Communication device and communication system

Abstract

The present invention improves tracking performance and suppresses the degradation of communication quality and communication speed in optical wireless communication. A communication device (1) comprises: a main mirror part (10); a base part (30); and one or multiple hollow shafts (41, 42) that rotatably connect the main mirror part to the base part, wherein an optical path (LP) that passes through the one or multiple hollow shafts is formed, said optical path being a laser beam optical path for communication from the main mirror part to the base part.

Description

Communication device and communication system

[0001] The present disclosure relates to a communication device that performs optical wireless communication, and a communication system.

[0002] Optical wireless communication technology for performing communication by propagating highly directional light into vacuum or atmosphere via flying objects, artificial satellites, or the like has been developed (for example, Patent Document 1).

[0003] Japanese Patent No. 7642160

[0004] A communication device according to an aspect of the present disclosure includes a primary mirror portion, a base portion, and one or a plurality of hollow shafts that pivotably connect the primary mirror portion to the base portion, wherein an optical path for communication laser light from the primary mirror portion to the base portion that penetrates the one or plurality of hollow shafts is formed.

[0005] A communication system according to an aspect of the present disclosure is a communication system including a plurality of communication devices, wherein at least any one of the plurality of communication devices includes a primary mirror portion, a base portion, and one or a plurality of hollow shafts that pivotably connect the primary mirror portion to the base portion, wherein an optical path for communication laser light from the primary mirror portion to the base portion that penetrates the one or plurality of hollow shafts is formed.

[0006] These are schematic cross-sectional views of a communication device according to an embodiment, a schematic front view of the communication device according to an embodiment, a block diagram schematically showing the configuration of the communication device according to an embodiment, a perspective view of the communication device according to an embodiment, a front view of the communication device according to an embodiment, a right side view of the communication device according to an embodiment, a back view of the communication device according to an embodiment, a top view of the communication device according to an embodiment, and a diagram showing a configuration example of a communication system according to an embodiment.

[0007] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. For ease of understanding, the background and problems of the present disclosure will be described first, and then the details of the present disclosure will be described.

[0008] <Background and Challenges> Optical wireless communication technology is known for transmitting highly directional light through a vacuum or atmosphere via flying objects or artificial satellites. In optical wireless communication, optical wireless communication devices that receive light from or transmit light to a moving communication partner, such as a flying object, require a tracking mechanism to track the communication partner. As an example of such a tracking mechanism, a gimbal system is often employed in which the main mirror is supported and driven by multiple drive axes.

[0009] Here, as an example of the gimbal system, one can consider a method in which the primary mirror and collimator are mounted on the primary mirror unit, and the collimated light is transmitted to the subsequent modem via optical fiber. In this method, a rotating connector for optical fiber is required to pass through the drive shaft, but this connector causes optical loss, which leads to a problem of reduced communication quality.

[0010] Another example of a gimbal system involves mounting the primary mirror, collimator, and modem on the primary mirror unit, and transmitting the communication data converted by the modem to the downstream unit via cable. This system requires a rotating connector for the cable to pass through the drive axis, but this connector has the problem of limiting the communication speed. Also, since the modem is mounted on the primary mirror unit, the moment of inertia of the primary mirror unit becomes large, which can interfere with the tracking function.

[0011] One aspect of this disclosure aims to provide a technology that can suppress a decrease in communication quality and communication speed, as well as improve tracking performance, in optical wireless communication.

[0012] <Overview of Communication Device 1> The communication device 1 according to this embodiment is, for example, an optical wireless communication device that communicates by propagating a communication laser beam in a vacuum or atmosphere via a flying object or artificial satellite. As described below, the communication device 1 comprises: - A main mirror section and a base section, and - One or more hollow shafts that rotatably connect the main mirror section to the base section, and the communication device 1 has: - An optical path for the communication laser beam from the main mirror section to the base section, which penetrates the one or more hollow shafts.

