An inter-satellite laser link ground verification test system and method

Abstract

The embodiment of the application provides a kind of inter-satellite laser link ground verification test system and method, it is related to laser communication technical field, including: laser terminal module, for emitting first light beam to parallel light pipe module, and receiving second light beam returned by parallel light pipe module;Integrated light control module includes: light source unit for emitting second light beam to parallel light pipe module, light spot measurement unit for controlling light switch unit based on received first light beam, light switch unit for switching the on-off state of the light path of light source unit to parallel light pipe module under the control of light spot measurement unit;Parallel light pipe module includes: transceiver lens group for transmitting first light beam to energy beam splitter, energy beam splitter for transmitting first light beam to light spot measurement unit after splitting, and second light beam is sent to laser terminal module by transceiver lens group, and test system structure is simple and measurement accuracy is high.

Description

Technical Field

[0001] This application relates to the field of laser communication technology, and in particular to a ground verification and testing system and method for inter-satellite laser links. Background Technology

[0002] Verifying and testing the tracking and link establishment functions and performance of the laser terminal by setting up a laser link testing system on the ground is a key link and important guarantee for ensuring that the laser terminal can successfully establish and reconnect in orbit.

[0003] In related technologies, two collimators are typically used to build a laser link testing system. Devices such as optical attenuators are used to compensate for spatial transmission loss. Stray light inside the collimators is suppressed by using light shields, light-absorbing paper, or spraying black paint. Finally, a laser terminal is connected to each end of the two collimators to perform tests such as tracking and link establishment.

[0004] However, the dual collimator structure is relatively complex and costly. Furthermore, to overcome the doubled loss caused by the dual collimators, the laser terminal needs to emit a high-power beam, which leads to a surge in the intensity of stray light reflected within the collimators. This severely interferes with the laser terminal's recognition of the signal light, resulting in lower accuracy of the test results. Summary of the Invention

[0005] This invention provides a ground verification and testing system and method for inter-satellite laser links, which solves the problems of complex structure, high cost, large influence from stray light, and low measurement accuracy in related technologies.

[0006] In a first aspect, this application provides a ground verification and testing system for an inter-satellite laser link. The system includes a laser terminal module, an integrated optical control module, and a collimator module, wherein:

[0007] The aforementioned laser terminal module is used to adjust the bias angle of the emitted beam, emit a first beam to the aforementioned collimator module, and receive a second beam returned by the aforementioned collimator module.

[0008] The aforementioned integrated light control module includes a light source unit, a light spot measurement unit, and an optical switch unit. The light source unit is used to emit a second light beam to the aforementioned collimator module. The light spot measurement unit is used to control the optical switch unit based on the received first light beam. The optical switch unit is used to switch the on / off state of the optical path from the light source unit to the collimator module under the control of the light spot measurement unit.

[0009] The aforementioned collimator module includes a transceiver assembly and an energy beam splitter. The transceiver assembly is used to transmit the first beam to the energy beam splitter. The energy beam splitter is used to split the first beam and transmit it to the spot measurement unit, and to send the second beam to the laser terminal module through the transceiver assembly.

[0010] In some alternative implementations, the above-mentioned collimator module further includes a waveplate, a coupling lens, and a polarization-maintaining single-mode fiber;

[0011] The aforementioned energy beam splitter is specifically used to split the aforementioned first beam, transmit the split first sub-beam through the aforementioned waveplate to the aforementioned coupling lens, and transmit the split second sub-beam to the aforementioned spot measurement unit.

[0012] The waveplate is used to change the polarization direction of the first sub-beam and the second beam.

[0013] The coupling lens is used to couple the first sub-beam to the polarization-maintaining single-mode fiber when the emission direction of the first beam is in the direction of the optical axis center of the collimator module, and transmit it to the laser terminal module through the integrated optical control module, and transmit the second beam received through the polarization-maintaining single-mode fiber to the energy splitter through the waveplate.

[0014] In some optional implementations, the integrated light control module described above further includes a beam coupling unit;

[0015] The aforementioned optical switch unit is used to switch the on / off state of the optical path from the aforementioned light source unit to the aforementioned beam coupling unit under the control of the light spot measurement unit;

[0016] The aforementioned beam coupling unit is used to couple the aforementioned second beam to the aforementioned polarization-maintaining single-mode fiber, and to transmit the aforementioned first sub-beam to the aforementioned laser terminal module.

[0017] In some optional embodiments, the beam coupling unit is a circulator; the circulator includes a first port, a second port and a third port, the circulator receives the second beam through the first port and transmits it to the polarization-maintaining single-mode fiber through the second port, and receives the first sub-beam through the second port and transmits it to the laser terminal module through the third port.

[0018] In some alternative implementations, the polarization direction of the polarization-maintaining single-mode fiber is matched with the polarization direction of the waveplate so that the polarization characteristics of the first sub-beam and the second beam do not affect each other.

[0019] In some optional embodiments, the collimator module further includes a reflector; the energy beam splitter is used to split the first beam and then transmit it to the spot measurement unit through the reflector.

