In-orbit real-time optical axis self-calibration device and method for laser communication based on corner cube prism

Abstract

The application discloses an on-orbit real-time optical axis self-calibration device and method based on a laser communication corner cube prism, and belongs to the technical field of optical communication equipment. 12 13 23 The three dihedral angles of the special corner cube prism are represented as θ 12 , θ 13 , θ 23 , and the angles are designed to be unequal to 90°, so that one parallel light beam is reflected to form six parallel outgoing light beams after being incident; the included angle between each outgoing light beam and the incident light beam is referred to as a light beam deflection angle; the greater the deviation of the dihedral angle of the special corner cube prism from 90°, the greater the light beam deflection angle; and the optical elements compose a signal emission light path, a receiving light path and a signal emission self-calibration light path. The application can realize the on-orbit real-time optical axis self-calibration of a satellite-borne laser communication terminal without increasing additional self-calibration branches and devices.

Description

Technical Field

[0001] This invention belongs to the field of optical communication equipment technology, specifically relating to a laser communication on-orbit real-time optical axis self-calibration device and method based on a cornerstone prism. Background Technology

[0002] In the field of spaceborne laser communication, the optical axes of the signal transmission, signal reception, and tracking reception paths of the communication terminal must remain parallel. As communication distances increase, to ensure sufficient power margin in the communication link, the signal divergence angle must be reduced to tens of microradians, and the parallelism of each optical path must be within ten microradians. Because spaceborne laser communication terminals are subjected to vibration and impact during transportation, transmission, and on-orbit operation, the parallelism between the optical axes is severely affected. Therefore, on-orbit calibration of the parallelism of each optical path is crucial.

[0003] Chinese patent application CN201811554230 proposes an on-orbit calibration and coaxiality correction device and method for satellite optical communication terminals. It uses conventional pyramids and external calibration transmission branches, internal signal calibration transmission branches, internal beacon calibration transmission branches, and calibration reflectors to calibrate the signal transmission optical path, signal reception optical path, and beacon reception optical path. The limitation of this patent is that it adds multiple branches for calibration and compensation, making the method complex, and calibration and communication require time-division multiplexing, preventing simultaneous operation. Chinese patent application CN201810945384 proposes an optical axis self-calibration device and method for optical communication systems. It uses conventional pyramids and dual-core optical fibers (for transmission and self-calibration) to calibrate the transmission optical path without adding extra branches, but it also requires communication interruption and cannot perform real-time self-calibration of the optical axis during communication. The limitation of using a conventional cone is that the outgoing beam is parallel to the incident beam. Therefore, when the optical axes of each branch are coaxial, the self-calibrated spot coincides with or is very close to the beacon receiving spot, making it impossible to distinguish and difficult to process. It requires time-division processing of beacon receiving and self-calibration, and cannot achieve real-time on-orbit calibration (self-calibration of the optical axis is carried out simultaneously during normal communication).

[0004] In summary, the currently available laser communication self-calibration methods have limitations and none of them have on-orbit real-time calibration capabilities. Therefore, it is an important problem that needs to be solved by those skilled in the art to research a laser communication self-calibration device and method with on-orbit real-time calibration capabilities and a simple structure. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a real-time on-orbit optical axis self-calibration device and method for laser communication based on a cornerstone prism. Without adding additional self-calibration branches and devices, it can achieve real-time on-orbit optical axis self-calibration of the spaceborne laser communication terminal without interrupting communication, and can perform optical axis calibration of the receiving and transmitting optical paths in real time.

[0006] The above objectives are achieved through the following technical solutions:

[0007] A real-time on-orbit optical axis self-calibration device for laser communication based on a cornerstone prism includes the following optical components: a special cornerstone prism, a beam splitter, a receiving lens, a receiving detector, a signal transmitting lens, and a signal transmitting laser; the three dihedral angles of the special cornerstone prism are represented by θ. 12 θ 13 θ 23 Its angle is intentionally designed to be not equal to 90°, and its angle range satisfies the following formula: 0.03° < |θ 12 -90°| < 5°, 0.03° < |θ 13 -90°| < 5°, 0.03° < |θ 23 -90°|<5°. This causes a parallel beam of light to be reflected after incident, forming 6 parallel beams of light. The angle between each beam of light and the incident beam is called the beam deflection angle. The greater the deviation of the dihedral angle of the special corner cube prism from 90°, the greater the beam deflection angle.

[0008] The aforementioned optical components constitute signal transmission optical path one, receiving optical path one, and signal transmission self-calibration optical path one;

[0009] The signal transmission optical path includes a signal transmitting laser, a signal transmitting lens, and a beam splitter; the signal transmitting laser emits laser light, which passes through the signal transmitting lens to the rear surface of the beam splitter, and then transmits the signal outward through the beam splitter.

[0010] The receiving optical path includes a beam splitter, a receiving lens, and a receiving detector; external signals are reflected by the front surface of the beam splitter, pass through the receiving lens, and reach the receiving detector to form a receiving spot.

