WO2019230215A1

WO2019230215A1 - Image capture device

Info

Publication number: WO2019230215A1
Application number: PCT/JP2019/016081
Authority: WO
Inventors: 祥雄古谷
Original assignee: 株式会社Ｓｃｒｅｅｎホールディングス
Priority date: 2018-05-30
Filing date: 2019-04-15
Publication date: 2019-12-05
Also published as: JP6966974B2; JP2019207188A; TW202004320A; TWI686660B

Abstract

In order to excellently capture an image of the inner circumferential surface of a hole in a short time, the present invention is provided with: a light source that emits illumination light for illuminating the inner circumferential surface of a hole that is formed in a hole forming direction from a surface of an image-capture subject; a head part that has a plurality of folding mirrors, and that rotates about a rotation axis parallel with the hole forming direction in a state of being inserted in the hole such that the plurality of folding mirrors guide the illumination light to regions, of the inner circumferential surface, different with respect to the hole forming direction and reflection light beams having been reflected by the regions are taken out from the hole; an image rotation correcting unit that keeps the orientation of an image captured by an image capture unit constant, by guiding, toward the image capture unit, a plurality of the reflection light beams taken out by the head part, while rotating about the rotation axis such that the rotation angle of the image rotation correcting unit per unit time becomes equal to one half of the rotation angle of the head part; and an optical path length difference correcting unit that guides the reflection light beams emitted from the image rotation correcting unit to the image capture unit while adjusting, for each of the reflection light beams, the optical length of the reflection light beam from the image rotation correcting unit to the image-capture unit according to the optical length difference among the plurality of reflection light beams in the head part.

Description

Imaging device

The present invention relates to an imaging device that images an inner peripheral surface of a hole formed in a hole forming direction from the surface of an imaging object.
The disclosures in the following specification, drawings, and claims of the Japanese application are incorporated herein by reference in their entirety:
Japanese Patent Application No. 2018-103494 (filed on May 30, 2018).

As one of three-dimensional workpieces such as metal parts, resin parts, and rubber parts, there are those in which holes (including recesses and through holes) are provided from the surface of the work. For example, when a cylindrical hole is formed by cutting on the surface of a disk-shaped metal plate, it is necessary to inspect whether or not the inner peripheral surface of the hole is formed in a desired peripheral surface state. Therefore, for example, an inspection technique has been proposed in which an inner peripheral surface of a hole is imaged using an imaging device described in Patent Document 1 and a workpiece is inspected based on an image obtained by the imaging device.

JP 2012-49624 A

In the imaging apparatus described in Patent Document 1, a lens barrel that can be inserted into and removed from a hole of a workpiece is extended in the vertical direction. An objective mirror is disposed on the lower end side of the lens barrel at an angle of 45 ° with respect to the axis of the lens barrel, and the illumination light directed downward from above along the axis of the lens barrel is folded back in the horizontal direction. Irradiate the inner peripheral surface of the hole. The reflected light reflected by the inner peripheral surface of the hole is folded upward by the objective mirror and received by the camera unit via the light control unit. Thereby, the partial image of the inner peripheral surface of the hole is taken by the camera unit.

In this imaging apparatus, the lens barrel and the objective mirror are rotated around the axis in order to image the inner peripheral surface of the hole over the entire circumference. Further, since the reflected light emitted from the lens barrel rotates around the axis along with the rotation, the dimmer is rotated around the axis. By adopting such a configuration, the light incident on the camera unit is prevented from rotating around the axis, and the orientation of the image captured by the camera unit is maintained constant. In this way, it is possible to satisfactorily capture an entire peripheral image of the inner peripheral surface of the hole at the insertion height position of the lens barrel and the objective mirror.

However, in order to capture an image of the entire circumference of the inner surface of a hole that is sufficiently deep compared to the size of the objective mirror in the vertical direction, each insertion is performed while switching the insertion height position of the lens barrel and objective mirror in multiple stages. It is necessary to rotate the lens barrel and the objective mirror at the height position and to repeatedly capture the entire circumference image by the camera unit while rotating the light control unit in synchronization with the rotation. Therefore, it may take a long time to image the inner peripheral surface of the hole.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging device capable of imaging the inner peripheral surface of a hole satisfactorily in a short time.

