Inspection equipment

Abstract

To miniaturize a test device checking belongings of persons on the basis of collected electromagnetic waves in comparison with a case in which a composite mirror is not used.SOLUTION: A composite mirror 11 has a plurality of concave surface mirrors M0, M1, ..., Mi, Mi+1, .... Curves of the concave surface mirrors M0, M1, ..., Mi, Mi+1, ... passing through an xy plane are represented by respective functions f0(x), f1(x), ..., fi(x), fi+1(x), ... of an independent variable x. A plurality of these functions is a parabola each having a common optical axis I and a focal point P, thus a plurality of concave surface mirrors M forming the composite mirror 11 is a parabolic surface mirror. The concave surface mirror M is all cut off so as not to exceed a thickness t. That is, a y-coordinate of the concave surface mirror M is equal to or more than 0 and equal to or less than t.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This invention relates to a technology for an inspection device that inspects a person's belongings based on electromagnetic waves. [Background technology]

[0002] As scanners that inspect the internal condition of an object being inspected, body scanners used for body checks at airports and the like are known (see, for example, Patent Document 1).

[0003] Furthermore, Patent Document 2 discloses a mobile scanner that detects the position of moving objects (mobile bodies) such as pedestrians and switches the propagation direction of terahertz waves according to the detected position. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-36680 [Patent Document 2] Japanese Patent Publication No. 2019-190951 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Methods for imaging objects using electromagnetic waves include active imaging, which involves irradiating an object with electromagnetic waves and detecting the transmitted or reflected waves to create an image, and passive imaging, which involves detecting electromagnetic waves emitted from the object itself to create an image.

[0006] For example, terahertz waves are electromagnetic waves with frequencies between approximately 100 GHz and 10 THz. While these terahertz waves are used in the active imaging described above, they are also emitted in small amounts from the human body and belongings, and are therefore used in the passive imaging type walk-through baggage detection devices described above, which use the difference in the amount of radiation emitted to detect concealed belongings.

[0007] In order to receive the weak terahertz waves radiated from an object, the light receiving system needs to be capable of handling a wide band. However, since a lens has chromatic aberration, it is not suitable for a wide band. Further, if electromagnetic waves radiated from a person's entire body are to be collected by a single parabolic mirror, a corresponding depth is required, which makes the apparatus large and makes it difficult to reduce the space occupied. This also applies to the case of active imaging.

[0008] One object of the present invention is to reduce the size of an inspection apparatus that inspects a person's belongings based on the collected electromagnetic waves as compared to the case where the composite mirror according to the present invention is not used.

Means for Solving the Problem

[0009] In order to solve the above-described problems, the present invention provides, as a first aspect, an inspection apparatus that inspects a person's belongings based on electromagnetic waves collected by a composite mirror in which a plurality of concave mirrors having different focal lengths are arranged such that their optical axes and foci overlap.

[0010] According to the inspection apparatus of the first aspect, it is possible to reduce the size of an inspection apparatus that inspects a person's belongings based on the collected electromagnetic waves as compared to the case where the composite mirror according to the present invention is not used.

[0011] In the inspection apparatus of the first aspect, the composite mirror is represented using a constant p, c1, and an independent variable x indicating the distance from the optical axis A configuration in which the composite mirror has a curved surface obtained by rotating a function curve of JPEG0007836380000001.jpg17143 about the optical axis may be adopted as a second aspect.

[0012] According to the inspection apparatus of the second aspect, it is possible to reduce the size of an inspection apparatus that inspects a person's belongings based on the collected electromagnetic waves.

[0013] In the inspection apparatus of the first aspect, a configuration in which the concave mirror is a parabolic mirror may be adopted as a third aspect.

[0014] According to the inspection apparatus of the third embodiment, parallel light (electromagnetic waves traveling in parallel) from the object to be inspected can be focused into a single focal point.