[0011] The signal transmission self-calibration optical path includes a signal transmitting laser, a signal transmitting lens, a receiving lens, a receiving detector, a beam splitter, and a special corner cube prism. The signal transmitting laser emits a laser beam, which passes through the signal transmitting lens to the rear surface of the beam splitter. The beam is then reflected by the rear surface of the beam splitter to the special corner cube prism. The beam is reflected back to the beam splitter by the special corner cube prism and then passes through the receiving lens to the receiving detector to form a self-calibration spot for the emitted optical axis.

[0012] The present invention also provides a method for performing real-time on-orbit optical axis self-calibration of laser communication using the above-mentioned laser communication real-time on-orbit optical axis self-calibration device based on a cornerstone prism, the method comprising the following steps:

[0013] Step 1: In a laboratory environment, calibrate the initial optical axis position of the signal transmission optical path, the signal transmission laser emits laser light, and select one of the six light spots on the receiving detector, marking the position as A1(X1, Y1).

[0014] Step 2: In a laboratory environment, mark the initial optical axis position of the receiving optical path, receive external signals, and display a light spot on the receiving detector. Mark the position A2 (X2, Y2). Due to the special corner cube prism, the coordinates of A2 are far away from the coordinates of A1.

[0015] Step 3: During system communication, the signal emitting laser emits signal light, which is collimated by the signal emitting lens and then reflected by the rear surface of the beam splitter and the special corner cube prism 1. The emitted signal light is reflected back to the beam splitter, passes through the beam splitter and the receiving lens, and is displayed as spot A1' (X1', Y1') on the window of the receiving detector. The coordinate deviation between A1' and A1 is recorded as the real-time optical axis change of the emitted light path.

[0016] Step 4: During system communication, the external laser is reflected by the beam splitter and collimated by the receiving lens. The received signal spot A2' (X2', Y2') is displayed in real time on the window of the receiving detector. The coordinate deviation between A2' and A2 is recorded as the real-time optical axis change of the receiving optical path. Due to the special corner cube prism, the coordinates of A2' are far away from the coordinates of A1'. Therefore, the communication spot and the self-calibration spot can be displayed simultaneously without affecting normal transmission and reception.

[0017] As a further improvement of the present invention, the optical element further includes an optical antenna, a second beam splitter, a fast-reflecting mirror, a signal receiving lens, a signal receiving detector, and a second fast-reflecting mirror. The signal receiving detector includes a dual-core optical fiber, with the on-axis core fiber serving as the signal receiving fiber and connected to the optoelectronic processing device, and the off-axis core fiber serving as the signal receiving self-calibration fiber and connected to a self-calibration light source. Assuming the core pitch of the dual-core optical fiber is d1, the focal length of the signal receiving lens is f1, and the focal length of the receiving lens is f2, the distance d2 between the light spot on the detector after the light emitted by the signal receiving self-calibration light source returns through the pyramid and the optical axis spot of the signal receiving optical path is given by the formula d2=f2*d1 / f1.

[0018] The optical elements constitute a signal transmitting optical path two, a receiving optical path two, a signal receiving optical path, a signal transmitting self-calibration optical path two, and a signal receiving self-calibration optical path;

[0019] The second signal transmission optical path is as follows: the signal transmitting laser emits laser light, which passes through the signal transmitting lens to the front surface of the fast reflector, is reflected by the front surface of the fast reflector to the second beam splitter, passes through the second beam splitter to the rear surface of the beam splitter, and is reflected by the beam splitter and the second fast reflector before being transmitted outward through the optical antenna.

[0020] The second receiving optical path: the external signal passes through the optical antenna, is reflected by the second fast mirror, reaches the front surface of the beam splitter, is reflected by the front surface of the beam splitter, passes through the receiving lens, and reaches the receiving detector to form a receiving spot.

[0021] The signal receiving optical path is as follows: the external signal passes through the optical antenna and is reflected by the second fast mirror, then reaches the front surface of the beam splitter, passes through the beam splitter to the front surface of the second beam splitter, is reflected by the front surface of the second beam splitter, passes through the signal receiving lens to the signal receiving detector, and is transmitted to the optoelectronic processing equipment through the on-axis core optical fiber.

[0022] The second signal emission self-calibration optical path is as follows: the signal emission laser emits a laser beam, which passes through the signal emission lens to the front surface of the fast reflector, is reflected by the front surface of the fast reflector to the second beam splitter, passes through the second beam splitter to the rear surface of the beam splitter, is reflected by the rear surface of the beam splitter to a special corner cube prism, and the beam is reflected back to the beam splitter by the special corner cube prism and passes through the receiving lens to the receiving detector to form the optical axis spot of the signal emission self-calibration optical path.

