JP2993450B2 - Optical tracking device for optical communication system between mobile units - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical tracking device for an optical communication system between mobile units, and more particularly to an optical tracking device suitable for an optical communication system between satellites.

[0002]

2. Description of the Related Art In space-propagation optical communication in which one or both devices are moving, such as inter-satellite optical communication, it is necessary to raster-scan one or both of the transmitted lights to establish a communication link. General.

Further, in order to satisfy the conflicting demands of realizing high-precision tracking while securing a wide range in which light of a partner device can be captured, a coarse capture tracking system having a wide capture tracking range but a slow response is required. Conversely, it is necessary to equip two types of acquisition and tracking systems, a narrow acquisition and tracking range but a quick response and accurate acquisition and tracking system.
The optical tracking device shown in FIG.

The optical tracking device shown in FIG. 5 includes an optical antenna 51 for receiving a partner light, an optical system 52 for adjusting an optical axis of an optical signal received by the optical antenna 51 according to an external operation amount, A coarse tracking sensor 53 that receives the output light from the optical system 52 in a relatively wide field of view, a fine tracking sensor 54 that receives the output light from the optical system 52 in a relatively narrow field of view, and an output light from the optical system 52 An operation amount is input to the optical system 52 so as to guide the axis to the approximate center of the coarse tracking sensor 53, and the optical system 52 is operated to guide the output optical axis from the optical system 52 to the approximate center of the fine tracking sensor 54. A tracking control circuit 55 for inputting an amount.

[0005] The optical antenna 51 has a mirror on the front surface, and the inclination of the incident optical axis can be adjusted by adjusting the direction of the mirror in accordance with an external drive signal. The optical system 52 includes a beam splitter 52a that divides the input light from the optical antenna 51 into two, and a coarse tracking mechanism 52b that changes the inclination of the front mirror of the optical antenna 51 to set the direction of the optical axis incident on the optical system 52. And a fine tracking mechanism 52c that includes a mirror whose direction can be freely changed according to an external signal and reflects the spectrum from the beam splitter 52a in a predetermined direction. Each of the coarse tracking sensor 53 and the fine tracking sensor 54 is an optical sensor capable of outputting a detection signal according to the incident position of light, and the field of view for detecting light is set wider in the coarse tracking sensor 53. The tracking control circuit 55 includes the coarse tracking sensor 5
A coarse tracking control unit 55a for controlling the direction of the optical antenna so that the optical axis incident on the sensor 3 is at the center of the sensor; and a fine tracking mechanism such that the optical axis incident on the fine tracking sensor 54 is at the center of the sensor. And a fine tracking control unit 55b for controlling the direction of the reflection mirror 52c. Reference numeral 56 denotes a coarse tracking mechanism angle detector that mechanically detects the direction of the optical antenna 51, and feeds back a detected value to the coarse tracking control unit 55a. On the other hand, reference numeral 57 denotes a fine tracking mechanism angle detector that detects the direction of the reflection mirror of the fine tracking mechanism 52c, and feeds back the detected value to the fine tracking control unit 55b. Generally, a potentiometer or the like, which is a mechanical detector, is employed as these detectors.

[0006] A part of the light beam received from the partner device by the optical antenna 51 is split by the beam splitter 52 a and input to the coarse tracking sensor 53. The coarse tracking sensor 53 outputs a shift vector from the sensor center position to the light incident position to the tracking control circuit 55. The magnitude of the shift vector represents an angle between the directional center of the optical antenna 51 (the center of the light receiving element of the coarse tracking sensor 53) and the incident direction of the light beam (hereinafter, referred to as a coarse tracking error angle). The coarse tracking control unit 55a provided in the tracking control circuit 55 drives and controls the coarse tracking mechanism 52c so that the coarse tracking error angle is set to zero. At this time, the output of the angle detector 56 is fed back to the control unit 55a and is reflected in the control of the coarse tracking mechanism 52b. The coarse tracking mechanism 52c adjusts the optical axis of the entire apparatus by driving a mirror placed in front of the optical antenna 51.

On the other hand, the other of the light split by the above-mentioned beam splitter 52 is input to a fine tracking sensor 54 via a fine tracking mechanism 52c. Here, as described above, the fine tracking mechanism 52c has a function of more precisely adjusting the optical axis of the incident light by adjusting the tilt of the mirror. The fine tracking sensor 54 calculates a deviation vector of the optical axis position received from the fine tracking mechanism 52c from the sensor center position,
5b. The magnitude of this displacement vector indicates the angle of inclination of the mirror provided in the fine tracking mechanism 52c from the reference position (hereinafter referred to as the fine tracking error angle). Fine tracking control unit 5
5b is a fine tracking mechanism 52 for setting the fine tracking error angle to zero.
c is driven and controlled. At this time, the output of the angle detector 57 is fed back to the control unit 55b, and the fine tracking mechanism 52
This is reflected in the control of c. Conventional examples of this type include Japanese Unexamined Patent Publication No.
-160916.

