Imaging apparatus and inspection system

Abstract

An imaging apparatus according to the present invention comprises a lens unit and an image sensor, wherein light from an imaging target is guided by the lens unit to the image sensor. The imaging apparatus further comprises: a slit that extends in a first direction and allows light incident from the imaging target to pass through; and a plurality of mirror units that extend in the first direction and guide the light incident through the slit to the lens unit while reflecting the light. When viewed in the first direction, the lens unit and the plurality of mirror units are arranged such that the direction in which the path of the light incident through the slit extends and the direction in which the path of the light transmitted through the lens unit extends are parallel to a second direction different from the first direction.

Description

Imaging device and inspection system

[0001] This invention primarily relates to an imaging device.

[0002] Patent documents 1 and 2 disclose an imaging device configuration in which light from an object to be imaged is guided to an image sensor by a lens unit to perform imaging. Such an imaging device can be applied, for example, to inspection systems, evaluation systems, etc.

[0003] Patent No. 7057663 Patent No. 4251312

[0004] In the configurations described in Patent Documents 1 and 2, multiple mirror units are arranged in the optical path from the imaging target to the lens unit, and depending on their arrangement, this can lead to an increase in the size of the imaging device. Generally, miniaturizing imaging devices is one of the challenges in this field.

[0005] The present invention aims to further miniaturize imaging devices.

[0006] One aspect of the present invention relates to an imaging device, the imaging device comprising a lens unit and an image sensor, the imaging device which guides light from an object to be imaged to the image sensor by the lens unit, further comprising: a slit extending in a first direction and into which light from the object to be imaged can be incident; and a plurality of mirror units extending in the first direction and guiding the incident light from the slit to the lens unit while reflecting it, characterized in that, when viewed in the first direction, the lens unit and the plurality of mirror units are arranged such that the direction in which the path of light incident on the slit extends and the direction in which the path of light that has passed through the lens unit extends are parallel to a second direction different from the first direction.

[0007] According to the present invention, it becomes possible to further miniaturize the imaging device.

[0008] This figure shows the configuration of the imaging device and inspection system according to the embodiment. This is a cross-sectional perspective view showing the cross-sectional structure of the imaging device. This is a schematic side view showing an example of the internal structure of the imaging device. This is a schematic top view showing an example of the internal structure of the imaging device. This is a schematic side view showing another example of the internal structure of the imaging device.

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential for the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are given the same reference numerals, and duplicate descriptions are omitted.

[0010] <<First Embodiment>> <Regarding the inspection system> FIG. 1A is a diagram showing the configuration of the imaging device 1 and the inspection system SY according to the embodiment. FIG. 1B is a cross-sectional perspective view showing the cross-sectional structure of the imaging device 1. The imaging device 1 can be applied to the inspection system SY together with the transport device 2 and the lighting device 3. The transport device 2 transports the imaging object OB, thereby causing the imaging object OB to be scanned with respect to a slit 101 (see FIG. 2) described later. The lighting device 3 is arranged on the side of the imaging device 1 and irradiates the imaging object OB with light. In the present embodiment, a pair of lighting devices 3 are arranged on both sides of the imaging device 1, and they are arranged to have symmetry with respect to the slit 101. More specifically, the pair of lighting devices 3 are fixed at positions equidistant from the slit 101 in a posture in which their irradiation directions both face downward of the slit 101. The reflected light from the irradiated imaging object OB enters the imaging device 1 through the slit 101, and based on this, the imaging device 1 performs imaging.

[0011] Regarding the imaging result obtained by the imaging device 1, image analysis is performed by an image analysis device (not shown). For example, it is possible to determine whether the imaging object OB satisfies a predetermined standard. The inspection system SY may be expressed as an evaluation system or the like.

[0012] Here, the same shall apply to other figures described later. In the figures, for ease of understanding of the structure, the X direction, Y direction, and Z direction that intersect (substantially orthogonal) with each other are shown. The X direction corresponds to the front-back direction or the depth direction, the Y direction corresponds to the left-right direction or the width direction, and the Z direction corresponds to the up-down direction or the height direction. Note that the pair of lighting devices 3 are arranged side by side in the Y direction, and the transport device 2 transports the imaging object OB in the Y direction.