[0013] As described above, in the communication device 1 according to this embodiment, since an optical path for communication laser light is formed from the main mirror to the base, passing through one or more hollow axes, the communication laser light can be guided to the base without passing through either the rotating connector for optical fiber or the rotating connector for cable. For this reason, with the above configuration, there is no need to place a collimator and a modem in the main mirror, so the moment of inertia of the main mirror can be reduced compared to a configuration in which a collimator or modem is placed in the main mirror. This improves tracking performance. Furthermore, with the above configuration, since the communication laser light does not pass through either the rotating connector for optical fiber or the rotating connector for cable, a decrease in communication quality and communication speed can be suppressed.

[0014] (Configuration of Communication Device 1) The configuration of communication device 1 will be explained with reference to Figures 1 to 3. Figure 1 is a schematic cross-sectional view of communication device 1, and Figure 2 is a schematic front view of communication device 1. For the sake of explanation, in Figures 1 and 2, a coordinate system is set up so that the right side of the x-axis in the horizontal direction is positive, the far side of the horizontal plane of the paper is positive, and the upward side of the vertical plane is positive.

[0015] As shown in Figure 2, the communication device 1 comprises a main mirror section 10, a support section 20, and a base section 30. Also as shown in Figure 2, the communication device 1 includes: a first hollow shaft 41 that connects the main mirror section 10 to the support section 20 so as to be rotatable around the x-axis (first axis), and a second hollow shaft 42 that connects the support section 20 to the base section 30 so as to be rotatable around the z-axis (second axis), which is not parallel to the x-axis (first axis). Here, the x-axis and the z-axis perpendicular to the x-axis are given as examples of the first and second axes, respectively, but this does not limit this embodiment, and the first and second axes only need to be non-parallel. Furthermore, the number of hollow shafts provided in the communication device 1 is not limited to the above example, and may be one or three or more.

[0016] (Main mirror section 10) As shown in Figure 2, the main mirror section 10 is equipped with a light-receiving window 11 on its front side. Here, the term "light-receiving window 11" is not limited to this embodiment and may also be called a light-transmitting window, light-transmitting window, etc. The light-receiving window 11 is not particularly limited as long as it transmits the communication laser light transmitted and received by the communication device 1. In addition, the light-receiving window 11 may also function as a lens that refracts the communication laser light.

[0017] Figure 1 is a cross-sectional view obtained by cutting the communication device 1 through a cross-section including the optical path LP of the communication laser light in the communication device 1. As shown in Figure 1, the main mirror section 10 includes a main mirror M11 and a secondary mirror M12. The main mirror M11 is a concave mirror as an example, and the secondary mirror M12 is a convex mirror as an example, but is not limited to these. For convenience, the following description will be given in accordance with the propagation order of the laser light when the communication device 1 receives the communication laser light, but this is not limited to this embodiment. More specifically, as will be described later, the communication device 1 also functions as a device that transmits (sends out) the communication laser light.

[0018] The communication laser light incident on the primary mirror section 10 from the front side (the near side of the paper in Figure 2, the negative side of the y-axis) is reflected by the primary mirror M11, which is located on the back side of the primary mirror section 10 and has its mirror surface facing the front side, and is focused by the secondary mirror M12, which is located in front of the primary mirror M11. For example, the mirror surface of the secondary mirror M12 is oriented such that the normal vector of the mirror surface points at 45° from the positive side of the x-axis on the xy-plane (so that the normal vector of the mirror surface on the xy-plane is (1,1)). As a result, the communication laser light incident on the secondary mirror M12 from the primary mirror M11 is guided toward the positive side of the x-axis in Figure 2.

[0019] In Figure 1, the communication laser beam emitted from the secondary mirror M12 is denoted by the symbol LP. The communication laser beam LP is sometimes simply referred to as the laser beam LP. Furthermore, the upper end (the end with a larger z-coordinate) of the communication laser beam LP in the primary mirror 10 is denoted by the symbol L1, and the lower end (the end with a smaller z-coordinate) of the communication laser beam LP in the primary mirror 10 is denoted by the symbol L2. Unless otherwise specified, the same symbol LP is sometimes used to refer to the optical path through which the communication laser beam LP propagates within the communication device 1, and it is sometimes referred to as the optical path LP. Therefore, symbols L1 and L2 can also be considered as symbols that define the ends (edges) of the optical path LP.

