JP2013252256A - Image guide and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image guide capable of suppressing both of an occurrence of moire phenomenon and deterioration in image quality, and to provide an imaging apparatus.SOLUTION: An imaging apparatus 1 includes an image guide 10, an imaging unit 20, and a lens 21, and observes an object 9. The image guide 10 is formed by binding and integrating a plurality of optical fibers 11, and outputs an optical image generated from the object 9 and input in a first end (in the side of the object 9), from a second end (in the side of the imaging unit 20). In the image guide 10, respective outside diameters of the plurality of optical fibers 11 are mutually equal. At least one optical fiber of the plurality of optical fibers 11 has a core at a position deflected from the center.

Description

  The present invention relates to an image guide and an imaging apparatus.

  An image guide in which a plurality of single core optical fibers are bundled and integrated to output an image of light input to the first end from the second end, and a second input to the first end of the image guide. An imaging device including an imaging unit that acquires an image of light output from an end is known. In such an imaging apparatus, if a plurality of optical fibers included in the image guide have a common configuration and are arranged in an orderly manner, a moire phenomenon may occur in an image acquired by the imaging unit. Therefore, in order to suppress the occurrence of the moire phenomenon, it is known that the core diameter or the fiber diameter of the plurality of optical fibers included in the image guide is made non-uniform or the arrangement of the plurality of optical fibers is randomized. .

Japanese Utility Model Publication No. 61-36803

  However, the above technique for suppressing the occurrence of the moire phenomenon has the following problems. If the core diameters of a plurality of optical fibers are made non-uniform, the pixel size becomes non-uniform and uneven brightness occurs. Further, since it is necessary to prepare optical fibers having various core diameters, the number of parts is large. If the fiber diameters of the plurality of optical fibers are made non-uniform, the filling rate of the optical fibers is lowered, so that the pixel density is lowered and the image quality is lowered.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an image guide and an imaging apparatus capable of suppressing both the occurrence of a moire phenomenon and a decrease in image quality.

  The image guide of the present invention is an image guide for outputting an image of light input to the first end from the second end, and a plurality of optical fibers having the same outer diameter are bundled and integrated. Thus, at least one of the plurality of optical fibers has a core at a position off the center. In each of the plurality of optical fibers, the relative refractive index difference of the core with respect to the cladding is preferably 3.0% to 3.5%. Moreover, it is preferable that the cross-sectional shape of each of the plurality of optical fibers is a polygon. Each of the plurality of optical fibers is preferably a multi-core optical fiber having a plurality of cores having the same outer diameter.

  An imaging apparatus of the present invention includes (1) the image guide of the present invention described above, and (2) an imaging unit that acquires an image of light that is input to the first end of the image guide and output from the second end, It is characterized by providing. The imaging unit may include processing means for imaging light of a predetermined wavelength among light output from the second end of the image guide.

When the optical fiber included in the image guide of the present invention is a multi-core optical fiber, the imaging apparatus of the present invention includes (1) the image guide of the present invention, and (2) M multi-core light included in the image guide. at the second end with respect to the fiber _F 1 to F _M each of the n cores _C 1 -C _n are optically connected, optically connected to the cores _{C n} of the n of the multi-core optical fiber _{F m} A plurality of branching single-core optical fibers in which the n-th group is bundled in the same arrangement at the entrance end and the exit end; and (3) the first group to the N-th of the plurality of branching single-core optical fibers. An optical filter that selectively outputs light having different wavelengths between the groups from the emission end, and (4) a first group to a first group of single-core optical fibers for branching that are input to the first end of the image guide. Output from the output end of each N group Provided that an imaging unit for acquiring an image of light. However, M and N are integers of 2 or more, m is an integer of 1 to M, and n is an integer of 1 to N.

In the image guide of the present invention, it is preferable that each of the plurality of optical fibers has an optical filter that selectively outputs light having different wavelengths between the plurality of cores from the second end. At this time, the imaging apparatus of the present invention includes (1) the image guide of the present invention, and (2) N cores C ₁ to C of each of the _M multi-core optical fibers F _{1 to} F _M included in the image guide. at the second end to C _n are optically connected, the arrangement between the exit end and the incident end ones of the n groups which are optically connected to the cores C _n of the n of the multi-core optical fiber F _m A plurality of branching single-core optical fibers bundled together at (3), and output ends of the first group to the Nth group of the plurality of branching single-core optical fibers input to the first end of the image guide. And (4) an optical filter that emits light having different wavelengths between the first group to the Nth group of the plurality of branching single-core optical fibers. Selectively output from the output end.

