JP6080516B2 - Acquisition and tracking device - Google Patents

Description

  The present invention relates to a capture and tracking device that captures the propagation direction of incoming light and establishes tracking control of the optical path of received light in order to establish and maintain communication in optical communication in which laser light is propagated.

  Conventionally, a capture and tracking device that is independent from the communication receiver is provided, and a part of the optical path of the received light is branched and input to a photodiode (photoelectric element) of the capture and tracking device to perform capture and tracking control. However, this conventional technique has a problem in that it is necessary to increase the optical power required for establishment of a communication circuit by increasing the optical power for acquisition and tracking.

  In order to solve this problem, the optical beam tracking device disclosed in Patent Document 1 includes a tracking detector including four photodetectors, and detects and detects an optical signal incident on each photodetector. The arrival angle of the received light beam is detected based on the difference between the four signal voltages. Specifically, the signal voltage detected by each photodetector is input to an arithmetic circuit, a normalized error voltage is calculated, and an azimuth angle corresponding to the horizontal direction of the tracking detector is calculated based on the normalized error voltage. The elevation angle corresponding to the vertical direction of the tracking detector is estimated, and the optical polarizer is controlled so that the received light is located on the central axis.

Japanese Patent Laid-Open No. 2-216076

  However, in the technique disclosed in Patent Document 1 described above, the angle detection range and the response time are in a trade-off relationship, and in order to perform high-speed communication, it is necessary to reduce the light receiving area of the received light, which is stable. There is a problem that it is difficult to achieve both a wide angular error detection range for ensuring communication and high-speed communication.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a capture and tracking device that achieves both a wide angle error detection range for ensuring stable communication and high-speed communication. And

An acquisition and tracking device according to the present invention includes an optical antenna that receives a spatially propagated laser beam, a local light source that outputs local light having substantially the same wavelength as the received light of the optical antenna, and a received light and a local light that are transmitted as light waves. A hybrid element that combines and outputs a plurality of outgoing lights having an outgoing angle equal to the incident angle of the received light, a photoelectric converter that converts the outgoing lights output from the hybrid element into detection signals, and a photoelectric converter The coarse capture tracking mechanism that generates a coarse capture error signal that captures the detected signal at a wide angle with respect to the exit surface of the hybrid element , and the detection signal converted by the photoelectric conversion unit is captured with high accuracy in the exit direction of the hybrid element A capture tracking sensor having a fine capture tracking mechanism that generates a fine capture error signal, and a coarse capture control signal that drives the coarse capture tracking mechanism using the coarse capture error signal generated by the capture tracking sensor A coarse correction control signal generation circuit to be generated, a fine capture control signal generation circuit for generating a fine capture control signal that drives a fine capture tracking mechanism using a fine capture error signal generated by the capture and tracking sensor, and a photoelectric converter And a phase synchronization control circuit that generates a frequency error signal based on the detected signal and outputs a feedback signal to the local light source. The photoelectric conversion unit is divided into two in the horizontal direction with respect to the emission surface of the receiving element. And a second photoelectric conversion region, and a horizontal photoelectric converter having a third photoelectric conversion region in contact with the first and second photoelectric conversion regions, and a second photoelectric converter divided into two in a direction perpendicular to the emission surface of the receiving element A plurality of vertical photoelectric converters having a first photoelectric conversion region and a third photoelectric conversion region in contact with the first and second photoelectric conversion regions are arranged in a plurality of orthogonal directions. Photoelectric change The detection signal output from the third photoelectric conversion region of the detector and the third photoelectric conversion region of the vertical photoelectric converter is used as a coarse capture error, and a coarse capture error signal is generated from the coarse capture error. Fine capture from tracking error calculated by calculating the center of gravity of detection signals output from the first and second photoelectric conversion regions of the horizontal photoelectric converter and the first and second photoelectric conversion regions of the vertical photoelectric converter An error signal is generated .

  According to the present invention, it is possible to secure a wide angular error detection range and realize high-speed communication.

1 is a diagram illustrating a configuration of a capture and tracking device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a configuration of an optical hybrid element of the capture and tracking device according to the first embodiment. It is a figure which shows the division | segmentation pattern and connection of the division | segmentation type photoelectric converter of the acquisition tracking apparatus by Embodiment 1. FIG. FIG. 6 is a diagram illustrating an example of signal output from each split photoelectric converter when the arrival angle of incoming light is shifted in the X direction in the acquisition and tracking device according to the first embodiment. It is a figure which shows the structure of the acquisition tracking apparatus by Embodiment 2. FIG. It is a figure which shows the division | segmentation pattern and connection of the division | segmentation type photoelectric converter of the acquisition tracking apparatus by Embodiment 2. FIG. FIG. 10 is a diagram illustrating a configuration of a capture and tracking device according to a third embodiment. It is a figure which shows the division | segmentation pattern and connection of the division | segmentation type photoelectric converter of the acquisition tracking apparatus by Embodiment 3. FIG. FIG. 10 is a diagram illustrating a configuration example of a defocus controller of a capture and tracking device according to a fourth embodiment. It is a figure which shows the reception image at the time of the wide angle detection of the acquisition tracking apparatus by Embodiment 4 and a highly accurate angle detection. Numerical calculation results of detection accuracy and dynamic range of acquisition and tracking device according to embodiment 4 It is a figure which shows the structure of the acquisition tracking apparatus by Embodiment 4. FIG. It is a figure which shows the division | segmentation pattern of the division | segmentation type photoelectric converter of the acquisition tracking apparatus by Embodiment 4, and connection of each division | segmentation type photoelectric converter and each photoelectric converter. It is a figure which shows an example of the signal output from each division | segmentation type photoelectric converter when the arrival angle of incoming light changes. 10 is a flowchart illustrating an operation up to the completion of tracking of the acquisition and tracking device according to the fourth embodiment. It is a figure which shows the structure of the acquisition tracking apparatus by Embodiment 5. FIG. It is a figure which shows the division | segmentation pattern of the division | segmentation type photoelectric converter of the acquisition tracking apparatus by Embodiment 5, and the connection of each division | segmentation type photoelectric converter. It is a figure which shows the structure of the frequency discrimination circuit of the acquisition tracking apparatus by Embodiment 5. FIG. It is a figure which shows the image of the reception spectrum of the frequency discrimination circuit of the acquisition tracking apparatus by Embodiment 5. FIG. 10 is a flowchart showing an operation of the acquisition and tracking apparatus according to the fifth embodiment.

