Laser communication ground test apparatus, system and method

Abstract

The application relates to the technical field of laser communication, and provides a laser communication ground test device, system and method.The device comprises a beam-reducing optical unit, a first dichroic mirror, a second dichroic mirror, a beacon light source, a receiving detector, a voice coil motor, a beam splitter, a tracking camera and a transmitting / receiving module; the first dichroic mirror is arranged at a light beam outlet of the beam-reducing optical unit, and separates a light beam into a first light beam and a second light beam; the second dichroic mirror is arranged at a first light beam outlet, and the beacon light source and the receiving detector are respectively arranged at two light beam outlets of the second dichroic mirror; the voice coil motor is provided with a fast mirror, the fast mirror is arranged at a second light beam outlet, the beam splitter is arranged at a reflection outlet of the fast mirror, and the light beam is separated to the tracking camera and the transmitting / receiving module; the beacon light source and the receiving detector are used to realize coarse alignment with a measured laser communication load, the fast mirror and the tracking camera are used for tracking detection, and the transmitting / receiving module is used for interaction with the measured laser communication load, so that the test requirements of different loads are realized.

Description

Technical Field

[0001] This invention relates to the field of laser communication technology, and in particular to a laser communication ground testing device, system and method. Background Technology

[0002] With the development of aerospace communication technology, space laser communication technology, with its advantages of small beam divergence angle, good directivity, small antenna size, large communication capacity, low power consumption, and lightweight design, has become an important development direction in the field of satellite communication. Light waves, as the transmission medium, possess characteristics such as no absorption and scattering, low transmission loss, and strong resistance to electromagnetic interference in a vacuum environment. This makes laser communication far superior to traditional radio frequency microwave communication in terms of system cost-effectiveness, transmission rate, and security performance, demonstrating promising engineering application prospects. In recent years, as this technology has gradually moved from theoretical verification to large-scale engineering applications, the number of satellite launch missions carrying laser communication payloads has been increasing, placing more stringent requirements on the ground testing and system cascade testing of laser communication payloads.

[0003] However, with the increasing transmission frequency of laser communication terminals and the diversification of payload models, existing testing methods rely on dedicated testing equipment tied to satellite platforms, lacking versatility. This makes it difficult to efficiently support wireless joint debugging and testing between different satellite platforms and various laser communication units, affecting satellite development cycles and test coverage. Therefore, how to achieve wireless joint debugging and testing between various laser communication payloads and satellite platforms has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a ground testing device, system, and method for laser communication, which addresses the shortcomings of existing testing equipment in terms of poor versatility and difficulty in adapting to the joint debugging and testing requirements of various laser communication payloads, and enables wireless joint debugging and testing between different satellite platforms and laser communication payloads.

[0005] This invention provides a ground-based laser communication testing device for testing laser communication payloads under test. The device includes:

[0006] A beam-constricting optical unit is used to receive the laser beam emitted from the laser communication payload under test and to perform beam constriction.

[0007] The first dichroic mirror is disposed on the beam output path of the beam-constricting optical unit and is used to separate the incident laser beam into a first beam and a second beam.

[0008] The first alignment unit includes a second dichroic mirror, a beacon light source, and a receiver detector. The second dichroic mirror is disposed on the first beam output path of the first dichroic mirror. The beacon light source and the receiver detector are respectively located on two output beam paths of the second dichroic mirror. The beacon light emitted by the beacon light source is expanded by the second dichroic mirror, the first dichroic mirror, and the beam-shrinking optical unit before being emitted to cover the laser communication payload under test. The receiver detector is used to receive the laser beam emitted by the laser communication payload under test to achieve coarse alignment with the laser communication payload under test.

[0009] The second alignment unit includes a voice coil motor, a beam splitter, a tracking camera, and a transmitter / receiver module. The voice coil motor is equipped with a fast-reflecting mirror, which is positioned on the second beam output path of the first dichroic mirror. The beam splitter is positioned on the beam reflection output path of the fast-reflecting mirror, used to separate the beam to the tracking camera and the transmitter / receiver module. The tracking camera is used to receive the separated beam to track and detect the laser communication payload under test. The transmitter / receiver module is used to transmit test light signals to the laser communication payload under test and / or receive communication light signals emitted by the laser communication payload under test.

[0010] According to the present invention, a laser communication ground testing device is provided, wherein the beam-shrinking optical unit includes an off-axis primary mirror and an off-axis secondary mirror disposed on the beam path of the off-axis primary mirror, and the first dichroic mirror is located on the beam path of the off-axis secondary mirror.

[0011] According to the present invention, a laser communication ground testing device is provided, wherein the first dichroic mirror is used to reflect a first beam of visible light and transmit a second beam of communication light, or to transmit a first beam of visible light and reflect a second beam of communication light.

[0012] According to the present invention, a laser communication ground testing device is provided, wherein the first dichroic mirror has a first film system that reflects visible light and transmits communication light, wherein the first film system has a reflectivity of greater than or equal to 93% for the visible light band and a transmittance of greater than or equal to 92% for the communication light band.

[0013] According to the laser communication ground testing device provided by the present invention, the second dichroic mirror has a second film system, and the second film system has a reflectivity of greater than or equal to 70% for beacon light.

[0014] The present invention also provides a laser communication ground testing system, comprising the laser communication ground testing device described in any one of the above claims, and:

[0015] The adjustment platform is on which the laser communication ground testing device is mounted;

[0016] The control unit is electrically connected to the first alignment unit, the second alignment unit, and the adjustment platform, respectively. The control unit is used to control the movement of the adjustment platform according to the detection signal of the first alignment unit to achieve coarse tracking of the laser communication payload under test. The control unit is also used to control the voice coil motor to drive the fast-reflecting mirror to move according to the position information measured by the tracking camera in the second alignment unit to achieve fine tracking of the laser communication payload under test.

[0017] The present invention also provides a calibration method for a laser communication ground test device using any one of the above-described methods, comprising:

[0018] A reflective element is placed in the incident optical path of the beam-contracting optical unit;

[0019] The first alignment unit is calibrated by using the reflective element to reflect the beacon light emitted by the beacon light source back to the receiving detector, thereby completing the optical axis calibration between the beacon light source and the receiving detector in the first alignment unit.

[0020] The second alignment unit is calibrated by using the reflective element to reflect the debugging light emitted by the transmitting / receiving module back to the tracking camera, thereby completing the optical axis calibration between the transmitting / receiving module and the tracking camera in the second alignment unit.

