Correction device and communication device

Abstract

In optical wireless communication, this technology enables high-speed correction of the communication laser beam. [Solution] The correction device (100) comprises a plurality of driveable mirrors (M101, M102, ...) arranged on the optical path of the communication laser light, a detection unit (120) that detects the communication laser light reflected by the plurality of driveable mirrors, and a drive unit (130) that drives each of the plurality of driveable mirrors according to the detection result of the detection unit, and drives the first driveable mirror and the second driveable mirror among the plurality of driveable mirrors at different timings.

Description

Technical Field

[0001] The present disclosure relates to a correction device for correcting laser light for communication and a communication device.

Background Art

[0002] Development of optical wireless communication technology for performing communication by propagating highly directional light through a flying object, an artificial satellite, etc. in a vacuum or the atmosphere has been carried out (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0004] A correction device according to an aspect of the present disclosure includes a plurality of driven mirrors disposed on an optical path of laser light for communication, a detection unit that detects the laser light for communication reflected by the plurality of driven mirrors, and a drive unit that drives each of the plurality of driven mirrors according to a detection result by the detection unit, the drive unit driving a first driven mirror and a second driven mirror among the plurality of driven mirrors at different timings from each other.

Brief Description of the Drawings

[0005] [Figure 1] It is a schematic diagram showing the configuration of a correction device according to an embodiment. [Figure 2] It is a diagram for explaining a correction device according to an embodiment. [Figure 3] It is a schematic diagram showing the configuration of a correction device according to an embodiment. [Figure 4] It is a schematic front view of a communication device according to an embodiment. [Figure 5]This is a schematic cross-sectional view of a communication device according to an embodiment. [Figure 6] This is a schematic block diagram showing the configuration of a communication device according to the embodiment. [Figure 7] This is a cross-sectional view showing the configuration of a mirror device according to an embodiment. [Figure 8] This is a diagram showing an example configuration of a communication system according to the embodiment. [Modes for carrying out the invention]

[0006] Hereinafter, one embodiment of this disclosure will be described in detail with reference to the drawings. For ease of understanding, the background and challenges of this disclosure will be described first, followed by a detailed description of the disclosure.

[0007] <Background and Challenges> Optical wireless communication technology is known for transmitting highly directional light, such as laser light, through a vacuum or atmosphere via flying objects or satellites. In optical wireless communication, optical wireless communication devices that receive laser light from a moving communication partner, such as a flying object, or transmit laser light to that communication partner, require a tracking and correction mechanism (also simply called a correction mechanism) to track the communication partner and correct for deviations in the laser light due to vibration or atmospheric turbulence. Such a correction mechanism requires the mirror to be driven as fast as possible, but there is generally a limit to the driving speed of a mirror.

[0008] One aspect of this disclosure aims to provide a technology that enables faster correction of laser light used for communications.

[0009] <Overview of Correction Device 100> The correction device 100 according to this embodiment is, for example, a device for correcting communication laser light used in optical wireless communication. As described below, the correction device 100 is, • Multiple drive mirrors positioned along the optical path of the communication laser beam, A detection unit for detecting the communication laser light reflected by the plurality of driven mirrors, A drive unit that drives each of the plurality of driveable mirrors according to the detection result of the detection unit, wherein the drive unit drives the first driveable mirror and the second driveable mirror among the plurality of driveable mirrors at different timings. It is equipped with.

[0010] As described above, the correction device 100 according to this embodiment is equipped with a plurality of driveable mirrors, and the first driveable mirror and the second driveable mirror are driven at different timings from each other. Therefore, compared to a configuration using a single driveable mirror, the communication laser beam can be corrected at a higher speed. In this specification, the term "correction" includes at least one of the position correction (tracking), beam diameter correction, and wavefront correction of the communication laser beam. Furthermore, the name "correction device" is not limited to this embodiment and may also be called a tracking device, etc.

[0011] (Configuration of the correction device 100) The configuration of the correction device 100 will be explained with reference to Figures 1 to 3. Figure 1 is a schematic cross-sectional view of the correction device 100. As shown in Figure 1, the correction device 100 includes a plurality of driveable mirrors (first driveable mirror M101, second driveable mirror M102), a detection unit 120, a drive unit 130, and a beam splitter. The plurality of driveable mirrors may also be referred to as the driveable mirror group 110.

