JP2022029807A - Optical waveguide for sensor - Google Patents

Abstract

To provide an optical waveguide for a sensor that can realize a sensing system for detecting a thermal or mechanical change in an attachment target body with a higher position resolution in a wider range.SOLUTION: The optical waveguide for the sensor according to the present invention is used for a sensing system attached to an attachment target body to detect a thermal or mechanical change in the attachment target body. The optical waveguide has at least one unit core unit including: an incident core unit; an emission core unit; a first sensing core unit and a second sensing core unit parallel to each other; a branch unit for branching the incident core unit so as to be connected to the first sensing core unit and the second sensing core unit; and a connection unit for joining the first sensing core unit and the second sensing core unit so as to be connected to the emission core unit.SELECTED DRAWING: Figure 1

Description

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

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

Japanese Unexamined Patent Publication No. 2006-010449

In the sensing system described in Patent Document 1, the sensor is composed of an optical fiber. Therefore, the strain can be measured by the sensor only in the linear region around the sensor. In view of such restrictions, there is a demand for measuring strain in a wider range.

Further, by arranging the sensors in parallel, the position information of the distortion can be acquired in the direction in which the sensors are arranged. However, in order to sufficiently improve the resolution of position information, a large number of sensors are required.

An 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.

Such an object is achieved by the present invention of the following (1) to (6).
(1) An optical waveguide for a sensor attached to an adherend and used in a sensing system for detecting mechanical or thermal changes in the adherend.
Incident core part and
Ejecting core part and
The first sensing core part and the second sensing core part that are parallel to each other,
A branch portion that branches the incident core portion and connects to 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 and connects to the exit core portion.
An optical waveguide for a sensor, characterized by having at least one unit core portion comprising.

(2) The optical waveguide for a sensor according to (1) above, wherein the first sensing core portion and the second sensing core portion have different diameters from each other.

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

(4) The optical waveguide for a sensor according to (1) above, which is provided in the first sensing core portion and has a first dimming portion that reduces the amount of light propagating through the first sensing core portion.

(5) A third sensing core portion and a fourth sensing core portion parallel to the second sensing core portion,
A second dimming section provided in the second sensing core section and reducing the amount of light propagating through the second sensing core section.
A third dimming section provided in the third sensing core section and reducing the amount of light propagating through the third sensing core section.
Have,
The coupling portion includes 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 fourth. The optical waveguide for a sensor according to (4) above, which is configured to combine the amount of light propagating in the sensing core portion with the amount of light propagating in the emitting core portion and to be coupled to the emission core portion.

(6) The unit core portion includes 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 branches the first sensing core portion of the second unit core portion, and one after branching is coupled to the second sensing core portion of the first unit core portion, and after branching. Has a structure in which the other of the above is coupled to the second sensing core portion of the second unit core portion.
The third unit core portion branches the first sensing core portion of the third unit core portion, and one of the branches is coupled to the second sensing core portion of the second unit core portion, and after branching. The optical waveguide for a sensor according to any one of (1) to (3) above, which has a structure in which the other of the above is coupled to the second sensing core portion of the third unit core portion.

According to the present invention, there is 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 positional resolution.

It is a top view which shows the optical waveguide for a sensor which concerns on 1st Embodiment. It is a partially enlarged perspective view of the optical waveguide for a sensor shown in FIG. It is sectional drawing for demonstrating how to use the optical waveguide for a sensor shown in FIG. It is a top view for demonstrating the usage of the waveguide for a sensor shown in FIG. It is a top view which shows the optical waveguide for a sensor which concerns on 2nd Embodiment. It is a top view which shows the optical waveguide for a sensor which concerns on 3rd Embodiment. It is a top view which shows the optical waveguide for a sensor which concerns on 4th Embodiment. It is a top view for demonstrating the usage of the optical waveguide for a sensor shown in FIG. 7. It is a top view for demonstrating the usage of the optical waveguide for a sensor shown in FIG. 7. It is a top view which shows the optical waveguide for a sensor which concerns on 5th Embodiment. It is a top view which shows the optical waveguide for a sensor which concerns on 5th Embodiment. It is a top view which shows the optical waveguide for a sensor which concerns on 6th Embodiment. It is a top view for demonstrating the usage of the optical waveguide for a sensor shown in FIG.

Hereinafter, the optical waveguide for a sensor of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

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

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

The sensor optical waveguide 1 according to the present embodiment is a sheet in which the first cover layer 18, the clad layer 11, the core layer 13, the clad layer 12, and the second cover layer 19 are laminated in this order from the lower part of FIG. It is a laminated body that forms a shape. Each layer extends parallel to the XY plane. As shown in FIG. 1, a long core portion 14 and a plurality of side surface clad portions 15 adjacent to the side surface 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 arranged 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 a hexagon, a circle such as a perfect circle, an ellipse, or an oval, or any other shape. Then it is a rectangle. Then, in the core layer 13 described above, both ends of the core portion 14 are exposed on the two end faces orthogonal to the Y axis.

As shown in FIG. 3, such an optical waveguide 1 for a sensor is used so that the lower surface of the first cover layer 18 is used as an adhesive surface 101 to adhere to the adherend 9. If necessary, the adhesive layer 2 shown in FIG. 3 may be interposed between the adhesive surface 101 and the adherend 9. The optical waveguide 1 for a sensor can be fixed to the adherend 9 by utilizing the adhesiveness of the adhesive layer 2.

The optical waveguide 1 for a sensor 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 sensor optical waveguide 1 in a state where the sensor optical waveguide 1 is attached to the adherend 9. If there is a mechanical or thermal change in the adherend 9 in a state where light is incident, the amount of light emitted from the core portion 14, that is, the amount of emitted light changes. Mechanical or thermal changes often occur with anomalies in the adherend 9. Therefore, it is possible to realize a sensing system capable of detecting an abnormality in the adherend 9 by capturing a change in the amount of light emitted from the core portion 14.

