JP2005252842A - Optical axis control apparatus and optical communications equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dynamically change the optical axis of an optical signal and in a short time. <P>SOLUTION: A reflection unit D11 can arbitrarily change the angle of a reflector plate, disposed on the axis of an optical signal to orient the reflected light axis of an reflected signal in an arbitrary direction. In a storage unit D14, angle information for orienting the reflected light axis to a targeted direction is previously stored. A monitor unit D15 monitors whether optical communication is in proper conditions; and if the optical communication has been suspended, it instructs a calculation unit 13 to change the optical axis. The calculation unit 13, upon receipt of the optical axis change instruction from the monitor unit D15, reads angle information, corresponding to the target angle from the storage unit D14, to obtain a rotation angle from the difference of the reflector plate from the current angle, and obtains a drive voltage value, corresponding to the rotation angle for providing to a drive unit D12. The drive unit D12 rotates and drives a motor mounted to the rotating axis of the reflector plate by a given drive voltage, thus enabling the optical axis of the optical signal to be shifted in the previously targeted direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical axis control device that is used in an optical space communication device and changes an optical axis of an optical signal.

In the conventional optical space communication system, as shown in FIG. 1, the optical axes of the optical transmission lines connecting the first optical space communication device A and the second optical space communication device B are made to coincide with each other. Thereafter, the optical axis is fixed at the pan angle θ _PA and tilt angle θ _TA of the first optical space communication device A and the pan angle θ _PB and tilt angle θ _TB of the second space communication device B in this state. The first optical space communication device A includes an optical transmitter A1 and an optical receiver A2, and similarly, the second optical space communication device B includes an optical transmitter B1 and an optical receiver B2, and between the transceivers. Correspondingly, the optical signals P1, P2 can be transmitted and received. In this state, the first optical space communication device A is connected to the first network N1, and the second optical space communication device B is connected to the second network N2. One-to-one communication between the first and second networks is enabled by optical space communication between the communication devices A and B.

However, with the pan angle θ _PA and tilt angle θ _{TA of} the first optical space communication device A and the pan angle θ _PB and tilt angle θ _{TB of} the second optical space communication device B fixed, the first light If the space communication device A and the second space optical communication device B are shielded by a shielding object, the optical signals P1 and P2 are both blocked, and communication becomes impossible.

Hereafter, the prior art relevant to this invention is illustrated.
First, Patent Document 1 discloses an “optical space transmission device” having a function of controlling an optical axis with two drive systems that can move a finder field of view and an optical system direction.
Patent Document 2 discloses an “automatic tracking optical communication device” that scans in a spiral manner and tracks a receiver mounted on an aircraft by rotating two mirrors whose rotation axes are orthogonal to each other. Yes.

Patent Document 3 discloses a “bidirectional spatial optical communication device” that corrects the beam center position at its own station using a beam splitter and a movable mirror optical system.
Patent Document 4 discloses an “optical space transmission device” that performs initial setting of a transmission destination scene and a beam point image using a camera finder and automatic alignment by a servo operation.

Further, Patent Document 5 discloses a “optical wireless transmission / reception device, optical wireless device, and optical device that uses a parabolic reflector to prevent interference between multiple channels and facilitates optical axis alignment with a wide directional light emitter / receiver. An optical axis adjustment method for a wireless device is disclosed.
In Patent Document 6, the pilot signal is superimposed on the main signal light, and the beam direction according to the transmission distance is controlled by controlling the emission direction, and at the same time, the pilot signal level is controlled to automatically adjust the optical axis (initially viewing). An “optical space communication device” that performs a semi-scope is disclosed.

Patent Document 7 discloses an “optical space communication device” that detects a change in the attitude of its own station using a light receiving position sensor or an acceleration sensor, and performs axis deviation correction driving using a variable apex angle prism.
In Non-Patent Document 1, as an “optical path switching technology using an anti-elbow mirror”, an “optical path switching device” using an optical axis control device is actually constructed in combination with an optical space communication device, and transmitted light is transmitted. A report relating to the result of an optical axis switching experiment in which the time required for switching is measured is disclosed.

Non-Patent Document 2 describes, as "the latest information on outdoor space optical transmission technology", the outline of the optical axis fine adjustment function used in the conventional optical space communication device and the influence of the weather as the reason why the function is necessary. A report on the difficulty of predicting transmission loss is disclosed.
Further, Non-Patent Document 3 discloses an “automatic tracking function” for automatically aligning the optical axis with the center of the diameter as an outline of a commercially available optical space communication device.

