Underwater power supply system, output device, light receiving device, and underwater power supply method

Abstract

This underwater power supply system comprises, for example: an output device having an output window through which laser light that is output into water is transmitted; and a light receiving device having an input window through which the laser light propagated underwater via the output window is transmitted, and a photoelectric conversion unit that converts the energy of the laser light transmitted through the input window into electric energy. The wavelength of the laser light propagated underwater may be 200 [nm] to 600 [nm] inclusive. The output device may be installed on a fixed body fixed to the bottom of water, and the light receiving device may be installed on a moving body that moves underwater or on water.

Description

Underwater power supply system, output device, light receiving device, and underwater power supply method

[0001] The present invention relates to an underwater power supply system, an output device, a light receiving device, and an underwater power supply method.

[0002] 2. Description of the Related Art Conventionally, a method for contactlessly supplying power underwater or in the sea by utilizing electromagnetic induction has been known (for example, see Patent Document 1).

[0003] Patent No. 6497813

[0004] In wireless power transfer using electromagnetic induction, the power transmitting coil and the power receiving coil must be placed close to each other and positioned precisely when transferring power. This requires a structure for precisely positioning the power transmitting coil and the power receiving coil, which can lead to problems such as increased manufacturing effort and cost, as well as increased labor and time required for power transfer. Furthermore, in a structure with coils, increasing the power transfer power requires increasing the number of coils, resulting in a trade-off between power transfer power, cost, and size. Additionally, because the conductivity of water and the ocean differs, the system design must be optimized for each, which contributes to increased manufacturing effort and cost.

[0005] Therefore, one object of the present invention is to provide a new and improved underwater power supply system, output device, light receiving device, and underwater power supply method that does not utilize electromagnetic induction.

[0006] The underwater power supply system of the present invention includes, for example, an output device having an output window through which laser light outputted toward underwater passes, an input window through which laser light propagated underwater via the output window passes, and a light receiving device having a photoelectric conversion unit that converts the energy of the laser light that passes through the input window into electrical energy.

[0007] In the underwater power supply system, the wavelength of the laser light propagating underwater may be not less than 200 [nm] and not more than 600 [nm].

[0008] In the underwater power supply system, the wavelength of the laser light propagating underwater may be equal to or greater than 400 [nm] and equal to or less than 550 [nm].

[0009] In the underwater power supply system, the wavelength of the laser light propagating underwater may be equal to or greater than 430 [nm] and equal to or less than 480 [nm].

[0010] In the underwater power supply system, the output device may be provided on a fixed body fixed to the bottom of the water, and the light receiving device may be provided on a mobile body that moves underwater or on the surface of the water.

[0011] In the underwater power supply system, the fixed body may be fixed directly to the bottom of the water.

[0012] In the underwater power supply system, the fixed body may be connected to an anchor portion fixed to the bottom of the water via a flexible connection portion.

[0013] In the underwater power supply system, the output device may have a laser light source that outputs laser light using power supplied via an electric wire in a cable connected to the output device, and the laser light output by the laser light source may be output from the output window.

[0014] In the underwater power supply system, laser light transmitted into the output device via an optical fiber in a cable connected to the output device may be output from the output window.

[0015] In the underwater power supply system, the optical fiber may include a hollow-core fiber.

[0016] In the underwater power supply system, the output device may have a wavelength conversion unit that converts the wavelength of the laser light transmitted through the optical fiber, and the laser light whose wavelength has been converted by the wavelength conversion unit may be output from the output window.

[0017] In the underwater power supply system, the output device may have a beam shaper that shapes the beam shape of the laser light, and the laser light whose beam shape has been shaped by the beam shaper may be output from the output window.

[0018] In the underwater power supply system, the output device may have an expansion unit that expands a beam diameter of the laser light output from the output window or the laser light before being output from the output window.

[0019] In the underwater power supply system, the output device may have a diffusion mechanism that releases bubbles into the water and diffuses the laser light output from the output window with the bubbles.

[0020] In the underwater power supply system, at least one of the output window and the input window may be provided with an anti-reflection coating.

[0021] In the underwater power supply system, the moving body may have a sensor that detects the laser light output from the output window, and a control mechanism that controls the movement of the moving body so that the light intensity received by the sensor becomes a predetermined value.

[0022] In the underwater power supply system, the fixed body may have a first base and a first movable part that is movably mounted relative to the first base and has at least the output window of the output device.

[0023] In the underwater power supply system, the moving body may have a second base and a second movable part that is movable relative to the second base and has at least the input window of the light receiving device.

[0024] In the underwater power supply system, the fixed body may have a cooling mechanism that uses water around the fixed body to cool at least a part of the power output device.

