Laser communication device for rapid link establishment and networking and satellite internet constellation

Abstract

The invention provides a laser communication device for rapid link establishment and networking and a satellite internet constellation. The device utilizes the wavelength division multiplexing unit and the pre-aiming unit to realize beam combination of receiving and transmitting optical path signals so as to improve the coaxiality of receiving and transmitting branches; an optical fiber displacement device arranged on the transmitting-receiving lens is used for adjusting the relative position of the beam combining optical fiber and the focal point of the transmitting-receiving lens, and continuous beam changing of a transmitted light path signal within the divergence angle range of 55-1000 microrad is achieved; and a position sensing unit is matched to focus a receiving light path signal, so that a 0.2-1-degree receiving light path continuous field of view is realized. Through 10000 times of offset error estimation simulation, the coverage rate of an uncertain area to a target light spot reaches 99.32%, and about 1mrad beam change can be realized, so that minute-level capture efficiency is realized under the condition of the continuous field of view.

Description

Technical Field

[0001] This application relates to the field of satellite laser communication technology, and more specifically to a laser communication device and satellite internet constellation for rapid link establishment and networking. Background Technology

[0002] Current satellite laser communication terminals need to be equipped with star sensors to obtain the real-time attitude of the satellite, so as to calibrate and guide the laser transmission direction based on the satellite's current roll angle, pitch angle, yaw angle and other data, which is therefore costly.

[0003] Furthermore, existing satellite laser communication terminals all require the use of small-beam divergence for data transmission. Their positioning process typically involves a small field-of-view camera, using a field-of-view scan to cover uncertain areas for beam acquisition. This aiming and acquisition process is time-consuming, with link establishment generally taking more than a month.

[0004] For communication optical paths requiring relay equipment, the transmitting and receiving modules of the relay unit need to be equipped with beam combiners, resulting in a complex, large-sized, and time-consuming relay system. Furthermore, since the transmitting and receiving units cannot be reused, they often require independent design and assembly. However, during communication, a high degree of coaxiality is required between the transmitting and receiving branches, which poses significant challenges to ground assembly and adjustment. Even after accurate ground assembly and adjustment, the laser communication terminal's transmission into orbit is still affected by the space environment, and vibrations can cause misalignment of the transmitting and receiving branches within the satellite. Therefore, the satellite still needs recalibration after entering orbit, requiring the configuration of self-calibration components. This calibration process is complex and time-consuming, severely impacting the efficiency of link establishment and networking between satellite internet constellations.

[0005] Even after satellites have been focused and established in orbit, they are still affected by the space environment, causing their transmission and reception branches to change slowly and irregularly. This results in coaxiality misalignment between the transmission and reception branches, making it impossible to maintain stable communication for extended periods. Summary of the Invention

[0006] This application addresses the shortcomings of existing technologies by providing a laser communication device and satellite internet constellation for rapid link establishment and networking. This application utilizes a fiber optic displacement device on the transceiver lens to precisely calibrate the position of the combined fiber, combined with the focusing function of the position sensing unit. This, along with a beam-expanding antenna, enables continuous beam modulation of the transmitted beam from 55μrad to 1000μrad. Thus, during the pointing calibration phase, the transmitted beam is modulated to 500μrad–1000μrad, covering uncertain areas in a single scan and reducing the scan time to less than one minute. During the link establishment and communication phase, the beam is modulated to 55μrad–100μrad, achieving rapid link establishment and networking. The specific technical solution adopted in this application is as follows.

[0007] First, to achieve the above objectives, a laser communication device for rapid link establishment and networking is proposed, comprising: a wavelength division multiplexing (WDM) unit, which connects both the receiving and transmitting optical fibers for beam combining the received and transmitted optical signals; a transceiver lens, connected to the WDM unit, having an optical fiber displacement device connecting the beam combining fiber for adjusting the position of the beam combining fiber relative to the focal point of the transceiver lens; a pre-aiming unit, which pre-adjusts the optical path direction based on the transmitted optical signal; a position sensing unit, which focuses the received optical signal and adjusts the optical path direction of a precision tracking fast-reflecting mirror based on the position of the focused spot; a precision tracking fast-reflecting mirror, which adjusts the aiming angle in response to the spot coordinates captured by the position sensing unit; a folding mirror, which performs coarse tracking of the beam direction of the optical signal; and a beam expander antenna, used for transmitting and receiving laser communication optical signals into space.