[0012] As shown in Figure 1, the communication laser beam LP is incident on the correction device 100 and is sequentially reflected by the first driven mirror M101 and the second driven mirror M102, which are positioned on the optical path of the communication laser beam LP. The communication laser beam LP reflected by the second driven mirror M102 then passes through the beam splitter 140 and is emitted from the correction device 100. The communication laser beam LP is also supplied from the beam splitter 140 to the detection unit 120. The communication laser beam LP emitted from the correction device 100 is supplied, for example, to a receiving device (receiving unit) located downstream of the correction device 100. The communication laser beam LP emitted from the correction device 100 is sometimes referred to as the communication laser beam LP after correction by the correction device 100.

[0013] (Driven mirror group 110) The first driveable mirror M101 and the second driveable mirror M102, which constitute the driveable mirror group 110, are driven by a first control signal SF1 and a second control signal SF2 from a drive unit 130, which will be described later. The first driveable mirror M101, for example, includes a first mirror portion that reflects communication laser light LP and a first drive mechanism that drives the first mirror portion in accordance with the first control signal SF1, but this configuration is not limited to this embodiment. Similarly, the second driveable mirror M102, for example, includes a second mirror portion that reflects communication laser light LP and a second drive mechanism that drives the second mirror portion in accordance with the second control signal SF2, but this configuration is not limited to this embodiment. Furthermore, as the first driven mirror M101 and the second driven mirror M102, examples include MEMS mirrors employing a MEMS (Micro Electro Mechanical Systems) drive mechanism, and high-speed controllable mirrors such as VCMs (Voice Coil Mirrors).

[0014] (Beam Splitter 140) The beam splitter 140 splits the communication laser beam LP reflected by the plurality of driven mirrors M101, M102 into two laser beams, guides one laser beam outside the correction device 100, and guides the other laser beam to the detection unit 120.

[0015] (Detection unit 120) The detection unit 120 detects the communication laser beam LP guided by the beam splitter 140. In other words, the detection unit 120 detects the communication laser beam LP reflected by the plurality of driven mirrors M101, M102. As an example, the detection unit 120 · The beam position of the communication laser beam LP · The beam diameter of the communication laser beam LP · The wavefront of the communication laser beam LP can be configured to detect at least any one of them. The detection unit 120 supplies a signal indicating the detection result to the drive unit 130.

[0016] (Drive unit 130) The drive unit 130 drives each of the plurality of driven mirrors M101, M102 according to the detection result by the detection unit 120. As an example, the drive unit 130 drives the first driven mirror M101 and the second driven mirror M102 at different timings. For example, the drive unit 130 can be configured to drive these driven mirrors by supplying the first control signal SF1 and the second control signal SF2 to the first driven mirror M101 and the second driven mirror M102, respectively.

[0017] Note that the driving method by the drive unit 130 is · Driving the first driven mirror M101 and the second driven mirror M102 alternately · Driving the first driven mirror M101 and the second driven mirror M102 intermittently can also be expressed as follows.

[0018] The upper part of Figure 2 shows examples of the first control signal SF1 and the second control signal SF2 that the drive unit 130 supplies to the first driveable mirror M101 and the second driveable mirror M102, respectively. As shown in the upper part of Figure 2, the drive unit 130 periodically drives the first driveable mirror M101 and the second driveable mirror M102, as an example. The drive unit 130 also drives each of the plurality of driveable mirrors by supplying control signals with different phases to the first driveable mirror M101 and the second driveable mirror M102.

[0019] In the example shown in the upper part of Figure 2, the drive unit 130 drives the first driveable mirror M101 and the second driveable mirror M102 by control signals SF1 and SF2 with period T. More specifically, the drive unit 130, The first drive-type mirror M101 is controlled by a pulse-type control signal SF1 having a period t1 in which the pulse height is not zero during a period T which is one cycle. The second drive-type mirror M102 is controlled by a pulse-type control signal SF2, which has a period t2 in which the pulse height is not zero during a period T that is one cycle. Here, as shown in the upper part of Figure 2, the period t1 in which the pulse height is not zero in control signal SF1 and the period t2 in which the pulse height is not zero in control signal SF2 are at different timings. In other words, the phases of control signal SF1 and control signal SF2 are different. More specifically, as shown in the upper part of Figure 2, the phases of control signal SF1 and control signal SF2 are π (180°) apart.

