Cube-corner prism-based laser communication in-orbit real-time optical axis self-calibration device and method

Abstract

The invention discloses a laser communication in-orbit real-time optical axis self-calibration device and method based on a cube-corner prism, and belongs to the technical field of optical communication equipment, the laser communication in-orbit real-time optical axis self-calibration device comprises the following optical elements: a special cube-corner prism, a spectroscope, a receiving lens, a receiving detector, a signal transmitting lens and a signal transmitting laser; three dihedral angles of the special cube-corner prism are represented as theta12, theta13 and theta23 and are designed to be not equal to 90 degrees, so that a parallel light beam is reflected to form six parallel emergent light beams after incidence, an included angle formed by each emergent light beam and the incident light beam is called a light beam deflection angle, and the larger the deviation between the dihedral angle of the special cube-corner prism and 90 degrees is, the larger the light beam deflection angle is; the optical elements form a signal transmitting optical path, a receiving optical path and a signal transmitting self-calibration optical path. On the basis of not adding extra self-calibration branches and devices, in-orbit real-time optical axis self-calibration of the satellite-borne laser communication terminal can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical communication equipment, and in particular relates to an on-orbit real-time optical axis self-calibration device and method for laser communication based on corner cube prisms. Background Art

[0002] In the field of satellite-borne laser communications, the optical axes of the communication terminal's signal transmission, signal reception, and tracking reception paths must remain parallel. As communication distances continue to 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 satellite-borne laser communication terminals are subject to vibration and impact during transportation, launch, and on-orbit operation, the parallelism of the optical axes is severely affected. Therefore, on-orbit calibration of the parallelism of each optical path is crucial.

[0003] Chinese patent application number CN201811554230 proposes an on-orbit calibration and transceiver coaxiality correction device and method for satellite optical communication terminals. The device calibrates the signal transmission optical path, signal reception optical path, and beacon reception optical path using a conventional angle cone and an external calibration transmission branch, a signal internal calibration transmission branch, a beacon internal calibration transmission branch, and a calibration reflector. Limitations of this patent lie in the addition of multiple branches for calibration and compensation, resulting in a complex method. Furthermore, calibration and communication require time-sharing and cannot be performed simultaneously. Chinese patent application number CN201810945384 proposes an optical axis self-calibration device and method for an optical communication system. This device uses a conventional angle cone and dual-core optical fiber (for both transmission and self-calibration) to calibrate the transmission optical path. No additional branches are added, but this also requires communication interruption, preventing real-time self-calibration of the optical axis during communication. The limitation of using conventional angle cones is that the outgoing light beam is parallel to the incident light beam. Therefore, when the optical axes of each branch are coaxial, the self-calibration light spot and the beacon receiving light spot coincide or are very close, resulting in indistinguishability and difficulty in processing. Beacon reception and self-calibration need to be processed in time-sharing, and real-time calibration on orbit cannot be achieved (self-calibration of the optical axis during normal communication process).

[0004] In summary, the currently disclosed laser communication self-calibration methods have limitations and none of them have the ability to calibrate in real time on orbit. Therefore, it is an important issue that technical personnel in this field need to urgently solve to develop a laser communication self-calibration device and method with real-time on-orbit calibration capability and a simple structure. Summary of the Invention

[0005] In response to the above-mentioned problems, the present invention proposes an on-orbit real-time optical axis self-calibration device and method for laser communication based on corner cube prisms. Without adding additional self-calibration branches and devices, the on-orbit real-time optical axis self-calibration of the satellite-borne laser communication terminal can be realized, and the optical axis calibration of the transmitting and receiving light circuits can be performed in real time without interrupting communication.

[0006] The above purpose is achieved through the following technical solutions:

[0007] A laser communication on-orbit real-time optical axis self-calibration device based on a corner cube prism includes the following optical elements: a special corner cube 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 corner cube prism are represented by θ 12 ,θ 13 ,θ 23 , its angle is deliberately 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°. A parallel beam of light is incident and then reflected to form 6 parallel outgoing beams. The angle formed by each outgoing beam and the incident beam is called the beam deflection angle. The greater the deviation of the dihedral angle of the special corner cube from 90°, the greater the beam deflection angle.