[0021] According to the calibration method of a laser communication ground testing device provided by the present invention, the reflective element is a corner cube prism; the calibration of the first alignment unit includes:

[0022] Place the cornerstone prism in the incident light path of the beam-constricting optical unit;

[0023] The beacon light source is turned on, and the beacon light source emits beacon light. The beacon light is expanded by the second dichroic mirror, the first dichroic mirror, and the beam-shrinking optical unit before being emitted to the cornerstone prism.

[0024] The cornerstone prism reflects the beacon light back, and after passing through the beam-shrinking optical unit, the first dichroic mirror, and the second dichroic mirror, it is incident on the receiving detector.

[0025] By adjusting the position of the receiving detector until the converging light spot formed on the receiving detector is located at the center of the target surface of the receiving detector, the optical axis calibration between the beacon light source and the receiving detector in the first alignment unit is completed.

[0026] According to the calibration method of a laser communication ground testing device provided by the present invention, the reflecting element is a corner cube prism; the calibration of the second alignment unit includes:

[0027] Adjust the positions of the transmitting / receiving module and the beam splitter so that the debugging light emitted by the transmitting / receiving module passes through the beam splitter and enters the center of the fast-reflecting mirror;

[0028] The direction of the fast-reflecting mirror is adjusted by the voice coil motor so that the optical axis of the adjustment light emitted from the fast-reflecting mirror and the beacon light emitted from the first dichroic mirror coincides.

[0029] The corner cube prism is placed in the incident light path of the beam-shrinking optical unit. The adjustment light is expanded by the beam splitter, the fast-reflecting mirror, the first dichroic mirror, and the beam-shrinking optical unit before exiting to the corner cube prism.

[0030] The corner prism reflects the adjustment light back, and after being condensed by the beam-shrinking optical unit, the first dichroic mirror, the fast-reflecting mirror, and the beam splitter, it is incident on the tracking camera.

[0031] By adjusting the position of the tracking camera until the converging light spot formed by the tracking camera is located at the zero reference position of the tracking camera, the optical axis calibration between the transmitting / receiving module and the tracking camera in the second alignment unit is completed.

[0032] The present invention also provides a ground-based laser communication testing method, based on the ground-based laser communication testing apparatus described in any one of the above claims, the method comprising:

[0033] The beacon light source is turned on, and the beacon light source emits beacon light. The beacon light is expanded by the second dichroic mirror, the first dichroic mirror, and the beam-shrinking optical unit before being emitted to the laser communication payload under test.

[0034] The receiver detector receives the light beam returned from the laser communication payload under test and emitted through the beam-shrinking optical unit, the first dichroic mirror, and the second dichroic mirror, and the exit port characteristics of the laser communication payload under test are displayed in the field of view of the receiver detector.

[0035] The tracking camera acquires the current coordinate position of the beam returned from the laser communication payload under test.

[0036] Based on the deviation between the current coordinate position and the zero reference position, the beam direction of the fast-reflecting mirror is adjusted by the voice coil motor to lock the current coordinate position at the zero reference position;

[0037] The transmitting / receiving module is used to perform a transmit / receive test with the laser communication payload under test.

[0038] The laser communication ground testing device provided by this invention uses a beam-shrinking optical unit to shrink the emitted beam of the laser communication payload under test, and uses a first dichroic mirror to separate the beam before it is incident on a first alignment unit and a second alignment unit. The first alignment unit uses a beacon light source and a receiver detector to achieve coarse alignment with the laser communication payload under test, while the second alignment unit uses a fast-reflecting mirror and a tracking camera to track and detect the beam. It also interacts with the laser communication payload under test via a transmit / receive module to test the optical and communication optical signals. Thus, by integrating coarse alignment, fine tracking and detection, and communication testing functions into one unit, it can complete wireless joint testing with different types of laser communication payloads without being tied to a specific satellite platform. This effectively solves the problem of insufficient versatility caused by the reliance on dedicated platforms in traditional testing equipment, and can provide a testing platform for various laser communication payloads, thereby effectively supporting the testing needs of different payloads during satellite development. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of the laser communication ground testing device provided by the present invention.

[0041] Figure 2 This is a schematic diagram of the structure of the transmit / receive module provided by the present invention.

[0042] Figure 3 This is a flowchart illustrating the calibration method for the laser communication ground testing device provided by the present invention.

[0043] Figure 4 This is a flowchart illustrating the laser communication ground testing method provided by the present invention.

[0044] Figure label:

[0045] 101. Off-axis primary mirror; 102. Off-axis secondary mirror; 103. First dichroic mirror; 104. Second dichroic mirror; 105. Beacon light source; 106. Receiver detector; 107. Voice coil motor; 108. Beam splitter; 109. Transmitter / receiver module; 1010. Tracking camera;

[0046] 1091. Collimating coupling lens; 1092. First polarization-maintaining fiber; 1093. Polarization-maintaining fiber circulator; 1094. First polarization-maintaining fiber U-shaped stage; 1095. Filter; 1096. Second polarization-maintaining fiber U-shaped stage; 1097. Second polarization-maintaining fiber. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0050] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0051] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0052] The following is combined with Figures 1-4 The present invention describes a laser communication ground testing apparatus, system, and method.

[0053] An embodiment of the first aspect of the present invention provides a ground-based testing device for laser communication, which is used to test a laser communication payload under test, such as... Figure 1 As shown, the device includes a beam-shrinking optical unit, a first dichroic mirror 103, a first alignment unit, and a second alignment unit.

[0054] The beam-shrinking optical unit is used to receive the laser beam emitted from the laser communication payload under test and to perform beam-shrinking processing on the beam. It should be noted that since the diameter of the beam emitted from the laser communication payload is relatively large, the beam-shrinking optical unit can reduce the beam diameter to make it suitable for the size of optical components in the subsequent optical path, facilitating transmission, beam splitting, and detection within the device.

[0055] The first dichroic mirror 103 is disposed on the beam exit path of the beam-shrinking optical unit and is used to separate the incident laser beam into a first beam and a second beam. After being processed by the beam-shrinking optical unit, the laser beam is incident on the first dichroic mirror 103, which is used to separate the incident laser beam into a first beam and a second beam according to wavelength. For example, the first beam can be in the visible light band and is mainly used for alignment; the second beam can be in the communication band and is mainly used for signal transmission.

