertz wave Lt to the outside of the working space 7 in addition to the introduction portion 9a. The exit portion is formed of a material through which the terahertz wave Lt passes. In this case, the terahertz wave Lt is introduced into the working space 7 through the introduction part 9a, passes through the working space 7 a plurality of times, and then enters the terahertz wave detection device 30 outside the working space 7 through the exit part.

The shape of the inner peripheral surface 8 is set so that the terahertz wave introduced into the working space 7 from the introduction portion 9a propagates through the working space 7 to the outside of the working space 7 after passing through the working space 7 a plurality of times. It should just be done.

(Modification 6)
In the inspection apparatus 100 for achieving the above-described third object of the present invention, the interaction unit 20 may not be provided. That is, the terahertz wave Lt generated by the terahertz wave generation device 10 may interact with the inspection target (gas, solid, powder, or liquid) and thereafter enter the same nonlinear optical crystal 3. . As described above, the terahertz wave Lt incident on the nonlinear optical crystal 3 may be transmitted through the inspection target in the inspection target region or reflected or scattered by the inspection target. The terahertz wave Lt interacts with the test object when transmitting through the test object or reflecting or scattering at the test object. That is, some frequency components of the terahertz wave Lt are absorbed by the inspection target.

(Modification 7)
In the first embodiment or the second embodiment described above, one or both of the nonlinear optical crystal 3 and the excitation light source 1 may not be shared by the terahertz wave generator 10 and the terahertz wave detector 30. For example, the terahertz wave generator 10 and the terahertz wave detector 30 may have different nonlinear optical crystals, respectively. In this case, the excitation light Lp from the excitation light source 1 of the terahertz wave generation device 10 may be guided and incident on the nonlinear optical crystal of the terahertz wave detection device 30 by an appropriate optical system. Excitation light Lp from a separately provided excitation light source may be incident. Thereby, the signal light Ls is generated in the terahertz wave detection device 30.

(Modification 8)
In the first or second embodiment described above, one or both of the introduction path forming body 11 and the discharge path forming body 13 may be omitted. In a case where both the introduction path forming body 11 and the discharge path forming body 13 are omitted, the blower 15 may be provided at the introduction port 7a or the discharge port 7b, or in the working space 7 in a region that does not interfere with the terahertz wave Lt. It may be provided.

(Modification 9)
In the above-described first or second embodiment, the number of times that the terahertz wave Lt is reflected on the reflecting surface (inner peripheral surface) 8 in the working space 7 is one or more (many times). You may. In addition, if the terahertz wave Lt is reflected one or more times by the inner peripheral surface 8 and passes through the working space 7 a plurality of times and is detected by the terahertz wave detecting device 30, the shape of the inner peripheral surface 8 is the above-described shape. It is not limited to.

(Modification 10)
The gas flow generator 15 may not be provided. That is, when the interaction unit 20 is installed at a place where the gas to be inspected (for example, volcanic gas) naturally flows into the working space 7 through the inlet 7a and flows out to the outside through the outlet 7b (for example, outdoors). The gas flow generator 15 may not be provided.

(Modification 11)
In the above-described second embodiment, the terahertz wave detection device 30 may not have the nonlinear optical crystal 3. In this case, the terahertz wave Lt from the working space 7 enters the detector 19. The detector 19 generates and outputs an electric signal indicating the intensity of the incident terahertz wave Lt. Such a detector 19 includes, for example, an absorber and a thermoelectric conversion element. The absorber generates heat by absorbing the terahertz wave Lt. The thermoelectric conversion element is attached to the absorber and generates and outputs the electric signal having a magnitude corresponding to the amount of heat generated by the absorber as detection data.

(Modification 12)
FIG. 9 shows a configuration of an inspection apparatus 100 according to a twelfth modification. FIG. 10 is a view taken along the line XX in FIG. As shown in FIG. 9, the space forming body 9 is formed with an inlet 9b through which the test object T enters the working space 7 from the outside and an outlet 9c through which the test object T exits from the working space 7 to the outside. The inlet 9b and the outlet 9c are located on the inner peripheral surface 8 so as to be shifted from the respective positions P1 to P8 where the terahertz wave Lt is reflected. As shown in FIG. 10, the space forming body 9 has a surface 12 that partitions the working space 7, and this surface 12 may be a horizontal plane. In the twelfth modification, the gas flow generator 15 may not be provided.