[0015] A fourth embodiment may be adopted in which, in the inspection apparatus of any one of the first to third embodiments, the composite mirror is positioned so as not to obstruct the movement of the person.

[0016] According to the inspection apparatus of the fourth embodiment, the composite mirror does not obstruct the movement of people.

[0017] In the inspection apparatus of any one of the first to fourth embodiments, a fifth embodiment may be adopted in which the composite mirror has no gap when viewed from the focal point.

[0018] According to the inspection apparatus of the fifth embodiment, even if the multiple concave mirrors constituting the composite mirror are separated from each other, the reflected light reaching the focal point is continuous.

[0019] In an inspection apparatus according to any one of the first to fifth embodiments, a sixth embodiment may be adopted in which an optical system arranged at the focal point guides the electromagnetic waves collected by the composite mirror to a detector.

[0020] According to the inspection apparatus of the sixth embodiment, the optical system guides electromagnetic waves from the focal point to the detector.

[0021] A seventh embodiment may be adopted in which the inspection apparatus of the sixth embodiment is configured such that the optical system is a polygon mirror.

[0022] According to the inspection apparatus of the seventh embodiment, a wide area can be inspected by rotating the optical system, which is a polygon mirror, and scanning the object to be inspected. [Brief explanation of the drawing]

[0023] [Figure 1] A plan view showing an example of an inspection system 9 according to an embodiment of the present invention, viewed from above. [Figure 2]A conceptual diagram illustrating the height direction of inspection device 1. [Figure 3] A diagram to explain a parabolic mirror. [Figure 4] A diagram showing an example of a composite mirror 11 housed in the inspection device 1. [Figure 5] This figure shows an example of how the composite mirror 11 inspects electromagnetic waves emitted from an object of length Lz. [Figure 6] A diagram showing an example of multiple concave mirrors that make up the composite mirror 11. [Figure 7] This figure shows an example of an inspection device 1 that uses a polygon mirror in the optical system 12. [Figure 8] This figure shows an example of a composite mirror 11 with no gaps when viewed from the focal point P. [Figure 9] A diagram showing examples of the shapes of multiple concave mirrors M that can be represented by a single function. [Modes for carrying out the invention]

[0024] <Embodiment> <Configuration of the inspection device> In the following diagrams, the space in which each component is arranged is represented as the XYZ right-handed coordinate system, or the xyz right-handed coordinate system. Furthermore, among the coordinate symbols shown in the diagrams, a circle with a point inside represents an arrow pointing from the back of the page to the front, while a circle with two intersecting lines inside represents an arrow pointing from the front of the page to the back. In space, the direction along the x-axis is called the x-axis direction. Within the x-axis direction, the direction in which the x component increases is called the +x direction, and the direction in which the x component decreases is called the -x direction. The y and z components, and the X, Y, and Z components, are defined similarly to the x component.

[0025] Figure 1 is a plan view showing an example of an inspection system 9 according to an embodiment of the present invention, viewed from above. The inspection system 9 is a system for inspecting the belongings of a person Q walking down a passageway, and a total of four inspection devices 1 are placed two on each side of the passageway, in positions that do not obstruct the passageway. This passageway is a passageway with a width W extending in the Y-axis direction in the XYZ right-handed coordinate system, and includes the path of movement of person Q as they walk. Since all four inspection devices 1 are placed in positions that do not obstruct the passageway, they do not obstruct the path of movement of person Q. In Figure 1, the -Z direction is downward, i.e., the direction of gravity, and the X-axis direction is the direction of the width of the passageway.

[0026] Each of the four inspection devices 1 receives (or receives) electromagnetic waves such as terahertz waves emitted in direction D from person Q and their belongings. As person Q walks (moves) in the +Y direction, the four inspection devices 1 scan person Q and their belongings in the Y-axis direction and the X-axis direction (i.e., horizontal direction). In addition, the four inspection devices 1 scan person Q and their belongings in the Z-axis direction.