[0013] In the following description, for each of the X, Y, and Z directions, one side and the other side may be indicated by the signs "+" and "-" respectively (for example, the left side may be expressed as the -Y side and the right side may be expressed as the +Y side). However, when such distinction is not particularly required, the notation of the signs is omitted.

[0014] <Internal Structure of Imaging Device> Figure 2 is a side schematic view (viewed in the -X direction / schematic side view) showing an example of the internal structure of the imaging device 1. As shown in FIGS. 1A, 1B, and 2, the imaging device 1 includes a housing 10, a lens unit 11, an image sensor 12, and a plurality of mirror units 13.

[0015] The housing 10 incorporates the lens unit 11, the image sensor 12, and the plurality of mirror units 13, and each of them is fixed directly or indirectly (via a predetermined member) to the inner wall of the housing 10. Further, a slit 101 is provided at substantially the center of the surface of the housing 10 on the imaging target OB side (i.e., the -Z side). The slit 101 extends in the X direction and allows light from the imaging target OB to be incident.

[0016] The lens unit 11 incorporates one or more lenses arranged such that its optical axis is parallel to the Z direction. Although details will be described later, the lens unit 11 condenses the light from the imaging target OB guided while being reflected by the plurality of mirror units 13 and guides it to the image sensor 12.

[0017] The image sensor 12 is a line sensor in which a plurality of photoelectric conversion elements 121 are arranged in the X direction and can detect the light that has passed through the lens unit 11. In the present embodiment, the image sensor 12 is arranged in a horizontal posture. The light detected by the image sensor 12 is transferred as pixel signals to an image generation device (not shown) capable of generating image data. The aforementioned image analysis can be performed based on this image data.

[0018] The plurality of mirror units 13 are bar-shaped members each extending in the X direction and having a light reflecting surface, and are arranged in the housing 10 so as to be able to form an optical path (path of light) corresponding to the focal length of the lens unit 11. In the present embodiment, five mirror units 13 １ ~13 ５ are arranged, but in the following description, they are simply referred to as mirror units 13 when there is no particular need to distinguish them.

[0019] In the figure, for the sake of easy understanding, for the light passing through the center of the light beam from the imaging object OB to the image sensor 12, that is, the light that should pass through the optical axis of the lens unit 11, the optical paths L0 to L6 from the imaging object OB to the image sensor 12 are shown. The optical path L0 indicates the optical path from the imaging object OB to the mirror unit 13 １ The optical path L1 indicates the optical path from the mirror unit 13 １ to the mirror unit 13 ２ The optical path L2 indicates the optical path from the mirror unit 13 ２ to the mirror unit 13 ３ The optical path L3 indicates the optical path from the mirror unit 13 ３ to the mirror unit 13 ４ The optical path L4 indicates the optical path from the mirror unit 13 ４ to the mirror unit 13 ５ The optical path L5 indicates the optical path from the mirror unit 13 ５ to the lens unit 11. Also, the optical path L6 indicates the optical path from the lens unit 11 to the image sensor 12.

[0020] FIG. 3 is a top schematic view (viewed from the -Z direction / schematic view in plan view) showing the positional relationship of the lens unit 11, the image sensor 12, and the plurality of mirror units 13 in the housing 10. The lens unit 11 and the image sensor 12 are fixed above the substantially central portion of the mirror unit 13 ５ extending in the X direction.

[0021] With this configuration, light entering the housing 10 from the imaging target OB through the slit 101 is reflected by multiple mirror units 13 and then guided to the image sensor 12 via the lens unit 11, making it detectable.

[0022] <Regarding the arrangement of each element within the imaging device> In order to form an optical path corresponding to the focal length of the lens unit 11, multiple mirror units 13 are required, and their arrangement within the housing 10 may result in the imaging device 1 becoming larger. Furthermore, it is desirable to suppress the number of mirror units 13 (number of reflections) to prevent unnecessary light scattering, but in order to secure an optical path corresponding to the focal length of the lens unit 11, the imaging device 1 may become larger. For this reason, there is a general demand for technologies that are advantageous for miniaturizing such imaging devices 1.

