JP7487602B2 - Optical Waveguides for Sensors - Google Patents

Description

The present invention relates to an optical waveguide for a sensor.

Patent Document 1 discloses a sensing system that measures the distortion of a structure, such as a building, in order to evaluate the soundness of the structure. This sensing system includes a light source, a light receiving unit, an optical splitter, an optical filter, and a sensor. In such a sensing system, the sensor is attached to the structure, and the distortion of the structure is measured based on the amount of loss of light transmitted through the sensor.

JP 2006-010449 A

In the sensing system described in Patent Document 1, the sensor is composed of optical fiber. Therefore, the strain that can be measured by the sensor is limited to a linear area around the sensor. In view of this restriction, there is a demand for measuring strain over a wider range.

In addition, by arranging the sensors in parallel, it is possible to obtain positional information of the strain in the direction in which the sensors are arranged. However, in order to sufficiently increase the resolution of the positional information, a large number of sensors are required.

The object of the present invention is to provide an optical waveguide for a sensor that can realize a sensing system that detects mechanical or thermal changes in an adherend over a wider range or with higher resolution.

These objects can be achieved by the present invention described below in (1) to (5) .
(1) An optical waveguide for a sensor that is attached to an adherend and used in a sensing system for detecting a mechanical or thermal change in the adherend, comprising:
An input core portion;
An output core portion;
a first sensing core portion and a second sensing core portion arranged in parallel with each other;
a branching portion that branches the incident core portion and connects the first sensing core portion and the second sensing core portion;
a coupling portion that joins the first sensing core portion and the second sensing core portion to connect them to the emission core portion;
At least one unit core portion having
The optical waveguide for a sensor , wherein the first sensing core portion and the second sensing core portion have different diameters .

(2) The unit core portion is
a third sensing core portion parallel to the first sensing core portion and the second sensing core portion;
The optical waveguide for a sensor according to (1) above, wherein the diameter of the third sensing core portion is larger than the sum of the diameters of the first sensing core portion and the second sensing core portion.

(3) An optical waveguide for a sensor that is attached to an adherend and used in a sensing system that detects a mechanical or thermal change in the adherend, comprising:
An input core portion;
An output core portion;
a first sensing core portion and a second sensing core portion arranged in parallel with each other;
a branching portion that branches the incident core portion and connects the first sensing core portion and the second sensing core portion;
a coupling portion that joins the first sensing core portion and the second sensing core portion to connect them to the emission core portion;
a first attenuation section provided in the first sensing core section and configured to reduce an amount of light propagating through the first sensing core section;
1. An optical waveguide for a sensor comprising at least one unit core portion comprising :

(4) The unit core portion is
a third sensing core portion and a fourth sensing core portion arranged in parallel with the second sensing core portion;
a second attenuation section provided in the second sensing core section and configured to reduce an amount of light propagating through the second sensing core section;
a third attenuation section provided in the third sensing core section and configured to reduce an amount of light propagating through the third sensing core section;
having
The optical waveguide for a sensor described in (3) above, wherein the coupling section is configured to couple to the emission core section the amount of light after dimming by the first dimming section, the amount of light after dimming by the second dimming section, the amount of light after dimming by the third dimming section, and the amount of light propagating through the fourth sensing core section.

(5) An optical waveguide for a sensor that is attached to an adherend and used in a sensing system that detects a mechanical or thermal change in the adherend, comprising:
An input core portion;
An output core portion;
a first sensing core portion and a second sensing core portion arranged in parallel with each other;
a branching portion that branches the incident core portion and connects the first sensing core portion and the second sensing core portion;
a coupling portion that joins the first sensing core portion and the second sensing core portion to connect them to the emission core portion;
a first unit core portion, a second unit core portion and a third unit core portion,
the first unit core portion, the second unit core portion, and the third unit core portion are arranged in this order;
the second unit core portion has a structure in which the first sensing core portion of the second unit core portion is branched, one of the branched portions is coupled to the second sensing core portion of the first unit core portion, and the other of the branched portions is coupled to the second sensing core portion of the second unit core portion,
The third unit core portion is an optical waveguide for a sensor characterized in that it has a structure in which the first sensing core portion of the third unit core portion is branched, one of the branched portions is coupled to the second sensing core portion of the second unit core portion, and the other branched portion is coupled to the second sensing core portion of the third unit core portion.

The present invention provides an optical waveguide for a sensor that can realize a sensing system that detects mechanical or thermal changes in an adherend over a wider range or with higher position resolution.

FIG. 2 is a plan view showing the optical waveguide for the sensor according to the first embodiment. FIG. 2 is a partially enlarged perspective view of the optical waveguide for a sensor shown in FIG. 1 . 2 is a cross-sectional view for explaining a method of using the optical waveguide for a sensor shown in FIG. 1. FIG. FIG. 2 is a plan view for explaining a method of using the sensor waveguide shown in FIG. 1 . FIG. 11 is a plan view showing an optical waveguide for a sensor according to a second embodiment. FIG. 11 is a plan view showing an optical waveguide for a sensor according to a third embodiment. FIG. 13 is a plan view showing an optical waveguide for a sensor according to a fourth embodiment. 8 is a plan view for explaining a method of using the optical waveguide for the sensor shown in FIG. 7. FIG. 8 is a plan view for explaining a method of using the optical waveguide for the sensor shown in FIG. 7. FIG. FIG. 13 is a plan view showing an optical waveguide for a sensor according to a fifth embodiment. FIG. 13 is a plan view showing an optical waveguide for a sensor according to a fifth embodiment. FIG. 13 is a plan view showing an optical waveguide for a sensor according to a sixth embodiment. 13 is a plan view for explaining a method of using the optical waveguide for the sensor shown in FIG. 12. FIG.

The optical waveguide for sensors of the present invention will be described in detail below based on the preferred embodiment shown in the attached drawings.

1. First Embodiment First, an optical waveguide for a sensor according to a first embodiment will be described.

Figure 1 is a plan view showing a sensor optical waveguide according to the first embodiment. Figure 2 is a partially enlarged perspective view of the sensor optical waveguide shown in Figure 1. Figure 3 is a cross-sectional view for explaining a method of using the sensor optical waveguide shown in Figure 1. Figure 4 is a plan view for explaining a method of using the sensor waveguide shown in Figure 1. In each figure, an X-axis, a Y-axis, and a Z-axis are set as three mutually orthogonal axes, and are indicated by arrows. The tip side of the arrow representing the Z-axis is referred to as "upper", and the base end side is referred to as "lower".

The optical waveguide 1 for a sensor according to this embodiment is a sheet-like laminate in which a first cover layer 18, a cladding layer 11, a core layer 13, a cladding layer 12, and a second cover layer 19 are laminated in this order from the bottom in FIG. 2. Each layer extends parallel to the X-Y plane. As shown in FIG. 1, an elongated core portion 14 and a plurality of side cladding portions 15 adjacent to the side of the core portion 14 are formed in the core layer 13. The elongated core portion 14 is divided into three unit core portions 10. Each unit core portion 10 extends along the Y axis and is aligned along the X axis.