[0020] Secondly, this application provides a ground verification test method for inter-satellite laser links, applied to the aforementioned ground verification test system for inter-satellite laser links, the method comprising:

[0021] After aligning the optical axis center of the laser terminal module with that of the collimator module, the first beam is emitted, and the target offset angle is set.

[0022] The following first link connection test process is performed: the laser terminal module is set to scanning state, the integrated light control module is set to staring state, and the light spot measurement unit controls the light switch unit to switch the optical path from the light source unit to the collimator module to conduction state based on the received first beam; after the laser terminal module receives the second beam, the direction of the first beam is adjusted back to the direction of the optical axis center of the collimator module.

[0023] If the optical path from the light source unit to the collimator module is switched to the conducting state, and the time it takes for the spot measurement unit to detect the spot image based on the first beam reaches a preset time, then the first link connection test is determined to be successful.

[0024] In some optional implementations, the above-mentioned method of controlling the optical switch unit to switch the optical path from the light source unit to the collimator module into a conducting state based on the received first light beam by the light spot measurement unit includes:

[0025] After receiving the first beam, the light spot measurement unit outputs a control voltage to the optical switch unit.

[0026] After receiving the control voltage, the optical switch unit switches the optical path from the light source unit to the collimator module to the conducting state after a preset time interval; or, when the optical switch unit receives the control voltage a preset number of times, it switches the optical path from the light source unit to the collimator module to the conducting state.

[0027] In some optional embodiments, after receiving the second beam through the laser terminal module and adjusting the direction of the first beam back to the optical axis center direction of the collimator module, the method further includes:

[0028] Based on the time interval between the moment the laser terminal module emits the first beam and the moment it receives the second beam, and after the laser terminal module adjusts the direction of the first beam back to the optical axis center direction of the collimator module, the spot measurement unit detects the spot image and determines the link establishment time corresponding to the first link connection test.

[0029] In some optional implementations, the method further includes:

[0030] The laser terminal module is configured to emit the first beam, and the target offset angle is set.

[0031] Set the laser terminal module to staring mode, set the integrated light control module to scanning mode, set the optical path connection from the light source unit to the collimator module to periodic conduction, and perform the following second link connection test process: after receiving the second beam through the laser terminal module, adjust the direction of the first beam back to the optical axis center direction of the collimator module.

[0032] If the optical path from the light source unit to the collimator module is switched to the conducting state, and the duration for which the spot measurement unit detects the spot image based on the first beam reaches a preset duration, then the second link connection test is determined to be successful.

[0033] In this embodiment, a system for link testing based on the laser terminal under test and a single collimator is designed. The system has a simple structure and high cost-effectiveness. At the same time, since the transmission loss of a single collimator is reduced by half, the laser terminal does not need to emit a high-power beam, which effectively suppresses the influence of factors such as reflected stray light introduced by high-power emitted light on the testing process from the root, reduces the requirements for the collimator platform, and improves the accuracy of measurement. Furthermore, based on the integrated optical control module, the actual on-orbit dynamic tracking process is simulated by condition-triggered optical path control. The testing method is simple, has comprehensive application scenarios, and has high testing accuracy. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the first type of inter-satellite laser link ground verification test system provided in the embodiments of this application;

[0036] Figure 2A schematic diagram of the second type of inter-satellite laser link ground verification test system provided in the embodiments of this application;

[0037] Figure 3 A schematic diagram illustrating a possible design method for the polarization direction of a polarization-maintaining single-mode fiber and a spatial optical path, provided for an embodiment of this application;

[0038] Figure 4 This is a flowchart of a ground verification test method for an inter-satellite laser link provided in an embodiment of this application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0041] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two devices. Those skilled in the art can understand the specific meaning of the above term in this application based on the specific circumstances.

[0042] Verifying and testing the tracking and link establishment functions and performance of laser terminals by setting up a ground-based laser link testing system is a crucial step and important guarantee for ensuring successful on-orbit link establishment (i.e., link establishment) and re-linking (i.e., link re-acquisition). Related technologies typically utilize two collimators to build the laser link testing system. Devices such as optical attenuators are used to compensate for spatial transmission loss, and stray light within the collimators is suppressed using methods such as light shields, light-absorbing paper, or black paint. Finally, a laser terminal is connected to each end of the two collimators for tracking and link establishment tests.

[0043] However, the dual collimator structure is relatively complex and costly. Furthermore, to overcome the doubled loss caused by the dual collimators, the laser terminal needs to emit a high-power beam, which leads to a surge in the intensity of stray light reflected within the collimators. This severely interferes with the laser terminal's recognition of the signal light, resulting in lower accuracy of the test results.

[0044] Therefore, the structure of dual parallel light tubes in related technologies is relatively complex, the economic cost is high, they are greatly affected by stray light, and the test accuracy is not high.