An image pickup apparatus according to the present invention is an image pickup apparatus that picks up an image of an inner peripheral surface of a hole formed in a hole forming direction from a surface of an object to be imaged, and emits illumination light for illuminating the inner peripheral surface. Light source and a plurality of folding mirrors, and each of the plurality of folding mirrors guides the illumination light to different areas in the hole forming direction on the inner peripheral surface and extracts reflected light reflected by the areas from the holes A head portion that rotates around a rotation axis parallel to the hole forming direction while being inserted into the hole, and a head that rotates around the rotation axis so that the rotation angle per unit time is a half rotation angle of the head portion. An image rotation correction unit that guides a plurality of reflected lights extracted from the image pickup unit toward the image pickup unit and maintains the orientation of an image picked up by the image pickup unit, and each reflected light emitted from the image rotation correction unit From the image rotation correction unit to the imaging unit It is characterized in that it comprises an optical path length difference correcting unit for guiding to the imaging unit while adjusting in response to the optical path length difference of a plurality of reflected light in the head portion of the optical path length of the reflected light in.

In the invention configured as described above, a plurality of folding mirrors are provided in the head portion inserted into the hole, and the illumination light is guided to different areas in the hole forming direction on the inner peripheral surface and reflected by the areas. The reflected light is extracted from the hole. Then, each reflected light is guided to the imaging unit. For this reason, it is possible to image the inner peripheral surface of the hole in a plurality of regions different from each other in the hole forming direction at a time.

In addition, by providing a plurality of folding mirrors in the head unit as described above, an optical path length difference occurs between the plurality of reflected lights in the head unit, but the optical path length difference until the reflected light enters the imaging unit. The correction unit adjusts the optical path length of the reflected light from the image rotation correction unit to the imaging unit for each reflected light emitted from the image rotation correction unit. For this reason, the optical path length from the inner peripheral surface to the imaging unit is the same for any reflected light, and the inner peripheral surface of the hole can be imaged satisfactorily for each region.

As described above, the head portion is provided with a plurality of folding mirrors, and the optical path length difference of the reflected light at the head portion that occurs with the mirror is adjusted by the optical path length difference correction portion. Good imaging can be performed in a short time.
A plurality of constituent elements of each aspect of the present invention described above are not essential, and some or all of the effects described in the present specification are to be solved to solve part or all of the above-described problems. In order to achieve the above, it is possible to appropriately change, delete, replace with another new component, and partially delete the limited contents of some of the plurality of components. In order to solve part or all of the above-described problems or to achieve part or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the above-described other aspects of the present invention may be combined to form an independent form of the present invention.

It is a figure which shows one Embodiment of the imaging device which concerns on this invention. It is a figure which shows typically the head part, image rotation correction | amendment part, and optical path length difference correction | amendment part which are the main structures of the imaging device shown in FIG. It is a figure which shows typically the optical path by which the light reflected by the internal peripheral surface of the through-hole is guide | induced to an imaging part. It is a figure which shows the main structures of an imaging part. It is the top view which looked at the optical path length difference correction | amendment part, the image rotation correction | amendment part, and head part which were shown in FIG. 3 from the Z direction. It is the side view which looked at the optical path length difference correction | amendment part, image rotation correction | amendment part, and head part which were shown in FIG. 3 from the Y direction. It is the side view which looked at the optical path length difference correction | amendment part, the image rotation correction | amendment part, and head part which were shown in FIG. 3 from the X direction.

