Photoelectric power generation system

Abstract

To provide an optical power supply system capable of efficiently supplying power to a distant light receiver.SOLUTION: An optical power supply system includes a laser light source, a light projector that projects a laser beam output from the laser light source toward a photoreceptor positioned far away and performing photoelectric conversion, and an adjustment mechanism that adjusts the light intensity distribution of the laser light projected onto the photoreceptor. The laser light source includes a plurality of laser devices, and the adjustment mechanism includes a delivery fiber, and an optical concentrator that inputs the laser light output from each of the laser devices into the delivery fiber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a photovoltaic power supply system.

Background Art

[0002] Techniques for using an aircraft as a next-generation communication base station or as an information communication base during a disaster have been disclosed (Patent Document 1). Further, as a method for supplying power to a remote moving body, a technique using photovoltaic power supply, which is a kind of wireless power supply, has been disclosed (Patent Document 2). The moving body is provided with a light receiver that performs photoelectric conversion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a photovoltaic power supply system capable of efficiently supplying power to a remote light receiver.

Means for Solving the Problems

[0005] To solve the above-described problems and achieve the object, one aspect of the present invention is a photovoltaic power supply system including a laser light source, a projector that projects laser light output from the laser light source toward a light receiver that is located remotely and performs photoelectric conversion, and an adjustment mechanism that adjusts the light intensity distribution of the laser light projected onto the light receiver.

[0006] The laser light source may include a plurality of laser devices, and the adjustment mechanism may include a delivery fiber and a light concentrator that inputs the laser light output from each of the laser devices into the delivery fiber.

[0007] The laser light source may include a plurality of laser devices, and the adjustment mechanism may include a plurality of output optical fibers that propagate the laser light output from the plurality of laser devices, and the plurality of output optical fibers may be arranged in a shape that matches the shape of the light receiver.

[0008] The laser light source may include a fiber laser or a fiber output laser diode.

[0009] The adjustment mechanism may include a direction adjustment mechanism that adjusts the divergence angle or the propagation direction of the projected laser light.

[0010] The adjustment mechanism may adjust the light intensity distribution of the laser light so that the light intensity distribution shape of the projected laser light becomes a flat top shape.

[0011] It may include a moving body on which the laser light source is mounted.

[0012] It may include the light receiver.

[0013] The light receiver may be mounted on an aircraft.

[0014] The aircraft may include a light receiving panel that receives sunlight and performs photoelectric conversion.

[0015] The aircraft may include an optical element that changes the propagation direction of the projected laser light, and the light receiving panel may receive the laser light with the changed propagation direction and the sunlight as the light receiver.

[0016] A light reception state detector for detecting the light reception state of the light receiver is provided, and the adjustment mechanism may adjust the divergence angle or the propagation direction of the laser light projected by the light projector based on the light reception state detected by the light reception state detector.

[0017] It may also be provided with an obstacle detector for detecting an obstacle between the light receiver and the laser light source, and a control unit for stopping or starting the output of the laser light based on the detection result of the obstacle detector.

[0018] The obstacle detector may detect an obstacle within a predetermined range including the beam of the projected laser light.

[0019] The obstacle detector may detect an obstacle within the range of the beam of the projected laser light.

Advantages of the Invention

[0020] The optical power supply system according to the present invention has the effect of being able to efficiently supply power to a remote light receiver.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited by the embodiments described below. Further, in the description of the drawings, the same parts are appropriately given the same reference numerals, and redundant explanations are omitted as appropriate.

[0023] (Embodiment) [Overall Configuration] FIG. 1 is a diagram showing the configuration of an optical power generation system according to an embodiment. The optical power generation system 1 includes a laser unit 2, a light projection unit 3, a sensor 4, a communicator 5, a vehicle 6, a vibration isolation / shock isolation device 7, and an aircraft F1 equipped with a light receiving panel P1 which is a light receiving body that performs photoelectric conversion.

[0024] The laser unit 2 includes a laser light source 21, a power supply device 22, a battery 23, and a chiller 24. The laser light source 21 outputs laser light. The power supply device 22 supplies the power stored in the battery 23 to the laser light source 21 and the chiller 24. The power supply device 22 controls the start and stop of the output of the laser light from the laser light source 21. The chiller 24 cools the laser light source 21.

[0025] The light projecting unit 3 includes a tracking device 31 and a projector 32. The tracking device 31 supports the projector 32 and controls the elevation angle and azimuth angle of the projector 32. The projector 32 projects the laser light output by the laser light source 21 onto the light receiving panel P1 of the flying object F1. The light receiving panel P1 can perform photoelectric conversion on the laser light and extract electric power. This electric power can be used as the electric power for operating the flying object F1. For effective power supply, the wavelength of the laser light may be made to coincide with the wavelength at which the light receiving sensitivity of the light receiving panel P1 is high. An example of the wavelength at which the light receiving sensitivity of the light receiving panel P1 is high is, for example, about 800 nm. There is also an example of selecting a wavelength band with small propagation loss in the atmosphere and capable of oscillation with a high-power fiber laser, which is 1000 - 1100 nm.

[0026] The tracking device 31 is an example of an adjustment mechanism for adjusting the light intensity distribution of the laser light projected onto the light receiving body (light receiving panel P1), and is also an example of a direction adjustment mechanism for adjusting the propagation direction of the projected laser light.

[0027] The sensor 4 is configured to be able to detect the position of the flying object F1. The sensor 4 includes, for example, LiDAR.

[0028] The communicator 5 is configured to be able to perform wireless communication with the communicator included in the flying object F1. The communicator 5 receives, for example, a communication signal including information on the light reception amount of the light receiving panel P1.

[0029] The tracking device 31 may be configured to be able to automatically track so that the amount of received laser light by the light receiving panel P1 becomes equal to or greater than a desired value based on the detection result of the sensor 4 and the communication signal received by the communicator 5.

[0030] The vehicle 6 mounts the laser unit 2, the light projecting unit 3, and the vibration isolation and shock isolation device 7 on the loading platform. The vehicle 6 is an example of a moving body. Thereby, the optical power supply system 1 can be moved.

[0031] The vibration isolation and shock isolation device 7 mounts the laser unit 2 and the light projecting unit 3. Thereby, since the vibrations of the laser unit 2 and the light projecting unit 3 are suppressed, the reliability of the laser unit 2 and the deterioration of the light projecting performance and the tracking performance of the light projecting unit 3 are suppressed.

