Optical space communication device, control method for optical space communication device, and program

Abstract

This invention realizes an optical spatial communication device that can receive light beams over a wide angular range, enabling confirmation of the direction of the communication target. [Solution] The optical spatial communication device includes: an aspherical mirror having an optical axis and reflecting spatial communication light incident on the optical axis at an angle greater than a first angle greater than 0° and less than a second angle less than 180° in a direction along the optical axis; a reflective member that reflects at least a portion of the spatial communication light reflected by the aspherical mirror in a direction along the optical axis; and an image sensor that receives the spatial communication light reflected by the reflective member and outputs image data representing an image including bright areas corresponding to the spatial communication light.

Description

Technical Field

[0001] The present disclosure relates to an optical space communication device, a control method for the optical space communication device, and a program.

Background Art

[0002] Optical space communication using the spatial propagation of light is used. Patent Document 1 discloses a technique for optical space communication that acquires the direction information of an optical beam emitted from a target object and directs an optical unit toward the target object based on the direction information. This direction information can be obtained, for example, from the target object itself or from outside the target object.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the direction information of the optical beam cannot always be obtained. In this case, it is not easy to direct the optical unit toward the target object.

[0005] The present disclosure has been made in view of the above problems, and an exemplary object thereof is to provide an optical space communication device, a control method for the optical space communication device, and a program that can receive an optical beam in a wide angle range and confirm the direction of a communication target.

Means for Solving the Problems

[0006] An optical spatial communication device relating to an exemplary aspect of the present disclosure includes: an aspherical mirror having an optical axis and reflecting spatial communication light incident on the optical axis at an angle greater than a first angle greater than 0° and less than a second angle less than 180° in a direction along the optical axis; a reflective member that reflects at least a portion of the spatial communication light reflected by the aspherical mirror in a direction along the optical axis; and an image sensor that receives the spatial communication light reflected by the reflective member and outputs image data representing an image including bright areas corresponding to the spatial communication light. [Effects of the Invention]

[0007] According to an illustrative aspect of this disclosure, one exemplary effect is that it is possible to receive a light beam over a wide angular range and confirm the direction of the communication target. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the configuration of the optical spatial communication device related to this disclosure. [Figure 2] This is a diagram illustrating an example of an aspherical mirror. [Figure 3] This is a block diagram showing the configuration of the optical spatial communication device related to this disclosure. [Figure 4] This figure shows an example of an image represented by video data output from an image sensor. [Figure 5] This diagram shows the adjustment of the viewing angle using the viewing angle adjustment unit. [Figure 6] This is a block diagram showing the configuration of the optical spatial communication device related to this disclosure. [Figure 7] This flowchart shows the flow of the control method for the optical space communication device related to this disclosure. [Figure 8] This is a block diagram showing the configuration of the optical spatial communication device related to this disclosure. [Figure 9] This is a block diagram showing the configuration of the optical spatial communication device related to this disclosure. [Figure 10] This is a block diagram showing the configuration of a computer that functions as an optical space communication device related to this disclosure. [Modes for carrying out the invention]

[0009] The following are examples of embodiments of the present invention. However, the present invention is not limited to the exemplary embodiments shown below, and various modifications are possible within the scope of the claims. For example, embodiments obtained by appropriately combining some or all of the technologies (things or methods) employed in each of the exemplary embodiments shown below may also be included in the scope of the present invention. Furthermore, embodiments obtained by appropriately omitting some of the technologies employed in each of the exemplary embodiments shown below may also be included in the scope of the present invention. In addition, the effects mentioned in each of the exemplary embodiments shown below are examples of effects that can be expected in that exemplary embodiment and do not define the scope of the present invention. That is, embodiments that do not produce the effects mentioned in each of the exemplary embodiments shown below may also be included in the scope of the present invention.

[0010] [First Exemplary Embodiment] A first exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to Figure 1. This exemplary embodiment is the basic form for each of the exemplary embodiments described later. The scope of application of each technology adopted in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology adopted in this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical problems occur. Furthermore, each technology shown in the drawings referenced to explain this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical problems occur.

[0011] (Configuration of optical space communication device) The optical space communication device 1 according to the first exemplary embodiment includes an aspherical mirror 11, a reflective member 21a, and an image sensor 22.

[0012] The aspherical mirror 11 has an optical axis C. The aspherical mirror 11 reflects the space communication light Li incident at an angle (elevation angle) θ greater than 0° and less than or equal to a second angle θ2 less than 180° with respect to the optical axis C in the direction along the optical axis C. The direction along the optical axis C means not only the direction parallel to the optical axis C but also that a certain angular range is allowed with respect to the optical axis C. This angular range may be the angular range within which the light reflected by the aspherical mirror 11 can be incident on the reflecting member 21a.

[0013] The space communication light Lai incident at the first angle θ1 is reflected by the aspherical mirror 11 as the space communication light Lao in the direction along the optical axis C. The space communication light Lbi incident at the second angle θ2 is reflected by the aspherical mirror 11 as the space communication light Lbo in the direction along the optical axis C. The space communication light Li incident at the angle θ is reflected by the aspherical mirror 11 as the space communication light Lo in the direction along the optical axis C.

[0014] As shown in FIG. 1, as the angle θ increases from the angle θ1 to the angle θ2, the reflected space communication light Lo gradually changes its direction away from the optical axis C or from a direction parallel to the optical axis C toward the optical axis C. As a result, as will be described later, the position of the bright part on the image represented by the video data output from the image pickup device 22 changes for the space communication light Lo.

[0015] The aspherical mirror 11 has symmetry with respect to the optical axis C. That is, the reflection characteristics of the aspherical mirror 11 do not substantially depend on the angle (azimuth angle) φ representing the azimuth centered on the optical axis C. As a result, the aspherical mirror 11 can reflect the space communication light Li in the direction along the optical axis C and make it incident on the image pickup device 22 regardless of the value of the angle φ (that is, for all directions).