[0045] Furthermore, if only a single collimator is used for tracking and link building tests, the light emitted by the collimator is initially located at the center of the optical axis, which cannot simulate the dynamic process of capturing the light and pulling it back to the center of the optical axis, thus leading to inaccurate test results.

[0046] In view of this, embodiments of this application provide a ground verification and testing system and method for inter-satellite laser links, used to simulate the dynamic acquisition, tracking, and link establishment process of laser communication terminals, and to perform performance tests such as link establishment and reconnection on the laser link. Specifically, a system for link testing based on the laser terminal under test and a single collimator is designed. The system has a simple structure and high cost-effectiveness. At the same time, since the transmission loss of a single collimator is reduced by half, the laser terminal does not need to emit a high-power beam, effectively suppressing the influence of factors such as reflected stray light introduced by high-power emitted light on the testing process from the root, reducing the requirements for the collimator platform and improving the accuracy of measurement. Furthermore, based on an integrated optical control module, condition-triggered optical path control is used to simulate the actual on-orbit dynamic acquisition and tracking process. The testing method is simple, has comprehensive application scenarios, and high testing accuracy.

[0047] In some embodiments, the system provided in this application is implemented based on a laser networking simulation verification platform, which can simplify the system structure complexity during ground testing and verification of laser terminals, improve the accuracy of function and performance measurement, enhance ground testing and verification capabilities, and has high cost-effectiveness and engineering application value.

[0048] In this embodiment of the application, the above-mentioned inter-satellite laser link ground verification test system and method are applicable to verifying the tracking, link establishment, and communication function performance of various types of laser terminals through a parallel test system built on the ground. It is a key link for the actual verification of laser terminals before they are in orbit, and can ensure that laser terminals can quickly establish and reconnect links in orbit.

[0049] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with reference to the accompanying drawings and specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0050] See Figure 1 As shown, the first type of inter-satellite laser link ground verification test system provided in this embodiment includes a laser terminal module, an integrated optical control module, and a collimator module, wherein:

[0051] The aforementioned laser terminal module is used to adjust the bias angle of the emitted beam, emit a first beam to the aforementioned collimator module, and receive a second beam returned by the aforementioned collimator module.

[0052] The aforementioned integrated light control module includes a light source unit, a light spot measurement unit, and an optical switch unit. The light source unit is used to emit a second light beam to the aforementioned collimator module. The light spot measurement unit is used to control the optical switch unit based on the received first light beam. The optical switch unit is used to switch the on / off state of the optical path from the light source unit to the collimator module under the control of the light spot measurement unit.

[0053] The aforementioned collimator module includes a transceiver assembly and an energy beam splitter. The transceiver assembly is used to transmit the first beam to the energy beam splitter. The energy beam splitter is used to split the first beam and transmit it to the spot measurement unit, and to send the second beam to the laser terminal module through the transceiver assembly.

[0054] In this embodiment, the laser terminal module has the function of adjusting the parameters corresponding to the emitted beam, including the wavelength, polarization state (i.e., polarization angle), power, bias angle and other parameters of the beam.

[0055] See Figure 2 As shown, this embodiment provides a second type of inter-satellite laser link ground verification test system. The laser terminal module may include a laser terminal and a control unit (i.e., a processor). The laser terminal is used to emit a beam of light to the collimator module and receive the beam of light from the collimator module. The processor is used to control the laser terminal, for example, to control the laser terminal to switch between scanning, capture (i.e., staring) and other modes.

[0056] At this time, a portion of the beam split by the energy splitter in the aforementioned collimator module (i.e., the first sub-beam) is transmitted to the processor of the aforementioned laser terminal module via the integrated optical control module, while the other portion (i.e., the second sub-beam) is transmitted to the aforementioned spot measurement unit.

[0057] In some embodiments, the system may further include a two-dimensional turntable, the two-dimensional state being used to fix the position of the laser terminal, and the processor being placed on another platform outside the two-dimensional turntable; optionally, the laser terminal in the laser terminal module of the present application can complete the parameter adjustment of the emitted beam by itself, or the two-dimensional state can be used to assist the laser terminal in completing the parameter adjustment of the emitted beam.

[0058] In some alternative implementations, the above-mentioned collimator module further includes a waveplate, a coupling lens, and a polarization-maintaining single-mode fiber;

[0059] Specifically, the energy beam splitter is used to split the first beam, transmit the split first sub-beam to the coupling lens through the waveplate, and transmit the split second sub-beam to the spot measurement unit.

[0060] The waveplate is used to change the polarization direction of the first sub-beam and the second beam.

[0061] The coupling lens is used to couple the first sub-beam to the polarization-maintaining single-mode fiber when the emission direction of the first beam is in the direction of the optical axis center of the collimator module, and transmit it to the laser terminal module through the integrated optical control module, and transmit the second beam received through the polarization-maintaining single-mode fiber to the energy splitter through the waveplate.

[0062] In some alternative implementations, an attenuator (switchable attenuator) is also included between the energy beam splitter and the transceiver assembly.