[0025] In the underwater power supply system, the cooling mechanism may cool a coolant that cools at least a part of the power output device by using the surrounding water.

[0026] The output device of the present invention is used in, for example, the underwater power supply system and has the output window.

[0027] The light-receiving device of the present invention is used in, for example, the underwater power supply system and has the input window.

[0028] The underwater power supply method of the present invention uses an underwater power supply system that includes, for example, an output device having an output window through which laser light is output underwater, an input window through which laser light output from the output window and propagated underwater is input, and a light receiving device having a photoelectric conversion unit that converts the energy of the laser light input to the input window into electrical energy, and transmits the laser light from the output device to the light receiving device underwater, and supplies power from the output device to the light receiving device by converting the energy of the laser light into electrical energy using the photoelectric conversion unit in the light receiving device.

[0029] In the underwater power supply method, the wavelength of the laser light propagating underwater may be 200 nm or more and 600 nm or less, the output of the laser light output from the output window may be 3000 W or more, and the distance between the output window and the input window underwater may be 12 m or less.

[0030] According to the present invention, for example, it is possible to provide a new and improved underwater power supply system, an output device, a light receiving device, and an underwater power supply method that do not utilize electromagnetic induction.

[0031] FIG. 1 is an exemplary schematic configuration diagram showing an output device and a light receiving device of an underwater power supply system according to a first embodiment. FIG. 2 is a graph showing the relationship between the wavelength of light and the light absorption rate by water. FIG. 3 is a graph showing the relationship between the underwater propagation distance and transmittance for each wavelength of light. FIG. 4 is an exemplary schematic configuration diagram of an underwater power supply system according to a first embodiment. FIG. 5 is an exemplary schematic configuration diagram of an underwater power supply system according to a second embodiment. FIG. 6 is an exemplary schematic configuration diagram of an underwater power supply system according to a third embodiment. FIG. 7 is an exemplary schematic configuration diagram of an underwater power supply system according to a fourth embodiment. FIG. 8 is an exemplary schematic configuration diagram of an underwater power supply system according to a fifth embodiment. FIG. 9 is an exemplary schematic configuration diagram of an underwater power supply system according to a sixth embodiment. FIG. 10 is an exemplary schematic configuration diagram of an underwater power supply system according to a seventh embodiment. FIG. 11 is an exemplary schematic configuration diagram of an underwater power supply system according to an eighth embodiment.

[0032] Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments described below, as well as the actions and results (effects) brought about by the configurations, are merely examples. The present invention can also be realized by configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

[0033] The following embodiments have similar components, and in the following description, the same reference numerals will be used to designate the similar components, and redundant explanations may be omitted.

[0034] Ordinal numbers may be assigned for convenience to distinguish between parts, components, etc., and do not indicate priority or order, nor do they specify numbers. Furthermore, each drawing is a schematic diagram, and the dimensions in the drawing may differ from the actual dimensions.

[0035] [First embodiment] [Configuration of output device and light-receiving device] Fig. 1 is a configuration diagram showing an output device 100 and a light-receiving device 200 of an underwater power supply system 1 according to an embodiment. As shown in Fig. 1, an underwater power supply system 1A (1) includes an output device 100A (100) and a light-receiving device 200A (200). In the underwater power supply system 1, the output device 100 outputs a laser beam L into water. The light-receiving device 200 receives the laser beam L output from the output device 100 into water and propagated within the water, and converts the energy of the received laser beam L into electrical energy. That is, the underwater power supply system 1 supplies power from the output device 100 to the light-receiving device 200 by means of the laser beam L.

[0036] [Output Device] The output device 100A (100) has a housing 101, an output window 102, an optical module 103, a control circuit 104, a drive circuit 105, an optical fiber 106, a holding component 107, an optical system 108, and a cooling mechanism 109.

[0037] The housing 101 houses an optical module 103, a control circuit 104, a drive circuit 105, an optical fiber 106, a holding component 107, an optical system 108, and a cooling mechanism 109. If the housing 101 itself is to be submerged in water, it must be watertight and pressure-resistant. The housing 101 may also house components and devices other than those described above.

[0038] The output window 102 is fitted, for example, in an opening provided in the housing 101, and transmits the laser light L output from inside the housing 101 into the water. The output window 102 may be coated with an anti-reflection coating to prevent the laser light L from being reflected back into the housing 101. The output window 102 may be an optical component such as a lens or a lens array. In this case, the output window 102 is an example of a magnifying portion.

[0039] The optical module 103 includes a laser light source therein. The laser light source outputs laser light in response to supplied power. The optical module 103 includes, for example, a plurality of laser light sources and a plurality of optical components that guide the laser light output from each laser light source to the optical fiber 106. The laser light source is, for example, a semiconductor laser such as a so-called direct diode laser, but is not limited to this.