[0016] The space communication light Li incident on the aspherical mirror 11 and the space communication light L0 emitted from the aspherical mirror 11 are symmetric with respect to the normal line NV at the reflection point P on the aspherical mirror 11 (the law of light reflection). The angle θo of the space communication light Lo with respect to the optical axis C is determined by the elevation angle θ of the space communication light Li, the position of the reflection point P, and the curvature of the aspherical mirror 11. Therefore, the aspherical mirror 11 has a curvature corresponding to the viewing angle set in the elevation angle θ direction.

[0017] The aspherical mirror 11 can be defined by the shape of the three-dimensional curved surface (x(Φ,θ), y(Φ,θ), z(Φ,θ)) of its reflection surface. This three-dimensional curved surface can be appropriately selected according to the operation policy of the optical space communication device 1 and the like. (x, y, z): The x, y, and z coordinates of the point P on the reflection surface of the aspherical mirror 11 θ: The angle (elevation angle) formed by the normal line NV of the reflection surface with respect to the optical axis C at the point P Φ: The azimuth angle of the normal line NV of the reflection surface at the point P

[0018] Hereinafter, specific examples of the aspherical mirror 11 will be shown. FIG. 2 is a diagram showing an example of the aspherical mirror 11. Here, as an example of the aspherical mirror 11, aspherical mirrors 11a to 11c are shown.

[0019] The aspherical mirror 11a is composed of a convex surface 111. Since this aspherical mirror 11a has the convex surface 111, the range of the pointing direction with respect to the space communication light Li can be made relatively wide. This is because the convex surface 111 has a light diverging property that spreads light with respect to the condensing property of the concave surface 112 described later.

[0020] The aspherical mirror 11b is substantially composed of a concave surface 112. That is, although the aspherical mirror 11b includes a convex surface 111a, this convex surface 111a can be substantially ignored. This is because the convex surface 111a is limited to a range close to the optical axis C and does not contribute to the formation of the directional direction for the spatial communication light Li. Because the aspherical mirror 11b has a concave surface 112, the range of the directional direction for the spatial communication light Li can be made relatively narrow due to the light-gathering properties of the concave surface 112. As a result, it becomes easy to set the directional direction for the spatial communication light Li with relatively high precision.

[0021] Here, we will distinguish between convex and concave surfaces of the aspherical mirror 11 based on the sign of the radius of curvature of its reflective surface. A surface with a positive radius of curvature is considered convex, and a surface with a negative radius of curvature is considered concave. The symbol SP represents the plane passing through the inflection point (the boundary between the convex surface 111a and the concave surface 112) on the reflective surface of the aspherical mirror 11b. Similarly, the symbols SPa and SPb for the aspherical mirror 11c represent the planes passing through the inflection points (the boundary between the convex surface 111a and the concave surface 112b, and the boundary between the concave surface 112b and the convex surface 111b) on the reflective surface of the aspherical mirror 11c.

[0022] The aspherical mirror 11c is substantially composed of a combination of a concave surface 112b and a convex surface 111b. As previously described, the convex surface 111a can be substantially ignored. The aspherical mirror 11c has a relatively narrow range of directional direction for spatial communication light Li at the concave surface 112b, and a relatively wide range of directional direction for spatial communication light Li at the convex surface 111b. In other words, the aspherical mirror 11c has the characteristic of switching between a narrow directional range (narrow field of view) and a wide directional range (wide field of view) depending on whether the reflection point P of light on the reflective surface belongs to the concave surface 112b or the convex surface 111b.

[0023] Having the shape described above, the aspherical mirror 11 can reflect spatial communication light Li at an angle θ between angles θ1 and θ2 in a direction along the optical axis C. For angles θ1 and θ2, for example, they can be in the ranges of 2θ0 and 180°-2θ0, respectively. Here, θ0 represents the angle of spatial communication light Lo with respect to the optical axis C.

[0024] Here, it is assumed that the spatial communication light Li has a beam diameter that is sufficiently large relative to the aspherical mirror 11. If the beam diameter of the spatial communication light Li is small relative to the size of the aspherical mirror 11, the pattern of the spatial communication light Lo reflected by the aspherical mirror 11 will change depending on the position at which the spatial communication light Li is incident on the aspherical mirror 11. By making the beam diameter of the spatial communication light Li larger than the size of the aspherical mirror 11, it becomes possible to make the pattern of the reflected spatial communication light Lo dependent on the angles θ and Φ of the incident spatial communication light Li, and it becomes possible to determine the angles θ and Φ based on the image represented by the video data output from the image sensor 22.

[0025] The reflective member 21a reflects at least a portion of the spatial communication light Lin1 that has been reflected by the aspherical mirror 11 in a direction along the optical axis C.

[0026] The image sensor 22 receives the spatial communication light Lin1 reflected by the reflective member 21a and outputs image data that represents an image including bright areas corresponding to the spatial communication light Lo. In this image, the position of bright areas on the image data output from the image sensor 22 changes depending on the spatial communication light Lo.

[0027] (Effects of Optical Space Communication Device 1) As described above, the optical spatial communication device 1 receives spatial communication light Li incident on the optical axis C of the aspherical mirror 11 at an angle θ between a first angle θ1 and a second angle θ2, and can obtain image data including bright areas corresponding to this spatial communication light Li. The aspherical mirror 11 can receive spatial communication light Li at any azimuth angle with respect to the optical axis C, obtain image data including bright areas corresponding to this spatial communication light Li, and determine the angles θ and Φ of the spatial communication light Li.

[0028] [Second exemplary embodiment] A second exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. Components having the same function as those described in the above-described exemplary embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate. The scope of application of each technology adopted in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology adopted in this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical problems arise. Furthermore, each technology shown in the drawings referenced to describe this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical problems arise.

