WO2024100862A1

WO2024100862A1 - Optical transmission system

Info

Publication number: WO2024100862A1
Application number: PCT/JP2022/042008
Authority: WO
Inventors: 誉人桐原; 聖成川; 勝久田口; 亜弥子岩城; 和秀中島; 隆松井; 千里深井; 悠途寒河江
Original assignee: 日本電信電話株式会社
Priority date: 2022-11-10
Filing date: 2022-11-10
Publication date: 2024-05-16

Abstract

The purpose of the present invention is to provide an optical transmission system that is able to couple power of light requested by respective regions to be irradiated to a single core optical fiber of bundled optical fibers corresponding to each of the regions to be irradiated.　An optical transmission system according to the present invention is characterized by comprising: a light source part 11 that outputs light L1; an optical transmission path that propagates the light L1 through a plurality of cores of a bundled optical fiber 36 in which a plurality of single core optical fibers 51a are bundled; and an optical coupling part 11d that causes the light L1 outputted by the light source part 11 to be incident to the plurality of cores, wherein the optical coupling part 11d arbitrarily adjusts the coupling states of the light L1 incident to the cores, and, as the adjustment of the coupling states, adjusts the spot shape of the light L1 between a size in which all of the cores are included and a size in which only one of the plurality of cores is included.

Description

Optical Transmission System

This disclosure relates to an optical transmission system that uses an optical bundle made of multiple optical fibers as an optical transmission path.

There is an increasing demand for systems that use ultraviolet light to sterilize and inactivate viruses for the purpose of preventing infectious diseases. There are three main categories of such systems. In this specification, the term "sterilization, etc." refers to sterilization and inactivation of viruses.
(I) Mobile sterilization robot The product of Non-Patent Document 1 is an autonomous mobile robot that irradiates ultraviolet light. The robot can irradiate ultraviolet light while moving around a room in a building such as a hospital room, thereby automatically sterilizing a wide area without human intervention.
(II) Freestanding Air Purifier The product in Non-Patent Document 2 is a device that is installed on the ceiling or a predetermined location in a room and circulates the air in the room while sterilizing, etc. This device does not directly irradiate ultraviolet light and has no effect on the human body, so it is possible to sterilize, etc. with a high degree of safety.
(III) Portable sterilization device The product of Non-Patent Document 3 is a portable device equipped with an ultraviolet light source. A user can take the device to a desired area and irradiate ultraviolet light. Therefore, the device can be used in various places.

However, the devices described in the non-patent literature have the following problems.
(1) Economic Efficiency The product of Non-Patent Document 1 irradiates high-power ultraviolet light, so the device is large-scale and expensive. Therefore, the product of Non-Patent Document 1 has a problem that it is difficult to realize an economical system.
(2) Versatility With the product of Non-Patent Document 1, the areas to be irradiated with ultraviolet light are limited to areas where a robot can move/enter, making it difficult to irradiate narrow or deep areas with ultraviolet light.
The product of Non-Patent Document 2 sterilizes the circulated indoor air, and therefore cannot irradiate the location where sterilization is desired with ultraviolet light directly.
The product of Non-Patent Document 3 cannot irradiate ultraviolet light onto, for example, narrow pipes or areas where people cannot enter.
As described above, the products described in non-patent documents have a problem in that they lack versatility in terms of being able to irradiate ultraviolet light at any location.
(3) Operability The product of Non-Patent Document 3 is portable and can irradiate ultraviolet light in various locations. However, in order to obtain sufficient sterilization effects at the target location, the user is required to have skills and knowledge, and there are problems with operability.

To address these issues, an ultraviolet light irradiation system 300 using optical fibers as shown in FIG. 1 can be considered. In this ultraviolet light irradiation system, ultraviolet light is transmitted from the ultraviolet light source unit 11a using a thin and easily bendable optical fiber, and the ultraviolet light output from the tip of the optical fiber 14 is irradiated to the irradiation target area AR where pinpoint sterilization is desired. Since ultraviolet light can be irradiated to any location simply by moving the irradiation unit 13 at the tip of the optical fiber 14, the versatility of the above issue (2) can be resolved. In addition, since there is no need to move or set up the ultraviolet light source, and no skill or knowledge is required of the user, the operability of the above issue (3) can also be resolved. Furthermore, by providing an optical distribution unit 12 such as an optical splitter in the optical transmission path 16 and configuring a system of P-MP (Point to Multipoint) such as FTTH (Fiber To The Home), multiple locations can be sterilized by sharing a single light source. Therefore, the economics of the above issue (1) can also be resolved.