[0056] The first alignment unit is used to achieve coarse alignment with the laser communication payload under test. The first alignment unit includes a second dichroic mirror 104, a beacon light source 105, and a receiver detector 106. The second dichroic mirror 104 is disposed on the first beam output path of the first dichroic mirror 103, and the beacon light source 105 and the receiver detector 106 are respectively located on the two output beam paths of the second dichroic mirror 104. The beacon light emitted by the beacon light source 105 is expanded by the second dichroic mirror 104, the first dichroic mirror 103, and the beam-shrinking optical unit before being emitted to cover the laser communication payload under test. This process is equivalent to the device actively emitting a large spot of light as a signal lamp to cover and locate the target (the laser communication payload under test). The receiver detector 106 is used to receive the laser beam emitted by the laser communication payload under test to achieve coarse alignment with the laser communication payload under test.

[0057] The second alignment unit includes a voice coil motor 107, a beam splitter 108, a tracking camera 1010, and a transmit / receive module 109. The voice coil motor 107 is equipped with a fast-reflecting mirror, which is driven by the voice coil motor 107 and can perform high-speed, high-precision two-dimensional angle deflection. The fast-reflecting mirror is located on the second beam output path of the first dichroic mirror 103 and is used to receive the second beam separated by the first dichroic mirror 103. The beam splitter 108 is located on the beam reflection output path of the fast-reflecting mirror and is used to further separate the beam reflected by the fast-reflecting mirror and guide it to the tracking camera 1010 and the transmit / receive module 109 respectively. The tracking camera 1010 is used to receive the separated beams to track and detect the laser communication payload under test. The transmit / receive module 109 is used to transmit test light signals to the laser communication payload under test and / or receive communication light signals emitted by the laser communication payload under test.

[0058] The working process of the testing device in this embodiment is as follows:

[0059] The beacon light (usually visible light with a large divergence angle) emitted by the beacon light source 105 is reflected (or transmitted) by the second dichroic mirror 104 and then incident on the first dichroic mirror 103. After being expanded by the first dichroic mirror 103 and the beam-shrinking optical unit, it is emitted to form a light cone with a large coverage area, so as to ensure that it can cover and scan the laser communication payload under test at a distance.

[0060] The laser beam emitted from the laser communication payload under test (which may contain beacon or communication light) passes through the beam-shrinking optical unit and the first dichroic mirror 103. The first beam is then guided to the second dichroic mirror 104 and received by the receiving detector 106. By capturing the beam emitted from the laser communication payload under test, the receiving detector 106 can display the positional characteristics of the payload's output port within its field of view. When the beam from the laser communication payload under test falls into the field of view of the receiving detector 106, coarse alignment is completed.

[0061] Based on coarse alignment, when receiving signals from the laser communication payload under test, the communication beam emitted by the payload passes sequentially through the beam-shrinking optical unit, the first dichroic mirror 103, and the fast-reflecting mirror, reaching the beam splitter 108. The beam splitter 108 transmits (or reflects) a portion of the energy to the transmit / receive module 109 for signal reception and demodulation; simultaneously, it reflects (or transmits) another portion of the energy to the tracking camera 1010. The tracking camera 1010 receives the separated beam and detects its arrival angle in real time, thereby performing high-precision tracking and detection of the laser communication payload under test. When the beam's position on the tracking camera 1010 deviates, the voice coil motor 107 can be driven to adjust the direction of the fast-reflecting mirror based on this deviation, achieving closed-loop tracking and ensuring the beam always enters the transmit / receive module 109 stably.

[0062] When transmitting a signal to the laser communication payload under test, the test optical signal emitted by the transmitting / receiving module 109 passes sequentially through the beam splitter 108, the fast reflector, the first dichroic mirror 103, and the beam-expanding unit in the opposite direction to the receiving path before being emitted to the laser communication payload under test, thereby completing the uplink transmission of the communication optical signal.

[0063] The laser communication ground testing device provided in this embodiment of the invention uses a beam-shrinking optical unit to shrink the emitted beam of the laser communication payload under test, and uses a first dichroic mirror 103 to separate the beam and then incident it onto a first alignment unit and a second alignment unit respectively. The first alignment unit uses a beacon light source 105 and a receiver detector 106 to achieve coarse alignment with the laser communication payload under test. The second alignment unit uses a fast-reflecting mirror and a tracking camera 1010 to track and detect the beam, and interacts with the laser communication payload under test via a transmit / receive module 109 to test the optical and communication optical signals. Thus, by integrating coarse alignment, fine tracking and detection, and communication testing functions into one unit, it can complete wireless joint testing with different types of laser communication payloads without being tied to a specific satellite platform. This effectively solves the problem of insufficient versatility caused by the reliance on dedicated platforms in traditional testing equipment, and can provide a testing platform for various laser communication payloads, thereby effectively supporting the testing needs of different payloads during satellite development.

[0064] In one embodiment of the present invention, such as Figure 1 As shown, the beam-constricting optical unit adopts a reflective structure, specifically including an off-axis primary mirror 101 and an off-axis secondary mirror 102 disposed on the beam path of the off-axis primary mirror 101. The first dichroic mirror 103 is located on the beam path of the off-axis secondary mirror 102. The off-axis reflective structure can avoid central obstruction, improve energy utilization and imaging quality, and has no chromatic aberration, making it suitable for broadband laser transmission.

[0065] To ensure the optical performance of the beam-shrinking optical unit, a Zygo interferometer can be used to install and adjust the off-axis primary mirror 101 and off-axis secondary mirror 102 during the assembly and adjustment process. Interferometer testing showed that the RMS value of the system wavelet aberration of the entire beam-shrinking optical unit is better than 21 nm.

[0066] In this embodiment, the off-axis primary mirror 101 has an aperture of 120 mm and a focal length of 960 mm; the off-axis secondary mirror 102 has an aperture of 24 mm and a focal length of 96 mm. The combination of the off-axis primary mirror 101 and the off-axis secondary mirror 102 constitutes a 5x beam-shrinking system, meaning that the diameter of the laser beam incident on the beam-shrinking optical unit will be reduced to one-fifth of its original size after passing through this system (or expanded to five times its original size when used in reverse).

[0067] Furthermore, the wavefront aberration RMS introduced by the off-axis primary mirror 101 is better than 12.656 nm, and the wavefront aberration RMS introduced by the off-axis secondary mirror 102 is also better than 12.656 nm, laying a good foundation for the entire beam-shrinking optical unit to achieve a system wavefront aberration better than 21 nm.