[0029] (Configuration of optical space communication device) The configuration of the optical spatial communication device 1A will be described with reference to Figure 3. As shown in Figure 3, the optical spatial communication device 1A comprises a housing 10, an aspherical mirror 11, a focusing optical unit 12, a field of view adjustment unit 13, a reflection mechanism 21, an image sensor 22, a light receiving unit 23, a light emitting unit 24, a reflection mirror M1, a spectral mirror M2, and a control unit 30. The housing 10 is composed of a lens barrel 14, a head unit 15, and a base unit 20.

[0030] The aspherical mirror 11, focusing optical unit 12, field of view adjustment unit 13, reflection mechanism 21, image sensor 22, and light receiving unit 23 are arranged in this order along the optical path of the incident spatial communication light L1. The aspherical mirror 11, focusing optical unit 12, and field of view adjustment unit 13 are arranged to be enclosed within the lens barrel 14. The reflection mechanism 21, image sensor 22, light receiving unit 23, light emitting unit 24, reflection mirror M1, and spectral mirror M2 are arranged to be enclosed within the base unit 20.

[0031] The spectral mirror M2 is positioned between the reflection mechanism 21 and the light receiving unit 23. The light-emitting unit 24 and the reflection mirror M1 are arranged in this order along the optical path of the spatial communication light L2 emitted from the light-emitting unit 24.

[0032] As described in the first exemplary embodiment, the aspherical mirror 11 is an aspherical mirror that reflects spatial communication light L1 incident at an angle greater than 0° with respect to the optical axis, such that the angle is greater than or equal to a first angle θ1 and less than or equal to a second angle θ2 less than 180°, in a direction along the optical axis. The incident range 16 indicates the incident range (field of view) of the spatial communication light L1.

[0033] As described in the first exemplary embodiment, the aspherical mirror 11 has rotational symmetry when the optical axis is the axis of rotation, and can receive spatial communication light L1 isotropically from all directions with respect to the azimuth angle φ within an angular range of θ1 to θ2 with respect to the optical axis. The lens barrel 14 is provided with an opening or transparent portion so that the spatial communication light L1 can be incident on the aspherical mirror 11 isotropically from all directions with respect to the azimuth angle φ within an angular range of θ1 to θ2 with respect to the optical axis C of the aspherical mirror 11. In other words, the lens barrel 14 has an omnidirectional opening window that is open in all directions.

[0034] The reflection mechanism 21 consists of a reflective member 21a that reflects at least a portion of the spatial communication light L1 reflected by the aspherical mirror 11 in a direction along the optical axis, and an angle change mechanism 21b that changes the angle of the reflective member 21a. The angle change mechanism 21b is capable of independently rotating the reflective member 21a with respect to two different first and second axes. The angle change mechanism 21b is controlled by the control unit 30 so that the spatial communication light L1 is incident perpendicularly on the image sensor 22.

[0035] The image sensor 22 receives the spatial communication light L1 reflected by the reflective member 21a and outputs image data including the bright area corresponding to the spatial communication light L1.

[0036] Figure 4 shows an example of an image 40 represented by video data output from the image sensor 22. As shown in Figure 4, the image 40 includes bright areas corresponding to spatial communication light. In this specific example, the region on the image 40 corresponding to the bright area corresponding to the spatial communication light L1 is defined as the bright area region 41.

[0037] Image 40 includes a bright region 41 corresponding to a bright area and a dark region 42 corresponding to the optical axis C. The bright region 41 includes a central area 43 located between a first closed curve C1 surrounding the dark region 42 and a second closed curve C2 surrounding the first closed curve C1. The first closed curve C1 corresponds to spatial communication light incident on the optical axis C at a first angle θ1, and the second closed curve C2 corresponds to spatial communication light incident on the optical axis C at a second angle θ2.

[0038] In other words, the closed curve C is the distance r(θ) from the center point O of the dark region 42. i The central part 43 of the bright area 41 is located above. In this example, r(θ) = aθ. From this, the elevation angle θ can be derived from the position of the central part 43.

[0039] Furthermore, by pre-adjusting the reference line so that the angle between the line connecting the center point O and the central point 43, with respect to the reference line passing through the center point O, is equal to the azimuth angle φ, the azimuth angle φ can be derived from the position of the central point 43.

[0040] The parameter (a) of r(θ) and the position of the reference line can be adjusted according to the inclination of the reflective member 21a.

[0041] The focusing optical unit 12 consists of a convex lens 12a and a focusing adjustment mechanism 12b. The focusing adjustment mechanism 12b adjusts the degree of convergence of the spatial communication light L1 reflected by the aspherical mirror 11 by moving the convex lens 12a in the Y-axis direction (optical axis C direction). This allows the spatial communication light L1 received by the convex lens 12a to be focused onto the reflecting member 21a.

[0042] The field of view adjustment unit 13 consists of a concave lens 13a and a field of view adjustment mechanism 13b. The field of view adjustment mechanism 13b can move the concave lens 13a in the XY direction, either to a position where the concave lens 13a does not receive spatial communication light L1, or to a position where the concave lens 13a receives spatial communication light L1. By moving the concave lens 13a to a position where it receives spatial communication light L1, image data including the enlarged bright area can be output to the image sensor 22.

[0043] Figure 3 shows the field of view adjustment mechanism 13b in a position where the concave lens 13a is not receiving the spatial communication light L1. Figure 5 shows the field of view adjustment mechanism 13b in a position where the concave lens 13a is receiving the spatial communication light L1.

[0044] As shown in Figure 5, the field of view adjustment mechanism 13b moves the concave lens 13a to a position where it receives the spatial communication light L1, thereby narrowing the incident range 16 (field of view) of the spatial communication light L1 incident on the reflective member 21a. In this way, the field of view adjustment mechanism 13b allows control over whether to prioritize a wide field of view or a narrow field of view for long-distance communication.