Furthermore, in an ultraviolet light irradiation system, it has been proposed to use an inexpensive LED (Light-Emitting Diode) as a light source instead of a laser, which has a high coupling efficiency to an optical fiber, to reduce system costs. Here, "coupling efficiency" means the ratio of the power input to the optical fiber (optically coupled to the optical fiber core) to the output power of the light source.
The problem with this proposal is shown in Figure 2. Since the light-emitting surface of an LED is larger than that of a laser, even if you try to couple the light output from the LED to a single-core optical fiber, the core area in the cross section is narrow, and most of the light is not coupled, resulting in low coupling efficiency (Figure 2(A)). This is the same even if you narrow the light output from the LED using an optical system such as a lens (Figure 2(B)). In other words, when an LED is used as a light source, there is a problem that most of the output power of the light source cannot be effectively used.
This problem is not limited to optical transmission systems that transmit ultraviolet light, but is a common problem to optical transmission systems that transmit infrared light or visible light.

Here, if light is coupled to multiple cores present in the cross section, such as in a multi-core optical fiber (MCF) or a bundled optical fiber consisting of multiple single-core optical fibers, the coupling efficiency can be improved and the waste of output power from the light source can be reduced (Figure 2 (C)).

Although the optical fiber bundle can reduce waste of the output power of the light source in this way, it also has problems as shown in FIG.
3A is a diagram for explaining how the light L1 from the light source unit 11 is irradiated onto one end of the bundle optical fiber 36, how the bundle optical fiber 36 is separated into each single optical fiber 51a at the other end to become the path 14, and how the light propagating through it is emitted (the irradiation target area ARn is located at the end of the emitted light). The bundle optical fiber 36 is a bundle of multiple single-core optical fibers 51a. The light L1 from the light source unit 11 is irradiated onto one end (the coupling portion) of the bundle optical fiber 36, but the illuminance is not uniform on the irradiation surface (light spot) (there is a power deviation). Specifically, the illuminance is high near the center of the light spot, and low around the light spot.
3A, when the size of one end of the bundle optical fiber 36 is larger than the size Lc of the light spot, the light spot may only partially hit the core of the outer peripheral optical fiber 51a of the bundle optical fiber 36. When light L1 is coupled to the bundle optical fiber 36 in this state, light with a smaller power propagates through the outer peripheral optical fiber 51a of the bundle optical fiber 36 than through the central optical fiber 51a.
In this state, when each optical fiber 51a is separated into its respective irradiation target area at the other end (separation portion) of the bundle optical fiber 36, the light emitted from the optical fiber 51a on the outside of the bundle optical fiber 36 will have lower power than the light emitted from the optical fiber 51a near the center of the bundle optical fiber 36.
This problem also occurs when the light L1 is narrowed down by the optical system 11c (FIG. 3B).

Furthermore, to prevent the above-mentioned power deviation from occurring, it is necessary to make the area of the light spot at the coupling portion larger than the area of one end of the bundle optical fiber 36 (FIG. 3(C)). However, doing so will result in some light not being able to be coupled to the bundle optical fiber 36, resulting in large power losses and wasting the power of the light source unit 11. This means that it is difficult to shorten the time that irradiation is possible due to the amount of wasted power, and it is difficult to reduce the power consumption for the operating time of the irradiating light source, which results in difficulty in reducing costs.

In other words, in a Point-to-Multipoint configuration ultraviolet light irradiation system that utilizes the characteristics of bundling to separate and transmit signals to a single-core optical fiber,
(Problem 1) Since power deviation occurs at the coupling portion from the light source to the bundle optical fiber, it is difficult to transmit and receive power fairly to each irradiation portion, and (Problem 2) if one tries to eliminate the power deviation, it is difficult to reduce costs and power consumption.
There is a problem that...