[0008] The above optical components constitute the signal transmission optical path 1, the receiving optical path 1 and the signal transmission self-calibration optical path 1;

[0009] The signal transmission optical path 1 includes a signal transmission laser, a signal transmission lens, and a spectroscope; the signal transmission laser emits laser light, which passes through the signal transmission lens and reaches the rear surface of the spectroscope, and then transmits the signal outward through the spectroscope;

[0010] The receiving optical path 1 includes a spectroscope, a receiving lens, and a receiving detector; the external signal is reflected by the front surface of the spectroscope, passes through the receiving lens, and reaches the receiving detector to form a receiving light spot;

[0011] The signal transmission self-calibration optical path includes a signal transmission laser, a signal transmission lens, a receiving lens, a receiving detector, a beam splitter, and a special corner cube prism; the signal transmission laser emits laser light, which passes through the signal transmission lens and reaches the rear surface of the beam splitter, and is reflected from the rear surface of the beam splitter to the special corner cube prism. The light beam is reflected back to the beam splitter through the special corner cube prism and passes through the receiving lens in turn to reach the receiving detector to form a self-calibration light spot of the transmission optical axis.

[0012] The present invention also provides a method for performing on-orbit real-time optical axis self-calibration for laser communication using the above-mentioned on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms, 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 selects one of the six light spots on the receiving detector and marks the position as A1 (X1, Y1).

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

[0015] Step 3: During the system communication process, the signal transmitting laser emits signal light, which is collimated by the signal transmitting lens and then reflected by the rear surface of the beam splitter. The special corner cube prism 1 reflects the transmitted signal light back to the beam splitter. The light passes through the beam splitter and the receiving lens, and the light spot A1' (X1', Y1') is displayed 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 transmitting 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 coordinate of A2' is 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.

[0017] As a further improvement of the present invention, the optical element also includes an optical antenna, a second spectrometer, a quick reflex mirror, a signal receiving lens, a signal receiving detector, and a second quick reflex mirror, wherein the signal receiving detector includes a dual-core optical fiber, the on-axis core optical fiber is the signal receiving optical fiber, which is connected to the photoelectric processing equipment, and the off-axis core optical fiber is the signal receiving self-calibration optical fiber, which is connected to a self-calibration light source; assuming that the core distance 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, then the distance d2 between the light spot on the detector emitted by the signal receiving self-calibration light source after returning through the angle cone and the light spot on the optical axis of the signal receiving optical path is given by the formula d2=f2*d1 / f1;

[0018] The optical elements constitute the second signal transmission optical path, the second receiving optical path, the signal receiving optical path, the second signal transmission self-calibration optical path and the signal receiving self-calibration optical path;

[0019] The second signal transmission optical path: the signal transmission laser emits laser light, which passes through the signal transmission lens and reaches the front surface of the quick reflection mirror, is reflected by the front surface of the quick reflection mirror to the second beam splitter, passes through the second beam splitter and reaches the rear surface of the beam splitter, passes through the beam splitter and the second quick reflection mirror, and then transmits the signal 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 reflection 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 light spot;

[0021] The signal receiving optical path: the external signal passes through the optical antenna and is reflected by the second fast reflection mirror, reaches the front surface of the beam splitter, passes through the beam splitter and reaches 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 and reaches the signal receiving detector, and is transmitted to the photoelectric processing device through the on-axis core;

[0022] The signal emission self-calibration optical path 2: the signal emission laser emits laser light, which passes through the signal emission lens and reaches the front surface of the quick reflector, is reflected by the front surface of the quick reflector to the second beam splitter, passes through the second beam splitter to reach the rear surface of the beam splitter, is reflected by the rear surface of the beam splitter to the special corner cube prism, and the light beam is reflected back to the beam splitter through the special corner cube prism and sequentially passes through the receiving lens to reach the receiving detector to form the optical axis light spot of the signal emission self-calibration optical path;

[0023] The signal is received from the calibration optical path: the laser is emitted from the calibration light source, 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 the special corner cube prism, the light beam is reflected back to the beam splitter through the special corner cube prism and passes through the receiving lens in turn to reach the receiving detector to form the optical axis light spot of the signal received from the calibration optical path.