FIG. 1 is a diagram showing an embodiment of an imaging apparatus according to the present invention. FIG. 2 is a diagram schematically showing a head unit, an image rotation correction unit, and an optical path length difference correction unit, which are the main components of the imaging apparatus shown in FIG. FIG. 3 is a diagram schematically illustrating an optical path in which light reflected by the inner peripheral surface of the through hole, that is, reflected light is guided to the imaging unit. In this imaging apparatus 100, a workpiece 1 having a through hole 13 drilled from a front surface 11 to a rear surface 12 in the center of a disk-shaped metal plate is used as an imaging target, and the rear surface 12 of the workpiece 1 is held by a workpiece holding table 2. This is an apparatus for imaging the inner peripheral surface 14 of the through-hole 13 of the workpiece 1 in the state where the work is performed. In each of the following drawings, the hole forming direction in which the through hole 13 is formed is referred to as “Z direction”.

In the imaging apparatus 100, the head portion 3 is provided so as to be detachable from the (+ Z) direction with respect to the through hole 13 of the workpiece 1 held on the workpiece holding table 2. And when imaging the workpiece | work 1, the head part 3 is inserted in the through-hole 13 of the workpiece | work 1 as shown in FIG. 1 and FIG. An image rotation correction unit 4, an optical path length difference correction unit 5, and an imaging unit 6 are provided in this order above the head unit 3, that is, in the (+ Z) direction, and a light source 7 is provided on the side surface of the imaging unit 6. It is attached.

The light source 7 emits illumination light for illuminating the inner peripheral surface 14 of the through hole 13. As shown in FIG. 1, the illumination light IL emitted from the light source 7 is irradiated toward the half mirror 61 provided in the imaging unit 6. The illumination light IL is folded back in the (−Z) direction by the half mirror 61 and further enters the head unit 3 via the optical path length difference correction unit 5 and the image rotation correction unit 4. In the head unit 3, the illumination light IL is folded back in the (−X) direction and is applied to the inner peripheral surface 14 of the through hole 13.

On the other hand, the reflected light reflected by the inner peripheral surface 14 of the through hole 13 travels in the (+ X) direction, is folded back in the (+ Z) direction by the head portion 3, and is taken out from the through hole 13 of the workpiece 1. Then, the reflected light enters the imaging unit 6 through the image rotation correction unit 4 and the optical path length difference correction unit 5, passes through the half mirror 61, and is received by the imaging device 62. As a result, the imaging unit 6 images an area of the inner peripheral surface 14 of the through hole 13 that has been irradiated with the illumination light IL.

In the present embodiment, as shown in FIG. 2, the head unit 3 has two

folding mirrors

31 and 32. The

folding mirrors

31 and 32 are displaced from each other in the Z direction. More specifically, the folding mirror 32 is arranged so as to be shifted in the (−Z) direction from the folding mirror 31 and is located on the tip side in the Z direction. That is, the folding mirror 32 corresponds to an example of the “tip folding mirror” of the present invention. The folding mirror 32 is also displaced in the (−Y) direction from the folding mirror 31 in the Y direction orthogonal to the X direction and the Z direction. Therefore, as shown in FIG. 3, the illumination light IL (FIG. 1) is irradiated to the two regions R 1 and R 2 that are different from each other in the Z direction on the inner peripheral surface 14 through the folding mirrors 31 and 32, respectively. The reflected lights RL1 and RL2 reflected by the regions R1 and R2 are extracted from the through hole 13 via the folding mirrors 31 and 32, respectively. Of these reflected lights, the reflected light RL2 corresponds to an example of “tip reflected light” of the present invention.

In FIG. 3, symbol A1 indicates the reflection position of the illumination light IL in the region R1, and symbol A2 indicates the reflection position of the illumination light IL in the region R2. In FIG. 3, reference numeral B 1 is a folding position where the reflected light RL 1 is folded back by the mirror surface 311 of the folding mirror 31, and reference numeral B 2 is a folding position where the reflected light RL 2 is folded by the mirror surface 321 of the folding mirror 32. . In the present embodiment, the folding mirrors 31 and 32 are provided so that the surface normal of the mirror surface 311 is slightly inclined with respect to the surface normal of the mirror surface 312 and the reflected light RL2 is emitted in the Z direction. On the other hand, the reflected light RL1 travels gradually away from the reflected light RL2 in the Y direction (see FIG. 7). The reason will be described in detail later.