  In the image guide of the present invention, in each of the plurality of optical fibers, it is preferable that any one of the plurality of cores outputs illumination light input to the second end from the first end. At this time, the imaging apparatus of the present invention outputs (1) the image guide of the present invention and (2) the illumination light, and outputs the second end of the specific core of each of the multiple multi-core optical fibers included in the image guide. A light source unit that causes the illumination light to enter, and (3) an imaging unit that acquires an image of light that is input to the first end of a core other than the specific core of each of the multi-core optical fibers and output from the second end And comprising.

  In the imaging apparatus of the present invention, the imaging unit acquires the intensity of the three-dimensional infrared reflection spectrum composed of the surface position and the wavelength direction from the biological tissue based on the light image output from the second end of the image guide. An infrared reflection spectrum acquisition means and a calculation means for identifying normality / abnormality of the biological tissue based on the infrared reflection intensity obtained by the infrared reflection spectrum acquisition means may be included. The imaging apparatus according to the present invention includes (1) an image guide according to the present invention, and (2) illuminating an object with illumination light at a first end of a specific core of each of a plurality of multi-core optical fibers included in the image guide. A light source unit that makes the reflected light from the object incident; and (3) an imaging unit that receives the reflected light emitted from the second end of the image guide and analyzes the spectral data of the object. .

  According to the present invention, it is possible to suppress both the occurrence of a moire phenomenon and a reduction in image quality.

It is a figure which shows the structure of the imaging device 1 of 1st Embodiment. It is a figure which shows the structure of the imaging device 2 of 2nd Embodiment. It is a figure which shows the structure of the imaging device 3 of 3rd Embodiment. It is a figure which shows the structure of the imaging device 4 of 4th Embodiment. It is a figure which shows the structure of the imaging device 5 of 5th Embodiment. It is a figure which shows the structure of the imaging device 6 of 6th Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  (First embodiment)

  FIG. 1 is a diagram illustrating a configuration of an imaging apparatus 1 according to the first embodiment. FIG. 1A shows the overall configuration of the imaging apparatus 1. The imaging device 1 includes an image guide 10, an imaging unit 20, and a lens 21, and can observe the object 9. The image guide 10 is formed by bundling and integrating a plurality of optical fibers 11, and an image of light emitted from the object 9 and input to the first end (object 9 side) is captured at the second end (imaging). From the unit 20 side).

  In the image guide 10, the outer diameters of the plurality of optical fibers 11 are equal to each other. At least one of the plurality of optical fibers 11 has a core at a position off the center. The imaging unit 20 includes a CCD camera, for example, and can acquire an image of light that is input to the first end of the image guide 10 and output from the second end through the lens 21. The imaging apparatus 1 and the image guide 10 configured as described above can suppress both the occurrence of the moire phenomenon and the deterioration of the image quality.

  In the conventional image guide, when the optical fiber is packed most closely, the spatial frequency of each pixel and the spatial frequency of the camera are close to each other, and there is a problem that moire fringes are generated in the image. On the other hand, in the image guide 10 of this embodiment, the spatial frequency of each pixel is randomized by using the optical fiber 11 having the core at a position off the center, and moire is less likely to occur. Further, since the outer diameters of the plurality of optical fibers 11 are equal to each other, when the plurality of optical fibers 11 are bundled, each of them can be packed most closely, so that the packing density of the plurality of optical fibers 11 is high. Get higher. As a result, the pixel density of the image acquired in the imaging unit 20 through the image guide 10 can be increased, and the image quality can be improved. That is, the imaging device 1 and the image guide 10 of the present embodiment can suppress both the occurrence of moire phenomenon and the deterioration of image quality.