Hereinafter, each part of the optical waveguide 1 for a sensor will be described in more detail.
1.1. Core layer As shown in FIG. 2, the side surface of the core portion 14 is surrounded by the side surface clad portion 15 and the clad layers 11 and 12. The refractive index of the core portion 14 is higher than that of the side clad portion 15 and the clad layers 11 and 12. As a result, light can be confined and propagated in the core portion 14.

In the core layer 13, the refractive index distribution in the plane orthogonal 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. It may be a so-called graded index (GI) type distribution in which the refractive index is continuously changed.

The cross-sectional shape of the core portion 14 by the YZ plane, that is, the cross-sectional shape of the core portion 14 is not particularly limited, but is, for example, a circle such as a perfect circle, an ellipse, an oval, a triangle, a quadrangle, a pentagon, a hexagon, or the like. Polygons and other irregular shapes can be mentioned.

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 properties and mechanical strength required for the core portion 14.

Examples of the constituent material (main material) of the core layer 13 include acrylic resin, methacrylic resin, polycarbonate, polystyrene, cyclic ether resin such as epoxy resin and oxetane resin, polyamide, polyimide, and polybenzoxazole. Polysilane, polysilazane, silicone resin, fluororesin, polyurethane, polyolefin resin, polybutadiene, polyisoprene, polychloroprene, polyester such as PET and PBT, polyethylene succinate, polysulfone, polyether, and benzocyclobutene resin. And various resin materials such as cyclic olefin-based resins such as norbornene-based resins can be mentioned. As the resin material, a composite material in which materials having different compositions are combined is also used. Further, in the present specification, the "main material" means a material which occupies 50% by mass or more of the constituent material, and preferably means a material which occupies 70% by mass or more of the constituent material.

1.2. Clad layer The average thickness of the clad 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. This ensures the optical properties and mechanical strength required for the clad layers 11 and 12.

Further, the main materials of the clad layers 11 and 12 are appropriately selected and used from the materials listed as the constituent materials of the core layer 13 described above, for example.

The clad layers 11 and 12 may be provided as needed and may be omitted. At this time, 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 sensor optical waveguide 1 according to the present embodiment is provided between the clad layer 11 provided between the core layer 13 and the first cover layer 18 and between the core layer 13 and the second cover layer 19. Since the clad layer 12 is provided, a stable refractive index difference can be formed and maintained between the core portion 14 and the outside thereof. Therefore, the transmission efficiency of the core unit 14 can be further improved.

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

1.3. Cover layer The first cover layer 18 is provided on the lower surface of the clad layer 11. The second cover layer 19 is provided on the upper surface of the clad layer 12. By providing such a first cover layer 18 and a second cover layer 19, the core layer 13 and the clad layers 11 and 12 are protected, and the decrease in the transmission efficiency of the core portion 14 due to the external environment or the like is suppressed. Can be done.

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 more preferably about 5 to 50 μm. Is even more preferable.

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

The main materials of the first cover layer 18 and the second cover layer 19 include, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyolefins such as polyethylene and polypropylene, and various resins such as polyimide and polyamide. Can be mentioned.

Of these, it is preferable that the main materials of the first cover layer 18 and the second cover layer 19 are polyimide resins, respectively. Since the polyimide resin has a relatively high elastic modulus and a high thermal decomposition temperature, it 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 include fillers, antioxidants, ultraviolet absorbers, colorants, storage stabilizers, plasticizers, lubricants, and deterioration inhibitors, as necessary. An antistatic agent or the like may be added. Of these, the coefficient of thermal expansion of the first cover layer 18 and the second cover layer 19 can be adjusted by adding a filler.

1.4. Adhesive layer The adhesive layer 2 shown in FIG. 3 adheres between the optical waveguide 1 for a sensor when it is attached to the adherend 9. The adhesive layer 2 may be provided on the adherend 9, but may be provided on the sensor optical waveguide 1 side in advance as shown in FIG. That is, the optical waveguide 1 for a sensor may include an uncured adhesive layer 2 provided on the lower surface of the first cover layer 18. As a result, the work of attaching the optical waveguide 1 for the sensor to the adherend 9 can be efficiently performed.

Examples of the adhesive constituting the adhesive layer 2 include acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, and various hot melt adhesives of polyesters and modified olefins. Be done.

The uncured adhesive layer 2 may be in a liquid state, a solid state or a semi-solid state, or may be in a state in which a curing reaction is partially progressing. Further, the curing principle of the adhesive layer 2 may be thermosetting or photocuring. Further, the uncured adhesive layer 2 may be provided on the entire lower surface of the first cover layer 18, or may be provided only on a part of the lower surface. The thickness of the adhesive layer 2 after curing is not particularly limited, but is preferably 1 to 100 μm, more preferably 5 to 60 μm.

1.5. Unit core portion As described above, the core layer 13 shown in FIG. 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. Hereinafter, the unit core portion 10a will be described as a representative, but since this description is the same for the unit core portions 10b and 10c, the description thereof will be omitted.

The unit core portion 10a has a pattern in which the unit core portion 10a is branched into four in the middle and then recombined into one. Specifically, the unit core portion 10a shown in FIG. 1 includes an incident core portion 141, an emitting core portion 142, and a first sensing core portion 143, a second sensing core portion 144, and a third sensing core portion 145 that are parallel to each other. And a fourth sensing core unit 146. In the following description, these four may be collectively referred to as "first sensing core unit 143 and the like".

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

Further, the unit core portion 10a has a branch portion 16 and a coupling portion 17. The branch portion 16 branches the incident core portion 141 and connects to the first sensing core portion 143 and the like. The coupling portion 17 connects the first sensing core portion 143 and the like to the exit core portion 142.

In the unit core portion 10a as described above, when light is incident from the incident surface 1410 of the incident core portion 141, the light is divided into four by the branch portion 16 and the distributed light propagates through the first sensing core portion 143 and the like. After that, the distributed light is mixed again at the coupling portion 17, and the mixed light is emitted from the emission surface 1420 of the emission core portion 142. According to such a configuration, the optical path can be expanded in a wider range, and the sensing area of the sensing system can be easily expanded.