[0020] (First Hollow Axis 41) The first hollow axis 41 connects the main mirror 10 to the support 20 so that it can rotate around the x-axis (first axis). As shown in Figure 1, the communication laser beam LP directed by the secondary mirror M12 penetrates the hollow portion 41v formed in the first hollow axis 41. Here, as shown in Figure 1, the hollow portion 41v is a hollow region defined by the inner wall 41a of the first hollow axis 41. As an example, when the communication device 1 is located on the Earth's surface or in the atmosphere, the hollow portion 41v is filled with air or with gas filled inside the communication device 1. As another example, when the communication device 1 is located in outer space, the hollow portion 41v is a vacuum or filled with gas filled inside the communication device 1. However, these examples do not limit this embodiment.

[0021] The specific configuration of the first hollow shaft 41 is not limited to this embodiment, but as an example, it can be configured to include a bearing and a shaft that is rotatably supported by the bearing and has the hollow portion 41v formed on it. In this configuration, the hollow portion 41v is defined by an inner wall 41a formed to penetrate the shaft.

[0022] Furthermore, the first hollow shaft 41 is equipped with a drive motor for rotating the main mirror section 10 relative to the support section 20. In other words, it is equipped with a drive motor for driving the first hollow shaft 41. Here, this drive motor is controlled, for example, by a receiving section 31 or a transmitting section 32, which will be described later.

[0023] (Support section 20) The support section 20 supports the main mirror section 10 relative to the base section 30. The designation of the support section 20 is not limited to this embodiment, and it may also be called a support frame or gimbal frame.

[0024] As shown in Figure 1, for example, the support portion 20 has a cavity formed inside, and the laser light LP is guided through this cavity. Here, as shown in Figure 1, the support portion 20 is equipped with a plurality of mirrors M21, M22, and M23 for directing the communication laser light LP. For example, mirror M21 is oriented to guide the laser light LP incident from the secondary mirror M12 of the main mirror portion 10 along the x-axis to the negative side in the z-axis direction. Similarly, mirror M22 is oriented to guide the laser light LP incident from mirror M21 along the z-axis to the negative side in the x-axis direction. Similarly, mirror M23 is oriented to guide the laser light LP incident from mirror M22 along the x-axis to the negative side in the z-axis direction.

[0025] Furthermore, when the communication device 1 is placed on the Earth's surface or in the atmosphere, the cavity in the support portion 20 through which the laser beam LP is guided is filled with air or with a gas filled inside the communication device 1. As another example, when the communication device 1 is placed in outer space, the cavity is either a vacuum or filled with a gas filled inside the communication device 1. However, these examples do not limit this embodiment.

[0026] In the above example, the case in which the cavity through which the laser light LP is guided is formed inside the support portion 20 was described, but this is not limited to this embodiment. As will be described later, the support portion 20 may be configured to separately include a frame portion that supports the main mirror portion 10 with respect to the base portion 30, and a housing for shielding the optical path of the communication laser light LP from the outside world.

[0027] (Second Hollow Axis 42) The second hollow axis 42 connects the support portion 20 to the base portion 30 so as to be rotatable around the z-axis (second axis). As shown in Figure 1, the communication laser beam LP, directed by the mirror M23 of the support portion 20, penetrates the hollow portion 42v formed in the second hollow axis 42. Here, as shown in Figure 1, the hollow portion 42v is a hollow region defined by the inner wall 42a of the second hollow axis 42. As an example, when the communication device 1 is located on the Earth's surface or in the atmosphere, the hollow portion 42v is filled with air or with gas filled inside the communication device 1. As another example, when the communication device 1 is located in outer space, the hollow portion 42v is a vacuum or filled with gas filled inside the communication device 1. However, these examples do not limit this embodiment.