Embodiment 1 FIG.
FIG. 1 is a diagram showing the configuration of a capture and tracking apparatus according to Embodiment 1 of the present invention.
In FIG. 1, the acquisition and tracking device includes an optical antenna 1, a local light source 2, an optical hybrid element 3, first, second, third and fourth divided photoelectric converters (horizontal photoelectric converter and vertical photoelectric converter). 4, 5, 6, 7, first and second coarse acquisition error signal generation circuits (rough acquisition tracking mechanism) 8, 10, first and second fine acquisition error signal generation circuits (fine acquisition tracking mechanism) 9 , 11, 11, 11, 11 differential amplifier circuit 13, second differential amplifier circuit 14, Costas loop circuit 15, coarse capture control signal generation circuit 16, and fine capture control signal generation circuit 17. It is configured.

  The optical antenna 1 receives incoming light that propagates through space. The local light source 2 is a light source that outputs local light having substantially the same wavelength as the incoming light. The optical hybrid element 3 has a characteristic of combining local light with incoming light and maintaining a one-to-one relationship between the incident angle and the outgoing angle. The first, second, third, and fourth divided photoelectric converters 4, 5, 6, and 7 each have a small angle detection range, that is, a small area and a fast response time (for high-speed communication). And a photoelectric conversion region having a large angle detection range, that is, a large region. A photoelectric conversion region having a small region and a photoelectric conversion region having a large region are arranged orthogonally.

  The first and second coarse acquisition error signal generation circuits 8 and 10 obtain tracking error signals in a predetermined direction from detection signals obtained from the first to fourth divided photoelectric converters 4, 5, 6, and 7. . Similarly, the first and second fine capture error signal generation circuits 9 and 11 acquire tracking error signals in a predetermined direction from detection signals obtained from the respective divided photoelectric converters 4, 5, 6, and 7. The coarse acquisition control signal generation circuit 16 generates a feedback signal based on the output signals of the first and second coarse acquisition error signal generation circuits 8 and 10 and outputs the feedback signal to the optical antenna 1. Similarly, the fine capture control signal generation circuit 17 generates a feedback signal based on the output signals of the first and second fine capture error signal generation circuits 9 and 11 and outputs the feedback signal to the optical antenna 1. As a result, the generated feedback signal is fed back to the acquisition and tracking sensor 12.

  The first differential amplifier circuit 13 and the second differential amplifier circuit 14 each output an I signal (In-phase signal) and a Q signal (Quadrature-phase signal) that are 90 degrees out of phase. The Costas loop circuit 15 inputs the frequency error signal of the I signal and the Q signal output from the first differential amplifier circuit 13 and the second differential amplifier circuit 14 to the local light source 2. By feeding back the I signal and the Q signal to the local light source 2, phase synchronization between the incoming light and the local light is established. The first differential amplifier circuit 13, the second differential amplifier circuit 14, and the Costas loop circuit 15 constitute a phase synchronization control circuit.

Next, the details of the optical hybrid element 3 will be described with reference to FIG.
FIG. 2 is a diagram showing the configuration of the optical hybrid element of the acquisition and tracking device according to the first embodiment.
The optical hybrid element 3 includes a half-wave plate (hereinafter referred to as HWP) 203, a quarter-wave plate (hereinafter referred to as QWP) 204, one beam splitter (hereinafter referred to as BS) 205, and a polarization It consists of separation splitters (hereinafter referred to as PBS) 206, 207.
The half-wave plate 203 gives an optical path difference of λ / 2 (a phase difference of 180 degrees) between two orthogonal polarization components having a specific wavelength. The quarter-wave plate 204 gives an optical path difference (90-degree phase difference) of λ / 4 between two orthogonal polarization components of a specific wavelength. The BS 205 combines and branches the incident light and emits it. The PBSs 206 and 207 are separated into two orthogonal polarization components for incident light and output.

FIG. 2A shows a case where the incident angle of the incoming light 201 does not change, and FIG. 2B shows a case where the incident angle of the incoming light 201 changes by Δθ.
First, a description will be given with reference to FIG. The incoming light (received light) 201 received by the optical antenna 1 is converted into linearly polarized light that is not 0, 90, 180, or 270 degrees by the HWP 203, and the local light 202 generated by the local light source 2 is converted into circularly polarized light by the QWP 204. The These two signal lights are multiplexed and branched by the BS 205 so as to have the same optical path. The signal light transmitted through the BS 205 is separated for each polarization by the PBS 206 and the PBS 207, and four signals 208, 209, 210, and 211 each having a phase difference of 90 degrees are generated and output from four output ports (not shown). Is output. Note that there is no angular difference between the incoming light 201 and the station transmitted light 202.

  When the output signal of the output port is specifically defined, for example, the first output port (I channel output port) outputs a signal with a phase difference of 0 degree added (no phase added), and the second output port A signal with a phase difference of 180 degrees is output from the (I channel output port), and a signal with a phase difference of 90 degrees is output from the third output port (Q channel output port). A signal with a phase difference of 270 degrees is output from the output port (Q channel output port). In the following description, the relationship between the first to fourth output ports and the added phase difference is described as having the above-described relationship. However, if the correspondence between each output port and the phase difference is clear. These can be changed as appropriate.

On the other hand, when the incident angle of the incoming light 201 changes by Δθ as shown in FIG. 2B, the four signals 208 ′, 209 ′, 210 ′, and 211 ′ that are output are all with respect to the local light 202. The incoming light 201 is output with an angle Δθ.
2A and 2B, the output signals 208 and 208 'and the signals 209 and 209' are in-phase component I-channel signals, and the signals 210 and 210 'and the signals 211 and 211' are orthogonal. This is a component Q channel signal. When described in association with each of the output ports described above, the I channel signal is output from the first and second output ports, and the Q channel signal is output from the second and third output ports.

Next, the detailed configuration of the first to fourth divided photoelectric converters 4, 5, 6, and 7 of the tracking acquisition sensor and the connection to the first to fourth divided photoelectric converters 4, 5, 6, and 7 are connected. Each captured error signal generation circuit will be described.
FIG. 3 is a diagram showing a division pattern of the division type photoelectric converter of the acquisition and tracking device according to the first embodiment and the connection of each acquisition error signal generation circuit. FIG. 4 is a diagram illustrating an example of signal output from each split photoelectric converter when the arrival angle of the incoming light 201 is shifted in the X direction.