[0027] Figure 2 is a conceptual diagram illustrating the height direction of the inspection device 1. The belongings worn by person Q are located in the area from above the knees to below the neck, for example, as shown by the diagonal lines in Figure 2. Therefore, the inspection device 1 needs to inspect the area along the Z-axis, from the knee position H1 to the neck position H2 of person Q walking on the floor surface G with the aforementioned passageway. The length Lz along the Z-axis of this area is, for example, 1200 millimeters.

[0028] Figure 3 is a diagram illustrating a parabolic mirror. A parabola passing through the origin O is drawn in the xy-plane shown in Figure 3. This parabola is the curve connecting (x,y) when the dependent variable y is expressed as a quadratic function of the independent variable x. Here, we take the focus P on the y-axis and denote its y-component as p. In this case, the dependent variable y is expressed by the following equation (1).

[0029]

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[0030] With a parabolic mirror, if the incident angle of the electromagnetic wave received at focal point P exceeds two right angles, i.e., 2π radians, the incident light beams will face each other, making it difficult for the optical system to convert them into collimated light (parallel light) and guide them to the detector. Therefore, generally, the y-components of endpoints E1 and E2 of this parabolic mirror do not exceed p, which is the y-component of focal point P. For example, if the y-components of endpoints E1 and E2 are the same as p, which is the y-component of focal point P, then the distance from endpoint E1 to endpoint E2 is 4p.

[0031] Therefore, when inspecting a single parabolic mirror with the aforementioned length Lz, its depth is Lz / 4. If the aforementioned length Lz is 1200 millimeters, the depth of the parabolic mirror will be 300 millimeters. In other words, when inspecting a single parabolic mirror with a height of, for example, 1200 millimeters, the inspection device 1 needs to be large enough to accommodate a parabolic mirror with a depth of 300 millimeters.

[0032] <Combined mirror configuration> Figure 4 shows an example of a composite mirror 11 housed in the inspection device 1. Figure 5 shows an example of the composite mirror 11 inspecting electromagnetic waves emitted from an object of inspection with length Lz. As described above, the inspection device 1 does not obstruct the movement of person Q, and the composite mirror 11 is housed in the inspection device 1. Therefore, the composite mirror 11 shown in Figures 4 and 5 does not obstruct the movement of person Q.

[0033] Figure 4 shows a view of the inside of the inspection device 1 in the -Z direction. The xyz right-handed coordinate system is defined such that the +x direction coincides with the +Z direction and the -y direction coincides with the direction D in which electromagnetic waves are received. The inspection device 1 shown in Figure 4 includes a composite mirror 11, an optical system 12, and a detector 13.

[0034] The optical axis I of the composite mirror 11 extends in a direction parallel to direction D. An optical system 12 is positioned at the focal point P on the optical axis I. This optical system 12 is, for example, a parabolic mirror, which adjusts the electromagnetic waves collected by the composite mirror 11 so that their propagation direction is parallel, and guides them to a detector 13 positioned on the optical axis I. In other words, the inspection device 1 having this optical system 12 is an example of an inspection device that uses an optical system positioned at the focal point to guide the electromagnetic waves collected by the composite mirror to a detector.

[0035] As shown in Figure 5, the thickness of the composite mirror 11 in the y-axis direction is less than one-quarter of the length Lz. This is because the composite mirror 11 is not a single parabolic mirror, but is formed by arranging multiple concave mirrors with different focal lengths so that their optical axes I and focal points P overlap.

[0036] <Detailed configuration of the composite mirror> Figure 6 shows an example of multiple concave mirrors that make up the composite mirror 11. Figure 6 shows a cross-section of the composite mirror 11, which is a body of revolution with the y-axis as its center of rotation, cut by the xy-plane which contains the y-axis. The y-axis coincides with the optical axis I of the composite mirror 11.

[0037] This composite mirror 11 consists of multiple concave mirrors M0, M1, ..., M i M i+1 It has a concave mirror M (hereinafter, when these are not distinguished, they are simply referred to as M).