[0032] [Configuration example of laser light source] FIG. 2 is a diagram showing a configuration example of the laser light source 21. The laser light source 21 includes 12 fiber lasers 211 which are a plurality of laser devices, and further includes a light concentrator 212 and a delivery fiber 213. The light concentrator 212 and the delivery fiber 213 constitute an example of an adjustment mechanism.

[0033] The fiber laser 211 includes a plurality of excitation light sources 211a, 211b such as laser diodes, light concentrators 211c, 211d, fiber Bragg gratings (FBGs) 211e, 211f, and an optical amplification fiber 211g.

[0034] The optical amplifier fiber 211g is a double-clad optical fiber having a single-mode core containing an optical amplification medium such as ytterbium (Yb). The excitation light sources 211a and 211b output excitation light having a wavelength capable of optically exciting the optical amplification medium, respectively. The wavelength of the excitation light is, for example, a wavelength included in the 900 nm band. The optical concentrators 211c and 211d input the excitation light from the excitation light sources 211a and 211b into the optical amplifier fiber 211g, respectively. As the optical concentrators 211c and 211d, for example, those of a type called a Tapered Fiber Bundle (TFB) can be used. The FBGs 211e and 211f act as resonator mirrors that pass the excitation light and reflect light at a wavelength included in the emission wavelength band of the optical amplification medium. As a result, the fiber laser 211 oscillates a laser at the reflection wavelength of the resonator mirror and outputs laser light. The laser oscillation wavelength is, for example, in the 1000 nm band with relatively little absorption in the atmosphere, for example, 1050 nm. When the laser light is single-mode, the optical intensity distribution shape of the laser light is Gaussian. Such laser light has an M 2 value of, for example, 1.05.

[0035] The optical concentrator 212 aggregates the laser light output from each of the 12 fiber lasers 211 and inputs it into the delivery fiber 213. The optical concentrator 212 is, for example, an integrated bundle of a plurality of fibers, and is tapered thinly in the emission direction like a TFB in order to adjust the size of the BPP (Beam Parameter Products) of the output light. As the optical concentrator, those that are not tapered or tapered to be thick in the emission direction can also be used.

[0036] The delivery fiber 213 is a multimode fiber and propagates the laser light from the laser unit 2 to the projector 32 of the light projecting unit 3. The delivery fiber 213 has a core diameter of, for example, 80 μm. At this time, the beam parameter product BPP of the laser light output from the delivery fiber 213 is, for example, 3.0 mm·mrad, and the M 2 value is, for example, 8.8.

[0037] The projector 32 is provided with a collimating lens optical system. The projector 32 collimates the laser light input from the delivery fiber 213 and projects it toward the light receiving panel P1 located far away (see beam B1 in Fig. 1). "Far away" means, for example, a distance from several hundred meters to several tens of kilometers.

[0038] [Example of projection state] Fig. 3 is a diagram showing an example of the projection state by the optical power generation system 1. Assume that the light receiving panel P1 has a circular shape and its diameter is 2 m. Assume that the light receiving panel P1 is located 20 km away from the optical power generation system 1 on the ground. 20 km corresponds to, for example, the case where the aircraft F1 equipped with the light receiving panel P1 is flying in the stratosphere. Assume that the focal length of the collimating lens optical system 32a provided in the projector 32 is 1000 mm. The diameter of the collimating lens optical system 32a is 150 mm, and the principal point is arranged at a distance L1 (for example, 1 m) corresponding to approximately the focal length from the end face of the delivery fiber 213 and separated from the fiber output end. Also, assume that the light intensity distribution shape BP1 of the laser light output from the delivery fiber 213 is a substantially Gaussian shape, and the light intensity distribution shape BP2 also reaches the light receiving panel P1 in a substantially Gaussian shape. The delivery fiber 213 shows the cross-sectional shape of the fiber end, and the core 213a has a diameter of, for example, 80 μm. A glass component called an end cap for end face protection is usually attached to the portion surrounded by the dashed line at the tip of the delivery fiber 213, but it is not shown here. The end cap may be a known one and has, for example, a frustum shape. End caps may also be appropriately provided on other delivery fibers and output fibers.

[0039] In this case, when projecting onto the light receiving panel P1 with a diameter of 2 m at a distance of 20 km, the desired divergence angle of the laser light is approximately 0.05 mrad. Assume that the power of the laser light output from the delivery fiber 213 is 6 kW. Then, due to atmospheric scattering and the like, the power is attenuated by about 50%, and about 3 kW of power reaches the light receiving panel P1. In this case, the light density of the laser light reaching is about 1 kW / m2 As a result, the center has a high density, and the power received by the light-receiving panel P1 is about 450 W.

[0040] In the light projection state shown in FIG. 3, the laser light is projected in a circular light intensity distribution shape on a plane perpendicular to the optical axis in accordance with the circular shape of the light-receiving panel P1, so that power supply can be performed relatively efficiently.

[0041] In the example of FIG. 3, the divergence angle of the laser light can be adjusted by the design of the collimating lens optical system 32a and the delivery fiber 213. The collimating lens optical system 32a and the delivery fiber 213 are an example of a direction adjustment mechanism for adjusting the divergence angle of the projected laser light.

[0042] FIG. 4 is a diagram showing an example of the light projection state by the optical power supply system 1. The difference from FIG. 3 is that the delivery fiber 213 is replaced with a delivery fiber 213A. The delivery fiber 213A outputs the light intensity distribution shape BP3 of the laser light output from the core 213Ac as a flat top shape, and it is assumed that the light intensity distribution shape BP4 also reaches the light-receiving panel P1 in a flat top shape. In order for the delivery fiber 213A to output a laser light with a flat top shape, known techniques such as a configuration using a special fiber can be applied. Incidentally, it is assumed that the focal length of the collimating lens optical system 32a provided in the projector 32 is 1000 mm. The diameter of the collimating lens optical system 32a is 150 mm, and the principal point is arranged at a distance L2 (for example, 1 m) corresponding to approximately the focal length from the end face of the delivery fiber 213A and separated from the fiber output end.

[0043] Also in the light projection state shown in FIG. 4, the laser light is projected in a circular light intensity distribution shape on a plane perpendicular to the optical axis in accordance with the circular shape of the light-receiving panel P1, so that power supply can be performed relatively efficiently.