[0040] Power is supplied from the outside to the optical module 103, the control circuit 104, the drive circuit 105, the pump 109b of the cooling mechanism 109, etc. via electrical wiring 300a in the cable 300. The control circuit 104 controls the drive circuit 105 so that the optical module 103 and the pump 109b of the cooling mechanism 109 perform predetermined operations.

[0041] The optical fiber 106 transmits the laser light output from the optical module 103 to the optical system 108. The holding component 107 holds the end of the optical fiber 106 and positions it at a predetermined position so that the optical fiber 106 is optically connected to the optical system 108 with a desired coupling efficiency.

[0042] The optical system 108 transmits the laser light between the end of the optical fiber 106 and the output window 102. The optical system 108 has, for example, a concave lens 108a that expands the beam diameter and a convex lens 108b that collimates the light from the concave lens 108a, thereby expanding the beam diameter of the laser light. In this case, the optical system 108 is an example of an expanding unit. The laser light from the optical system 108 is output into water after passing through the output window 102. Note that the configuration of the output device 100 is not limited to the example shown in FIG. 1 .

[0043] The cooling mechanism 109 includes a pipe 109a through which a refrigerant flows and a pump 109b for circulating the refrigerant in the pipe 109a. The pipe 109a is thermally connected to at least the heat-generating portion of the optical module 103. The housing 101 is also provided with a passage 101a for drawing in and circulating water surrounding the power output device 100, and a portion of the pipe 109a is in contact with the water in the passage 101a. The cooling mechanism 109 configured as described above transfers heat generated in the heat-generating portion of the optical module 103 to the refrigerant, and then transfers heat from the refrigerant to the water in the passage 101a. This allows the optical module 103 to be cooled. Temperature changes in the optical module 103 may cause a change in the wavelength of the laser light L. In this regard, according to this embodiment, the cooling mechanism 109 can suppress this change in the wavelength of the laser light L. Furthermore, by utilizing the water surrounding the power output device 100, the cooling mechanism 109 can be realized with a relatively simple configuration.

[0044] [Light-Receiving Device] The light-receiving device 200 includes a housing 201 , an input window 202 , a photoelectric conversion unit 203 , a storage battery 204 , and an operating unit 205 .

[0045] The housing 201 houses the components and devices that constitute the photoelectric conversion unit 203, the storage battery 204, and the actuation unit 205. If the housing 201 itself is to be placed in water, it is necessary to ensure watertightness and pressure resistance. Note that the housing 201 may house components and devices other than those mentioned above.

[0046] The input window 202 is fitted into, for example, an opening provided in the housing 201, and transmits the laser light L input from underwater into the housing 201. The input window 202 may be provided with an anti-reflection coating that prevents the laser light L from being reflected into the water. The input window 202 may be an optical component such as a lens or a lens array.

[0047] The photoelectric conversion unit 203 converts the energy of the laser light L transmitted through the input window 202 into electrical energy. The photoelectric conversion unit 203 is a so-called solar cell, such as an indium gallium phosphide (InGaP) solar cell or an amorphous silicon (a-Si) solar cell. The selection of the solar cell will be described later.

[0048] The storage battery 204 stores the electric energy obtained by the photoelectric conversion unit 203. The operating unit 205 is electrically or electronically operated by the power stored in the storage battery 204, and is, for example, an electric device such as a motor or an electronic device such as a computer.

[0049] [Wavelength of Laser Light] Figure 2 is a graph showing the light absorption rate by water according to the wavelength of light. As shown in Figure 2, the light absorption rate by water varies depending on the wavelength of light. The light absorption rate by water is lowest when the wavelength is approximately 470 to 480 [nm]. From the viewpoint of reducing the absorption rate of laser light L by water and increasing the propagation efficiency of laser light L, the wavelength of laser light L propagated in water is preferably 200 [nm] or more and 600 [nm] or less, more preferably 400 [nm] or more and 550 [nm] or less, and even more preferably 430 [nm] or more and 480 [nm] or less.

[0050] FIG. 3 is a graph showing the relationship between the underwater propagation distance and transmittance for each wavelength of light. As shown in FIG. 3, the longer the underwater propagation distance of the laser light L, i.e., the longer the distance between the output window 102 and the input window 202, the more laser light L is absorbed, resulting in a lower transmittance of the laser light L. From FIG. 3 , it can be seen that when using laser light L with a wavelength of 200 nm or more and 600 nm or less, the required power can be obtained in the light-receiving device 200 even when the distance between the output window 102 and the input window 202 is relatively long, such as 1 m or more. That is, according to this embodiment, compared to the electromagnetic induction method, the advantage is that the distance between the supplying device (output device 100) and the receiving device (light-receiving device 200) can be increased.