[0023] The signal receiving self-calibration optical path: the self-calibration light source emits laser light, which passes through the signal receiving lens to the front surface of the second beam splitter, is reflected by the front surface of the second beam splitter to the rear surface of the beam splitter, is reflected by the rear surface of the beam splitter to a special corner cube prism, and the beam is reflected back to the beam splitter by the special corner cube prism and then passes through the receiving lens to the receiving detector to form the optical axis spot of the signal receiving self-calibration optical path.

[0024] The method for performing real-time on-orbit optical axis self-calibration of laser communication using the aforementioned cornerstone prism-based laser communication real-time optical axis self-calibration device includes the following steps:

[0025] Step 1: Calibrate the initial optical axis position of the signal transmission optical path. The signal transmitting laser emits a laser, and one of the six light spots is displayed on the receiving detector. The marked position is A1 (X1, Y1).

[0026] Step 2: Mark the initial optical axis position of the receiving optical path. The optical antenna receives the external signal and displays a light spot on the receiving detector. Mark the position A2 (X2, Y2).

[0027] Step 3: Mark the initial optical axis position of the signal receiving optical path. The self-calibration light source of the signal receiving detector emits a laser, which displays one of the six light spots on the receiving detector. The marked position is A3 (X3, Y3).

[0028] Step 4: During the communication process, after the external laser beam is reduced by the optical antenna, it is reflected by the second fast mirror, passed through the beam splitter, and collimated by the receiving lens. The received signal spot is displayed in real time on the window of the receiving detector. If there is a deviation, the spot is adjusted to position A2 by the second fast mirror.

[0029] Step 5: The signal transmitting laser in the signal transmitting optical path emits laser light, which is collimated by the transmitting lens, then reflected by a fast reflector, transmitted through a second beam splitter, reflected by the beam splitter, reflected back onto the beam splitter by a special corner cube prism, transmitted through the beam splitter, collimated by the receiving lens, and forms a light spot on the window of the receiving detector. Adjusting the angle of the fast reflector to position the light spot at point A1 completes the self-calibration of the signal transmitting branch. Because the special corner cube prism makes the A1 coordinate position far away from the A2 coordinate position, the receiving light spot and the signal transmitting self-calibration light spot can be displayed simultaneously without affecting normal transmission and reception communication.

[0030] Step 6: The self-calibration light source emits a laser, which is transmitted through the off-axis core fiber to the focal plane of the signal receiving lens. After being collimated by the signal receiving lens, the laser is reflected by the second beam splitter, then by the special corner cube prism, and finally through the beam splitter and collimated by the receiving lens, forming a signal receiving self-calibration spot on the receiving detector window. The angle of the second beam splitter is adjusted to position A2, completing the self-calibration of the signal receiving optical path. Because the special corner cube prism makes the A3 coordinate position far away from the A2 coordinate position, and because the signal receiving self-calibration is emitted from the off-axis core, the A3 coordinate position far away from the A1 coordinate position, and the spot distance is d2, the communication spot and the transmitting and receiving self-calibration spot can be displayed simultaneously without affecting normal transmission and reception communication.

[0031] Furthermore, the fast-reflecting mirror and the second fast-reflecting mirror are piezoelectric control systems or two-dimensional galvanometer control systems, used to achieve real-time correction when the optical path and optical axis deviate.

[0032] Furthermore, the right side of the beam splitter is provided with multiple optical paths, each containing a dual-core fiber. Each optical path selects a different dual-core fiber pitch, so multiple separate light spots can be displayed simultaneously on the receiving detector. Each light spot represents the real-time optical axis position of the corresponding optical path, realizing real-time monitoring of the optical axis position. Combined with the fast reflector of each optical path, real-time correction can be achieved when the optical axis of the displayed optical path deviates after self-calibration.

[0033] Furthermore, one or more optical paths are added to the right side of the beam splitter, each optical path containing a self-calibration light source for self-calibration of that optical path. Each added optical path and the self-calibration light source of the other optical paths emit in a time-division manner, so that the light spots of each branch formed on the receiving detector window can also be displayed and corrected in a time-division manner.

[0034] Furthermore, the optical antenna employs an off-axis reflective, coaxial reflective, or transmissive beam expander system.

[0035] Furthermore, the signal emitting laser is either a fiber-coupled laser or a spatial light output laser. When the signal emitting laser is a fiber-coupled laser, the signal emitting lens is a collimating lens; if the signal emitting laser is a spatial light output laser, the signal emitting lens is a beam expander group.

[0036] Furthermore, the receiving detector is a CCD detector or a four-quadrant photodetector.

[0037] Beneficial effects:

[0038] 1. This invention utilizes a special pyramidal prism to separate the self-calibration light spot for signal reception and transmission from the beacon receiving light spot, enabling the communication process and the self-calibration process to be performed simultaneously, thus achieving online calibration.

[0039] 2. This invention utilizes a dual-core receiving optical fiber to separate the self-calibration light spots for signal reception and signal transmission again, thereby enabling simultaneous calibration of the optical axes of multiple branches.