[0044] Furthermore, assuming that the power of the laser beam output from the delivery fiber 213 is 6 kW as in FIG. 3, the power received by the light receiving panel P1 increased by approximately 500 W compared to the case of FIG. 3. Thus, it is preferable for efficient power supply that the light intensity distribution shape of the laser beam is a flat-top shape.

[0045] Here, the power generation amounts were compared between the case where the light intensity distribution shape of the laser beam is a Gaussian shape and the case where it is a flat-top shape. The power generation amount was calculated as the ratio to the case where the laser beam of the same power irradiates the light receiving panel with a uniform light density. The diameter of the light receiving panel was 50 cm. FIG. 5 is a diagram showing examples (cross-sectional shapes) of the intensity distribution shapes of the laser beams used for the comparison. Gaussian1 is a Gaussian shape with a full width at half maximum of 30 cm in the cross-sectional shape of the intensity distribution. Gaussian2 is a Gaussian shape with a full width at half maximum of 35 cm. Flat-top1 is a flat-top shape with a full width at half maximum of 35 cm, and the width of the cross-sectional shape of the flat region (the region where the ratio of the light intensity to the central light intensity is 90% or more) is 25 cm. Flat-top2 is a flat-top shape with a full width at half maximum of 40 cm, and the width of the flat region is 28 cm.

[0046] As a result, the power generation amounts were 71% for Gaussian1 and 60% for Gaussian2, whereas they were 88% for Flat-top1 and 74% for Flat-top2. It was confirmed that the flat-top shape has a larger power generation amount and is preferable for efficient power supply.

[0047] [Other Configuration Examples of Laser Light Sources] FIG. 6 is a diagram showing a configuration example of a laser light source. As shown in FIG. 6(a), the laser light source 21B includes seven laser devices 211B which are an example of a plurality of laser devices, a light concentrator 212B, and seven delivery fibers 213B.

[0048] Each laser device 211B has three fiber lasers 211 and includes an output fiber 211Ba and a light concentrator 211Bb. The output fiber 211Ba and the light concentrator 211Bb constitute an example of an adjustment mechanism. The output fiber 211Ba is a single-mode fiber that propagates the laser light output from each fiber laser 211 and outputs it to the light concentrator 211Bb. The light concentrator 211Bb concentrates the laser light from the three output fibers 211Ba and inputs it to the delivery fiber 213B. For example, a TFB can be used as the light concentrator 211Bb.

[0049] Each delivery fiber 213B is a multi-mode fiber that propagates the laser light from each light concentrator 212Bb in multi-mode and outputs the multi-mode laser light to the light concentrator 212B.

[0050] As shown in the end view seen from the projector 32B side in Fig. 6(b), the light concentrator 212B is composed of seven multi-mode fibers corresponding to the number of the laser devices 211B and the delivery fibers 213B bundled together. Each multi-mode fiber is connected to each delivery fiber 213B. In the light concentrator 212B, the seven multi-mode fibers are arranged in a triangular lattice with a closest-packing structure, forming a regular hexagonal shape or a circular shape as a whole. As a result, the light intensity distribution shape of the laser light output from the light concentrator 212B to the projector 32B becomes a pseudo-regular hexagonal shape or a circular shape.

[0051] The projector 32B collimates the laser light output from the light concentrator 212B and projects it toward a light receiving panel located far away. At this time, if the light receiving panel is in a regular hexagonal shape or a circular shape, power supply can be performed relatively efficiently.

[0052] When optical fibers are bundled together to form a light concentrator 212B, various light intensity distribution shapes of laser light can be formed depending on the bundling method. The light concentrator 212B is an example of a configuration in which a plurality of output fibers are arranged in a shape matching the shape of the light receiver.

[0053] Note that FIG. 6(c) is a light concentrator 212BA which is a modified example of the light concentrator 212B, and is an end view seen from the side of the projector 32B. The light concentrator 212BA is configured by bundling six multimode fibers. In the light concentrator 212B, the six multimode fibers are bundled so as to form a rectangular shape as a whole. As a result, the light intensity distribution shape of the laser light output from the light concentrator 212BA to the projector 32B becomes a pseudo-rectangular shape. At this time, if the light receiving panel is rectangular, power supply can be performed relatively efficiently.

[0054] [Example of light projection state] FIG. 7 is a diagram showing an example of a light projection state according to the configurations of FIGS. 6(a) and 6(b). Assume that the light receiving panel P1 has a circular shape and its diameter is 3 m. Assume that the light receiving panel P1 is located at a position 20 km away from the optical power supply system 1 on the ground. Assume that the focal length of the collimating lens optical system 32Ba provided in the projector 32B is 1000 mm. The diameter of the collimating lens optical system 32a is 200 mm, and the principal point is arranged at a distance L3 (for example, 1 m) corresponding to approximately the focal length from the end face of the light concentrator 212B and separated from the fiber output end. Assume that it is located at a distance of 1 m. Also, each of the multimode fibers constituting the light concentrator 212B has a core diameter of 80 μm, a beam parameter product BPP of 3.0 mm·mrad, and an M 2 value of 8.8. Also, assume that the light intensity distribution shape BP5 of the laser light output from the light concentrator 212B is a substantially regular hexagonal shape, and the light intensity distribution shape BP6 also reaches the light receiving panel P1 in a substantially regular hexagonal shape.

[0055] In this case, when projecting light onto the light receiving panel P1 with a diameter of 3 m at a distance of 20 km, the divergence angle of the laser light desired is about 0.05 mrad. Assume that the total power of the laser light output from the light concentrator 212B is 20 kW. Then, due to atmospheric scattering and the like, the power is attenuated by about 50%, and about 10 kW of power reaches the light receiving panel P1. In this case, the optical power density of the laser light reaching is about 1.4 kW / m 2 and the power received by the light receiving panel P1 is about 1.5 kW.