[0008] The laser communication device for rapid link establishment and networking as described above, wherein the fiber displacement device includes: an axial displacement device that adjusts the relative position of the bundled fiber and the transceiver lens along the optical axis of the transceiver lens; which, in conjunction with the beam expander antenna, realizes continuous beam variation of the transmitted optical path signal within the divergence angle range of 55μrad to 1000μrad.

[0009] The laser communication device for rapid link establishment and networking as described above, wherein the displacement device includes: a linear motor, one side of which is set on the base plate on which the lens barrel of the transceiver lens is mounted, and the other side is fixedly connected to the optical fiber. The linear motor moves back and forth relative to the transceiver lens to adjust the distance between the two to change the divergence angle of the laser in the optical fiber reaching the position of the lens barrel.

[0010] The laser communication device for rapid link establishment and networking as described above, wherein the position sensing unit includes: a beam splitter, used to reflect the light beam between the pre-aiming unit and the precision tracking mirror to the camera according to a preset ratio; a focusing lens group, which is disposed between the beam splitter and the camera, used to focus the light beam reflected to the camera, and in conjunction with the beam expander antenna, to achieve a continuous field of view of the receiving optical path of 0.2° to 1°; the camera is used to receive the light beam after focusing by the focusing lens group, detect the light spot coordinates in real time, and adjust the tracking angle of the folding mirror and the precision tracking mirror in real time based on the light spot coordinates.

[0011] The laser communication device for rapid link establishment and networking as described above, wherein the focusing lens group includes: a fixed lens group, which receives the light beam reflected from the beam splitter to the camera, respectively disposed at both ends of the camera lens barrel; and a focusing lens group, which is disposed between the fixed lens group and the camera and is connected to a focusing drive device for reciprocating along the optical axis of the fixed lens group to focus the light beam onto the camera to detect the coordinates of the light spot.

[0012] The laser communication device for rapid link establishment and networking as described above, wherein the pre-aiming unit comprises: a main path isosceles right-angle prism, through which the received optical path signal is transmitted and reflected by the two right-angle faces; a rhombic offset prism, which is disposed on the right-angle face of the main path isosceles right-angle prism near the transceiver lens, and reflects the transmitted optical path signal to the pre-aiming mirror on the opposite side of this face; a combining isosceles right-angle prism, whose hypotenuse is disposed on the right-angle face of the main path isosceles right-angle prism near the fine-tracking fast-reflecting mirror, and reflects the transmitted optical path signal reflected by the pre-aiming mirror to the combining isosceles right-angle prism in the opposite direction to the received optical path signal to the fine-tracking fast-reflecting mirror; the pre-aiming mirror is disposed between the 45° rhombic offset prism and the combining isosceles right-angle prism, and reflects the transmitted optical path signal to the right-angle face of the combining isosceles right-angle prism at an incident angle of approximately 45°.

[0013] In any of the laser communication devices described above for rapid link establishment and networking, the cross-section of the rhombic offset prism parallel to the optical axis is a parallelogram, with the acute angle of the side closest to the main path isosceles right-angled prism set at 45° and the right angle of the side closest to the main path isosceles right-angled prism set at 135°. On both sides of the 45° angle of the rhombic offset prism, a dichroic film is coated on the side closest to the main path isosceles right-angled prism, and a light-receiving path signal is coated on the side perpendicular to the hypotenuse of the main path isosceles right-angled prism. The anti-reflection coating of the main path isosceles right-angle prism is coated with a reflective coating on the opposite side of the right-angle face of the main path isosceles right-angle prism; the combining isosceles right-angle prism is coated with an anti-reflection coating for emitting light path signals on its side parallel to the hypotenuse of the main path isosceles right-angle prism, a dichroic coating on its hypotenuse, and an anti-reflection coating for receiving light path signals on its side perpendicular to the hypotenuse of the main path isosceles right-angle prism; the main path isosceles right-angle prism is coated with matte black paint on its hypotenuse; the dichroic coating reflects the emitted light path signals and transmits the received light path signals.