[0040] 3. The present invention has a simple structure and is easy to operate. It does not add any extra branches or devices and can achieve online self-calibration of the optical axes of each branch without increasing the complexity of the system. Attached Figure Description

[0041] Figure 1 This is a system block diagram of the present invention;

[0042] Figure 2 A schematic diagram of the outgoing light from a special angle cone prism when parallel light is incident on it;

[0043] Figure 3 This is a schematic diagram showing the distribution of the emitted light spot and the position of the optical axis when parallel light is incident on a special corner cube prism (with three equal dihedral angles);

[0044] Figure 4 This is a block diagram of the laser communication self-calibration device described in Example 3;

[0045] Figure 5 It is a component of the signal receiving detector described in Embodiment 3;

[0046] The following are the labels in the attached diagram: 1. Special corner cube prism; 2. Beam splitter; 3. Receiving lens; 4. Receiving detector; 5. Transmitting lens; 6. Transmitting laser; 7. Optical antenna; 8. Second beam splitter; 9. Fast-reflecting mirror; 10. Signal receiving lens; 11. Signal receiving detector; 11-1, Dual-core fiber; 11-2, On-axis core fiber; 11-3, Off-axis core fiber; 11-4, Optoelectronic processing equipment; 11-5, Self-calibrating light source; 12, Second fast-reflecting mirror. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0048] Example 1:

[0049] A laser communication on-orbit real-time optical axis self-calibration device based on a cornerstone prism is attached. Figure 1 As shown, it includes the following optical elements: a special corner cube prism 1, a beam splitter 2, a receiving lens 3, a receiving detector 4, a signal transmitting lens 5, and a signal transmitting laser 6. In this embodiment, the special corner cube prism 1 is as follows: Figure 2 As shown, the three dihedral angles of the special corner pyramid prism 1 are represented by θ. 12 θ 13 θ 23 Its angle is intentionally designed to be not equal to 90°, and its angle range satisfies the following formula: 0.03° < |θ 12 -90°| < 5°, 0.03° < |θ 13 -90°| < 5°, 0.03° < |θ 23 -90°|<5°. This causes a parallel beam of light to be reflected after incident, forming six parallel outgoing beams. Each outgoing beam has a certain angle with the incident beam (hereinafter referred to as the "beam deflection angle"). The greater the deviation of the dihedral angle of the special corner cube prism from 90°, the larger the beam deflection angle. Assuming the focal length of the tracking lens 3 is f2 and the beam deflection angle of the special corner cube prism is α, then the distance d1 between the six light spots and the center point is d1 = f2 * tan(α). The outgoing beams are separated into six light spots after passing through the receiving lens 3 and reaching the receiving detector 4. The centroid position of one of the six light spots can be calculated as the optical axis position of the optical path. The three dihedral angles of the special corner cube prism 1 being equal is a special case. In this case, the six light spots separated on the receiving detector 4 form a regular hexagon. The optical axis position of the optical path is represented by the calculated center position of the hexagon. Figure 3 As shown in Table 1, the relationship between the dihedral angle and beam deflection angle of the special corner pyramid prism (assuming the material of the special corner pyramid prism is K9) is obtained using optical simulation software.

[0050] Table 1. Relationship between the dihedral angle and beam deflection angle of a special corner cube prism:

[0051] Dihedral angle (°) of a special angled pyramid prism Beam deflection angle (°) 89.9 0.49637 89.85 0.74490 89.8 0.99365 89.75 1.24264 89.7 1.49183 89.65 1.74126 89.6 1.99095 89.55 2.24087 89.5 2.49103

[0052] The above-mentioned optical components are used to form a signal transmission optical path one, a receiving optical path one, and a signal transmission self-calibration optical path one;

[0053] The first signal transmission optical path is as follows: the signal transmitting laser 6 emits a laser, which passes through the signal transmitting lens 5 and reaches the rear surface of the beam splitter 2, and then transmits a signal outward through the beam splitter 2;

[0054] The receiving optical path one: the external signal is reflected by the front surface of the beam splitter 2, passes through the receiving lens 3 and reaches the receiving detector 4 to form a receiving spot;

[0055] The signal emission self-calibration optical path one: the signal emission laser 6 emits a laser beam, which passes through the signal emission lens 5 to the rear surface of the beam splitter 2, and is reflected by the rear surface of the beam splitter 2 to the special corner cube prism 1. The beam is reflected back to the beam splitter 2 by the special corner cube prism 1 and passes through the receiving lens 3 to the receiving detector 4 to form the emission optical axis self-calibration spot.