  As shown in FIG. 3, the first to fourth divided photoelectric converters 4, 5, 6, and 7 are each composed of three regions. The second divided photoelectric converter 5 will be described as an example. The second divided photoelectric converter 5 is divided into photoelectric conversion regions 5a and 5b having a small area and a photoelectric conversion region 5c having a large area. The photoelectric conversion regions 5a and 5b and the photoelectric conversion region 5c are arranged orthogonally. A photoelectric conversion region having a small area has a characteristic that the angle detection range is small and the response time is fast. On the other hand, the photoelectric conversion region having a large area has a characteristic that the angle detection range is wide. Similarly, the first divided photoelectric converter 4, the third divided photoelectric converter 6, and the fourth divided photoelectric converter 7 are also configured by three photoelectric conversion regions.

The three regions constituting each of the divided photoelectric converters 4, 5, 6, and 7 have different arrangement patterns for the corresponding output ports.
In the first split type photoelectric converter 4 to which the output signal of the first output port is input, the photoelectric conversion regions 4a and 4b of the small region are horizontal with respect to the beam exit surface A (hereinafter referred to as X direction). The large photoelectric conversion region 4c is arranged in a direction perpendicular to the beam exit surface A (hereinafter referred to as Y direction). Similarly, in the second split photoelectric converter 5 to which the output signal of the second output port is input, the photoelectric conversion regions 5a and 5b in the small region are in the X direction, and the photoelectric conversion region 5c in the large region is in the Y direction. Deploy. On the other hand, in the third split photoelectric converter 6 to which the output signal of the third output port is input, the photoelectric conversion regions 6a and 6b in the small region are arranged in the Y direction, and the photoelectric conversion region 6c in the large region is arranged in the X direction. In the fourth split photoelectric converter 7 to which the output signal of the fourth output port is input, the photoelectric conversion regions 7a and 7b in the small region are arranged in the Y direction, and the photoelectric conversion region 7c in the large region is arranged in the X direction. To do. In FIG. 3, reference numerals 4d, 5d, 6d, and 7d denote light receiving spots.

  By arranging the divided photoelectric converters 4, 5, 6, and 7 orthogonally as shown in FIG. 3, the X component fine acquisition error signal and the Y component coarse acquisition error from the first divided photoelectric converter 4 are arranged. A signal is acquired, an X component fine acquisition error signal and a Y component coarse acquisition error signal are acquired from the second divided photoelectric converter 5, and a Y component fine acquisition is acquired from the third divided photoelectric converter 6. An error signal and an X component coarse acquisition error signal are acquired, and a Y component fine acquisition error signal and an X component coarse acquisition error signal are acquired from the fourth split photoelectric converter 7.

The fine capture error signal in the X direction of the first split photoelectric converter 4 is output to the first differential amplifier circuit 13, and the coarse capture error signal in the Y direction passes through the first coarse capture error signal generation circuit 8. Then, it is output to the coarse acquisition control signal generation circuit 16.
The fine capture error signal in the X direction of the second split type photoelectric converter 5 is output to the first differential amplifier circuit 13 and is finely controlled via the first fine capture error signal generation circuit 9. The signal is output to the signal generation circuit 17.
The fine capture error signal in the Y direction of the third divided photoelectric converter 6 is output to the second differential amplifier circuit 14, and the coarse capture error signal in the Y direction passes through the second coarse capture error signal generation circuit 10. Then, it is output to the coarse acquisition control signal generation circuit 16.
The fine capture error signal in the Y direction of the fourth split photoelectric converter 7 is output to the second differential amplifier circuit 14 and is also finely controlled via the second fine capture error signal generation circuit 11. The signal is output to the signal generation circuit 17.

Next, detailed processing of the acquisition tracking sensor 12 will be described.
First, acquisition of an error signal will be described.
The detection signal obtained from the photoelectric conversion region 5a of the second split photoelectric converter 5 is defined as a signal Sa1, and the detection signal obtained from the photoelectric conversion region 5b is defined as a signal Sa2, based on the following equation (1) in the X direction. Get tracking error.
X-direction tracking error = (Sa1-Sa2) / (Sa1 + Sa2) (1)
Similarly, a detection signal obtained from the photoelectric conversion region 7a of the fourth split photoelectric converter 7 is a signal Sb1, and a detection signal obtained from the photoelectric conversion region 7b is a signal Sb2, based on the following equation (2). To obtain the Y direction tracking error.
Y direction tracking error = (Sb1−Sb2) / (Sb1 + Sb2) (2)

The detection signal obtained from the photoelectric conversion region 6c of the third divided photoelectric converter 6 is the signal Sa3, and the detection signal obtained from the photoelectric conversion region 4c of the first divided photoelectric converter 4 is the signal Sb3. As shown in the following formulas (3) and (4), it is used for a coarse capture error having a large angle detection range.
X direction coarse capture error = Sa3 (3)
Y direction coarse capture error = Sb3 (4)

Next, acquisition of a communication signal will be described.
The detection signal obtained from the first split photoelectric converter 4 with respect to the signal output from the first output port is a communication signal generated based on the following equation (5).
First output port communication signal (signal phase 0 [deg.])
= Sa1 (4a) + Sa2 (4b) (5)
Similarly, with respect to signals output from the second to fourth output ports, detection signals obtained from the second to fourth divided photoelectric converters 5, 6, and 7 are expressed by the following equation (6), It becomes a communication signal shown in (7) and (8).
Second output port communication signal (signal phase 180 [deg.])
= Sa1 (5a) + Sa2 (5b) (6)
Third output port communication signal (signal phase 90 [deg.])
= Sa1 (6a) + Sa2 (6b) (7)
Fourth output port communication signal (signal phase 270 [deg.])
= Sa1 (7a) + Sa2 (7b) (8)

  The first output port communication signal and the second output port communication signal are output to the second differential amplifier circuit 14, and the third output port communication signal and the fourth output port communication signal are first differential amplified. Output to the circuit 13. Thereby, the light source noise of the local light source 2 is removed. The first differential amplifier circuit 13 and the second differential amplifier circuit 14 respectively output an I channel signal and a Q channel signal that are 90 degrees out of phase. By inputting these into the Costas loop circuit 15 and feeding back the frequency error signal to the local light source 2, phase synchronization between the incoming light 201 and the local light 202 is established.