[0020] The specific driving frequency of the multiple drive-type mirrors by the drive unit 130 is not limited to this embodiment, but as an example, it can be 1 kHz or higher. More specifically, the period T value in the control signals SF1 and SF2 can be 1 ms (milliseconds) or less.

[0021] (Distance between drive mirrors) The distance between the first driveable mirror M101 and the second driveable mirror M102 described above is not limited to this embodiment, but it is preferable to set it as described below as an example. The lower part of Figure 2 is a diagram illustrating an example distance between the first driveable mirror M101 and the second driveable mirror M102.

[0022] As shown in the lower part of Figure 2, the mirror diameter of the first drive-type mirror M101 is denoted as R1, the mirror diameter of the second drive-type mirror M102 is denoted as R2, and the distance between the first drive-type mirror M101 and the second drive-type mirror M102 is denoted as D. Here, the distance D is defined, for example, as the distance between the mirror center of the first drive-type mirror M101 and the mirror center of the second drive-type mirror M102. At this time, the correction device 100, D ≤ k × R 1 D ≤ k × R² It is preferable that the arrangement satisfies at least one of the following conditions. Here, k is a constant, for example 2 (the separation distance D is less than or equal to twice the mirror diameter), but it is more preferable that it be 1 (the separation distance D is less than or equal to the mirror diameter).

[0023] (Configuration with three or more driveable mirrors) In the above example, the correction device 100 was mainly described in which a driveable mirror is provided (M101, M102), but this is not limited to this embodiment. The correction device 100 may also be configured to provide three or more driveable mirrors. As an example of such a configuration, Figure 3 shows an example in which the correction device 100 is provided with three driveable mirrors (M101, M102, M103).

[0024] As shown in Figure 3, the drive mirror group 110 is equipped with three drive mirrors (M101, M102, M103), and the communication laser light LP incident on the correction device 100 is sequentially reflected by the first drive mirror M101, the second drive mirror M102, and the third drive mirror M103, and guided to the beam splitter 140.

[0025] The drive unit 130 drives each of the multiple driveable mirrors M101, M102, and M103 according to the detection result from the detection unit 120. For example, the drive unit 130 drives the first driveable mirror M101, the second driveable mirror M102, and the third driveable mirror M103 at different timings. For example, the drive unit 130 drives each of the multiple driveable mirrors by supplying control signals (SF1, SF2, SF3) with different phases to the first driveable mirror M101, the second driveable mirror M102, and the third driveable mirror M103. For example, control signals SF1 supplied to the first driveable mirror M101, SF2 supplied to the second driveable mirror M102, and SF3 supplied to the third driveable mirror M103 can be used, with a phase difference of 2π / 3 (120°) from each other.

[0026] (Effect of correction device 100) As explained above, the correction device 100 according to this embodiment is • Multiple driveable mirrors (M101, M102, M103) are positioned along the optical path of the communication laser beam LP, A detection unit 120 that detects the communication laser light LP reflected by the plurality of drive mirrors, A drive unit 130 that drives each of the plurality of driveable mirrors according to the detection result of the detection unit 120, wherein the drive unit 130 drives the first driveable mirror M101 and the second driveable mirror M102 of the plurality of driveable mirrors at different timings. It is equipped with.

[0027] Thus, the correction device 100 according to this embodiment is equipped with multiple driveable mirrors, and the first driveable mirror and the second driveable mirror are driven at different timings from each other. As a result, the communication laser light can be corrected at a higher speed compared to a configuration using a single driveable mirror.

[0028] As an example, in a configuration in which the correction device 100 includes a first driveable mirror M101 and a second driveable mirror M102, when the drive unit 130 drives the first driveable mirror M101 and the second driveable mirror M102 using control signals SF1 and SF2 that have a phase difference of π (180°) from each other, the communication laser beam LP can be corrected at approximately twice the speed compared to a configuration with only one driveable mirror.

[0029] As another example, in a configuration where the correction device 100 includes a first driveable mirror M101, a second driveable mirror M102, and a third driveable mirror M103, if the drive unit 130 drives the first driveable mirror M101, the second driveable mirror M102, and the third driveable mirror M103 using control signals SF1, SF2, and SF3 which have a phase difference of 2π / 3 (120°) from each other, the communication laser beam LP can be corrected at approximately three times the speed compared to a configuration with only one driveable mirror.