[0024] A method for performing on-orbit real-time optical axis self-calibration of laser communication using the above-mentioned on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms comprises the following steps:

[0025] Step 1: Calibrate the initial optical axis position of the signal transmission optical path. The signal transmission laser emits laser light, 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 a light spot is displayed on the receiving detector, marked as 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 laser light, and one of the six light spots is displayed on the receiving detector. The marked position is A3 (X3, Y3).

[0028] Step 4: During the communication process, the external laser beam is beam-contracted by the optical antenna, then reflected by the second quick-reflection 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 any deviation, the second quick-reflection mirror is used to adjust the spot to position A2.

[0029] Step 5: The signal transmitting laser of the signal transmitting optical path emits laser light, which is collimated by the transmitting lens and then reflected by the fast mirror, transmitted by the second beam splitter, reflected by the beam splitter, reflected back to the beam splitter by the special corner cube prism, transmitted by the beam splitter, collimated by the receiving lens, and forms a light spot on the window of the receiving detector. The angle of the fast mirror is adjusted to adjust the position of the light spot to point A1 to complete the self-calibration of the signal transmitting branch. Because the special corner cube prism makes the A1 coordinate 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 sending and receiving communications.

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

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

[0032] Furthermore, multiple optical paths are arranged on the right side of the spectroscope, all of which include dual-core optical fibers. A different dual-core optical fiber core distance is selected for each optical path, so that multiple separated 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 realized 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 spectrometer, and each optical path contains a self-calibration light source for self-calibration of the optical path. Each added optical path is emitted in a time-sharing manner with the self-calibration light sources of the remaining optical paths, so that the branch light spots formed on the receiving detector window can also be displayed and corrected in a time-sharing manner.

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

[0035] Furthermore, the signal transmitting laser is a fiber-coupled output laser or a spatial light output laser. When the signal transmitting laser is a fiber-coupled output laser, the signal transmitting lens is a collimator lens; if the signal transmitting laser is a spatial light output laser, the signal transmitting lens is a beam expander lens assembly.

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

[0037] Beneficial effects:

[0038] 1. The present invention utilizes a special corner cube prism to separate the self-calibration light spot for signal reception and transmission from the beacon reception light spot, so that the communication process and the self-calibration process can be carried out simultaneously, thus realizing online calibration.

[0039] 2. The present invention utilizes a dual-core receiving optical fiber to separate the self-calibration light spots for signal reception and signal transmission again, thereby achieving 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 require any additional branches or devices, and can achieve online self-calibration of the optical axes of each branch without increasing the complexity of the system. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0042] Figure 2 Schematic diagram of the output light when parallel light enters the special corner cube prism;

[0043] Figure 3 This is a schematic diagram of the output light spot distribution and the position of the optical axis of the light path when parallel light enters a special corner cube prism (the three dihedral angles are equal);

[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 Example 3;

[0046] Explanation of the reference numerals in the figure: 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. Quick reflex mirror; 10. Signal receiving lens; 11. Signal receiving detector; 11-1, dual-core optical fiber; 11-2, on-axis core optical fiber; 11-3, off-axis core optical fiber; 11-4, optoelectronic processing equipment; 11-5, self-calibration light source; 12. Second quick reflex mirror. DETAILED DESCRIPTION

[0047] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0048] Example 1:

[0049] A real-time optical axis self-calibration device for laser communication on-orbit based on corner cube prism is shown in the attached figure. 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. The special corner cube prism 1 in this embodiment is as shown in FIG. Figure 2 As shown, the three dihedral angles of the special corner cube prism 1 are represented by θ 12 ,θ 13 ,θ 23 , its angle is deliberately 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°. A beam of parallel light is incident and then reflected to form 6 beams of parallel outgoing light. Each outgoing light beam has a certain angle with the incident light beam (hereinafter referred to as the "beam deflection angle"). The greater the deviation of the dihedral angle of the special corner cone prism from 90°, the greater the beam deflection angle. Assuming that the focal length of the tracking lens 3 is f2 and the beam deflection angle of the special corner cone prism is α, the distance between the 6 light spots and the center point is d1=f2*tan(α). The outgoing light beam passes through the receiving lens 3 and reaches the receiving detector 4, where it is separated into 6 light spots. One of the six light spots can be selected to calculate the center of mass position as the optical axis position of the light path. The three dihedral angles of the special corner cone prism 1 are equal, which is a special case. The 6 light spots separated on the receiving detector 4 form a regular hexagon, which is expressed as the optical axis position of the light path by calculating the center position of the hexagon, such as Figure 3 The relationship between the dihedral angle of the special corner cube and the beam deflection angle obtained using optical simulation software is shown in Table 1 (the material of the special corner cube is assumed to be K9).