[0056] FIG. 8 is a diagram showing an example of the intensity distribution shape of the laser light from the optical concentrator 212B in the case of the configurations of FIGS. 6(a) and 6(b). FIG. 8(a) is a near-field pattern (NFP) image, and FIG. 8(b) is a far-field pattern (FFP) image. In the NFP image, the laser light having a substantially Gaussian shape output from each multimode fiber was arranged in a triangular lattice. On the other hand, in the FFP image, the laser lights overlapped appropriately, and an optical intensity distribution shape that spread in a regular hexagonal shape in the shape defined by the arrangement of the NFP image was obtained. Incidentally, if the laser light is assumed to be single mode, in the FFP image, the overlapping laser lights may interfere with each other, and irregular interference fringes may appear temporally and spatially. In contrast, in the case of FIG. 8, since the laser light is multimode and has low coherence, the generation of interference fringes is suppressed.

[0057] Each of the multimode fibers constituting the optical concentrator 212B has, for example, a core diameter of 50 μm, a beam parameter product BPP of 1.7 mm·mrad, and an M 2 value of 5.0. As another example, each of the multimode fibers may have a core diameter of 100 μm, a beam parameter product BPP of 3.3 mm·mrad, and an M 2 value of 9.7. Thus, multimode fibers having a core diameter of 50 to 100 μm, a BPP of 1 to 4 mm·mrad, and an M2 value of 10 or less can be used as the optical concentrator 212B. Incidentally, when the restrictions on output and projection distance are loose, other multimode fibers may be used.

[0058] [Still Another Configuration Example of the Laser Light Source] FIG. 9 is a diagram showing a configuration example of the laser light source. The laser light source 21C shown in FIG. 9(a) includes a laser device 211C including four fiber lasers, and further includes an optical concentrator 212C and four delivery fibers 213C. The optical concentrator 212C and the four delivery fibers 213C constitute an example of an adjustment mechanism.

[0059] The optical concentrator 212C is configured by bundling four multimode fibers corresponding to the number of fiber lasers and delivery fibers 213C included in the laser device 211C. Each multimode fiber is connected to each delivery fiber 213C. In the optical concentrator 212C, the four multimode fibers are arranged linearly. As a result, the light intensity distribution shape of the laser light output from the optical concentrator 212C to the projector 32C becomes a pseudo-linear shape.

[0060] According to the configuration of Fig. 9(a), when the projector 32C with the elevation angle and azimuth angle adjusted projects the laser light onto the light receiving panel P2 in which four unit panels in the shape of a square with one side of about 1 m are arranged linearly, the laser light is projected with a light intensity distribution shape that matches the shape of the light receiving panel P2, which is efficient and suitable. If the optical concentrator 212C is configured to be rotatable around its axis, the direction of the arrangement of the multimode fibers can be changed, so that suitable projection can be performed regardless of the direction of the arrangement of the unit panels of the light receiving panel P2.

[0061] The laser light source 21D shown in Fig. 9(b) includes a laser device 211D including 19 fiber lasers, and includes an optical concentrator 212D and 19 delivery fibers 213D that constitute an adjustment mechanism.

[0062] The optical concentrator 212D is configured by bundling 19 multimode fibers corresponding to the number of fiber lasers and delivery fibers 213D included in the laser device 211D. Each multimode fiber is connected to each delivery fiber 213D. In the optical concentrator 212D, the 19 multimode fibers are arranged in a triangular lattice shape, which is a closest packing structure. As a result, the light intensity distribution shape of the laser light output from the optical concentrator 212E to the projector 32E becomes a pseudo-regular hexagonal shape or a circular shape.

[0063] According to the configuration of FIG. 9(b), when a projector 32D with an adjusted elevation angle and azimuth angle projects laser light onto a light receiving panel P3 with a delivery length of about 5 m, in which 37 regular hexagonal unit panels are arranged in a triangular lattice, the laser light is projected with a light intensity distribution shape that matches the shape of the light receiving panel P3, which is thus efficient and suitable. If the optical concentrator 212D is configured to be rotatable about its axis, the direction of the arrangement of the multimode fibers can be changed, so that suitable projection can be performed regardless of the direction of the arrangement of the unit panels of the light receiving panel P3.

[0064] The laser light source 21E shown in FIG. 9(c) includes a laser device 211E containing 16 fiber lasers, and an optical concentrator 212E and 16 delivery fibers 213E that constitute an adjustment mechanism.

[0065] The optical concentrator 212E is configured by bundling 16 multimode fibers corresponding to the number of fiber lasers and delivery fibers 213E included in the laser device 211E. Each multimode fiber is connected to each delivery fiber 213E. In the optical concentrator 212E, the 16 multimode fibers are arranged in a square shape. As a result, the light intensity distribution shape of the laser light output from the optical concentrator 212E to the projector 32E becomes a pseudo-square shape.

[0066] According to the configuration of FIG. 9(c), when a projector 32E with an adjusted elevation angle and azimuth angle projects laser light onto a light receiving panel P4 with a side length of about 4 m, in which 16 unit panels with a side length of about 1 m are arranged in a square shape, the laser light is projected with a light intensity distribution shape that matches the shape of the light receiving panel P4, which is thus efficient and suitable. If the optical concentrator 212E is configured to be rotatable about its axis, the direction of the arrangement of the multimode fibers can be changed, so that suitable projection can be performed regardless of the direction of the arrangement of the unit panels of the light receiving panel P4.

[0067] Note that, as shown in Fig. 9(a), when the laser light is projected from the projector 32C toward the light receiving panel 20 km away, the laser light is attenuated by scattering due to the atmosphere, clouds, rain, dust (hereinafter referred to as the atmosphere, etc.). At this time, if the beam diameter is increased in the region passing through the atmosphere, etc., like the region surrounded by the broken line, it becomes relatively difficult to be scattered by the atmosphere, etc., so the attenuation amount can be made relatively small. The same applies to the cases of Figs. 9(b) and 9(c).

[0068] [Another Example of Projector] Fig. 10 is a diagram showing an example of a projector. The projector 32F shown in Fig. 10 is optically connected to a delivery fiber 213F arranged in a triangular lattice and an optical concentrator 212F formed by arranging multi-core fibers in a triangular lattice. The delivery fiber 213F and the optical concentrator 212F constitute an example of an adjustment mechanism.

[0069] The projector 32F includes a mirror group 32Fa having two mirrors, a sub-mirror 32Fb, a main lens 32Fc, and a camera 32Fd. The camera 32Fd is connected to the monitor M.

[0070] When the laser light is input from the delivery fiber 213F to the projector 32F via the optical concentrator 212F, the mirror group 32Fa reflects the laser light toward the sub-mirror 32Fb. The sub-mirror 32Fb reflects the laser light toward the main lens 32Fc. The main lens 32Fc collimates the laser light as an objective lens and projects it toward the light receiving panel P1.