[0030] (Configuration of communication device 1) The configuration of the communication device 1 equipped with the correction device 100 described above will be explained below with reference to Figures 4 to 6. The communication device 1 is, for example, an optical wireless communication device that communicates by propagating communication laser light in a vacuum or atmosphere via a flying object or artificial satellite. Figure 4 is a schematic front view of the communication device 1, and Figure 5 is a schematic cross-sectional view of the communication device 1. For the sake of explanation, in Figures 4 and 5, 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 direction is positive for the z-axis.

[0031] As shown in Figure 4, 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 comprises... • A first hollow shaft 41 connects the main mirror section 10 to the support section 20 so that it can rotate around the x-axis (first axis), and • A second hollow shaft 42 connects the support portion 20 to the base portion 30 so that it can rotate around the z-axis (second axis), which is non-parallel to the x-axis (first axis). It is equipped with the following. Here, the x-axis and the z-axis perpendicular to the x-axis have been given as examples of the first and second axes, respectively, but this is not limited to this embodiment, and the first and second axes do not need to be parallel. Also, the number of hollow axes provided by the communication device 1 is not limited to the above example, and may be one or three or more.

[0032] (Main mirror section 10) As shown in Figure 4, 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. Furthermore, the light-receiving window 11 may also function as a lens that refracts the communication laser light.

[0033] Figure 5 is a cross-sectional view obtained by cutting the communication device 1 through a section including the optical path LP of the communication laser light in the communication device 1. As shown in Figure 5, 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 based on 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.

[0034] The communication laser light incident on the primary mirror section 10 from the front side (the near side of the paper in Figure 5, 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 further forward than 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 5.

[0035] In Figure 5, 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 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 optical path through which the communication laser beam LP propagates within the communication device 1 is also sometimes referred to as optical path LP using the same symbol LP. Therefore, symbols L1 and L2 can also be considered as symbols that define the ends (edges) of the optical path LP.

[0036] (First hollow shaft 41) The first hollow shaft 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 shaft 41. Here, as shown in Figure 5, the hollow portion 41v is a hollow region defined by the inner wall 41a of the first hollow shaft 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.

[0037] 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.

[0038] 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.

[0039] (Support part 20) The support portion 20 supports the main mirror portion 10 relative to the base portion 30. The designation of the support portion 20 is not limited to this embodiment, and it may also be called a support frame or gimbal frame, etc.

[0040] As shown in Figure 5, 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 5, 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. Furthermore, 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.

[0041] Furthermore, when the communication device 1 is located on the Earth's surface or in the atmosphere, the cavity through which the laser beam LP is guided in the support portion 20 is filled with air or with a gas filled inside the communication device 1. As another example, when the communication device 1 is located 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.

[0042] 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 relative to the base portion 30 and a housing for shielding the optical path of the communication laser light LP from the outside world.

[0043] (Second hollow shaft 42) The second hollow shaft 42 connects the support portion 20 to the base portion 30 so that it can rotate 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 shaft 42. Here, as shown in Figure 5, the hollow portion 42v is a hollow region defined by the inner wall 42a of the second hollow shaft 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 are not limiting to this embodiment.

[0044] 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.

[0045] 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.

[0046] (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 includes, for example, a collimator (coupler) for coupling the received laser light LP to an optical fiber, and the transmitting unit includes a collimator (coupler) for forming the laser light LP for transmission from the optical signal propagating through the optical fiber.

[0047] As an example, as shown in Figure 5, 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 5, the dichroic mirror M3 is • A laser light LP in a specific wavelength range, which is transmitted through the laser light LP received by the communication device 1. • Laser light LP outside the specific wavelength range is configured to reflect the laser light LP transmitted by the communication device 1.

[0048] As a result, the dichroic mirror M3 guides the laser light LP received by the main mirror section 10 to the receiving section 31, while guiding the laser light LP for transmission provided by the transmitting section 32 to the support section 20. The receiving section and transmitting section will be described later with reference to different drawings.