However, each irradiation target area ARn of the ultraviolet light irradiation system 300 in FIG. 1 does not necessarily require ultraviolet light of the same power. For example, the irradiation target area AR1 may require ultraviolet light of twice the power of the irradiation target area ARN, while the irradiation target area AR2 may be sufficient with ultraviolet light of 1/2 the power of the irradiation target area ARN. In this way, when each irradiation target area ARn requires ultraviolet light of different power, coupling light to each single-core optical fiber of the bundle optical fiber so that the power is uniform is not fair to the requirements.

In view of the above-mentioned circumstances, the present invention aims to provide an optical transmission system that can couple the optical power required by each irradiation target area to a single-core optical fiber of a bundle optical fiber corresponding to each irradiation target area.

In order to achieve the above objective, the optical transmission system of the present invention actively utilizes the power deviation of the light from the light source unit to couple light to one end of the bundle optical fiber.

Specifically, the optical transmission system according to the present invention comprises:
A light source unit that outputs light;
an optical transmission line that propagates the light through a plurality of cores of an optical bundle formed by bundling a plurality of single-core optical fibers;
an optical coupling unit that causes the light output from the light source unit to enter the multiple cores;
An optical transmission system comprising:
The optical coupling unit includes:
The present invention is characterized in that a coupling state in which the light is incident on the cores is arbitrarily adjusted, and as the adjustment of the coupling state, a spot shape of the light is adjusted between a size that includes all of the multiple cores and a size that includes only one of the multiple cores.

By changing the size of the light spot shape, it is also possible to uniformly couple light to all single-core optical fibers included in the bundle optical fiber, and to couple light to one specific fiber or to i specific fibers (i is a natural number less than or equal to I, and I is the number of all single-core optical fibers included in the bundle optical fiber).

Therefore, the present invention can provide an optical transmission system that can couple the optical power required by each irradiation target area to a single-core optical fiber of a bundle optical fiber corresponding to each irradiation target area.

For example, the optical coupling unit is characterized in that it adjusts the coupling state while aligning the optical axis of the light with the central axis of the bundle optical fiber. By narrowing the size of the spot shape, the light is coupled to a single-core optical fiber near the center of the bundle optical fiber, so that a large amount of optical power can be supplied to the irradiation target area corresponding to the single-core optical fiber.

In addition, the single-core optical fiber corresponding to the irradiation target area requiring a large amount of optical power is not necessarily located at the center of the bundle optical fiber. Therefore, the optical coupling unit is characterized in that the optical axis of the light is shifted from the central axis of the bundle optical fiber to adjust the coupling state. By shifting the optical axis, it is possible to irradiate light with a narrowed spot shape at the position where the single-core optical fiber corresponding to the irradiation target area requiring a large amount of optical power is located.

The above inventions can be combined as much as possible.

The present invention can provide an optical transmission system that can couple the optical power required by each irradiation target area to a single-core optical fiber of a bundle optical fiber corresponding to each irradiation target area.

FIG. 1 is a diagram illustrating a problem to be solved by the present invention. FIG. 1 is a diagram illustrating a problem to be solved by the present invention. FIG. 1 is a diagram illustrating a problem to be solved by the present invention. 1 is a diagram illustrating an optical transmission system according to the present invention; 5A and 5B are diagrams for explaining adjustment of a coupling state performed by an optical coupling unit of the optical transmission system according to the present invention; 1 is a diagram illustrating an optical transmission system according to the present invention; 1 is a diagram illustrating an optical transmission system according to the present invention; 1 is a diagram illustrating an optical transmission system according to the present invention; 1 is a diagram illustrating an optical transmission system according to the present invention;

The following describes an embodiment of the present invention with reference to the attached drawings. The embodiment described below is an example of the present invention, and the present invention is not limited to the following embodiment. Note that components with the same reference numerals in this specification and drawings are mutually identical.

(Embodiment 1)
FIG. 4 is a diagram illustrating an optical transmission system 301 according to the present embodiment. The optical transmission system 301 includes:
A light source unit 11 that outputs light L1;
an optical transmission line that propagates light L1 through a plurality of cores of a bundle optical fiber 36 in which a plurality of single-core optical fibers 51a are bundled;
an optical coupling unit 11d that couples the light L1 output from the light source unit 11 to the multiple cores;
Equipped with.

The optical coupling unit 11d is
The coupling state of the light L1 incident on the cores is arbitrarily adjusted, and as the adjustment of the coupling state, a spot shape Lc of the light L1 is adjusted between a size that includes all of the multiple cores and a size that includes only one of the multiple cores.