[0071] When the combined focal length of the combination of the main lens 32Fc and the sub-mirror 32Fb is 3000 mm and the transfer length between the laser lights in the optical concentrator 212F is 250 μm, the laser light has a diameter of about 282 mm at the beam waist. By adjusting the position of the main lens 32Fc, even at the position of the light receiving panel hundreds of meters away, the diameter of the beam B2 of the laser light can be adjusted in the range of several tens of centimeters to several meters.

[0072] Here, the two mirrors of the mirror group 32Fa can adjust their relative positions and relative angles or be rotated. Also, the main lens 32Fc can be translated parallel to the optical axis like a zoom lens to change the combined focal length of the combination with the sub-mirror 32Fb. As a result, the laser beam B2 can be deformed like the beam B3, or the divergence angle or propagation direction of the laser beam can be adjusted. The mirror group 32Fa and the main lens 32Fc are examples of adjustment mechanisms. As a result, even if the attitude of the flying object F1 (see Fig. 1) equipped with the light receiving panel P1 changes and the shape seen from the projector 32F of the light receiving panel P1 changes, the shape of the beam B2 can be deformed like the beam B3 to follow. Thereby, efficient power supply can be maintained even if the attitude of the flying object F1 changes.

[0073] In addition, the main lens 32Fc can form an image of the shape of the laser beam on the camera 32Fd. Thereby, the image of the shape of the laser beam is projected onto the monitor M. Therefore, the deformation of the beam can be adjusted by checking the monitor M. The camera 32Fd and the monitor M are examples of a light receiving state detector that detects the light receiving state of the light receiving body. Note that the adjustment mechanism constituted by the mirror group 32Fa and the main lens 32Fc may be configured to automatically adjust based on the light receiving state detected by the light receiving state detector.

[0074] Fig. 11 is a diagram showing an example of a projector. The projector 32G shown in Fig. 11(a) is attached to a light concentrator 212G including six multi-mode fibers 212Ga connected to six laser devices via delivery fibers. The multi-mode fibers 212Ga are each inserted into a cylindrical cover 212Gb.

[0075] The light projector 32G includes a cylindrical portion 32Ga in which the tip side of the multimode fiber 212Ga is located inside, and a cover glass 32Gb disposed on the objective side of the cylindrical portion 32Ga. Further, the light projector 32G includes a collimating lens 32Gc provided at the tip of each multimode fiber 212Ga. Further, the light projector 32G includes an angle adjustment screw 32Gd that supports the multimode fiber 212Ga and performs angle adjustment with respect to the cylindrical portion 32Ga. A flexible member is sandwiched between the covers 212Gb and between the cover 212Gb and the angle adjustment screw 32Gd so that the light concentrator 212G can be angle-adjusted with respect to the cylindrical portion 32Ga. The angle adjustment screw 32Gd is an example of a component of the adjustment mechanism.

[0076] In the light projector 32G, the angle adjustment screw 32Gd can deform the arrangement of the multimode fibers 212Ga from the state shown in FIG. 11(b) to the state shown in FIG. 11(c), for example. Thereby, even if the shape of the light receiving panel P1 as seen from the light projector 32G changes, it can be made to follow by deforming the shape of the laser beam. Thereby, efficient power supply can be maintained.

[0077] [Another configuration example of the laser light source] FIG. 12 is a diagram showing a configuration example of the laser light source. As shown in FIG. 12(a), the laser light source 211H includes laser diodes 211Ha which are a plurality of laser devices, a light concentrator 211Hb, and a delivery fiber 213Hc. A laser light source such as the laser light source 211H is called a fiber output laser diode, a direct diode laser (DDL), or the like.

[0078] The laser diode 211Ha outputs laser light with a wavelength of, for example, 915 nm. The optical concentrator 211Hb aggregates the laser light output from each of the plurality of laser diodes 211Ha and inputs it to the delivery fiber 213Hc. The optical concentrator 212 is, for example, an integrated bundle of a plurality of fibers, and is tapered thinly in the emission direction like a TFB in order to adjust the size of the BPP (Beam Parameter Products) of the output light. As the optical concentrator, those that are not tapered or tapered to be thicker in the emission direction can also be used.

[0079] The delivery fiber 213Hc is a multimode fiber that propagates the laser light to the projector. The delivery fiber 213Hc has a core diameter of, for example, 300 μm and a numerical aperture (NA) of, for example, 0.22. At this time, since the laser light propagates in a large number of propagation modes in the delivery fiber 213Hc, the light intensity distribution shape of the laser light output from the delivery fiber 213Hc becomes a flat top shape as shown in Fig. 12(b). Also, the M 2 value of the laser light at this time is, for example, 66 to 113.

[0080] The laser light source 211H has a relatively low condensing property because of its large M 2 value. Therefore, it is suitable for optical power feeding over a distance of about several hundred meters to 1 km.

[0081] Fig. 13 is a diagram showing a configuration example of a laser light source. The laser light source 21I shown in Fig. 13(a) includes a laser device 211I including four DDLs like the laser light source 211H, and includes an optical concentrator 212I and four delivery fibers 213I that constitute an example of an adjustment mechanism.

[0082] The optical concentrator 212I is configured by bundling four multimode fibers corresponding to the number of DDLs and delivery fibers 213I included in the laser device 211I. Each multimode fiber is connected to each delivery fiber 213I. In the optical concentrator 212I, the four multimode fibers are arranged in a square shape. As a result, the light intensity distribution shape of the laser light output from the optical concentrator 212I to the projector 32I becomes a pseudo-square shape.

[0083] According to the configuration of Fig. 13(a), when the projector 32I with adjusted elevation and azimuth angles projects laser light onto the light receiving panel P5 with a side length of about 1 m, which is composed of four unit panels in a square shape with a side length of about 30 m arranged in a square shape, the laser light is projected with a light intensity distribution shape that matches the shape of the light receiving panel P5, which is efficient and suitable. The distance from the projector 32I to the light receiving panel P5 is, for example, 0.8 km. If the optical concentrator 212I is configured to be rotatable around an axis, the direction of the arrangement of the multimode fibers can be changed, so that suitable projection can be performed regardless of the direction of the arrangement of the unit panels of the light receiving panel P5.