[0063] In some optional embodiments, the collimator module further includes a reflector; the energy beam splitter is used to split the first beam and then transmit it to the spot measurement unit through the reflector.

[0064] See Figure 2 As shown, in the above system, the collimator unit, along the optical path of the first beam, includes a transceiver lens group, an attenuator, an energy splitter, a waveplate, a coupling lens, and a polarization-maintaining single-mode fiber for transmitting and receiving beams, connected in sequence. It is used to realize the far-field simulation of the beam and has the functions of simulating the transmission, convergence and reception, and beam splitting of the far-field beam.

[0065] In some embodiments, the transceiver array may include a primary mirror, a secondary mirror, a third mirror, and a fast-reflecting mirror arranged in sequence; the types of the attenuator and energy beam splitter may be set according to requirements. For example, a -30dBm attenuator and a 99:1 beam splitter may be selected, that is, 99% of the light beam is split for transmission (i.e., the first sub-beam) and 1% of the light beam is split for detection (i.e., the second sub-beam).

[0066] In the above system, the transmission optical path of the beam in the collimator module is a spatial optical path, and the optical path from the laser terminal module to the collimator module for emitting the first beam is also a spatial optical path. The transmission path of the beam in the integrated optical control module is mainly an optical fiber path. The connection between the spot measurement unit and the optical switch unit is a circuit connection, that is, the spot measurement unit controls the optical switch unit through the output control unit.

[0067] In some optional implementations, the integrated light control module described above further includes a beam coupling unit;

[0068] The aforementioned optical switch unit is used to switch the on / off state of the optical path from the aforementioned light source unit to the aforementioned beam coupling unit under the control of the light spot measurement unit;

[0069] The aforementioned beam coupling unit is used to couple the aforementioned second beam to the aforementioned polarization-maintaining single-mode fiber, and to transmit the aforementioned first sub-beam to the aforementioned laser terminal module.

[0070] In some embodiments, the integrated optical control module is used to simulate another laser terminal (i.e., to emit a second beam) and then to perform a link establishment test with the laser terminal under test (i.e., the laser terminal module).

[0071] The aforementioned spot measurement unit is used to detect the first beam emitted by the laser terminal to the collimator module, and can be a spot measurement device such as a beam quality analyzer or a monitoring camera; the aforementioned light source unit is used to provide an emission light source for the collimator, and must meet the laser terminal module's requirements for the received beam power, and can be an external standard light source with switchable wavelength and polarization state, or a standard light source with an amplification module, and must always be in the on state; the aforementioned optical switch unit includes: an optical switch and its control unit, used to control the on / off state of the optical path (specifically the optical path from the light source unit to the beam coupling unit) between the light source unit and the aforementioned collimator module, when the optical switch is in the on state. When the optical switch is in the closed state, the optical path between the light source unit and the collimator module is connected. When the optical switch is in the closed state, the optical path between the light source unit and the collimator module is disconnected. The optical switch can be a MEMS (microelectromechanical system) optical switch, magneto-optical switch, or other fast-response optical switch device or chip. The beam coupling unit can be a circulator, bidirectional coupler, or other device, used to receive the beam emitted by the laser terminal through the optical path of the collimator module (i.e., the first sub-beam) and further transmit the beam to the laser terminal (i.e., the processor) for subsequent testing, and to couple the beam emitted by the light source unit (i.e., the second beam) into the collimator optical path.

[0072] The output of the aforementioned spot measurement unit is connected to the control unit of the optical switch. The driving voltage threshold of the optical switch control unit is correlated with the voltage value (i.e., control voltage) output by the spot measurement unit after detecting light. The conditions for triggering the optical switch unit to open and close are set via a host computer program. When the spot measurement unit detects the beam, it sends a signal (i.e., control voltage) to the control unit of the optical switch unit, controlling the opening and closing of the optical switch unit according to the set trigger conditions. Extending the opening time of the optical switch unit can simulate the situation where multiple adjustments to the tracking direction are required for stable tracking under actual working conditions. When the optical switch unit is open, the beam emitted by the light source unit can enter the collimator module through the beam coupling unit and be transmitted to the laser terminal through the collimator optical path.

[0073] See Figure 2As shown, in some optional embodiments, the beam coupling unit is a circulator; the circulator includes a first port (i.e., 1 in the figure), a second port (i.e., 2 in the figure) and a third port (i.e., 3 in the figure). The circulator receives the second beam through the first port and transmits it to the polarization-maintaining single-mode fiber through the second port, and receives the first sub-beam through the second port and transmits it to the laser terminal module through the third port for subsequent testing.

[0074] In some alternative implementations, the polarization direction of the polarization-maintaining single-mode fiber is matched with the polarization direction of the waveplate so that the polarization characteristics of the first sub-beam and the second beam do not affect each other.