Further, in this way, the head portion 3 having the two folding mirrors 31 and 32 is configured such that the folding mirrors 31 and 32 are rotatable integrally with the central axis 13a of the through hole 13 extending parallel to the Z direction as a rotation axis. . The head unit 3 is mechanically connected to the head rotation driving unit 33 as shown in FIGS. For this reason, when the head rotation drive unit 33 is actuated in response to a rotation command from the control unit 9 that controls the entire apparatus, the head unit 3 rotates around the central axis 13a. As a result, the regions R1 and R2 move in the circumferential direction of the inner peripheral surface 14 to rotate the head portion 3 once, whereby the reflected lights RL1 and RL2 are extracted over the entire circumference of the inner peripheral surface 14 of the through hole 13.

When the head unit 3 is thus rotated, the reflected light RL1 and RL2 are also rotated according to the rotation. Therefore, also in the imaging apparatus 100 according to the present embodiment, the image rotation correction unit 4 having the same configuration as the light control unit of Patent Document 1 is provided. The image rotation correction unit 4 includes three correction mirrors 41 to 43, and the correction mirrors 41 to 43 are integrally rotatable with the central axis 13a of the through hole 13 as a rotation axis. The image rotation correction unit 4 is mechanically connected to the image rotation drive unit 44 as shown in FIGS. When the image rotation driving unit 44 is actuated in response to a rotation command from the control unit 9, the image rotation correction unit 4 rotates about the central axis 13a. However, the rotation is controlled so that the rotation speed, that is, the rotation angle θ per unit time becomes a half rotation angle (θ / 2) of the head unit 3. As a result, the reflected lights RL1 and RL2 do not rotate but are directly guided to the imaging unit 6 via the optical path length difference correction unit 5, and the orientation of the image captured by the imaging unit 6 is maintained constant. Since the configuration and operation of the image rotation correction unit 4 are described in detail in Patent Document 1, description of the configuration and operation of the image rotation correction unit 4 in this specification is omitted.

Here, when the optical path lengths of the reflected lights RL1 and RL2 emitted from the image rotation correction unit 4 are compared, the folding mirror 32 is further away from the image rotation correction unit 4 than the folding mirror 31 in the head unit 3, that is, on the tip side. Therefore, the optical path length of the reflected light RL2 is longer than the optical path length of the reflected light RL1. For this reason, if the reflected lights RL1 and RL2 emitted from the image rotation correction unit 4 enter the imaging unit 6 as they are, a focus shift occurs between the regions R1 and R2, and the images are captured well together. Difficult to do. Therefore, in this embodiment, the optical path length difference correction unit 5 in which two optical

path changing mirrors

51 and 52 are combined is interposed between the image rotation correction unit 4 and the imaging unit 6.

2 and 3, the optical path length difference correction unit 5 includes an optical path changing mirror 51 that is disposed in the Y direction away from the optical path of the reflected light RL2 and reflects only the reflected light RL1, and an optical path changing mirror 51. An optical path changing mirror 52 that turns the reflected light RL1 that is turned back toward the imaging unit 6 is provided. Therefore, in the optical path length difference correction unit 5, as shown in FIG. 3, the reflected light RL1 is reflected by the amount of the reflected light RL1 that is reflected at the reflection position C1 of the optical path change mirror 51 and the reflection position D1 of the optical path change mirror 52. The optical path length becomes longer than the optical path length of the reflected light RL2. That is, in the present embodiment, for each of the reflected lights RL1 and RL2 emitted from the image rotation correction unit 4, the optical path length of the reflected light from the image rotation correction unit 4 to the imaging unit 6 is reflected by the reflected light RL1 and RL2 in the head unit 3. It is adjusted according to the optical path length difference. Thereby, the optical path length of the reflected light RL1 from the reflection position A1 to the incident position E1 (FIG. 3) to the imaging unit 6, and the reflected light RL2 from the reflection position A2 to the incident position E2 (FIG. 3) to the imaging unit 6. It is possible to make the optical path lengths substantially coincide with each other. The analysis will be described later with reference to FIGS.