FIG. 4 is a plan view of the optical waveguide 1 for a sensor attached to the adherend 9 shown in FIG. 3 when viewed from above. By being attached to the adherend 9, the optical waveguide 1 for a sensor is sensitively affected by mechanical or thermal influences on the surface of the adherend 9. When, for example, a crack or the like occurs on the surface of the adherend 9, the optical waveguide 1 for a sensor undergoes deformation such as elongation, distortion, bending, and breakage. Hereinafter, these deformations are omitted and are simply referred to as "break". FIG. 4 shows, as an example, a state in which a crack in the adherend 9 extends to the optical waveguide 1 for a sensor, and a part of the first sensing core portion 143 of the unit core portion 10a is broken. Since the broken portion 1430 is a void, the light propagating through the first sensing core portion 143 is blocked by the broken 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 (the amount of emitted light) is reduced as compared with normal times.

Here, as an example, consider a case where light is incident on each of the unit core portions 10a, 10b, and 10c with a light amount of 100, and is equally distributed to four by each branch portion 16. Hereinafter, various losses are not considered. The same applies to other embodiments.

Since no breakage or the like has occurred in the unit core portions 10b and 10c, the amount of emitted light is also 100. The amount of emitted light is the amount of emitted light in normal times not only in the unit core portions 10b and 10c but also in the unit core portion 10a. In each figure, the numerical value of the amount of light is shown by enclosing it in a square. In the unit core portion 10a, the light propagating through the first sensing core portion 143 is blocked by the breaking portion 1430. Therefore, the amount of light 25 is reduced, and the amount of emitted light becomes 75. Therefore, it can be detected that the amount of light in the unit core portion 10a is smaller than that in the unit core portions 10b and 10c. Thereby, it is possible to detect that some mechanical or thermal change has occurred in the position corresponding to the unit core portion 10a in the adherend 9. As a result, it is possible to detect that, for example, an abnormality has occurred in the adherend 9.

Further, in the above example, all of the light amount 25 is lost at the broken portion 1430, but depending on the abnormal mode of the adherend 9, only a part of the light amount 25 may be lost. Therefore, by grasping the relationship between the decrease width of the emitted light amount and the abnormal mode in advance, it is possible to estimate not only the abnormal position but also the abnormal mode.

On the other hand, when the broken portion 1430 extends not only to the first sensing core portion 143 but also to the second sensing core portion 144, the amount of emitted light is 50. By capturing such changes in the amount of emitted light, it is possible to estimate the size of the region where the abnormality has occurred.

The sensor optical waveguide 1 can capture not only mechanical changes such as cracks generated in the adherend 9 but also thermal changes such as heat generation. That is, if an event that can change the amount of light propagating through the sensor optical waveguide 1 occurs in the adherend 9, the sensing system can detect it. Mechanical changes include, for example, cracks, expansion and contraction, ridges, depressions and the like. Further, examples of the thermal change include heat generation, endothermic reaction, and the like.

Although the unit core portion 10 has been described above, the configuration thereof is not limited to the above. For example, the number of branches in the branch portion 16 is not limited to 4, and may be 2 or 3 or 5 or more. Further, the distribution ratio in the branch portion 16 is not limited to equal distribution and may be different from each other. Further, the number of unit core portions 10 included in the core layer 13 is not limited to 3, and may be 1 or 2, or 4 or more.

Further, although the first sensing core portion 143 and the like shown in the figure all extend linearly, they may be bent in the middle, may be further branched, or may intersect with each other.

Further, of the optical waveguide 1 for the sensor, only the portion corresponding to the first sensing core portion 143 and the like may be adhered to the adherend 9, and the remaining portion may not be adhered.

Further, the optical waveguide 1 for a sensor includes an optical path conversion unit such as a mirror that converts the optical path of the incident core unit 141, an optical path conversion unit such as a mirror that converts the optical path of the emission core unit 142, and the incident core unit 141 and the emission core unit 142. It may be provided with a connector or the like that can be attached in the vicinity of.

Further, the optical waveguide 1 for a sensor may have a multilayer structure in which a plurality of core layers 13 are laminated.

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

According to such a configuration, since the unit core portion 10 includes the branch portion 16 and spreads over a wide range, when the first sensing core portion 143 and the second sensing core portion 144 are broken, the amount of emitted light is increased. It can be detected by change. Therefore, by attaching the optical waveguide 1 for a sensor to the adherend 9, it is possible to realize a sensing system capable of detecting mechanical or thermal changes in the adherend 9 in a wider range. In particular, by providing the branch portion 16, the abnormality of the adherend 9 can be detected in a wider range even with one set of the light emitting portion and the light receiving portion, so that the structure of the sensing system can be simplified and the cost can be reduced. It can contribute to the conversion.

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, a control unit that outputs a detection result based on the amount of light received, and the like.

Examples of the light emitting unit include a semiconductor laser, a gas laser, a light emitting diode, and the like.
Examples of the light receiving unit include a photodiode, a phototransistor, and the like.

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 including a processor, a memory, an external interface, and the like connected to each other by an internal bus. The control unit operates by executing a program stored in the memory on the processor. As the operation content, for example, the presence or absence of an abnormality in the adherend 9 and the content are estimated based on the relationship between the decrease in the amount of received light and the change that has occurred in the adherend 9 in the past, which is stored in the memory. The operation of notifying the user can be mentioned.

It should be noted that the optical waveguide 1 for the sensor and the light emitting unit or the light receiving unit may be connected by an optical fiber. In that case, the control unit containing the light emitting unit, the light receiving unit, and the control unit can be installed farther from the optical waveguide 1 for the sensor. Therefore, the optical waveguide 1 for the sensor can be arranged in a place where it is difficult to install the control unit, for example, in a very narrow place. In this case, an optical connector may be used to connect the optical waveguide 1 for the sensor and the optical fiber, or a direct connection may be made using an adhesive or the like.

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

Hereinafter, the second embodiment will be described, but in the following description, the differences from the first embodiment will be mainly described, and the same matters will be omitted. In FIG. 5, the same components as those in the first embodiment are designated by the same reference numerals as those described above.

The sensor optical waveguide 1A shown in FIG. 5 is the same as the sensor optical waveguide 1 shown in FIG. 1, except that the configurations of the branch portion 16 and the coupling portion 17 are different.