[0068] In one embodiment of the present invention, the first dichroic mirror 103 is used to reflect a first beam of light in the visible light band and transmit a second beam of light in the communication light band, or to transmit a first beam of light in the visible light band and reflect a second beam of light in the communication light band.

[0069] It is understood that the wavelength selection of the first dichroic mirror 103 can be specifically set. It can be configured to reflect the first beam of visible light and transmit the second beam of communication light. The first dichroic mirror 103 can be coated with a first film system with corresponding functions. Conversely, it can also transmit the first beam of visible light and reflect the second beam of communication light.

[0070] In this embodiment, the first dichroic mirror 103 reflects the visible light band and transmits the communication light band; the first dichroic mirror 103 has a first film system that reflects the visible light band and transmits the communication light band.

[0071] For example, the first dichroic mirror 103 can be designed to reflect visible light in the 400nm~800nm ​​band and transmit communication light in the 1550nm±100nm band. Accordingly, the first dichroic mirror 103 is coated with a first film system, which has high reflectivity in the 400nm~800nm ​​band and high transmission characteristics in the 1550nm±100nm band. To ensure optical path transmission efficiency, the first film system has a reflectivity greater than or equal to 93% for the visible light band (400nm~800nm) and a transmittance greater than or equal to 92% for the communication light band (1550nm±100nm). Based on this, when the communication beam passes through the first dichroic mirror 103, the wavefront aberration introduced by the mirror itself is better than 42nm. Furthermore, when the communication optical band is narrowed to the range of 1550nm±30nm, the transmittance of the first film system to the communication optical band can be increased to greater than or equal to 95% to meet the requirements of higher performance communication testing.

[0072] For example, the surface accuracy of the first dichroic mirror 103 is better than 1 / 40λ, where λ is the test wavelength, which can be 632.8nm.

[0073] In one embodiment of the present invention, the second dichroic mirror 104 is used to transmit a first band of the first light beam and reflect a second band of the first light beam; or, to reflect a first band of the first light beam and transmit a second band of the first light beam; wherein the second band is the band of the beacon light.

[0074] In this embodiment, the second dichroic mirror 104 transmits light through the first band and reflects light through the second band. The beacon light source 105 is located on the reflected light path of the second dichroic mirror 104, and the receiving detector 106 is located on the transmitted light path of the second dichroic mirror 104.

[0075] During operation, the beacon light emitted by the beacon light source 105 is reflected by the second dichroic mirror 104 and then incident on the first dichroic mirror 103. After being reflected by the first dichroic mirror 103 and expanded by the beam-shrinking optical unit, it is emitted to illuminate the laser communication payload under test at the far end.

[0076] The laser beam emitted from the laser communication payload under test (which may contain beacon or communication light) is condensed by the beam-shrinking optical unit, reflected by the first dichroic mirror 103, and then transmitted through the second dichroic mirror 104 before finally being received by the receiving detector 106. The receiving detector 106 can be a visible light camera, which captures the laser beam emitted from the laser communication payload under test and displays the positional characteristics of its exit port within its field of view to achieve coarse alignment.

[0077] In one embodiment of the present invention, the second dichroic mirror 104 has a second film system, the second dichroic mirror 104 transmits the first band and reflects the second band (beacon light).

[0078] For example, the second dichroic mirror 104 may be designed to transmit through a first wavelength band of 400nm to 600nm and reflect through a second wavelength band (beacon light) of 671nm ± 10nm. Accordingly, the second dichroic mirror 104 is coated with a second film system, that is, the second film system has high transmission characteristics in the 400nm to 600nm range and high reflection characteristics in the 671nm ± 10nm range.

[0079] Optionally, the second film system has a reflectivity of 70% or greater for beacon light.

[0080] In this embodiment, the second film system has a transmittance of ≥85% for the first band (400nm~600nm) and a reflectance of ≥70% for the second band (beacon light); based on this, the surface profile accuracy of the second dichroic mirror 104 is better than 1 / 40λ; the wavefront aberration of the second dichroic mirror 104 is better than 42nm.

[0081] It should be noted that the second film system coated on the second dichroic mirror 104 is designed to have a transmittance of greater than or equal to 70% for the beacon light band, so that the optical axis can be self-collimated using the reflective element during device calibration. Specifically, during calibration, a reflective element is placed in the incident light path of the beam-shrinking optical unit. The beacon light emitted by the beacon light source 105 is reflected sequentially by the second dichroic mirror 104 and the first dichroic mirror 103 before entering the beam-shrinking optical unit. After beam expansion, it exits to the reflective element. The reflective element reflects the beacon light back along the original path. The returned beam is shrunken by the beam-shrinking optical unit and reflected by the first dichroic mirror 103 before being incident again on the second dichroic mirror 104. At this time, the second film system allows a small amount of beacon light to pass through and reach the receiving detector 106, thereby achieving optical axis calibration between the beacon light source 105 and the receiving detector 106 in the first alignment unit.

[0082] In one embodiment of the present invention, a beacon light source 105 is used to generate beacon light to illuminate the laser communication payload under test and achieve rapid alignment. To ensure alignment accuracy and spot quality, the beacon light is configured as a collimated beam output with an operating wavelength of 671 nm ± 10 nm.

[0083] For example, the beacon light source 105 can be a laser of model MLL-U-671-SM manufactured by Changchun New Industries Optoelectronic Technology Co., Ltd., with an output power range of 1~250mW. The laser has a wavelength accuracy of 671nm±1nm, ensuring the beacon light wavelength remains stable within the target wavelength range; the laser's output interface uses an FC / APC single-mode fiber optic connector. The laser's energy stability is better than 5% within 4 hours of operation, meaning the power fluctuation is less than ±5%, thus ensuring alignment stability during long-term testing.

[0084] In one embodiment of the present invention, the receiving detector 106 employs a visible light camera to receive the beam returned by the laser communication payload under test, thereby achieving coarse alignment. The visible light camera consists of four lenses. The optical system of the visible light camera has a focal length of 30mm, a light-gathering aperture of 15mm, and an imaging spectral range of 400nm to 600nm, covering the visible light band where the beacon light is located. The first lens is an aperture stop. The overall surface accuracy of the four-lens combination system is better than 63.28nm, ensuring clear imaging and position detection of the returned beam.