[0023] In this embodiment, the multiple mirror units 13 are arranged towards the -Y side and / or -Z side within the housing 10, and the lens unit 11 is arranged towards the +Y side and +Z side within the housing 10. More specifically, as shown in Figure 2: Mirror unit 13 １ The mirror unit 13 is located on the -Z side of the housing 10, on the +Z side of the slit 101 and on the -Z side of the lens unit 11, and is fixed in a position that allows it to reflect light from the imaging target OB to the -Y side; ２ The mirror unit 13 is located on the -Y side and -Z side within the housing 10. １ The mirror unit 13 is fixed in a position that allows it to reflect the reflected light from the mirror to the +Z side. ３ The mirror unit 13 is located on the -Y side and +Z side within the housing 10. ２ The mirror unit 13 is fixed in a position that allows it to reflect the reflected light from the mirror to the -Z side. ４ The mirror unit 13 is located on the -Y side and -Z side within the housing 10. ２ It is located on the +Y side and the +Z side, and the mirror unit 13 ３ It is fixed in a position that allows reflected light from to be reflected to the +Y side; also, the mirror unit 13 ５ The mirror unit 13 is located on the -Z side within the housing 10.１ It is located on the +Z side of the mirror unit 13 and on the -Z side of the lens unit 11. ４ It is fixed in a position that allows reflected light to be reflected towards the +Z side.

[0024] With this arrangement, light incident from the imaging target OB in the +Z direction is directed to the mirror unit 13 １ This is reflected to the -Y side by the mirror unit 13 ２ This is reflected further to the +Z side, by the mirror unit 13 ３ This is reflected to the -Z side, and the mirror unit 13 ４ This is then reflected further to the +Y side, and then the mirror unit 13 ５ The light is reflected in the +Z direction and guided to the lens unit 11. In this way, it is possible to improve the efficiency of the arrangement of each element within the housing 10 while forming an optical path corresponding to the focal length of the lens unit 11.

[0025] In this embodiment, the lens unit 11 and the multiple mirror units 13 are arranged such that the directions in which the optical paths L0 and L6 extend are both parallel to the Z direction, and the optical axis of the lens unit 11 and the optical path passing through the slit 101 to pass through the optical axis are parallel to the Z direction. With this configuration, the above arrangement can be realized for the multiple mirror units 13, and further miniaturization of the imaging device 1 in the Y direction becomes possible.

[0026] Furthermore, the lens unit 11 is positioned towards the +Y and +Z sides within the housing 10, and is located on the +Y side relative to the slit 101. In this configuration, the mirror unit 13 reflects light toward the lens unit 11. ５ Although one mirror unit is positioned on the +Y side, the other mirror units 13 are positioned on the -Y side.

[0027] Since the lens unit 11 is positioned towards the +Y and +Z sides within the housing 10, the slit 101, which is located approximately in the center of the surface of the housing 10 on the imaging target OB side, is not located on the optical axis of the lens unit 11. In this embodiment, one end of the slit 101 (the +Y side end) is located in the Y direction, relative to the mirror unit 13 １It is located between the center of the mirror unit 13 and the center of the lens unit 11. １ The center of the lens unit 11 also refers to the center of the outer shape in the Y direction when viewed from the side.

[0028] Because the slit 101 is not located on the optical axis of the lens unit 11, the reflected light from the imaging target OB is not directed towards the mirror unit 13. １ This prevents stray light components that were not reflected from directly entering the lens unit 101 or from being diffusely reflected inside the lens unit 101, thereby preventing adverse effects on the imaging results. Furthermore, it eliminates the need to install an aperture on the light-receiving side of the lens unit 11.