Japanese Patent Laid-Open No. 02-137531 “Optical Space Transmission Device”

Japanese Patent Laid-Open No. 03-200090 “Automatic Tracking Optical Communication Device”

Japanese Patent Laid-Open No. 05-133716 “Bidirectional Spatial Optical Communication Device”

Japanese Patent Laid-Open No. 05-227100 “Optical Space Transmission Device”

Japanese Patent Laid-Open No. 06-224858 “Optical Wireless Transmitting / Receiving Device, Optical Wireless Device, and Optical Axis Adjustment Method for Optical Wireless Device”

Japanese Patent Application Laid-Open No. 07-143064 "Optical Space Communication Device"

Japanese Patent Application Laid-Open No. 07-175021 “Optical Space Communication Device”

Paper to be presented at the 2004 IEICE General Conference "Optical path switching technology using an anti-elbow mirror"

On the optical wireless communication system promotion council homepage (http://www.icsa.gr.jp/library/index.htm), "Latest information on outdoor space optical transmission technology" (PDF) (p2-p12)

Canon Inc. website (http://cweb.canon.jp/indtech/canobeam/index.html), CANOBEAM catalog (PDF)

  As described above, in the conventional optical space communication device, if an object enters between the other side optical space communication devices, the optical signal is blocked and communication is no longer possible. Therefore, multiple counterpart devices can be prepared in positions where the optical axes are different from each other in advance, and when an obstruction enters the optical transmission path in communication, communication can be resumed by switching the optical transmission path to another counterpart device. It is considered that. In this case, in the optical space communication device, it is necessary to change the optical axis of the optical transmission path immediately with the detection of the optical signal interruption. However, it is very complicated to operate the entire device and change the optical axis. A large-scale mechanism is required.

  The present invention solves the above-described problems, and can change the optical axis of an optical signal transmitted from an optical space communication device dynamically and in a short time, thereby enabling communication to be performed by easily and quickly switching the communication partner. An object of the present invention is to provide an optical axis control device capable of resuming the operation.

In order to achieve such an object, the present invention is configured as follows.
(1) An optical axis control device that is used in an optical space communication device that receives and communicates with an optical signal emitted from an optical transmitter, and changes the optical axis of the optical signal in a specified direction. A reflecting plate is rotatably arranged on the optical axis of the signal, and the reflecting portion that directs the reflected optical axis of the optical signal in an arbitrary direction by changing the angle of the reflecting plate, and corresponds to the designated direction of the reflected optical axis A storage unit for storing the angle of the reflector, a monitoring unit for monitoring a communication state of the optical signal, and detecting a change in the optical signal optical axis when detecting blocking of the optical signal, and the monitoring unit When a change command is issued from the calculation unit that calculates the rotation angle from the difference between the current angle of the reflector and the angle stored in the storage unit, and based on the rotation angle obtained by the calculation unit And a drive unit that rotates the reflector.

(2) In the configuration of (1), the reflecting portion is characterized in that a rotation axis of the reflecting plate is made coincident with a direction of gravity.
(3) In the configuration of (1), the reflecting section includes first and second reflecting plates having different directions of rotation axes.
(4) In the configuration of (3), the first and second reflectors are characterized in that the directions of their rotation axes are orthogonal to each other.

(5) In the configuration of (3), each of the first and second reflecting plates satisfies the control angle range of the optical axis and has a minimum rotational moment.
(6) In the configuration of (3), the first and second reflectors are in a positional relationship in which the reflected optical signals are not shielded from each other and the rotational moment is minimum.

(7) In the configuration of (3), the driving unit includes an angle measuring unit that constantly measures the angles of the first and second reflecting plates.
(8) In the configuration of (7), the driving unit constantly adjusts the angles of the first and second reflectors based on angle information obtained by the angle measuring means to maximize the coupling efficiency. An angle adjusting means is provided.

(9) In the configuration of (3), when there are a plurality of designated directions of the reflected optical axis, the storage unit stores the angles of the first and second reflectors corresponding to the designated directions. It is characterized by.
(10) In the configuration of (1), the monitoring unit includes a communication state determination unit that constantly monitors a communication state and determines whether or not communication is interrupted.

  (11) In the configuration of (10), when there are a plurality of designated directions of the reflected optical axis and an angle corresponding to each designated direction is stored in the storage unit, the monitoring unit is the communication state determination unit. The present invention is characterized in that it has a function of always measuring a communication state and selecting an optimum set of rotation angles from a set of rotation angles stored in a storage unit.