In the twelfth modification, the inspection target T to be present in the working space 7 may be other than gas, for example, a person or an object. The inspection object T enters the working space 7 from the inlet 9b as shown by the dashed arrow A in FIG. 9, and then goes out of the working space 7 from the outlet 9c. For example, the inspection target T may be transported by a transport device (for example, a belt conveyor) so as to enter the working space 7 from the inlet 9b and exit the working space 7 from the outlet 9c. This transport device is provided so as not to interfere with the propagation path of the terahertz wave Lt in the working space 7. When the inspection target T is a person, the person may walk, enter the working space 7 from the entrance 9b, and go out of the working space 7 from the exit 9c. A person may walk on the horizontal plane 12 of FIG.

Further, for example, after the test object T enters the working space 7, it temporarily stops at the center of the working space 7. This central portion is located on the central axis of the inner peripheral surface 8 which is circular in FIG. The terahertz wave Lt is generated by the terahertz wave generator 10 in a state where the test object T is stopped at the center of the working space 7, so that the terahertz wave Lt is not transmitted through the test object T (not transmitted through the test object T). Pass many times (9 times in FIG. 9). Therefore, it is possible to inspect with high sensitivity whether or not the target component (suspended particles or gas) is contained in the air surrounding the inspection target T. That is, since the air surrounding the inspection target T includes the component generated from the inspection target T, it is possible to inspect with high sensitivity whether the component is the target component.

One space which serves as both the inlet 9b and the outlet 9c may be formed in the space forming body 9. In this case, the other points of the twelfth modification are the same as those described above. FIG. 9 shows a configuration in which the modification 12 is employed for the inspection apparatus 100 of the first embodiment. However, even if the above-described modification 12 is employed for the inspection apparatus 100 of the second embodiment. Good.

1 excitation light source, 3 nonlinear optical crystal, 3a side face, 3b end face, 5 introduction optical system, 5a reflection mirror, 5b lens, 7 working space, 7a introduction port, 7b exhaust port, 8 reflection surface (inner peripheral surface), 9 space Forming body, 9a inlet, 9b inlet, 9c outlet, 10 terahertz wave generator, 11 inlet forming body (tube), 11a inlet, 11b inlet, 13 outlet forming body (tube), 13a outlet, 13b outlet, 15 gas flow generator (blower), 16 rectifier, 17 部 rectifier, 18 incident optical system, 18a ～ 18c reflector mirror, 18d beam splitter, 18e condenser lens, 19 detector, 19a photodetector, 20 interaction unit, 21 reflection mirror, 23 isolator, 25 isolator, 27a, 27b reflection mirror, 2 Seed source, 30 terahertz wave detection apparatus, 31 a beam splitter, 33 isolator, 100 inspecting apparatus, Pr reflection position, Li idler light, Lp excitation light, Lt terahertz wave, Ls signal light, T inspected