  The plurality of optical fibers 11 are filled in a pipe-shaped support 14. The support 14 is made of, for example, quartz glass. A plurality of optical fibers 11 may be heated and stretched while being inserted into the support 14. The cross-sectional shape of each of the plurality of optical fibers 11 is preferably a polygon such as a regular triangle, a square, and a regular hexagon. In this way, it is possible to perform the closest packing so that no gap is generated between the plurality of optical fibers 11. The cross-sectional shape of the internal space of the support 14 is also preferably a polygonal shape so that the plurality of optical fibers 11 can be accommodated without gaps in a state of being closely packed. For example, when the outer shape of the optical fiber 11 is a quadrangle, the plurality of optical fibers 11 are packed most closely in a four-sided arrangement, so that the internal space is also preferably a quadrangle. Further, when the outer shape of the optical fiber 11 is a regular triangle or a regular hexagon, the plurality of optical fibers 11 are closely packed in a hexagonal array (triangular lattice array), and therefore the internal space is preferably a regular hexagon. . In this case, the packing density of the plurality of optical fibers 11 in the support 14 is increased. As a result, the pixel density of the image acquired in the imaging unit 20 through the image guide 10 can be increased, and the image quality can be improved.

  Moreover, it is preferable that the plurality of optical fibers 11 applied to the image guide 10 of the present embodiment is a multi-core optical fiber (FIG. 5B). The multi-core optical fiber 11 has a plurality of cores 12 having the same outer diameter in a common clad 13. In each multi-core optical fiber 11, at least one of the plurality of cores 12 is at a position off the fiber center. In this case, since the number of pixels included in each optical fiber 11 can be increased, the pixel density of the image acquired in the imaging unit 20 can be further increased, and the image quality can be improved. Furthermore, since the position of the core 12 at a position off the center can be changed by rotating the multi-core optical fiber, a multi-core optical fiber having the same core arrangement and outer diameter is applied to the plurality of optical fibers 11. In addition, it is easy to make the positions of the cores 12 at positions off the center different from each other while making the closest packing, so it is easy to randomize the spatial frequency of each pixel. That is, the occurrence of the moire phenomenon can be suitably suppressed.

  In each of the plurality of optical fibers 11, it is preferable that the relative refractive index difference of the core with respect to the cladding is 3.0% to 3.5%. Thus, when the relative refractive index difference of the core is large, crosstalk between the cores is suppressed, and deterioration in image quality due to crosstalk can be suppressed. This effect is significant when the optical fiber 11 is a multi-core optical fiber (FIG. 5B).

  (Second Embodiment)

  FIG. 2 is a diagram illustrating a configuration of the imaging apparatus 2 according to the second embodiment. FIG. 1A shows the overall configuration of the imaging apparatus 2. FIG. 2B shows the end face of the multi-core optical fiber 11. Compared to the case of the first embodiment, the imaging device 2 of the second embodiment is configured such that, in an image guide 10 </ b> A that replaces the image guide 10, any one of the plurality of cores 12 of each multi-core optical fiber 11 ( The difference is that the illumination light input to the second end is output from the first end to irradiate the object 9 with a plurality of cores of each multi-core optical fiber 11. It differs in the point by which the optical filters 31-34 are provided in the end surface of other cores except the specific core among the cores 12.

  By irradiating the object 9 with illumination light (for example, broadband light or near infrared light) using a specific core of each multi-core optical fiber 11, the object 9 can be efficiently irradiated with illumination light, The object 9 can be observed efficiently.

  The optical filters 31 to 34 can selectively transmit light having different wavelengths. The optical filters 31 to 34 are, for example, dielectric multilayer films. By using the image guide 10A in which the multi-core optical fiber 11 having such an optical filter is bundled, both the occurrence of the moire phenomenon and the deterioration of the image quality are suppressed, and the object 9 is observed at high speed with multi-wavelength light. Can do.

  For example, when observing an object with four wavelengths of light, the conventional method requires 80 msec to switch the four wavelengths of light, but in this embodiment, the measurement time can be shortened to 1/8 of 10 msec. It is. In the conventional method, since it takes 80 msec to switch the four wavelengths, if the object moves during that time, the observation result is affected, but in this embodiment, the influence due to the movement can be eliminated. The switching time of the optical switch is a maximum of 10 msec, and it is necessary to synchronize with the image acquisition time of 10 msec at a frame rate of 100 Hz of the image pickup unit. It takes a measurement time of 20 msec per wavelength, but theoretically, the camera frame rate time is up to 10 msec. Can be shortened.