The shape of the outer edge of the optical waveguide 1 for the sensor is not particularly limited, and may be a polygon such as a square or hexagon, a circle such as a perfect circle, an ellipse, or an oval, or any other shape, but in FIG. 1 it is a rectangle. And, both ends of the core portion 14 are exposed on the two end faces of the aforementioned core layer 13 that are perpendicular to the Y axis.

As shown in FIG. 3, such an optical waveguide 1 for a sensor is used to adhere to an adherend 9 with the underside of the first cover layer 18 serving as an adhesive surface 101. If necessary, an adhesive layer 2 shown in FIG. 3 may be interposed between the adhesive surface 101 and the adherend 9. The adhesive properties of the adhesive layer 2 can be used to fix the optical waveguide 1 for a sensor to the adherend 9.

The optical waveguide for sensor 1 is attached to the adherend 9 to realize a sensing system that detects mechanical or thermal changes in the adherend 9. Specifically, in this sensing system, light is continuously or intermittently incident on the core portion 14 of the optical waveguide for sensor 1 with the optical waveguide for sensor 1 attached to the adherend 9. If a mechanical or thermal change occurs in the adherend 9 while light is being incident, the amount of light emitted from the core portion 14, i.e., the amount of emitted light, changes. Mechanical or thermal changes often occur in association with an abnormality in the adherend 9. Therefore, a sensing system that can detect an abnormality in the adherend 9 can be realized by capturing the change in the amount of light emitted from the core portion 14.

Each part of the optical waveguide for the sensor 1 will be described in further detail below.
2, the side surfaces of the core 14 are surrounded by the side cladding 15 and the cladding layers 11 and 12. The refractive index of the core 14 is higher than the refractive indexes of the side cladding 15 and the cladding layers 11 and 12. This allows light to be confined in the core 14 and propagated therethrough.

In the core layer 13, the refractive index distribution in the plane perpendicular to the optical path of the core portion 14 may be any distribution, for example, a so-called step index (SI) type distribution in which the refractive index changes discontinuously, or a so-called graded index (GI) type distribution in which the refractive index changes continuously.

The cross-sectional shape of the core portion 14 in the Y-Z plane, i.e., the transverse cross-sectional shape of the core portion 14, is not particularly limited, but examples include circles such as perfect circles, ellipses, and ovals, polygons such as triangles, squares, pentagons, and hexagons, and other irregular shapes.

The average thickness of the core layer 13 is not particularly limited, but is preferably about 1 to 200 μm, more preferably about 5 to 100 μm, and even more preferably about 10 to 70 μm. This ensures the optical characteristics and mechanical strength required for the core portion 14.

Examples of materials (main materials) constituting the core layer 13 include various resin materials such as acrylic resins, methacrylic resins, polycarbonates, polystyrenes, cyclic ether resins such as epoxy resins and oxetane resins, polyamides, polyimides, polybenzoxazoles, polysilanes, polysilazanes, silicone resins, fluorine resins, polyurethanes, polyolefin resins, polybutadiene, polyisoprene, polychloroprene, polyesters such as PET and PBT, polyethylene succinate, polysulfones, polyethers, and cyclic olefin resins such as benzocyclobutene resins and norbornene resins. In addition, composite materials that combine materials with different compositions are also used as resin materials. In addition, in this specification, the "main material" refers to a material that accounts for 50% or more by mass of the constituent materials, and preferably a material that accounts for 70% or more by mass.

The average thickness of each of the cladding layers 11 and 12 is preferably about 1 to 200 μm, more preferably about 3 to 100 μm, and even more preferably about 5 to 60 μm, so that the optical properties and mechanical strength required for the cladding layers 11 and 12 are ensured.

The main material of the clad layers 11 and 12 is appropriately selected from the materials listed above as the constituent materials of the core layer 13.

Note that the clad layers 11 and 12 may be provided as necessary, and may be omitted. In this case, for example, if the core layer 13 is exposed to the outside air (air), the outside air functions as the clad layers 11 and 12.

The optical waveguide 1 for a sensor according to this embodiment has a cladding layer 11 provided between the core layer 13 and the first cover layer 18, and a cladding layer 12 provided between the core layer 13 and the second cover layer 19, so that a stable refractive index difference can be formed and maintained between the core portion 14 and its outside. This makes it possible to further increase the transmission efficiency of the core portion 14.

Either or both of the cladding layers 11 and 12 may be integral with the side cladding portion 15.

1.3 Cover Layer The first cover layer 18 is provided on the lower surface of the cladding layer 11. The second cover layer 19 is provided on the upper surface of the cladding layer 12. By providing such first cover layer 18 and second cover layer 19, the core layer 13 and the cladding layers 11 and 12 can be protected, and a decrease in the transmission efficiency of the core section 14 caused by the external environment, etc. can be suppressed.

The average thickness of the first cover layer 18 and the second cover layer 19 is not particularly limited, but is preferably about 1 to 200 μm, more preferably about 3 to 100 μm, and even more preferably about 5 to 50 μm.

The first cover layer 18 and the second cover layer 19 may have the same configuration as each other or different configurations. For example, the first cover layer 18 and the second cover layer 19 may have the same average thickness as each other or different average thicknesses. At least one of the first cover layer 18 and the second cover layer 19 may be provided as necessary, and may be omitted.

The main material of the first cover layer 18 and the second cover layer 19 may be, for example, a material containing various resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene, polyolefins such as polypropylene, polyimide, polyamide, etc.

Of these, the main material of the first cover layer 18 and the second cover layer 19 is preferably a polyimide resin. Polyimide resin has a relatively high elastic modulus and a high thermal decomposition temperature, and therefore has sufficient durability against external forces and the external environment.

The constituent materials of the first cover layer 18 and the second cover layer 19 may contain fillers, antioxidants, UV absorbers, colorants, storage stabilizers, plasticizers, lubricants, anti-deterioration agents, antistatic agents, etc., as necessary. By adding fillers, the thermal expansion coefficients of the first cover layer 18 and the second cover layer 19 can be adjusted.

1.4 Adhesive Layer The adhesive layer 2 shown in Fig. 3 adheres the sensor optical waveguide 1 to the adherend 9 when the sensor optical waveguide 1 is attached to the adherend 9. The adhesive layer 2 may be provided on the adherend 9, but may be provided in advance on the sensor optical waveguide 1 side as shown in Fig. 3. That is, the sensor optical waveguide 1 may include an uncured adhesive layer 2 provided on the lower surface of the first cover layer 18. This allows the sensor optical waveguide 1 to be attached to the adherend 9 efficiently.

Examples of adhesives that make up the adhesive layer 2 include acrylic adhesives, urethane adhesives, silicone adhesives, and epoxy adhesives, as well as various types of polyester-based and modified olefin-based hot melt adhesives.

