Patent Application
20250004214
The present disclosure relates to an optical transmission system having a point-to-multipoint (P-MP) configuration for propagating light from one light source to a plurality of irradiation target regions.
For the purpose of preventing infectious diseases, there is an increasing demand for systems for sterilization and inactivation of viruses using ultraviolet light. Systems have three major categories of products. In the present specification, when the term “sterilization or the like” is used, it means sterilization and inactivation of viruses.
The product of NPL 1 is an autonomous mobile robot for emitting ultraviolet light. The robot emits ultraviolet light while moving in a room in a building such as a hospital room, thereby automatically achieving sterilization or the like over a wide range without human intervention.
The product of NPL 2 is a device that is installed on a ceiling or at a predetermined place in a room, and performs sterilization or the like while circulating the air in the room. Since the device does not directly emit ultraviolet light and does not affect the human body, highly safe sterilization or the like can be performed.
The product of NPL 3 is a portable device equipped with an ultraviolet light source. A user can transport the device to a desired area and irradiate the area with ultraviolet light. Thus, the device can be used in various places.
However, the devices described in NPL 1 to NPL 3 have the following problems.
The product of NPL 1 emits high-output ultraviolet light, and thus the device becomes large-scaled and expensive. Therefore, the product of NPL 1 has a problem that it is difficult to achieve an economical system.
In the product of NPL 1, since the ultraviolet light irradiation site is limited to a place where the robot can move/enter, it is difficult to emit the ultraviolet light to small places or recessed places.
Since the product of NPL 2 sterilizes the circulated indoor air or the like, it is not possible to directly emit ultraviolet light to a place to be sterilized.
The product of NPL 3, for example, cannot emit ultraviolet light to narrow pipes or areas where people cannot enter. Thus, the products of NPL 1 to NPL 3 have a problem in versatility of being able to emit ultraviolet light to any place.
The product of NPL 3 is portable and can emit ultraviolet light at various places. However, in order to obtain a sufficient effect such as sterilization at a target location, a user is required to have skills or knowledge, and there is a problem in operability.
To solve these problems, an ultraviolet light irradiation system 300 using an optical fiber as illustrated in
On the other hand, there are problems as illustrated in
The above-mentioned problems are not limited to ultraviolet light, and are the same for infrared light and visible light. Accordingly, in order to solve the problems, it is an object of the present invention to provide an optical transmission system capable of reducing system costs and reducing waste of output power of a light source.
In order to achieve the above object, the optical transmission system according to the present invention uses a light source such as an LED as a light source part, and propagates light from the light source part by a spatial multiplex transmission method such as a bundled single-core optical fiber or multi-core optical fiber.
Specifically, an optical transmission system according to the present invention includes:
The optical system narrows down a spot shape of the light to a size including all of the plurality of cores in an optical axis direction as the adjustment of the coupling state.
Here, the light source part may be an ultraviolet light source part having a light emitting diode (LED) that outputs ultraviolet light as the light. The optical system may be configured to narrow down a spot shape of the ultraviolet light output from the LED to a size including all the plurality of cores in an optical axis direction, and to cause the ultraviolet light to enter the plurality of cores.
Since this optical transmission system employs a light source such as an LED as the light source part, the system cost can be reduced compared with an optical transmission system employing a laser as the light source part.
In addition, this optical transmission system employs a multi-core optical fiber or a bundle optical fiber (a bundle of a plurality of single-core optical fibers) as an optical transmission line. Since the light source part is a light source such as an LED, the spot shape of the ultraviolet light cannot be narrowed down to the diameter of a single core by an optical system, but the waste of the output power of the light source part can be reduced by causing the light which has not been narrowed down to enter a plurality of cores disposed in a light collecting region.
Therefore, the present invention can provide an optical transmission system capable of reducing system costs and reducing waste of output power of the light source part.
The optical transmission system according to the present invention further includes irradiation parts that irradiate a plurality of irradiation target regions with the light propagated through the plurality of cores, respectively. When the light source part side of the optical transmission line is taken as one end, an optical distribution part (fan-out device) is disposed at the other end of the optical transmission line, and a P-MP configuration for delivering and emitting light to a plurality of irradiation target regions can be employed.
The optical transmission system according to the present invention further includes a monitoring part that monitors propagation of the light with respect to at least one of the cores.
When the propagating light is light other than visible light, it is difficult to visually check whether or not the light is being propagated. Therefore, by installing a monitoring part capable of detecting light in any of the cores, it is possible to easily ascertain whether the optical transmission system is in operation (in a state in which light is being propagated) or idle (in a state in which light is not being propagated).