  On the other hand, the output signals of the first and second coarse acquisition error signal generation circuits 8 and 10 are fed back to the optical antenna 1, that is, the acquisition tracking sensor 12 via the coarse acquisition control signal generation circuit 16. The output signals of the first and second fine capture error signal generation circuits 9 and 11 are fed back to the optical antenna 1, that is, the capture and tracking sensor 12 via the fine capture control signal generation circuit 17.

  As described above, according to the first embodiment, the optical hybrid element 3 that generates an output signal that is 90 degrees out of phase with each other by optically synthesizing local light having substantially the same wavelength as the incoming light, and spatially The first to fourth divided photoelectric converters 4, 5, 6, and 7 divided into three are used to perform operations using output signals from the divided photoelectric converters 4, 5, 6, and 7, Since the tracking error signal and the communication signal are generated from the calculation result, the angle detection function and the reception function for high-speed optical communication can be compatible, and the acquisition tracking sensor function and the communication reception function can be compatible. . Thereby, it is not necessary to branch the incoming light for angle detection, and the required transmission light power can be reduced. Furthermore, it is not necessary to provide a capture and tracking sensor separately from the communication receiver, and the apparatus can be downsized.

  Further, according to the first embodiment, the first to fourth divided photoelectric converters Nos. 4, 5, 6, and 7 are divided into two photoelectric conversion regions with a fast response time and one with a large angle detection range. Since the photoelectric conversion region is used, it is possible to have both an angle detection function with a wide angle range and a highly accurate angle detection function, and the apparatus can be downsized.

  Further, according to the first embodiment, the output signal of the first output port of the four-output optical hybrid element 3 is detected by the first split photoelectric converter 4, and the output signal of the second output port is detected. Detected by the second split type photoelectric converter 5, the output signal of the third output port is detected by the third split type photoelectric converter 6, and the output signal of the fourth output port is detected by the fourth split type photoelectric converter. Since it is configured to detect by the converter 7, the first to fourth output ports can be arranged adjacent to each other, the optical path length difference between ports and the electrical length difference in the optical hybrid element can be set short, and high speed Sensitivity can be increased even for communication signals.

  In the first embodiment described above, a description has been given assuming that optical 90-degree hybrid is used for the optical hybrid element 3 and optical homodyne communication is performed, but the present invention is limited to the communication method and optical 90-degree hybrid described above. For example, the present invention can also be applied to the case where two output ports of an optical 180-degree hybrid having an incident angle and an emission angle in a one-to-one relationship are used as the optical hybrid element 3.

Embodiment 2. FIG.
In the first embodiment described above, the configuration in which the fine capture error signal is detected using the I channel signal and the Q channel signal is shown. However, in the second embodiment, the fine capture error signal is obtained using two Q channel signals. The structure to detect is shown. In the following, a case where an optical 90-degree hybrid is used as the optical hybrid element 3 as in the first embodiment will be described as an example.
FIG. 5 is a diagram illustrating a configuration of the acquisition and tracking apparatus according to the second embodiment. Each component of the acquisition and tracking device is the same as that of the first embodiment, but the connection of each component is changed.
The first split photoelectric converter 4 is connected to the second fine capture error signal generation circuit 11 and the second differential amplifier circuit 14. The second split photoelectric converter 5 is connected to the first fine capture error signal generation circuit and the second differential amplifier circuit 14. The third split photoelectric converter 6 is connected to the second coarse capture error signal generation circuit 10 and the first differential amplifier circuit 13. The fourth split photoelectric converter 7 is connected to the first coarse acquisition error signal generation circuit 8 and the first differential amplifier circuit 13.

FIG. 6 is a diagram illustrating a division pattern of the division photoelectric converter of the acquisition and tracking device according to the second embodiment and connection of signal calculation processing.
The first split photoelectric converter 4 detects a capture error signal using the Q channel signal output from the third output port, and the second split photoelectric converter 5 outputs from the fourth output port. The captured error signal is detected using the Q channel signal. On the other hand, the third split-type photoelectric converter 6 detects the capture error signal using the I channel signal output from the first output port, and the fourth split-type photoelectric converter 7 has the second output port. The capture error signal is detected using the I channel signal output from the.

  In the first split photoelectric converter 4, the photoelectric conversion regions 4a and 4b are arranged in the Y direction and the photoelectric conversion region 4c is arranged in the X direction. In the second split photoelectric converter 5, the photoelectric conversion regions 5a and 5b are arranged in the X direction and the photoelectric conversion region 5c is arranged in the Y direction. In the third split photoelectric converter 6, the photoelectric conversion regions 6a and 6b are arranged in the Y direction and the photoelectric conversion region 6c is arranged in the X direction. In the fourth split photoelectric converter 7, the photoelectric conversion regions 7a and 7b are arranged in the X direction and the photoelectric conversion region 7c is arranged in the Y direction.

  In the first split photoelectric converter 4 and the second split photoelectric converter 5 using the output signal of the Q channel port, the conversion regions 4a and 4b and the conversion regions 5a and 5b are orthogonal to each other in the X and Y directions. Placed in. Further, in the third divided photoelectric converter 6 and the fourth divided photoelectric converter 7 that use the output signal of the I channel port, the conversion region 6c and the conversion region 7c are arranged so as to be orthogonal to each other in the X and Y directions. The

  As shown in FIG. 6, by arranging the first to fourth divided photoelectric converters 4, 5, 6 and 7 orthogonally, the Y component fine capture error signal and X Obtain the coarse acquisition error signal of the component. Further, an X component fine acquisition error signal and a Y component coarse acquisition error signal are obtained from the second divided photoelectric converter 5, and a Y component fine acquisition error signal and an X component are acquired from the third divided photoelectric converter 6. A component coarse acquisition error signal is acquired, and an X component fine acquisition error signal and a Y component coarse acquisition error signal are acquired from the fourth split photoelectric converter 7.

In the first and second divided photoelectric converters 4 and 5, the fine capture error signal generated using the Q channel signal is input to the first and second fine capture error signal generation circuits 9 and 11. On the other hand, in the third and fourth split type photoelectric converters 6 and 7, the coarse acquisition error signal generated using the I channel signal is input to the first and second coarse acquisition error signal generation circuits 8 and 10. The
The configuration for acquiring the error signal and the communication signal based on the fine acquisition error signal and the coarse acquisition error signal acquired from the first to fourth divided photoelectric converters 4, 5, 6, and 7 is the same as that of the first embodiment. Since it is the same, description is abbreviate | omitted.