The light source unit 11 is an LED that outputs ultraviolet light, visible light, or infrared light L1.
3A, the bundle optical fiber 36 is a bundle of a plurality of single-core optical fibers 51a. The single-core optical fibers 51a are separated at the other end T2 and wired to the respective irradiation target areas.

The optical coupling unit 11d adjusts the size of the spot shape of the light L1 from the light source unit 11 and irradiates it onto one end T1 of the bundle optical fiber 36. The size of the spot shape of the light L1 at one end T1 of the bundle optical fiber 36 is indicated by "Lc". The optical coupling unit 11d adjusts the size Lc of the spot shape to adjust the coupling rate of the light coupled to the core of each single-core optical fiber 51a. Here, in this specification, "coupling rate" means the ratio between the total power of the light L1 output by the light source unit 11 and the power of the light L1 coupled to each single-core optical fiber 51a at one end T1 of the bundle optical fiber 36.

By adjusting the coupling rate, the optical coupling unit 11d eliminates the power deviation of the light L1 at one end T1 and couples the light L1 fairly to the core of each single-core optical fiber 51a (realizing power fairness), couples the light L1 to the core of each single-core optical fiber 51a by utilizing the power deviation of the light L1 at one end T1 so as to satisfy the power required by the irradiation target area (realizing fairness of requirements), or reduces the light L1 that is not coupled to the core of the single-core optical fiber 51a (reducing waste and saving power).

Figure 5 is a diagram explaining the adjustment of the coupling state performed by the optical coupling unit 11d. All of Figure 5 shows the state of the size Lc of the spot shape of the light L1 at one end T1 of the bundle optical fiber 36.

Figures 5(A) to 5(C) are diagrams explaining how the optical coupling unit 11d adjusts the coupling state (adjusts the size Lc of the spot shape) while aligning the optical axis of the light L1 with the central axis of the bundle optical fiber 36.

For example, if the optical coupling unit 11d widens the size Lc of the spot shape as shown in FIG. 5(A), uniform power can be coupled to each single-core optical fiber 51a, except for the single-core optical fiber 51a on the outer periphery of the bundle optical fiber 36. In other words, if the optical coupling unit 11d adjusts the size Lc of the spot shape as shown in FIG. 5(A), the uniformity and fairness of the power of the light irradiated to the irradiation target area can be improved. In addition, although there is waste in the power of the light L1 output by the light source unit 11, by widening the size Lc of the spot shape beyond the diameter of the bundle optical fiber 36, uniform power can be coupled even to the single-core optical fiber 51a on the outer periphery.

For example, if the optical coupling unit 11d narrows the size Lc of the spot shape to an extent that only one single-core optical fiber 51a is included, as shown in FIG. 5(B), the light L1 output by the light source unit 11 can be concentrated on the core of the single-core optical fiber 51a, and strong power light can be supplied to the irradiation target area corresponding to the single-core optical fiber 51a. For example, if the light L1 is ultraviolet light, the inactivation of the irradiation target area can be completed in a short period of time.

In addition, to obtain a compromise between the effects described in Figures 5(A) and (B), the optical coupling section 11d can narrow the size Lc of the spot shape to an extent that includes multiple single-core optical fibers 51a located near the center of the bundle optical fiber 36, as shown in Figure 5(C).

The optical coupling unit 11d can change the size Lc of the spot shape according to the requirements of the irradiation target area. The optical coupling unit 11d can know the requirements of the irradiation target area by some means (for example, a light request signal from the irradiation target area, an instruction signal from an operator, etc.).
Furthermore, the optical coupling portion 11d may periodically change the positional relationship as shown in FIG. 5(A) to (B), (B) to (C), and (C) to (A).

Figures 5 (D1) to 5 (D3) are diagrams that explain how the optical coupling unit 11d adjusts the coupling state (adjusts the positional relationship) while shifting the optical axis of the light L1 from the central axis of the bundle optical fiber 36.