[0045] The light receiving unit 23 is a means for receiving spatial communication light L1 reflected by the reflective member 21a whose angle has been changed by the angle changing mechanism 21b.

[0046] The light-emitting unit 24 is a means for emitting the second optical communication light L2. The second optical communication light L2 emitted from the light-emitting unit 24 is reflected by the reflective mirror M1 and incident on the reflective member 21a whose angle has been changed by the angle-changing mechanism 21b.

[0047] The reflective mirror M1 is a means for reflecting the second optical communication light L2 emitted from the light-emitting unit 24. The second optical communication light L2 reflected by the reflective mirror M1 is incident on the reflective member 21a, whose angle has been changed by the angle-changing mechanism 21b, and is reflected by the reflective member 21a in the same direction as the optical path of the spatial communication light L1.

[0048] The spectral mirror M2 is a means of spectrally analyzing the spatial communication light L1, which has been reflected by the reflective member 21a, by transmitting it to the light receiving unit 23 and reflecting it back to the image sensor 22, thereby causing the spatial communication light L1 to be incident on the light receiving unit 23 and the image sensor 22.

[0049] The control unit 30 controls the angle change mechanism 21b based on an image including a bright area corresponding to the spatial communication light L1. More specifically, the control unit 30 is a means for performing a determination process to determine the incident angle and incident direction of the spatial communication light L1 with respect to the optical axis C based on image data output by the image sensor 22, and an angle control process to control the angle change mechanism 21b based on the incident angle and incident direction of the spatial communication light L1 determined in the determination process.

[0050] A portion of the image 40 shown in Figure 4 (region Rx) corresponds to the light-receiving range of the light-receiving unit 23. In other words, in image 40, the bright region 41 overlaps with region Rx, causing the spatial communication light L1 to enter the light-receiving range of the light-receiving unit 23. The control unit 30 controls the angle change mechanism 21b so that the position of the center 43 of the bright region 41 in image 40 corresponds to region Rx (so that the bright region 41 and region Rx overlap or coincide), thereby causing the spatial communication light L1 to enter the light-receiving range of the light-receiving unit 23 and achieving good reception.

[0051] In other words, the image sensor 22 has a larger field of view than the light receiving unit 23, and is capable of searching for and detecting light from the target station for coarse tracking, thus functioning as a coarse tracking image sensor. Furthermore, by controlling the angle change mechanism 21b so that the position of the center 43 of the bright area 41 in the image 40 corresponds to the area Rx, the image sensor 22 also functions as a high-precision tracking image sensor.

[0052] Details of the control unit 30 will be explained with reference to Figure 6. Figure 6 is an overall configuration diagram of the control unit 30 and housing unit 10 of the optical space communication device 1A. Some components of the housing unit 10 are omitted in the diagram. As shown in Figure 6, the control unit 30 consists of a coordinating controller 31, a target position estimater 32, and a tracking controller 33.

[0053] The target position estimator 32 performs a determination process to determine the incident angle and incident direction of the spatial communication light L1 relative to the optical axis C based on the image data output by the image sensor 22, and generates a target angle based on the incident angle and incident direction of the spatial communication light L1 determined in the determination process. In addition to the target angle, a target angular velocity may also be generated. The coordinating controller 31 provides the target angle (and target angular velocity) generated by the target position estimator 32 to the tracking controller 33. The tracking controller 33 controls the angle change mechanism 21b based on the target angle (and target angular velocity) generated by the target position estimator 32, thereby performing an angle control process to control the angle change mechanism 21b based on the incident angle and incident direction of the spatial communication light L1 determined in the determination process. The tracking controller 33 may control the angle change mechanism 21b by inputting a control signal to the head unit 15.

[0054] Furthermore, the tracking control performed by the control unit 30 may involve first performing coarse tracking control to make rough angle adjustments, followed by fine tracking control to make finer angle adjustments. In coarse tracking control, the coordinating controller 31 may control the field of view adjustment unit 13 and the focusing optical unit 12 as needed. In fine tracking control, the target position estimater 32 may generate the target angle not only based on the image data output by the image sensor 22, but also based on the output of the light receiving unit 23.

[0055] With the above configuration, the spatial communication light L1 reflected by the aspherical mirror 11 can be received well in the light-receiving area of ​​the light-receiving unit 23. This enables good optical spatial communication. Furthermore, the spatial communication light L2 (second optical communication light) emitted from the light-emitting unit 24 enters the aspherical mirror 11 via a predetermined optical system, along the path of the spatial communication light L1 reflected by the aspherical mirror 11, and is reflected by the aspherical mirror 11 along the path of the spatial communication light L1 entering the aspherical mirror 11. This enables accurate transmission of the spatial communication light to the receiving station that emitted the spatial communication light L1.

[0056] (Flowchart of the control method for optical space communication devices) The flow of control method S1 for the optical space communication device 1A will be explained with reference to Figure 7.

[0057] First, let's explain how to set the direction of optical spatial communication. As shown in Figure 1, the optical spatial communication device 1 performs optical spatial communication with the communication target T, which is another optical spatial communication device, using spatial communication light.

[0058] In this case, the light vector can be defined as follows. Light vector Li: The vector of spatial communication light traveling from the communication target T to the optical spatial communication device 1A (aspherical mirror 11). Light vector Lo: The vector of spatial communication light traveling from the aspherical mirror 11 to the reflecting member 21a. Light vector Los: The vector of spatial communication light traveling from the reflective member 21a to the image sensor 22.