In the branch portion 16 shown in FIG. 1 described above, the light propagating through the incident core portion 141 is distributed to four through one branch point. On the other hand, in the branch portion 16 shown in FIG. 5, the light is distributed to four through the three branch points 16a, 16b, and 16b. Specifically, the incident core portion 141 is branched into two at the branch point 16a, and further branched into two at the two branch points 16b and 16b. By having a plurality of branch points in this way, it is possible to reduce the branch loss in the branch portion 16 as compared with the first embodiment. Then, if the branch loss can be reduced, the decrease in the level of the emitted light amount is suppressed, so that the decrease range of the emitted light amount can be detected more accurately.

Further, in the coupling portion 17 shown in FIG. 5, light is mixed into one through three coupling points 17a, 17b, and 17b. Specifically, the first sensing core portion 143 and the second sensing core portion 144 are coupled to one at the coupling point 17b, and similarly, the third sensing core portion 145 and the fourth sensing core portion 146 are coupled to each other at the coupling point 17b. It is combined into one at 17b. Then, the core portions 14, 14 extending from the two coupling points 17b, 17b are coupled to one at the coupling point 17a. By having a plurality of coupling points in this way, it is possible to reduce the coupling loss at the coupling portion 17. Then, if the coupling loss can be reduced, the decrease in the level of the emitted light amount is suppressed, so that the decrease range of the emitted light amount can be detected more accurately.

Also in the second embodiment as described above, the same effect as that of the above-described embodiment can be obtained.

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

Hereinafter, the third embodiment will be described, but in the following description, the differences from the first embodiment will be mainly described, and the same matters will be omitted. In FIG. 6, the same components as those in the first embodiment are designated by the same reference numerals as those described above.

The sensor optical waveguide 1B shown in FIG. 6 is the same as the sensor optical waveguide 1 shown in FIG. 1, except that the configurations of the branch portion 16 and the coupling portion 17 such as the first sensing core portion 143 and the like are different.

In the sensor optical waveguide 1 shown in FIG. 1 described above, the light propagating through the incident core portion 141 is equally distributed to four by the branch portion 16. On the other hand, in the sensor optical waveguide 1B shown in FIG. 6, the distribution ratios in the branch portions 16 are not equal distributions but different from each other. Specifically, the distribution ratio to the first sensing core unit 143 is 10, the distribution ratio to the second sensing core unit 144 is 30, the distribution ratio to the third sensing core unit 145 is 60, and the distribution ratio to the fourth sensing core unit 146. The branch portion 16 is configured so that the value is 120.

Then, in order to realize such a distribution ratio, the branch portion 16 shown in FIG. 6 is connected to the first branch path 1601 connected to the first sensing core portion 143 and the second sensing core portion 144. The widths of the two branch paths 1602, the third branch path 1603 connected to the third sensing core section 145, and the fourth branch path 1604 connected to the fourth sensing core section 146 are set to the above-mentioned distribution ratios. The width is set according to it. Further, the first sensing core section 143 following the first branch path 1601, the second sensing core section 144 following the second branch path 1602, the third sensing core section 145 following the third branch path 1603, and the fourth branch path. Each width of the fourth sensing core portion 146 following the 1604 is set to a width corresponding to the above-mentioned distribution ratio. That is, the ratio of the width of the first sensing core portion 143, the width of the second sensing core portion 144, the width of the third sensing core portion 145, and the width of the fourth sensing core portion 146 is 10:30:60:120. It is set as.

By setting the width in this way, the amount of light propagating through 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 has a difference according to the distribution ratio. Will have. Therefore, for example, when the first sensing core portion 143 is broken as shown in FIG. 4, the amount of light emitted corresponds to 10 / (10 + 30 + 60 + 120) ≈4.5 in the amount of emitted light. The decrease in the amount of emitted light is the decrease in the case where the second sensing core portion 144 is broken, the decrease in the case where the third sensing core portion 145 is broken, and the fourth sensing core portion 146. It is different from any of the reductions when That is, in the sensor optical waveguide 1B shown in FIG. 6, the first sensing core portion 143 and the like each have a unique emission light amount reduction width. Therefore, by detecting the reduction width of the emitted light amount, not only the breakage occurred in the unit core portion 10a, but also the breakage occurred in any of the first sensing core portions 143 and the like included in the unit core portion 10a. It becomes possible to detect whether or not. Therefore, in the present embodiment, it is possible to realize the optical waveguide 1B for a sensor that can specify the position where the abnormality of the adherend 9 occurs with higher position resolution.

As described above, in order to give the first sensing core unit 143 and the like a unique emission light amount reduction range, for example, the distribution ratio may be set so as to satisfy the following three elements.

(A) Distinguish distribution ratios between sensing cores (b) The sum of two or more arbitrarily selected distribution ratios does not match any of the remaining distribution ratios (c) Two or more arbitrarily selected distribution ratios The sum of the distribution ratios does not match the sum of the remaining two or more distribution ratios

On the other hand, in the present embodiment, each width of the first sensing core portion 143 and the like is also set to a width corresponding to the above-mentioned distribution ratio. As a result, it is possible to suppress the transmission loss of the first sensing core unit 143 and the like from affecting the distribution ratio described above. That is, it is possible to prevent the distribution ratio set in the branch portion 16 from shifting due to the transmission loss of the first sensing core portion 143 and the like.

In the present embodiment, the width of the branch path and the sensing core portion described above is set according to the distribution ratio, but the width is set according to the distribution ratio depending on the cross-sectional shape of the branch path and the sensing core portion. The diameter, which is a concept to be included, may be set.

As described above, in the sensor optical waveguide 1B according to the present embodiment, at least the diameters of the first sensing core portion 143 and the second sensing core portion 144 are different from each other. As a result, it is possible to give each sensing core portion a unique emission light amount reduction range. As a result, by detecting the amount of decrease in the amount of emitted light, it becomes possible to detect which sensing core portion has broken or the like. Therefore, by using the optical waveguide 1B for the sensor, it is possible to realize a sensing system capable of specifying the position where the abnormality of the adherend 9 occurs in a region narrower than the unit core portion 10. That is, the optical waveguide 1B for the sensor contributes to the realization of a sensing system having higher position resolution for detecting the abnormality of the adherend 9.