  As described above, according to the second embodiment, the first and second split-type photoelectric converters 4 and 5 use the output signal of the Q channel port and the X component fine acquisition error signal and the Y component. Since the Q channel port output signal is used for fine capture tracking error detection, deterioration of the output signal of the I channel port used for communication can be suppressed. . Thereby, high sensitivity of communication can be realized. In addition, it is possible to achieve both a tracking error detection function in a wide angle range and a reception function for high-speed communication.

  In the first embodiment described above, a description has been given assuming that optical 90-degree hybrid is used for the optical hybrid element 3 and optical homodyne communication is performed, but the present invention is limited to the communication method and optical 90-degree hybrid described above. For example, the present invention can also be applied to the case where two output ports of an optical 180-degree hybrid having an incident angle and an emission angle in a one-to-one relationship are used as the optical hybrid element 3.

Embodiment 3 FIG.
In the third embodiment, in the 90-degree hybrid light of the hybrid element, the orthogonal polarization angle of the incoming light 201 is set to 45 ° or more, so that the signal ratio of the I channel to the Q channel is set to I channel> Q channel and fine capture is performed. 1 shows a configuration in which an output signal of an I channel port is used for error signal detection. In the following, a case where an optical 90-degree hybrid is used as the optical hybrid element 3 as in the first embodiment will be described as an example.
FIG. 7 is a diagram illustrating the configuration of the acquisition and tracking apparatus according to the third embodiment. Each component of the acquisition and tracking device is the same as that of the first embodiment, but the connection of each component is changed.
The first split photoelectric converter 4 is connected to the second coarse capture error signal generation circuit 10 and the second differential amplifier circuit 14. The second split photoelectric converter 5 is connected to the first coarse acquisition error signal generation circuit 8 and the second differential amplification circuit 14. The third split photoelectric converter 6 is connected to the second fine capture error signal generation circuit 11 and the first differential amplifier circuit 13. The fourth split-type photoelectric converter 7 is connected to the first fine capture error signal generation circuit 9 and the first differential amplifier circuit 13.

  Further, the angle of the HWP 203 of the hybrid element is set so that the output signal ratio is I channel> Q channel. More specifically, the outputs of the first and second output ports that output the I channel signal are “10”, and the outputs of the third and fourth output ports that output the Q channel signal are “1”. Arrange the elements. The output ratio described above is an example and can be changed as appropriate.

FIG. 8 is a diagram showing a division pattern of the division photoelectric converter of the acquisition and tracking device according to the third embodiment and connection of signal calculation processing.
The arrangement of the conversion regions of the first to fourth divided photoelectric converters 4, 5, 6 and 7 is the same as that of the second embodiment, and the first divided photoelectric converter 4 has a third output port. The capture error signal is detected using the Q channel signal output from the second output, and the second split photoelectric converter 5 detects the capture error signal using the Q channel signal output from the fourth output port. The first divided photoelectric converter 4 and the second divided photoelectric converter 5 using the Q channel signal are arranged such that the conversion region 4c and the conversion region 5c are orthogonal to the X and Y directions, respectively.

  On the other hand, the third split-type photoelectric converter 6 detects the capture error signal using the I channel signal output from the first output port, and the fourth split-type photoelectric converter 7 has the fourth output port. The capture error signal is detected using the I channel signal output from the. In the third divided photoelectric converter 6 and the fourth divided photoelectric converter 7 using the I channel signal, the conversion regions 6a and 6b and the conversion regions 7a and 7b are arranged orthogonal to the X and Y directions, respectively.

  As shown in FIG. 8, by arranging the first to fourth divided photoelectric converters 4, 5, 6 and 7 orthogonally, the Y component fine capture error signal and X Obtain the coarse acquisition error signal of the component. Further, an X component fine acquisition error signal and a Y component coarse acquisition error signal are obtained from the second divided photoelectric converter 5, and a Y component fine acquisition error signal and an X component are acquired from the third divided photoelectric converter 6. A component coarse acquisition error signal is acquired, and an X component fine acquisition error signal and a Y component coarse acquisition error signal are acquired from the fourth split photoelectric converter 7.

In the third and fourth split photoelectric converters 6 and 7, the fine capture error signal generated using the I channel signal is input to the first and second fine capture error signal generation circuits 9 and 11. On the other hand, in the first and second split photoelectric converters 4 and 5, the coarse acquisition error signal generated using the Q channel signal is input to the first and second coarse acquisition error signal generation circuits 8 and 10. The
The configuration for acquiring the error signal and the communication signal based on the fine acquisition error signal and the coarse acquisition error signal acquired from the first to fourth divided photoelectric converters 4, 5, 6, and 7 is the same as that of the first embodiment. Since it is the same, description is abbreviate | omitted.

  As described above, according to the third embodiment, since the branching ratio of the optical hybrid element 3 is adjusted and the I channel port output is set to a rich signal level, the signal level of the incoming light is attenuated. Even in this case, the tracking error detection in the wide-angle range and the reception function for high-speed communication can be compatible.

Embodiment 4 FIG.
In the first to third embodiments described above, the first to fourth divided photoelectric converters 4, 5, 6, and 7 that are spatially divided into three are detected in order to detect the coarse capture error and the fine capture error. In the fourth embodiment, a configuration for controlling defocusing of input light to the optical hybrid element 3 is shown. In the following description, as in the first to third embodiments, an example in which the optical hybrid element 3 that generates output signals whose phases are different from each other by 90 degrees is used will be described.

  In the fourth embodiment, the beam diameter input to the acquisition tracking sensor 12 is controlled by controlling the defocusing of the input light to the hybrid element 3. Thereby, the sensitivity and dynamic range for angle detection can be changed, and both the wide angle detection function and the high-precision angle detection function can be achieved. Further, by making the wide angle detection function and the high precision angle detection function compatible, an angle detector for coarse capture becomes unnecessary, and the apparatus can be miniaturized.

FIG. 9 is a diagram illustrating a configuration example of a defocus controller of the acquisition and tracking device according to the fourth embodiment, and FIG. 10 is a reception image when the acquisition and tracking device according to the fourth embodiment detects a wide angle and detects a high-precision angle. FIG.
As shown in FIG. 9, after the incoming light 201 from the optical antenna 1 is collected by the objective lens 18a, the beam size is changed using the relay lens 18b. Here, the defocusing of the input light to the optical hybrid element 3 is controlled by changing the position of the relay lens 18b in the arrow B direction.