[0038] The subscripts i of these multiple concave mirrors M are integers starting from 0, and when subscript i=0, the concave mirror M0 contains the origin O. As subscript i increases, the concave mirror M moves further away from the y-axis.

[0039] Concave mirror M0, M1,…, M i M i+1, … The curves passing through the xy plane are functions f0(x), f1(x), …, f i (x), f i+1 (x), … of the independent variable x respectively. These multiple functions shown in Fig. 6 are all parabolas having a common optical axis I and a focus P. That is, the multiple concave mirrors M constituting the compound mirror 11 shown in Fig. 6 are mirrors in the shape of a surface obtained by rotating the above-described parabola around the y-axis respectively, that is, paraboloid mirrors.

[0040] y = f i (x), generally speaking, has a y coordinate on the y-axis of y i (y i ≦0), and is a parabola with a focus P(0, p), so it is represented by the following formula (2). Here, y0 = 0 and i = 0, 1, 2, … (an integer starting from 0).

[0041]

Equation

[0042] Also, all the concave mirrors M are tangent to the straight line indicated by y = t at their respective outer circumferences. And the x coordinates of the outer circumferences of the multiple concave mirrors M i (i ≧ 0) all coincide with the x coordinates of the inner circumferences of the adjacent concave mirrors M i+1 on the outside. That is, there is no gap when looking at the compound mirror 11 composed of these multiple concave mirrors M in the y-axis direction.

[0043] Here, let the x coordinate of the point a i where y = f i (x) shown by the formula (2) is tangent to the straight line indicated by y = t be x i (x i > 0). The perpendicular line dropped from this point a i to the x-axis is the x-axis and the point b i+1They intersect at point b. i+1 is y=f i+1 This is the point where (x) intersects the x-axis.

[0044] Furthermore, among the multiple concave mirrors M shown in Figure 6, concave mirror M0 has no inner circumference, while the other concave mirrors M i The inner circumference of (i≧1) has a y-coordinate of 0.

[0045] As mentioned above, y=f i (x) is point a i (x i Since it passes through t), substitute this into equation (2) and x i to p,y i Expressed in terms of t, we get the following equation (3).

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[0049]

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[0050] As explained above, the four inspection devices 1 provided in the inspection system 9 have a composite mirror 11 in which multiple concave mirrors M with different focal lengths are arranged so that the optical axis I and the focal point P overlap. In the example shown in Figure 6, the thickness t along the optical axis I is thinner than p, but when electromagnetic waves parallel to the optical axis I are received, they can be focused at the focal point P regardless of their x-coordinate. Therefore, the inspection device 1 according to the present invention is smaller than the inspection device 1 without the composite mirror 11.

[0051] The configurations, shapes, sizes, and arrangements described in the above embodiments are merely schematic representations to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the described embodiments and can be modified in various forms as long as it does not deviate from the scope of the technical idea set forth in the claims.

[0052] <Variation> The above describes the embodiment, but the contents of this embodiment can be modified as follows. Furthermore, the following modifications may be combined.

[0053] <1> In the embodiment described above, the optical system 12 was a parabolic mirror that collimated the electromagnetic waves collected by the composite mirror 11 and guided them to the detector 13, but other configurations are also possible. For example, the optical system 12 may be a polygonal mirror.

[0054] Figure 7 shows an example of an inspection device 1 using a polygon mirror in the optical system 12. The optical system 12 shown in Figure 7 is, for example, a square pyramidal polygon mirror, which rotates around axis J to scan the composite mirror 11 in the Z-axis direction (x-axis direction). Electromagnetic waves reflected by the composite mirror 11 are further reflected by the optical system 12, and then further reflected by the parabolic mirror 14 before being guided to the detector 13.

[0055] <2> In the embodiment described above, the composite mirror 11 was configured so that there were no gaps when viewed from the y-axis direction, but it is sufficient if there are no gaps when viewed from the focal point P.