[0008]

However, in the above conventional example, one or both of the own apparatus and the other apparatus scan, and if light enters the field of view of the supplementary tracking sensor, the light is not lost. There was a disadvantage that the raster scan was immediately stopped to shift to the tracking state, and further, a light beam had to be emitted to the other party to stop the raster scan of the other apparatus. The reason is,
If the scanning is not stopped immediately after the capturing, the link is disconnected again.

After receiving the other party's light with the coarse tracking sensor, it is necessary to drive the coarse tracking mechanism so that the received light enters the field of view of the fine tracking sensor. In general, since the mirror angle is controlled using a two-axis gimbal, it takes a long time for the fine tracking sensor to receive light in a place where the driving speed is slow, and it is difficult to respond to a request to shorten this. There was an inconvenience.

[0010]

An object of the present invention is to improve the disadvantages of the prior art described above, and in particular, to reduce the time (capturing time) required to complete the capturing operation and shift to the tracking state after receiving the partner light. It is an object of the present invention to provide an optical tracking device for an interbody optical communication system.

[0011]

An optical communication apparatus according to the present invention comprises:
After receiving the other light with the coarse tracking sensor, the coarse tracking mechanism is moved at the same time as the fine tracking mechanism is moved to move the field of view of the fine tracking sensor in the direction of the other light. This is for shortening the time required until light is received by the tracking sensor, and employs the following configuration.

According to the first aspect of the present invention, there is provided an optical antenna for receiving a partner light, an optical system for adjusting an optical axis of an optical signal received by the optical antenna in accordance with an external operation amount, and A wide-field optical sensor that receives output light in a relatively wide field of view, a narrow-field optical sensor that receives output light from an optical system in a relatively narrow field of view, and a wide-field optical sensor that outputs the optical axis from the optical system A control unit that inputs an operation amount to the optical system so as to guide the optical system to the center, and inputs an operation amount to the optical system so as to guide the output optical axis from the optical system to substantially the center of the narrow-field optical sensor. Further, the control unit controls the operation for guiding the output optical axis from the optical system to the approximate center of the narrow-field optical sensor based on the amount of operation for guiding the optical axis output from the optical system to the approximate center of the wide-field optical sensor. While the amount is predicted and the output optical axis from the optical system is guided to the approximate center of the wide-field optical sensor, the predicted operation amount is input to the optical system.

Further, the invention according to claim 2 employs a configuration in which the control unit calculates a predicted operation amount based on an output of the wide-field light sensor.

Further, according to the third aspect of the present invention, the control unit continues to control the optical axis incident on the narrow-field optical sensor based on the predicted operation amount until the partner light is received by the narrow-field optical sensor. It has a configuration.

[0015] With the above, the above-mentioned object is achieved.

In these inventions, when the partner light is received by the wide-field optical sensor, the control unit controls the optical system to control the optical system so as to guide the light receiving position to the center based on the deviation of the light receiving position from the center. input. At the same time, the control unit predicts the moving direction and the moving amount of the optical axis on the narrow-field optical sensor based on the amount of operation for guiding the optical axis to the center of the wide-field optical sensor. An operation amount of the optical system for allowing the optical axis to be received at the center of the narrow-field optical sensor is predicted in advance, and the predicted operation amount is input to the optical system.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. The same parts as those in the conventional example are denoted by the same reference numerals, and redundant description will be omitted.

The optical tracking device shown in FIG. 1 has an optical antenna 51 for receiving a partner light and an optical system 52 for adjusting the optical axis of an optical signal received by the optical antenna 51 in accordance with an external operation amount.
And a coarse tracking sensor 53 (wide-field optical sensor) for receiving the output light from the optical system 52 in a relatively wide field of view, and a fine tracking sensor 54 for receiving the output light from the optical system 52 in a relatively narrow field of view ( An operation amount is input to the optical system 52 so as to guide the output optical axis from the optical system 52 to substantially the center of the coarse tracking sensor 53, and the output optical axis from the optical system 52 is precisely tracked. Tracking control circuit 10 (control unit) for inputting an operation amount to the optical system 52 so as to guide the optical system 52 to the approximate center of 53
And

The tracking control circuit 10 includes the optical system 5
The amount of operation for guiding the output optical axis from the optical system 52 to the approximate center of the fine tracking sensor 54 is predicted based on the amount of operation for guiding the output optical axis from the optical tracking device 2 to the approximate center of the coarse tracking sensor 53. While the output optical axis from the system 52 is guided to the approximate center of the coarse tracking sensor 53, the incident direction prediction calculation unit 1 that inputs the predicted operation amount to the optical system 52 is provided.