[0051] Specifically, as an example, when the wavelength of the laser light L is 450 nm and the distance between the output window 102 and the input window 202 is 1 m, the transmission loss in water is 10%. In this case, when the transmittance of the output window 102 and the input window 202 are each 98% and the conversion efficiency of the photoelectric conversion unit 203 is 25%, it has been found that when the output of the laser light L from the optical module 103 is 5000 W, approximately 1080 W of electrical energy can be obtained in the photoelectric conversion unit 203. Note that an optical fiber with a core diameter of 600 μm and a beam quality of 30 mm mrad can be used as the optical fiber 106, and a circular solar cell with a diameter of approximately 6 inches (approximately 15.24 cm) can be used as the photoelectric conversion unit 203. The optical system 108 may be configured as a so-called beam expander that expands the beam diameter from 600 μm to 6 inches.

[0052] As another example, when the wavelength of the laser light L is 450 nm and the distance between the output window 102 and the input window 202 is 10 m, the transmission loss in water is 40%. In this case, when the transmittance of the output window 102 and the input window 202 is 98%, respectively, and the conversion efficiency of the photoelectric conversion unit 203 is 25%, it has been found that the photoelectric conversion unit 203 can generate approximately 720 W of electrical energy for a 5000 W output of the laser light L from the optical module 103. Again, the optical fiber 106 can be an optical fiber with a core diameter of 600 μm and a beam quality of 30 mm mrad, and the photoelectric conversion unit 203 can be a circular solar cell with a diameter of approximately 6 inches. Again, a so-called beam expander configuration that expands the beam diameter from 600 μm to 6 inches can be used for the optical system 108.

[0053] As described above, it has been found that sufficient practical transmission efficiency can be obtained whether the distance between the output window 102 and the input window 202 is 1 m or 10 m. Through diligent research by the inventors, it has been found that the output of the laser light L from the output device 100 is preferably 3000 W or more, and that the distance between the output window 102 and the input window 202 is preferably 12 m or less, and more preferably 10 m or less.

[0054] Furthermore, the power conversion efficiency of the photoelectric conversion unit 203 differs depending on the wavelength of the laser light L. It is preferable to select the photoelectric conversion unit 203 that is optimal for the wavelength of the laser light L based on the quantum efficiency of the material itself, and for example, when the wavelength of the laser light L is 430 nm or more and 480 nm or less, it is preferable to use an amorphous silicon solar cell, and when the wavelength is 450 nm or more and 600 nm or less, it is preferable to use an indium gallium phosphide solar cell.

[0055] [Underwater Power Supply System] Fig. 4 is a schematic configuration diagram of the underwater power supply system 1A(1) of the first embodiment. In Fig. 4, the water W is, for example, sea water or lake water, but may also be water stored in a structure such as a pool or a dam.

[0056] 4, in this embodiment, the data transmitter 100A (100) is directly fixed to the bottom B of the water. In this case, the data transmitter 100 is an example of a fixed body 10. Power is supplied to the data transmitter 100 from the ground or the like via electrical wiring 300a in a cable 300 (see FIG. 1).

[0057] On the other hand, the light receiving device 200A (200) is provided on a moving body 20 that can move through water W. The moving body 20 is, for example, an underwater drone. In this case, the propulsion mechanism 206 of the moving body 20 is, for example, a screw, and the actuation unit 205 is, for example, a motor that rotates and drives the screw serving as the propulsion mechanism 206. Note that the actuation unit 205 may be something other than a motor, and the moving body 20 may be provided with multiple actuation units 205. Furthermore, the moving body 20 may be a moving body other than an underwater drone that moves through water W, or may be, for example, a moving body that moves on water W, such as a ship.

[0058] The output window 102 is provided, for example, on the upper part (top wall) of the fixed body 10 (output device 100), and the input window 202 is provided on the lower part (bottom wall) of the movable body 20. The movable body 20 moves to a position where the input window 202 faces the output window 102 at a predetermined distance and stops. When laser light L is output upward from the output window 102, the input window 202 is positioned above the output window 102. In this state, the laser light L is output from the output device 100 through the output window 102 into water W, propagates through the water W, and is input into the light-receiving device 200 through the input window 202. A photoelectric conversion unit 203 (see FIG. 1) in the light-receiving device 200 converts the energy of the laser light L into electrical energy. The electrical energy is stored in a storage battery 204 (see FIG. 1) and used to operate the operating unit 205. The direction in which the laser light L is output from the output window 102 is not limited to the upward direction, but may be the horizontal direction or an oblique direction.