[0085] In one embodiment of the present invention, a voice coil motor 107 is used to drive a fast reflector to achieve high-speed and high-precision beam pointing adjustment, thereby completing the precise tracking of the laser communication payload under test. For example, the voice coil motor 107 can be a two-axis voice coil motor manufactured by NEWPORT, model 320Fast. The voice coil motor 107 has an angular resolution better than 1 microradian, which meets the accuracy requirements of the precise tracking stage. Its angle adjustment range reaches ±1.5°, providing sufficient beam scanning range for the acquisition and tracking process. The fast reflector on the voice coil motor 107 has an average reflectivity greater than 98% in the 1400nm to 1600nm operating wavelength range, ensuring efficient transmission in the communication optical band.

[0086] In one embodiment of the present invention, a beam splitter 108 is used to guide the light beam reflected by the fast-reflecting mirror to the tracking camera 1010 and the transmit / receive module 109, respectively. Within the communication optical wavelength range of 1550±50nm, the beam splitter 108 has a transmission-to-reflection ratio of 1:9, meaning that 10% of the light energy is transmitted to the tracking camera 1010 for beam monitoring, and 90% of the light energy is reflected to the transmit / receive module 109 for communication signal transmission and reception. The transmission wave aberration of the beam splitter 108 is better than 12.656nm, ensuring that the beam splitting process does not degrade the wavefront quality of the communication beam, thereby guaranteeing the accuracy of subsequent communication tests.

[0087] In one embodiment of the present invention, a tracking camera 1010 is used to receive the beam separated by a beam splitter 108 and to perform high-precision tracking and detection of the laser communication payload under test. The tracking camera 1010 includes four lenses. The optical system of the tracking camera 1010 has a focal length of 150mm, a light-transmitting aperture of 20mm, and an imaging spectral range of 1550nm±50nm, covering the communication optical band, and can directly monitor the communication beam. The first lens is an aperture stop. The overall surface accuracy of the four-lens combination system is better than 63.28nm, ensuring high-resolution imaging and accurate position detection of the returning beam, providing accurate position deviation information for subsequent fine tracking control.

[0088] In one embodiment of the present invention, the transmit / receive module 109 is used to transmit a test optical signal to the laser communication payload under test, and to receive a communication optical signal emitted by the laser communication payload under test. Figure 2 As shown, the transmit / receive module 109 includes a collimating coupling lens 1091, a first polarization-maintaining fiber 1092, a polarization-maintaining fiber circulator 1093, a first polarization-maintaining fiber U-shaped stage 1094, a filter 1095, a second polarization-maintaining fiber U-shaped stage 1096, and a second polarization-maintaining fiber 1097 arranged sequentially along the optical path.

[0089] The collimating coupling lens 1091 is located on the reflected optical path of the beam splitter 108. The collimating coupling lens 1091 can be a Thorlabs RC12APC-P01 lens, with an operating wavelength covering 1400nm to 1600nm, a focal length of 50.8mm, and an aperture of 25.4mm. The collimating coupling lens 1091 is used to collimate the test optical signal incident on the beam splitter 108, or to couple the communication optical signal returned from the laser communication payload under test and reflected by the beam splitter 108 into the first polarization-maintaining fiber 1092.

[0090] One end of the first polarization-maintaining fiber 1092 is connected to the collimating coupling lens 1091, and the other end is connected to the second port of the polarization-maintaining fiber circulator 1093. For example, the first polarization-maintaining fiber 1092 is a PC single-mode polarization-maintaining fiber. The end connected to the collimating coupling lens 1091 is a bare PC ceramic core (2.5 mm in diameter), and the end connected to the polarization-maintaining fiber circulator 1093 is an FC / APC fiber interface. The fiber material can be PM1550-XP, with a mode field diameter of 10.1 ± 0.4 μm at a wavelength of 1550 nm and a numerical aperture NA = 0.125, used to ensure that the polarization state remains stable during transmission.

[0091] The polarization-maintaining fiber circulator 1093 can be a Thorlabs CIR 1550PM-APC circulator, with an operating wavelength range of 1520nm to 1580nm and an isolation better than 50dB between the transmitting and receiving ports. The polarization-maintaining fiber circulator has three ports: the second port (part2) connects to the first polarization-maintaining fiber 1092, the third port (part3) connects to the first polarization-maintaining fiber U-shaped stage 1094, and the first port (part1) connects to the transmitting optical signal source, such as a laser.

[0092] The first polarization-maintaining fiber U-shaped stage 1094 is connected between the third port of the polarization-maintaining fiber circulator 1093 and the filter 1095, and the second polarization-maintaining fiber U-shaped stage 1096 is connected between the filter 1095 and the second polarization-maintaining fiber 1097. The first and second polarization-maintaining fiber U-shaped stages 1094 and 1096 have identical structures and are symmetrically arranged. They can use Thorlabs' FBC-1550PM-APC device, with a wavelength adaptation of 1550±20nm, an FC / APC interface, and a coupling loss of less than 0.9dB.

[0093] The filter 1095 is installed in the optical path between the first polarization-maintaining fiber U-shaped stage 1094 and the second polarization-maintaining fiber U-shaped stage 1096. The filter 1095 is a pluggable narrowband filter module, which can be replaced with filters of different center wavelengths according to testing requirements, such as narrowband filters with center wavelengths of 1540nm±3nm or 1563nm±3nm, to suppress background noise or select a specific communication channel and improve the received signal-to-noise ratio.

[0094] One end of the second polarization-maintaining fiber 1097 is connected to the second polarization-maintaining fiber U-shaped stage 1096, and the other end is used to connect to an external photodetector or demodulation device. The second polarization-maintaining fiber 1097 can be an FC / APC single-mode polarization-maintaining fiber, such as the Thorlabs P3-1550PM-FC-5 fiber, made of PM1550-XP material, with a mode field diameter of 10.1±0.4μm and a numerical aperture NA=0.125 at a wavelength of 1550nm. It is used to export the communication optical signal filtered by filter 1095.

[0095] Based on the laser communication ground testing device provided in any of the above embodiments, a second aspect of the present invention proposes a laser communication ground testing system, which includes an adjustment platform, a control unit, and the laser communication ground testing device provided in any of the above embodiments.