FIG. 4 is a diagram showing a main configuration of the imaging unit. The imaging unit 6 includes an optical system 63 including two

lenses

631 and 632 and a diaphragm 633 in addition to the half mirror 61 and the imaging element 62 described above, and constitutes so-called object-side telecentric and reflection. Lights RL 1 and RL 2 are condensed on the imaging surface 621 of the imaging device 62, respectively, and images of the regions R 1 and R 2 are formed on the imaging surface 621. Although not shown in FIG. 4, in the imaging apparatus 100, the illumination light IL from the light source 7 is emitted from the imaging unit 6, the optical path length correction unit 5, the image rotation correction unit 4, and the head unit 3 as described above. This is a so-called coaxial epi-illumination system that irradiates the inner peripheral surface 14 of the through-hole 13 via the. For this reason, the following effects are obtained.

As described above, the workpiece 1 is made of metal, the through-hole 13 is formed by cutting or the like, and the inner peripheral surface 14 often requires relatively high accuracy. For this reason, the inner peripheral surface 14 is in a state close to a mirror surface. When a defect portion such as a scratch or chip exists on the inner peripheral surface 14, scattered light is generated in the defect portion. On the other hand, the mirror surface state is maintained at the part other than the defect part, and the scattered light component from the mirror surface part is small. Therefore, by combining the feature of object-side telecentricity and the feature of adopting coaxial epi-illumination as in the present embodiment, the reflected light RL1 and RL2 become specularly reflected light, and there is a defect part. Includes a defective part clearly in the image picked up by the image pickup unit 6. As a result, it is possible to easily inspect whether or not a defect exists.

As described above, according to the present embodiment, the head portion 3 in which the folding mirrors 31 and 32 are arranged at different positions in the Z direction is inserted into the through hole 13 of the workpiece 1. The illumination light IL is guided to the regions R1 and R2 that are different from each other in the Z direction in the inner peripheral surface 14 in the inserted state, and the reflected lights RL1 and RL2 reflected by the regions R1 and R2 are taken out from the through hole 13. The image sensor 62 of the imaging unit 6 receives light. For this reason, it is possible to simultaneously image the two regions R1 and R2 included in the inner peripheral surface 14 of the through hole 13, and the inner peripheral surface 14 of the through hole 13 can be imaged in a short time.

In addition, by providing the two folding mirrors 31 and 32 in the head unit 3, an optical path length difference occurs between the reflected lights RL 1 and RL 2 in the head unit 3, but by providing the optical path length difference correction unit 5, as shown in FIG. As described above, the optical path length from the inner peripheral surface 14 to the incident side lens 631 of the reflected light RL1 and RL2 is several dimensions and values based on the apparatus specifications as described in detail below. Can be set equal to each other, and the focus can be made to coincide for each of the regions R1 and R2, and the inner peripheral surface 14 of the through hole 13 can be imaged satisfactorily.

Next, the optical path length from the inner peripheral surface 14 to the incident side lens 631 in the imaging unit 6 will be described in detail with reference to FIGS. FIG. 5 is a plan view of the optical path length difference correction unit 5, the image rotation correction unit 4 and the head unit 3 shown in FIG. 3 viewed from the Z direction, that is, an XY plan view. FIG. 6 is a side view of the optical path length difference correcting unit 5, the image rotation correcting unit 4 and the head unit 3 shown in FIG. 3 as viewed from the Y direction, that is, an XZ plan view. 7 is a side view of the optical path length difference correction unit 5, the image rotation correction unit 4 and the head unit 3 shown in FIG. 3 as viewed from the X direction, that is, a YZ plan view. 5 and 7, the illustration of the image rotation correction unit 4 is omitted. Also, the symbols dx, dy1, dy2, dz, L1, L2, L3, and rw in FIGS. 5 to 7 are as follows.