[0059] As described above, in this embodiment, by utilizing photoelectric conversion of laser light, the distance between the supplying device (power output device 100) and the receiving device (light-receiving device 200) can be longer and the alignment precision requirements can be relaxed compared to the electromagnetic induction method. Therefore, the equipment for bringing the power output device 100 and the light-receiving device 200 closer to each other and positioning them can be simplified or eliminated, thereby further simplifying the configuration of the underwater power supply system 1 and thereby further reducing manufacturing effort and costs. Furthermore, the effort and time required for bringing the power output device 100 and the light-receiving device 200 closer to each other and positioning them can be reduced when supplying power.

[0060] Furthermore, in this embodiment, the wavelength of the laser light L is set to a wavelength that is not easily absorbed by water, that is, 200 nm or more and 600 nm or less, thereby enabling energy transmission with high transmission efficiency.

[0061] In this embodiment, in the power output device 100 in the water W, the optical module 103 having a laser light source outputs laser light L using power supplied via the electrical wiring 300a in the cable 300. If laser light is introduced into the power output device 100 from the ground or the like via an optical fiber housed in the cable 300, light loss occurs in the optical fiber, and therefore, it is necessary to take this light loss into consideration. In this regard, in the present embodiment, there is no need to take such light loss into consideration.

[0062] Second Embodiment FIG. 5 is a schematic diagram of an underwater power supply system 1B (1) according to a second embodiment. As shown in FIG. 5 , in this embodiment, a cable 300 is fixed to the bottom B of the water via an anchor 11. An output device 100B (100) serving as a fixed body 10 is connected to the anchor 11 via a tip 301, which is a part of the cable 300. When the fixed body 10 and the cable 300 of the underwater power supply system 1 are installed in the sea or a lake, they may be subjected to external forces due to ocean currents, lake currents, and waves. In such a case, if only the fixed body 10 is fixed to the bottom B of the water and the cable 300 is not fixed to the bottom B, the external force acting on the cable 300 may cause large stresses, particularly at the connection between the fixed body 10 and the cable 300, which may result in damage or breakage of the cable 300. In this regard, in the present embodiment, since the fixed body 10 is not fixed to the water bottom B, stress generated at the connection between the fixed body 10 and the cable 300 can be reduced, thereby preventing damage or breakage of the cable 300 at the connection. The tip portion 301 is flexible and is an example of a flexible connection portion. The fixed body 10 may be fixed to the water bottom B via a flexible connection portion other than the tip portion 301 of the cable 300, such as a wire, and anchor portions 11 that fix the flexible connection portion to the water bottom B. The cable 300 may also be fixed to the water bottom B by multiple anchor portions 11. The fixed body 10 may also be fixed to the water bottom B via multiple flexible connection portions and anchor portions 11.

[0063] Third Embodiment FIG. 6 is a schematic diagram of an underwater power supply system 1C (1) according to a third embodiment. As shown in FIG. 6 , in this embodiment, the power output device 100C (100) serving as the fixed body 10 includes a diffusion mechanism 110 that diffuses the laser light output from the output window 102. The diffusion mechanism 110 includes a nozzle 111 protruding from the housing 101, which emits bubbles Bb into the transmission path of the laser light L between the output window 102 and the input window 202 in the water W. The bubbles Bb are emitted closer to the output window 102 than the input window 202. The bubbles Bb are air bubbles, and the air is supplied from the ground to the power output device 100C via an air tube housed within the cable 300. An internal pressure sufficient to withstand water pressure is applied to the air tube. Multiple nozzles 111 are provided at substantially regular intervals around the output window 102. 6, the number of nozzles 111 is two, but the number of nozzles 111 may be three or more. With this configuration, the bubbles Bb can appropriately diffuse the laser light L, thereby expanding the beam diameter of the laser light L.

[0064] Fourth Embodiment FIG. 7 is a schematic diagram of an underwater power supply system 1D (1) according to a fourth embodiment. In this embodiment, laser light L is transmitted from an external device installed on land, for example, to a power output device 100D (100) serving as a fixed body 10 via an optical fiber 300b housed in a cable 300. In this case, the optical fiber 300b preferably includes, for example, a hollow-core fiber capable of suppressing propagation loss. The laser light L transmitted through the optical fiber 300b is output into the water W via an optical system 112 and an output window 102. The optical system 112 includes at least one optical component, such as a collimating lens or a magnifying lens that expands the beam diameter. This configuration eliminates the need for the optical module 103 and the cooling mechanism 109, thereby enabling the power output device 100D and the fixed body 10 to be more compact. Furthermore, since the output device 100D of this embodiment does not have the optical module 103 or the cooling mechanism 109, it can be constructed to be relatively lightweight, and is therefore suitable for being fixed to the bottom B of the water via a flexible connection part (and anchor part 11), as in the second embodiment.