[0056] In the laboratory, the centroid positions of the light spot formed by the receiving optical path 1 and the signal emission light spot formed by the calibration optical path 1 are accurately calibrated. The centroid position of the light spot formed by the receiving optical path 1 represents the optical axis position of the receiving optical path 1, and the centroid position of the light spot formed by the calibration optical path 1 represents the optical axis position of the signal emission optical path 1. During communication, the centroid positions of the two light spots are acquired in real time. If this centroid differs from the centroid calibrated in the laboratory, it indicates a change in the corresponding optical axis, thus achieving self-calibration of the optical axis during communication. Because the special corner cube prism 1 keeps the light spot of the signal emission light emitted by the calibration optical path 1 away from the light spot of the receiving optical path, it does not affect the receiving communication. Because the beam splitter 2 diverts a small portion of the emitted light energy from the light spot of the signal emission light emitted by the calibration optical path 1, it is necessary to appropriately increase the optical power of the signal emission laser, but this does not affect the transmission communication.

[0057] The method for real-time on-orbit optical axis self-calibration of laser communication using the aforementioned cornerstone prism-based laser communication real-time optical axis self-calibration device includes the following steps:

[0058] Step 1: In a laboratory environment, calibrate the initial optical axis position of the signal transmission optical path one, the signal transmission laser 6 emits laser, and select one of the six light spots on the receiving detector 4, marking the position as A1 (X1, Y1).

[0059] Step 2: In a laboratory environment, mark the initial optical axis position of the receiving optical path one, receive external signals, and display a light spot on the receiving detector 4. Mark the position A2 (X2, Y2). Due to the special corner cube prism 1, the coordinates of A2 are far away from the coordinates of A1.

[0060] Step 3: During system communication, the signal emitting laser 6 emits signal light, which is collimated by the signal emitting lens 5 and then reflected by the rear surface of the beam splitter 2 and the special corner prism 1. The emitted signal light is reflected back to the beam splitter 2, passes through the beam splitter 2 and the receiving lens 3, and is displayed as spot A1' (X1', Y1') on the window of the receiving detector 4. The coordinate deviation between A1' and A1 is recorded as the real-time optical axis change of the first emission optical path.

[0061] Step 4: During system communication, the external laser is reflected sequentially by beam splitter 2, collimated by receiving lens 3, and then the received signal spot A2' (X2', Y2') is displayed in real time on the window of receiving detector 4. The coordinate deviation between A2' and A2 is recorded as the real-time optical axis change of receiving optical path one. Due to the special corner cube prism 1, the coordinates of A2' are far away from the coordinate position of A1'; therefore, the communication spot and the self-calibration spot can be displayed simultaneously without affecting normal transmission and reception.

[0062] Example 2:

[0063] The difference between this embodiment and Embodiment 1 is that a fast reflector can be added in front of the transmitting lens and the receiving lens. The fast reflector is a piezoelectric control system or a two-dimensional galvanometer control system, which can achieve real-time correction when the optical path and optical axis deviate.

[0064] Example 3:

[0065] The difference between this embodiment and Embodiment 1 is that, as Figure 4 As shown, the optical components also include an optical antenna 7, a second beam splitter 8, a fast-reflecting mirror 9, a signal receiving lens 10, a signal receiving detector 11, and a second fast-reflecting mirror 12. The signal receiving detector 11 is as follows... Figure 5 As shown, the system includes a dual-core fiber 11-1, an on-axis core fiber 11-2 which is the signal receiving fiber and connects to the optoelectronic processing device 11-4, and an off-axis core fiber 11-3 which is the signal receiving self-calibration fiber and connects to a self-calibration light source 11-5. Assuming the core pitch of the dual-core fiber is d1, the focal length of the signal receiving lens is f1, and the focal length of the receiving lens is f2, the distance d2 between the light spot on the detector after the light emitted by the signal receiving self-calibration light source returns through the pyramid and the optical axis spot of the signal receiving optical path is given by the formula d2 = f2 * d1 / f1.

[0066] The optical elements in this embodiment constitute a signal transmitting optical path two, a receiving optical path two, a signal receiving optical path, a signal transmitting self-calibration optical path two, and a signal receiving self-calibration optical path;

[0067] The second signal transmission optical path is as follows: the signal transmitting laser 6 emits a laser, which passes through the signal transmitting lens 5 to the front surface of the fast reflector 9, is reflected by the front surface of the fast reflector 9 to the second beam splitter 8, passes through the second beam splitter 8 to the rear surface of the beam splitter 2, and is reflected by the beam splitter 2 and the second fast reflector 12, and then transmits the signal outward through the optical antenna 7.

[0068] The second receiving optical path: the external signal passes through the optical antenna 7, is reflected by the second fast mirror 12, reaches the front surface of the beam splitter 2, is reflected by the front surface of the beam splitter 2, passes through the receiving lens 3, and reaches the receiving detector 4 to form a receiving spot.

[0069] The signal receiving optical path is as follows: the external signal passes through the optical antenna 7 and is reflected by the second fast mirror 12, then reaches the front surface of the beam splitter 2, passes through the beam splitter 2 and reaches the front surface of the second beam splitter 8, is reflected by the front surface of the second beam splitter 8, passes through the signal receiving lens 10 and reaches the signal receiving detector 11, and is transmitted to the optoelectronic processing device 11-4 through the on-axis core optical fiber 11-2.