Further, the sensor optical waveguide 1B according to the present embodiment has at least a third sensing core portion 145 in parallel with the first sensing core portion 143 and the second sensing core portion 144. The diameter of the third sensing core portion 145 is larger than the sum of the diameter of the first sensing core portion 143 and the diameter of the second sensing core portion 144.

According to such a configuration, even when there are three sensing core portions, it is possible to give each sensing core portion a unique emission light amount reduction range. As a result, even when there are three sensing core portions, it is possible to detect which sensing core portion has broken or the like. That is, it is possible to realize a sensing system in which the position where the abnormality of the adherend 9 occurs can be specified in a wider range and with higher position resolution.
Also in the third embodiment as described above, the same effect as that of the above-described embodiment can be obtained.

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

FIG. 7 is a plan view showing an optical waveguide for a sensor according to a fourth embodiment. 8 and 9 are plan views for explaining how to use the optical waveguide for a sensor shown in FIG. 7, respectively.

Hereinafter, the fourth embodiment will be described, but in the following description, the differences from the first embodiment will be mainly described, and the same matters will be omitted. In FIG. 7, the same components as those in the first embodiment are designated by the same reference numerals as those described above.

The sensor optical waveguide 1C shown in FIG. 7 is different in the number of unit core portions 10 and the number of distributions in the branch portion 16, and the sensor optical waveguide 1C shown in FIG. 1 is provided with the addition of the first dimming unit 31. It is the same as the waveguide 1.

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

In the branch portion 16 shown in FIG. 7, the light is equally distributed in two. Further, the optical waveguide 1C for a sensor includes a first dimming unit 31 provided in the first sensing core unit 143. Specifically, the first dimming section 31 shown in FIG. 7 has a dimming branch section 311 provided at the end of the first sensing core section 143 and a dimming core section extending from the dimming branch section 311. It has 312 and. The dimming branch portion 311 branches the terminal portion of the first sensing core portion 143 into two, one of which is connected to the coupling portion 17 and the other of which is connected to the dimming core portion 312. The dimming core portion 312 shown in FIG. 7 does not reach the end surface of the core layer 13, and is interrupted in the middle. The dimming core portion 312 may reach the end surface of the core layer 13 as long as it is not connected to the light receiving portion. Further, the coupling portion 17 shown in FIG. 7 has a first coupling core portion 171 that connects the dimming branch portion 311 and the exit core portion 142.

The light propagating through the first sensing core portion 143 is equally distributed in two by the dimming branch portion 311. One of the distributed lights is guided to the first coupling core portion 171 and the other is guided to the dimming core portion 312. The light guided to the first coupling core portion 171 is mixed with the light propagating through the second sensing core portion 144, and is emitted from the exit core portion 142. The light guided to the dimming core portion 312 diffuses at the end. Therefore, the first dimming section 31 has a function of reducing the amount of light distributed to the dimming core section 312.

FIG. 7 shows a case where light is incident on the unit core portion 10a with a light amount of 100. Since the incident light is equally distributed to the two at the branch portion 16, the amount of light 50 is distributed to the first sensing core portion 143 and the second sensing core portion 144. Then, the light distributed to the first sensing core portion 143 is further equally distributed to two by the dimming branch portion 311. Therefore, the light amount of 25 is distributed to the first coupling core portion 171 and the dimming core portion 312. Will be. As a result, the amount of emitted light becomes 75. This amount of light is the amount of emitted light in normal times.

FIG. 8 is a plan view showing an optical waveguide 1C for a sensor attached to an adherend 9 (not shown). When the surface of the adherend 9 is changed, for example, the broken portion 1430 shown in FIG. 8 is generated in the optical waveguide 1 for the sensor. Since the broken portion 1430 is a void, the light propagating through the first sensing core portion 143 is blocked by the broken portion 1430. As a result, the amount of emitted light in the unit core portion 10a is smaller than in normal times. Specifically, since the amount of light 25 is lost, the amount of emitted light is 50. Therefore, it is possible to detect that the amount of light in the unit core portion 10a is smaller than that in the unit core portions 10b, 10c, and 10d. Moreover, since the emission light amount reduction width is 25, it is possible to detect that the broken portion 1430 has occurred in the first sensing core portion 143 instead of the second sensing core portion 144. This is because if the broken portion 1430 is generated in the second sensing core portion 144, the amount of emitted light is 25, and the amount of decrease in the amount of emitted light is 50. Therefore, by using the optical waveguide 1C for the sensor, it is possible to detect that some mechanical or thermal change has occurred in the position of the adherend 9 corresponding to the first sensing core portion 143.

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

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

According to such a configuration, even if the distribution ratio in the branch portion 16 is equal distribution, the amount of emitted light is reduced when the break portion 1430 occurs in the first sensing core portion 143 and the second sensing core portion 144. The width can be different. Therefore, it is possible to specify in which of the first sensing core portion 143 and the second sensing core portion 144 the fractured portion 1430 has occurred, based on the amount of emitted light.

Further, since strictly controlling the distribution ratio of the branch portion 16 may have a high manufacturing difficulty, if the distribution ratio of the branch portion 16 may be equal distribution, the manufacturing difficulty can be lowered.

Therefore, such an optical waveguide 1C for a sensor can be easily manufactured, and can realize a sensing system capable of specifying the position, size, and the like where an abnormality occurs in the adherend 9.
Also in the fourth embodiment as described above, the same effect as that of the above-described embodiment can be obtained.

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

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

Hereinafter, the fifth embodiment will be described, but in the following description, the differences from the second embodiment will be mainly described, and the same matters will be omitted. In addition, in FIGS. 10 and 11, the same reference numerals as those described above are attached to the same configurations as those of the second embodiment.

The sensor optical waveguide 1D shown in FIGS. 10 and 11 has a first dimming section 31, a second dimming section 32, and a third dimming section 33.