[0059] The coordinates of the communication target T and the coordinates of the reflection point P on the aspherical mirror 11 are expressed as follows: T=(xt,yt,zt) P=(xp,yp,zp)

[0060] Furthermore, the normal vector can be defined as follows: Normal vector NV11 (=(a11,b11,c11)): The vector of the normal NV on the reflective surface of the aspherical mirror 11. Normal vector NV21: The normal vector on the reflective surface of the reflective member 21a.

[0061] At this time, the target angle (ψ,θ) of the communication target T as seen from the optical space communication device 1 can be expressed by the following equation. ψ = atan[(yp-yt) / (xp-xt)] θ = atan[(zp-zt) / ((xp-xt)] 2 +(yp-yt) 2 ) 1 / 2 ]

[0062] The following equation holds true from the light reflection model. Lo - (-Li) = (NV11 / (-Li)) · NV11 Loss - (-L0) = (NV12 / (-L0)) · NV12

[0063] The relationship between the normal vector NV21(a21,b21,c21) of the reflective member 21a and the angle (X,Y) of the reflective member 21a along its two axes is expressed by the following equation. X = asin(a21) Y = atan(b²¹ / c²¹) - π / 4

[0064] The relationship between the normal vector NV11 on the aspherical mirror 11 and the reflection point P can be expressed in polar coordinates on the aspherical mirror 11 with reference point (0,0,0) as follows: P(x(ψ,θ),y(ψ,θ),z(ψ,θ)) θ: The angle (elevation angle) that the perpendicular NV of the reflective surface makes with the optical axis C at the reflection point P. Φ: Azimuth angle of the perpendicular NV to the reflective surface at reflection point P.

[0065] Here, if we know the angle (ψ,θ) between the reflection point P and the normal vector NV11, we can derive the normal vector NV11. The angle (ψ,θ) can be derived from the angle (X,Y) of the driving mirror that forms the light vector Lo.

[0066] Furthermore, since the three-dimensional shape of the reflective surface of the aspherical mirror 11 is fixed, the relationship between the reflection point P and the light vector L0 can be determined with respect to the direction of direction toward the communication target T, and the angle (X,Y) of the reflective member 21a can be set. In this way, it becomes possible to direct spatial communication light toward the communication target T in an appropriate direction.

[0067] Figure 7 is a flowchart showing the flow of the control method S1 for the optical spatial communication device 1A. As shown in Figure 7, the control method S1 for the optical spatial communication device 1A includes image data acquisition processing S2, narrow field adjustment necessity processing S3, field angle adjustment processing S4, focus adjustment necessity processing S5, focus adjustment processing S6, target value calculation processing S7, and tracking control processing S8.

[0068] Image data acquisition process S2 is a process in which the control unit 30 (specifically the target position estimater 32) acquires image data from the image sensor 22 that includes the bright portion of the spatial communication light L1 reflected by the aspherical mirror 11 in a direction along the optical axis C.

[0069] The narrow field adjustment necessity process S3 is a process that determines whether or not control of the field angle adjustment unit 13 is necessary because the light for spatial communication, which is incident on the optical axis C at an angle of a first angle θ1 or more and a second angle θ2 or less, is magnified by the aspherical mirror 11 in a direction along the optical axis C.

[0070] The narrow field adjustment process S3 is a process for determining whether or not adjustment of the field of view is necessary.

[0071] For example, if the optical spatial communication device 1 has not found the other station, it is necessary to search for the other station in a wide field of view. In this case, it is preferable for the optical spatial communication device 1 (and the optical spatial communication device of the other station) to emit spatial communication light L2 with a wide beam diameter and receive spatial communication light L1 with a wide beam diameter from the other station (optical communication in a wide field of view). This makes it easier for the optical spatial communication device 1 to receive spatial communication light L1 from the other station.

[0072] On the other hand, if the optical spatial communication device 1 has located the other station, searching in a wide field of view becomes unnecessary, and it is preferable to narrow the beam diameter of the spatial communication light L1 and L2 to some extent and increase the intensity of the spatial communication light L1 received by the light receiving unit 23 (optical communication in a narrow field of view). This makes stable optical communication easier.

[0073] The light-emitting unit 24 may have an adjustment mechanism to adjust the width of the beam diameter of the spatial communication light L2. The light-emitting unit 24 is controlled by the field of view adjustment unit 13 to adjust the width of the beam diameter.

[0074] For example, if the image data output by the image sensor 22 does not include any bright areas of the spatial communication light L1, the control unit 30 (specifically its target position estimater 32) may determine that it has not detected the other station and therefore needs to widen the beam diameter of the spatial communication light L2. This determination is also made by the other station's optical spatial communication device 1p, and as a result, the optical spatial communication device 1 can easily receive the spatial communication light L1 from the other station's optical spatial communication device 1p.

[0075] Furthermore, for example, if the image data output by the image sensor 22 includes a bright area of ​​spatial communication light L1 near the center of the image, but the brightness of the bright area is low, the control unit 30 (specifically, its target position estimater 32) may determine that it is necessary to narrow the beam diameter of the spatial communication light L2. This determination is also made at the other station's optical spatial communication device 1p, and as a result, the optical spatial communication device 1 can receive higher intensity spatial communication light L1 from the other station's optical spatial communication device 1p.

[0076] In the narrow field adjustment necessity processing S3, if it is determined that control of the field of view adjustment unit 13 is necessary, the control unit 30 (or its coordinating controller 31) controls the field of view adjustment unit 13 in the field of view adjustment processing S4. As a result, the beam diameter of the spatial communication light L2 is adjusted. At this time, the control unit 30 (or its coordinating controller 31) may control the field of view adjustment unit 13 via the head unit 15.

[0077] The focus adjustment necessity process S5 is a process that determines whether or not control of the focusing optical unit 12 is necessary in order to focus the light for spatial communication, which is incident on the optical axis C at an angle of a first angle θ1 or more and a second angle θ2 or less, reflected by the aspherical mirror 11 in a direction along the optical axis C, onto the reflecting member 21a.