[0049] (Beam size in optical path LP) Furthermore, in the above-described configuration, regarding the beam size (beam diameter) of the laser light LP, the beam size W of the received laser light LP immediately after reflection by the sub-mirror M12 and the beam size Wr of the received laser light LP immediately before it enters the receiving unit 31 are as follows: Design Example 1: W=Wr The mirror surfaces of the primary mirror M11, secondary mirror M12, and mirrors M21-M23 may be designed in such a way. Design Example 2: W>Wr The mirror surfaces of the primary mirror M11, secondary mirror M12, and mirrors M21-M23 may be designed accordingly. In 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 may be used compared to a configuration in which it is focused within the primary mirror 10. Note that 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 secondary mirror M12 are, W=Wt The following conditions are met, and in the case of design example 2, W>Wt This will satisfy the condition. Note that the specific value of W mentioned above 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.

[0050] (Detailed configuration of communication device 1) Next, the detailed configuration of the communication device 1 will be described with reference to Figure 6. Figure 6 is a schematic block diagram showing the configuration of the communication device 1. In Figure 6, the received laser light LP is denoted by the code Lr, and the transmitted laser light is denoted by the code Lt. In addition, 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.

[0051] 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.

[0052] As shown in Figure 6, 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 axis 41 and the hollow section 42v formed in the second hollow axis 42. Also, as shown in Figure 6, 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 axis 41 and the hollow section 42v formed in the second hollow axis 42.

[0053] (Receiving unit 31) As shown in Figure 6, the receiving unit 31 includes a first beam splitter 311, a first photodetector 312, a correction device 100, and a collimator 316. Here, the correction device 100 includes a drive-type mirror group 110, a detection unit 120 (also called a second photodetector), a drive unit 130, and a beam splitter 140 (also called a second beam splitter), as described above. 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. On the other hand, the correction device 100 constitutes 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.

[0054] (Rough 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, guiding one of them to the first photodetector 312 and the other to the high-speed steering mirror 313.

[0055] 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.

[0056] 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.

[0057] (Precise tracking mechanism: correction device 100) Laser light that has passed through the first beam splitter 311 is incident on the driven mirror group 110. The incident laser light is sequentially reflected, for example, by the first driven mirror M101 and the second driven mirror M102 of the driven mirror group 110. Details of the driven mirror group 110 have been described above, so a redundant explanation will be omitted.

[0058] The beam splitter 140 splits the laser light incident from the driven mirror group 110 into two laser beams, guides one of the laser beams to the detection unit 120, and guides the other laser beam to the collimator 316.

[0059] The detection unit 120 (second photodetector) detects the communication laser light LP guided by the beam splitter 140. The drive unit 130 generates a control signal SF according to the detection result by the detection unit 120 and drives each of the drive mirrors (M101, M102, ...) included in the drive mirror group 110 by supplying the generated control signal SF to the drive mirror group 110. Here, the control signal SF includes at least one of the control signals SF1 to SF3, which were described with reference to Figures 1 and 2 as an example. Details of the detection unit 120 and the drive unit 130 have been described above, so redundant explanations will be omitted.

[0060] (Collimator 316) The collimator 316 collimates the laser light that has passed through the beam splitter 140 (second beam splitter) and couples it to the optical fiber F31. The optical fiber F31 is connected to the modem 33.

[0061] The receiving unit 31, configured as described above, can coarsely and precisely track the received laser light Lr received by the main mirror unit 10, couple it to the optical fiber F31, and supply it to the modem 33.

[0062] (Transmitter 32) As shown in Figure 6, the transmitting unit 32 is equipped with a collimator 321. The collimator 321 forms a transmitted laser beam Lt from the optical signal for transmission supplied from the modem 33 via the optical fiber F32. As shown in Figure 3, the transmitted laser beam Lt formed by the transmitting 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 main mirror unit 10. It is then reflected by the secondary mirror M12 and the main mirror M11 and emitted from the main mirror unit 10 to the outside world (transmission destination).

[0063] (Modem 33) The modem 33 acquires transmission data from a communication device (not shown) and supplies received data to the same communication device. For example, the modem 33 converts the optical signal indicated by the received laser light Lr supplied from the receiving unit 31 via the optical fiber F31 into a digital signal and supplies the digital signal as received data to the communication device. The modem 33 also converts the transmission data acquired from the communication device into an optical signal for transmission and supplies it to the transmitting unit 32 via the optical fiber F32.