The optical coupling unit 11d narrows the size Lc of the spot shape of the light L1 to the extent that only one single-core optical fiber 51a or a plurality of single-core optical fibers 51a are included. Then, the optical coupling unit 11d adjusts the positional relationship between the optical axis of the light L1 and the central axis of the bundle optical fiber 36 so that the single-core optical fiber 51a corresponding to the irradiation target area requesting light is included within the size Lc of the spot shape. If the irradiation target area requesting light changes, the optical coupling unit 11d changes the positional relationship from FIG. 5 (D1) to FIG. 5 (D2) or from FIG. 5 (D1) to FIG. 5 (D3) accordingly. The optical coupling unit 11d can know that the irradiation target area requesting light has changed by some means (for example, a light request signal from the irradiation target area or an instruction signal from the operator).
Furthermore, the optical coupling section 11d may rotate the spot of the light L1 clockwise, such as from (D1) to (D2), from (D2) to (D3), and from (D3) to (D1) in FIG.

The optical coupling section 11d having the above-mentioned function may be mechanically controlled or optically controlled.
For example, in the case where the optical coupling unit 11d is mechanically controlled, when adjusting the size Lc of the spot shape as shown in Figures 5(A) to 5(C), the optical coupling unit 11d adjusts the distance between the light source unit 11 and one end T1 of the bundle optical fiber 36. Also, when adjusting the coupling position of the light as shown in Figures 5(D1) to 5(D3), the optical coupling unit 11d adjusts the positional relationship between the optical axis of the light L1 and the central axis of the bundle optical fiber 36.

On the other hand, if the optical coupling unit 11d is an optical control unit, when adjusting the size Lc of the spot shape as shown in Figures 5 (A) to (C), the focal position of the lens provided is adjusted. Also, when adjusting the light coupling position as shown in Figures 5 (D1) to (D3), the optical coupling unit 11d adjusts the optical components provided (condenser lens, wide-angle lens, beam splitter, prism, mirror, etc.).

(Embodiment 2)
6 is a diagram for explaining an optical transmission system 302 of this embodiment. The optical transmission system 302 is configured to further include a monitoring unit 40 in the irradiation target area AR compared to the optical transmission system 301 of FIG. 4, and to feed back the monitoring value of the light L2 monitored by the monitoring unit 40 to the optical coupling unit 11d. In particular, the optical transmission system 302 is configured to transmit the light L1 from the light source unit 11 as a whole through the bundle optical fiber 36, and irradiate it as light L2 from the other end T2 to one irradiation target area AR. The "monitoring value" is, for example, the power or illuminance of the light L2, or a deviation thereof.

In FIG. 6, the monitoring unit 40 is located in the irradiation target area AR, but it may be located near the other end T2. Also, in FIG. 6, there is one monitoring unit 40, but multiple units may be placed within the irradiation target area AR to detect illuminance deviations and power deviations.

The monitoring unit 40 notifies the optical coupling unit 11d of the monitoring value of the light L2. Here, the monitoring unit 40 may also notify the optical coupling unit 11d of the required value (e.g., power, illuminance, or deviation thereof) required by the irradiation target area AR.

The optical coupling unit 11d compares the monitoring value notified by the monitoring unit 40 with the required value required by the irradiation target area AR, and adjusts the coupling state so that the monitoring value becomes the required value. Note that "so that the monitoring value becomes the required value" has the following meaning.
(1) Matching the monitored value with the required value.
(2) If the monitored value cannot be made to match the required value (for example, due to power deviation), the difference between the monitored value and the required value is reduced.

(Embodiment 3)
7 is a diagram for explaining an optical transmission system 303 of this embodiment. In the optical transmission system 303, the bundle optical fiber 36 is disassembled at the other end T2 of the optical transmission system 301 of FIG. 4, and each single-core optical fiber 51a is wired to each irradiation unit 13 as a route 14. A monitoring unit 40 is further provided in each irradiation target area ARn, and the monitoring value of the light L2 irradiated from each irradiation unit 13 to each irradiation target area ARn monitored by each monitoring unit 40 is fed back to the optical coupling unit 11d. Note that the "monitoring value" is, for example, the power or illuminance of the light L2. Note that, in FIG. 7, the monitoring unit 40 exists in all irradiation target areas ARn, but may be disposed only in some irradiation target areas.

The monitoring unit 40 notifies the optical coupling unit 11d of the monitoring value of the light L2. Here, each monitoring unit 40 may also notify the optical coupling unit 11d of the required value (e.g., power or illuminance) required by the irradiation target area ARn. The optical coupling unit 11d compares the monitoring value notified from each monitoring unit 40 with the required value required by the irradiation target area ARn, and adjusts the coupling state so that the monitoring value becomes the required value. Alternatively, the optical coupling unit 11d adjusts the coupling state so that the monitoring values notified from each monitoring unit 40 are uniform or have the desired deviation.