(12) In the configuration of (1), the calculation unit obtains a drive voltage value generated by the drive unit from angle information received from the storage unit by a change command of the monitoring unit.
(13) In the configuration of (1), the calculation unit changes the driving voltage value notified to the driving unit according to the allowable driving voltage and the allowable response speed of the driving unit, and changes the driving plate to the specified angle. It is characterized by providing a means for matching the fastest.

(14) An optical space communication device according to the present invention is characterized in that the optical axis control device according to any one of (1) to (13) is integrally formed in an optical transmission / reception unit.
Here, the “space optical transmission device” described in Patent Document 1 performs fine adjustment of the optical axis using two types of lenses, and the object and configuration of the present invention for dynamic optical axis switching. Is different.

In addition, the “automatic tracking optical communication device” described in Patent Document 2 is different from the present invention in its purpose and configuration because it only tracks the receiver and cannot switch the optical axis in the designated direction.
Further, the “bidirectional spatial optical communication device” described in Patent Document 3 is a device for performing dynamic optical axis switching by finely adjusting the optical axis on the light receiving side by rotating one mirror in two axes. Is different in purpose and structure.

Further, the “space optical transmission device” described in Patent Document 4 only performs fine adjustment of the optical axis for matching the two-way optical axis, and is the purpose of the present invention for performing dynamic optical axis switching. The configuration is different.
In addition, the “optical wireless transmission / reception device, optical wireless device, and optical axis adjustment method of the optical wireless device” described in Patent Document 5 described above is an optical axis adjustment by rotating an integrated light emitter / receiver with two motors. Therefore, the method of switching the optical axis by rotating the reflecting plate is not presented, and the configuration is different from the present invention.

The “space optical communication device” described in Patent Document 6 only needs to finely adjust the optical axis by rotating a single mirror biaxially, and has a different object and configuration from the present invention.
The “space optical communication device” described in Patent Document 7 only performs fine adjustment of the optical axis using a variable apex angle prism, and is different from the present invention in its purpose and configuration.

In addition, the “latest information on outdoor space optical transmission technology” described in Non-Patent Document 2 describes the outline of the function for finely adjusting the optical axis of a part of the conventional optical space communication device and the reason why the function is necessary. It only mentions and does not mention dynamic optical axis switching.
Further, the CANOBEAM catalog described in Non-Patent Document 3 merely discloses the use image and specifications of a commercially available optical space communication device, the functions installed, and the like, and the optical axis switching of the present invention. Is not mentioned.

  According to the present invention, the optical axis of an optical signal transmitted from an optical space communication device can be changed dynamically and in a short time, and communication can be easily switched in a short time to resume communication. It is possible to provide an optical axis control device and an optical space communication device that can be used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a block diagram showing a configuration of an optical space communication system to which the present invention is applied. In FIG. 2, the same parts as those in the system shown in FIG.
In FIG. 2, the first space optical communication apparatus A includes an optical transmitter A1 and an optical receiver A2, and the second space optical communication apparatus B includes an optical transmitter B1 and an optical receiver B2, and is between the transmitter and the receiver. To enable transmission / reception of the optical signals P1 and P2. In this state, the first optical space communication device A is connected to the first network N1, and the second optical space communication device B is connected to the second network N2. One-to-one communication between the first and second networks is enabled by optical space communication between the communication devices A and B.

  Here, when the shielding object X enters the optical axis of the optical transmission line connecting the first and second optical space communication devices A and B, the mutual optical signals P1 and P2 do not reach and communication is impossible. Therefore, a third space optical communication device C is prepared and installed in a direction different from that of the second device B so that the shield X does not enter the optical axis. The third optical space communication apparatus C includes an optical transmitter C1 and an optical receiver C2, and is connected to the second network N2, and replaces the second optical space communication apparatus B with the first optical space communication apparatus. A enables optical communication with A.

  In the first optical space communication device A, an optical axis control device D1 is mounted on the optical axis of the optical signal emitted from the optical transmitter A1, and the optical signal received by the optical receiver A2 is on the optical axis. The second optical axis control device D2 is mounted on. These optical axis control devices D1 and D2 are respectively in the directions of the optical axes P1 and P2 that the first optical space communication device A faces the second optical space communication device B and the third optical space communication device C. This is a device for selectively changing the optical axes P3 and P4 to be directed. The second optical axis control device D2 has the same configuration as the first optical axis control device D1, and receives the same control instruction and executes the control.