[0078] For example, if the field of view adjustment process S4 is performed, or if the bright areas of the image shown in the image data output by the image sensor 22 are blurred, the control unit 30 (specifically, its target position estimater 32) may determine that focus adjustment is necessary.

[0079] If, in the focus adjustment necessity processing S5, it is determined that control of the converging optical unit 12 is necessary, then in the focus adjustment processing S6, the control unit 30 (or its coordinating controller 31) controls the converging optical unit 12. At this time, the control unit 30 (or its coordinating controller 31) may control the converging optical unit 12 via the head unit 15.

[0080] In the target value calculation process S7, the control unit 30 (specifically, its target position estimator 32) determines the angle (θ, φ) of the light for spatial communication incident on the aspherical mirror with respect to the optical axis C, based on the pixel coordinates of the central part 43 of the bright area 41 included in the image obtained by the image data acquisition process S2 (determination process).

[0081] As described above, the elevation angle θ can be derived based on the distance from the center point O of the dark region 42 corresponding to the optical axis C. Furthermore, the azimuth angle φ can be derived based on the angle of the line connecting the center point O and the central region 43 with respect to a reference line passing through the center point O.

[0082] Then, the control unit 30 (specifically the target position estimator 32) calculates a target angle for the reflective member 21a based on the angle (θ, φ) at which the spatial communication light L1 is incident, so that the spatial communication light L1 reflected by the aspherical mirror 11 and then reflected by the reflective member 21a reaches the light-receiving area of ​​the light-receiving unit 23. From another perspective, the control unit 30 (specifically the target position estimator 32) calculates a target angle for the reflective member 21a such that the position of the center 43 of the bright area 41 in the image 40 corresponds to area Rx.

[0083] Then, in the tracking control process S8, the control unit 30 (specifically the tracking controller 33) controls the angle change mechanism 21b based on the target value calculated in the target value calculation process S7. At this time, the control unit 30 (specifically the tracking controller 33) may also control the angle change mechanism 21b via the head unit 15.

[0084] Furthermore, in tracking control processing S8, the control unit 30 (specifically the tracking controller 33) may perform precise tracking control. In precise tracking control, the control unit 30 (specifically the tracking controller 33) may control the angle change mechanism 21b based not only on the image data output by the image sensor 22, but also on the target value generated by the control unit 30 (specifically the target position estimater 32) based on the signal from the light receiving unit 23.

[0085] Based on the above, by eliminating the coarse tracking drive mechanism, such as a gimbal, which is one of the complex components that make up conventional optical spatial communication devices, it becomes possible to eliminate factors that cause optical axis alignment errors, and by eliminating the gimbal, which accounts for a large proportion of the total mass, it becomes possible to make the device smaller and lighter, improving operability such as mounting on drones. In addition, by eliminating the components of the drive system, it also contributes to reducing the probability of failure.

[0086] [Third Exemplary Embodiment] A third exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. Components having the same function as those described in the above-described exemplary embodiments are denoted by the same reference numerals, and their descriptions are omitted as appropriate. The scope of application of each technology adopted in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology adopted in this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical hindrance occurs. Furthermore, each technology shown in the drawings referenced to describe this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical hindrance occurs.

[0087] (Configuration of optical space communication device) The configuration of the optical space communication device 1B will be explained with reference to Figure 8. The optical space communication device 1B is equipped with an optical unit 71a and an angle change mechanism 71b in place of the reflection mechanism 21 in the optical space communication device 1A.

[0088] The optical unit 71a includes at least an image sensor 22 and a light-receiving unit 23, and may also include a light-emitting unit 24, a reflective mirror M1, and a spectral mirror M2 (reflective member). The angle change mechanism 71b is composed of a gimbal or the like and is a means for tilting the optical unit 71a.

[0089] The angle-changing mechanism 71b tilts the optical unit 71a, thereby changing the angle of the spectral mirror M2 (reflective member) with respect to the optical axis C. This allows the angle at which the spatial communication light L1 is incident on the image sensor 22 and the light-receiving unit 23 to be adjusted, and thus the angle-changing mechanism 71b has the same function as the angle-changing mechanism 21b. Therefore, by the control unit 30 controlling the angle-changing mechanism 71b instead of the angle-changing mechanism 21b, the optical spatial communication device 1B can achieve the same function as the optical spatial communication device 1A.

[0090] [Fourth exemplary embodiment] A fourth exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. Components having the same function as those described in the above-described exemplary embodiments are denoted by the same reference numerals, and their descriptions are omitted as appropriate. The scope of application of each technology adopted in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology adopted in this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical hindrance occurs. Furthermore, each technology shown in the drawings referenced to describe this exemplary embodiment can also be adopted in other exemplary embodiments included in this disclosure, to the extent that no particular technical hindrance occurs.

[0091] (Configuration of Optical Space Communication Device 1C) The configuration of the optical space communication device 1C will be explained with reference to Figure 9. The optical space communication device 1C has a configuration in which the optical space communication device 1A (or optical space communication device 1B) is coupled with the head units 15 facing each other, and the control unit 30 is shared. By configuring it in this way, the incident range 16 can be extended in the direction of the optical axis, and an optical space communication device capable of optical space communication in all directions can be realized.

[0092] (Modified version of optical space communication device 1) In the above configuration, the optical spatial communication device 1 has one reflection mechanism 21, an image sensor 22, a light receiving unit 23, and a light emitting unit 24 for each aspherical mirror 11, enabling communication with one communication target. In contrast, the optical spatial communication device 1 may have multiple reflection mechanisms 21, image sensors 22, light receiving units 23, and light emitting units 24 for each aspherical mirror 11. By doing so, the optical spatial communication device 1 can direct multiple spatial communication beams (multibeams) in different directions from each other, enabling optical spatial communication with multiple communication targets T.