[0096] The laser communication ground test device is set on the adjustment platform. The control unit is electrically connected to the first alignment unit, the second alignment unit and the adjustment platform respectively. The control unit is used to control the movement of the adjustment platform according to the detection signal of the first alignment unit to achieve coarse tracking of the laser communication payload under test. The control unit is also used to control the voice coil motor 107 to drive the fast-reflecting mirror to move according to the position information measured by the tracking camera 1010 in the second alignment unit to achieve fine tracking of the laser communication payload under test.

[0097] Understandably, the laser communication ground testing device is fixedly set on the adjustment platform. The adjustment platform is used to move and adjust the spatial orientation of the entire device to adapt to laser communication payloads of different sizes, positions or orientations, and to meet the testing needs of multiple targets and multiple angles.

[0098] During the test, the receiving detector 106 in the first alignment unit first detects the beam emitted by the laser communication payload under test. If the receiving detector 106 cannot detect the laser communication payload under test, it means that the laser communication payload under test is not currently in the communication line-of-sight direction of the laser communication ground test device. At this time, the control unit controls the adjustment platform movement according to the feedback signal from the receiving detector 106, driving the entire device to perform a large-scale, low-precision azimuth scan and adjustment until the beam of the laser communication payload under test enters the field of view of the receiving detector 106, thereby completing coarse tracking.

[0099] Once coarse tracking is complete and the beam of the laser communication payload under test is introduced into the second alignment unit, the control unit calculates the deviation between the current spot position and the zero-position reference position based on the beam position information measured in real time by the tracking camera 1010 in the second alignment unit. Based on this deviation, the control unit drives the voice coil motor 107 to perform high-speed, high-precision micro-angle adjustments to finely correct the beam direction, ensuring the beam spot is always locked at the zero-position reference position of the tracking camera 1010. This establishes a stable fine tracking state, providing a guarantee for subsequent communication transmission and reception tests.

[0100] Based on the laser communication ground testing device provided in any of the above embodiments, embodiments of the present invention also propose a calibration method for the laser communication ground testing device, such as... Figure 3 As shown, the method includes the following steps:

[0101] Step 110: Place a reflective element in the incident light path of the beam-constricting optical unit.

[0102] Step 120: Calibrate the first alignment unit: Use a reflective element to reflect the beacon light emitted by the beacon light source 105 back to the receiving detector 106 to complete the optical axis calibration between the beacon light source 105 and the receiving detector 106 in the first alignment unit.

[0103] Step 130: Calibrate the second alignment unit: Use a reflective element to reflect the debugging light emitted by the transmitting / receiving module 109 back to the tracking camera 1010 to complete the optical axis calibration between the transmitting / receiving module 109 and the tracking camera 1010 in the second alignment unit.

[0104] Understandably, to ensure the accuracy of the test, the optical axes of each unit within the device are calibrated. Specifically, a reflective element, such as a corner cube prism, is placed at the incident light path of the beam-constricting optical unit (i.e., the external light port of the device); the corner cube prism can accurately return the incident light along its original direction. Using this reflective element, the optical axis calibration between the beacon light source 105 and the receiver detector 106, as well as the optical axis calibration between the transmitter / receiver module 109 and the tracking camera 1010, can be completed, thereby ensuring that the transmission and reception of the beacon light are coaxial, and that the transmission, reception, and tracking detection of the communication light are coaxial, thus ensuring the pointing consistency of the entire system.

[0105] Optionally, if the reflecting element is a cornerstone prism, step 120 may specifically include the following steps:

[0106] Step 121: Place the cornerstone prism in the incident light path of the beam-constricting optical unit.

[0107] Step 122: Turn on the beacon light source 105. The beacon light source 105 emits beacon light. The beacon light is expanded by the second dichroic mirror 104, the first dichroic mirror 103, and the beam-shrinking optical unit before being emitted to the corner cube prism.

[0108] Step 123: The beacon prism reflects the beacon light back, and after passing through the beam-shrinking optical unit, the first dichroic mirror 103 and the second dichroic mirror 104, it is incident on the receiving detector 106.

[0109] Step 124: Adjust the position of the receiver detector 106 until the converging light spot formed on the receiver detector 106 is located at the center of the target surface of the receiver detector 106, so as to complete the optical axis calibration between the beacon light source 105 and the receiver detector 106 in the first alignment unit.

[0110] In one specific embodiment, firstly, the off-axis primary mirror 101 and off-axis secondary mirror 102 are combined into a beam-constricting optical unit, and its optical axis zero position is confirmed using an interferometer. Then, a first dichroic mirror 103 is positioned at a 45° angle to the zero-position field of view to separate the visible light band (400nm~800nm) from the communication light band (1550nm±100nm). The first dichroic mirror 103 reflects the first beam of the visible light band and transmits the second beam of the communication light band. Next, a second dichroic mirror 104 is set up to separate the 671nm beacon light band from the 400nm to 600nm visible light band within the visible light band. The 671nm beacon light, after reflection by the second dichroic mirror 104, coincides with the optical axis of the beacon light source 105, while the 400nm to 600nm visible light, after passing through the second dichroic mirror 104, enters the visible light camera. After completing the above optical path setup, place the cornerstone prism at the center of the incident optical path of the off-axis primary mirror 101; turn on the beacon light source 105, and the beacon light emitted by the beacon light source 105 is reflected by the second dichroic mirror 104 and then incident on the first dichroic mirror 103. After being reflected by the first dichroic mirror 103 and expanded by the beam-shrinking optical unit, it is transmitted to the cornerstone prism. Utilizing the triple reflection characteristic of the cornerstone prism, the beam is accurately reflected back along the original path. The reflected beam is shrunken by the beam-shrinking optical unit, reflected by the first dichroic mirror 103, and then transmitted to the visible light camera by the second dichroic mirror 104. Finally, it is received by the visible light camera. By adjusting the position of the receiving detector 106 until the converging light spot formed on the receiving detector 106 is located at the center of the target surface of the receiving detector 106, the optical axis calibration between the beacon light source 105 and the receiving detector 106 in the first alignment unit is completed.

[0111] Understandably, after completing the optical axis calibration of the first alignment unit, for the rapid alignment of the laser communication payload under test, the beacon light source 105 is first turned on, emitting a beacon laser with a wavelength of 671nm. This beacon light is reflected by the second dichroic mirror 104 and then incident on the first dichroic mirror 103. After being reflected by the first dichroic mirror 103, it passes sequentially through the beam-shrinking optical unit composed of the off-axis secondary mirror 102 and the off-axis primary mirror 101 for beam expansion, finally exiting in the form of a large spot to illuminate the laser communication payload under test. Subsequently, a visible light camera receives the beam returned from the laser communication payload under test, completing the rapid capture and alignment of the output port of the laser communication payload under test, thereby achieving coarse alignment of the laser communication payload under test.