[0065] Fifth Embodiment FIG. 8 is a schematic diagram of an underwater power supply system 1E (1) according to a fifth embodiment. In this embodiment, as in the fourth embodiment, laser light L is transmitted from an external device installed on land, for example, to the output device 100E (100) serving as the fixed body 10 via an optical fiber 300b housed in a cable 300. Therefore, this embodiment also achieves the same effects as the fourth embodiment. However, in this embodiment, the optical fiber 300b in the cable 300 transmits laser light with a longer wavelength than the output laser light L, for example, laser light with a wavelength of 940 nm or more and 960 nm or less. The wavelength conversion unit 113 converts the wavelength to 430 nm or more and 480 nm or less by passing the laser light through a second harmonic generation element equipped with a nonlinear optical crystal. This configuration allows transmission of longer-wavelength laser light through the optical fiber 300b, thereby reducing transmission loss in the optical fiber 300b. In addition, since a cheaper quartz-based optical fiber 300b can be used to transmit laser light with a wavelength of 940 nm or more and 960 nm or less, the overall cost of the underwater power supply system 1, including the optical fiber 300b and the cable 300, can be reduced.

[0066] Furthermore, this embodiment includes a beam shaper 114 that shapes the beam shape of the laser light L. The beam shaper 114 is, for example, a diffractive optical element (DOE). The beam shaper 114 can form the laser light L with an intensity distribution that increases the conversion efficiency in the photoelectric conversion unit 203 (see FIG. 1 ) of the light receiving device 200, for example, an intensity distribution that has little variation depending on the location on the light receiving surface of the photoelectric conversion unit 203. The laser light L, whose beam shape has been shaped by the beam shaper 114, propagates in water W. This configuration can further increase the energy conversion efficiency in the photoelectric conversion unit 203. The beam shaper 114 may be provided in the image output device 100 of the first to fourth embodiments. Furthermore, the output device 100E of this embodiment can be constructed to be relatively lightweight because it does not have the optical module 103 or the cooling mechanism 109, and is therefore suitable for being fixed to the bottom B of the water via a flexible connection part (and anchor part 11) as in the second embodiment.

[0067] [Sixth embodiment] Fig. 9 is a schematic configuration diagram of an underwater power supply system 1F(1) of a sixth embodiment. As shown in Fig. 9, in this embodiment, a moving body 20F(20) has a base 20a and a movable part 20b that is movable relative to the base 20a. The base 20a and the movable part 20b are connected via a movable mechanism 207. The base 20a is an example of a second base, and the movable part 20b is an example of a second movable part.

[0068] In this embodiment, the movable part 20b has the input window 202 and the photoelectric conversion part 203 of the light receiving device 200F (200). However, the movable part 20b may have other components. The moving direction of the movable part 20b is at least the direction in which the output window 102 and the input window 202 face each other, which in this embodiment is, for example, the up-and-down direction. The movable part 20b may be movable in multiple directions relative to the base 20a. In this case, the movable part 20b may be movable, for example, in a direction intersecting the direction in which the output window 102 and the input window 202 face each other.

[0069] If the entire movable body 20 were to be moved by the actuating unit 205 and the propulsion mechanism 206 in order to position the input window 202 relative to the output window 102, this could increase the effort and time required for positioning and could increase the energy consumption of the actuating unit 205. In this regard, according to this embodiment, the movable body 20 is first moved to roughly position the input window 202 relative to the output window 102, and then the movable unit 20b is moved relative to the base 20a by the moving mechanism 207, thereby making it possible to more accurately position the input window 202 relative to the output window 102. In other words, according to this embodiment, advantages such as faster positioning and lower energy consumption are obtained compared to when the input window 202 is positioned relative to the output window 102 by only moving the entire movable body 20.

[0070] Seventh Embodiment Fig. 10 is a schematic configuration diagram of an underwater power supply system 1G(1) of a seventh embodiment. As shown in Fig. 10, in this embodiment, a fixed body 10G(10) has a base 115. An output device 100G(100) is connected to the base 115 via a movable mechanism 116. The base 115 is an example of a first base, and the output device 100G is an example of a first movable part.

[0071] In this embodiment, the movement direction of the output device 100G is at least the direction in which the output window 102 and the input window 202 face each other, and in this embodiment, as an example, the vertical direction. Note that the output device 100G may be movable in multiple directions relative to the base 115. In this case, the output device 100G may be movable, for example, in a direction intersecting the direction in which the output window 102 and the input window 202 face each other.