[0029] In addition, in this embodiment, the mirror unit 13 ３ This mirror unit 13 is positioned on the +Z side and closer to the image sensor 12 than the other mirror units 13, resulting in relatively longer optical paths L2 and L3. ２ and mirror unit 13 ４ Mirror unit 13 from each ３ The distance is greater than at least half the size of the lens unit 11 in the Z direction, and in this embodiment, greater than the entire size of the lens unit 11 in the Z direction. Mirror unit 13 ３ It may be positioned higher than the image sensor 12, lower than the image sensor 12, or at approximately the same height as the image sensor 12.

[0030] Mirror unit 13 ３ The reflective surface is facing the direction of the imaging target OB. Therefore, of the reflected light from the imaging target OB, the mirror unit 13 １ The stray light components that were not reflected are reflected by the mirror unit 13 ３ The light may reach the surface and reflect, potentially causing diffuse reflection within the housing 10 and negatively affecting the imaging results. In particular, the mirror unit 13 near the light-receiving surface of the lens unit 11 ３If the above-mentioned diffuse reflection occurs, it is thought that stray light components will enter the lens unit 11, and the adverse effect on the imaging result will become more pronounced. However, according to this embodiment, the mirror unit 13 ３ By positioning the lens slit 101 at a distance from the lens slit 101 and at a distance from the light-receiving surface of the lens unit 11, the aforementioned diffuse reflection can be prevented, thereby improving the quality of the imaging results. Furthermore, by utilizing the space adjacent to the lens unit 11, which has a large dimension in the Z direction, it becomes possible to secure a long optical path in the Z direction. In other words, it becomes possible to secure a long optical path within the housing 10 while keeping the size of the housing 10 down.

[0031] Mirror unit 13 ３ In the Y direction, the mirror unit 13 ２ and mirror unit 13 ４ It is located between and the mirror unit 13 ２ Light from the mirror unit 13 ４ The light is reflected at an acute angle toward the direction. Here, the angle between optical path L2 and optical path L3 is denoted as angle θ (θ < 90°). In order to suppress the increase in size of the imaging device 1 in the Y direction, angle θ should be set within the range of 2 to 14°, for example. Similarly, the angle between optical path L2 and the Z direction, and the angle between optical path L3 and the Z direction should both be set within the range of 1 to 7°.

[0032] In this configuration, the mirror unit 13 １ and mirror unit 13 ３ The distance to is greater than the distance between other mirror units 13, and the mirror unit 13 １ and mirror unit 13 ５ The distance to this point is smaller than the distance between the other mirror units 13.

[0033] Furthermore, by arranging the multiple mirror units 13 so that their light-reflecting surfaces are not parallel to each other and their optical paths L0 to L6 do not intersect, it becomes easier to adjust the attitude / orientation of each individual mirror unit 13. This is advantageous in simplifying the design of optical systems, which can be relatively complex.

[0034] In this embodiment, the mirror unit 13 ３ An example was given in which the mirror units 13 are spaced apart in the Z direction from other mirror units 13. However, the arrangement of the mirror units 13 is not limited to this example, and it is sufficient that at least one of the multiple mirror units 13 is spaced apart in the Z direction from other mirror units 13.

[0035] Furthermore, although the number of mirror units 13 was set to 5 in the above example, the content of this embodiment is not limited to this example, and can be applied to other quantities of mirror units 13. For example, let the number of mirror units 13 be N (the example in this embodiment shows the case where N = 5). In this case, for example, mirror unit 13 ３ Regarding the above-described arrangement, if K is an integer greater than 1 and less than N, then the Kth mirror unit can be said to be positioned spaced apart in the Z direction from the (K-1)th mirror unit and the (K+1)th mirror unit. Here, the (K-1)th mirror unit corresponds to a mirror unit that reflects light toward the Kth mirror unit, and the (K+1)th mirror unit corresponds to another mirror unit that reflects light from the Kth mirror unit. Furthermore, in order to suppress the number of mirror units 13, it is preferable to keep the value of N to a minimum.

[0036] In the above description, an example was given in which reflected light from the imaging target OB is detected by the optical system inside the housing 10. However, the reflected light referred to here may be reflected light due to diffuse reflection or reflected light due to total internal reflection. Furthermore, the imaging target OB may be a transparent material, and the concept of light from the imaging target OB may include transmitted light that has passed through the imaging target OB. Examples of the imaging target OB in this case include light-transmitting materials that allow light from illumination to pass through, such as film materials, sheet materials, etc.