[0014] In any of the laser communication devices described above for rapid link establishment and networking, the pre-aiming reflector has a fast-reaction drive unit, which is used to adjust the rotation angle of the pre-aiming reflector according to the inter-satellite relative position relationship, and superimpose a lead angle on the beam direction of the emitted optical path signal to compensate for the time delay deviation in the transmission process of inter-satellite laser communication light waves.

[0015] Meanwhile, to achieve the above objectives, this application also provides a satellite internet constellation, which includes several satellites, the optical heads of which are equipped with laser communication devices for rapid link establishment and networking as described above; between two communicating satellites, laser communication light waves of different wavelengths are used as transceiver beams in different transmission directions.

[0016] Beneficial effects This application provides a rapid link establishment and networking laser communication device and satellite internet constellation. The device utilizes a wavelength division multiplexing (WDM) unit and a pre-aiming unit to combine the transmit and receive optical signals, improving the coaxiality between the transmit and receive branches in the system. It uses a fiber displacement device configured on the transceiver lens to adjust the position of the combined fiber relative to the focal point of the transceiver lens, and works with a beam expander antenna to achieve continuous beam variation of the transmit optical signal within a divergence angle range of 55 μrad to 1000 μrad. A position sensing unit focuses the receive optical signal, achieving a continuous field of view of 0.2° to 1°. Therefore, the system of this application can achieve 99.32% coverage of the target light spot in uncertain areas in 10,000 bias error estimation simulations. Combined with the transmit beam, it can achieve approximately 1 mrad beam variation, thereby achieving minute-level acquisition efficiency under the continuous field of view conditions. The laser communication device provided in this application enables the transmit beam to quickly achieve bias error coverage of uncertain areas, and achieves minute-level laser communication light wave acquisition under continuous field of view conditions of 0.2° to 1°.

[0017] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present application and form part of the specification. Together with the embodiments of the present application, they serve to explain the present application but do not constitute a limitation thereof. In the drawings: Figure 1 This is a system block diagram of the internal structure of a satellite in the satellite internet constellation of this application; Figure 2 yes Figure 1 A schematic diagram of the principle of the laser communication device used in the optical head of the satellite for rapid link establishment and networking; Figure 3 This is a schematic diagram of the transceiver lens in the laser communication device for rapid link establishment and networking as described in this application; Figure 4 This is a schematic diagram of the position sensing unit in the laser communication device for rapid link establishment and networking of this application; Figure 5 This describes the distribution of the target in the uncertain acquisition area of ​​the laser communication device for rapid link establishment and networking described in this application; Figure 6 This is a principle model of the beam-switching mechanism in the laser communication device for rapid link establishment and networking in this application; Figure 7 This is a schematic diagram of the displacement device used in the apparatus of this application. Detailed Implementation

[0019] To make the objectives and technical solutions of the embodiments of this application clearer, the technical solutions of the embodiments of this application 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 application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0020] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0021] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0022] The terms "receive" and "transmit" as used in this application refer to the direction in which laser communication light waves are received from space, and the direction in which laser communication light waves are transmitted from the system into space, rather than a specific limitation on the device mechanism of this application.

[0023] This application provides a satellite internet constellation comprising several satellites capable of communicating with each other. (See reference...) Figure 1 As shown, each satellite includes: an optical head for exchanging optical path signals, used to establish a space optical link and expand, transmit, and receive optical signals; an electrical control box for adjusting corresponding components in the optical head, to power and control the optical head and communication unit, and to enable interaction between the laser communication system status and the satellite platform; a communication unit for parsing data in the optical path signals and modulating the data to be transmitted by the satellite; and a satellite platform for providing remote control, detection, and service data to each device, enabling the communication unit to receive and process service data from the satellite platform, and to enable interaction between the communication unit status and the satellite platform. In this constellation, the two communicating satellites use different wavelengths of laser communication light waves as transmit and receive beams in different transmission directions. For example, the optical path signal sent by satellite A to satellite B is set at the first wavelength, while it uses the second wavelength to receive optical path signals from other satellites; satellite B receives the optical path signal from satellite A at the first wavelength, but transmits the optical path signal outward at the second wavelength. In this way, the signal transmission and reception of each satellite can be carried out simultaneously at different wavelengths, multiplexing the same optical system.

