Space laser communication optical axis control device and method

Abstract

The application provides a space laser communication optical axis control device and method, which utilizes a photoelectric detector and a fast mirror 1 in a first-stage fine tracking loop, utilizes a nutation assembly and a fast mirror 2 in a second-stage fine tracking loop, and corrects the tracking zero of the first-stage fine tracking loop according to the bias of the second-stage fast mirror. The application is applied to space laser communication, and the cooperation of the two-stage fine tracking loops makes the beam control system have the advantages of being capable of inhibiting beam jitter caused by high frequency and strong vibration, and being capable of compensating the deviation between the communication optical axis and the tracking optical axis in real time.

Description

Technical Field

[0001] The invention belongs to the field of optical equipment technology, specifically relating to a space laser communication optical axis control device and method. Background Technology

[0002] my country is prioritizing satellite internet development as part of its new infrastructure initiatives, steadily advancing satellite constellation networking. A crucial element of this networking is the establishment and maintenance of inter-satellite communication links. Inter-satellite communication links can be implemented using either microwave or laser communication. Compared to microwave communication, laser communication offers unique advantages: lower power consumption, higher data rates, smaller size, no spectrum resource limitations, and better security. Laser communication links will become an indispensable component of satellite constellations.

[0003] To achieve inter-satellite laser communication, a link needs to be established and maintained first through a scanning acquisition and tracking device, that is, to efficiently couple space light into optical fiber, and then modulate and demodulate the optical signal. The laser communication link is affected by micro-vibrations and thermal deformation of the satellite platform, leading to a decrease in the coupling efficiency of space light to the optical fiber. Existing conventional solutions use a single-stage precision tracking device to control the optical axis; however, this design is limited by the limited bandwidth of the precision tracking loop. In strong space vibration environments, the coupling efficiency of space light to the optical fiber decreases. Furthermore, due to the separate design of the tracking axis and communication axis, the optical system is subject to thermal deformation caused by the periodic effects of the space thermal environment, resulting in non-coaxiality between the tracking axis and communication axis during long-term communication link maintenance. To solve the problem of limited bandwidth in the single-stage precision tracking loop…

[0004] High-speed free-space optical communication using standard fiber communication components without optical amplification[J].Advanced PhotonicsNexus, 2023, 2(6):065001.DOI:10.1117 / 1.APN.2.6.065001 introduces a two-stage precision tracking device, but this design scheme fails to solve the problem of non-coaxiality between the tracking optical axis and the communication optical axis caused by thermal deformation of the optical system. On March 29, 2024, the Beijing Remote Sensing Equipment Research Institute applied for and obtained the patent with authorization announcement number CN114389683B, which introduces a method for on-orbit autonomous correction of the optimal tracking point of the communication detector. However, this method fails to solve the problem of separation between the tracking axis and the communication axis, and the method actively causes a decrease in signal optical coupling power during the scanning process, increasing the risk of communication link termination. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a space laser communication optical axis control device. It utilizes a first-stage fine tracking loop with a photodetector and a fast reflector 1, and a second-stage fine tracking loop with a nutation component and a fast reflector. Simultaneously, the tracking zero position of the first-stage fine tracking loop is corrected based on the offset of the second-stage fast reflector. This invention is applied to space laser communication. The combination of the two-stage fine tracking loops enables this beam control system to suppress beam jitter caused by high-frequency, strong vibrations. Furthermore, it offers the advantage of real-time compensation for the deviation between the communication optical axis and the tracking optical axis.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, the present invention provides a space laser communication optical axis control device, characterized in that it includes a first-stage fine tracking loop, a second-stage fine tracking loop, and a signal processing and control board;

[0008] The first-stage fine tracking loop includes a signal light that is reflected by a first fast reflector and reaches a beam splitter. After being reflected by the beam splitter, the light is focused into a light spot 1 by a first lens group on a first photodetector.

[0009] The second-stage fine tracking loop includes the signal light being reflected by the first fast reflector and reaching the beam splitter. After being transmitted through the beam splitter, it passes through the second fast reflector and is focused into a light spot 2 on the nutation component by the second lens group. The spatial light is coupled into the optical fiber, and then part of the light enters the second photodetector through the optical fiber beam splitter.