[0075] Since the first beam emitted by the laser terminal and the second beam emitted by the light source unit are both transmitted through the polarization-maintaining single-mode fiber in the collimator module, in order to avoid the polarization characteristics of the first beam and the second beam from affecting each other, the polarization direction of the polarization-maintaining single-mode fiber used for transmitting and receiving beams in the collimator module should be matched with the polarization direction of the spatial optical path (i.e., the waveplate) so that the two opposing beams can propagate in the same fiber without affecting each other's polarization characteristics. Based on this, the polarization direction of the output beam of the integrated optical control module is designed in this application.

[0076] See Figure 3 As shown, this embodiment provides a possible design for the polarization direction of the polarization-maintaining single-mode fiber and the spatial optical path (i.e., waveplate). In the collimator module, the waveplate is a quarter-waveplate, with its fast axis set vertically and its slow axis set horizontally. The fast and slow axes of the polarization-maintaining single-mode fiber used for transmitting and receiving beams in the collimator module form a +45° angle with the fast and slow axes of the waveplate (i.e., rotated 45° counterclockwise relative to the quarter-waveplate). As shown, when the left-handed polarized light (first beam) emitted by the laser terminal passes through the quarter-waveplate, it becomes linearly polarized light aligned with the fast axis of the polarization-maintaining single-mode fiber and enters the fiber's fast axis for transmission. The beam direction (i.e., the second beam) in the integrated optical control module is designed to be aligned with the slow axis of the polarization-maintaining single-mode fiber. That is, the beam output from the slow axis of the polarization-maintaining single-mode fiber becomes left-handed circularly polarized light when viewed against the beam propagation direction after passing through the quarter-waveplate, thereby achieving simultaneous propagation of two opposing beams without affecting each other's polarization characteristics.

[0077] It should be noted that the above Figure 3 The design given is just an example. In actual implementation, the polarization direction of the polarization-maintaining single-mode fiber and the spatial optical path (i.e., waveplate) can be designed according to the actual situation. It is only necessary to ensure that the polarization directions of the two are matched so that the two beams do not affect each other in the same fiber.

[0078] The following describes the beam transmission process in the ground verification test system of the inter-satellite laser link:

[0079] The first beam emitted from the laser terminal to the collimator module passes sequentially through the transceiver lens group and attenuator in the collimator module, and is then split into a first sub-beam and a second sub-beam by the energy beam splitter.

[0080] The first sub-beam passes through a waveplate and a coupling lens in sequence, and is then transmitted through a polarization-maintaining single-mode fiber to the beam coupling unit of the integrated optical control module. After passing through the beam coupling unit, it is transmitted to the processor of the laser terminal module.

[0081] The second sub-beam is transmitted to the spot measurement unit via a reflector, so that the spot measurement unit sends a control voltage to the optical switch unit.

[0082] The second beam emitted by the light source unit passes sequentially through the optical switch unit (in the on state) and the beam coupling unit, and is transmitted to the polarization-maintaining single-mode fiber of the collimator module. It then passes sequentially through the coupling lens, waveplate, energy beam splitter, attenuator, and transceiver mirror group in the collimator module, and is transmitted to the laser terminal of the laser terminal module.

[0083] In this invention, the actual operating conditions of both ends in orbit can be equivalently simulated in the following way:

[0084] The light source unit in the integrated light control module consists of a standard light source or a "standard light source + amplification module". By adjusting the emission power of the standard light source or the power amplification factor of the amplification module, different emission power and return power under actual on-orbit conditions can be simulated equivalently, and the requirements of ground-based double-end docking sensitivity testing can be met.

[0085] The driving voltage threshold of the optical switch control unit is correlated with the voltage value output by the spot measurement unit after detecting light. Based on the tracking strategies of different laser terminal manufacturers, the conditions for triggering the opening and closing of the optical switch unit are set through the host computer program, that is, the tracking response time is set. The opening of the optical switch unit is controlled according to the set conditions. This can equivalently simulate the situation where multiple adjustments to the tracking direction are required to achieve stable tracking under actual on-orbit conditions, and equivalently simulate the response time of different laser terminal acquisition and tracking.

[0086] The light source unit is always on. When the light spot measurement unit detects light, it controls the light switch to turn on according to the set conditions. The light source unit and the collimator module are connected in the optical path. When the light switch unit is closed, the light source unit and the collimator module are disconnected in the optical path. This can be used to simulate the conditions under which the laser terminal captures light and returns it to the laser terminal at the other end, and the conditions under which the link is broken and the laser terminal recaptures the light.

[0087] Based on the aforementioned inter-satellite laser link ground verification test system structure, this application also provides an inter-satellite laser link ground verification test method, specifically including:

[0088] After aligning the optical axis center of the laser terminal module with that of the collimator module, the first beam is emitted, and the target offset angle is set.

[0089] The following first link connection test process is performed: the laser terminal module is set to scanning state, the integrated light control module is set to staring state, and the light spot measurement unit controls the light switch unit to switch the optical path from the light source unit to the collimator module to conduction state based on the received first beam; after the laser terminal module receives the second beam, the direction of the first beam is adjusted back to the optical axis center direction of the collimator module.