The uncured adhesive layer 2 may be in a liquid, solid or semi-solid uncured state, or may be in a state where the curing reaction is partially in progress. The curing principle of the adhesive layer 2 may be thermosetting or photocuring. Furthermore, the uncured adhesive layer 2 may be provided on the entire underside of the first cover layer 18, or may be provided on only a portion of it. The thickness of the adhesive layer 2 after curing is not particularly limited, but is preferably 1 to 100 μm, and more preferably 5 to 60 μm.

1 has three unit core portions 10. In FIG. 1, the three unit core portions 10 are referred to as unit core portions 10a, 10b, and 10c. The unit core portion 10a will be representatively described below, but this description is similar for the unit core portions 10b and 10c, so the description will be omitted.

The unit core portion 10a has a pattern in which it branches into four parts along the way and then recombines into one. Specifically, the unit core portion 10a shown in FIG. 1 has an input core portion 141, an output core portion 142, and a first sensing core portion 143, a second sensing core portion 144, a third sensing core portion 145, and a fourth sensing core portion 146 that are arranged in parallel with one another. In the following description, these four may be collectively referred to as the "first sensing core portion 143, etc.".

The length of the first sensing core portion 143, etc. is not particularly limited, but is, for example, about 1 cm or more and 500 m or less, and more preferably about 5 cm or more and 100 m or less.

The unit core section 10a also has a branch section 16 and a coupling section 17. The branch section 16 branches the input core section 141 and connects it to the first sensing core section 143 and the like. The coupling section 17 couples the first sensing core section 143 and the like and connects it to the output core section 142.

In the unit core section 10a described above, when light enters from the incident surface 1410 of the incident core section 141, it is distributed into four by the branching section 16, and the distributed light propagates through the first sensing core section 143, etc. The distributed light is then mixed back into one by the coupling section 17, and the mixed light is emitted from the exit surface 1420 of the exit core section 142. With this configuration, the optical path can be expanded over a wider range, and the sensing area of the sensing system can be easily expanded.

Figure 4 is a plan view of the sensor optical waveguide 1 attached to the adherend 9 shown in Figure 3 when viewed from above. By being attached to the adherend 9, the sensor optical waveguide 1 is sensitive to the mechanical or thermal influence of the surface of the adherend 9. When, for example, a crack or the like occurs on the surface of the adherend 9, the sensor optical waveguide 1 is deformed accordingly, such as elongation, distortion, bending, or breakage. Hereinafter, these deformations are omitted and simply referred to as "breakage". Figure 4 shows, as an example, a state in which a crack in the adherend 9 progresses to the sensor optical waveguide 1 and a part of the first sensing core portion 143 of the unit core portion 10a is broken. Since this break portion 1430 is a gap, the light propagating through the first sensing core portion 143 is blocked by the break portion 1430. As a result, the light propagating through the first sensing core portion 143 cannot propagate to the coupling portion 17. Therefore, the amount of light emitted from the emission surface 1420 (amount of emitted light) is reduced compared to normal times.

As an example, consider a case where light is incident on each of unit core portions 10a, 10b, and 10c with a light quantity of 100, and is equally distributed to four at each branch portion 16. In the following, various losses are not taken into consideration. The same applies to other embodiments.

In the unit core parts 10b and 10c, since no breakage or the like has occurred, the emitted light amount is also 100. This emitted light amount is the normal emitted light amount not only in the unit core parts 10b and 10c but also in the unit core part 10a. In each figure, the numerical value of the light amount is indicated by a square. In the unit core part 10a, the light propagating through the first sensing core part 143 is blocked by the break part 1430. Therefore, the light amount is reduced by 25, and the emitted light amount is 75. Therefore, it is possible to detect that the light amount of the unit core part 10a is smaller than that of the unit core parts 10b and 10c. This makes it possible to detect that some mechanical or thermal change has occurred at the position of the adherend 9 corresponding to the unit core part 10a. As a result, it is possible to detect, for example, that an abnormality has occurred in the adherend 9.

In the above example, all of the light quantity 25 is lost at the broken portion 1430, but depending on the abnormal mode of the adherend 9, it is possible that only a portion of the light quantity 25 is lost. Therefore, by understanding the relationship between the amount of reduction in the emitted light quantity and the abnormal mode in advance, it becomes possible to estimate not only the position of the abnormality but also the abnormal mode.

On the other hand, if the fractured portion 1430 extends not only to the first sensing core portion 143 but also to the second sensing core portion 144, the emitted light amount will be 50. By capturing this change in the emitted light amount, it is possible to estimate the size of the area where the abnormality is occurring.

The optical waveguide for sensor 1 can detect not only mechanical changes such as cracks that occur in the adherend 9, but also thermal changes such as heat generation. In other words, if an event occurs in the adherend 9 that can change the amount of light propagating through the optical waveguide for sensor 1, the sensing system can detect it. Examples of mechanical changes include cracks, expansion/contraction, protrusions, depressions, etc. Also, examples of thermal changes include heat generation and endotherm.

The unit core section 10 has been described above, but its configuration is not limited to the above. For example, the number of branches in the branch section 16 is not limited to four, and may be two or three, or five or more. The distribution ratios in the branch sections 16 are not limited to equal distribution, and may be different from each other. Furthermore, the number of unit core sections 10 in the core layer 13 is not limited to three, and may be one or two, or four or more.

In addition, the first sensing core parts 143 and the like shown in the figure all extend straight, but they may be bent along the way, may branch out, or may intersect with each other.

Furthermore, only the portion of the optical waveguide 1 for the sensor that corresponds to the first sensing core portion 143, etc., may be adhered to the adherend 9, and the remaining portion may not be adhered.

The optical waveguide 1 for the sensor may also include an optical path conversion section such as a mirror that converts the optical path of the incident core section 141, an optical path conversion section such as a mirror that converts the optical path of the emission core section 142, and a connector that is attached near the incident core section 141 or the emission core section 142.

Furthermore, the optical waveguide 1 for the sensor may have a multilayer structure in which multiple core layers 13 are stacked.

As described above, the optical waveguide 1 for a sensor according to this embodiment is an optical waveguide that is attached to an adherend 9 and is used in a sensing system that detects mechanical or thermal changes in the adherend 9. The optical waveguide 1 for a sensor has at least one unit core portion 10. This unit core portion 10 includes an incident core portion 141, an emission core portion 142, a first sensing core portion 143 and a second sensing core portion 144 that are parallel to each other, a branch portion 16, and a coupling portion 17. The branch portion 16 branches the incident core portion 141 and connects it to the first sensing core portion 143 and the second sensing core portion 144. The coupling portion 17 joins the first sensing core portion 143 and the second sensing core portion 144 and connects them to the emission core portion 142.

With this configuration, the unit core portion 10 has a branch portion 16 and spreads over a wide range, so that if a break occurs in the first sensing core portion 143 or the second sensing core portion 144, it can be detected by a change in the amount of emitted light. Therefore, by attaching the optical waveguide 1 for the sensor to the adherend 9, a sensing system can be realized that can detect mechanical or thermal changes in the adherend 9 over a wider range. In particular, by providing the branch portion 16, even a single set of light-emitting portion and light-receiving portion can detect abnormalities in the adherend 9 over a wider range, which contributes to simplifying the structure of the sensing system and reducing costs.