[0084] The laser light source 21J shown in Fig. 13(b) includes a laser device 211J including one DDL and one delivery fiber 213J that constitutes an example of an adjustment mechanism.

[0085] According to the configuration of Fig. 13(b), when the projector 32J with adjusted elevation and azimuth angles projects laser light onto the light receiving panel P6 with a span length of about 5 m, which is mounted on the flying object F2 (a drone) and composed of 37 unit panels in a regular hexagon arranged in a triangular lattice, the laser light is projected with a light intensity distribution shape that matches the shape of the light receiving panel P6, which is efficient and suitable.

[0086] As shown in Fig. 13(a), when projecting laser light from the laser light source 21C toward a light receiving panel 0.8 km away, the amount of attenuation of the laser light due to scattering by the atmosphere or the like is relatively small. The same applies to the case of Fig. 13(b).

[0087] [Configuration Example Using LRNB] FIG. 14 is a diagram showing a configuration example using a Long Range Nondiffractiog Beam (LRNB). The LRNB is a beam that propagates over a long distance while maintaining a narrow beam diameter (for example, Y. Suzuki et al., "Atmospheric Propagation Experiment of Long Range Nondiffractiog Beam Using a Large Aperture Phase Plate", Proceedings of the 25th Laser Sensing Symposium, pp. 157 - 158, 2007.).

[0088] The laser light source 21K includes a laser device 211K including a fiber laser or DDL, a single delivery fiber 213K, and a phase plate 215K. The laser device 211K outputs laser light having a wavelength of, for example, 1050 nm, an M 2 value of, for example, 1.05, and a power of, for example, several kW.

[0089] The phase plate 215K converts the laser light input from the laser device 211K via the delivery fiber 213K into a beam B4 which is an LRNB. The projector 32K projects the beam B4 onto a circular light receiving panel P1 with a diameter of about 50 cm located 20 km away. Since the beam B4 which is an LRNB has a region with relatively high power concentrated in the central part, it is preferable to project the beam so that this high - power region hits the light receiving panel P1.

[0090] [Power Feeding Performance] Here, as laser devices, the power feeding performance was calculated when a single - mode fiber laser (hereinafter abbreviated as SM - FL) that outputs single - mode laser light such as the fiber laser 211, a multi - mode fiber laser (hereinafter abbreviated as MM - FL) such as the laser device 211B, and a DDL are projected and power - fed to a distant place by a collimating lens optical system.

[0091] In the SM - FL, with a laser light wavelength of 1050 nm and a power of 1 kW, the core diameter of the single - mode fiber that outputs the laser light to the collimating lens optical system is 16 μm, the divergence angle is 47 mrad, M 2The value was set to 1.1, the focal length of the collimating lens optical system was set to 3000 mm, and the radius of the collimating lens was set to 141 mm. As a result, with the reach distance of the laser beam being 20 km, the focusing radius was 135 mm, the reach power was 0.5 kW, and the maximum optical power density was 38 kW / m 2 and the light-receiving area where the optical power density was 1 kW / m 2 or more was 0.5 m 2 .

[0092] In MM-FL, with the wavelength of the laser beam being 1050 nm and the power being 6 kW, the core diameter of the multimode fiber that outputs the laser beam to the collimating lens optical system was 48 μm, the divergence angle was 65 mrad, and the M 2 value was set to 4.5, the focal length of the collimating lens optical system was set to 3500 mm, and the lens radius was set to 228 mm. As a result, with the reach distance of the laser beam being 20 km, the focusing radius was 260 mm, the reach power was 3.3 kW, and the maximum optical power density was 62 kW / m 2 and the light-receiving area where the optical power density was 1 kW / m 2 or more was 3.3 m 2 .

[0093] In DDL, with the wavelength of the laser beam being 915 nm and the power being 1 kW, the core diameter of the multimode fiber that outputs the laser beam to the collimating lens optical system was 300 μm, the divergence angle was 220 mrad, and the M 2 value was set to 113, the focal length of the collimating lens optical system was set to 1000 mm, and the lens radius was set to 224 mm. As a result, with the reach distance of the laser beam being 0.8 km, the focusing radius was 311 mm, the reach power was 0.9 kW, and the maximum optical power density was 12 kW / m 2 and the light-receiving area where the optical power density was 1 kW / m 2 or more was 0.9 m 2 .

[0094] In MM-FL, since power of 6 to 18 kW can be obtained without significantly degrading the beam quality, the light-receiving area where the optical power density is 1 kW / m 2 or more is 3.3 to 10 m 2 and electric power of 0.5 to 1.5 kW can be obtained.

[0095] The DDL is M 2 Although the value is large and the beam quality is poor, it is attractive for applications to small power supplies for distances of, for example, several hundred meters because it has a low cost and a high power-to-light conversion efficiency compared to fiber lasers. Also, if the output fiber of the DDL is further bundled, more power can be supplied.

[0096] [Configuration Example of Light-Receiving Panel] FIG. 15 is a diagram showing a configuration example of a light-receiving panel. As shown in FIG. 15(a), the light-receiving panel P7 onto which laser light is projected is rectangular and is provided on the wing portion of the flying object F3. Further, as shown in FIG. 15(b), the light-receiving panel P7 is attached to the back surface of the wing portion, that is, the ground side, and a solar panel P8 for receiving sunlight is provided on the front surface of the wing portion, that is, the sky side. Thereby, when the flying object F3 is in a situation where it can receive sunlight, it can use sunlight as a power source and is also likely to receive power supply by the projection of laser light from the ground.

[0097] Also, as in the flying object F3A shown in FIG. 15(c), a transmission window F3Aa that transmits laser light such as glass is provided on the ground side of the wing portion, and the solar panel P8 may be configured to receive sunlight on the front surface and receive the laser light transmitted through the transmission window F3Aa on the back surface. Thereby, the number of light-receiving panels mounted on the flying object F3A can be reduced.