[0090] If the optical path from the light source unit to the collimator module is switched to the conducting state, and the time it takes for the spot measurement unit to detect the spot image based on the first beam reaches a preset time, then the first link connection test is determined to be successful.

[0091] In some embodiments, the first link connection test mentioned above refers to the link connection test process in which the laser terminal module is in a scanning state and the light-emitting unit in the integrated light control module is in a staring state.

[0092] In some embodiments, before the laser terminal module emits a first beam with a target bias angle to the collimator module, it is necessary to control the alignment of the optical axis center of the laser terminal module and the collimator module, and to set key parameters in the capture and link building process, such as the wavelength, polarization state (polarization angle), and power of the light emitted by the laser terminal module and the integrated optical control module, and to set the angles and positions of each unit in the collimator module, so that the parameters between the laser terminal module, the collimator module, and the integrated optical control module are matched.

[0093] In some embodiments, this application simulates different transmission scenarios in a space environment by setting the first beam to different offset angles (i.e., the target offset angles mentioned above) and performing the first link test process respectively. The specific value and number of offset angles are not limited in this application.

[0094] In some embodiments, after receiving the second beam, the laser terminal module follows the second beam and adjusts its direction back to the optical axis center direction of the collimator module.

[0095] In some embodiments, the duration for which the spot measurement unit detects the spot image based on the first beam refers to the continuous duration for which the spot image is detected; the preset duration can be set according to requirements, for example, it can be set to 60 seconds. If the spot measurement unit fails to continuously detect the spot image within the preset duration, it indicates that the test has failed. At this time, the optical switch unit can be switched to the off state, that is, the optical path from the light source unit to the collimator module can be switched to the disconnected state, and the first link connection test process can be re-executed.

[0096] In some optional implementations, the above-mentioned method of controlling the optical switch unit to switch the optical path from the light source unit to the collimator module into a conducting state based on the received first light beam by the light spot measurement unit includes:

[0097] After receiving the first beam, the light spot measurement unit outputs a control voltage to the optical switch unit.

[0098] After receiving the control voltage, the optical switch unit switches the optical path from the light source unit to the collimator module to the conducting state after a preset time interval; or, when the optical switch unit receives the control voltage a preset number of times, it switches the optical path from the light source unit to the collimator module to the conducting state.

[0099] In some embodiments, the specific values ​​of the preset duration and preset number of times can be set according to requirements, and this application does not impose any restrictions.

[0100] In some optional embodiments, after receiving the second beam through the laser terminal module and adjusting the direction of the first beam back to the optical axis center direction of the collimator module, the method further includes:

[0101] Based on the time interval between the moment the laser terminal module emits the first beam and the moment it receives the second beam, and after the laser terminal module adjusts the direction of the first beam back to the optical axis center direction of the collimator module, the spot measurement unit detects the spot image and determines the link establishment time corresponding to the first link connection test.

[0102] In some embodiments, during the first link connection test, the corresponding link establishment time also needs to be recorded. When determining this time, the time interval between the moment the laser terminal module emits the first beam and the moment it receives the second beam (hereinafter referred to as the target time interval for ease of explanation), and the spot image detected by the spot measurement unit after the laser terminal module adjusts the direction of the first beam back to the optical axis center direction of the collimator module (hereinafter referred to as the target spot image for ease of explanation), are considered simultaneously. Specifically, when the spot measurement unit determines that the target spot image is located at the center, the target time interval is used as the link establishment time corresponding to the first link connection test; otherwise, the target time interval measurement is determined to be incorrect, and a corresponding prompt message is generated to help the user determine the cause of the problem and make adjustments.

[0103] In some optional implementations, after confirming the success of the first link connection test based on the above method, a multiple link test and a communication function performance test can be performed simultaneously. Specifically, the multiple link test process involves switching the optical switch unit to the off state, i.e., disconnecting the optical path from the light source unit to the collimator module, and re-executing the first link connection test process. If the test result is successful, the multiple link test is considered passed. The communication function performance test process involves starting the communication function of the laser terminal module, causing the laser terminal model to emit a first signal, and performing a process similar to the first link connection test to obtain the corresponding test results.

[0104] The following section, using specific examples, explains the detailed implementation process of the above-mentioned ground verification test method for inter-satellite laser links. (See reference...) Figure 4 As shown:

[0105] S401: The processor that controls the above-mentioned two-dimensional turntable and laser terminal module controls the laser terminal to emit the first beam in the direction of the optical axis center of the collimator module, and sets the key parameters such as wavelength, polarization state, and power of the laser terminal to match those of the collimator module and the integrated optical control module.

[0106] S402, adjust the bias angle of the first beam of the laser terminal to the target bias angle;

[0107] In some embodiments, the target offset angle can be set according to requirements. In practice, the target offset angle can be set to different values, that is, the initial beam position is subjected to different parameters of deflection processing, and steps S402-S407 are repeated to simulate different transmission situations in the space environment.

[0108] For example, the initial pointing offset of the first beam's azimuth and elevation line of sight can be set to +3.0 mrad and -3.0 mrad, respectively.