[0037] ≪Second Embodiment≫ Figure 4 is a schematic side view showing an example of the internal structure of the imaging device 1 according to the second embodiment. In the first embodiment described above, the image sensor 12 was arranged in a horizontal position within the housing 10, whereas in this embodiment, the image sensor 12 is arranged in a vertical position. In this embodiment, a mirror unit 13 reflects the light that has passed through the lens unit 11 toward the image sensor 12. ６ Further arrangements are made.

[0038] In the diagram, the optical path L6 (see Figure 2) mentioned above is replaced by the path from lens unit 11 to mirror unit 13. ６ The optical path L6' to the mirror unit 13 ６ The optical path L6'' from the image sensor 12 is shown. In this embodiment, the lens unit 11 and the multiple mirror units 13 should be arranged so that the optical path L0 and the optical path L6'' are parallel to the Z direction.

[0039] According to this embodiment, for example, if the image sensor 12 is wide (in the first embodiment, the size in the Y direction is large), the size of the imaging device 1 in the Y direction can be suppressed by arranging such an image sensor 12 in a vertical position.

[0040] In the above explanation, for the sake of ease of understanding, each element has been given a name related to its function. However, each element is not limited to having the content described in the embodiment as its primary function, but may also have it as a secondary function. Therefore, each element is not strictly limited to its expression, and its expression can be replaced with other similar expressions. In the same vein, the expression "apparatus" may be replaced with "unit," "component, piece," "member," "structure," "assembly," etc., or it may be omitted or added.