[0050] Table 1 Relationship between the dihedral angle of special corner cube prism and the beam deflection angle Special corner cube prism dihedral angle (°) 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

[0051] The above optical components are used to form a signal transmission optical path 1, a receiving optical path 1 and a signal transmission self-calibration optical path 1;

[0052] The signal transmission optical path 1: the signal transmission laser 6 emits laser light, which passes through the signal transmission lens 5 and reaches the rear surface of the beam splitter 2, and then transmits the signal outward through the beam splitter 2;

[0053] The receiving optical path 1: 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 light spot;

[0054] The signal emission self-calibration optical path 1: the signal emission laser 6 emits a laser, which passes through the signal emission lens 5 to reach 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 light beam is reflected back to the beam splitter 2 through the special corner cube prism 1 and passes through the receiving lens 3 in turn to reach the receiving detector 4 to form a self-calibration light spot of the emission optical axis.

[0055] The centroid position of the light spot of the receiving optical path one and the centroid position of the light spot formed by the signal emission from the calibration optical path one are accurately calibrated in the laboratory, wherein the centroid position of the light spot of the receiving optical path one is expressed as the optical axis position of the receiving optical path one, and the centroid position of the light spot of the signal emission from the calibration optical path one is expressed as the optical axis position of the signal emission optical path one. During the communication process, the centroid positions of the two light spots are collected in real time. If the centroid is different from the laboratory calibration centroid, it means that the corresponding optical axis has changed, thereby realizing the self-calibration of the optical axis during the communication process. Due to the special corner cube prism 1, the light spot of the signal emission from the calibration optical path one is far away from the light spot of the receiving optical path, which does not affect the receiving communication; due to the spectroscope 2, the light spot of the signal emission from the calibration optical path one divides a small part of the energy of the emitted light, it is necessary to moderately increase the optical power of the signal emission laser, which does not affect the transmitting communication.

[0056] The method for performing on-orbit real-time optical axis self-calibration of laser communication using the above-mentioned on-orbit real-time optical axis self-calibration device based on a corner cube prism comprises the following steps:

[0057] Step 1: In a laboratory environment, calibrate the initial optical axis position of the signal transmission optical path 1. The signal transmission laser 6 emits laser light, and selects one of the six light spots on the receiving detector 4, marking the position as A1 (X1, Y1).

[0058] Step 2: In a laboratory environment, mark the initial optical axis position of the receiving optical path 1, receive an external signal, and display a light spot on the receiving detector 4, marking the position A2 (X2, Y2). Due to the special corner cube prism 1, the A2 coordinate is far away from the A1 coordinate position.

[0059] Step 3: During system communication, the signal transmitting laser 6 emits signal light, which is collimated by the signal transmitting lens 5 and then reflected by the rear surface of the beam splitter 2. The special corner cube prism 1 reflects the transmitted signal light back to the beam splitter 2, passes through the beam splitter 2, and the receiving lens 3. The light spot A1' (X1', Y1') is displayed 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 transmitting optical path 1.

[0060] Step 4: During system communication, the external laser is reflected by beam splitter 2 and collimated by receiving lens 3. 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 1. Due to the special corner cube prism 1, the coordinates of A2' are moved 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.

[0061] Example 2:

[0062] The difference between this embodiment and embodiment 1 is that a fast reflection mirror can be added in front of the transmitting lens and the receiving lens. The fast reflection mirror is a piezoelectric control system or a two-dimensional galvanometer control system, which can achieve real-time correction when the optical axis of the optical path deviates.