As described above, the first dimming section 31 includes a dimming branch section 311 provided at the terminal portion of the first sensing core section 143 and a dimming core section 312 extending from the dimming branch section 311. Have. The dimming branch portion 311 branches the first sensing core portion 143 into two, one of which is connected to the coupling portion 17 and the other of which is connected to the dimming core portion 312. The dimming core portion 312 shown in FIGS. 10 and 11 is not connected to the light receiving portion. The dimming core portion 312 may reach the end surface of the core layer 13 as long as it is not connected to the light receiving portion.

As shown in FIGS. 10 and 11, the second dimming section 32 includes a dimming branch section 321 provided at the end of the second sensing core section 144 and a dimming core extending from the dimming branch section 321. It has a unit 322 and. The dimming branch portion 321 branches the second sensing core portion 144 into two, one of which is connected to the coupling portion 17 and the other of which is connected to the dimming core portion 322. The dimming core portion 322 shown in FIGS. 10 and 11 is not connected to the light receiving portion. The dimming core portion 322 may reach the end surface of the core layer 13 as long as it is not connected to the light receiving portion.

As shown in FIGS. 10 and 11, the third dimming section 33 includes a dimming branch section 331 provided at the end of the third sensing core section 145 and a dimming core extending from the dimming branch section 331. It has a unit 332 and. The dimming branch portion 331 branches the third sensing core portion 145 into two, one of which is connected to the coupling portion 17 and the other of which is connected to the dimming core portion 332. The dimming core portion 332 shown in FIGS. 10 and 11 is not connected to the light receiving portion. The dimming core portion 332 may reach the end surface of the core layer 13 as long as it is not connected to the light receiving portion.

Further, the coupling portion 17 shown in FIGS. 10 and 11 includes a first coupling core portion 171, a second coupling core portion 172, and a third coupling core portion 173.

The first coupling core unit 171 couples the first sensing core unit 143 and the second sensing core unit 144 via the first dimming unit 31. The second coupling core portion 172 connects the second sensing core portion 144 and the third sensing core portion 145 via the second dimming portion 32. The third coupling core portion 173 connects the third sensing core portion 145 and the fourth sensing core portion 146 via the third dimming unit 33. In this way, the coupling portion 17 connects the first sensing core portion 143 and the like to the exit core portion 142.

FIG. 11 shows a case where light is incident on the unit core portion 10 with a light amount of 100.

Since the incident light is equally distributed to the four by the branch portion 16, the light amount of 25 is distributed to the first sensing core unit 143 and the like. Since the light distributed to the first sensing core portion 143 is equally distributed in two by the dimming branch portion 311, the light amount of 12.5 is distributed to the first coupling core portion 171 and the dimming core portion 312. It will be.

The light distributed to the first coupling core unit 171 is mixed with the light distributed to the second sensing core unit 144. Therefore, in the second sensing core portion 144, the amount of light is 25 + 12.5 = 37.5 between the first coupling core portion 171 and the second coupling core portion 172. Since this amount of light is further equally distributed to the two by the dimming branch portion 321, the amount of light is 18.75 each distributed to the second coupling core portion 172 and the dimming core portion 322.

The light distributed to the second coupling core unit 172 is mixed with the light distributed to the third sensing core unit 145. Therefore, in the third sensing core portion 145, the amount of light is 25 + 18.75 = 43.75 between the second coupling core portion 172 and the third coupling core portion 173. Since this amount of light is further equally distributed in two by the dimming branch portion 331, the amount of light is 21.875 each distributed to the third coupling core portion 173 and the dimming core portion 332.

The light distributed to the third coupling core portion 173 is mixed with the light distributed to the fourth sensing core portion 146 and guided to the exit core portion 142. Therefore, the amount of emitted light is 25 + 21.875 = 46.875. This amount of light is the amount of emitted light in normal times.

In such an optical waveguide 1D for a sensor, light passes between 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 until light is emitted. The number of dimming parts is different from each other. Therefore, when a break occurs in each sensing core portion, the amount of decrease in the amount of emitted light differs between the sensing core portions. That is, an eigenvalue of the emission light amount reduction width is given. For example, when the first sensing core portion 143 of FIG. 11 is broken, the emission light amount reduction width is 3.125. Similarly, the reduction width of the emitted light amount when the second sensing core portion 144 is broken is 6.25, the reduction width of the emitted light amount when the third sensing core portion 145 is broken is 12.5, and the fourth sensing. When the core portion 146 is broken, the emission light amount reduction width is 25. Therefore, by detecting the amount of decrease in the amount of emitted light, it is possible to detect the position, size, and the like where the abnormality of the adherend 9 is occurring.

As described above, the sensor optical waveguide 1D according to the present embodiment includes 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 that are parallel to each other. Have. Further, the optical waveguide 1D for a sensor has a first dimming section 31, a second dimming section 32, and a third dimming section 33. The first dimming unit 31 is provided in the first sensing core unit 143, and reduces the amount of light propagating through the first sensing core unit 143. The second dimming unit 32 is provided in the second sensing core unit 144, and reduces the amount of light propagating through the second sensing core unit 144. The third dimming unit 33 is provided in the third sensing core unit 145 and reduces the amount of light propagating through the third sensing core unit 145. The coupling portion 17 included in the optical waveguide 1D for the sensor has the amount of light after dimming by the first dimming section 31, the amount of light after dimming by the second dimming section 32, and the dimming by the third dimming section 33. The amount of light after light and the amount of light propagating through the fourth sensing core portion 146 are combined and configured to be coupled to the exit core portion 142.

According to such a configuration, even when there are four sensing core portions, when a break occurs in each sensing core portion, the emission light amount reduction width can be made different between the sensing core portions. Therefore, by detecting the amount of decrease in the amount of emitted light, it is possible to identify the sensing core portion where the fracture has occurred. Therefore, by using the optical waveguide 1D for the sensor, it is possible to realize a sensing system capable of specifying the position, size, etc. where the abnormality of the adherend 9 is occurring.
Also in the fifth embodiment as described above, the same effect as that of the above-described embodiment can be obtained.