[0112] Optionally, if the reflecting element is a cornerstone prism, step 130 may specifically include the following steps:

[0113] Step 131: Adjust the positions of the transmitter / receiver module 109 and the beam splitter 108 so that the debugging light emitted by the transmitter / receiver module 109 enters the center of the fast reflector after passing through the beam splitter 108.

[0114] Step 132: Adjust the direction of the fast-reflecting mirror by using the voice coil motor 107 so that the optical axis of the adjustment light emitted from the fast-reflecting mirror and the beacon light emitted from the first dichroic mirror 103 coincides.

[0115] Step 133: Place the corner cube prism in the incident light path of the beam-shrinking optical unit, and adjust the light to be emitted to the corner cube prism after passing through the beam splitter 108, the fast reflection mirror, the first dichroic mirror 103, and the beam-shrinking optical unit for beam expansion.

[0116] Step 134: The corner prism reflects the adjustment light back, and after being condensed by the beam-shrinking optical unit, the first dichroic mirror 103, the fast-reflecting mirror, and the beam splitter 108, it is incident on the tracking camera 1010.

[0117] Step 135: Adjust the position of the tracking camera 1010 until the converging light spot formed by the tracking camera 1010 is located at the zero reference position of the tracking camera 1010, so as to complete the optical axis calibration between the transmitting / receiving module 109 and the tracking camera 1010 in the second alignment unit.

[0118] In one specific embodiment, after the optical axis calibration between the beacon light source 105 and the receiver detector 106 in the first alignment unit is completed, the optical axis calibration of the second alignment unit is performed. Specifically, the transmitter / receiver module 109 is placed in the corresponding position, and the reflection direction of the beam splitter 108 is adjusted so that the debugging light emitted by the transmitter / receiver module 109 is incident on the center of the fast reflector. The pointing angle of the fast reflector is adjusted by the voice coil motor 107 so that the optical axis of the debugging light emitted from the fast reflector coincides with the optical axis of the beacon light emitted from the first dichroic mirror 103, thereby achieving coaxial alignment of the first and second optical axes. The second optical axis continues to be transmitted through the first dichroic mirror 103 and enters the beam-shrinking optical unit composed of the off-axis secondary mirror 102 and the off-axis primary mirror 101, and is emitted outward after beam expansion and collimation. The corner cube prism is placed at the center of the light-emitting position of the off-axis primary mirror 101. The adjustment light emitted by the transmitting / receiving module 109 is reflected by the beam splitter 108, then by the fast-reflecting mirror, transmitted through the first dichroic mirror 103, and expanded by the beam-shrinking optical unit before exiting to the cornerstone prism. The triple reflection characteristic of the cornerstone prism is used to reflect the beam back along its original path. The returned adjustment light is then shrunken by the off-axis primary mirror 101 and the off-axis secondary mirror 102, then transmitted through the first dichroic mirror 103, and incident on the fast-reflecting mirror. After reflection by the fast-reflecting mirror, the adjustment light enters the beam splitter 108, and after transmission through the beam splitter 108, it finally enters the tracking camera 1010, forming a converging spot on the photosensitive surface of the tracking camera 1010. By fine-tuning the position of the tracking camera 1010, the converging spot is positioned at the zero-point reference position (target center) of the tracking camera 1010, thereby completing the optical axis calibration between the transmitting / receiving module 109 and the tracking camera 1010 in the second alignment unit.

[0119] Based on the laser communication ground testing device provided in any of the above embodiments, embodiments of the present invention also propose a laser communication ground testing method, such as... Figure 4 As shown, the method includes the following steps:

[0120] Step 10: Turn on the beacon light source 105. The beacon light source 105 emits beacon light. The beacon light is expanded by the second dichroic mirror 104, the first dichroic mirror 103, and the beam-shrinking optical unit before being emitted to the laser communication payload under test.

[0121] Step 20: The beam returned from the laser communication payload under test and emitted through the beam-shrinking optical unit, the first dichroic mirror 103 and the second dichroic mirror 104 is received by the receiving detector 106, and the output port characteristics of the laser communication payload under test are displayed in the field of view of the receiving detector 106.

[0122] Step 30: Obtain the current coordinate position of the beam returned from the laser communication payload under test by tracking camera 1010.

[0123] Step 40: Based on the deviation between the current coordinate position and the zero reference position, adjust the beam direction of the fast reflector using the voice coil motor 107 to lock the current coordinate position to the zero reference position.

[0124] Step 50: Perform a transmit / receive test with the laser communication payload under test through the transmit / receive module 109.

[0125] Understandably, the testing process of the laser communication ground test device is as follows: First, the beacon light source 105 is turned on. The beacon light emitted by the beacon light source 105 passes sequentially through the second dichroic mirror 104 and the first dichroic mirror 103 before reaching the beam-shrinking optical unit. After beam expansion, it exits as a large spot onto the laser communication payload under test, achieving pointing and coverage of the payload. Subsequently, the receiver detector 106 receives the beam returning from the laser communication payload under test and transmitted through the beam-shrinking optical unit, the first dichroic mirror 103, and the second dichroic mirror 104. At this time, the exit characteristics of the laser communication payload under test are displayed in the field of view of the receiver detector 106. The coarse alignment is completed. Then, the system switches to fine tracking mode. The tracking camera 1010 acquires the current coordinate position of the beam returned from the laser communication payload under test. The control unit drives the voice coil motor 107 to adjust the beam direction of the fast reflector based on the deviation between the current coordinate position and the zero reference position, forming a closed-loop control to keep the current coordinate position locked at the zero reference position, thereby achieving high-precision and stable tracking. Finally, after fine tracking is established and stabilized, the transmitter / receiver module 109 performs bidirectional communication optical signal transmission and reception tests with the laser communication payload under test to verify the communication performance of the payload.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ground-based testing device for laser communication, used to test a laser communication payload under test, characterized in that, The device includes: A beam-constricting optical unit is used to receive the laser beam emitted from the laser communication payload under test and to perform beam constriction. The first dichroic mirror is disposed on the beam output path of the beam-constricting optical unit and is used to separate the incident laser beam into a first beam and a second beam. The first alignment unit includes a second dichroic mirror, a beacon light source, and a receiver detector. The second dichroic mirror is disposed on the first beam output path of the first dichroic mirror. The beacon light source and the receiver detector are respectively located on two output beam paths of the second dichroic mirror. The beacon light emitted by the beacon light source is expanded by the second dichroic mirror, the first dichroic mirror, and the beam-shrinking optical unit before being emitted to cover the laser communication payload under test. The receiver detector is used to receive the laser beam emitted by the laser communication payload under test to achieve coarse alignment with the laser communication payload under test. The second alignment unit includes a voice coil motor, a beam splitter, a tracking camera, and a transmitter / receiver module. The voice coil motor is equipped with a fast-reflecting mirror, which is positioned on the second beam output path of the first dichroic mirror. The beam splitter is positioned on the beam reflection output path of the fast-reflecting mirror, used to separate the beam to the tracking camera and the transmitter / receiver module. The tracking camera is used to receive the separated beam to track and detect the laser communication payload under test. The transmitter / receiver module is used to transmit test light signals to the laser communication payload under test and / or receive communication light signals emitted by the laser communication payload under test.