  FIG. 3 is a block diagram showing the configuration of the first optical axis control device D1. In FIG. 3, the reflection unit D11 includes a reflection plate (not shown) rotatably disposed on the optical axis of the optical signal emitted from the optical transmitter A1 of the first optical space communication device A, and the driving unit D12. The angle of the reflecting plate can be arbitrarily changed by the rotational driving of the optical signal, and the reflected optical axis of the optical signal can be directed in an arbitrary direction. The drive unit D12 constantly measures the angle of the reflector, and the measurement angle is notified to the calculation unit D13.

  For such a reflection part D11, the storage part D14 previously stores reflector angle information for aligning the optical axis with the directions of the second optical space communication device B and the third optical space communication device C, respectively. Keep it. The monitoring unit D15 monitors the availability of optical communication from the reception state of the optical receiver A2 in the first optical space communication device A. For example, when the optical communication with the second optical space communication device B is interrupted due to the interruption of the optical signal, the arithmetic unit D13 is configured to switch the optical axis in the direction of the third optical space communication device C. A change order is issued.

  When the calculation unit D13 receives the change command from the monitoring unit D15, the calculation unit D13 reads the angle information corresponding to the change destination C from the storage unit D14, and calculates the rotation angle by calculating the difference from the current angle notified from the drive unit D12. Then, a drive voltage value corresponding to the rotation angle is obtained and set in the drive unit D12. The drive unit D12 rotationally drives a motor mounted on the rotating shaft of the reflecting plate with a given drive voltage. Thereby, the optical axis of the optical signal transmitted from the first optical space communication device A is switched from the second optical space communication device B to the third optical space communication device C.

  The case where the disconnection between the first and second optical space communication devices is detected and switched to the optical communication between the first and third space communication devices has been described above. Even when detecting the disconnection between the devices and switching to the optical communication between the first and second optical space communication devices, the angle information for the second space optical communication device B stored in advance in the storage unit D14 is used. Thus, the same processing can be performed.

The structure of the reflection part D11 will be further described in detail.
First, the reflecting portion D11 includes first and second reflecting plates D111 and D112. These reflectors D111 and D112 are arranged so that their rotation axes are orthogonal to each other.
4A is a diagram of the reflecting portion D1 as viewed from the rotation axis direction of the first reflecting plate D111, and FIG. 4B is a diagram of the reflecting portion D1 as viewed from the rotation axis direction of the second reflecting plate D112. is there.

4, the first reflector D111 is arranged to be incident on the optical signal P _A exactly its axis of rotation which is emitted from the optical transmitter A1. Then, it has an attitude of pan angle θ _P = α and tilt angle θ _T = 0 with respect to the light signal irradiation direction (incident optical axis), and reflects in the direction of pan angle θ _P = 2α and tilt angle θ _T = 0. Form the optical axis.

Since the rotation axis of the first reflection plate D111 and the rotation axis of the second reflection plate D112 are orthogonal to each other, the optical signal P _B reflected by the first reflection plate D111 is the reflection surface of the second reflection plate D112. Is incident on. The second reflecting plate D112 is arranged so that the optical signal P _B reflected by the first reflecting plate D111 is incident on the rotation axis. And it has an attitude of pan angle θ _P = 0 and tilt angle θ _T = −β with respect to the irradiation direction of the optical signal (incident optical axis). That is, when the optical axis incident angle of the optical signal P _B to the second reflecting plate D112 is 2β, the reflected optical axis P _C is formed in the direction of the pan angle θ _P = 0 and the tilt angle θ _T = −2β. The

Therefore, the optical axis P _A of the optical signal emitted from the optical transmitter A1 is changed to the optical axis P _C of the pan angle θ _P = 2α and the tilt angle θ _T = −2β by the reflecting portion D1.
By the way, the second reflector D112 receives and reflects the optical signal reflected from the first reflector D111. In this case, a sufficient length corresponding to the rotation angle range is required in the rotation axis direction of the first reflecting plate D111. For this reason, the reflection surface of the second reflecting plate D112 is distorted by its own weight, and there is a possibility that a rotational angle shift due to gravity occurs. Therefore, at least the second reflecting plate D112 has its rotational axis aligned with the direction of gravity. Thereby, the shift | offset | difference of the rotation angle which arises by gravity can be minimized.