[0028] The specific configuration of the second hollow shaft 42 is not limited to this embodiment, but as an example, it can be configured to include a bearing and a shaft that is rotatably supported by the bearing and has the hollow portion 42v formed on it. In this configuration, the hollow portion 42v is defined by an inner wall 42a formed to penetrate the shaft.

[0029] Furthermore, the second hollow shaft 42 is equipped with a drive motor for rotating the support portion 20 relative to the base portion 30. In other words, it is equipped with a drive motor for driving the second hollow shaft 42. Here, this drive motor is controlled, for example, by a receiving unit 31 or a transmitting unit 32, which will be described later.

[0030] (Base 30) The base 30 is configured to support and drive the main mirror 10 via the support 20. The base 30 also includes a receiving unit for receiving laser light LP, a transmitting unit for transmitting laser light LP, and a modem connected to the receiving unit and the transmitting unit. Here, the receiving unit is equipped with a collimator (coupler) for coupling the received laser light LP to an optical fiber, and the transmitting unit is equipped with a collimator (coupler) for forming a laser light LP for transmission from the optical signal that has propagated through the optical fiber.

[0031] As an example, as shown in Figure 1, the base unit 30 is configured to include a dichroic mirror M3, a receiving unit 31, a transmitting unit 32, and a modem 33. The dichroic mirror M3 transmits light in a specific wavelength range and reflects light outside that specific wavelength range. In the example shown in Figure 1, the dichroic mirror M3 is configured to: - transmit laser light LP in a specific wavelength range that is received by the communication device 1, and - reflect laser light LP outside that specific wavelength range that is transmitted by the communication device 1.

[0032] As a result, the dichroic mirror M3 guides the laser light LP received by the main mirror 10 to the receiving unit 31, while guiding the laser light LP for transmission provided by the transmitting unit 32 to the support unit 20. The receiving unit and transmitting unit will be described later with reference to different drawings.

[0033] (Beam size in the optical path LP) In the above-described configuration, regarding the beam size (beam diameter) of the laser light LP, the mirror surfaces of the primary mirror M11, secondary mirror M12, and mirrors M21 to M23 may be designed such that the beam size W of the received laser light LP immediately after reflection by the secondary mirror M12 and the beam size Wr of the received laser light LP immediately before it enters the receiving unit 31 are: Design Example 1: W = Wr Design Example 2: The mirror surfaces of the primary mirror M11, secondary mirror M12, and mirrors M21 to M23 may be designed such that W > Wr. In the case of Design Example 2, the received laser light LP received by the primary mirror 10 is gradually focused along the optical path from the primary mirror 10 to the base 30 and guided to the receiving unit 31. In this way, a configuration in which the received laser light LP is focused at a longer focal length is possible compared to a configuration in which it is focused within the primary mirror 10. In design example 1, the beam size Wt of the transmitted laser light LP immediately after it is emitted from the transmitting unit 32 and the beam size W of the transmitted laser light LP immediately before it is reflected by the sub-mirror M12 satisfy W = Wt, while in design example 2, W > Wt is satisfied. The specific value of W is not limited to this embodiment, but as an example, it may be a few millimeters to several tens of millimeters, or it may be a value exceeding 100 mm.

[0034] (Detailed Configuration of Communication Device 1) Next, the detailed configuration of the communication device 1 will be described with reference to Figure 3. Figure 3 is a schematic block diagram showing the configuration of the communication device 1. In Figure 3, the received laser light LP is denoted by the code Lr, and the transmitted laser light is denoted by the code Lt. The drive unit that drives the first hollow shaft 41 is denoted by the code 23, and the drive unit that drives the second hollow shaft 42 is denoted by the code 24.

[0035] The drive unit 23 includes, for example, an encoder that encodes the control signal SC1 supplied from the receiving unit 31, and a drive motor driven by the control signal SC1 encoded by the encoder. Similarly, the drive unit 24 includes, for example, an encoder that encodes the control signal SC2 supplied from the receiving unit 31, and a drive motor driven by the control signal SC2 encoded by the encoder.