[0010] The signal processing and control board is electrically connected to the first fast reflector, the first photodetector, the second fast reflector, the nutation assembly, and the second photodetector, respectively.

[0011] By adjusting the positions of the beam splitter, the first photodetector, the second fast reflector, and the nutation assembly, the initial zero position of the light spots on the first and second photodetectors, as well as the initial zero position driving voltage values ​​of the first and second fast reflectors, are set.

[0012] The driving voltage values ​​are all output by the signal processing and control board, and the spot positions are all processed and analyzed by the signal processing and control board.

[0013] On the other hand, the present invention also provides a control method for the above-mentioned space laser communication optical axis control device, characterized in that it includes the following steps:

[0014] S1. Determine the initial zero position of the light spot 1 on the first photodetector and the initial zero position driving voltage value of the first fast reflector; determine the initial zero position of the light spot 2 on the nutation assembly and the initial zero position driving voltage value of the second fast reflector.

[0015] S2. After the signal light is reflected by the first fast reflector and the beam splitter, it is focused into a light spot 1 on the first photodetector by the first lens group. The signal processing and control board obtains the current position of the light spot 1 and calculates the position deviation of the light spot 1 based on the initial zero position of the light spot 1 on the first photodetector.

[0016] S3. Based on the position deviation of spot 1 obtained in step S2, adjust the first fast reflecting mirror so that the position of spot 1 converges to the initial zero position of spot 1.

[0017] S4. Control the nutation component to swing along a specific trajectory, preferably a circular trajectory, and optionally a cross-shaped trajectory;

[0018] S5. The signal light is reflected by the first fast reflector and reaches the beam splitter. After being transmitted through the beam splitter, it passes through the second fast reflector and is focused into a light spot 2 on the nutation assembly by the second lens group. Then, part of the light enters the second photodetector through the fiber beam splitter. The signal processing and control board obtains the current position of the light spot 2 and calculates the position deviation of the light spot 2 based on the initial zero position of the light spot 2 on the nutation assembly.

[0019] S6. Based on the position deviation of spot 2 obtained in step S5, adjust the second fast reflector so that the position of spot 2 converges to the initial zero position of spot 2;

[0020] S7. Slide the average driving voltage of the second fast reflector and calculate the deviation between the average driving voltage of the second fast reflector and the initial zero driving voltage value of the second fast reflector. When the deviation is greater than a set threshold, correct the zero value of the light spot 1 on the first photodetector.

[0021] S8. Repeat steps S2-S3 to bring the position of spot 1 to the corrected zero value of spot 1 until the entire workflow is terminated.

[0022] Furthermore, in step S7, the deviation between the average value of the driving voltage of the second fast reflector and the initial zero-position driving voltage value of the second fast reflector is calculated. The formula is as follows:

[0023]

[0024]

[0025] In the formula, The average value of the X-axis driving voltage of the second fast mirror is calculated for the nth sliding motion. The average value of the Y-axis driving voltage of the second fast mirror is calculated for the nth sliding motion. This represents the zero-position drive voltage value along the X-axis of the second fast-reflecting mirror. This is the zero-position drive voltage value of the Y-axis for the second fast reflector;

[0026] In step S7, the zero-position value of spot 1 on the first photodetector is corrected using the following formula:

[0027] +

[0028] In the formula, A is the transformation matrix from the deviation of the second fast reflector driving voltage to the zero-position correction of spot 1, and Xt 1(m-1) The x-axis coordinate value of the zero position of spot 1 after m-1 corrections, Yt 1(m-1) Xt1 is the zero-position Y-axis coordinate value of spot 1 after m-1 corrections, Xt1 is the zero-position X-axis coordinate value of spot 1 after m-1 corrections, and Yt1 is the zero-position Y-axis coordinate value of spot 1 after m-1 corrections.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The two-stage fine tracking loop proposed in this invention not only improves the beam disturbance suppression capability of the entire beam control system, but also solves the problem of real-time compensation of the communication optical axis and the tracking optical axis, ensuring the long-term maintenance of the space laser communication link.