  (Third embodiment)

FIG. 3 is a diagram illustrating a configuration of the imaging device 3 according to the third embodiment. The imaging device 3 includes an image guide 10, an imaging unit 20, a lens 21, and a light source unit 40. The configuration of the image guide 10 is the same as that in the first embodiment. The light source unit 40 outputs illumination light and irradiates the object 9 with the illumination light. As the light source unit 40, for example, an SC light source, an ASE light source, an SLD, a halogen lamp, or the like can be used. The imaging device 3 having such a configuration can also suppress both the occurrence of moiré phenomenon and a reduction in image quality. Light source unit 40, the illumination light obliquely incident on the object 9 as shown, the diffused reflected light L ₁ to take the form to be incident on the image guide 10, one of the light constituting the image guide 10 to be incident on the object 9 with illumination light through the fiber may take the form for entering the specularly reflected light L ₂ to the image guide 10.

  The imaging unit 20 may be configured to calculate the intensity of light for each light corresponding to a predetermined wavelength region and acquire a two-dimensional image of each wavelength region. For example, as shown in a later embodiment, an optical system that splits light incident on the image fiber 10 into a plurality of wavelength regions is provided, and a two-dimensional image of each wavelength region after the spectrum is acquired by an imaging unit You may do it. Alternatively, the light incident on the image fiber 10 can be collectively received by the imaging unit, photoelectrically converted and acquired as an electrical signal, and then the intensity of light corresponding to each wavelength region can be calculated and output separately. A configuration may be adopted.

  Such an imaging device 3 can be suitably applied to a biological tissue identification device that identifies normality / abnormality of biological tissue from infrared spectrum information. For example, in Japanese Patent Application Laid-Open No. 2009-39280, an optical system that splits radiated light or reflected light from a subject into a plurality of wavelength regions defined by a hyperspectrum, and light that is split by the optical system is received for each wavelength region. And calculating the intensity of light in each wavelength region based on the electrical signal and an imaging element having a plurality of pixels that photoelectrically convert to generate an electrical signal, and the relationship between the plurality of wavelength regions and the light intensity in the pixel. And an analysis unit for analyzing the component of the emitted light or reflected light from the subject in order to identify the affected part of the subject by hyperspectral analysis. In Japanese Patent Application Laid-Open No. 2011-83486, hyperspectral data H (x0, y0, λ0) is a two-dimensional image plane cut at a wavelength λ0, and the data in the wavelength direction is integrated by changing the wavelength. It is shown that data in the wavelength direction is acquired for each wavelength using a combination of a spectroscope, a movable slit and an electrostatic actuator, LVF, grism, etc. Yes. That is, in order to acquire data for each wavelength, it is necessary to switch to make light of a desired wavelength incident on the measurement object, and in order to capture a plurality of wavelength data, the measurement time becomes long.

  On the other hand, the imaging device 3 of the present embodiment can acquire the data of the two-dimensional image plane of each wavelength, that is, the hyperspectral data without switching the incident light for each wavelength, thereby reducing the measurement time. be able to. Such a biological tissue identification device includes an infrared reflection spectrum acquisition unit that acquires the intensity of a three-dimensional infrared reflection spectrum consisting of a surface position and a wavelength direction from a biological tissue using the imaging device of the present embodiment, and an infrared And a calculation means for identifying normality / abnormality of a biological tissue based on the infrared reflection intensity obtained by the reflection spectrum acquisition means. The imaging apparatus can be applied as appropriate.

  (Fourth embodiment)

  FIG. 4 is a diagram illustrating a configuration of the imaging device 4 according to the fourth embodiment. The imaging device 4 includes an image guide 10, an imaging unit 20, optical filters 31 to 34, a light source unit 40, a tap 41, a monitor unit 42, branching single core optical fibers 51 to 54, and an illumination optical fiber 60.