dx: distance between mirrors of the optical

path changing mirrors

51 and 52 in the X direction,
dy1: the distance between the

mirrors

31 and 32 in the Y direction,
dy2: distance between mirrors of the folding mirror 31 and the optical path changing mirror 51 in the Y direction,
dz: the distance between the

mirrors

31 and 32 in the Z direction,
L1: Distance between mirrors of folding mirror 31 and optical path changing mirror 51 in the Z direction (however, including reflection of reflected light by correction mirrors 41 to 43),
L2: Distance between mirrors of the optical

path changing mirrors

51 and 52 in the Z direction,
L3: distance between the optical path changing mirror 52 and the entrance surface of the lens 631 in the Z direction,
rw: radius of the inner peripheral surface 14,
α1: Reflection angle of the folding mirror 31 in the YZ plane,
α2x: reflection angle of the optical path changing mirror 51 in the XZ plane,
α2y: Reflection angle of the optical path changing mirror 51 in the YZ plane.

Here, first, the optical path length of the reflected light RL1 will be examined. As shown in FIG. 6, the reflected light RL1 is incident on the imaging unit 6 through an optical path of position A1-position B1- (image rotation correction unit 4) -position C1-position D1-position E1. For this reason, the distance between adjacent positions is as shown in the following equation.

On the other hand, as shown in FIG. 6, the reflected light RL2 is incident on the imaging unit 6 through an optical path of position A2-position B2- (image rotation correction unit 4) -position C2-position D2-position E2. For this reason, the distance between adjacent positions is as shown in the following equation.

And in order to make the optical path length of reflected light RL1 and RL2 equal, it is necessary to satisfy the following formula.

Substituting the

above formulas

1 and 2 into this and rearranging the inter-mirror distance L2 of the optical

path changing mirrors

51 and 52 in the Z direction, the following formula is obtained.

On the other hand, the reflection angle α1 of the folding mirror 31 in the YZ plane, the reflection angle α2x of the optical path changing mirror 51 in the XZ plane, and the reflection angle α2y of the optical path changing mirror 51 in the YZ plane are shown in FIGS. As is clear, it is expressed by the following equation.

Therefore, when the distances dx, dy1, dy2, dz, L1, and L3 are determined from the specifications of each part of the imaging apparatus 100, the optical

path changing mirrors

51 and 52 in the Z direction are determined based on the condition that the optical path lengths of the reflected lights RL1 and RL2 are equal. A mirror distance L2 is obtained. In addition, the reflection angles α1, α2x, and α2y are uniquely determined from the above equation of the reflection angle. In this way, the specific configuration of each part of the optical path length difference correction unit 5, the image rotation correction unit 4, and the head unit 3 can be determined. In the imaging device 100 assembled in accordance with this, the two reflected lights RL1, Not only can the inner peripheral surface 14 be imaged in a short time by receiving light of the RL 2 by the imaging unit 6, but also the inner peripheral surface 14 of the through hole 13 can be favorably imaged.

Further, as described above, the reflection mirrors 31 and 32 are arranged so that the surface normal of the mirror surface 311 is slightly inclined with respect to the surface normal of the mirror surface 312, and the reflection angle α1 is provided. As a result, the reflected light RL1 and RL2 incident on the optical path length difference correction unit 5 are separated in the Y direction, and the reflected light RL2 passes through the side of the optical path changing mirror 51 and is guided to the imaging unit 6. The reflected light RL1 is guided to the imaging unit 6 after being reflected by the optical

path changing mirrors

51 and 52. As a result, although the reflected lights RL1 and RL2 have a spread corresponding to the object-side numerical aperture, the reflected lights RL1 and RL2 can be separated and guided along a desired optical path as described above.

Note that the present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, two folding mirrors 31 and 32 are provided in the head unit 3 and two regions R1 and R2 that are different from each other in the Z direction are simultaneously imaged. However, the number of folding mirrors is three or more. Also good. In short, the plurality of folding mirrors may be configured to guide the illumination light IL to different regions in the Z direction on the inner peripheral surface 14 and to extract the reflected light reflected by the region from the through hole 13. . In this case, the number of optical path changing mirrors provided in the optical path length difference correction unit 5 may be increased as the number of folding mirrors increases.