[0056] Figure 8 shows an example of a composite mirror 11 with no gaps when viewed from the focal point P. In the composite mirror 11 shown in Figure 8, the point where a line drawn from the focal point P to a point on the outer circumference of the concave mirror M intersects with the x-axis in the xy-plane is a point on the inner circumference of the concave mirror M that is positioned outside of that concave mirror M. Even with this configuration, electromagnetic waves traveling in the -y direction are reflected by the multiple concave mirrors M and collected at the focal point P. And since there are no gaps in the composite mirror 11 when viewed from the focal point P, the collected electromagnetic waves do not disperse.

[0057] <3> In the embodiment described above, the curved shapes of the multiple concave mirrors M are functions f0(x), f1(x), ..., f that are different from each other in the xy-plane. i (x), f i+1 (x), ... were determined by these, but they may also be determined by a common function f(x).

[0058] Figure 9 shows an example of the shapes of multiple concave mirrors M that can be represented by a single function. The multiple concave mirrors M shown in Figure 9 have shapes obtained by cutting a single function f(x) along the y-axis at intervals of t. All of these multiple concave mirrors M are arranged in a manner that has been translated so that their lower ends are tangent to the x-axis.

[0059] In this case, each of the multiple concave mirrors M reflects the electromagnetic wave incident in the -y direction at its inner circumference, directing it to the focal point P(0,p), and also reflects it at its outer circumference, directing it to the point Pt(0,p+t).

[0060] For example, among the composite mirrors 11, the x-coordinate is x i The point is, concave mirror M i On the outer periphery and the concave mirror M i+1 They lie on the inner circumference. The inclination of each of these points in the concave mirror M is such that the x-coordinate on y=f(x) described above is x i This coincides with the slope of the tangent line T at the points. Therefore, electromagnetic waves incident in the -y direction at these points are reflected in the direction reflected by the plane mirror positioned along the tangent line T.

[0061] The normal vector N is the vector whose x-coordinate is x i At this point, the line is perpendicular to the tangent line T. The angle of incidence and the angle of reflection shown in Figure 9 are equal, and both are angles Φ. The complementary angle of twice the angle Φ is the angle θ between the x-axis and the reflection direction described above. Therefore, the relationship between angle Φ and angle θ is expressed by the following equation (7).

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[0065]

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[0066]

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[0067] In this case, even if the composite mirror 11 has a thickness of t, when it receives electromagnetic waves radiated in the -y direction, it can collect them between focal points P and Pt, regardless of their x-coordinate. [Explanation of Symbols]

[0068] 1...Inspection device, 11...Composite mirror, 12...Optical system, 13...Detector, 14...Parabolic mirror, 9...Inspection system.

Claims

1. An inspection device that examines a person's belongings based on electromagnetic waves collected by multiple concave mirrors with different focal lengths, arranged in an xyz coordinate space, where the optical axis coincides with the y-axis, the x-coordinate of the focal point is 0, the y-coordinate is p, and the mirrors occupy the range from 0 to t (where 0 < t < p) in the y-axis direction.

2. The concave mirror is a parabolic mirror. The inspection apparatus according to claim 1.

3. The aforementioned plurality of concave mirrors are arranged so as not to obstruct the movement of people. The inspection apparatus according to claim 1 or 2.

4. The plurality of concave mirrors are arranged without gaps when viewed from a direction along the optical axis. The inspection apparatus according to any one of claims 1 to 3.

5. The plurality of concave mirrors are arranged without gaps when viewed from the focal point. The inspection apparatus according to any one of claims 1 to 3.

6. The optical system positioned at the aforementioned focal point guides the electromagnetic waves collected by the multiple concave mirrors to the detector. The inspection apparatus according to any one of claims 1 to 5.

7. The optical system is a polygon mirror. The inspection apparatus according to claim 6.

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