[0064] As described above, the communication device 1 according to this embodiment is equipped with a correction device 100, which enables high-speed tracking and correction of the laser light received by the communication device 1. Therefore, the communication device 1 can suppress a decrease in communication quality and communication speed in optical wireless communication.

[0065] (Mirror device 110) The driven mirror group 110 described above can also be considered as the mirror device 110 according to this embodiment. The configuration of the mirror device 110 according to this embodiment will be described below with reference to Figure 7.

[0066] Figure 7 is a schematic cross-sectional view showing the configuration of the mirror device 110 according to this embodiment. As shown in Figure 7, the mirror device 110 comprises a first mirror section M101, a first drive mechanism 101a, a first substrate 101b, a second mirror section M102, a second drive mechanism 102a, a second substrate 102b, and a package (housing) 111.

[0067] Here, the first mirror section M101, the first drive mechanism 101a, and the first substrate 101b constitute a first drive-type mirror as described with reference to Figures 1 to 3, as an example. Also, the second mirror section M102, the second drive mechanism 102a, and the second substrate 102b constitute a second drive-type mirror as described with reference to Figures 1 to 3, as an example.

[0068] Although Figure 7 illustrates a configuration of a mirror device 110 having two mirror sections, this is not limited to this embodiment. A mirror device 110 having two or more mirror sections is also included in this embodiment.

[0069] (Package 111) The package 111 contains (encloses) the mirror device 110, which includes a first mirror section M101, a first drive mechanism 101a, a first substrate 101b, a second mirror section M102, a second drive mechanism 102a, and a second substrate 102b. For example, the package 111 permanently houses the first substrate 101b and the second substrate 102b within the package 111. As shown in Figure 7, the package 111 also has a first window section W1 and a second window section W2. The first window section W1 and the second window section W2 are configured to transmit communication laser light while maintaining airtightness within the package 111.

[0070] (Circuit board, drive mechanism) The first substrate 101b and the second substrate 102b are each equipped with a first drive mechanism 101a and a second drive mechanism 102a, respectively, for driving the first mirror portion M101 and the second mirror portion M102. Here, the first drive mechanism 101a and the second drive mechanism 102a may, for example, be drive mechanisms using MEMS (Micro Electro Mechanical Systems) or drive mechanisms using VCM (Voice Coil Motor). Furthermore, the first drive mechanism 101a and the second drive mechanism 102a may be driven by control signals SF1 and SF2, as described with reference to Figure 1, for example. However, this is not limited to this configuration example.

[0071] As shown in Figure 7, the first mirror portion M101, the first drive mechanism 101a, and the first substrate 101b are arranged non-parallel to the first window portion W1 and the second window portion W2 within the package 111. More specifically, the first mirror portion M101, the first drive mechanism 101a, and the first substrate 101b are arranged such that their normal vectors form an angle of 45° or 135° with respect to the normal vectors of the first window portion W1 and the second window portion W2. Similarly, the second mirror portion M102, the second drive mechanism 102a, and the second substrate 102b are arranged such that their normal vectors form an angle of 45° or 135° with respect to the normal vectors of the first window portion W1 and the second window portion W2. Furthermore, the first mirror portion M101 and the second mirror portion M102 are positioned so as to face each other (the angle between their respective normal vectors is 180°).

[0072] By adopting this arrangement, for example, the communication laser light that enters the package 111 from the first window W1 is reflected by the first mirror M101, then reflected by the second mirror M102, and then emitted out of the package 111 from the second window W2.

[0073] Thus, in the mirror device 110, the incident communication laser light is reflected by multiple driven mirrors before being emitted. For example, by driving each of these multiple driven mirrors at different timings as described above, the communication laser light can be corrected at a higher speed compared to a configuration with only one driven mirror.

[0074] (Communication system 1000) Next, with reference to Figure 8, a communication system 1000 including one or more communication devices having a configuration similar to that of communication device 1 will be described. Figure 8 is a diagram showing an example configuration of the communication system 1000 according to this embodiment. The communication system 1000 is an optical wireless communication system that performs communication by propagating laser light for communication in a vacuum or in the atmosphere.

[0075] In the example shown in Figure 8, the communication system 1000 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.

[0076] As shown in Figure 8, 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.