1.6 Sensing System Although not shown, the sensing system includes a light emitting unit that emits light, a light receiving unit that receives light, and a control unit that outputs a detection result based on the amount of received light.

Examples of the light emitting portion include a semiconductor laser, a gas laser, and a light emitting diode.
The light receiving portion may be, for example, a photodiode or a phototransistor.

The control unit outputs the detection result based on the amount of received light. Such a control unit is composed of, for example, a device equipped with a processor, memory, and an external interface, which are connected to each other via an internal bus. The control unit operates by executing a program stored in the memory with the processor. Examples of the operation include an operation to estimate and notify the presence or absence of an abnormality in the adherend 9 and the details of the abnormality based on the relationship between the amount of decrease in the amount of received light stored in the memory and changes that have occurred in the adherend 9 in the past.

The sensor optical waveguide 1 may be connected to the light emitting section or light receiving section by an optical fiber. In this case, the control unit housing the light emitting section, light receiving section, and control section can be installed farther away from the sensor optical waveguide 1. This makes it possible to place the sensor optical waveguide 1 in a place where it is difficult to install a control unit, for example, in a very narrow place. In this case, the sensor optical waveguide 1 may be connected to the optical fiber by an optical connector, or may be directly connected using an adhesive or the like.

2. Second Embodiment Next, an optical waveguide for a sensor according to a second embodiment will be described.
FIG. 5 is a plan view showing an optical waveguide for a sensor according to the second embodiment.

The second embodiment will be described below, focusing on the differences from the first embodiment and omitting a description of similar points. Note that in FIG. 5, the same reference numerals as those previously described are used for configurations similar to those of the first embodiment.

The optical waveguide 1A for the sensor shown in FIG. 5 is similar to the optical waveguide 1 for the sensor shown in FIG. 1, except that the configuration of the branching section 16 and the coupling section 17 is different.

In the branching section 16 shown in FIG. 1, the light propagating through the incident core section 141 is distributed into four through one branch point. In contrast, in the branching section 16 shown in FIG. 5, the light is distributed into four through three branch points 16a, 16b, and 16b. Specifically, the incident core section 141 branches into two at the branch point 16a, and further branches into two each at the two branch points 16b and 16b. By having multiple branch points in this way, the branching loss in the branching section 16 can be reduced compared to the first embodiment. If the branching loss can be reduced, the decrease in the level of the emitted light is suppressed, and the decrease in the amount of emitted light can be detected more accurately.

In addition, in the coupling section 17 shown in FIG. 5, the light is mixed into one through three coupling points 17a, 17b, and 17b. Specifically, the first sensing core section 143 and the second sensing core section 144 are coupled together at coupling point 17b, and similarly, the third sensing core section 145 and the fourth sensing core section 146 are coupled together at coupling point 17b. The core sections 14, 14 extending from the two coupling points 17b, 17b are coupled together at coupling point 17a. By having multiple coupling points in this way, the coupling loss in the coupling section 17 can be reduced. If the coupling loss can be reduced, the decrease in the level of the emitted light is suppressed, and the reduction in the amount of emitted light can be detected more accurately.

The second embodiment described above also provides the same effects as the previous embodiment.

3. Third Embodiment Next, an optical waveguide for a sensor according to a third embodiment will be described.
FIG. 6 is a plan view showing an optical waveguide for a sensor according to the third embodiment.

The third embodiment will be described below, focusing on the differences from the first embodiment and omitting a description of similar points. Note that in FIG. 6, the same reference numerals as those previously described are used for configurations similar to those of the first embodiment.

The optical waveguide 1B for the sensor shown in FIG. 6 is similar to the optical waveguide 1 for the sensor shown in FIG. 1, except that the configuration of the branching section 16 and the coupling section 17, such as the first sensing core section 143, is different.

In the sensor optical waveguide 1 shown in FIG. 1 described above, the light propagating through the incident core portion 141 is equally divided into four at the branch portion 16. In contrast to this, in the sensor optical waveguide 1B shown in FIG. 6, the distribution ratios at the branch portion 16 are not equal but are different from each other. Specifically, the branch portion 16 is configured so that the distribution ratio for the first sensing core portion 143 is 10, the distribution ratio for the second sensing core portion 144 is 30, the distribution ratio for the third sensing core portion 145 is 60, and the distribution ratio for the fourth sensing core portion 146 is 120.

6, the widths of the first branch 1601 connected to the first sensing core unit 143, the second branch 1602 connected to the second sensing core unit 144, the third branch 1603 connected to the third sensing core unit 145, and the fourth branch 1604 connected to the fourth sensing core unit 146 are set to widths according to the above-mentioned distribution ratio. Also, the widths of the first sensing core unit 143 following the first branch 1601, the second sensing core unit 144 following the second branch 1602, the third sensing core unit 145 following the third branch 1603, and the fourth sensing core unit 146 following the fourth branch 1604 are set to widths according to the above-mentioned distribution ratio. In other words, the ratio of the width of the first sensing core portion 143 to the width of the second sensing core portion 144 to the width of the third sensing core portion 145 to the width of the fourth sensing core portion 146 is set to 10:30:60:120.

By setting the width in this way, the amount of light propagating through the first sensing core portion 143, the second sensing core portion 144, the third sensing core portion 145, and the fourth sensing core portion 146 will have a difference according to the distribution ratio. For this reason, for example, when a break occurs in the first sensing core portion 143 as shown in FIG. 4, the amount of light emitted will decrease by 10/(10+30+60+120) ≒ 4.5. This decrease in the amount of emitted light is different from the decrease in the amount of emitted light when a break occurs in the second sensing core portion 144, the decrease in the amount of emitted light when a break occurs in the third sensing core portion 145, and the decrease in the amount of emitted light when a break occurs in the fourth sensing core portion 146. That is, in the optical waveguide 1B for the sensor shown in FIG. 6, the first sensing core portion 143, etc. each have their own decrease in the amount of emitted light. Therefore, by detecting the width of the reduction in the amount of emitted light, it is possible to detect not only that a break has occurred in the unit core portion 10a, but also which of the first sensing core portions 143 and the like included in the unit core portion 10a has been broken. Therefore, in this embodiment, it is possible to realize an optical waveguide 1B for a sensor that can identify the position where an abnormality has occurred in the adherend 9 with higher position resolution.

As described above, in order to provide the first sensing core unit 143 and the like with a specific reduction in the amount of emitted light, the distribution ratio may be set to satisfy, for example, the following three elements:

(a) The distribution ratios are made different between the sensing cores. (b) The sum of two or more arbitrarily selected distribution ratios does not match any of the remaining distribution ratios. (c) The sum of two or more arbitrarily selected distribution ratios does not match any of the remaining two or more distribution ratios.