[0063] Example 3:

[0064] The difference between this embodiment and embodiment 1 is that Figure 4 As shown, the optical elements further include an optical antenna 7, a second beam splitter 8, a quick-reflection mirror 9, a signal receiving lens 10, a signal receiving detector 11, and a second quick-reflection mirror 12. The signal receiving detector 11 is as shown in FIG. Figure 5 As shown, the system comprises a dual-core fiber 11-1. The on-axis core fiber 11-2 is the signal receiving fiber, connected to the optoelectronic processing device 11-4. The off-axis core fiber 11-3 is the signal receiving self-calibration fiber, connected to a self-calibration light source 11-5. Assuming the core distance 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 spot on the detector and the optical axis spot of the signal receiving optical path after the light emitted from the signal receiving self-calibration light source passes through the cone angle is given by the formula d2 = f2 * d1 / f1.

[0065] The optical elements in this embodiment constitute the second signal transmission optical path, the second receiving optical path, the signal receiving optical path, the second signal transmission self-calibration optical path, and the second signal receiving self-calibration optical path;

[0066] The second signal transmission optical path: the signal transmission laser 6 emits a laser, which passes through the signal transmission lens 5 and reaches the front surface of the quick reflection mirror 9. The laser is reflected by the front surface of the quick reflection mirror 9 to the second beam splitter 8, passes through the second beam splitter 8 to the rear surface of the beam splitter 2, passes through the beam splitter 2 and the second quick reflection mirror 12, and then transmits the signal outward through the optical antenna 7;

[0067] The receiving optical path 2: the external signal passes through the optical antenna 7, is reflected by the second fast reflection 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 light spot;

[0068] The signal receiving optical path: the external signal passes through the optical antenna 7 and is reflected by the second fast reflection mirror 12, 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 photoelectric processing device 11-4 through the on-axis core 11-2;

[0069] The signal is emitted from the calibration optical path 2: the signal emission laser 6 emits a laser, which passes through the signal emission lens 5 and reaches the front surface of the quick reflection mirror 9, is reflected by the front surface of the quick reflection mirror 9 to the second beam splitter 8, passes through the second beam splitter 8 to reach the rear surface of the beam splitter 2, is reflected by the rear surface of the beam splitter 2 to the special corner cube 1, and the light beam is reflected back to the beam splitter 2 through the special corner cube 1 and sequentially passes through the receiving lens 3 to reach the receiving detector 4 to form the optical axis light spot of the signal emission from the calibration optical path;

[0070] The signal is received from the calibration optical path: the laser is emitted from the calibration light source 11-5, 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 1, and the light beam is reflected back to the beam splitter 2 through the special corner cube 1 and sequentially passes through the receiving lens 3 to the receiving detector 4 to form the optical axis light spot of the signal received from the calibration optical path;

[0071] Similarly, multiple optical paths can be added to the right side of the spectrometer 2, all containing dual-core optical fibers. A different dual-core optical fiber core distance is selected for each optical path, and multiple separated 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 realized when the optical axis deviation of the optical path is displayed after self-calibration.

[0072] The method for performing on-orbit real-time optical axis self-calibration of laser communication using the above-mentioned on-orbit real-time optical axis self-calibration device based on a corner cube prism comprises the following steps:

[0073] Step 1: calibrate the initial optical axis position of the signal transmission optical path 2. The signal transmission laser 6 emits laser light, and one of the six light spots is displayed on the receiving detector 4. The marked position is A1 (X1, Y1).

[0074] 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, marking the position A2 (X2, Y2).

[0075] 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 one of the six light spots is displayed on the receiving detector 4. The marked position is A3 (X3, Y3).

[0076] Step 4: During the communication process, the external laser beam is beam-contracted by the optical antenna 7, reflected by the second quick-reflection mirror 12, reflected by the beam splitter 2, and collimated by the tracking lens of the receiving lens 3. The received signal spot is displayed in real time on the window of the receiving detector 4. If there is any deviation, the second quick-reflection mirror 12 adjusts the spot to position A2.