Here, "so as to be even" has the following meaning.
(1) All monitored values must be the same.
(2) If the monitored values cannot be made uniform (for example, due to power deviation), reduce the variance of the monitored values.
Moreover, "so as to have a desired deviation" has the following meaning.
The "desired deviation" means that the power or illuminance of the light L2 is different for each irradiation target area or for each group of irradiation target areas (for example, AR1 to AR5 are strong illuminance, AR6 to AR10 are medium illuminance, and AR11 to AR20 are no irradiation, etc.).
(1) Matching the deviation of the monitored value to a desired deviation.
(2) If the deviation of the monitored value cannot be made to coincide with the desired deviation, the difference between the deviation of the monitored value and the desired deviation is reduced.

(Embodiment 4)
Fig. 8 is a diagram illustrating an optical transmission system 304 according to the present embodiment. The optical transmission system 304 is different from the optical transmission system 303 in Fig. 7 in that a monitoring unit 40 is connected to the tip of one or more specific paths 14, and the monitoring unit 40 is not present in the irradiation target area ARn.

Similar to the optical transmission system 303 in FIG. 7, the optical transmission system 304 is configured to feed back the monitoring value of the light L2 monitored by the monitoring unit 40 to the optical coupling unit 11d. The optical coupling unit 11d compares the monitoring value notified from one or more monitoring units 40 with the required value required by the irradiation target area ARn, and adjusts the coupling state so that the monitoring value becomes the required value. Alternatively, the optical coupling unit 11d adjusts the coupling state so that the monitoring values notified from each monitoring unit 40 are uniform or have the desired deviation.

The optical transmission system 304 may also be operated as follows.
The optical transmission system 304 also utilizes the power deviation when the ultraviolet light from the light source unit 11, which is an LED, is coupled at one end T1 of the bundle optical fiber 36, and utilizes (for example, inactivates) the high-power light propagating through the single-core optical fiber 51a near the center for the irradiation target area, and monitors the low-power light propagating through the single-core optical fiber 51a near the outer periphery by the monitoring unit 40. With such a configuration, the light coupled to the single-core optical fiber 51a with low power can be used to grasp the light propagation state without being wasted, ensuring safety, and there is no need to install a new device for ensuring safety, thereby reducing system costs.

Furthermore, the optical transmission system 304 feeds back monitoring information (whether or not light is propagating, or the power and illuminance of light) from the monitoring unit 40 to the optical coupling unit 11d. Communication from the monitoring unit 40 to the optical coupling unit 11d may be wired or wireless. The optical coupling unit 11d can perform the following controls based on the monitoring information.
(1) If the light power is greater than the required value, the size of the spot shape of the light L1 is expanded (the illuminance at one end T1 decreases, and the power of the ultraviolet light coupled to the single-core optical fiber 51a decreases), the optical axis of the light L1 and the bundle optical fiber 36 is shifted, or the light is blocked by a shutter, a filter, or the like.
(2) If the light power is smaller than the desired value, narrow the size of the spot shape of the light L1 (the illuminance at one end T1 increases, and the power of the ultraviolet light coupled to the single-core optical fiber 51a increases), align the optical axes of the light L1 and the bundle optical fiber 36, or open a shutter, a filter, or the like.

By operating in this manner, the optical transmission system 304 can ensure the safety of the entire system. Furthermore, since the optical transmission system 304 can vary the optical power to the irradiation target area, it is possible to shorten the irradiation time according to the conditions of the irradiation target area, reducing the waste of optical power and enabling the power consumption of the light source unit 11 to be reduced. In other words, the optical transmission system 304 makes it possible to reduce costs during system design and operation.

(Embodiment 5)
Fig. 9 is a diagram for explaining an optical transmission system 305 of this embodiment. The optical transmission system 305 is different from the optical transmission system 304 of Fig. 8 in that the feedback is performed using at least one of the multiple single-core optical fibers 51a of the bundle optical fiber 36. Here, the single-core optical fiber 51a used for the feedback is preferably arranged on the outer periphery in the cross section of the bundle optical fiber 36.