It is preferable that the core monitored by the monitoring part be the core disposed on an outer periphery in a cross section of the optical transmission line.
Even if the coupling state is adjusted by the optical system, it is difficult to obtain uniform power in all the cores of the optical transmission line, and power deviation usually occurs. For example, in the cross section of the optical transmission line, although light having high power propagates through the cores near the center, light having low power propagates through the cores of the outer peripheral portion. The light propagating through the core of the outer peripheral portion has low power and may not be usable at the light irradiation destination (irradiation target region) (for example, when the light is ultraviolet light, the power is too small to sufficiently inactivate the irradiation target region).
Therefore, if monitoring is performed using the light propagating through the core of the outer peripheral portion, which cannot be used in the irradiation target region, it is possible to effectively use the light that has been propagated wastefully.
The optical transmission system according to the present invention further includes a control part that performs feedback control on at least one of power of the light output from the light source part and the coupling state adjusted by the optical system so that power of the light monitored by the monitoring part becomes a desired value.
By performing feedback control by the control part, it is possible to supply light of a power desired for the irradiation target region.
Here, the control part can perform the feedback control using at least one of the cores. Further, it is preferable that the core used for the feedback control be the core disposed on the outer periphery in a cross section of the optical transmission line.
The feedback control may be performed by wire or wirelessly, or may be performed by optical communication using the core of the optical transmission line. In this case, if the core of the outer peripheral portion of the optical transmission line that cannot be used in the irradiation target region due to the low light power is used for optical communication as described above, the resources can be effectively used.
Note that the above inventions can be combined to any extent possible.
The present invention can provide an optical transmission system capable of reducing system costs and reducing waste of output power of a light source.
Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. Constituent elements with the same reference numerals in the present specification and the drawings represent the same constituent elements. Further, in the present embodiment, a case where a light source part outputs ultraviolet light will be described, but the same is true for a case where the light source part outputs infrared light or visible light.
The ultraviolet light source part 11a includes an LED, and outputs light in an ultraviolet region (ultraviolet light) that is effective for sterilization or the like with the LED. The optical system 11c collects the ultraviolet light output from the ultraviolet light source part 11a to reduce the beam diameter. For example, the optical system 11c is a lens designed for wavelengths in the ultraviolet region.
The optical system 11c is not limited to narrowing down the beam diameter of a circular shape on a plane perpendicular to the optical axis up to the diameter of a circle including all of the plurality of cores in the optical axis direction. When the shape of light emitted from the ultraviolet light source part 11a on a plane perpendicular to the optical axis is a spot shape other than a circle (for example, an elliptical shape, a polygonal shape), the optical system 11c also narrows down the light to a size including all of the plurality of cores in the optical axis direction.
This optical fiber has one solid core 52 having a refractive index higher than that of a clad 60 in the clad 60. “Solid” means “not hollow.” The solid core can also be realized by forming an annular low refractive index region in the clad.
This optical fiber has a solid core 52 and a plurality of holes 53 disposed on the outer periphery of the solid core 52 in a clad 60. The medium of the hole 53 is air, and the refractive index of the air is sufficiently smaller than that of quartz glass. Therefore, the hole-assisted optical fiber has a function of returning light leaking from the core 52 by bending or the like to the core 52 again, and has a characteristic of small bending loss.
This optical fiber has a hole group 53a of a plurality of holes 53 in a clad 60, and has a refractive index effectively lower than that of a host material (glass or the like). This structure is called a photonic crystal fiber. This structure can have a structure in which a high refractive index core having a changed refractive index is not present, and light can be confined by making a region 52a surrounded by the holes 53 an effective core region. As compared with an optical fiber having a solid core, the photonic crystal fiber can reduce the influence of absorption and scattering loss of the core by an additive, and can realize optical characteristics which cannot be realized by the solid optical fiber such as reduction of bending loss and control of nonlinear effect.
The core region of this optical fiber is formed of air. Light can be confined in the core region by taking a photonic band gap structure by a plurality of holes or an anti-resonant structure by a glass thin wire in the cladding region. The optical fiber has a small nonlinear effect and can supply a high output or high energy laser.
In this optical fiber, a plurality of solid cores 52 having a high refractive index are disposed in close proximity to each other in a clad 60. The optical fiber guides light by light wave coupling between the solid cores 52.