[0072] This embodiment also achieves the same effects as the sixth embodiment. Specifically, moving the entire movable body 20 using the actuator 205 and the propulsion mechanism 206 to position the input window 202 relative to the output window 102 may increase the effort and time required for positioning and may increase the energy consumption of the actuator 205. In this regard, this embodiment first moves the movable body 20 to roughly position the input window 202 relative to the output window 102, and then moves the output device 100 relative to the base 115 using the movable mechanism 116. This allows the input window 202 to be more accurately positioned relative to the output window 102. This embodiment offers advantages such as faster positioning and lower energy consumption compared to positioning the input window 202 relative to the output window 102 by moving only the entire movable body 20. It is not necessary for the entire output device 100G to be the first movable part; at least a portion of the output device 100G, including the output window 102, may be the first movable part.

[0073] The movable mechanism 116 of this embodiment can more firmly support the optical fiber connection device 100 at each position, and is therefore suitable for moving and supporting a relatively heavy optical fiber connection device 100A having an optical module 103 (laser light source, laser oscillation mechanism) therein, such as the optical fiber connection device 100A of the first embodiment. The movable mechanism 116 may also be referred to as a non-flexible connection portion.

[0074] Eighth Embodiment FIG. 11 is a schematic diagram of an underwater power supply system 1H (1) according to an eighth embodiment. As shown in FIG. 11 , in this embodiment, the light-receiving device 200H (200) includes a sensor 208 that detects the laser light L output from the output window 102 and its surrounding light (diffused light), and a control circuit 209 that controls the operation of the actuator 205 based on the detected value of the sensor 208. In this embodiment, multiple sensors 208 are arranged around the input window 202. The control circuit 209 controls the operation of the actuator 205 to, for example, keep the received light intensity of all sensors 208 within a predetermined range, thereby moving the moving body 20. In this case, the control circuit 209 performs feedback control of the actuator 205 based on the detected values ​​of the sensors 208 so that all detected values ​​of the multiple sensors 208 fall within a predetermined range near the predetermined value. The control circuit 209 is an example of a control mechanism. This configuration reduces the effort and time required to position the input window 202 relative to the output window 102. In the configuration of the sixth embodiment, the sensor 208 may be provided around the input window 202 of the movable part 20b. Also, in the configuration of the sixth embodiment, the control mechanism may control the movable mechanism 207 in accordance with the detection value of the sensor 208 to move the movable part 20b (second movable part) and position the input window 202 with respect to the output window 102. Also, in the configuration of the seventh embodiment, the control mechanism may control the movable mechanism 116 in accordance with the detection value of the sensor 208 to move the output device 100G (first movable part) and position the input window 202 with respect to the output window 102.

[0075] While the above describes exemplary embodiments of the present invention, the above embodiments are merely examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be appropriately modified and implemented.

[0076] For example, the underwater power supply system may be configured as a system that supplies power from one mobile body to another mobile body, or a system that supplies power from a mobile body to a fixed body.

[0077] Furthermore, for example, the underwater power supply system may include a temporary holding mechanism that can temporarily maintain a relative positional relationship, such as the distance and direction, between the output window and the input window in a predetermined, suitable state when laser light from the fixed body is input to the movable body, i.e., in an energy supply state. The temporary holding mechanism may, for example, have a movable connecting member provided on at least one of the fixed body and the movable body. In this case, the temporary holding mechanism may be configured to switch between a temporary holding state in which the fixed body and the movable body are temporarily connected via the movable connecting member and a non-holding state (released state) in which the connection between the fixed body and the movable body by the movable connecting member is released. The movable connecting member may, for example, be configured to be movable between a connected position in which the fixed body and the movable body are temporarily connected and a released position in which the temporary connection between the fixed body and the movable body is released.

[0078] The present invention can be used in an underwater power supply system, an output device, a light receiving device, and an underwater power supply method.

[0079] DESCRIPTION OF SYMBOLS 1, 1A to 1H... Underwater power supply system 10, 10G... Fixed body 11... Anchor section 20, 20F... Moving body 20a... Base (second base) 20b... Movable section (second movable section) 100, 100A to 100E... Output device 100G... Output device (first base) 101... Housing 101a... Passage 102... Output window 103... Optical module (laser light source) 104... Control circuit 105... Drive circuit 106... Optical fiber 107... Holding part 108... Optical system 108a... Concave lens 108b... Convex lens 109... Cooling mechanism 109a... Piping 109b... Pump 110... Diffusion mechanism 111... Nozzle 112... Optical system 113... Wavelength conversion section 114... Beam shaper 115... Base (first base) 116... Movable mechanism 200, 200A, 200F, 200H... Light receiving device 201... Housing 202... Input window 203... Photoelectric conversion unit 204... Storage battery 205... Operating unit 206... Propulsion mechanism 207... Movable mechanism 208... Sensor 209... Control circuit 300... Cable 301... Tip (flexible connection part) 300a... Electrical wiring 300b... Optical fiber B... Bottom of water Bb... Bubbles L... Laser light W... Water