[0070] The signal emission self-calibration optical path two: the signal emission laser 6 emits a laser beam, which passes through the signal emission lens 5 to the front surface of the fast reflector 9, is reflected by the front surface of the fast reflector 9 to the second beam splitter 8, passes through the second beam splitter 8 to the rear surface of the beam splitter 2, is reflected by the rear surface of the beam splitter 2 to the special corner cube prism 1, and the beam is reflected back to the beam splitter 2 by the special corner cube prism 1 and passes through the receiving lens 3 to the receiving detector 4 to form the optical axis spot of the signal emission self-calibration optical path;

[0071] The signal receiving self-calibration optical path is as follows: the self-calibration light source 11-5 emits a laser beam, which passes through the signal receiving lens 10 to the front surface of the second beam splitter 8, is reflected by the front surface of the second beam splitter 8 to the rear surface of the beam splitter 2, is reflected by the rear surface of the beam splitter 2 to the special corner cube prism 1, and the beam is reflected back to the beam splitter 2 by the special corner cube prism 1 and passes through the receiving lens 3 to the receiving detector 4 to form the optical axis spot of the signal receiving self-calibration optical path.

[0072] Similarly, multiple optical paths can be added to the right side of the beam splitter 2, each containing a dual-core fiber. Each optical path can select a different dual-core fiber pitch, so multiple separate light spots can be displayed simultaneously on the receiving detector 4. Each light spot represents the real-time optical axis position of the corresponding optical path, realizing real-time monitoring of the optical axis position. Combined with the fast reflector of each optical path, real-time correction can be achieved when the optical axis of the displayed optical path deviates after self-calibration.

[0073] The method for real-time on-orbit optical axis self-calibration of laser communication using the aforementioned cornerstone prism-based laser communication real-time optical axis self-calibration device includes the following steps:

[0074] Step 1: Calibrate the initial optical axis position of the signal transmitting optical path 2. The signal transmitting laser 6 emits a laser, and one of the six light spots is displayed on the receiving detector 4. The marked position is A1 (X1, Y1).

[0075] Step 2: Mark the initial optical axis position of the receiving optical path 2. The optical antenna 7 receives the external signal and displays a light spot on the receiving detector 4. Mark the position A2 (X2, Y2).

[0076] Step 3: Mark the initial optical axis position of the signal receiving optical path. The self-calibration light source 11-5 of the signal receiving detector 11 emits a laser, which displays one of the six light spots on the receiving detector 4. The marked position is A3 (X3, Y3).

[0077] Step 4: During the communication process, after the external laser beam is narrowed by the optical antenna 7, it is reflected by the second fast reflector 12, reflected by the beam splitter 2, and collimated by the receiving lens 3 and the tracking lens. The received signal spot is displayed in real time on the window of the receiving detector 4. If there is a deviation, the spot is adjusted to position A2 by the second fast reflector 12.

[0078] Step 5: The laser emitted by the signal transmitting laser in the second signal transmitting optical path emits a laser beam. After being collimated by the transmitting lens 5, the beam is reflected sequentially by the fast reflector 9, passes through the second beam splitter 8, is reflected by the beam splitter 2, is reflected back onto the beam splitter 2 by the special corner bevel prism 1, passes through the beam splitter 2, is collimated by the receiving lens 3, and forms a light spot on the window of the receiving detector 4. Adjusting the angle of the fast reflector 9 to adjust the position of the light spot to point A1 completes the self-calibration of the second signal transmitting branch. Because the special corner bevel prism 1 makes the A1 coordinate position far away from the A2 coordinate position, the receiving light spot and the signal transmitting self-calibration light spot can be displayed simultaneously without affecting normal transmission and reception communication.

[0079] Step 6: The self-calibration light source 11-5 emits a laser, which is transmitted through the off-axis core fiber 11-3 to the focal plane of the signal receiving lens 10. After being collimated by 10, the laser is reflected by the second beam splitter 8, the beam splitter 2, the special corner cube prism 1, and then through the beam splitter 2. After being collimated by the receiving lens 3, a signal receiving self-calibration spot is formed on the window of the receiving detector 4. The angle of the second beam splitter 8 is adjusted to adjust the position of the spot to position A2. The self-calibration of the signal receiving optical path is completed. Because the special corner cube prism 1 makes the A3 coordinate position far away from the A2 coordinate position, and because the signal receiving self-calibration is emitted from the off-axis core, the A3 coordinate position far away from the A1 coordinate position, and the spot distance is d2, the communication spot and the transmitting and receiving self-calibration spot can be displayed simultaneously without affecting normal transmission and reception communication.

[0080] Example 4:

[0081] The difference between this embodiment and embodiment 1 is that one or more optical paths can be added to the right side of the beam splitter 2 in the device. Each optical path contains a self-calibration light source for self-calibration of the optical path. Each added optical path and the self-calibration light source of the other optical paths emit in a time-division manner, so that the light spots of each branch formed on the receiving detector window can also be displayed and corrected in a time-division manner.