[0098] Further, like the flying object F3B shown in FIG. 15(d), a transmission window F3Ba and reflection mirrors F3Bb and F3Bc may be provided on the wing portion. The transmission window F3Ba is made of glass or the like, is provided on the ground side of the wing portion, and transmits laser light. The reflection mirror F3Bb is a concave mirror provided at the wing tip, and reflects the laser light transmitted through the transmission window F3Ba while condensing it. The reflection mirror F3Bb is an example of an optical element that changes the propagation direction of the laser light. The reflection mirror F3Bc reflects the laser light reflected by the reflection mirror F3Bb toward the back surface of the solar panel P8. Part of the laser light that reaches the solar panel P8 is absorbed and photoelectrically converted, but the rest is reflected and reaches the reflection mirror F3Bc again, and is further reflected toward the back surface of the solar panel P8. The laser light is effectively absorbed by the solar panel P8 and photoelectrically converted by being repeatedly reflected by the reflection mirror F3Bc toward the back surface of the solar panel P8 when the remaining light that is not absorbed is reflected. The solar panel P8 is an example of a light receiver that receives the laser light whose propagation direction has been changed and sunlight and performs photoelectric conversion.

[0099] FIG. 16 is a diagram showing another configuration example of the light receiving panel. The flying object F4 shown in FIG. 16 includes a wing portion F4a and a fuselage portion F4b. A transmission window F4c, a reflection mirror F4d, a cover F4e, and two light receiving panels P9a and P9b are provided on the wing portion F4a. Also, a battery F4f is mounted on the fuselage portion F4b.

[0100] The transmission window F4c is made of glass or the like, is provided on the ground side of the wing portion F4a, and transmits the laser light. The reflection mirror F4d is a concave mirror, and reflects the laser light transmitted through the transmission window F4c while condensing it. The cover F4e has a reflection and transmission characteristic such that a surface treatment that transmits most of the wavelength components contained in sunlight is applied, and a back surface treatment that reflects the laser light reflected by the reflection mirror F4d toward the surface of the light receiving panel P9a is applied. Note that the surfaces of the light receiving panels P9a and P9b are subjected to uneven processing to enhance the absorption efficiency. The laser light that reaches the light receiving panel P9a is partially absorbed and photoelectrically converted, but the rest is reflected and reaches the back surface of the cover F4e, and is further reflected toward the surfaces of the light receiving panels P9a and P9b. The remaining laser light that is not absorbed in this way is repeatedly reflected by the cover F4e toward the surface of the light receiving panel P9a, and is effectively absorbed by the light receiving panel P9a and photoelectrically converted.

[0101] The light receiving panels P9a and P9b are connected in parallel to the battery F4f and can be electrically disconnected from each other by a switch. Thereby, when power supply by laser light is performed, if the light receiving panel P9b that does not receive the laser light is disconnected, a decrease in power generation efficiency can be suppressed.

[0102] In addition, in the flying objects of FIGS. 15 and 16, a diffusion plate for diffusing the laser light may be provided on the wing portion, and the laser light may be diffused and then input to the solar panel or the light receiving panel.

[0103] [Configuration example for detecting obstacles] FIG. 17 is a diagram showing a configuration example for detecting an obstacle. The projector 32 (see FIG. 1) projects a laser beam with a power of several kW output from the laser light source 21 of the laser unit 2 as a beam B5 with a beam diameter of 1 m to several meters toward the light receiving panel P1 provided in the flying object F1. The flying object F1 is provided with light receiving elements D1 and D2. The light receiving elements D1 and D2 receive a part of the beam B6 and detect the amount of light received by the light receiving panel P1. The transmitter T provided in the flying object F1 transmits a wireless communication signal including information on the detection results of the light receiving elements D1 and D2 to the communicator 5. The communicator 5 transmits the information included in the received communication signal to the power supply device 22. When the power supply device 22 determines based on the information that the amount of light received by the light receiving panel is equal to or less than a threshold value, it stops the output of the laser light by the laser unit 2. The light receiving elements D1 and D2 are an example of an obstacle detector that detects an obstacle between the light receiver and the laser light source, and are an example of an obstacle detector that detects an obstacle within the range of the beam of the projected laser light. Further, the power supply device 22 is an example of a control unit that stops or resumes the output of the laser light based on the detection result of the obstacle detector.

[0104] Also, the camera C images the light receiving panel P1, and the monitor M displays the image imaged by the camera C. Here, when an obstacle enters the path of the beam B5, the obstacle reflects a part of the beam B5, so scattered light or a bright spot is imaged. When an obstacle enters the path of the beam B5, the camera C may detect the intrusion and display information notifying the intrusion on the monitor M. In this case, the camera C transmits information on the intrusion of the obstacle to the power supply device 22. The power supply device 22 stops the output of the laser light based on the intrusion information. Then, when the obstacle disappears from the path of the beam B5, the output of the laser light is resumed. The camera C is an example of an obstacle detector that detects an obstacle within a predetermined range including the beam of the projected laser light.

[0105] Obstacles such as the flying object F5 like a bird or a building exist at an altitude of, for example, several hundred meters, and a flying object F6 such as an airliner exists at an altitude of, for example, about 10 km. Since the speed of an airliner is, for example, 278 m / s, it is desirable to stop the output of the laser light within several milliseconds from the detection of the intrusion of the obstacle.

[0106] Also, a plurality of guide laser devices GL may be arranged to surround the beam B5 to form a tubular beam B6, and a camera C may image whether an obstacle has intruded into the path of the beam B6. The guide laser device GL includes, for example, a laser light source with a safety class of Class 1. The guide laser device GL and the camera C are an example of an obstacle detector that detects obstacles within a predetermined range including the beam of the projected laser light.

[0107] [Usage Modes of the Optical Power Supply System] FIG. 18 is a diagram showing an example of a usage mode of the optical power supply system 1. As shown in FIG. 18, the aircraft F1 normally receives optical power supply from the laser irradiation base BS, but the power supply amount may be insufficient depending on weather conditions such as the presence of clouds. In this case, since the optical power supply system 1 can be moved to any location, it can move to a location with good optical power supply conditions such as no clouds and supply power to the aircraft F1.

[0108] In particular, fiber lasers and DDLs are small and lightweight lasers compared to solid-state lasers and gas lasers, etc., and are less affected by the influence of optical axis deviation due to vibration, thus preferably satisfying the requirement for movement.

[0109] FIG. 19 is a diagram showing an example of a usage mode of the optical power supply system 1. As shown in FIG. 19, a floating aircraft F5 such as a flying ship includes a solar panel P10 and a light receiving panel P11 for power supply by laser light. Also, the aircraft F5 includes a communication device C1 having a wireless communication relay function. The power consumption of the communication device C1 is, for example, 100 W. Further, the aircraft F5 includes, for example, a position control motor with a power consumption of 100 W.