Moreover, in the said embodiment, although the workpiece | work 1 in which the through-hole 13 was formed is used as the "imaging target object" of this invention, it can also image the workpiece | work in which the recessed part shallower than the thickness of the metal plate was formed from the surface 11. Is possible. That is, the “hole” of the present invention includes both a through hole and a recess. The material of the workpiece is not limited to a metal material, and may be a ceramic material, a resin material, or a rubber material, and various workpieces can be imaged as an imaging object.
While the invention has been described with reference to specific embodiments, this description is not intended to be construed in a limiting sense. Reference to the description of the invention, as well as other embodiments of the present invention, various modifications of the disclosed embodiments will become apparent to those skilled in the art. Accordingly, the appended claims are intended to include such modifications or embodiments without departing from the true scope of the invention.

The present invention can be applied to all imaging devices that image the inner peripheral surface of a hole formed in the hole forming direction from the surface of the imaging object.

1 ... Work (object to be imaged)
DESCRIPTION OF SYMBOLS 3 ... Head part 4 ... Image rotation correction | amendment part 5 ... Optical path length difference correction part 6 ... Imaging part 7 ... Light source 11 ... Surface of (work) 13 ... Through-hole 14 ... Inner peripheral surface (of through-hole) 31 ... Folding mirror 32 ... (tip) folding

mirror

51, 52 ... optical path changing mirror 63 ... optical system 100 ... imaging device IL ... illumination light R1, R2 ... area RL1 ... reflected light RL2 ... (tip) reflected light Z ... hole forming direction θ ... rotation angle

Claims

An imaging device that images an inner peripheral surface of a hole formed in a hole forming direction from the surface of an imaging object by an imaging unit,
A light source that emits illumination light for illuminating the inner peripheral surface;
A plurality of folding mirrors, and each of the plurality of folding mirrors guides the illumination light to different areas of the inner circumferential surface in the hole forming direction and reflects reflected light reflected by the areas from the holes. A head portion that rotates around a rotation axis parallel to the hole forming direction while being inserted into the hole so as to be removed;
The plurality of reflected lights extracted from the head unit are guided toward the imaging unit while rotating around the rotation axis so that a rotation angle per unit time is a half rotation angle of the head unit. An image rotation correction unit that maintains a constant orientation of an image captured by the imaging unit;
For each reflected light emitted from the image rotation correction unit, an optical path length of the reflected light from the image rotation correction unit to the imaging unit is adjusted according to an optical path length difference of the plurality of reflected lights in the head unit. An imaging apparatus comprising: an optical path length difference correction unit configured to guide light to the imaging unit.
The imaging apparatus according to claim 1,
The image pickup unit includes an image pickup device and an optical system that causes the plurality of reflected lights emitted from the optical path length difference correction unit to enter the image pickup device and forms an image of the inner peripheral surface on the image pickup device. And
The imaging apparatus in which the illumination light emitted from the light source is applied to the inner peripheral surface via the optical system, the optical path length difference correction unit, the image rotation correction unit, and the head unit.
The imaging apparatus according to claim 1, wherein:
The imaging apparatus in which the plurality of folding mirrors are arranged at different positions in a plane orthogonal to the hole forming direction.
The imaging apparatus according to claim 3,
When the folding mirror that is farthest from the image rotation correction unit among the plurality of folding mirrors is used as a tip folding mirror, and the reflected light extracted by the tip folding mirror is used as a tip reflected light,
The optical path length difference correction unit includes an optical path changing mirror arranged out of the optical path of the tip reflection light, and the optical path length difference correction unit other than the tip reflection light among the plurality of reflection lights emitted from the image rotation correction unit. An imaging apparatus that reflects the reflected light by the optical path changing mirror to change an optical path and guides the reflected light to the imaging unit, and guides the reflected light at the tip as it is to the imaging unit to adjust an optical path length.
The imaging apparatus according to claim 4,
An imaging device for guiding the reflected light to the optical path changing mirror, wherein a folding mirror other than the tip folding mirror among the plurality of folding mirrors has a surface normal inclined with respect to a surface normal of the tip folding mirror .