[0082] An optical antenna can be added to the left side of the beam splitter 2 of this invention, employing an off-axis, coaxial, or transmissive beam expander system to achieve large-aperture, long-distance communication. If a transmissive beam expander system is used, the optical antenna must eliminate the chromatic aberration between the laser emission wavelength and the reception wavelength.

[0083] The signal emitting laser 6 of this invention is either an optical fiber coupled laser or a spatial light output laser. If the signal emitting laser 6 is an optical fiber coupled laser, then the signal emitting lens 5 is a collimating lens; if the signal emitting laser 6 is a spatial light output laser, then the signal emitting lens 5 is a beam expander group. The receiving detector 4 is a CCD detector or a four-quadrant photodetector.

Claims

1. A laser communication on-orbit real-time optical axis self-calibration device based on a cornerstone prism, comprising the following optical components: a special cornerstone prism (1), a beam splitter (2), a receiving lens (3), a receiving detector (4), a signal transmitting lens (5), and a signal transmitting laser (6); characterized in that, The three dihedral angles of the special corner cube prism (1) are represented as θ 12 , θ 13 , θ 23 , the angle design is not equal to 90°, and the angle range satisfies the following formula: 0.03°<|θ 12 -90°|<5°, 0.03°<|θ 13 -90°|<5°, 0.03°<|θ 23 -90°|<5°, so that a parallel light beam is reflected to form 6 parallel outgoing light beams, the included angle between each outgoing light beam and the incident light beam is called the beam deflection angle, the greater the deviation of the dihedral angle of the special corner cube prism from 90°, the greater the beam deflection angle; The optical components also include an optical antenna (7), a second beam splitter (8), a fast reflector (9), a signal receiving lens (10), a signal receiving detector (11), and a second fast reflector (12). The signal receiving detector (11) includes a dual-core fiber (11-1), an on-axis core fiber (11-2) which is a signal receiving fiber connected to an optoelectronic processing device (11-4), and an off-axis core fiber (11-3) which is a signal receiving self-calibration fiber connected to a self-calibration light source (11-5). Assuming the core spacing of the dual-core fiber is d1, the focal length of the signal receiving lens is f1, and the focal length of the receiving lens is f2, the distance d2 between the light spot on the detector after the light emitted by the signal receiving self-calibration light source returns through the pyramid and the optical axis spot of the signal receiving optical path is given by the formula d2=f2*d1 / f1. The optical elements constitute a signal transmitting optical path two, a receiving optical path two, a signal receiving optical path, a signal transmitting self-calibration optical path two, and a signal receiving self-calibration optical path; The second signal transmission optical path is as follows: the signal transmitting laser (6) emits laser light, which passes through the signal transmitting lens (5) to the front surface of the fast reflector (9), is reflected by the front surface of the fast reflector (9) to the second beam splitter (8), passes through the second beam splitter (8) to the rear surface of the beam splitter (2), and is reflected by the beam splitter (2) and the second fast reflector (12) before being transmitted outward through the optical antenna (7); The second receiving optical path: the external signal passes through the optical antenna (7), is reflected by the second fast mirror (12), and reaches the front surface of the beam splitter (2). After being reflected by the front surface of the beam splitter (2), it passes through the receiving lens (3) and reaches the receiving detector (4) to form a receiving spot. The signal receiving optical path is as follows: the external signal passes through the optical antenna (7), is reflected by the second fast mirror (12), reaches the front surface of the beam splitter (2), passes through the beam splitter (2) to the front surface of the second beam splitter (8), is reflected by the front surface of the second beam splitter (8), passes through the signal receiving lens (10) to the signal receiving detector (11), and is transmitted to the optoelectronic processing device (11-4) through the on-axis core optical fiber (11-2). The signal emission self-calibration optical path two: The signal emission laser (6) emits laser light, which passes through the signal emission lens (5) to the front surface of the fast reflector (9), is reflected by the front surface of the fast reflector (9) to the second beam splitter (8), passes through the second beam splitter (8) to the rear surface of the beam splitter (2), is reflected by the rear surface of the beam splitter (2) to the special corner cube prism (1), and is reflected back to the beam splitter (2) by the special corner cube prism (1) and passes through the receiving lens (3) to the receiving detector (4) to form the optical axis spot of the signal emission self-calibration optical path; The signal receiving self-calibration optical path: the self-calibration light source (11-5) emits laser light, which passes through the signal receiving lens (10) to the front surface of the second beam splitter (8), is reflected by the front surface of the second beam splitter (8) to the rear surface of the beam splitter (2), is reflected by the rear surface of the beam splitter (2) to the special corner cube prism (1), and the beam is reflected back to the beam splitter (2) by the special corner cube prism (1) and passes through the receiving lens (3) to the receiving detector (4) to form the optical axis spot of the signal receiving self-calibration optical path.