  By controlling the defocusing, the beam diameter of the signal light changes with respect to the local light in the acquisition and tracking sensor 12 as shown in FIG. As shown in FIG. 10A, the beam diameter of the signal light is set large when detecting a wide angle, and the beam diameter of the signal light is set small when detecting a highly accurate angle as shown in FIG. 10B.

Here, FIG. 11 shows the numerical calculation results of the detection accuracy and the dynamic range when the incoming beam diameter of the incoming light 201 is 10 [mm] and the focal length of the relay lens 18b is 250 [mm]. FIG. 11A shows an example of calculation output, and FIG. 11B shows the calculated dynamic range and measurement accuracy.
For the calculation output, the above-described equations (1) and (2) are used. The calculation output 0.5 (range that can be linearly approximated) is assumed to be the measurement range (dynamic range), and the measurement accuracy is assumed to be 8 bit DAQ as the calculation output. As shown in FIG. 11B, the dynamic range and measurement accuracy can be changed by changing the defocus value.

FIG. 12 is a diagram illustrating a configuration of the acquisition and tracking apparatus according to the fourth embodiment.
In FIG. 12, the acquisition and tracking device includes an optical antenna 1, a defocus controller 18, a local light source 2, an optical hybrid element 3, a fifth split photoelectric converter (horizontal split photoelectric converter) 19, and a sixth Capture tracking composed of a split photoelectric converter (vertical split photoelectric converter) 20, a first photoelectric converter (non-split photoelectric converter) 21, and a second photoelectric converter (non-split photoelectric converter) 22. The sensor 12 includes a first differential amplifier circuit 13, a second differential amplifier circuit 14, a Costas loop circuit 15, and a tracking control signal generation circuit 23.
In the following, the same or corresponding parts as the components of the acquisition and tracking apparatus according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof is omitted or simplified. Further, as in the first embodiment, a case where an optical 90-degree hybrid is used as the optical hybrid element 3 will be described as an example.

  The optical antenna 1 receives incoming light that propagates through space. The defocus controller 18 adjusts the defocus of the received incoming light 201. The optical hybrid element 3 is an element having a characteristic that combines the local light 202 with the incoming light whose defocus is adjusted, and in particular maintains the one-to-one relationship between the incident angle and the outgoing angle. The fifth split type photoelectric converter 19 and the sixth split type photoelectric converter 20 are Q channel ports, and the non-split type first photoelectric converter 21 and the second photoelectric converter 22 are I channel ports. .

FIG. 13 is a diagram illustrating a division pattern of a divided photoelectric converter of the acquisition and tracking device according to the fourth embodiment, and a connection of each divided photoelectric converter and each photoelectric converter.
As shown in FIG. 13, the fifth split photoelectric converter 19 has photoelectric conversion regions 19 a and 19 b arranged in the X direction (horizontal direction) with respect to the beam irradiation surface A, and the sixth split photoelectric converter 20. The photoelectric conversion regions 20a and 20b are arranged in the Y direction (vertical direction) with respect to the beam irradiation surface A. In FIG. 13, reference numerals 19c and 20c denote light receiving spots. In this way, by configuring the split photoelectric converters in an orthogonal arrangement, the X component capture error signal from the fifth split photoelectric converter 19 and the Y component of the sixth split photoelectric converter 20 are arranged. Obtain a capture error signal. Capture error signals of the fifth split photoelectric converter 19 and the sixth split photoelectric converter 20 are output to the first differential amplifier circuit 13 and the tracking control signal generation circuit 23. On the other hand, the output signals of the first photoelectric converter 21 provided with the light receiving spot 21 a and the second photoelectric converter 22 provided with the light receiving spot 22 a are output to the second differential amplifier circuit 14.

  The tracking control signal generation circuit 23 uses the optical antenna control signal (212) and the defocus control signal (213) based on the correction error signals of the fifth split photoelectric converter 19 and the sixth split photoelectric converter 20. Is output to the optical antenna 1 and the defocus controller 18 as a feedback signal. As a result, the generated feedback signal is fed back to the acquisition and tracking sensor 12.

  The first differential amplifier circuit 13 and the second differential amplifier circuit 14 remove light source noise from the local light source 2, and output an I channel signal and a Q channel signal that are 90 degrees out of phase, respectively. By inputting these into the Costas loop circuit 15 and feeding back the frequency error signal to the local light source 2, phase synchronization between the incoming light 201 and the local light 202 is established.

Next, a signal output example and the processing operation of the defocus controller 18 will be described.
FIG. 14 is a diagram illustrating an example of signal output from each split photoelectric converter when the arrival angle of the incoming light changes.
FIG. 15 is a flowchart showing the operation until the tracking completion of the acquisition and tracking device according to the fourth embodiment.
When the optical antenna 1 receives incoming light (step ST1), the acquisition and tracking device determines whether or not the calculation output is outside the threshold (step ST2). The process of step ST2 is executed, for example, on a program or in an analog circuit, and it is determined whether the calculation output signal voltage is outside the threshold value.

When it is determined that the calculation output is outside the threshold (step ST2; YES), the process proceeds to step ST5. On the other hand, when it is determined that the calculation output is within the threshold (step ST2; NO), the defocus controller 18 determines whether or not the defocus value is outside the threshold (step ST3). When it is determined that the defocus value is outside the threshold (step ST3; YES), the defocus controller 18 performs defocus control (step ST4). Thereafter, the process returns to the determination process of step ST3. On the other hand, when it is determined that the defocus value is within the threshold value (step ST3; NO), for example, pointing control for controlling the angle of the propagating light by controlling the angle of the adaptive mirror using an adaptive mirror pair or the like. (Step ST5), and the process ends.

  As described above, according to the fourth embodiment, the defocus controller 18 that adjusts the defocus of the incoming light, the optical hybrid element 3 that generates output signals whose phases are different from each other by 90 degrees, and the spatial The output signals from the fifth divided photoelectric converter 19 and the sixth divided photoelectric converter 20 divided into two and the non-divided first photoelectric converter 21 and the second photoelectric converter 22 are used. Therefore, the fifth and sixth split photoelectric converters 19 and 20 and the first and second photoelectric converters 21 and 22 perform optical heterodyne detection, respectively, so that the wide angle range is obtained. It is possible to achieve both the angle detection function and the highly accurate angle error detection function. In addition, both angle detection in a wide angle range and high-speed communication can be achieved, and the required transmission power can be reduced. Further, by making the wide angle detection function and the high precision angle detection function compatible, an angle detector for coarse capture becomes unnecessary, and the apparatus can be miniaturized.