In this embodiment, the output vector from the coarse tracking sensor 53 (coarse tracking error angle and its error direction)
Is also input to the incident direction prediction calculation unit 1. The incident direction prediction calculation unit 1 performs a coarse tracking sensor 53 based on the coarse tracking error angle and its error direction, and the driving speed and driving direction of the coarse tracking mechanism 55 received from the coarse tracking control unit 55a.
The movement of the received light within the field of view is predicted, and the mirror angle operation amount (recentering angle) of the fine tracking mechanism 52c for causing the fine tracking sensor 57 to receive the received light in the shortest time is calculated from the prediction result. .

Further, the fine tracking control section 2 drives and controls the fine tracking mechanism 52c so that the fine tracking error angle becomes 0 at the time of tracking. On the other hand, at the time of capturing, the fine tracking mechanism 5 based on the result of the re-centering angle calculation of the incident direction prediction calculation unit 1 is set so that the time until light is received by the fine tracking sensor 54 is minimized.
2c is drive-controlled. Other configurations are the same as the conventional example.

Next, the overall operation of this embodiment will be described with reference to FIGS. Here, FIG. 2 shows a flowchart up to reception of the partner light by the fine tracking sensor. FIG. 3 is an explanatory diagram for explaining the operation of the incident direction prediction calculation unit 1.

In the initial state, as shown in FIG. 3A, the wide field of view 11 of the coarse tracking sensor 53 and the fine tracking sensor 5
It is assumed that four narrow visual fields 12 are located on concentric circles.
That is, if light enters the center of the coarse tracking sensor 53,
This is the state of the optical antenna 51 and the optical system 52 in which the light also enters the center of the fine tracking sensor 54. In the following description, the movement of the optical axis position incident on each of the tracking sensors 53 and 54 is relatively regarded as the movement of the visual field of each of the tracking sensors 53 and 54. In FIG. 3, the sensor field of view is shown as a circle for convenience regardless of the actual shape of the light receiving element.

In this state, if the opponent light is received by the optical antenna 51 and is received by the coarse tracking sensor 53 at the incident position L indicated by hatching in FIG. 3A (step S1 in FIG. 2), the coarse tracking sensor From 53, the coarse tracking error angle θ ₁
And the error direction thereof as a vector
Is input to the coarse tracking control unit 55a. Coarse tracking control unit 55
“a” calculates the driving direction and the driving speed of the coarse tracking mechanism 56 from the output of the coarse tracking sensor 53, and inputs them to the coarse tracking mechanism 52 b and the incident direction prediction calculation unit 1.

Thus, the coarse tracking control unit 55a drives the coarse tracking mechanism 52b so as to receive the light beam at the center of the coarse tracking sensor 53. At the same time, the incident direction prediction calculation unit 1 Is performed (step S2).

That is, as shown in FIG. 3A, assuming that the optical axis is incident on the incident position L in the field of view 11 of the coarse tracking sensor 53, the field of view 11 of the coarse tracking sensor 53 is changed by the coarse tracking controller 55a. It is moved in the direction of the arrow so as to capture the incident position L at its center. Then, as shown in FIG. 3 (b), the field of view 12 of the fine tracking sensor 54, which is concentric with the field of view 11 of the coarse tracking sensor 53, is displaced. The operation angle (recentering angle θ _r ) of the mirror M in the tracking mechanism 52c is predicted and calculated (step S3).

Then, the incident direction prediction calculation unit 1 inputs the calculated re-centering angle θ _r to the fine tracking control unit 2, and the fine tracking mechanism 52 c is driven by a predetermined amount by the fine tracking control unit 2 to drive the fine tracking sensor 53. The field of view 12 is brought closer to the field of view 11 of the coarse tracking sensor 53 (step S4).

Thus, when the precise tracking sensor 53 receives the partner light, the conventional general tracking control is performed thereafter. On the other hand, when the partner light is not received, the operation from step S2 is repeatedly executed (step S2).
5).