6. Sixth Embodiment Next, the optical waveguide for a sensor according to the 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 how to use the optical waveguide for a sensor shown in FIG.

Hereinafter, the sixth embodiment will be described, but in the following description, the differences from the fourth embodiment will be mainly described, and the same matters will be omitted. In addition, in FIG. 12 and FIG. 13, the same reference numerals as those described above are attached to the same configurations as those of the fourth embodiment.

The sensor optical waveguide 1E shown in FIG. 12 is the same as the sensor optical waveguide 1C shown in FIG. 7, except that the number of unit core units 10 is different and the light amount adjusting units 4B and 4C are added.

The sensor optical waveguide 1E shown in FIG. 12 has four unit core portions 10 of a first unit core portion 10A, a second unit core portion 10B, a third unit core portion 10C, and a fourth unit core portion 10D. .. The first unit core portion 10A, the second unit core portion 10B, the third unit core portion 10C, and the fourth unit core portion 10D are arranged in large numbers along the X axis of FIG. It is an excerpt from a part of the column. Hereinafter, the second unit core portion 10B and the third unit core portion 10C will be described as representatives, and the description of the first unit core portion 10A and the fourth unit core portion 10D having the same configuration will be omitted.

The second unit core portion 10B includes a light amount adjusting portion 4B provided in the first sensing core portion 143, and a coupling portion 17B as the coupling portion 17 described above. Specifically, the light quantity adjusting unit 4B shown in FIG. 12 extends from the light quantity adjusting branch portion 41B provided at the terminal portion of the first sensing core portion 143 of the second unit core portion 10B and the light quantity adjusting branch portion 41B. It has a light amount adjusting core portion 42B and a light amount adjusting core portion 42B. The light amount adjusting branch portion 41B branches the first sensing core portion 143 of the second unit core portion 10B into two. Then, one of the light quantity adjusting core portions 42B after branching is coupled to the second sensing core portion 144 of the first unit core portion 10A. Further, the coupling portion 17B has a coupling core portion 171B, and the coupling core portion 171B couples the other after branching to the second sensing core portion 144 of the second unit core portion 10B.

The third unit core portion 10C includes a light amount adjusting portion 4C provided in the first sensing core portion 143, and a coupling portion 17C as the coupling portion 17 described above. Specifically, the light quantity adjusting unit 4C shown in FIG. 12 extends from the light quantity adjusting branch portion 41C provided at the terminal portion of the first sensing core portion 143 of the third unit core portion 10C and the light quantity adjusting branch portion 41C. It has a light amount adjusting core portion 42C and a light amount adjusting core portion 42C. The light amount adjusting branch portion 41C branches the first sensing core portion 143 of the third unit core portion 10C into two. Then, one of the light quantity adjusting core portions 42C after branching is coupled to the second sensing core portion 144 of the second unit core portion 10B. Further, the coupling portion 17C has a coupling core portion 171C, and the coupling core portion 171C couples the other after branching to the second sensing core portion 144 of the third unit core portion 10C.

FIG. 12 shows a case where light is incident on the first unit core portion 10A, the second unit core portion 10B, the third unit core portion 10C, and the fourth unit core portion 10D with a light amount of 100, respectively. Since the incident light is equally distributed to the two at the branch portion 16, the amount of light 50 is distributed to each of the first sensing core unit 143 and each second sensing core unit 144.

For example, in the second unit core portion 10B, the light quantity 50 is further equally distributed in two by the light quantity adjusting branch portion 41B, so that the light quantity 25 is distributed to the coupled core portion 171B and the light quantity adjusting core portion 42B. ..

Further, in the third unit core portion 10C, since the light quantity 50 is further equally distributed in two by the light quantity adjusting branch portion 41C, the light quantity 25 is distributed to the coupled core portion 171C and the light quantity adjusting core portion 42C. ..

Then, the coupling core portion 171B and the light amount adjusting core portion 42C join the second sensing core portion 144 of the second unit core portion 10B, and then are connected to the emission core portion 142. That is, the amount of light is added to the second unit core portion 10B from the adjacent third unit core portion 10C. Including this additional amount, the amount of emitted light of the second unit core portion 10B becomes 100. Then, this amount of light becomes the amount of emitted light in the second unit core portion 10B in normal times. Similarly, in the first unit core portion 10A, the third unit core portion 10C, and the fourth unit core portion 10D, the amount of light is added from the adjacent unit core portions, and the amount of emitted light in normal times is 100, respectively.

FIG. 13 is a plan view showing an optical waveguide 1E for a sensor attached to an adherend 9 (not shown). When an abnormality or the like occurs on the surface of the adherend 9, for example, a broken portion 1432 shown in FIG. 13 is generated in the optical waveguide 1E for a sensor. Since the broken portion 1432 is a void, 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 generated. Each is blocked by the broken portion 1432. As a result, each light quantity 50 is lost.

On the other hand, in normal times, as described above, the light intensity 25 is transmitted from the first sensing core section 143 of the third unit core section 10C to the second sensing core section 144 of the second unit core section 10B via the light intensity adjusting section 4C. It is supposed to be added. However, in FIG. 13, since the broken portion 1432 rests on the first sensing core portion 143 of the third unit core portion 10C, the light amount 25 is not added. As a result, the amount of emitted light of the second unit core portion 10B is 25 by subtracting 75 (= 50 + 25) from the original 100.

Further, since the light amount of the first sensing core part 143 of the third unit core part 10C becomes 0, the light amount of the coupled core part 171C also decreases from 25 in normal times to 0. As a result, the amount of emitted light of the third unit core portion 10C is 75 by subtracting 25 from the original 100.

Based on the above, in the optical waveguide 1E for a sensor shown in FIG. 13, in each unit core portion 10, the first sensing core portion 143 is broken and the second sensing core portion 144 is broken. The amount of light reduction is different. Therefore, based on the amount of decrease in the amount of emitted light of each unit core portion 10, it is specified which of the first sensing core portion 143 and the second sensing core portion 144 has the broken portion 1432 in each unit core portion 10. It will be possible to do.