Since the light can be dispersed and sent by the number of cores, there is an advantage that the power can be increased by that amount and efficient sterilization or the like can be performed, or the deterioration of the fiber due to ultraviolet light can be relaxed and the service life can be prolonged.
As the multi-core optical fiber 51b described above, optical fibers having a cross-sectional structure as illustrated in (6) to (10) in
In this optical fiber, a plurality of solid cores 52 having a high refractive index are disposed apart from each other in a clad 60.
This optical fiber guides light in a state where the influence of the light wave coupling can be ignored by sufficiently reducing the light wave coupling between the solid cores 52. There is an advantage that each core can be treated as an independent waveguide.
This optical fiber has a structure in which a plurality of the hole structures and core regions of the above (2) are disposed in a clad 60.
This optical fiber has a structure in which a plurality of the hole structures of the above (3) are disposed in a clad 60.
This optical fiber has a structure in which a plurality of the hole structures of the above (4) are disposed in a clad 60.
This optical fiber has a structure in which a plurality of the coupled core structures of the above (5) are disposed in a clad 60.
In the optical transmission system 301 of the present embodiment, the system cost can be reduced by using an LED as the light source, and the waste of the output power of the light source can be reduced by receiving and transmitting the ultraviolet light of a beam diameter which cannot be narrowed down by the optical system with a plurality of cores.
An optical distribution part 12-9 is disposed at the other end of the optical transmission line 26. The optical distribution part 12-9 outputs the ultraviolet light transmitted through each core of the optical transmission line 26 to a path 14 connected to each output port. Specifically, if the optical transmission line 26 is a bundle optical fiber, the optical distribution part 12-9 is a part where the bundled single-core optical fibers are disassembled, and the disassembled single-core optical fibers become the paths 14.
If the optical transmission line 26 is a multi-core optical fiber, the optical distribution part 12-9 is, for example, a fine-in/fan-out device disclosed in Reference 1. A multi-core optical fiber is connected to the fan-in side of the fine-in/fan-out device, and a path 14 is connected to the fan-out side.
The path 14 propagates the ultraviolet light distributed by the optical distribution part 12-9 to each irradiation part 13. The path 14 is a single-core optical fiber. Since the optical fiber is used, the optical fiber can be laid even in a small place where a robot and a device of the related art cannot enter. A single-core optical fiber having structures (1) to (5) in
The irradiation part 13 irradiates a predetermined target location (irradiation target region AR) to be sterilized or the like with the ultraviolet light transmitted through the path 14. The irradiation part 13 is constituted of an optical system such as a lens designed for the wavelength of ultraviolet light.
Since the optical transmission system 302 includes the optical distribution part 12-9 in comparison with the optical transmission system 301 of Embodiment 1, the system configuration of P-MP with a common light source can be achieved, and the system cost can be further reduced.
An optical transmission system that transmits ultraviolet light as light will be described.
(1) The optical transmission system has a point-to-multipoint configuration in which individual single-core optical fibers 51a bundled in the bundle optical fiber 36 are disassembled at the other end T2 (corresponding to the optical distribution part 12-9 in
(2) Also, power deviation occurs at one end T1 of the bundle optical fiber 36 to which the ultraviolet light is coupled. Specifically, in the cross section of the bundle optical fiber 36, ultraviolet light having high power is propagated through the single-core optical fiber 51a near the center, and ultraviolet light having low power is propagated through the single-core optical fiber 51a at the outer peripheral portion. Therefore, the use of the single-core optical fiber 51a in the outer peripheral portion is limited to the use of the single-core optical fiber 51a near the center, and there is a problem that resources are wasted, such as not using propagated ultraviolet light depending on design. Moreover, even if there is ultraviolet light that is not used, it is difficult to reduce the power consumption of the ultraviolet light source part 11a, and as a result, there is also a problem that it is difficult to reduce the cost of the optical transmission system.
Therefore, the present embodiment has been made to solve the above problems, and an object thereof is to provide an optical transmission system capable of ensuring safety even when propagating ultraviolet light, and reducing costs by eliminating waste of resources.
The single-core optical fiber 51a monitored by the monitoring part 40 is preferably a single-core optical fiber 51a disposed on the outer periphery in the cross section of the bundle optical fiber 36. A power deviation when ultraviolet light from the light source part 11a as an LED is coupled at one end T1 of the bundle optical fiber 36 is used, the ultraviolet light having high power propagated through the single-core optical fiber 51a near the center part is used to inactivate an irradiation target region, and the ultraviolet light having low power propagated through the single-core optical fiber 51a near the outer peripheral portion is monitored by the monitoring part 40. With such a configuration, the ultraviolet light coupled to the single-core optical fiber 51a having low power is used for ascertaining the propagation state of the ultraviolet light without wasting the ultraviolet light, and safety can be ensured, and the system cost can be reduced without installing a new device for ensuring safety.