  The illumination light output from the light source unit 40 is guided by the illumination optical fiber 60 through the tap 41 and is obliquely irradiated to the object 9. A part of the illumination light is branched by the tap 41 and the power is monitored by the monitor unit 42. For example, a photodiode may be used as the monitor unit 42.

Optical filters 31 to 34 are provided on the core end surfaces of the multi-core optical fibers 11 at the first end (the object 9 side) of the image guide 10. The optical filter 31 is capable of selectively transmitting light of wavelength lambda _1. The optical filter 32 is capable of selectively transmitting light of wavelength lambda _2. The optical filter 33 is capable of selectively transmitting light of wavelength lambda _3. The optical filter 34 is capable of selectively transmitting light of wavelength lambda _4.

  At the second end (on the imaging unit 20 side) of the image guide 10, branching single core optical fibers 51 to 54 are optically connected to the cores of the multicore optical fibers 11. In order to optically connect each core of a multicore optical fiber and a single core optical fiber, for example, an arrangement of a plurality of cores of a multicore optical fiber and a core arrangement of a plurality of single core optical fibers correspond to each other. Each may be fixed to a ferrule and connected by a sleeve.

A group (first group) of branching single-core optical fibers 51 connected to a core that outputs light having a wavelength λ ₁ among a plurality of cores of each multi-core optical fiber 11 has the same arrangement at an incident end and an output end. It is bundled. Group of a plurality of branching single-core optical fiber 52 connected to a core that outputs light of wavelength lambda ₂ of the core of the multi-core optical fiber 11 (second group), in the same sequence at the exit end and the incident end It is bundled. A group (third group) of branching single-core optical fibers 53 connected to a core that outputs light of wavelength λ ₃ among a plurality of cores of each multi-core optical fiber 11 has the same arrangement at the incident end and the outgoing end. It is bundled. Group of a plurality of cores of the wavelength lambda ₄ of branching single-core optical fiber 54 connected to the core for outputting light of each multi-core optical fiber 11 (fourth group), in the same sequence at the exit end and the incident end It is bundled.

The imaging unit 20 acquires an image of light having the wavelength λ ₁ output from the emission end of the first group branching single-core optical fiber 51 among the light input to the first end of the image guide 10, and An image of light having a wavelength λ ₂ output from the exit end of the second group of branching single-core optical fibers 52 is acquired, and the wavelength λ ₃ output from the exit end of the third group of branching single-core optical fibers 53 is acquired. An image of light can be acquired, and an image of light having a wavelength λ ₄ output from the output end of the fourth group of single-core optical fibers for branching 54 can be acquired. The imaging apparatus 4 can simultaneously acquire images of light having _four wavelengths λ _{1 to} λ 4 while suppressing both the occurrence of a moire phenomenon and a decrease in image quality.

  (Fifth embodiment)

  FIG. 5 is a diagram illustrating a configuration of the imaging device 5 according to the fifth embodiment. Compared to the case of the fourth embodiment, the imaging device 5 of the fifth embodiment is different in that the optical filters 31 to 34 are provided at the emission ends of the branching single core optical fibers 51 to 54.

  Also in the present embodiment, branching single-core optical fibers 51 to 54 are optically connected to the respective cores of the multi-core optical fibers 11 at the second end (on the imaging unit 20 side) of the image guide 10. An optical filter 31 is provided at the exit end of the group (first group) of branching single core optical fibers 51. The optical filter 32 is provided at the exit end of the group (second group) of the branching single core optical fibers 52. An optical filter 33 is provided at the exit end of the group (third group) of the branching single core optical fibers 53. An optical filter 34 is provided at the exit end of the group (fourth group) of the branching single core optical fibers 54.

The imaging unit 20 acquires an image of light having the wavelength λ ₁ output from the emission end of the first group branching single-core optical fiber 51 among the light input to the first end of the image guide 10, and An image of light having a wavelength λ ₂ output from the exit end of the second group of branching single-core optical fibers 52 is acquired, and the wavelength λ ₃ output from the exit end of the third group of branching single-core optical fibers 53 is acquired. An image of light can be acquired, and an image of light having a wavelength λ ₄ output from the output end of the fourth group of single-core optical fibers for branching 54 can be acquired. The imaging apparatus 5 can also acquire images of light having _four wavelengths λ _{1 to} λ ₄ at the same time while suppressing both occurrence of moire phenomenon and image quality degradation.