[0093] [Examples of implementation using software] The functions of some or all of the control units 30 of the optical space communication devices 1, 1A, 1B, and 1C (hereinafter also referred to as "each of the above devices") may be implemented by hardware such as integrated circuits (IC chips) or by software.

[0094] In the latter case, the control unit (control unit 30) of each of the above devices is implemented, for example, by a computer that executes instructions for a program, which is software that realizes each function. An example of such a computer (hereinafter referred to as computer C) is shown in Figure 10. Figure 10 is a block diagram showing the hardware configuration of computer C, which functions as the control unit of each of the above devices.

[0095] Computer C comprises at least one processor C1 and at least one memory C2. Memory C2 stores a program P that causes computer C to operate as the control unit for each of the above-mentioned devices. In computer C, the processor C1 reads program P from memory C2 and executes it, thereby realizing each of the above-mentioned devices.

[0096] For processor C1, for example, a CPU (Central Processing Unit), GPU (Graphic Processing Unit), DSP (Digital Signal Processor), MPU (Micro Processing Unit), FPU (Floating Point Number Processing Unit), PPU (Physics Processing Unit), TPU (Tensor Processing Unit), quantum processor, microcontroller, or a combination thereof can be used. For memory C2, for example, flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof can be used.

[0097] Computer C may also be equipped with RAM (Random Access Memory) for loading program P at runtime and for temporarily storing various data. Furthermore, computer C may be equipped with communication interfaces for sending and receiving data with other devices. Additionally, computer C may be equipped with input / output interfaces for connecting input / output devices such as keyboards, mice, displays, and printers.

[0098] Furthermore, program P can be recorded on a non-temporary, tangible recording medium M that is readable by computer C. Such a recording medium M could be, for example, tape, disk, card, semiconductor memory, or programmable logic circuitry. Computer C can acquire program P via such a recording medium M. Program P can also be transmitted via a transmission medium. Such a transmission medium could be, for example, a communication network or broadcast waves. Computer C can also acquire program P via such a transmission medium.

[0099] Furthermore, each of the above functions of each of the above devices may be implemented by a single processor in a single computer, by multiple processors in a single computer working together, or by multiple processors in each of multiple computers working together. In addition, the programs for implementing each of the above functions in each of the above devices may be stored in a single memory in a single computer, distributed and stored in multiple memories in a single computer, or distributed and stored in multiple memories in each of multiple computers.

[0100] [Additional Note 1] This disclosure includes the technologies described in the following appendices. However, the present invention is not limited to the technologies described in the following appendices, and various modifications are possible within the scope of the claims.

[0101] (Note 1) An optical spatial communication device comprising: an aspherical mirror having an optical axis and reflecting spatial communication light incident on the optical axis at an angle greater than a first angle greater than 0° and less than a second angle less than 180° in a direction along the optical axis; a reflective member that reflects at least a portion of the spatial communication light reflected by the aspherical mirror in a direction along the optical axis; and an image sensor that receives the spatial communication light reflected by the reflective member and outputs image data representing an image including bright areas corresponding to the spatial communication light.

[0102] (Note 2) The optical space communication device according to Appendix 1, comprising: an angle-changing mechanism for changing the angle of the reflective member; and a control unit for controlling the angle-changing mechanism based on the image.

[0103] (Note 3) The optical space communication device as described in Appendix 2, wherein the image includes a dark area corresponding to the optical axis, the bright area includes a central part located between a first closed curve surrounding the dark area and a second closed curve surrounding the first closed curve, the first closed curve corresponds to spatial communication light incident on the optical axis at a first angle, and the second closed curve corresponds to spatial communication light incident on the optical axis at a second angle.

[0104] (Note 4) The optical spatial communication device as described in Appendix 3, wherein the control unit performs a determination process to determine the incident angle and incident direction of the spatial communication light with respect to the optical axis based on the position of the central part on the image, and an angle control process to control the angle change mechanism based on the incident angle and incident direction of the spatial communication light determined in the determination process.

[0105] (Note 5) An optical spatial communication device according to Appendix 3 or 4, comprising a light-receiving unit that receives spatial communication light reflected by the reflective member, wherein the light-receiving range of the light-receiving unit corresponds to a part of the image, and the control unit controls the angle change mechanism so that the position of the center in the image corresponds to the part of the image.

[0106] (Note 6) An optical space communication device according to Appendix 1 or 2, comprising a light-emitting unit that emits a second optical communication light, wherein the second optical communication light emitted from the light-emitting unit is incident on the aspherical mirror via a predetermined optical system, along with the optical communication light reflected by the aspherical mirror, and is reflected by the aspherical mirror along with the optical communication light incident on the aspherical mirror.

[0107] (Note 7) The optical spatial communication device according to Appendix 1 or 2, further comprising a convergence adjustment mechanism for adjusting the degree of convergence of spatial communication light reflected by the aspherical mirror.

[0108] (Note 8) The optical space communication device according to Appendix 5, comprising an optical unit on which the image sensor and the light receiving unit are arranged, wherein the angle change mechanism changes the angle of the reflective member with respect to the optical axis by tilting the optical unit.

[0109] (Note 9) A control method for an optical space communication device as described in Appendix 1, wherein the optical space communication device includes an angle change mechanism for changing the angle of the reflective member, and the control method controls the angle change mechanism based on image data output from the image sensor.

[0110] (Note 10) A program to cause a computer to execute the control method for the optical space communication device described in Appendix 9.

[0111] [Additional Note 2] This disclosure includes the technologies described in the following appendices. However, the present invention is not limited to the technologies described in the following appendices, and various modifications are possible within the scope of the claims.