2. The on-orbit real-time optical axis self-calibration device for laser communication based on a cornerstone prism according to claim 1, characterized in that, The fast reflector (9) and the second fast reflector (12) are piezoelectric control systems or two-dimensional galvanometer control systems, used to achieve real-time correction when the optical path and optical axis deviate.

3. The on-orbit real-time optical axis self-calibration device for laser communication based on a cornerstone prism according to claim 1 or 2, characterized in that, The beam splitter (2) has multiple optical paths on its right side, each containing a dual-core fiber. Each optical path selects a different dual-core fiber pitch, so multiple separate light spots can be displayed simultaneously on the receiving detector (4). Each light spot represents the real-time optical axis position of the corresponding optical path, realizing real-time monitoring of the optical axis position. Combined with the fast reflector of each optical path, it can realize real-time correction when the optical axis of the optical path deviates after self-calibration.

4. The on-orbit real-time optical axis self-calibration device for laser communication based on a cornerstone prism according to claim 1 or 2, characterized in that, One or more optical paths are added to the right side of the beam splitter (2). Each optical path contains a self-calibration light source for self-calibration of the optical path. Each added optical path and the self-calibration light source of the other optical paths are emitted in a time-division manner. Then, the light spots of each branch formed on the receiving detector window can also be displayed and corrected in a time-division manner.

5. The on-orbit real-time optical axis self-calibration device for laser communication based on a cornerstone prism according to claim 1, characterized in that, The optical antenna (7) adopts an off-axis reflective, coaxial reflective, or transmissive beam expander system.

6. The on-orbit real-time optical axis self-calibration device for laser communication based on a cornerstone prism according to claim 1 or 2, characterized in that, The signal emitting laser (6) is a fiber-coupled laser or a spatial light output laser. When the signal emitting laser (6) is a laser with fiber-coupled output, the signal emitting lens (5) is a collimating lens; if the signal emitting laser (6) is a laser with spatial light output, the signal emitting lens (5) is a beam expander group.

7. The on-orbit real-time optical axis self-calibration device for laser communication based on a cornerstone prism according to claim 1 or 2, characterized in that, The receiving detector (4) is a CCD detector or a four-quadrant photodetector.

8. A method for performing real-time on-orbit optical axis self-calibration of laser communication using the cornerstone prism-based laser communication real-time optical axis self-calibration device as described in claim 1, characterized in that, The method includes the following steps: Step 1: Mark the initial optical axis position of the signal transmitting optical path 2. The signal transmitting laser (6) emits laser light and displays one of the six light spots on the receiving detector (4). The marked position is A1 (X1, Y1). Step 2: Mark the initial optical axis position of the receiving optical path 2. The optical antenna (7) receives the external signal and displays a light spot on the receiving detector (4). Mark the position A2 (X2, Y2). Step 3: Mark the initial optical axis position of the signal receiving optical path. The self-calibration light source (11-5) of the signal receiving detector (11) emits laser light, and displays one of the six light spots on the receiving detector (4). The marked position is A3 (X3, Y3). Step 4: During the communication process, after the external laser beam is reduced by the optical antenna (7), it is reflected by the second fast reflector (12), passed through the beam splitter (2), and collimated by the receiving lens (3). The received signal spot is displayed in real time on the window of the receiving detector (4). If there is a deviation, the spot is adjusted to position A2 by the second fast reflector (12). Step 5: The laser emitted by the signal transmitting laser in the second signal transmitting optical path emits a laser beam. After being collimated by the transmitting lens (5), the laser beam is reflected by the fast reflector (9), transmitted through the second beam splitter (8), reflected by the beam splitter (2), reflected back onto the beam splitter (2) by the special corner bevel prism (1), transmitted through the beam splitter (2), collimated by the receiving lens (3), and formed on the window of the receiving detector (4). The position of the light spot is adjusted to point A1 by adjusting the angle of the fast reflector (9) to complete the self-calibration of the second signal transmitting branch. Since the special corner bevel prism (1) makes the A1 coordinate position far away from the A2 coordinate position, the receiving light spot and the signal transmitting self-calibration light spot can be displayed at the same time without affecting normal transmission and reception communication. Step 6: The self-calibration light source (11-5) emits laser light, which is transmitted to the focal plane of the signal receiving lens (10) through the off-axis core fiber (11-3). After being collimated by the signal receiving lens (10), the light is reflected by the second beam splitter (8), the beam splitter (2), the special corner bevel prism (1), and then through the beam splitter (2). After being collimated by the receiving lens (3), a signal receiving self-calibration spot is formed on the window of the receiving detector (4). The angle of the second beam splitter (8) is adjusted to adjust the position of the spot to position A2, thus completing the self-calibration of the signal receiving optical path. Because the special corner bevel prism makes the A3 coordinate far away from the A2 coordinate position, and because the signal receiving self-calibration is emitted by the off-axis core, the A3 coordinate far away from the A1 coordinate, and the spot distance is d2, the communication spot and the transmitting and receiving self-calibration spot can be displayed simultaneously without affecting normal transmission and reception communication.

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