[0030] By precisely controlling each component in the optical path, precise control of the laser communication optical axis is achieved, thereby ensuring the stability and efficiency of communication. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the space laser communication optical axis control device of the present invention.

[0032] Figure 2 The flowchart is of the control method of the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0034] Please see Figure 1 , Figure 1The figure shows a schematic diagram of the optical axis control device for space laser communication according to the present invention. The device includes a signal processing and control board 1, a first fast reflector 2, a beam splitter 3, a first lens group 4, a first photodetector 5, a second fast reflector 6, a second lens 7, a nutation assembly 8, an optical fiber beam splitter 9, and a second photodetector 10. Incident light is reflected by the first fast reflector 2 and reaches the beam splitter 3. A portion of the light is reflected by the beam splitter 3 and converged by the first lens group 4 before illuminating the first photodetector 5. Another portion of the light is transmitted through the beam splitter 3, passing through the second fast reflector 6 and the second lens group 7, converging at the nutation assembly 8, and then through the optical fiber beam splitter 9. A portion of the light enters the second photodetector 10. The first fast reflector 2, the first photodetector 5, the second fast reflector 6, the nutation assembly 8, and the second photodetector 10 are all electrically connected to the signal processing and control board 1.

[0035] During assembly and adjustment, the space laser communication optical axis control system adjusts the beam splitter 3, the first photodetector 5, the second fast reflector 6, and the nutation assembly 8. The initial zero position of the light spot 1 on the first photodetector is (Xt). 11 Yt 11 ), where Xt 11 Yt represents the initial zero-position X-axis coordinate value of spot 1 on the first photodetector. 11 Let be the initial zero-position Y-axis coordinate value of spot 1 on the first photodetector; at this time, the initial zero-position driving voltage value of the first fast reflector is (FVXt). 11 ,FVYt 11 ), where FVXt 11 FVYt represents the initial zero-position driving voltage value of the first fast reflector along the X-axis. 11 This is the initial zero-position driving voltage value of the Y-axis of the first fast-reflecting mirror; at this time, the zero position of the light spot 2 on the nutation component is (Xt). 21 Yt 21 ), where Xt 21 Yt represents the zero-position X-axis coordinate of spot 2 on the nutation component. 21 This represents the zero-position Y-axis coordinate value of light spot 2 on the nutation component; at this time, the zero-position driving voltage value of the second fast reflector is (FVXt). 21 ,FVYt 21 ), where FVXt 21 FVYt is the zero-position drive voltage value of the second fast reflector along the X-axis. 21 This refers to the zero-position drive voltage value of the Y-axis for the second fast reflector. All the drive voltage values ​​mentioned above are output by the signal processing and control board, and the light spot positions are processed and analyzed by the signal processing and control board.

[0036] Based on the structure of the aforementioned space laser communication optical axis control system, the control method of this system is now described, such as... Figure 2 As shown, the specific implementation steps are as follows:

[0037] Step 1: Set the initial zero-position voltage value (FVXt) of the first fast reflector on the signal processing and control board. 11 ,FVYt 11 ), where FVXt 11 FVYt represents the initial zero-position driving voltage value of the first fast reflector along the X-axis. 11 The initial zero-position driving voltage value of the first fast reflector along the Y-axis; the zero-position driving voltage value of the second fast reflector (FVXt) 21 ,FVYt 21 ), of which FVX 21 FVY is the zero-position drive voltage value of the second fast reflector along the X-axis. 21 This is the zero-position drive voltage value of the Y-axis for the second fast reflector;

[0038] Step 2: After the signal light is reflected by the first fast reflector and the beam splitter, it is focused into spot 1 on the first photodetector by the first lens group. The signal processing and control board calculates the current coordinate value of spot 1.