According to this, the incident direction prediction calculation unit 1
Since the position of the incident optical axis to the fine tracking sensor 54 is predicted in accordance with the position of the incident optical axis to the coarse tracking sensor 53, and the fine tracking mechanism is drive-controlled in advance so as to be received substantially at the center of the fine tracking sensor 54, It is possible to reduce the time (capture time) required from the reception of the partner light to the completion of the capture operation and transition to the tracking state.

In particular, since the control based on the predicted operation amount is repeatedly executed until the precise tracking sensor receives the partner light, the supplementary time can be further reduced.

Next, another embodiment of the present invention will be described with reference to FIG.

In the above embodiment, the fine tracking mechanism 52c
When a piezo actuator or the like is used, the size and weight can be reduced, but as a structural limitation, a mechanical detector such as a potentiometer cannot be adopted as the fine tracking mechanism angle detector. There are inconveniences. Therefore,
In such a case, as shown in FIG. 4, an independent light source 3 for emitting light to the mirror of the fine tracking mechanism 52c is newly provided to receive light emitted from the light source and reflected by the mirror of the fine tracking mechanism 52c. It is preferable to provide an optical fine tracking mechanism angle detector 57 at the position, not a mechanical one. Then, the fine tracking control unit 4 detects the mirror angle in the fine tracking mechanism 52c based on the output of the fine tracking mechanism angle detector 57. Even in this case, the same operation and effect as those of the above-described embodiment can be obtained, and the size and weight of the entire apparatus can be reduced.

Here, the light source 3 uses an independent light source as described above, and it is also possible to use the light transmitted back to the partner device by feeding it back.

[0034]

Since the present invention is constructed and functions as described above, according to this, when the other party's light is received by the coarse tracking sensor, the incident direction to the fine tracking sensor is predicted, and the fine tracking is previously performed in that direction. By arranging the mechanism, the time required for the light to enter the fine tracking sensor is reduced, so that the time required from the reception of light by the coarse tracking sensor to the completion of the fine tracking can be reduced. Particularly, since the control based on the predicted operation amount is repeatedly executed until the opposing light is received by the fine tracking sensor, the supplementary time can be further shortened. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment shown in FIG.

3A and 3B are explanatory diagrams illustrating a process of an incident direction prediction calculation unit in the embodiment illustrated in FIG. 1; FIG. 3A illustrates a state in which partner light enters a predetermined position with respect to a field of view of a coarse tracking sensor; FIG. 3B shows a state in which the centers of the fields of view of the coarse tracking sensor and the fine tracking sensor are deviated from concentricity, respectively.

FIG. 4 is a block diagram showing another embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incident direction prediction calculation part 2, 4 Fine tracking control part 3 Light source 10 Tracking control circuit (control part) 11 Field of view of coarse tracking sensor 12 Field of view of fine tracking sensor 51 Optical antenna 52 Optical system 52a Beam splitter 52b Coarse tracking mechanism 52c Fine Tracking mechanism 53 Coarse tracking sensor (wide-field optical sensor) 54 Fine tracking sensor (narrow-field optical sensor) 56 Coarse tracking mechanism angle detector 57 Fine tracking mechanism angle detector

Claims (3)

(57) [Claims] An optical antenna for receiving a partner light, an optical system for adjusting an optical axis of an optical signal received by the optical antenna according to an external operation amount, and a relatively wide output light from the optical system. A wide-field optical sensor that receives light in a visual field, a narrow-field optical sensor that receives output light from the optical system in a relatively narrow visual field, and guides an output optical axis from the optical system to approximately the center of the wide-field optical sensor. And a control unit for inputting an operation amount to the optical system so as to input an operation amount to the optical system and guiding an output optical axis from the optical system to substantially the center of the narrow-field optical sensor. In the apparatus, the control unit may set the output optical axis from the optical system to substantially the center of the narrow-field optical sensor based on an operation amount for guiding the output optical axis from the optical system to the approximate center of the wide-field optical sensor. Predict the amount of operation to guide, and output light from the optical system The while leading to substantially the center of the wide field light sensor, optical tracking device which is characterized in that inputs the predicted manipulated variable to the optical system. 2. The optical tracking device according to claim 1, wherein the control unit calculates the predicted operation amount based on an output of the wide-field optical sensor. 3. The control unit according to claim 2, wherein the control of the incident optical axis to the narrow-field optical sensor based on the predicted operation amount is continued until the partner light is received by the narrow-field optical sensor. 3. The optical tracking device according to 1 or 2.