[0036] As shown in Figure 3, the received laser light Lr received by the main mirror 10 is guided to the dichroic mirror M3 via the hollow section 41v formed in the first hollow shaft 41 and the hollow section 42v formed in the second hollow shaft 42. Also, as shown in Figure 3, the transmitted laser light Lt emitted from the dichroic mirror M3 is guided to the main mirror 10 via the hollow section 41v formed in the first hollow shaft 41 and the hollow section 42v formed in the second hollow shaft 42.

[0037] (Receiving Unit 31) As shown in Figure 3, the receiving unit 31 includes a first beam splitter 311, a first photodetector 312, a high-speed steering mirror 313, a second beam splitter 314, a second photodetector 315, and a collimator 316. Here, the first beam splitter 311 and the first photodetector 312, together with the drive units 23 and 24, constitute a coarse tracking mechanism for coarse tracking of the received laser light Lr. The high-speed steering mirror 313, the second beam splitter 314, and the second photodetector 315 constitute a fine tracking mechanism for fine tracking of the received laser light Lr. The coarse tracking mechanism and the fine tracking mechanism together are also referred to as the tracking mechanism 310.

[0038] (Coarse tracking mechanism) The first beam splitter 311 receives the received laser light Lr reflected by the dichroic mirror M3. The first beam splitter 311 splits the received laser light Lr into two laser beams, guides one of the laser beams to the first photodetector 312, and guides the other laser beam to the high-speed steering mirror 313.

[0039] The first photodetector 312 detects the position of the laser light incident from the first beam splitter 311 and generates control signals SC1 and SC2 according to the detection result. Here, control signal SC1 is a coarse tracking control signal around the x-axis (elevation direction) supplied to the drive unit 23 that drives the first hollow shaft 41. On the other hand, control signal SC2 is a coarse tracking control signal around the z-axis (azimuth direction) supplied to the drive unit 24 that drives the second hollow shaft 42. The specific configuration of the first photodetector 312 is not limited to this embodiment, but as an example, a four-quadrant detection element, a CCD (Charge Coupled Device) sensor, or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used.

[0040] The receiving unit 31 controls the drive units 23 and 24 with control signals SC1 and SC2, respectively, so that the main mirror unit 10 can roughly track the received laser light Lr around the x-axis (elevation direction) and the z-axis (azimuth direction), respectively.

[0041] (Precise Tracking Mechanism) Laser light that has passed through the first beam splitter 311 is incident on the high-speed steering mirror 313. The high-speed steering mirror 313 changes the path of the laser light incident on itself at high speed and with high precision according to the control signal SF from the second photodetector 315, which will be described later. The specific configuration of the high-speed steering mirror 313 is not limited to this embodiment, but as an example, a high-speed controllable mirror such as a MEMS (Micro Electro Mechanical Systems) mirror or a VCM (Voice Coil Mirror) can be used.

[0042] The second beam splitter 314 splits the laser light incident from the high-speed steering mirror 313 into two laser beams, guides one laser beam to the second photodetector 315, and guides the other laser beam to the collimator 316.

[0043] The second photodetector 315 detects the position of the laser light incident from the second beam splitter 314, and generates a control signal SF corresponding to the detection result. Here, the control signal SF is a fine tracking control signal supplied to the high-speed steering mirror 313, and includes, by way of example, a fine tracking control signal about the x-axis (elevation direction) and a fine tracking control signal about the z-axis (azimuth direction).

[0044] When the second photodetector 315 supplies the control signal SF to the high-speed steering mirror 313, the high-speed steering mirror 313, the second beam splitter 314, and the second photodetector 315 form a closed loop. By the second photodetector 315 supplying the control signal SF to the high-speed steering mirror 313, the receiving unit 31 can perform fine tracking on the received laser light Lr.

[0045] (Collimator 316) The collimator 316 collimates the laser light that has passed through the second beam splitter 314 and couples the collimated laser light into the optical fiber F31. The optical fiber F31 is connected to a modem 33.