2. The laser communication ground testing device according to claim 1, characterized in that, The beam-constricting optical unit includes an off-axis primary mirror and an off-axis secondary mirror disposed in the beam path of the off-axis primary mirror, wherein the first dichroic mirror is located in the beam path of the off-axis secondary mirror.

3. The laser communication ground testing device according to claim 1, characterized in that, The first dichroic mirror is used to reflect a first beam of light in the visible light band and transmit a second beam of light in the communication light band, or to transmit a first beam of light in the visible light band and reflect a second beam of light in the communication light band.

4. The laser communication ground testing device according to claim 3, characterized in that, The first dichroic mirror has a first film system that reflects in the visible light band and transmits in the communication light band. The first film system has a reflectivity of greater than or equal to 93% for the visible light band and a transmittance of greater than or equal to 92% for the communication light band.

5. The laser communication ground testing device according to any one of claims 1 to 4, characterized in that, The second dichroic mirror has a second film system, which has a reflectivity of 70% or greater for beacon light.

6. A ground-based laser communication testing system, characterized in that, Includes the laser communication ground testing apparatus as described in any one of claims 1 to 5, and: The adjustment platform is on which the laser communication ground testing device is mounted; The control unit is electrically connected to the first alignment unit, the second alignment unit, and the adjustment platform, respectively. The control unit is used to control the movement of the adjustment platform according to the detection signal of the first alignment unit to achieve coarse tracking of the laser communication payload under test. The control unit is also used to control the voice coil motor to drive the fast-reflecting mirror to move according to the position information measured by the tracking camera in the second alignment unit to achieve fine tracking of the laser communication payload under test.

7. A calibration method for a laser communication ground testing device according to any one of claims 1 to 5, characterized in that, include: A reflective element is placed in the incident optical path of the beam-contracting optical unit; The first alignment unit is calibrated by using the reflective element to reflect the beacon light emitted by the beacon light source back to the receiving detector, thereby completing the optical axis calibration between the beacon light source and the receiving detector in the first alignment unit. The second alignment unit is calibrated by using the reflective element to reflect the debugging light emitted by the transmitting / receiving module back to the tracking camera, thereby completing the optical axis calibration between the transmitting / receiving module and the tracking camera in the second alignment unit.

8. The calibration method for the laser communication ground test device according to claim 7, characterized in that, The reflective element is a cornerstone prism; The calibration of the first alignment unit includes: Place the cornerstone prism in the incident light path of the beam-constricting optical unit; The beacon light source is turned on, and the beacon light source emits beacon light. The beacon light is expanded by the second dichroic mirror, the first dichroic mirror, and the beam-shrinking optical unit before being emitted to the cornerstone prism. The cornerstone prism reflects the beacon light back, and after passing through the beam-shrinking optical unit, the first dichroic mirror, and the second dichroic mirror, it is incident on the receiving detector. By adjusting the position of the receiving detector until the converging light spot formed on the receiving detector is located at the center of the target surface of the receiving detector, the optical axis calibration between the beacon light source and the receiving detector in the first alignment unit is completed.

9. The calibration method for the laser communication ground test device according to claim 7, characterized in that, The reflective element is a cornerstone prism; The calibration of the second alignment unit includes: Adjust the positions of the transmitting / receiving module and the beam splitter so that the debugging light emitted by the transmitting / receiving module passes through the beam splitter and enters the center of the fast-reflecting mirror; The direction of the fast-reflecting mirror is adjusted by the voice coil motor so that the optical axis of the adjustment light emitted from the fast-reflecting mirror and the beacon light emitted from the first dichroic mirror coincides. The corner cube prism is placed in the incident light path of the beam-shrinking optical unit. The adjustment light is expanded by the beam splitter, the fast-reflecting mirror, the first dichroic mirror, and the beam-shrinking optical unit before exiting to the corner cube prism. The corner prism reflects the adjustment light back, and after being condensed by the beam-shrinking optical unit, the first dichroic mirror, the fast-reflecting mirror, and the beam splitter, it is incident on the tracking camera. By adjusting the position of the tracking camera until the converging light spot formed by the tracking camera is located at the zero reference position of the tracking camera, the optical axis calibration between the transmitting / receiving module and the tracking camera in the second alignment unit is completed.

10. A ground-based testing method for laser communication, characterized in that, Based on the laser communication ground testing device according to any one of claims 1 to 5, the method includes: The beacon light source is turned on, and the beacon light source emits beacon light. The beacon light is expanded by the second dichroic mirror, the first dichroic mirror, and the beam-shrinking optical unit before being emitted to the laser communication payload under test. The receiver detector receives the light beam returned from the laser communication payload under test and emitted through the beam-shrinking optical unit, the first dichroic mirror, and the second dichroic mirror, and the exit port characteristics of the laser communication payload under test are displayed in the field of view of the receiver detector. The tracking camera acquires the current coordinate position of the beam returned from the laser communication payload under test. Based on the deviation between the current coordinate position and the zero reference position, the beam direction of the fast-reflecting mirror is adjusted by the voice coil motor to lock the current coordinate position at the zero reference position; The transmitting / receiving module is used to perform a transmit / receive test with the laser communication payload under test.

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