On the other hand, in this embodiment, the width of each of the first sensing core units 143, etc. is also set to a width according to the distribution ratio described above. This makes it possible to prevent the transmission loss of the first sensing core unit 143, etc. from affecting the distribution ratio described above. In other words, it is possible to prevent the distribution ratio set in the branch unit 16 from being shifted due to the transmission loss of the first sensing core unit 143, etc.

In this embodiment, the width of the branch path and the sensing core section is set according to the distribution ratio, but depending on the cross-sectional shape of the branch path and the sensing core section, the diameter, which is a concept that includes the width, may be set according to the distribution ratio.

As described above, in the optical waveguide for sensor 1B according to this embodiment, at least the first sensing core portion 143 and the second sensing core portion 144 have different diameters. This allows each sensing core portion to have a unique width of reduction in the amount of emitted light. As a result, by detecting the width of reduction in the amount of emitted light, it becomes possible to detect which sensing core portion has been broken or otherwise damaged. Therefore, by using the optical waveguide for sensor 1B, a sensing system can be realized that can identify the position where an abnormality has occurred in the adherend 9 in an area narrower than the unit core portion 10. In other words, the optical waveguide for sensor 1B contributes to the realization of a sensing system with higher position resolution for detecting abnormalities in the adherend 9.

The optical waveguide 1B for the sensor according to this embodiment also has at least a third sensing core portion 145 that is parallel to the first sensing core portion 143 and the second sensing core portion 144. The diameter of the third sensing core portion 145 is greater than the sum of the diameters of the first sensing core portion 143 and the second sensing core portion 144.

According to this configuration, even when there are three sensing core parts, each sensing core part can be given its own reduction in the amount of emitted light. As a result, even when there are three sensing core parts, it is possible to detect which sensing core part has been broken or otherwise damaged. In other words, it is possible to realize a sensing system that can identify the position where an abnormality has occurred in the adherend 9 over a wider range and with higher position resolution.
In the third embodiment as described above, the same effects as those of the above-described embodiments can be obtained.

4. Fourth Embodiment Next, an optical waveguide for a sensor according to a fourth embodiment will be described.

Figure 7 is a plan view showing a sensor optical waveguide according to the fourth embodiment. Figures 8 and 9 are plan views each for explaining a method of using the sensor optical waveguide shown in Figure 7.

The fourth embodiment will be described below, focusing on the differences from the first embodiment and omitting a description of similar points. Note that in FIG. 7, the same reference numerals as those previously described are used for configurations similar to those of the first embodiment.

The optical waveguide 1C for a sensor shown in FIG. 7 is similar to the optical waveguide 1 for a sensor shown in FIG. 1, except that the number of unit core portions 10 and the number of distributions in the branch portion 16 are different, and a first light-attenuating portion 31 is added.

The optical waveguide 1C for the sensor shown in FIG. 7 has four unit core portions 10, namely, unit core portions 10a, 10b, 10c, and 10d.

In the branching section 16 shown in FIG. 7, the light is equally divided into two. The optical waveguide for the sensor 1C also includes a first attenuation section 31 provided in the first sensing core section 143. Specifically, the first attenuation section 31 shown in FIG. 7 has an attenuation branching section 311 provided at the end of the first sensing core section 143 and an attenuation core section 312 extending from the attenuation branching section 311. The attenuation branching section 311 branches the end section of the first sensing core section 143 into two, one of which is connected to the coupling section 17, and the other is connected to the attenuation core section 312. The attenuation core section 312 shown in FIG. 7 does not reach the end face of the core layer 13 and is interrupted halfway. Note that the attenuation core section 312 may reach the end face of the core layer 13 as long as it is not connected to the light receiving section. Additionally, the coupling section 17 shown in FIG. 7 has a first coupling core section 171 that connects the light-attenuating branch section 311 and the emission core section 142.

The light propagating through the first sensing core section 143 is divided equally into two by the light-attenuating branch section 311. One of the divided lights is guided to the first coupled core section 171, and the other is guided to the light-attenuating core section 312. The light guided to the first coupled core section 171 is mixed with the light propagating through the second sensing core section 144 and is emitted from the emission core section 142. The light guided to the light-attenuating core section 312 is diffused at the end. Therefore, the first light-attenuating section 31 has the function of reducing the amount of light distributed to the light-attenuating core section 312.

Figure 7 illustrates the case where light with a light quantity of 100 is incident on the unit core portion 10a. The incident light is equally divided into two by the branching portion 16, so that a light quantity of 50 is distributed to each of the first sensing core portion 143 and the second sensing core portion 144. The light distributed to the first sensing core portion 143 is then equally divided into two by the light-attenuating branching portion 311, so that a light quantity of 25 is distributed to each of the first coupled core portion 171 and the light-attenuating core portion 312. As a result, the emitted light quantity is 75. This light quantity is the normal emitted light quantity.

Figure 8 is a plan view showing the optical waveguide for sensor 1C attached to the adherend 9 (not shown). When a change occurs on the surface of the adherend 9, a break 1430, for example, as shown in Figure 8, occurs in the optical waveguide for sensor 1 accordingly. Since this break 1430 is a gap, the light propagating through the first sensing core portion 143 is blocked by the break 1430. As a result, the amount of emitted light in the unit core portion 10a decreases compared to normal. Specifically, since 25 light amounts are lost, the amount of emitted light becomes 50. Therefore, it is possible to detect that the amount of light in the unit core portion 10a is less than that in the unit core portions 10b, 10c, and 10d. Moreover, since the reduction in the amount of emitted light is 25, it is possible to detect that the break 1430 has occurred in the first sensing core portion 143, not in the second sensing core portion 144. If the fracture 1430 were to occur in the second sensing core 144, the amount of emitted light would be 25, and the reduction in the amount of emitted light would be 50. Therefore, by using the optical waveguide 1C for the sensor, it is possible to detect the occurrence of some mechanical or thermal change at a position on the adherend 9 that corresponds to the first sensing core 143.

Figure 9 is a diagram for explaining the case where a break portion 1431 of a different mode from break portion 1430 occurs. The break portion 1431 shown in Figure 9 occurs so as to straddle the second sensing core portion 144 of unit core portion 10a and the first sensing core portion 143 of unit core portion 10b. As a result, the amount of emitted light from unit core portion 10a is 25, and the amount of emitted light from unit core portion 10b is 50. Therefore, based on the amount of emitted light, it is possible to identify that break portion 1431 has occurred in the second sensing core portion 144 of unit core portion 10a and the first sensing core portion 143 of unit core portion 10b.

As described above, the optical waveguide 1C for the sensor according to this embodiment has a first attenuation section 31 that is provided in the first sensing core section 143 and reduces the amount of light propagating through the first sensing core section 143.

With this configuration, even if the distribution ratio at the branch section 16 is equal, the extent of the decrease in the amount of emitted light when a break 1430 occurs can be made different between the first sensing core section 143 and the second sensing core section 144. Therefore, it becomes possible to identify whether the break 1430 has occurred in the first sensing core section 143 or the second sensing core section 144 based on the amount of emitted light.