[0110] Such a flying object F5 is used to emergently secure a communication area by the communication device C1 in a disaster-stricken area where communication means have been lost. During the day, the flying object F5 is powered by the solar panel P10. The solar panel P10 includes, for example, five unit panels with a maximum power generation of 200 W each and has a maximum power generation capacity of 1000 W. Also, at night, the flying object F5 can receive optical power supply from the optical power supply system 1 moved to, for example, the middle of the mountain MO via the light receiving panel P11. The light receiving panel P11 is, for example, circular with a diameter of 2 m and can receive about 250 W of optical power supply when the optical power supply system 1 located 20 km away projects a laser beam with a power of 6 kW. As a result, it becomes possible to operate to secure a communication area in the disaster-stricken area day and night.

[0111] FIG. 20 is a diagram showing an example of the usage mode of the optical power supply system 1. As shown in FIG. 20, when a disaster such as a landslide S occurs in the mountain MO and the settlements in the mountainous area are isolated, a base station system G and a light receiving panel P12 are transported by a helicopter or a drone. Then, the light receiving panel P12 is supplied with optical power by the optical power supply system 1 located several kilometers or more away, and the base station system G is operated. Thereby, it is possible to emergently and immediately secure a communication area for the settlements that have lost communication means due to the disaster.

[0112] Note that the present invention is not limited by the above-described embodiment. Those configured by appropriately combining the above-described components are also included in the present invention. Further, additional effects and modification examples can be easily derived by those skilled in the art. Therefore, a broader aspect of the present invention is not limited to the above-described embodiment, and various changes are possible.

Explanation of Reference Numerals

[0113] 1: Optical power supply system 2: Laser unit 3: Light projection unit 4: Sensor 5: Communicator 6: Vehicle 7: Vibration isolation and shock isolation device 21, 21B, 21C, 21D, 21E, 21I, 21J, 21K, 211H: Laser light source 22: Power supply device 23: Battery 24: Chirp 31: Tracking device 32, 32B, 32C, 32D, 32E, 32F, 32G, 32I, 32J, 32K: Light projector 32a, 32Ba: Collimating lens optical system 32Fa: Mirror group 32Fb: Sub-mirror 32Fc: Main lens 32Fd, C: Camera 32Ga: Cylindrical part 32Gb: Cover glass 32Gc: Collimating lens 32Gd: Angle adjustment screw 211: Fiber laser 211a, 211b: Excitation light source 211c, 211d, 211Bb, 211Hb, 212, 212B, 212BA, 212C, 212D, 212E, 212F, 212G, 212I: Optical concentrator 211e, 211f: TFB 211g: Optical amplification fiber 211B, 211C, 211D, 211E, 211I, 211J, 211K: Laser device 211Ba: Output fiber 211Ha: Laser diode 212Ga: Multi-mode fiber 212Gb: Cover 213, 213A, 213B, 213C, 213D, 213E, 213F, 213Hc, 213I, 213J, 213K: Delivery fiber 215K: Phase plate B1, B2, B3, B4, B5, B6: Beam BP1, BP2, BP3, BP4, BP5, BP6: Light intensity distribution shape BS: Laser irradiation base C1: Communication device D1, D2: Light-receiving elements F1, F2, F3, F3A, F3B, F4, F5, F6: Flying objects F3Aa, F3Ba, F4c: Transparent windows F3Bb, F3Bc, F4d: Reflective mirrors F4a: Wing parts F4b: Body parts F4e: Covers F4f: Batteries G: Base station system GL: Guide laser device M: Monitor MO: Mountains P1, P2, P3, P4, P5, P6, P7, P9a, P9b, P11, P12: Light-receiving panels P8, P10: Solar panels T: Transmitter

Claims

1. A laser light source having a plurality of laser devices, and aggregating and outputting a plurality of laser lights output from the plurality of laser devices; A projector that projects the laser light output from the laser light source toward a light receiver located remotely and performing photoelectric conversion; An adjustment mechanism for adjusting the light intensity distribution of the laser light projected onto the light receiver; Comprising: The adjustment mechanism includes a delivery fiber that propagates laser light from the laser light source to the projector, a light aggregator that inputs the laser light output from each of the plurality of laser devices into the delivery fiber, and a plurality of output optical fibers that propagate each of the laser lights output from the plurality of laser devices; The plurality of output optical fibers are arranged in a shape that matches the shape of the light receiver A photovoltaic power supply system.

2. A laser light source comprising a fiber laser or a fiber output laser diode; A projector that projects the laser light output from the laser light source toward a light receiver located remotely and performing photoelectric conversion; An adjustment mechanism for adjusting the light intensity distribution of the laser light projected onto the light receiver; Comprising: The laser light source has a plurality of laser devices; The adjustment mechanism includes a plurality of output optical fibers that propagate each of the laser lights output from the plurality of laser devices; The plurality of output optical fibers are arranged in a shape that matches the shape of the light receiver A photovoltaic power supply system.

3. A laser light source; A projector that projects the laser light output from the laser light source toward a light receiver located remotely and performing photoelectric conversion; An adjustment mechanism for adjusting the light intensity distribution of the laser light projected onto the light receiver; A moving body on which the laser light source is mounted; Comprising: The laser light source has a plurality of laser devices; The adjustment mechanism includes a plurality of output optical fibers that propagate each of the laser lights output from the plurality of laser devices; The plurality of output optical fibers are arranged in a shape that matches the shape of the light receiver A photovoltaic power supply system.

4. The light aggregator is configured by bundling and integrating a plurality of fibers, and The adjustment mechanism adjusts the light intensity distribution of the laser light so that the shape of the light intensity distribution of the projected laser light is a flat top shape The photovoltaic power supply system according to claim 1.

5. An obstacle detector that detects an obstacle between the light receiver and the laser light source; A control unit that stops or starts the output of the laser light based on the detection result of the obstacle detector; Comprising The optical power supply system according to any one of claims 1 to 3.

6. The obstacle detector detects an obstacle within a predetermined range including the beam of the laser light to be projected. The optical power supply system according to claim 5.

7. The obstacle detector detects an obstacle within the range of the beam of the laser light to be projected. The optical power supply system according to claim 5.

Images