[0039] Step 3: The signal processing and control board calculates the current coordinates of spot 1 and the initial zero position (Xt). 11 Yt 11 ) Calculate the position deviation of spot 1, where Xt 11 Yt represents the initial zero-position X-axis coordinate value of spot 1 on the first photodetector. 11 The initial zero-position Y-axis coordinate value of spot 1 on the first photodetector;

[0040] Step 4: The signal processing and control board calculates the control signal for the first fast reflector based on the position deviation of spot 1 in Step 3, and outputs it to the first fast reflector, so that the position of spot 1 converges to the initial zero position (Xt). 11 Yt 11 ), where Xt 11 Yt represents the initial zero-position X-axis coordinate value of spot 1 on the first photodetector. 11 The initial zero-position Y-axis coordinate value of spot 1 on the first photodetector;

[0041] Step 5: The signal processing and control board controls the nutation component to swing along a specific trajectory. The preferred swing trajectory is circular, and the optional swing trajectory is cross-shaped.

[0042] Step 6: After the signal light passes through the first fast reflector, beam splitter, and second fast reflector, it is focused into spot 2 on the nutation assembly by the first lens group. At this time, the spatial light is coupled into the optical fiber, and then part of the light enters the second photodetector through the optical fiber beam splitter. The signal processing and control board calculates the current position coordinates of spot 2. , ),in To calculate the X-axis coordinate of spot 2 for the kth calculation, The Y-axis coordinate value of the position of spot 2 is calculated for the kth time;

[0043] Step 7: The signal processing and control board calculates the current coordinates of spot 2 ( , ) and initial zero (Xt) 21 Yt 21 ), calculate the position deviation of spot 2 ( , ), where Xt 21 Yt represents the initial zero-position X-axis coordinate value of spot 2 on the nutation component. 21 This represents the initial zero-position Y-axis coordinate value of spot 2 on the nutation component. For the k-th calculation of the X-axis deviation of spot 2, The formula for calculating the Y-axis deviation of spot 2 position in the k-th calculation is as follows:

[0044]

[0045]

[0046] Step 8: The signal processing and control board calculates the control signal for the second fast reflector based on the position deviation of spot 2 in Step 7, and outputs it to the second fast reflector, so that the position of spot 2 converges to zero (Xt). 21 Yt 21 ), where Xt 21 Yt represents the zero-position X-axis coordinate of spot 2 on the nutation component. 21 This represents the zero-position Y-axis coordinate value of spot 2 on the nutation component;

[0047] Step 9: The average value of the driving voltage of the second fast reflector is calculated by sliding the signal processing and control board. , ),in The average value of the X-axis driving voltage of the second fast mirror is calculated for the nth sliding motion. The average value of the Y-axis driving voltage of the second fast mirror is calculated for the nth sliding motion.

[0048] Step 10: The signal processing and control board calculates the deviation between the average value of the second fast reflector driving voltage calculated in Step 9 and the zero-position driving voltage value of the second fast reflector. , ),in This represents the deviation between the average value of the X-axis driving voltage of the second fast reflector and the zero-position driving voltage value. The deviation between the average value of the Y-axis driving voltage of the second fast reflector and the zero-position driving voltage value is calculated using the following formula:

[0049]

[0050]

[0051] in The average value of the X-axis driving voltage of the second fast mirror is calculated for the nth sliding motion. FVX is the average value of the Y-axis driving voltage of the second fast mirror calculated for the nth sliding motion. 21 FVY is the zero-position drive voltage value of the second fast reflector along the X-axis. 21 This is the zero-position drive voltage value of the Y-axis for the second fast reflector;

[0052] Step 11: When the deviation of the second fast reflector driving voltage obtained in step 10 is greater than the threshold, the zero-position value of spot 1 on the first photodetector is corrected to (Xt). 1m Yt 1m ), where Xt 1m Yt represents the zero-position X-axis coordinate of spot 1 after the m-th correction. 11 The zero-position Y-axis coordinate value of spot 1 after the m-th correction is given by the following formula:

[0053] +

[0054] Where A is the conversion matrix from the deviation of the second fast reflector driving voltage to the zero-position correction of spot 1, Xt 1（m-1） Yt represents the X-axis coordinate of the zero position of spot 1 after the (m-1)th correction. 11 This represents the Y-axis coordinate value of the zero position of spot 1 after the (m-1)th correction.

[0055] Step 12: Execute steps 2-4 to make the position of spot 1 converge to the corrected zero value.