As described above, when the optical signal PA is reflected by the first reflector D111 and a second reflector D112, is blocked by the first reflector D111 or second reflector D112 with irradiation of optical signal P _C There may be blind spots in the area. Therefore, in order to prevent the reflected optical signal from being shielded by the two reflecting plates D111 and D112, the positional relationship between the reflecting plates and the reflecting plate so as to satisfy the control angle range of the optical axis and minimize the rotational moment, respectively. The shape is designed by simulation.

  The rotation of the first and second reflectors D111 and D112 is driven and controlled by the drive unit D12. In the angle control, there is a possibility that a minute shift of the rotation angle due to a temperature change or a voltage drop may occur. Therefore, a function of always maximizing the coupling efficiency of the optical signal by constantly measuring the angle of each reflector and constantly adjusting each angle is added to the drive unit D12.

Taking the case of the system configuration shown in FIG. 2 as an example, the operation procedure of the optical axis control device having the above configuration will be described.
First, the storage unit D14 can store a plurality of sets of angles of the first and second reflectors D111 and D112 so that a plurality of places can be irradiated with optical signals. That is, in order to change the direction of irradiating the optical signal to the optical space communication device C, it is necessary to instruct the drive unit D12 about the angles of the first reflection plate D111 and the second reflection plate D112 to the optical space communication device C. There is. When the optical signal is interrupted between the first optical space communication device A and the third optical space communication device C, the direction in which the optical signal is irradiated is directed to the second optical space communication device B. Need to change. Therefore, as the direction in which the optical signal is desired to be emitted, a set of angles when the reflecting plates D111 and D112 are rotated in the direction toward the third optical space communication device C and the second light space communication device B are irradiated. For this purpose, a set of angles of the two reflecting plates D111 and D112 is stored in the storage unit D14.

  After the completion of the initial setting, the monitoring unit D15 grasps the counterpart device in the communication state and monitors whether or not the constant communication is maintained. And when the interruption | blocking of optical communication is detected, an optical axis change command is issued, another communication partner is searched, the angle information with respect to a corresponding communication apparatus is read from the memory | storage part D14, and it notifies to the calculating part D13. The calculation unit D13 calculates the difference between the current angle of each reflecting plate notified from the drive unit D12 and the angle read from the storage unit D14, that is, the rotation angle, and obtains the drive voltage value corresponding to the rotation angle. It sends to the drive part D12. In the drive part D12, the designated drive voltage is generated and supplied to a motor (not shown) mounted on the rotation shaft of each of the reflectors D111 and D112 to be driven to rotate.

  Here, if the drive voltage value corresponding to the angle information acquired from the storage unit D14 is directly supplied to the drive unit D12 in the calculation unit D13, the allowable voltage and the allowable response speed may be saturated. Therefore, if a function for calculating a voltage curve that reaches the target voltage most quickly and falls below the allowable voltage and the allowable response speed is added to the calculation unit D13, the saturation of the allowable voltage and the allowable response speed is avoided. The optical axis can be aligned with the target direction over time.

  FIG. 5 is a diagram showing the optical axis switching result of the above-described embodiment. The optical signal is irradiated from the first optical space communication device A to the second optical space communication device B, and the shield X is the first optical space. The light reception of the second optical space communication device B when the direction of irradiating the optical signal is changed to the third optical space communication device C because it has entered between the communication device A and the second optical space communication device B. It represents changes on the time axis of the intensity PW1 and the received light intensity PW2 of the third optical space communication device C.

  As is clear from FIG. 5, the light intensity PW1 of the second optical space communication device B immediately drops due to the light signal P1 being blocked by the shield X. By changing the irradiation direction of the optical signal P1 to the direction of the third optical space communication device C by the optical axis control device D1 that detects the interruption of communication, the light reception intensity PW2 of the third optical space communication device C is generated. Communication is resumed.

From the above, if the optical axis control device having the above configuration is used, even if the shielding object X enters the communication partner and the communication is interrupted, this is automatically detected and dynamically and in a short time. The optical axis can be changed, and optical communication with other communication partners can be resumed immediately.
The present invention is not limited to the above embodiment. For example, in the system of FIG. 2, the optical axis control device is mounted only on the first optical space communication device A, but may be mounted on the other communication devices B and C side.

  Further, the number of switching communication devices is not limited to two, and a larger number of communication devices may be prepared. In this case, when the communication block is detected in the monitoring unit D15, if the closest communication device is selected as the optimum switching device, the rotational drive amount of the reflecting plate can be reduced, which is effective.