In the optical transmission system 305, the single-core optical fibers 51a included in the bundle optical fiber 36 that are not used for light propagation or monitoring by the monitoring unit 40 are used for communication, and connect the monitoring unit 40 to the optical coupling unit 11d. Here, the monitoring unit 40 may be one or more, and therefore the single-core optical fibers 51a for communication may also be one or more.

Also, from the other end T2 to the monitoring unit 40, the single-core optical fiber 51a for optical monitoring and the single-core optical fiber 51a for communication may be installed together like a tape line and operated. In this way, there is no need to prepare a separate communication line (optical fiber cable or other communication means such as wireless) for feedback to the optical coupling unit 11d, so the cost of the entire system can be reduced. Also, if the irradiation target area and the monitoring unit 40 are installed in the same location, the single-core optical fiber 51a for optical propagation, optical monitoring, and communication can be tape-connected, further reducing the cost of system operation and management.

Other Embodiments
In the above-described embodiment, the light source unit 11 is an LED. However, in the present invention, the light source unit 11 is not limited to an LED, and may be a light source (for example, an incandescent lamp or a discharge lamp) having the following optical characteristics.
- There is variation in wavelength, amplitude, or phase.
・Light is scattered.
・It is a natural release.

(effect)
The optical transmission system of this embodiment has the following features.
This optical transmission system includes an optical coupling unit 11d that utilizes the power deviation of the light L1 from the light source unit 11 having optical characteristics such as an LED, or a more pronounced power deviation, to adjust the coupling state of the light L1 to the bundle optical fiber 36 so as to have desired characteristics. The optical coupling unit 11d may be a mechanism that mechanically adjusts the coupling state based on position information of both the light source unit 11 and the bundle optical fiber 36, or may be configured by an optical system (a condenser lens, a wide-angle lens, a beam splitter, a prism, a mirror, etc.).

The "desired characteristics" include, for example, uniformity of the optical power supplied to multiple irradiation target areas, fairness in response to the requirements of each irradiation target area, shortening the time for supplying light, a combination of these characteristics (fairness and shortening), or priority control of the irradiation target areas. The optical coupling unit 11d adjusts the coupling state according to such desired characteristics, so that the present optical transmission system can achieve the desired characteristics. In other words, light from a light source unit with optical characteristics such as an LED is coupled to the bundle optical fiber in accordance with the characteristics desired by the irradiation target area, so that fairness for the irradiation target area can be achieved and waste during coupling can be reduced.

(supplement)
In this embodiment, the shape (spot) of the light L1 on a plane perpendicular to the optical axis is expressed as a circle. However, the spot of the light L1 is not limited to a circle. There are also cases where the spot of the light L1 emitted by the light source unit 11 has a shape other than a circle (for example, an ellipse or a polygon). Since the present invention includes such cases, the above-mentioned "spot shape" includes a circle and a shape other than a circle.

11: Light source unit 11a: Ultraviolet light source unit 11c: Optical system 11d: Light combining unit 12: Light distribution unit (equal branching)
13, 13-1, ..., 13-n, ..., 13-N: Irradiation unit 14: Path (each single-core optical fiber 51a bundled in the bundle optical fiber 36)
16: Optical transmission path 36: Bundle optical fiber 40: Monitoring unit 51a: Single-core optical fibers 301 to 305: Optical transmission system L1, L2: Light Lc: Size of optical spot AR1, AR2, ..., ARn, ..., ARN: Irradiation target area

Claims

A light source unit that outputs light;
an optical transmission line that propagates the light through a plurality of cores of an optical bundle formed by bundling a plurality of single-core optical fibers;
an optical coupling unit that causes the light output from the light source unit to enter the multiple cores;
An optical transmission system comprising:
The optical coupling unit includes:
an optical transmission system comprising: arbitrarily adjusting a coupling state in which the light is incident on the cores; and, as the adjustment of the coupling state, adjusting a spot shape of the light between a size that includes all of the multiple cores and a size that includes only one of the multiple cores.
The optical transmission system according to claim 1, characterized in that the optical coupling unit adjusts the coupling state while aligning the optical axis of the light with the central axis of the bundle optical fiber.
The optical transmission system according to claim 1, characterized in that the optical coupling unit adjusts the coupling state while shifting the optical axis of the light from the central axis of the bundle optical fiber.