[0046] The receiving unit 31 configured as described above can perform coarse tracking and fine tracking on the received laser light Lr received by the primary mirror unit 10, couple the tracked laser light into the optical fiber F31, and suitably supply the laser light to the modem 33.

[0047] (Transmission Unit 32) As shown in FIG. 3, the transmission unit 32 includes a collimator 321. The collimator 321 forms transmission laser light Lt from a transmission optical signal supplied from a modem 33 via an optical fiber F32. As shown in FIG. 3, the transmission laser light Lt formed by the transmission unit 32 passes through the dichroic mirror M3, penetrates the second hollow shaft 42 and the first hollow shaft 41, and is supplied to the primary mirror unit 10. Then, the transmission laser light Lt is reflected by the secondary mirror M12 and the primary mirror M11, and is emitted from the primary mirror unit 10 to the outside (transmission destination).

[0048] (Modem 33) The modem 33 acquires transmission data from a communication device not shown in the figures, and supplies received data to the communication device. As an example, the modem 33 converts an optical signal indicated by the received laser light Lr supplied from the reception unit 31 via the optical fiber F31 into a digital signal, and supplies the digital signal as received data to the communication device. In addition, the modem 33 converts transmission data acquired from the communication device into a transmission optical signal, and supplies the transmission optical signal to the transmission unit 32 via the optical fiber F32.

[0049] (Effects of Communication Device 1) As described above, the communication device 1 includes: - a primary mirror unit 10, a base 30, and - one or more hollow shafts (the first hollow shaft 41, the second hollow shaft 42) that pivotably connect the primary mirror unit 10 to the base 30; and an optical path LP for communication laser light from the primary mirror unit 10 to the base 30, which penetrates the one or more hollow shafts, is formed in the communication device 1.

[0050] As described above, in the communication device 1 according to this embodiment, an optical path LP is formed that penetrates one or more hollow axes in the optical path of the communication laser light from the main mirror section 10 to the base section 30. Therefore, the communication laser light can be guided to the base section 30 without passing through either the rotary connector for optical fiber or the rotary connector for cable. For this reason, with the above configuration, there is no need to place a collimator (coupler) and a modem on the main mirror section 10, so the moment of inertia of the main mirror section 10 can be reduced. This improves tracking performance. Furthermore, with the above configuration, since the communication laser light does not pass through either the rotary connector for optical fiber or the rotary connector for cable, a decrease in communication quality and communication speed can be suppressed.

[0051] Furthermore, as described above, the optical path LP that penetrates the one or more hollow axes (first hollow axis 41, second hollow axis 42) is an optical path that propagates in a vacuum or air, and therefore guides light from the main mirror portion 10 to the base portion 30 (or from the base portion 30 to the main mirror portion 10) without passing through an optical fiber.

[0052] Furthermore, as described above, the optical path LP includes the optical path from the main mirror section 10 to the receiving optical system (receiving section 31), and the receiving optical system (receiving section 31) is equipped with a tracking mechanism 310 (a coarse tracking mechanism and a fine tracking mechanism). Therefore, with the above configuration, the received laser light can be suitably tracked. Also, as described above, since the receiving section 31 and the modem 33 are located on the base section 30 rather than the main mirror section 10, the moment of inertia of the main mirror section 10 can be reduced. Therefore, with the above configuration, the received laser light can be tracked at high speed and with high precision.

[0053] Furthermore, as described above, the optical path LP includes the optical path from the main mirror section 10 to the transmitting optical system (transmitting section 32). Therefore, with the above configuration, the transmitted laser light can be suitably emitted. Also, as described above, since the transmitting section 32 and the modem 33 are located on the base section 30 rather than the main mirror section 10, the moment of inertia of the main mirror section 10 can be reduced. Therefore, with the above configuration, the transmitted laser light can be directed at high speed and with high precision.

[0054] Furthermore, in the above configuration, the beam size of the laser light passing through the first hollow shaft 41 and the second hollow shaft 42 is kept larger than the beam size of the optical signal propagating through the optical fiber. Therefore, even if axial wobble occurs in the first hollow shaft 41 and the second hollow shaft 42, the optical signal supplied to the modem 33 has the advantage of being less affected by the axial wobble.