  In the above embodiment, the rotation axes of the first and second reflectors are orthogonal to each other. However, in consideration of the case where angle adjustment is required depending on the size of the shielding object, etc. There is no need for an orthogonal relationship. Moreover, the number of reflecting plates is not limited to two, and can be selected as necessary.

  In the above embodiment, the monitoring unit D15 determines the communication state from the reception state of the optical receiver A2. You may make it judge a communication state by monitoring with an element.

In the above embodiment, the optical axis control device is configured as a single unit. However, the present invention can also be implemented in the same manner even if it is formed integrally with the transmission / reception unit of the optical space communication device.
Of course, various modifications may be made without departing from the scope of the present invention.

It is a block diagram which shows the structure of the conventional optical space communication system. It is a block diagram which shows the structure of the optical space communication system using the optical-axis control apparatus which concerns on this invention. It is a block diagram which shows one Embodiment of the optical axis control apparatus which concerns on this invention. It is a block diagram which shows the specific structure of the optical axis control apparatus which concerns on this invention. It is a measurement figure for demonstrating the mode at the time of switching of an optical space communication apparatus by operation | use of the optical axis control apparatus which concerns on this invention.

Explanation of symbols

  A: First optical space communication device, B: Second optical space communication device, C: Third optical space communication device, D1, D2: Optical axis control device, D11: Reflector, D111: First reflection Plate, D112 ... 2nd reflecting plate, D12 ... Drive part, D13 ... Calculation part, D14 ... Memory | storage part, D15 ... Monitoring part, N1, N2 ... Network, X ... Shielding object.

Claims (14)

An optical axis control device that is used in an optical space communication apparatus that receives and communicates with an optical signal emitted from an optical transmitter, and changes the optical axis of the optical signal in a specified direction,
A reflector that rotatably arranges a reflector on the optical axis of the optical signal and directs the reflected optical axis of the optical signal in an arbitrary direction by changing the angle of the reflector;
A storage unit for storing an angle of the reflecting plate corresponding to a designated direction of the reflected optical axis;
A monitoring unit that monitors the communication state of the optical signal and issues a command to change the optical signal optical axis when detecting the interruption of the optical signal;
When a change command is issued from the monitoring unit, a calculation unit that calculates a rotation angle from the difference between the current angle of the reflector and the angle stored in the storage unit;
An optical axis control device comprising: a drive unit that rotates the reflecting plate based on a rotation angle obtained by the calculation unit.   The optical axis control device according to claim 1, wherein the reflection unit causes a rotation axis of the reflection plate to coincide with a gravity direction.   The optical axis control device according to claim 1, wherein the reflection unit includes first and second reflection plates having different rotation axis directions.   4. The optical axis control device according to claim 3, wherein the first and second reflectors have directions of rotation axes orthogonal to each other.   4. The optical axis control device according to claim 3, wherein each of the first and second reflecting plates satisfies a control angle range of the optical axis and has a minimum rotational moment.   4. The optical axis control device according to claim 3, wherein the first and second reflectors are in a positional relationship in which the reflected optical signals do not shield each other and the rotational moment is minimum.   The optical axis control device according to claim 3, wherein the driving unit includes an angle measuring unit that constantly measures angles of the first and second reflecting plates.   The drive unit includes angle adjusting means that constantly adjusts the angles of the first and second reflecting plates based on angle information obtained by the angle measuring means to maximize coupling efficiency. The optical axis control device according to claim 7.   4. The light according to claim 3, wherein when there are a plurality of designated directions of the reflected optical axis, the storage unit stores angles of the first and second reflectors corresponding to the designated directions. Axis control device.   The optical axis control device according to claim 1, wherein the monitoring unit includes a communication state determination unit that constantly monitors a communication state and determines whether or not communication is interrupted. When there are a plurality of designated directions of the reflected optical axis, and an angle corresponding to each designated direction is stored in the storage unit,
The monitoring unit has a function of constantly measuring a communication state by the communication state determination unit and selecting an optimum set of rotation angles from a set of rotation angles stored in a storage unit. Item 11. The optical axis control device according to Item 10.   The optical axis control device according to claim 1, wherein the calculation unit obtains a drive voltage value generated by the drive unit from angle information received from the storage unit according to a change command of the monitoring unit.   The calculation unit includes means for changing the drive voltage value notified to the drive unit according to an allowable drive voltage and an allowable response speed of the drive unit and adjusting the reflector to the specified angle most quickly. The optical axis control device according to claim 12.   14. An optical space communication device, wherein the optical axis control device according to claim 1 is formed integrally with an optical transmission / reception unit.

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