Further, in particular, when a broken portion 1432 occurs on the first sensing core portion 143 side of each unit core portion 10, a decrease in the amount of emitted light is detected in both of the two adjacent unit core portions 10. Can be done. Therefore, for example, even if some abnormality occurs in the light receiving portion that detects the emitted light amount of one unit core portion 10, the occurrence of the broken portion 1432 is detected by detecting the emitted light amount of the other unit core portion 10. be able to. As a result, although the position resolution is slightly lowered, the robustness is improved, so that the reliability of the sensing system can be improved.

Further, when the broken portion 1432 occurs so as to straddle the adjacent unit core portions 10, the amount of decrease in the amount of emitted light becomes larger than that of other embodiments. Therefore, it is possible to realize a sensing system capable of more reliably detecting a change in the amount of emitted light.

As described above, the sensor optical waveguide 1E according to the present embodiment has at least the first unit core portion 10A, the second unit core portion 10B, and the third unit core portion 10C as the unit core portion 10. .. The first unit core portion 10A, the second unit core portion 10B, and the third unit core portion 10C are arranged in this order. Further, the second unit core portion 10B branches the first sensing core portion 143 of the second unit core portion 10B, and one of the branches is coupled to the second sensing core portion 144 of the first unit core portion 10A. The other after branching is coupled to the second sensing core portion 144 of the second unit core portion 10B (light intensity adjusting portion 4B and coupling portion 17B). Further, the third unit core portion 10C branches the first sensing core portion 143 of the third unit core portion 10C, and one of the branches is coupled to the second sensing core portion 144 of the second unit core portion 10B. The other after branching is coupled to the second sensing core portion 144 of the third unit core portion 10C (light intensity adjusting portion 4C and coupling portion 17C).

According to such a configuration, the broken portion 1432 is provided in any of the first sensing core portion 143 and the second sensing core portion 144 in each unit core portion 10 based on the emission light amount reduction width of each unit core portion 10. It becomes possible to identify whether it has occurred. In particular, when the broken portion 1432 occurs so as to straddle the adjacent unit core portions 10, the amount of decrease in the amount of emitted light is larger than that of the other embodiments, so that the optical waveguide 1E for the sensor is highly reliable. Contribute to the realization of a sensing system.
Also in the sixth embodiment as described above, the same effect as that of the above-described embodiment can be obtained.

Although the optical waveguide for a sensor of the present invention has been described above based on the illustrated embodiment, the present invention is not limited thereto.

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

1 Optical waveguide for sensor 1A Optical waveguide for sensor 1B Optical waveguide for sensor 1C Optical waveguide for sensor 1E Optical waveguide for sensor 2 Adhesive layer 4B Light intensity adjustment unit 4C Light intensity adjustment unit 9 Adhesion 10 Unit core unit 10A 1st unit core part 10B 2nd unit core part 10C 3rd unit core part 10D 4th unit core part 10a Unit core part 10b Unit core part 10c Unit core part 10d Unit core part 11 Clad layer 12 Clad layer 13 Core layer 14 core Part 15 Side clad part 16 Branch part 16a Branch point 16b Branch point 17 Bonding part 17B Bonding part 17C Bonding part 17a Bonding point 17b Bonding point 18 First cover layer 19 Second cover layer 31 First dimming part 32 Second dimming Part 33 3rd dimming part 41B Light amount adjustment branch part 41C Light amount adjustment branch part 42B Light amount adjustment core part 42C Light amount adjustment core part 101 Adhesive surface 141 Incident core part 142 Emitting core part 143 1st sensing core part 144 2nd sensing core part 145 3rd sensing core part 146 4th sensing core part 171 1st coupling core part 171B Bonded core part 171C Bonded core part 172 2nd coupling core part 173 3rd coupling core part 311 Dimming branch part 312 Dimming core part 321 Decreased Optical branch 322 Dimming core 331 Dimming core 332 Dimming core 1410 Incident surface 1420 Exit surface 1430 Breaking part 1431 Breaking part 1432 Breaking part 1601 First branch road 1602 Second branch road 1603 Third branch road 1604 4 branch roads

Claims (6)

An optical waveguide for a sensor that is attached to an adherend and is used in a sensing system that detects mechanical or thermal changes in the adherend.
Incident core part and
Ejecting core part and
The first sensing core part and the second sensing core part that are parallel to each other,
A branch portion that branches the incident core portion and connects to 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 and connects to the exit core portion.
An optical waveguide for a sensor, characterized by having at least one unit core portion comprising. The optical waveguide for a sensor according to claim 1, wherein the first sensing core portion and the second sensing core portion have different diameters from each other. It has a first sensing core unit and a third sensing core unit parallel to the second sensing core unit.
The optical waveguide for a sensor according to claim 2, wherein the diameter of the third sensing core portion is larger than the sum of the diameter of the first sensing core portion and the diameter of the second sensing core portion. The optical waveguide for a sensor according to claim 1, which is provided in the first sensing core portion and has a first dimming portion that reduces the amount of light propagating through the first sensing core portion. The third sensing core part and the fourth sensing core part parallel to the second sensing core part,
A second dimming section provided in the second sensing core section and reducing the amount of light propagating through the second sensing core section.
A third dimming section provided in the third sensing core section and reducing the amount of light propagating through the third sensing core section.
Have,
The coupling portion includes 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 fourth. The optical waveguide for a sensor according to claim 4, wherein the amount of light propagating in the sensing core portion is combined with the light amount of the light propagating in the sensing core portion and coupled to the emission core portion. The unit core unit includes a first unit core unit, a second unit core unit, and a third unit core unit.
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 branches the first sensing core portion of the second unit core portion, and one after branching is coupled to the second sensing core portion of the first unit core portion, and after branching. Has a structure in which the other of the above is coupled to the second sensing core portion of the second unit core portion.
The third unit core portion branches the first sensing core portion of the third unit core portion, and one of the branches is coupled to the second sensing core portion of the second unit core portion, and after branching. The optical waveguide for a sensor according to any one of claims 1 to 3, which has a structure in which the other of the above is coupled to the second sensing core portion of the third unit core portion.

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