  In the first embodiment described above, a description has been given assuming that optical 90-degree hybrid is used for the optical hybrid element 3 and optical homodyne communication is performed, but the present invention is limited to the communication method and optical 90-degree hybrid described above. For example, the present invention can also be applied to the case where two output ports of an optical 180-degree hybrid having an incident angle and an emission angle in a one-to-one relationship are used as the optical hybrid element 3.

Embodiment 5. FIG.
In the first to fourth embodiments described above, the angle detection of the arrival angle 201 when the propagation angle of the local light 202 is assumed to be stable has been described. A configuration is shown in which modulation is applied and the propagation angle of local light 202 and the propagation angle of signal light can be detected simultaneously.
When the propagation angle of the local light 202 changes, even if the arrival angle of the signal light does not change, the calculation output of the split photoelectric converter changes, resulting in a surplus error. Therefore, when performing highly accurate angle detection, it is necessary to detect and control the propagation angle of the local light 202.

  FIG. 16 is a diagram illustrating a configuration of the acquisition and tracking apparatus according to the fifth embodiment. Instead of the first photoelectric converter 21 and the second photoelectric converter 22 of the acquisition and tracking device shown in the fourth embodiment, a seventh divided photoelectric converter (horizontal divided photoelectric converter) 30 and an eighth photoelectric converter are used. The split type photoelectric converter (vertical split type photoelectric converter) 31 is provided. Further, an optical phase modulator 26, an angle correction unit 27, a frequency discrimination circuit 28, and a propagation angle control signal generation circuit 29 are additionally provided.

  The optical phase modulator 26 is provided in a local light emission path that is a subsequent stage of the local light source 2 and modulates the phase of the local light output from the local light source 2. The angle correction unit 27 is configured by, for example, an adaptive mirror and controls the propagation angle of local light output from the phase modulator 26. The frequency discriminating circuit 28 is a circuit that discriminates and cuts out the local light emission signal from the received signal. Further, the angle error of local light is detected using the extracted signal. The propagation angle control signal generation circuit 29 is a control circuit that generates a propagation angle control signal (214) based on the angle error of local light detected by the frequency discrimination circuit.

FIG. 17 is a diagram illustrating a division pattern of the division type photoelectric converter of the acquisition and tracking device according to the fifth embodiment and a connection of each division type photoelectric converter.
The fifth split photoelectric converter 19 and the sixth split photoelectric converter 20 are Q channel ports, and the seventh photoelectric converter 30 and the eighth photoelectric converter 31 are I channel ports. In the fifth embodiment, the I channel port is not a non-divided type but a divided type photoelectric converter, and is used for detecting an angular error of local light.

  The division pattern and the arrangement direction of the fifth divided photoelectric converter 19 and the sixth divided photoelectric converter 20 are the same as those in the fourth embodiment. On the other hand, the seventh divided photoelectric converter 30 has the photoelectric conversion regions 30a and 30b arranged in the X direction (horizontal direction) with respect to the beam irradiation surface A, and the eighth divided photoelectric converter 31 has the photoelectric conversion region 31a. , 31b are arranged in the Y direction (vertical direction) with respect to the beam irradiation surface A. In FIG. 17, 30c and 31c indicate light receiving spots. In this way, by configuring the seventh divided photoelectric converter 30 and the eighth divided photoelectric converter 31 in an orthogonal arrangement, the X component capture error signal from the seventh divided photoelectric converter 30 and the The Y component capture error signal is acquired from the eighth split type photoelectric converter 31. Capture error signals of the seventh split photoelectric converter 30 and the eighth split photoelectric converter 31 are output to the second differential amplifier circuit 14 and the frequency discrimination circuit 28.

  The frequency discriminating circuit 28 performs down-conversion using the same signal as the signal applied to the phase modulator 26 in the local light emission path, and detects an angular error of local light. The detected angle error signal is input to the propagation angle control signal generation circuit 29 to generate a propagation angle control signal and fed back to the angle correction unit 27.

FIG. 18 is a diagram showing the configuration of the frequency discrimination circuit of the acquisition and tracking device according to the fifth embodiment, and FIG.
A signal by local light phase modulation (f _L ) other than the communication signal component (f _s ) is extracted by a bandpass filter 28a that is an electric filter, and a signal by local light phase modulation (f _L ) is extracted by the multiplier 28b. Multiply and downconvert. As a result, the DC current changes depending on the amount of light received by the local light, and the angular error of the local light can be detected. The propagation angle control signal generated by the propagation angle control signal generation circuit 29 based on the detected angle error signal is fed back to the angle correction unit 27, so that the propagation angle of local light emission can be stabilized.

FIG. 20 is a flowchart showing the operation of the acquisition and tracking apparatus according to the fifth embodiment.
First, the acquisition and tracking device sets the local light emission pointing (step ST11), and sets the signal light pointing and the defocus value (step ST12). Here, the process of step ST11 is performed using an adaptive mirror or the like, and the process of step ST12 is executed on a program or in an analog circuit, for example. Thereafter, when the optical antenna 1 receives incoming light (step ST13), it is determined whether or not the calculation output of local light is outside the threshold (step ST14). If it is determined that the local light calculation output is outside the threshold (step ST14; YES), the process returns to step ST11 to reset the local light pointing. On the other hand, when it is determined that the calculation output of local light is within the threshold (step ST14; NO), it is determined whether the calculation output of the signal light is outside the threshold (step ST15). When it is determined that the calculation output of the signal light is outside the threshold (step S15; YES), the processing returns to step ST12 to reset the pointing of the signal light.

  On the other hand, when it is determined that the calculation output of the signal light is within the threshold (step ST15; NO), it is determined whether the defocus value of the signal light is outside the threshold (step ST16). When it is determined that the defocus value of the signal light is outside the threshold (step ST16; YES), the process returns to step ST12, and the defocus value of the signal light is reset. On the other hand, when it is determined that the defocus value of the signal light is within the threshold (step ST16; NO), the process is terminated.