[0109] S403, Set the laser terminal module to scanning mode and the integrated light control module to staring mode;

[0110] In some embodiments, the processor that controls the laser terminal module causes one end of the laser terminal to start scanning, i.e., to be in a scanning state.

[0111] In some embodiments, the light spot measurement unit is turned on and the optical switch unit is turned off, thereby disconnecting the optical path between the light source unit and the collimator module to simulate the initial pointing bias when the laser terminal stares; the light source unit is turned on and outputs a second beam; for example, the emitted light power of the second beam is 5dBm.

[0112] In some embodiments, if the light emitted by the standard light source itself cannot meet the sensitivity requirements of the laser terminal, an amplification module needs to be connected after the standard light source to simulate the actual on-orbit operating conditions, the light emission power and return power, and to meet the requirements of ground-based double-end docking sensitivity testing.

[0113] S404: When the light spot measurement unit detects light, it sends a signal (i.e., control voltage) to the control unit of the optical switch unit, and controls the optical switch unit to open according to the set triggering method. The light source unit emits a second beam of light into the optical path of the collimator module.

[0114] In some embodiments, the condition triggering method is set such that the control unit of the optical switch receives a certain number of set voltages from the spot measurement unit, or receives a set voltage from the spot measurement unit and then delays for a certain period of time before the optical switch unit can be turned on, in order to simulate the situation in actual working conditions where the tracking direction needs to be adjusted multiple times to achieve stable tracking.

[0115] S405: After the laser terminal scans the second beam returned by the collimator module, it automatically adjusts its direction to pull the first beam back to the optical axis center of the collimator module, so that the first beam enters the single-mode polarization-maintaining fiber of the collimator module.

[0116] At this point, both parties (i.e., the laser terminal and the integrated optical control module) have captured the beam emitted by the other, completing the capture, tracking and link establishment in the scanning state of the laser terminal.

[0117] S406: Calculate the time from the emission of the first beam from the laser terminal to the moment when both ends capture the beam emitted by the other and achieve stable tracking;

[0118] In some embodiments, the above time calculation is based on the telemetry data of the laser terminal under test (i.e., the time interval between the moment when the laser terminal module emits the first beam and the moment when it receives the second beam), and the spot position obtained by the spot measurement unit (i.e., the spot image is located at the center position) is used to assist in the judgment.

[0119] Furthermore, the initial line-of-sight pointing offset value (i.e., the value of the target offset angle) can be changed, and the average value can be obtained by taking multiple measurements.

[0120] S407, Determine whether the spot measurement unit continuously detects the spot image for a preset time after the optical switch unit is turned on; if yes, proceed to step S408, otherwise proceed to step S410.

[0121] If a spot image is detected continuously for a preset duration, the test is successful. The duration of the link establishment calculated in S406 is then used, and the complex link test process described in S408 is executed. Otherwise, the test fails, and the link connection test process is re-executed.

[0122] S408: Switch the optical switch unit to the off state and perform a relink test;

[0123] The reconnection test involves repeatedly executing steps S404-S406 above to test the laser terminal's reconnection and recapture function (i.e., the reconnection test).

[0124] S409: Enable communication function and perform performance test of laser terminal communication function;

[0125] After the above tracking and link establishment test is completed, the communication function of the laser terminal module is started, causing the laser terminal model to emit the first signal and perform a process similar to the first link connection test to obtain the corresponding test results.

[0126] S410, switch the optical switch unit to the off state and return to step S404.

[0127] In some optional implementations, the method provided in this application further includes:

[0128] The laser terminal module is configured to emit a first beam, and a target offset angle is set (the method for determining the target offset angle is similar to that used in the first link connection test process).

[0129] Set the laser terminal module to staring mode, set the integrated light control module to scanning mode, set the optical path connection from the light source unit to the collimator module to periodic conduction, and perform the following second link connection test process: after receiving the second beam through the laser terminal module, adjust the direction of the first beam back to the optical axis center direction of the collimator module.

[0130] If the optical path from the light source unit to the collimator module is switched to the conducting state, and the duration for which the spot measurement unit detects the spot image based on the first beam reaches a preset duration, then the second link connection test is determined to be successful.

[0131] In some embodiments, the second link connection test refers to the link connection test process in which the laser terminal module is in a staring state and the light-emitting unit in the integrated light control module is in a scanning state. Since the specific process of the first link connection test is similar to that of the first link connection test described above, please refer to the process of steps S405-S409 above, and will not be described in detail here.

[0132] In some embodiments, setting the optical path connection state from the light source unit to the collimator module to be periodically on means that the optical switch control unit is turned on once every certain period of time (the time can be set according to the requirements), and each time it is turned on for a fixed time (the time can be set according to the requirements), in order to simulate the initial pointing bias and scanning process of the laser terminal scanning.