[0077] Step 5: The signal transmitting laser of the second signal transmitting optical path emits a laser. After being collimated by the transmitting lens 5, it is reflected by the quick reflector 9, passes through the second beam splitter 8, and then reflected by the beam splitter 2. The special corner cube prism 1 reflects the light back to the beam splitter 2, passes through the beam splitter 2, and is collimated by the receiving lens 3 to form a light spot on the window of the receiving detector 4. The angle of the quick reflector 9 is adjusted to adjust the position of the light spot to point A1 to complete the self-calibration of the signal transmitting branch 2. Because the special corner cube prism 1 makes the A1 coordinate 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 sending and receiving communications.

[0078] Step 6: The self-calibration light source 11-5 emits a laser, which is transmitted to the focal plane of the signal receiving lens 10 through the off-axis core optical fiber 11-3. After being collimated by 10, it is reflected by the second beam splitter 8, the beam splitter 2, the special angle cube prism 1, passes through the beam splitter 2, and is collimated by the receiving lens 3 to form a signal receiving self-calibration light spot on the window of the receiving detector 4. Adjust the angle of the second beam splitter 8 to adjust the position of the light spot to the A2 position. The self-calibration of the signal receiving optical path is completed; because the special angle cube prism 1 makes the A3 coordinate away from the A2 coordinate position, and because the signal receiving self-calibration is an off-axis core emission, the A3 coordinate is away from the A1 coordinate, and the light spot distance is d2, so the communication light spot and the emission and reception self-calibration light spots can be displayed at the same time without affecting the normal transmission and reception communications;

[0079] Example 4:

[0080] The difference between this embodiment and embodiment 1 is that one or more optical paths can be added to the right side of the spectrometer 2 in the device, and each optical path contains a self-calibration light source for self-calibration of the optical path. Each added optical path is emitted in a time-sharing manner with the self-calibration light sources of the remaining optical paths, so that the branch light spots formed on the receiving detector window can also be displayed and corrected in a time-sharing manner.

[0081] An optical antenna can be added to the left side of the beam splitter 2 of the present invention, using an off-axis reflective, on-axis reflective, or transmissive beam expansion system to achieve large-aperture, long-distance communication. If a transmissive beam expansion system is used, the optical antenna must eliminate the chromatic aberration between the laser emission wavelength and the received wavelength.

[0082] The signal transmitting laser 6 of the present invention is a laser with fiber-coupled output or a laser with spatial light output. If the signal transmitting laser 6 is a laser with fiber-coupled output, the signal transmitting lens 5 is a collimator lens. If the signal transmitting laser 6 is a laser with spatial light output, the signal transmitting lens 5 is a beam expander lens assembly. 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 corner cube prism, comprising 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); characterized in that: The three dihedral angles of the special corner cube prism (1) are expressed as θ 12 ,θ 13 ,θ 23 , its angle is 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°, so that a parallel light beam is incident and reflected to form 6 parallel outgoing light beams. The angle formed by 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 from 90°, the greater the beam deflection angle. The above optical components constitute the signal transmission optical path 1, the receiving optical path 1 and the signal transmission self-calibration optical path 1; The signal transmission optical path 1 includes a signal transmission laser (6), a signal transmission lens (5), and a spectroscope (2); the signal transmission laser (6) transmits laser light, which passes through the signal transmission lens (5) and reaches the rear surface of the spectroscope (2), and transmits the signal outward through the spectroscope (2); The receiving optical path 1 comprises a spectroscope (2), a receiving lens (3), and a receiving detector (4); the external signal is reflected by the front surface of the spectroscope (2), passes through the receiving lens (3), and reaches the receiving detector (4) to form a receiving light spot; The signal emission self-calibration optical path includes a signal emission laser (6), a signal emission lens (5), a receiving lens (3), a receiving detector (4), a spectroscope (2), and a special angle cone prism (1); the signal emission laser (6) emits laser light, which passes through the signal emission lens (5) and reaches the rear surface of the spectroscope (2), and is reflected from the rear surface of the spectroscope (2) to the special angle cone prism (1); the light beam passes through the special angle cone prism (1) and is reflected back to the spectroscope (2) and passes through the receiving lens (3) in turn and reaches the receiving detector (4) to form a self-calibration light spot of the emission optical axis.

2. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prism according to claim 1, characterized in that: The optical element further includes an optical antenna (7), a second spectroscope (8), a quick-reflection mirror (9), a signal receiving lens (10), a signal receiving detector (11), and a second quick-reflection mirror (12), wherein the signal receiving detector (11) includes a dual-core optical fiber (11-1), an on-axis core optical fiber (11-2) being a signal receiving optical fiber connected to a photoelectric processing device (11-4), and an off-axis core optical fiber (11-3) being a signal receiving self-calibration optical fiber connected to a self-calibration light source (11-5); assuming that the core distance 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, then the distance d2 between the light spot on the detector emitted by the signal receiving self-calibration light source after returning through the cone angle and the light spot on the optical axis of the signal receiving light path is given by the formula d2=f2*d1 / f1; The optical elements constitute the second signal transmission optical path, the second receiving optical path, the signal receiving optical path, the second signal transmission self-calibration optical path and the signal receiving self-calibration optical path; The second signal transmission optical path: the signal transmission laser (6) emits laser light, which passes through the signal transmission lens (5) and reaches the front surface of the quick reflection mirror (9), is reflected by the front surface of the quick reflection mirror (9) to the second beam splitter (8), passes through the second beam splitter (8) and reaches the rear surface of the beam splitter (2), is reflected by the beam splitter (2) and the second quick reflection mirror (12), and then transmits the signal 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-reflecting mirror (12), reaches the front surface of the spectroscope (2), is reflected by the front surface of the spectroscope (2), passes through the receiving lens (3), reaches the receiving detector (4), and forms a receiving light spot; The signal receiving optical path: the external signal passes through the optical antenna (7), is reflected by the second fast reflection mirror (12), reaches the front surface of the beam splitter (2), passes through the beam splitter (2), 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), reaches the signal receiving detector (11), and is transmitted to the photoelectric processing device (11-4) through the on-axis core (11-2); The signal is emitted from the calibration optical path 2: the signal emitting laser (6) emits laser light, passes through the signal emitting lens (5) to reach the front surface of the quick-reflecting mirror (9), is reflected by the front surface of the quick-reflecting mirror (9) to the second beam splitter (8), passes through the second beam splitter (8) to reach 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 light beam is reflected back to the beam splitter (2) through the special corner cube prism (1) and sequentially passes through the receiving lens (3) to reach the receiving detector (4) to form the optical axis spot of the signal emission from the calibration optical path; The signal is received from the calibration optical path: the calibration light source (11-5) emits a laser, passes through the signal receiving lens (10) to reach the front surface of the second beam splitter (8), passes through the front surface of the second beam splitter (8) and is reflected to the rear surface of the beam splitter (2), and is reflected to the special corner cone prism (1) through the rear surface of the beam splitter (2). The light beam is reflected back to the beam splitter (2) through the special corner cone prism (1) and passes through the receiving lens (3) in turn to reach the receiving detector (4) to form an optical axis light spot of the signal received from the calibration optical path.

3. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms according to claim 1, characterized in that: The fast-reflection mirror (9) and the second fast-reflection mirror (12) are piezoelectric control systems or two-dimensional galvanometer control systems, and are used to achieve real-time correction when the optical axis of the optical path deviates.

4. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prism according to claim 2 or 3, characterized in that: A plurality of optical paths are provided on the right side of the spectroscope (2), each of which includes a dual-core optical fiber. A different dual-core optical fiber core distance is selected for each optical path, so that a plurality of separated 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, thereby realizing real-time monitoring of the optical axis position. In combination with the fast reflector of each optical path, real-time correction can be realized when the optical axis of the optical path deviates after self-calibration.

5. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prism according to claim 1 or 2, characterized in that: One or more optical paths are added to the right side of the spectroscope (2), each optical path contains a self-calibration light source for self-calibration of the optical path, and each added optical path is time-shared with the self-calibration light sources of the remaining optical paths, so that the branch light spots formed on the receiving detector window can also be displayed and corrected in a time-shared manner.

6. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms according to claim 2, characterized in that: The optical antenna (7) adopts an off-axis reflection type, a coaxial reflection type or a transmission type beam expansion system.

7. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms according to claim 1 or 2, characterized in that: The signal emitting laser (6) is a laser with optical fiber coupling output or a laser with spatial light output; When the signal emitting laser (6) is a laser with optical fiber coupling 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 lens group.

8. The on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms according to claim 1 or 2, characterized in that: The receiving detector (4) is a CCD detector or a four-quadrant photoelectric detector.

9. A method for performing on-orbit real-time optical axis self-calibration for laser communication using the on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms according to claim 1, characterized in that: The method comprises the following steps: Step 1: In a laboratory environment, calibrate the initial optical axis position of the signal transmission optical path 1, the signal transmission laser (6) emits laser light, and selects one of the six light spots on the receiving detector (4), marking the position as A1 (X1, Y1); Step 2: In a laboratory environment, mark the initial optical axis position of the receiving optical path 1, receive an external signal, and display a light spot on the receiving detector (4), marking the position A2 (X2, Y2). Due to the special corner cube prism (1), the coordinate of A2 is far away from the coordinate position of A1; Step 3: During the system communication process, the signal transmitting laser (6) emits laser light, which is collimated by the signal transmitting lens (5) and then reflected by the rear surface of the beam splitter (2) and the special corner cube prism (1) to reflect the transmitted signal light back to the beam splitter (2). The light passes through the beam splitter (2) and the receiving lens (3), and is displayed 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 transmitting optical path 1; Step 4: During the system communication process, the external laser is reflected by the beam splitter (2) and collimated by the receiving lens (3), and the receiving signal spot A2' (X2', Y2') is displayed in real time on the window of the receiving detector (4). The coordinate deviation between A2' and A2 is recorded as the real-time optical axis change of the receiving optical path 1; due to the special corner cube prism (1), the coordinate of A2' is far away from the coordinate position of A1'; therefore, the communication spot and the self-calibration spot can be displayed at the same time without affecting the normal sending and receiving communication.

10. A method for performing on-orbit real-time optical axis self-calibration of laser communication using the on-orbit real-time optical axis self-calibration device for laser communication based on corner cube prisms according to claim 2, characterized in that: The method comprises the following steps: Step 1: calibrate the initial optical axis position of the signal transmission optical path 2, the signal transmission laser (6) emits laser light, and one of the six light spots is displayed on the receiving detector (4), and 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), marking the position A2 (X2, Y2). Step 3: Mark the initial optical axis position of the signal receiving optical path, and the self-calibration light source (11-5) of the signal receiving detector (11) emits laser light, and one of the six light spots is displayed on the receiving detector (4), and the marked position is A3 (X3, Y3); Step 4: During the communication process, the external laser beam is narrowed by the optical antenna (7), reflected by the second quick-reflection mirror (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 any deviation, the spot is adjusted to the A2 position by the second quick-reflection mirror (12); Step 5: The signal transmitting laser of the signal transmitting optical path 2 transmits laser light, which is collimated by the transmitting lens (5), then reflected by the quick reflector (9), passed through the second beam splitter (8), reflected by the beam splitter (2), reflected back to the beam splitter (2) by the special angle cone prism (1), passed through the beam splitter (2), collimated by the receiving lens (3), and forms a light spot on the window of the receiving detector (4). The angle of the quick reflector (9) is adjusted to adjust the position of the light spot to point A1 to complete the self-calibration of the signal transmitting branch 2. Since the special angle cone prism (1) makes the A1 coordinate 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 the normal sending and receiving 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 optical fiber (11-3), and after being collimated by the signal receiving lens (10), the laser light is reflected by the second beam splitter (8), the beam splitter (2), the special angle cone prism (1), and the beam splitter (2). After being collimated by the receiving lens (3), a signal receiving self-calibration light spot is formed on the receiving detector (4) window; the angle of the second beam splitter (8) is adjusted to adjust the position of the light spot to the A2 position, completing the self-calibration of the signal receiving optical path; because the special angle cone prism makes the A3 coordinate away from the A2 coordinate position, and because the signal receiving self-calibration is the off-axis core emission, the A3 coordinate is away from the A1 coordinate, and the light spot distance is d2, so the communication light spot and the emission and reception self-calibration light spots can be displayed at the same time without affecting the normal transmission and reception communication.

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