[0112] (Note 1) An optical spatial communication device comprising: an aspherical mirror having an optical axis and reflecting spatial communication light incident on the optical axis at an angle greater than a first angle greater than 0° and less than a second angle less than 180° in a direction along the optical axis; a reflective member that reflects at least a portion of the spatial communication light reflected by the aspherical mirror in a direction along the optical axis; and an image sensor that receives the spatial communication light reflected by the reflective member and outputs image data representing an image including bright areas corresponding to the spatial communication light.

[0113] (Note 2) The optical space communication device according to Appendix 1, comprising: an angle-changing mechanism for changing the angle of the reflective member; and at least one processor for controlling the angle-changing mechanism based on the image.

[0114] (Note 3) The optical space communication device as described in Appendix 2, wherein the image includes a dark area corresponding to the optical axis, the bright area includes a central part located between a first closed curve surrounding the dark area and a second closed curve surrounding the first closed curve, the first closed curve corresponds to spatial communication light incident on the optical axis at a first angle, and the second closed curve corresponds to spatial communication light incident on the optical axis at a second angle.

[0115] (Note 4) The optical spatial communication device according to Appendix 3, wherein the at least one processor performs a determination process to determine the incident angle and incident direction of the spatial communication light with respect to the optical axis based on the position of the central part on the image, and an angle control process to control the angle change mechanism based on the incident angle and incident direction of the spatial communication light determined in the determination process.

[0116] (Note 5) The optical spatial communication device according to Appendix 3 or 4, comprising a light-receiving unit that receives spatial communication light reflected by the reflective member, wherein the light-receiving range of the light-receiving unit corresponds to a portion of the image, and at least one processor controls the angle-changing mechanism such that the position of the central part in the image corresponds to the portion of the image.

[0117] (Note 6) An optical space communication device according to Appendix 1 or 2, comprising a light-emitting unit that emits a second optical communication light, wherein the second optical communication light emitted from the light-emitting unit is incident on the aspherical mirror via a predetermined optical system, along with the optical communication light reflected by the aspherical mirror, and is reflected by the aspherical mirror along with the optical communication light incident on the aspherical mirror.

[0118] (Note 7) The optical spatial communication device according to Appendix 1 or 2, further comprising a convergence adjustment mechanism for adjusting the degree of convergence of spatial communication light reflected by the aspherical mirror.

[0119] (Note 8) The optical space communication device according to Appendix 5, comprising an optical unit on which the image sensor and the light receiving unit are arranged, wherein the angle change mechanism changes the angle of the reflective member with respect to the optical axis by tilting the optical unit.

[0120] The optical space communication device may also include a memory. Furthermore, the memory may store a program that causes at least one processor to perform each of the aforementioned processes. [Explanation of symbols]

[0121] 1, 1A, 1B, 1C...Optical space communication equipment 10 ···Housing 11...Aspherical mirror 12 ···Converging Optical Section 12b ···Convergence adjustment mechanism 13...Viewing angle adjustment section 14. Telescope tube section 15 ···Head section 20 ···Base section 21...reflection mechanism 21a ···Reflective material 21b ···Angle change mechanism 22 ···Image sensor 23...Light receiving section 24 ···Light-emitting part M1 ···Reflective mirror M2 ···Spectroscopic mirror 30 ···Control Unit 71a ···Optical Unit 71b ···Angle change mechanism

Claims

1. An aspherical mirror having an optical axis, which reflects spatial communication light incident on the optical axis at an angle greater than a first angle greater than 0° and less than a second angle less than 180°, in a direction along the optical axis, A reflective member that reflects at least a portion of the spatial communication light reflected in the direction along the optical axis by the aspherical mirror, An image sensor that receives spatial communication light reflected by the reflective member and outputs image data representing an image including bright areas corresponding to the spatial communication light, An optical space communication device equipped with the following features.

2. An angle-changing mechanism for changing the angle of the reflective member, The system comprises a control unit that controls the angle change mechanism based on the aforementioned image, The optical space communication device according to claim 1.

3. The aforementioned image includes a dark area corresponding to the optical axis, The bright area includes a central part located between a first closed curve surrounding the dark area and a second closed curve surrounding the first closed curve. The first closed curve corresponds to spatial communication light incident at the first angle with respect to the optical axis, The second closed curve corresponds to the spatial communication light incident on the optical axis at the second angle, The optical space communication device according to claim 2.

4. The control unit, A determination process is performed to determine the incident angle and incident direction of the spatial communication light relative to the optical axis, based on the position of the central part on the aforementioned image. An angle control process is performed to control the angle change mechanism based on the incident angle and incident direction of the spatial communication light determined in the determination process. The optical space communication device according to claim 3.

5. The system includes a light-receiving unit that receives spatial communication light reflected by the reflective member, The light-receiving range of the light-receiving unit corresponds to a portion of the image, The control unit controls the angle change mechanism so that the position of the central part in the image corresponds to the partial region. The optical space communication device according to claim 3 or 4.

6. It includes a light-emitting unit that emits a second optical communication light, The second optical communication light emitted from the light-emitting unit enters the aspherical mirror via a predetermined optical system, along the optical communication light reflected by the aspherical mirror, and is reflected by the aspherical mirror in a manner that follows the optical communication light entering the aspherical mirror. The optical space communication device according to claim 1 or 2.

7. It includes a convergence adjustment mechanism that adjusts the degree of convergence of the spatial communication light reflected by the aspherical mirror. The optical space communication device according to claim 1 or 2.

8. The optical unit comprises the image sensor and the light-receiving unit, The angle-changing mechanism changes the angle of the reflective member with respect to the optical axis by tilting the optical unit. The optical space communication device according to claim 5.

9. A control method for an optical space communication device according to claim 1, The optical space communication device includes an angle change mechanism for changing the angle of the reflective member, The control method described above is Based on the image data output from the image sensor, the angle change mechanism is controlled. A control method for optical space communication devices.

10. A program for causing a computer to execute the control method for the optical space communication device described in claim 9.

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