In addition, since precise control of the distribution ratio of the branching section 16 can be difficult in manufacturing, if the distribution ratio of the branching section 16 is acceptable as an equal distribution, the manufacturing difficulty can be reduced.

Therefore, such an optical waveguide for a sensor 1C is easy to manufacture and makes it possible to realize a sensing system that can identify the position, size, etc. of an abnormality occurring in the adherend 9.
In the fourth embodiment as described above, the same effects as those of the above-described embodiments can be obtained.

5. Fifth Embodiment Next, an optical waveguide for a sensor according to a fifth embodiment will be described.

Figures 10 and 11 are plan views showing the optical waveguide for a sensor according to the fifth embodiment.

The fifth embodiment will be described below, focusing on the differences from the second embodiment and omitting a description of similar points. Note that in Figures 10 and 11, configurations similar to those in the second embodiment are given the same reference numerals as previously described.

The optical waveguide 1D for the sensor shown in Figures 10 and 11 has a first attenuation section 31, a second attenuation section 32, and a third attenuation section 33.

As described above, the first attenuation section 31 has an attenuation branch section 311 provided at the end of the first sensing core section 143, and an attenuation core section 312 extending from the attenuation branch section 311. The attenuation branch section 311 branches the first sensing core section 143 into two, one of which is connected to the coupling section 17, and the other is connected to the attenuation core section 312. The attenuation core section 312 shown in Figures 10 and 11 is not connected to the light receiving section. Note that the attenuation core section 312 may reach the end face of the core layer 13 as long as it is not connected to the light receiving section.

As shown in Figs. 10 and 11, the second attenuation section 32 has an attenuation branch section 321 provided at the end of the second sensing core section 144, and an attenuation core section 322 extending from the attenuation branch section 321. The attenuation branch section 321 branches the second sensing core section 144 into two, one of which is connected to the coupling section 17, and the other is connected to the attenuation core section 322. The attenuation core section 322 shown in Figs. 10 and 11 is not connected to the light receiving section. Note that the attenuation core section 322 may reach the end face of the core layer 13 as long as it is not connected to the light receiving section.

As shown in Figs. 10 and 11, the third attenuation section 33 has an attenuation branch section 331 provided at the end of the third sensing core section 145, and an attenuation core section 332 extending from the attenuation branch section 331. The attenuation branch section 331 branches the third sensing core section 145 into two, one of which is connected to the coupling section 17, and the other is connected to the attenuation core section 332. The attenuation core section 332 shown in Figs. 10 and 11 is not connected to the light receiving section. Note that the attenuation core section 332 may reach the end face of the core layer 13 as long as it is not connected to the light receiving section.

The coupling portion 17 shown in Figures 10 and 11 also includes a first coupled core portion 171, a second coupled core portion 172, and a third coupled core portion 173.

The first coupled core section 171 couples the first sensing core section 143 and the second sensing core section 144 via the first attenuation section 31. The second coupled core section 172 couples the second sensing core section 144 and the third sensing core section 145 via the second attenuation section 32. The third coupled core section 173 couples the third sensing core section 145 and the fourth sensing core section 146 via the third attenuation section 33. In this way, the coupling section 17 couples the first sensing core section 143 etc. and connects them to the emission core section 142.

Figure 11 illustrates the case where light is incident on the unit core portion 10 at a light intensity of 100.

The incident light is equally divided into four parts by the branching section 16, so that the first sensing core section 143 and the like are each distributed with an amount of light of 25. The light distributed to the first sensing core section 143 is equally divided into two parts by the light-attenuating branching section 311, so that the first coupled core section 171 and the light-attenuating core section 312 are each distributed with an amount of light of 12.5.

The light distributed to the first coupled core section 171 is mixed with the light distributed to the second sensing core section 144. Therefore, in the second sensing core section 144, the amount of light between the first coupled core section 171 and the second coupled core section 172 is 25 + 12.5 = 37.5. This amount of light is further divided equally into two by the light-attenuating branch section 321, so that an amount of light of 18.75 each is distributed to the second coupled core section 172 and the light-attenuating core section 322.

The light distributed to the second coupled core section 172 is mixed with the light distributed to the third sensing core section 145. Therefore, in the third sensing core section 145, the amount of light between the second coupled core section 172 and the third coupled core section 173 is 25 + 18.75 = 43.75. This amount of light is further divided equally into two by the light-attenuating branch section 331, so that an amount of light of 21.875 is distributed each to the third coupled core section 173 and the light-attenuating core section 332.

The light distributed to the third coupled core section 173 is mixed with the light distributed to the fourth sensing core section 146 and is guided to the emission core section 142. Therefore, the amount of emitted light is 25 + 21.875 = 46.875. This amount of light is the amount of emitted light under normal conditions.

In such a sensor optical waveguide 1D, the number of light-attenuating sections through which light passes before being emitted differs between the first sensing core section 143, the second sensing core section 144, the third sensing core section 145, and the fourth sensing core section 146. Therefore, when a break occurs in each sensing core section, the width of the reduction in the amount of emitted light differs between the sensing core sections. In other words, a unique value of the width of the reduction in the amount of emitted light is given. For example, when a break occurs in the first sensing core section 143 in FIG. 11, the width of the reduction in the amount of emitted light is 3.125. Similarly, when a break occurs in the second sensing core section 144, the width of the reduction in the amount of emitted light is 6.25, when a break occurs in the third sensing core section 145, the width of the reduction in the amount of emitted light is 12.5, and when a break occurs in the fourth sensing core section 146, the width of the reduction in the amount of emitted light is 25. Therefore, by detecting the amount of reduction in the amount of emitted light, it is possible to detect the location, size, etc. of the abnormality occurring in the adherend 9.

As described above, the optical waveguide 1D for the sensor according to this embodiment has the first sensing core portion 143, the second sensing core portion 144, the third sensing core portion 145, and the fourth sensing core portion 146, which are arranged in parallel with each other. The optical waveguide 1D for the sensor also has the first light attenuation portion 31, the second light attenuation portion 32, and the third light attenuation portion 33. The first light attenuation portion 31 is provided in the first sensing core portion 143 and reduces the amount of light propagating through the first sensing core portion 143. The second light attenuation portion 32 is provided in the second sensing core portion 144 and reduces the amount of light propagating through the second sensing core portion 144. The third light attenuation portion 33 is provided in the third sensing core portion 145 and reduces the amount of light propagating through the third sensing core portion 145. The coupling section 17 of the optical waveguide 1D for the sensor is configured to combine the amount of light after dimming by the first dimming section 31, the amount of light after dimming by the second dimming section 32, the amount of light after dimming by the third dimming section 33, and the amount of light propagating through the fourth sensing core section 146, and couple them to the emission core section 142.