  (Sixth embodiment)

FIG. 6 is a diagram illustrating a configuration of the imaging device 6 according to the sixth embodiment. Compared to the case of the fifth embodiment, the imaging device 6 of the sixth embodiment is different in that it includes an image guide 10A instead of the image guide 10A, and the illumination light output from the light source unit 40 is used as the image guide 10A. Are different in that they are guided by a specific core of each of the multi-core optical fibers 11A and irradiated onto the object 9. The imaging device 6 can also acquire images of light of four wavelengths λ _{1 to} λ ₄ at the same time while suppressing both the occurrence of moire phenomenon and image quality degradation.

  (Seventh embodiment)

  The imaging device 3 shown in FIG. 3 can also be used as an apparatus for inspecting foreign matters contained in food as the object 9, for example, as described below. When the imaging device 3 is used as a foreign matter inspection device, for example, the food as the object 9 is irradiated with visible light or near infrared light from the light source unit 40, and reflected light from the food is image guide 10 and the lens 21. The spectral data of the reflected light is obtained by receiving the light through the imaging unit 20, and the state of the object is evaluated using the spectral data. The configuration of the image guide 10 is the same as in the first embodiment, but the plurality of optical fibers 11 applied to the image guide 10 are multi-core optical fibers. The light source unit 40 outputs illumination light and irradiates the object 9 with the illumination light. Reflected light from the object 9 is guided to the imaging unit 20 through the image guide 10 and the lens 21, and spectrum data is acquired by the imaging unit 20. Then, the state of the object 9 is evaluated by analyzing the spectrum data. As the light source unit 40, for example, an SC light source, an ASE light source, an SLD, a halogen lamp, or the like can be used.

  When the imaging device 3 is used as a foreign substance inspection device, the image guide 10 does not have a function of acquiring image data, but the core is located at a position where a plurality of optical fibers 11 applied to the image guide 10 are off the center. By using the multi-core optical fiber 12, the reflected light can be sufficiently collected by many cores and guided to the imaging unit 20. Also, randomizing the spatial frequency of each core prevents unnecessary interference from occurring in the emitted light. As a result, inspection accuracy can be improved.

  At this time, the illumination light is preferably incident on the object 9 at an angle. Specifically, the illumination path (preferably near-infrared light, that is, light having a wavelength range of 800 nm to 2500 nm) output from the light source unit 40 is regularly reflected on the surface of the object 9, and the illumination light. It is preferable that an angle a <b> 1 formed by a straight line connecting the surface of the inspection object 9 to be irradiated with the imaging unit 20 is 45 ° or more. When the object 9 is irradiated with illumination light in this way, specular reflection light and diffuse reflection light are generated, but diffuse reflection light is measured as in the present embodiment, and based on the result of the object 9 In the case of a foreign substance inspection apparatus that evaluates quality, it is an important factor to improve evaluation accuracy to appropriately detect diffuse reflected light. Therefore, in order to increase the evaluation accuracy, it is necessary to prevent regular reflection light from entering the imaging unit 20.

  As in the present embodiment, when the angle a1 is 45 ° or more, even if the shape of the object 9 at the irradiation light irradiation position P1 is uneven, the regular reflection light is incident on the imaging unit 20. Therefore, quality evaluation by the imaging device 3 can be performed with high accuracy. Further, since the plurality of optical fibers 11 applied to the image guide 10 is a multi-core fiber having a core 12 at a position deviated from the center, the object 9 and the image guide 10 are prevented from entering the regular reflected light. Even if an appropriate interval is provided between them, sufficient diffuse reflection light can be collected, so that diffuse reflection light can be appropriately acquired with respect to regular reflection light, and the evaluation system can be enhanced.