The optical transmission system 304 also uses power deviation when ultraviolet light from the light source part 11a as an LED is coupled at one end T1 of the bundle optical fiber 36, uses the ultraviolet light having high power propagated through the single-core optical fiber 51a near the center part to inactivate an irradiation target region, and causes the monitoring part 40 to monitor the ultraviolet light having low power propagated through the single-core optical fiber 51a near the outer peripheral portion. With such a configuration, the ultraviolet light coupled to the single-core optical fiber 51a having low power is used for ascertaining the propagation state of the ultraviolet light without wasting the ultraviolet light, and safety can be ensured, and the system cost can be reduced without installing a new device for ensuring safety.
Further, the optical transmission system 304 feeds back monitoring information (whether or not ultraviolet light is propagating, or the power and illuminance of the ultraviolet light) in the monitoring part 40 to the control part 15. Communication from the monitoring part 40 to the control part 15 may be wired or wireless. The control part 15 can perform the following controls on the ultraviolet light source part 11a on the basis of the monitoring information.
(1) When the power of the ultraviolet light is greater than a desired value, an instruction is issued to suppress or stop the output of the ultraviolet light L1.
(2) When the power of the ultraviolet light is smaller than a desired value, an instruction is issued to increase the output of the ultraviolet light L1.
The control part 15 can also perform the following controls on the optical system 11c on the basis of the monitoring information.
(1) When the power of the ultraviolet light is greater than a desired value, an instruction is issued to increase the size of the spot shape of the ultraviolet light L1 (to decrease the illuminance at one end T1 and decrease the power of the ultraviolet light coupled to the single-core optical fiber 51a), to shift the optical axes of the ultraviolet light L1 and the bundle optical fiber 36, or to block it with a shutter, a filter, or the like.
(2) When the power of the ultraviolet light is smaller than a desired value, an instruction is issued to reduce the size of the spot shape of the ultraviolet light L1 (to increase the illuminance at one end T1 and increase the power of the ultraviolet light coupled to the single-core optical fiber 51a), to align the optical axes of the ultraviolet light L1 and the bundle optical fiber 36, or to open a shutter, a filter, or the like.
The optical transmission system 304 is provided with the control part 15, thereby ensuring the safety of the entire system. In addition, since the optical transmission system 304 can vary the power of the ultraviolet light to the irradiation target region, the irradiation time can be shortened according to the situation of the irradiation target region, and the waste of the ultraviolet light power can be reduced to save the power of the ultraviolet light source part 11a. In other words, the optical transmission system 304 enables cost reduction during system design and operation.
The optical transmission system 305 connects the monitoring part 40 and the control part 15 by using those of the single-core optical fiber 51a included in the bundle optical fiber 36 that are not used for the propagation of the ultraviolet light and the monitoring of the monitoring part 40 for communication. Here, since one or a plurality of monitoring parts 40 may be provided, one or a plurality of single-core optical fibers 51a for communication may be provided.
Further, the single-core optical fiber 51a for monitoring ultraviolet light and the single-core optical fiber 51a for communication may be collectively installed and operated like a tape wire from the other end T2 to the monitoring part 40. Thus, since a communication line (an optical fiber cable or other communication means such as radio or the like) for feedback to the control part 15 is not separately prepared, the cost of the entire system can be reduced. In addition, when the irradiation target region and the monitoring part 40 are installed at the same location, by tape-forming the single-core optical fibers 51a for ultraviolet light propagation, ultraviolet light monitoring, and communication, the cost of system operation and management can be further reduced.
In the above embodiments, the case where the ultraviolet light source part 11a is an LED has been described. However, in the present invention, the ultraviolet light source part 11a is not limited to an LED, but may be a light source (for example, an incandescent lamp or a discharge lamp) having the following optical characteristics.
Although the above-described embodiments have been described with reference to an example in which the optical transmission system includes an ultraviolet light source part, the present invention is not limited to ultraviolet light. The light L1 from the light source part may be infrared light or visible light.
Note that the “spot shape” described in this specification is a concept including the “beam diameter.”
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/041492 | Nov 2021 | WO | international |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/042007 | 11/10/2022 | WO |