  As described above, according to the fifth embodiment, the defocus controller 18 that adjusts the defocus of the incoming light, the optical hybrid element 3 that generates output signals whose phases are different from each other by 90 degrees, and the local light emission. An acquisition and tracking sensor configured to control an optical axis of local light, which includes an optical phase modulator 26 for providing phase modulation and spatially divided fifth to eighth divided photoelectric converters 19, 20, 21, and 22. 12, a frequency discriminating circuit 28 that extracts a local light modulation signal after photoelectric conversion, and an angle correction unit 27 that detects the propagation angle of the local light from the extracted local light modulation signal. By detecting the angle error of the light emission, the angle detection error of the signal light due to the propagation angle error of the local light can be reduced, and high accuracy of the angle detection mechanism can be realized.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Optical antenna, 2 local light source, 3 optical hybrid element, 4 1st division | segmentation type photoelectric converter 4a, 4b, 4c, 5a, 5b, 5c, 6a, 6b, 6c, 7a, 7b, 7c, 19a, 19b, 20a, 20b, 30a, 30b, 31a, 31b Photoelectric conversion region, 4d, 5d, 6d, 7d, 19c, 20c, 21a, 22a, 30c, 31c Light receiving spot, 5 Second split photoelectric converter, 6 3rd division type photoelectric converter, 7 4th division type photoelectric converter, 8 1st coarse acquisition error signal generation circuit, 9 1st fine acquisition error signal generation circuit, 10 2nd coarse acquisition error signal generation Circuit, 11 second fine acquisition error signal generation circuit, 12 acquisition tracking sensor, 13 first differential amplification circuit, 14 second differential amplification circuit, 15 Costas loop circuit, 16 coarse acquisition control signal generation circuit, 17Capture control signal generation circuit, 18 defocus controller, 18a objective lens, 18b relay lens, 19 fifth split photoelectric converter, 20 sixth split photoelectric converter, 21 first photoelectric converter 21, 22 Second photoelectric converter, 23 tracking control signal generation circuit, 26 optical phase modulator, 27 local emission angle correction mechanism, 28 frequency discrimination circuit, 28a band pass filter, 28b multiplier, 29 local emission propagation angle control signal generation circuit , 30 Seventh split type photoelectric converter, 31 Eighth split type photoelectric converter, 01 Arrival light, 202 Local light, 203 1/2 wavelength plate, 204 1/4 wavelength plate, 205 Beam splitter, 206, 207 Polarization splitting splitter, 208, 209, 210, 211, 208 ′, 209 ′, 210 ′, 211 ′ output signal, 212 optical antenna control signal, 13 defocus control signals, 214 propagation angle control signal.

Claims (5)

An optical antenna for receiving spatially propagating laser light;
A local light source that outputs local light having substantially the same wavelength as the received light of the optical antenna;
A hybrid device that combines the received light and the local light with a light wave, and outputs a plurality of outgoing lights having an outgoing angle equal to an incident angle of the received light;
A photoelectric conversion unit that converts a plurality of emission lights output from the hybrid element into detection signals, and a coarse acquisition error signal that captures the detection signals converted by the photoelectric conversion unit at a wide angle with respect to the emission surface of the hybrid element A capture tracking sensor comprising: a coarse capture tracking mechanism that generates a fine capture error signal that captures the detection signal converted by the photoelectric conversion unit with high accuracy in the emission direction of the hybrid element ; ,
A coarse correction control signal generation circuit for generating a coarse acquisition control signal for driving the coarse acquisition tracking mechanism using the coarse acquisition error signal generated by the acquisition and tracking sensor;
A fine capture control signal generating circuit for generating a fine capture control signal for driving the fine capture and tracking mechanism using the fine capture error signal generated by the capture and tracking sensor;
A phase synchronization control circuit that generates a frequency error signal based on the detection signal converted by the photoelectric converter and outputs a feedback to the local light source ,
The photoelectric conversion unit includes first and second photoelectric conversion regions that are divided into two in the horizontal direction with respect to the emission surface of the receiving element, and a third photoelectric conversion that is in contact with the first and second photoelectric conversion regions. A horizontal photoelectric converter having a region, first and second photoelectric conversion regions that are divided into two in a direction perpendicular to the emission surface of the receiving element, and a third that is in contact with the first and second photoelectric conversion regions A plurality of vertical photoelectric converters having a photoelectric conversion region of
The coarse acquisition tracking mechanism uses a detection signal output from the third photoelectric conversion region of the horizontal photoelectric converter and the third photoelectric conversion region of the vertical photoelectric converter as a rough acquisition error, A coarse capture error signal is generated, and the fine capture tracking mechanism is output from the first and second photoelectric conversion regions of the horizontal photoelectric converter and the first and second photoelectric conversion regions of the vertical photoelectric converter. A capture tracking device that generates the fine capture error signal from a tracking error calculated by performing a centroid operation on a detection signal . The hybrid element combines input received light and local light with a 90-degree phase difference hybrid, and outputs two I-channel output ports that output emitted light with a phase difference of 0 degree and a phase difference of 180 degrees, and a phase difference of 90 Two Q channel output ports for outputting outgoing light having a phase difference of 270 degrees and a phase difference of 270 degrees,
In the photoelectric conversion unit, two horizontal photoelectric converters and two vertical photoelectric converters that convert light emitted from either of the two I channel output ports and the two Q channel output ports into detection signals are arranged orthogonally. The acquisition and tracking device according to claim 1 . The photoelectric conversion unit includes the horizontal photoelectric converter and the vertical photoelectric converter connected to the two I channel output ports, and the horizontal photoelectric converter and the vertical photoelectric converter connected to the two Q channel output ports. The transducer is placed orthogonally,
The coarse acquisition tracking mechanism is a tracking calculated using detection signals output from the first and second photoelectric conversion regions of the horizontal photoelectric converter and the vertical photoelectric converter to which the Q channel output port is connected. acquisition and tracking apparatus according to claim 2, wherein the generating the fine acquisition error signal from the error. The photoelectric conversion unit includes the horizontal photoelectric converter and the vertical photoelectric converter connected to the two I channel output ports, and the horizontal photoelectric converter and the vertical photoelectric converter connected to the two Q channel output ports. The transducer is placed orthogonally,
The coarse acquisition and tracking mechanism includes a detection signal output from the first and second photoelectric conversion regions of the horizontal photoelectric converter to which the I channel output port is connected, and the vertical to which the Q channel output port is connected. 3. The acquisition and tracking device according to claim 2, wherein the fine acquisition error signal is generated from a tracking error calculated using detection signals output from the first and second photoelectric conversion regions of the photoelectric converter. The acquisition and tracking device according to claim 3 , wherein the hybrid element makes the output of the I channel output port larger than the output of the Q channel output port.

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