[0055] (Example of the appearance of the communication device 1) Next, an example of the appearance of the communication device 1 will be described with reference to Figures 4 to 8. Figure 4 is a perspective view of the communication device 1. As described above, the communication device 1 comprises a main mirror portion 10, a support portion 20, and a base portion 30, and the main mirror portion 10 is equipped with a light-receiving window 11. Also, as shown in Figure 4, the main mirror portion 10 and the support portion 20 are rotatably connected by a first hollow shaft 41, and the support portion 20 and the base portion 30 are rotatably connected by a second hollow shaft 42. In the example shown in Figure 4, the support portion 20 comprises a support frame 201 and a housing 202 for shielding the optical path LP from the outside. Here, the housing 202 extends along the support frame 201 from the portion connected to the first hollow shaft 41 in the support frame 201 to the portion connected to the second hollow shaft 42 in the support frame 201.

[0056] Figure 5 is a front view of the communication device 1, Figure 6 is a side view (right side view) of the communication device 1, Figure 7 is a rear view of the communication device 1, and Figure 8 is a top view of the communication device 1. Note that the external appearance examples shown in Figures 4 to 8 are examples of the communication device 1 and do not limit this embodiment.

[0057] (Communication System 100) Next, with reference to Figure 9, a communication system 100 including one or more communication devices having a configuration similar to that of the communication device 1 will be described. Figure 9 is a diagram showing an example of the configuration of the communication system 100 according to this embodiment. The communication system 100 is an optical wireless communication system that performs communication by propagating laser light for communication in a vacuum or in the atmosphere.

[0058] In the example shown in Figure 9, the communication system 100 includes a first communication device 1a, a second communication device 1b, a communication device 511 located on the flying object 51, and a communication device 512 located on the flying object 52. Here, the first communication device 1a, the second communication device 1b, the communication device 511, and the communication device 512 have a configuration similar to that of the communication device 1 described above, as an example.

[0059] As shown in Figure 9, as an example, the first communication device 1a located on the ground G conducts optical wireless communication with the communication device 511 located on the flying object 51 via laser beam LA1. The communication device 511 located on the flying object 51 conducts optical wireless communication with the communication device 512 located on the flying object 52 via laser beam LA2. The communication device 512 located on the flying object 52 conducts optical wireless communication with the second communication device 1b via laser beam LA3.

[0060] As described above, the communication system 100 illustrated in Figure 9 is an optical wireless communication system that performs communication by propagating communication laser light in a vacuum or atmosphere via one or more flying objects. The configuration of the communication system 100 is not limited to the above example; for example, it may be configured to perform communication via communication devices located on one or more artificial satellites.

[0061] Furthermore, while Figure 9 shows a balloon-type flying body equipped with a propulsion system as an example of the flying bodies 51 and 52, this is not an example that limits the invention to this one. For example, the flying bodies 51 and 52 may be drones equipped with multiple propellers, or airplanes equipped with wings. Moreover, these flying bodies may be piloted by humans or automatically piloted by a predetermined algorithm. These flying bodies equipped with a communication device having a configuration similar to that of the communication device 1 are also included in the invention described herein.

[0062] [Example of implementation by software] The functions of the communication device 1 (hereinafter referred to as "device") may be implemented by a program that causes a computer to function as the device, and which causes a computer to function as each control block of the device (especially each part included in the receiving unit 31).

[0063] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, the functions described in each of the embodiments are realized.

[0064] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0065] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0066] Furthermore, each process described in the above embodiments may be performed by AI (Artificial Intelligence). In this case, the AI ​​may operate on the control device described above, or it may operate on another device (for example, an edge computer or a cloud server).

[0067] (Additional Notes) This specification includes at least the following components:

[0068] (Configuration 1) A communication device comprising: a primary mirror section; a base section; and one or more hollow shafts rotatably connecting the primary mirror section to the base section, wherein an optical path for communication laser light from the primary mirror section to the base section is formed, and the optical path penetrates the one or more hollow shafts.