Claims

1. A control method for a space laser communication optical axis control device, the space laser communication optical axis control device comprising a first-stage fine tracking loop, a second-stage fine tracking loop, and a signal processing and control board; The first-stage fine tracking loop includes a signal light that is reflected by a first fast reflector and reaches a beam splitter. After being reflected by the beam splitter, the light is focused into a light spot 1 by a first lens group on a first photodetector. The second-stage fine tracking loop includes the signal light being reflected by the first fast reflector and reaching the beam splitter. After being transmitted through the beam splitter, it passes through the second fast reflector and is focused into a light spot 2 on the nutation component by the second lens group. The spatial light is coupled into the optical fiber, and then part of the light enters the second photodetector through the optical fiber beam splitter. The signal processing and control board is electrically connected to the first fast reflector, the first photodetector, the second fast reflector, the nutation assembly, and the second photodetector, respectively. By adjusting the positions of the beam splitter, the first photodetector, the second fast reflector, and the nutation assembly, the initial zero position of the light spots on the first and second photodetectors, as well as the initial zero position driving voltage values ​​of the first and second fast reflectors, are set. The driving voltage values ​​are all output by the signal processing and control board, and the spot positions are all processed and analyzed by the signal processing and control board; characterized by including the following steps: S1. Determine the initial zero position of the light spot 1 on the first photodetector and the initial zero position driving voltage value of the first fast reflector; determine the initial zero position of the light spot 2 on the nutation assembly and the initial zero position driving voltage value of the second fast reflector. S2. After the signal light is reflected by the first fast reflector and the beam splitter, it is focused into a light spot 1 on the first photodetector by the first lens group. The signal processing and control board obtains the current position of the light spot 1 and calculates the position deviation of the light spot 1 based on the initial zero position of the light spot 1 on the first photodetector. S3. Based on the position deviation of spot 1 obtained in step S2, adjust the first fast reflecting mirror so that the position of spot 1 converges to the initial zero position of spot 1. S4. Control the nutation component to swing along a specific trajectory, which is either circular or cross-shaped; S5. The signal light is reflected by the first fast reflector and reaches the beam splitter. After being transmitted through the beam splitter, it passes through the second fast reflector and is focused into a light spot 2 on the nutation assembly by the second lens group. Then, part of the light enters the second photodetector through the fiber beam splitter. The signal processing and control board obtains the current position of the light spot 2 and calculates the position deviation of the light spot 2 based on the initial zero position of the light spot 2 on the nutation assembly. S6. Based on the position deviation of spot 2 obtained in step S5, adjust the second fast reflecting mirror so that the position of spot 2 converges to the initial zero position of spot 2; S7. Slide the average driving voltage of the second fast reflector and calculate the deviation between the average driving voltage of the second fast reflector and the initial zero driving voltage value of the second fast reflector. When the deviation is greater than a set threshold, correct the zero value of the light spot 1 on the first photodetector. S8. Repeat steps S2-S3 to bring the position of spot 1 to the corrected zero value of spot 1 until the entire workflow is terminated.

2. The control method of the space laser communication optical axis control device according to claim 1, characterized in that, In step S7, the deviation between the average driving voltage of the second fast reflector and the initial zero-position driving voltage value of the second fast reflector is calculated. The formula is as follows: In the formula, The average value of the X-axis driving voltage of the second fast mirror is calculated for the nth sliding motion. The average value of the Y-axis driving voltage of the second fast mirror is calculated for the nth sliding motion. This represents the initial zero-position drive voltage value along the X-axis of the second fast reflector. This is the initial zero-position drive voltage value of the second fast reflector along the Y-axis; In step S7, the zero-position value of spot 1 on the first photodetector is corrected using the following formula: + In the formula, A is the transformation matrix from the deviation of the second fast reflector driving voltage to the zero-position correction of spot 1, and Xt 1(m-1) The x-axis coordinate value of the zero position of spot 1 after m-1 corrections, Yt 1(m-1) Xt1 is the zero-position Y-axis coordinate value of spot 1 after m-1 corrections, Xt1 is the zero-position X-axis coordinate value of spot 1 after m-1 corrections, and Yt1 is the zero-position Y-axis coordinate value of spot 1 after m-1 corrections.

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