Claims

1. An underwater power supply system comprising: an output device having an output window through which laser light outputted toward underwater passes; and a light receiving device having an input window through which laser light propagated underwater via the output window passes, and a photoelectric conversion unit that converts the energy of the laser light that has passed through the input window into electrical energy.

2. An underwater power supply system as described in claim 1, wherein the wavelength of the laser light propagating underwater is equal to or greater than 200 nm and equal to or less than 600 nm.

3. An underwater power supply system as described in claim 2, wherein the wavelength of the laser light propagating underwater is not less than 400 nm and not more than 550 nm.

4. An underwater power supply system as described in claim 3, wherein the wavelength of the laser light propagating underwater is 430 nm or more and 480 nm or less.

5. The underwater power supply system according to claim 1, wherein the output device is provided on a fixed body fixed to the bottom of the water, and the light receiving device is provided on a moving body that moves underwater or on the surface of the water.

6. The underwater power supply system according to claim 5, wherein the fixed body is directly fixed to the bottom of the water.

7. The underwater power supply system according to claim 5, wherein the fixed body is connected to an anchor portion fixed to the bottom of the water via a flexible connection portion.

8. The underwater power supply system according to claim 1, wherein the output device has a laser light source that outputs laser light using power supplied via an electric wire in a cable connected to the output device, and the laser light output by the laser light source is output from the output window.

9. The underwater power supply system according to claim 1, wherein laser light transmitted into the output device via an optical fiber in a cable connected to the output device is output from the output window.

10. The underwater power supply system of claim 9, wherein the optical fiber comprises a hollow-core fiber.

11. The underwater power supply system according to claim 9, wherein the output device has a wavelength conversion unit that converts the wavelength of the laser light transmitted through the optical fiber, and the laser light whose wavelength has been converted by the wavelength conversion unit is output from the output window.

12. The underwater power supply system of claim 1, wherein the output device has a beam shaper that shapes the beam shape of the laser light, and the laser light whose beam shape has been shaped by the beam shaper is output from the output window.

13. An underwater power supply system as described in claim 1, wherein the output device has an expansion section that expands the beam diameter of the laser light output from the output window or the laser light before being output from the output window.

14. An underwater power supply system as described in claim 1, wherein the output device has a diffusion mechanism that releases bubbles into the water to diffuse the laser light output from the output window with the bubbles.

15. The underwater power supply system according to claim 1, wherein at least one of the output window and the input window is provided with an anti-reflection coating.

16. An underwater power supply system as described in claim 5, wherein the moving body has a sensor that detects the laser light output from the output window, and a control mechanism that controls the movement of the moving body so that the intensity of the light received by the sensor becomes a predetermined value.

17. The underwater power supply system according to claim 5, wherein the fixed body comprises a first base and a first movable part that is movably mounted on the first base and has at least the output window of the output device.

18. The underwater power supply system of claim 5, wherein the movable body has a second base and a second movable part that is movable relative to the second base and has at least the input window of the light receiving device.

19. The underwater power supply system according to claim 5, wherein the fixed body has a cooling mechanism that uses water around the fixed body to cool at least a part of the output device.

20. The underwater power supply system according to claim 19, wherein the cooling mechanism cools a coolant that cools at least a portion of the output device by the surrounding water.

21. An output device used in the underwater power supply system according to any one of claims 1 to 20, the output device having the output window.

22. A light receiving device used in the underwater power supply system according to any one of claims 1 to 20, comprising the input window and the photoelectric conversion section.

23. An underwater power supply method comprising: an output device having an output window through which laser light is output underwater; and a light receiving device having an input window into which laser light output from the output window and propagated underwater is input, and a photoelectric conversion unit that converts the energy of the laser light input to the input window into electrical energy, using an underwater power supply system, in which the laser light is transmitted from the output device to the light receiving device underwater, and the energy of the laser light is converted into electrical energy by the photoelectric conversion unit in the light receiving device, thereby supplying power from the output device to the light receiving device.

24. The underwater power supply method according to claim 23, wherein the wavelength of the laser light propagating underwater is 200 nm or more and 600 nm or less, the output of the laser light output from the output window is 3000 W or more, and the distance between the output window and the input window underwater is 12 m or less.

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