[0069] (Configuration 2) The communication device according to Configuration 1, wherein the optical path is an optical path that propagates in a vacuum or in air.

[0070] (Configuration 3) The communication device according to Configuration 2, wherein the optical path includes an optical path from the main mirror to the receiving optical system located at the base.

[0071] (Configuration 4) The communication device according to Configuration 3, wherein the receiving optical system is equipped with a tracking mechanism for tracking the communication laser light.

[0072] (Configuration 5) The communication device according to Configuration 1, wherein the optical path includes an optical path from the main mirror to the transmitting optical system located at the base.

[0073] (Configuration 6) A communication device according to any one of Configurations 1 to 5, comprising a support portion for supporting the main mirror portion, wherein the one or more hollow shafts include a first hollow shaft that connects the main mirror portion to the support portion so as to be rotatable around a first axis, and a second hollow shaft that connects the support portion to the base portion so as to be rotatable around a second axis that is not parallel to the first axis.

[0074] (Configuration 7) The optical wireless communication device according to Configuration 6, wherein one or more mirrors that reflect the communication laser light are arranged in the optical path.

[0075] (Configuration 8) The optical wireless communication device according to Configuration 7, wherein the support portion is a housing for shielding the optical path from the outside world.

[0076] (Configuration 9) A communication system comprising a plurality of communication devices, wherein at least one of the plurality of communication devices comprises: a main mirror portion, a base portion, and one or more hollow shafts that rotatably connect the main mirror portion to the base portion, and a communication laser light optical path from the main mirror portion to the base portion is formed, the optical path passing through the one or more hollow shafts.

[0077] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0078] Furthermore, this invention suppresses the deterioration of communication quality and communication speed in optical wireless communication technology, improves tracking performance, and serves as an innovative technological foundation for the telecommunications business, thereby contributing to the achievement of Sustainable Development Goal (SDG) 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0079] 1 ... Communication device 10 ... Primary mirror section 20 ... Support section 30 ... Base section 31 ... Receiving section (receiving optical system) 32 ... Transmitting section (transmitting optical system) 41 ... First hollow axis 42 ... Second hollow axis M11 ... Primary mirror M12 ... Secondary mirror M21-M23 ... Mirrors M3 ... Dichroic mirror LP ... Optical path 100 ... Communication system

Claims

1. A communication device comprising: a primary mirror; a base; and one or more hollow shafts rotatably connecting the primary mirror to the base, wherein an optical path for communication laser light from the primary mirror to the base is formed, the optical path passing through the one or more hollow shafts.

2. The communication device according to claim 1, wherein the optical path is an optical path that propagates in a vacuum or in air.

3. The communication device according to claim 2, wherein the optical path includes an optical path from the main mirror to the receiving optical system located at the base.

4. The communication device according to claim 3, wherein the receiving optical system is equipped with a tracking mechanism for tracking the communication laser light.

5. The communication device according to claim 1, wherein the optical path includes an optical path from the main mirror to the transmitting optical system located at the base.

6. A communication device according to any one of claims 1 to 5, comprising a support portion for supporting the primary mirror portion, wherein the one or more hollow shafts include a first hollow shaft that connects the primary mirror portion to the support portion so as to be rotatable around a first axis, and a second hollow shaft that connects the support portion to the base portion so as to be rotatable around a second axis that is not parallel to the first axis.

7. The communication device according to claim 6, wherein one or more mirrors that reflect the communication laser light are arranged in the optical path.

8. The communication device according to claim 7, wherein the support portion comprises a housing for shielding the optical path from the outside world.

9. A communication system comprising a plurality of communication devices, wherein at least one of the plurality of communication devices comprises: a primary mirror portion, a base portion, and one or more hollow shafts rotatably connecting the primary mirror portion to the base portion, and a communication laser beam optical path from the primary mirror portion to the base portion is formed, the optical path passing through the one or more hollow shafts.

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