[0041] ≪Summary of Embodiments≫ Some of the features illustrated in the above embodiments are as follows: [Item 1] An imaging device (1) comprising a lens unit (11) and an image sensor (12), wherein the lens unit guides light from an object to be imaged (OB) to the image sensor, further comprising: a slit (101) extending in a first direction (X direction) into which light from the object to be imaged can be incident; and a plurality of mirror units (13) extending in the first direction and guiding the incident light from the slit to the lens unit while reflecting it, wherein when viewed in the first direction, the lens unit and the plurality of mirror units are arranged such that the direction in which the path of light incident in the slit extends and the direction in which the path of light that has passed through the lens unit extends are parallel to a second direction (Z direction) different from the first direction. [Item 2] The imaging device according to Item 1, wherein when viewed in the first direction, the slit is not located on the optical axis of the lens unit. [Item 3] The imaging apparatus according to item 1 or item 2, characterized in that the first direction and the second direction are orthogonal. [Item 4] Of the plurality of mirror units, one that reflects the light incident on the slit is the first mirror unit (13 １ The imaging apparatus according to item 3, characterized in that, when viewed in the first direction, one end of the slit is located between the center of the first mirror unit and the center of the lens unit in a third direction (Y direction) perpendicular to both the first and second directions. [Item 5] When viewed in the first direction, at least one of the plurality of mirror units (13 ３ The imaging apparatus according to item 3 or item 4, characterized in that one of the plurality of mirror units is positioned spaced apart from the other mirror units in the second direction. [Item 6] One of the plurality of mirror units is the Kth mirror unit (13 ３ ) and the other one that reflects light toward the mirror unit K is the (K-1) mirror unit (13 ２ ) and the other one that reflects light from the aforementioned mirror unit K is the (K+1) mirror unit (13 ４The imaging apparatus according to any one of items 3 to 5, characterized in that, when viewed in the first direction, the mirror unit K is spaced apart in the second direction from the mirror unit (K-1) and the mirror unit (K+1). [Item 7] The imaging apparatus according to item 6, characterized in that, when viewed in the first direction, the distance of the mirror unit K from the mirror unit (K-1) and the mirror unit (K+1) is greater than half the size of the lens unit in the second direction. [Item 8] The imaging apparatus according to item 6 or 7, characterized in that the mirror unit K is spaced closer to the image sensor than the other mirror units. [Item 9] The imaging apparatus according to any one of items 6 to 8, characterized in that, when viewed in the first direction, the mirror unit K is located between the mirror unit (K-1) and the mirror unit (K+1) in a third direction (Y direction) that is orthogonal to both the first and second directions. [Item 10] The imaging device according to any one of items 6 to 9, characterized in that, when viewed in the first direction, the angle formed by the optical path (L2) from the (K-1) mirror unit to the K mirror unit and the optical path (L3) from the K mirror unit to the (K+1) mirror unit is within the range of 2 to 14°. [Item 11] The imaging device according to item 10, characterized in that, when viewed in the first direction, the angle formed by the optical path (L2) from the (K-1) mirror unit to the K mirror unit and the second direction is within the range of 1 to 7°, and the angle formed by the optical path (L3) from the K mirror unit to the (K+1) mirror unit and the second direction is within the range of 1 to 7°. [Item 12] The imaging device according to item 10, characterized in that, when viewed in the first direction, the first mirror unit (13) that reflects the light incident on the slit. １ ) and the mirror unit of K (13 ３An imaging apparatus according to any one of items 6 to 11, characterized in that the distance to the first mirror unit (13) is greater than the distance between other mirror units. [Item 13] Let the number of the plurality of mirror units be N, and when viewed in the first direction, the first mirror unit (13) that reflects the light incident on the slit. １ ) and a nth mirror unit (13) that reflects light toward the lens unit. ５ An imaging device according to any one of items 6 to 12, characterized in that the distance to the first mirror unit (13) is smaller than the distance between other mirror units. [Item 14] An imaging device according to item 13, characterized in that when viewed in the first direction, the first mirror unit and the N mirror unit are located between the slit and the lens unit in the second direction. [Item 15] An imaging device according to any one of items 1 to 14, characterized in that when viewed in the first direction, the lens unit is located on the first side (+Y side) with respect to the slit, and at least a portion of the plurality of mirror units are located on the second side (-Y side) opposite to the first side with respect to the slit. [Item 16] When viewed in the first direction, one of the plurality of mirror units (13) reflects light toward the lens unit. ５[Item 17] The imaging device according to item 15, characterized in that the lens unit is located on the first side. [Item 18] The imaging device according to item 17, characterized in that, when viewed in the first direction, the plurality of mirror units are arranged such that the paths of light reflected between them do not intersect with each other. [Item 19] The imaging device according to item 1 to 18, characterized in that, when viewed in the first direction, the plurality of mirror units are arranged such that their light-reflecting surfaces are not parallel to each other. [Item 21] The inspection system according to Item 20, characterized in that, when viewed in the first direction, the irradiation devices are arranged in a pair on both sides of the imaging device, and the pair of irradiation devices are positioned symmetrically with respect to the slit. [Item 22] An inspection system (SY) characterized by comprising: an imaging device (1) according to any one of Items 1 to 19; and a transport device (2) for transporting the object to be imaged relative to the imaging device.

[0042] The invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention.

Claims

1. An imaging device comprising a lens unit and an image sensor, wherein the lens unit guides light from an object to be imaged to the image sensor, further comprising: a slit extending in a first direction and into which light from the object to be imaged can be incident; and a plurality of mirror units extending in the first direction and guiding the incident light from the slit to the lens unit while reflecting it, wherein, when viewed in the first direction, the lens unit and the plurality of mirror units are arranged such that the direction in which the path of light incident on the slit extends and the direction in which the path of light that has passed through the lens unit extends are parallel to a second direction different from the first direction.

2. The imaging apparatus according to claim 1, characterized in that, when viewed in the first direction, the slit is not located on the optical axis of the lens unit.

3. The imaging apparatus according to claim 1 or 2, characterized in that the first direction and the second direction are orthogonal to each other.

4. The imaging apparatus according to claim 3, wherein, of the plurality of mirror units, one that reflects light incident on the slit is designated as the first mirror unit, and when viewed in the first direction, one end of the slit is located between the center of the first mirror unit and the center of the lens unit in a third direction perpendicular to both the first and second directions.