According to this configuration, even when there are four sensing cores, when a break occurs in each sensing core, the amount of reduction in the amount of emitted light can be made different between the sensing cores. Therefore, by detecting the amount of reduction in the amount of emitted light, it is possible to identify the sensing core where the break has occurred. Therefore, by using the optical waveguide for sensor 1D, it is possible to realize a sensing system that can identify the position, size, etc. of an abnormality, etc., occurring in the adherend 9.
In the fifth embodiment as described above, the same effects as those of the previous embodiments can be obtained.

6. Sixth Embodiment Next, an optical waveguide for a sensor according to a sixth embodiment will be described.
Fig. 12 is a plan view showing an optical waveguide for a sensor according to a sixth embodiment Fig. 13 is a plan view for explaining a method of using the optical waveguide for a sensor shown in Fig. 12 .

The sixth embodiment will be described below, focusing on the differences from the fourth embodiment and omitting a description of similar points. Note that in Figures 12 and 13, configurations similar to those of the fourth embodiment are given the same reference numerals as previously described.

The optical waveguide for a sensor 1E shown in FIG. 12 is similar to the optical waveguide for a sensor 1C shown in FIG. 7, except that the number of unit core portions 10 is different and light amount adjustment portions 4B and 4C are added.

The optical waveguide for a sensor 1E shown in FIG. 12 has four unit core parts 10: a first unit core part 10A, a second unit core part 10B, a third unit core part 10C, and a fourth unit core part 10D. Note that the first unit core part 10A, the second unit core part 10B, the third unit core part 10C, and the fourth unit core part 10D are a part of a row of many unit core parts 10 lined up along the X-axis in FIG. 12. Below, the second unit core part 10B and the third unit core part 10C will be described as representatives, and a description of the first unit core part 10A and the fourth unit core part 10D, which have a similar configuration, will be omitted.

The second unit core part 10B has a light amount adjustment part 4B provided in the first sensing core part 143 and a coupling part 17B as the coupling part 17 described above. Specifically, the light amount adjustment part 4B shown in FIG. 12 has a light amount adjustment branch part 41B provided at the end part of the first sensing core part 143 of the second unit core part 10B and a light amount adjustment core part 42B extending from the light amount adjustment branch part 41B. The light amount adjustment branch part 41B branches the first sensing core part 143 of the second unit core part 10B into two. The light amount adjustment core part 42B has one branched part coupled to the second sensing core part 144 of the first unit core part 10A. The coupling part 17B also has a coupling core part 171B, and the coupling core part 171B has the other branched part coupled to the second sensing core part 144 of the second unit core part 10B.

The third unit core part 10C includes a light amount adjustment part 4C provided in the first sensing core part 143 and a coupling part 17C as the coupling part 17 described above. Specifically, the light amount adjustment part 4C shown in FIG. 12 includes a light amount adjustment branch part 41C provided at the end of the first sensing core part 143 of the third unit core part 10C and a light amount adjustment core part 42C extending from the light amount adjustment branch part 41C. The light amount adjustment branch part 41C branches the first sensing core part 143 of the third unit core part 10C into two. The light amount adjustment core part 42C has one branched part coupled to the second sensing core part 144 of the second unit core part 10B. The coupling part 17C also includes a coupling core part 171C, and the coupling core part 171C has the other branched part coupled to the second sensing core part 144 of the third unit core part 10C.

Figure 12 illustrates the case where light with a light quantity of 100 is incident on each of the first unit core part 10A, the second unit core part 10B, the third unit core part 10C, and the fourth unit core part 10D. The incident light is equally divided into two by the branching part 16, so that a light quantity of 50 is distributed to each of the first sensing core part 143 and each of the second sensing core part 144.

For example, in the second unit core portion 10B, the light amount of 50 is further divided equally into two by the light amount adjustment branch portion 41B, so that the light amount of 25 is distributed to each of the combined core portion 171B and the light amount adjustment core portion 42B.

In addition, in the third unit core portion 10C, the light amount 50 is further divided equally into two by the light amount adjustment branch portion 41C, so that the light amount 25 is distributed to each of the combined core portion 171C and the light amount adjustment core portion 42C.

Then, the coupled core section 171B and the light amount adjustment core section 42C join the second sensing core section 144 of the second unit core section 10B, and are then connected to the emission core section 142. In other words, the second unit core section 10B receives an additional amount of light from the adjacent third unit core section 10C. Including this additional amount, the emission light amount of the second unit core section 10B becomes 100. This amount of light becomes the normal emission light amount of the second unit core section 10B. Similarly, the first unit core section 10A, the third unit core section 10C, and the fourth unit core section 10D also receive an additional amount of light from the adjacent unit core sections, and each of the normal emission light amounts becomes 100.

Figure 13 is a plan view showing the optical waveguide for the sensor 1E attached to an adherend 9 (not shown). When an abnormality occurs on the surface of the adherend 9, a break 1432, for example, as shown in Figure 13, occurs in the optical waveguide for the sensor 1E. Because this break 1432 is a gap, the light propagating through the second sensing core portion 144 of the second unit core portion 10B and the light propagating through the first sensing core portion 143 of the third unit core portion 10C are each blocked by the break 1432. As a result, 50 of the amount of light is lost from each.

On the other hand, under normal circumstances, as described above, a light amount of 25 is added from the first sensing core portion 143 of the third unit core portion 10C to the second sensing core portion 144 of the second unit core portion 10B via the light amount adjustment portion 4C. However, in FIG. 13, since the break portion 1432 overlaps with the first sensing core portion 143 of the third unit core portion 10C, this addition of light amount 25 is not performed. As a result, the emitted light amount of the second unit core portion 10B is 25, which is the original amount of 100 minus 75 (= 50 + 25).

In addition, because the light intensity of the first sensing core portion 143 of the third unit core portion 10C becomes 0, the light intensity of the coupled core portion 171C also decreases from the normal 25 to 0. As a result, the emitted light intensity of the third unit core portion 10C is 75, which is the original 100 minus 25.

Considering the above, in the optical waveguide 1E for the sensor shown in FIG. 13, the extent of the reduction in the amount of emitted light differs when the first sensing core portion 143 of each unit core portion 10 is broken and when the second sensing core portion 144 is broken. Therefore, based on the extent of the reduction in the amount of emitted light of each unit core portion 10, it becomes possible to identify in which of the first sensing core portion 143 and the second sensing core portion 144 of each unit core portion 10 the break portion 1432 has occurred.

In particular, when a break 1432 occurs on the first sensing core unit 143 side of each unit core unit 10, the decrease in the amount of emitted light can be detected in both of the two adjacent unit core units 10. Therefore, even if some abnormality occurs in the light receiving unit that detects the amount of emitted light of one unit core unit 10, the occurrence of the break 1432 can be detected by detecting the amount of emitted light of the other unit core unit 10. As a result, although the position resolution is somewhat reduced, robustness is improved, and the reliability of the sensing system can be improved.

Furthermore, if a fracture 1432 occurs across adjacent unit core parts 10, the reduction in the amount of emitted light is greater than in other embodiments. This makes it possible to realize a sensing system that can more reliably detect changes in the amount of emitted light.