[0133] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0134] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A ground verification and testing system for inter-satellite laser links, characterized in that, The system includes a laser terminal module, an integrated optical control module, and a collimator module, wherein: The laser terminal module is used to adjust the bias angle of the emitted beam, emit a first beam towards the collimator module, and receive a second beam returned by the collimator module. The integrated light control module includes a light source unit, a light spot measurement unit, and an optical switch unit. The light source unit is used to emit a second light beam to the collimator module. The light spot measurement unit is used to control the optical switch unit based on the received first light beam. The optical switch unit is used to switch the on / off state of the optical path from the light source unit to the collimator module under the control of the light spot measurement unit. The collimator module includes a transceiver assembly and an energy beam splitter. The transceiver assembly is used to transmit the first beam to the energy beam splitter. The energy beam splitter is used to split the first beam and transmit it to the spot measurement unit, and to send the second beam to the laser terminal module through the transceiver assembly.

2. The system according to claim 1, characterized in that, The collimator module also includes a waveplate, a coupling lens, and a polarization-maintaining single-mode fiber. The energy beam splitter is specifically used to split the first beam, transmit the split first sub-beam through the waveplate to the coupling lens, and transmit the split second sub-beam to the spot measurement unit. The waveplate is used to change the polarization direction of the first sub-beam and the second beam; The coupling lens is used to couple the first sub-beam to the polarization-maintaining single-mode fiber when the emission direction of the first beam is in the direction of the optical axis center of the collimator module, and transmit it to the laser terminal module through the integrated optical control module, and to transmit the second beam received through the polarization-maintaining single-mode fiber to the energy splitter through the waveplate.

3. The system according to claim 2, characterized in that, The integrated optical control module also includes a beam coupling unit; The optical switch unit is used to switch the on / off state of the optical path from the light source unit to the beam coupling unit under the control of the light spot measurement unit; The beam coupling unit is used to couple the second beam to the polarization-maintaining single-mode fiber and to transmit the first sub-beam to the laser terminal module.

4. The system according to claim 3, characterized in that, The beam coupling unit is a circulator; the circulator includes a first port, a second port and a third port. The circulator receives the second beam through the first port and transmits it to the polarization-maintaining single-mode fiber through the second port, and receives the first sub-beam through the second port and transmits it to the laser terminal module through the third port.

5. The system according to claim 2, characterized in that, The polarization direction of the polarization-maintaining single-mode fiber is matched with the polarization direction of the waveplate so that the polarization characteristics of the first sub-beam and the second beam do not affect each other.

6. The system according to any one of claims 1 to 5, characterized in that, The collimator module also includes a reflector; the energy splitter is used to split the first beam and then transmit it to the spot measurement unit through the reflector.

7. A ground verification test method for inter-satellite laser links, applied to the ground verification test system for inter-satellite laser links as described in any one of claims 1 to 6, characterized in that, The method includes: After aligning the laser terminal module with the optical axis center of the collimator module, the first beam is emitted, and the target offset angle is set. The following first link connection test process is performed: the laser terminal module is set to scanning state, the integrated light control module is set to staring state, and the light spot measurement unit controls the light switch unit to switch the optical path from the light source unit to the collimator module to the conducting state based on the received first beam; after the laser terminal module receives the second beam, the direction of the first beam is adjusted back to the direction of the optical axis center of the collimator module. If the optical path from the light source unit to the collimator module is switched to the conducting state, and the duration for which the spot measurement unit detects the spot image based on the first beam reaches a preset duration, then the first link connection test is determined to be successful.

8. The method according to claim 7, characterized in that, The step of controlling the optical switch unit to switch the optical path from the light source unit to the collimator module to a conducting state based on the received first beam, using the light spot measurement unit, includes: After receiving the first beam, the spot measurement unit outputs a control voltage to the optical switch unit. After receiving the control voltage, the optical switch unit switches the optical path from the light source unit to the collimator module to the conducting state after a preset time interval; or, when the number of times the optical switch unit receives the control voltage reaches a preset number, it switches the optical path from the light source unit to the collimator module to the conducting state.

9. The method according to claim 7, characterized in that, After receiving the second beam through the laser terminal module and adjusting the direction of the first beam back to the optical axis center direction of the collimator module, the method further includes: Based on the time interval between the moment the laser terminal module emits the first beam and the moment it receives the second beam, and after the laser terminal module adjusts the direction of the first beam back to the optical axis center direction of the collimator module, the spot measurement unit detects the spot image and determines the link establishment time corresponding to the first link connection test.

10. The method according to claim 7, characterized in that, The method further includes: The laser terminal module is configured to emit a first beam, and the target offset angle is set. Set the laser terminal module to staring mode, set the integrated light control module to scanning mode, set the optical path connection from the light source unit to the collimator module to periodic conduction, and perform the following second link connection test process: after receiving the second beam through the laser terminal module, adjust the direction of the first beam back to the optical axis center direction of the collimator module; If the optical path from the light source unit to the collimator module is switched to the conducting state, and the duration for which the spot measurement unit detects the spot image based on the first beam reaches a preset duration, then the second link connection test is determined to be successful.

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