  DESCRIPTION OF SYMBOLS 1-6 ... Imaging device, 9 ... Object, 10 ... Image guide, 11 ... Optical fiber, 12 ... Core, 13 ... Cladding, 14 ... Support, 20 ... Imaging part, 21 ... Lens, 31-34 ... Optical filter, DESCRIPTION OF SYMBOLS 40 ... Light source part, 41 ... Tap, 42 ... Monitor part, 51-54 ... Single core optical fiber for branch, 60 ... Optical fiber for illumination

Claims (13)

  An image guide for outputting an image of light input to the first end from the second end, wherein a plurality of optical fibers having the same outer diameter are bundled together and integrated. An image guide, characterized in that at least one optical fiber of the fibers has a core at a position off the center.   2. The image guide according to claim 1, wherein the relative refractive index difference of the core with respect to the cladding in each of the plurality of optical fibers is 3.0% to 3.5%.   The image guide according to claim 1, wherein each of the plurality of optical fibers has a polygonal cross-sectional shape.   The image guide according to claim 1, wherein each of the plurality of optical fibers is a multi-core optical fiber having a plurality of cores having the same outer diameter.   5. The image guide according to claim 4, wherein each of the plurality of optical fibers includes an optical filter that selectively outputs light having wavelengths different from each other between the plurality of cores from the second end. .   5. In each of the plurality of optical fibers, any one of the plurality of cores outputs illumination light input to the second end from the first end. The image guide described. The image guide according to any one of claims 1 to 4,
An imaging unit that acquires an image of light that is input to the first end of the image guide and output from the second end;
An imaging apparatus comprising:   The imaging apparatus according to claim 7, wherein the imaging unit includes processing means for imaging light having a predetermined wavelength among light output from the second end of the image guide. An image guide according to claim 4;
The N cores C _{1 to} C _N of the _M multi-core optical fibers F _{1 to} F _M included in this image guide are optically connected at the second end, and the n-th of each multi-core optical fiber F _m is included. A plurality of single-core optical fibers for branching, in which an n-th group optically connected to the core C _n of the core C _n is bundled in the same arrangement at the entrance end and the exit end;
An optical filter that selectively outputs light having different wavelengths from the first end to the Nth group of the plurality of branching single core optical fibers from the emission end;
An imaging unit that acquires an image of light that is input to the first end of the image guide and that is output from the exit ends of the first group to the Nth group of the plurality of single-core optical fibers for branching;
(M and N are integers of 2 or more, m is an integer of 1 to M, and n is an integer of 1 to N). An image guide according to claim 5;
The N cores C _{1 to} C _N of the _M multi-core optical fibers F _{1 to} F _M included in this image guide are optically connected at the second end, and the n-th of each multi-core optical fiber F _m is included. A plurality of single-core optical fibers for branching, in which an n-th group optically connected to the core C _n of the core C _n is bundled in the same arrangement at the entrance end and the exit end;
An imaging unit that acquires an image of light that is input to the first end of the image guide and that is output from the exit ends of the first group to the Nth group of the plurality of single-core optical fibers for branching;
With
The optical filter selectively outputs light having different wavelengths from the first end to the Nth group of the plurality of branching single core optical fibers from the emission end.
An imaging device (where M and N are integers of 2 or more, m is an integer of 1 to M, and n is an integer of 1 to N). An image guide according to claim 6;
A light source unit that outputs illumination light and causes the illumination light to enter a second end of the specific core of each of a plurality of multi-core optical fibers included in the image guide;
An imaging unit that acquires an image of light that is input to the first end of a core other than the specific core of each of the plurality of multi-core optical fibers and output from the second end;
An imaging apparatus comprising: The imaging unit is
An infrared reflection spectrum acquisition means for acquiring the intensity of a three-dimensional infrared reflection spectrum consisting of a surface position and a wavelength direction from a biological tissue based on an image of light output from the second end of the image guide;
Based on the infrared reflection intensity obtained by the infrared reflection spectrum acquisition means, calculation means for identifying normality / abnormality of the biological tissue;
The imaging device according to claim 8, wherein the imaging device includes: An image guide according to claim 4;
A light source unit that irradiates an object with illumination light and causes reflected light from the object to enter the first end of the specific core of each of a plurality of multi-core optical fibers included in the image guide;
An imaging unit that receives the reflected light emitted from the second end of the image guide and analyzes spectral data of an object;
An imaging apparatus comprising:

Images