Claims

A terahertz wave generator for generating a terahertz wave,
An interaction unit having an operation space in which the terahertz wave is introduced and an inspection target is present;
A terahertz wave detection device that generates detection data based on the terahertz wave that has passed through the working space by interacting with the test object in the working space, and outputs the detection data,
The interaction unit has a reflecting surface that reflects the terahertz wave in the working space, and the terahertz wave passes through the working space a plurality of times by being reflected by the reflecting surface, and An inspection device using a terahertz wave, which is incident on the terahertz wave detection device located outside the space.
A terahertz wave generator for generating a terahertz wave,
The terahertz wave and the gas to be tested are introduced, and an interaction unit having an action space for allowing the two to interact with each other,
A terahertz wave detection device that generates detection data based on the terahertz wave that has passed through the working space and outputs the detection data,
The interaction unit includes a space forming body that forms the working space,
An inspection apparatus using terahertz waves, wherein the working space has an inlet communicating with the outside, and an external gas can flow into the working space through the inlet as a gas to be inspected.
The inspection device according to claim 2, wherein the interaction unit includes a gas flow generating device that generates a gas flow flowing into the working space from the outside through the inlet.
An introduction path forming body that forms an introduction path extending from the introduction port,
The inspection device according to claim 2, wherein the introduction path has an intake port that opens to the outside on a side opposite to the introduction port.
The inspection device according to claim 4, wherein the introduction path forming body is a deformable tube.
The interaction unit has a reflecting surface that reflects the terahertz wave in the working space, and the terahertz wave passes through the working space a plurality of times by being reflected by the reflecting surface, and The inspection device according to any one of claims 2 to 5, wherein the inspection device is configured to enter the terahertz wave detection device located outside the space.
The reflection surface is an inner peripheral surface that extends so as to surround the working space and divides the working space, and the terahertz wave is reflected at a plurality of positions on the inner peripheral surface in the working space in order, and then the terahertz wave is reflected. The inspection device according to claim 1, wherein the inspection device is configured to be incident on a wave detection device.
The inspection device according to claim 7, wherein the inner peripheral surface is circular when viewed from a center axis direction of the inner peripheral surface.
The working space has an outlet, and the gas to be inspected in the working space is allowed to flow outside through the outlet.
The inlet and the outlet are located so as to sandwich a region through which the terahertz wave passes in the working space,
The interaction unit comprises:
The inspection according to any one of claims 2 to 6, further comprising a rectification unit provided between the region and the inlet, and configured to reduce a difference in flow rate of the inspection target gas between positions in the region. apparatus.
The terahertz wave generator includes an excitation light source that generates excitation light, and a nonlinear optical crystal that generates a terahertz wave when the excitation light is incident so as to satisfy an angle phase matching condition for generation.
The terahertz wave detection device, the non-linear optical crystal that generates signal light from the terahertz wave and the excitation light by the terahertz wave from the working space is incident so as to satisfy the angular phase matching condition for detection, A detector that outputs detection data based on the signal light,
The inspection device according to any one of claims 1 to 9, wherein the nonlinear optical crystal is shared by the terahertz wave generator and the terahertz wave detector.
A terahertz wave generator that generates a terahertz wave and introduces the terahertz wave into an inspection target area;
A terahertz wave detection device that outputs detection data based on the terahertz wave that has passed through the inspection target area,
The terahertz wave generator includes an excitation light source that generates excitation light, and a nonlinear optical crystal that generates a terahertz wave when the excitation light is incident so as to satisfy an angle phase matching condition for generation.
The terahertz wave detection device, the non-linear optical crystal that generates signal light from the terahertz wave and the excitation light by being incident so that the terahertz wave from the inspection target area satisfies the angular phase matching condition for detection A detector that outputs detection data based on the signal light,
An inspection device using a terahertz wave, wherein the nonlinear optical crystal is shared by the terahertz wave generator and the terahertz wave detector.
(A) generating a terahertz wave,
(B) introducing the terahertz wave into the working space where the test object is present, and causing the terahertz wave to interact with the test object in the working space;
(C) generating detection data based on the terahertz wave from the working space, outputting the detection data,
In the above (B), an inspection method using a terahertz wave, wherein the terahertz wave passes through the working space a plurality of times by being reflected by a reflection surface in the working space.
(A) generating a terahertz wave,
(B) introducing the terahertz wave into the working space where the gas to be tested is present, and allowing the terahertz wave to interact with the gas to be tested in the working space;
(C) generating detection data based on the terahertz wave from the working space, outputting the detection data,
An inspection method using terahertz waves, wherein the working space has an inlet communicating with the outside, and an external gas flows into the working space through the inlet as the gas to be inspected.
(A) generating a terahertz wave,
(B) introducing the terahertz wave into a region to be inspected,
(C) generating detection data based on the terahertz wave passed through the inspection target area, outputting the detection data,
In the above (A), the terahertz wave is generated by the excitation light being incident on the nonlinear optical crystal so as to satisfy the angle phase matching condition for generation,
In (C), the terahertz wave from the inspection target region is incident on the nonlinear optical crystal so as to satisfy the angle phase matching condition for detection, so that signal light is generated from the terahertz wave and the excitation light. Generating the detection data based on the signal light;
An inspection method using a terahertz wave, wherein the nonlinear optical crystal is shared by the above (A) and (C).