5. The imaging apparatus according to claim 3 or 4, characterized in that, when viewed in the first direction, at least one of the plurality of mirror units is spaced apart from the other mirror units in the second direction.

6. The imaging apparatus according to any one of claims 3 to 5, wherein one of the plurality of mirror units is designated as the Kth mirror unit, another one that reflects light toward the Kth mirror unit is designated as the (K-1)th mirror unit, and another one that reflects light from the Kth mirror unit is designated as the (K+1)th mirror unit, and when viewed in the first direction, the Kth mirror unit is positioned spaced apart from the (K-1)th mirror unit and the (K+1)th mirror unit in the second direction.

7. The imaging apparatus according to claim 6, characterized in that, when viewed in the first direction, the distance of the mirror unit K from the (K-1) mirror unit and the (K+1) mirror unit, respectively, is greater than half the size of the lens unit in the second direction.

8. The imaging apparatus according to claim 6 or 7, characterized in that the mirror unit K is positioned closer to the image sensor than the other mirror units.

9. The imaging apparatus according to any one of claims 6 to 8, characterized in that, when viewed in the first direction, the mirror unit K is located between the mirror unit (K-1) and the mirror unit (K+1) in a third direction perpendicular to both the first and second directions.

10. The imaging apparatus according to any one of claims 6 to 9, characterized in that, when viewed in the first direction, the angle formed by the optical path from the (K-1) mirror unit to the K mirror unit and the optical path from the K mirror unit to the (K+1) mirror unit with respect to light that should pass through the optical axis of the lens unit is within the range of 2 to 14°.

11. The imaging apparatus according to claim 10, characterized in that, when viewed in the first direction, with respect to light that should pass through the optical axis of the lens unit, the angle formed between the optical path from the (K-1) mirror unit to the K mirror unit and the second direction is in the range of 1 to 7°, and the angle formed between the optical path from the K mirror unit to the (K+1) mirror unit and the second direction is in the range of 1 to 7°.

12. The imaging apparatus according to any one of claims 6 to 11, characterized in that, when viewed in the first direction, the distance between the first mirror unit that reflects light incident on the slit and the mirror unit K is greater than the distance between the other mirror units.

13. The imaging apparatus according to any one of claims 6 to 12, wherein, with N being the number of the plurality of mirror units, when viewed in the first direction, the distance between the first mirror unit that reflects light incident on the slit and the Nth mirror unit that reflects light toward the lens unit is smaller than the distance between the other mirror units.

14. The imaging apparatus according to claim 13, characterized in that, when viewed in the first direction, the first mirror unit and the N mirror unit are located between the slit and the lens unit in the second direction.

15. The imaging apparatus according to any one of claims 1 to 14, characterized in that, when viewed in the first direction, the lens unit is positioned on the first side with respect to the slit, and at least a portion of the plurality of mirror units is positioned on the second side opposite to the first side with respect to the slit.

16. The imaging apparatus according to claim 15, characterized in that, when viewed in the first direction, one of the plurality of mirror units that reflects light toward the lens unit is located on the first side.

17. The imaging apparatus according to any one of claims 1 to 16, characterized in that, when viewed in the first direction, the plurality of mirror units are arranged such that the paths of light reflected between them do not intersect with each other.

18. The imaging apparatus according to claim 17, characterized in that, when viewed in the first direction, the plurality of mirror units are arranged so that their light-reflecting surfaces are not parallel to each other.

19. The imaging apparatus according to any one of claims 1 to 18, further comprising a housing that houses the lens unit, the image sensor, and the plurality of mirror units, and wherein the slit is provided in the center of the side of the surface facing the object to be imaged when viewed in the first direction.

20. An inspection system comprising: an imaging device according to any one of claims 1 to 19; and an illumination device positioned to the side of the imaging device when viewed in the first direction.

21. The inspection system according to claim 20, characterized in that, when viewed in the first direction, the irradiation devices are arranged in a pair on both sides of the imaging device, and the pair of irradiation devices are positioned symmetrically with respect to the slit.

22. An inspection system comprising: an imaging device according to any one of claims 1 to 19; and a transport device for transporting the object to be imaged relative to the imaging device.

Images