[0077] As described above, the communication system 1000 illustrated in Figure 8 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 1000 is not limited to the above example; for example, it may also be configured to perform communication via communication devices located on one or more artificial satellites.

[0078] Furthermore, while Figure 8 shows a balloon-type flying object equipped with a propulsion system as an example of the flying objects 51 and 52, this is not an example that limits the invention to this one. For example, the flying objects 51 and 52 may be drones equipped with multiple propellers or airplanes equipped with wings. Moreover, these flying objects may be piloted by humans or automatically piloted by a predetermined algorithm. These flying objects equipped with a communication device having a configuration similar to that of communication device 1 are also included in the invention described herein.

[0079] [Examples of implementation using software] The function of the communication device 1 (hereinafter referred to as "the device") may be realized by a program that causes the device to function as a computer, and which causes each control block of the device (in particular each part included in the receiving unit 31) to function as a computer.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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 other devices (for example, an edge computer or a cloud server).

[0084] (Additional notes) This specification describes at least the following configurations:

[0085] (Composition 1) Multiple driveable mirrors positioned along the optical path of a communication laser beam, A detection unit for detecting the communication laser light reflected by the plurality of drive mirrors, A drive unit that drives each of the plurality of driveable mirrors according to the detection result of the detection unit, wherein the drive unit drives the first driveable mirror and the second driveable mirror among the plurality of driveable mirrors at different timings. A correction device equipped with this device.

[0086] (Configuration 2) The aforementioned drive unit is The first driveable mirror and the second driveable mirror are driven periodically. Each of the plurality of drive mirrors is driven by supplying control signals with different phases to the first drive mirror and the second drive mirror. The correction device described in Configuration 1.

[0087] (Composition 3) The aforementioned multiple drive-type mirrors are MEMS mirrors. The correction device described in Configuration 2.

[0088] (Composition 4) The frequency of the periodic drive by the drive unit is 1 kHz or higher. The correction device described in configuration 3.

[0089] (Composition 5) The distance between the first driveable mirror and the second driveable mirror is less than twice the mirror diameter of at least one of the first driveable mirror and the mirror diameter of the second driveable mirror. A correction device as described in any one of items 1 to 4 of the configuration.

[0090] (Composition 6) A correction device described in any one of configurations 1 to 4, A beam splitter into which the communication laser light reflected by the plurality of driven mirrors is incident, the beam splitter supplying a portion of the incident communication laser light to the detection unit, A collimator that collimates the remaining portion of the communication laser light supplied from the beam splitter and couples it to an optical fiber. A communication device equipped with the following features.

[0091] 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.

[0092] 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." [Explanation of symbols]

[0093] 1. Communication device 100 ··· Correction device 110 ···Driven mirror group 120 ···Detection unit 130 ···Drive unit M101 ··First drive mirror, first mirror section M102 ··Second drive mirror, second mirror section 1000 ··Communication System

Claims

1. Multiple driveable mirrors arranged along the optical path of a communication laser beam, A detection unit for detecting the communication laser light reflected by the plurality of drive mirrors, A drive unit that drives each of the plurality of driveable mirrors according to the detection result of the detection unit, wherein the drive unit drives the first driveable mirror and the second driveable mirror among the plurality of driveable mirrors at different timings. Equipped with, The aforementioned drive unit is The first driveable mirror and the second driveable mirror are driven periodically in a cycle that includes a period of driving and a period of not driving. Each of the plurality of drive mirrors is driven by supplying control signals to the first drive mirror and the second drive mirror, which have different phases from each other, and which drive the other during periods when the other is not driven. Correction device.

2. The aforementioned multiple drive-type mirrors are MEMS mirrors. The correction device according to claim 1.

3. The frequency of the periodic drive by the drive unit is 1 kHz or higher. The correction device according to claim 2.

4. The distance between the center of the first drive mirror and the center of the second drive mirror is less than twice the mirror diameter of at least one of the first drive mirror and the mirror diameter of the second drive mirror. A correction device according to any one of claims 1 to 3.

5. A correction device according to any one of claims 1 to 3, A beam splitter into which the communication laser light reflected by the plurality of driven mirrors is incident, the beam splitter supplying a portion of the incident communication laser light to the detection unit, A collimator that collimates the remaining portion of the communication laser light supplied from the beam splitter and couples it to an optical fiber. A communication device equipped with the following features.

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