As described above, the optical waveguide for a sensor 1E according to this embodiment has at least the first unit core part 10A, the second unit core part 10B, and the third unit core part 10C as the unit core part 10. The first unit core part 10A, the second unit core part 10B, and the third unit core part 10C are arranged in this order. The second unit core part 10B has a structure (light amount adjustment part 4B and coupling part 17B) in which the first sensing core part 143 of the second unit core part 10B is branched, one of the branched parts is coupled to the second sensing core part 144 of the first unit core part 10A, and the other branched part is coupled to the second sensing core part 144 of the second unit core part 10B. Furthermore, the third unit core part 10C has a structure (light amount adjustment part 4C and coupling part 17C) in which the first sensing core part 143 of the third unit core part 10C is branched, one of the branched parts is coupled to the second sensing core part 144 of the second unit core part 10B, and the other branched part is coupled to the second sensing core part 144 of the third unit core part 10C.

With this configuration, it is possible to identify in which of the unit core portions 10, the first sensing core portion 143 or the second sensing core portion 144, the break portion 1432 has occurred, based on the width of reduction in the amount of emitted light of each unit core portion 10. In particular, when the break portion 1432 occurs so as to straddle adjacent unit core portions 10, the width of reduction in the amount of emitted light becomes larger than in the other embodiments, and therefore the optical waveguide for sensor 1E contributes to realizing a highly reliable sensing system.
In the sixth embodiment as described above, the same effects as those of the previous embodiments can be obtained.

The optical waveguide for sensors of the present invention has been described above based on the illustrated embodiments, but the present invention is not limited to these.

For example, the optical waveguide for the sensor may further have a protective layer covering the adhesive layer. This protective layer is peeled off from the adhesive layer immediately before adhering the optical waveguide for the sensor to the adherend, making it possible to easily prepare a clean adhesive surface. This makes it possible to prevent foreign matter from being caught in the optical waveguide, and to achieve adhesion with higher adhesion. As a result, it is possible to realize an optical waveguide for the sensor that can detect abnormalities occurring in the adherend with higher sensitivity.

1 Optical waveguide for sensor 1A Optical waveguide for sensor 1B Optical waveguide for sensor 1C Optical waveguide for sensor 1D Optical waveguide for sensor 1E Optical waveguide for sensor 2 Adhesive layer 4B Light amount adjustment section 4C Light amount adjustment section 9 Adherend 10 Unit core part 10A First unit core part 10B Second unit core part 10C Third unit core part 10D Fourth unit core part 10a Unit core part 10b Unit core part 10c Unit core part 10d Unit core part 11 Cladding layer 12 Cladding layer 13 Core layer 14 Core part 15 Side cladding part 16 Branching part 16a Branching point 16b Branching point 17 Coupling part 17B Coupling part 17C Coupling part 17a Coupling point 17b Coupling point 18 First cover layer 19 Second cover layer 31 First light-attenuating part 32 Second light-attenuating part 33 Third attenuation section 41B Light amount adjusting branch section 41C Light amount adjusting branch section 42B Light amount adjusting core section 42C Light amount adjusting core section 101 Adhesive surface 141 Incident core section 142 Emitting core section 143 First sensing core section 144 Second sensing core section 145 Third sensing core section 146 Fourth sensing core section 171 First coupled core section 171B Coupled core section 171C Coupled core section 172 Second coupled core section 173 Third coupled core section 311 Attenuation branch section 312 Attenuation core section 321 Attenuation branch section 322 Attenuation core section 331 Attenuation branch section 332 Attenuation core section 1410 Incident surface 1420 Emitting surface 1430 Breaking section 1431 Breaking section 1432 Breaking section 1601 First branch path 1602 Second branch path 1603 Third branch 1604 Fourth branch

Claims (5)

An optical waveguide for a sensor that is attached to an adherend and is used in a sensing system that detects a mechanical or thermal change in the adherend, comprising:
An input core portion;
An output core portion;
a first sensing core portion and a second sensing core portion arranged in parallel with each other;
a branching portion that branches the incident core portion and connects the first sensing core portion and the second sensing core portion;
a coupling portion that joins the first sensing core portion and the second sensing core portion to connect them to the emission core portion;
At least one unit core portion having
The optical waveguide for a sensor , wherein the first sensing core portion and the second sensing core portion have different diameters . The unit core portion includes:
a third sensing core portion parallel to the first sensing core portion and the second sensing core portion;
2 . The optical waveguide for a sensor according to claim 1 , wherein a diameter of the third sensing core portion is larger than a sum of a diameter of the first sensing core portion and a diameter of the second sensing core portion. An optical waveguide for a sensor that is attached to an adherend and is used in a sensing system that detects a mechanical or thermal change in the adherend, comprising:
An input core portion;
An output core portion;
a first sensing core portion and a second sensing core portion arranged in parallel with each other;
a branching portion that branches the incident core portion and connects the first sensing core portion and the second sensing core portion;
a coupling portion that joins the first sensing core portion and the second sensing core portion to connect them to the emission core portion;
a first attenuation section provided in the first sensing core section and configured to reduce an amount of light propagating through the first sensing core section;
An optical waveguide for a sensor, comprising at least one unit core portion comprising: The unit core portion includes:
a third sensing core portion and a fourth sensing core portion arranged in parallel with the second sensing core portion;
a second attenuation section provided in the second sensing core section and configured to reduce an amount of light propagating through the second sensing core section;
a third attenuation section provided in the third sensing core section and configured to reduce an amount of light propagating through the third sensing core section;
having
4. The optical waveguide for a sensor as described in claim 3, wherein the coupling section is configured to couple to the emission core section a total of the amount of light after dimming by the first attenuation section, the amount of light after dimming by the second attenuation section, the amount of light after dimming by the third attenuation section, and the amount of light propagating through the fourth sensing core section. An optical waveguide for a sensor that is attached to an adherend and is used in a sensing system that detects a mechanical or thermal change in the adherend, comprising:
An input core portion;
An output core portion;
a first sensing core portion and a second sensing core portion arranged in parallel with each other;
a branching portion that branches the incident core portion and connects the first sensing core portion and the second sensing core portion;
a coupling portion that joins the first sensing core portion and the second sensing core portion to connect them to the emission core portion;
a first unit core portion, a second unit core portion and a third unit core portion,
the first unit core portion, the second unit core portion, and the third unit core portion are arranged in this order;
the second unit core portion has a structure in which the first sensing core portion of the second unit core portion is branched, one of the branched portions is coupled to the second sensing core portion of the first unit core portion, and the other of the branched portions is coupled to the second sensing core portion of the second unit core portion,
The third unit core portion is an optical waveguide for a sensor characterized in that it has a structure in which the first sensing core portion of the third unit core portion is branched, one of the branched portions is coupled to the second sensing core portion of the second unit core portion, and the other branched portion is coupled to the second sensing core portion of the third unit core portion .

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