[0024] Traditional laser communication equipment typically sets the camera field of view to 0.2° and the divergence angle to 55 μurad. During on-orbit testing, vibrations from rocket launches often cause deviations in the laser communication equipment. While these deviations are usually no greater than 1 degree, the 55 μurad divergence angle, combined with parameters such as the laser equipment's overlap capability and dwell time, means that achieving full coverage scanning to overcome these deviations can take up to ten hours. However, if the divergence angle during the scanning process can be increased, full coverage scanning of the space beam receiving direction can be achieved much faster, significantly reducing link establishment time.

[0025] This application differs from traditional satellite laser communication technology by configuring the optical heads of the aforementioned satellites as follows: Figure 2 The structure shown, by focusing the divergence angle to 1 mrad, improves the equipment coverage efficiency by approximately 160%, effectively shortening the scanning time required for link establishment, enabling rapid link establishment and networking between satellites, and improving the efficiency of laser communication. The laser communication system provided in this application includes: a coarse pointing / tracking unit (elevation and azimuth two-axis rotation mechanism), a fine tracking unit (fine tracking fast-reflection mirror), a pre-aiming unit, a transmitting / receiving unit, a beam splitting assembly, and a position sensing unit.

[0026] The coarse pointing / tracking unit, which performs the initial pointing and coarse tracking functions of the laser communication system, includes: A folding mirror is used for coarse tracking of the beam direction of an optical signal. A beam expander antenna is used to transmit and receive optical signals for laser communication in space.

[0027] The precision tracking unit used to achieve accurate aiming in inter-satellite laser communication systems includes: The position sensing unit focuses the received optical path signal and adjusts the optical path direction of the precision tracking mirror according to the position of the focused spot. The precision tracking and quick-reflecting scope adjusts the aiming angle in response to the coordinates of the light spot captured by the position sensing unit.

[0028] The pre-aiming unit, used to calculate the pre-aiming angle based on satellite position and attitude data and to pre-point the transmitted beam, employs a scheme using a combined prism to accelerate the reflection mirror, including: The pre-aiming unit pre-adjusts the direction of the optical path based on the transmitted optical path signal.

[0029] The optical head of this application combines the receiving lens and the transmitting lens into a single lens; the transmitting fiber and the receiving fiber are combined into a single bundled fiber after being bundled by a wavelength division multiplexing (WDM) unit. Its structure includes: a wavelength division multiplexing (WDM) unit, which simultaneously connects the receiving fiber and the transmitting fiber, used to bundle the received and transmitted optical signals to achieve wavelength division multiplexing; The transceiver lens is connected to a wavelength division multiplexing unit and has an optical fiber displacement device for connecting the bundled optical fiber after the wavelength division multiplexing unit has bundled the fibers. The optical fiber displacement device is used to adjust the relative position of the bundled optical fiber with respect to the focal point of the transceiver lens.

[0030] This optical head achieves high-precision displacement adjustment of the bundled fiber along the optical axis through a fiber displacement device. The adjustment accuracy of the fiber displacement device is better than 1μm, and the movement range is 2mm. It achieves continuous adjustment of the beam divergence angle through fiber displacement. Combined with a beam expander antenna, the emitted beam can achieve continuous beam variation from 55μrad to 1000μrad. During the pointing calibration stage, the beam can be varied to 500μrad to 1000μrad, covering an uncertain area in a single scan, with a required scan time of less than 1 minute. During the link establishment communication stage, the beam can be varied to 55μrad to 100μrad.

[0031] Specific reference Figure 3 as well as Figure 7 To achieve the above effects, the fiber optic displacement device of this application adjusts the relative position of the bundled fiber and the transceiver lens along the optical axis of the transceiver lens; its specific structure, in conjunction with the beam expander antenna, enables continuous beam shifting of the transmitted optical signal within the divergence angle range of 55μrad to 1000μrad, includes: A linear motor is mounted on the base plate on which the lens barrel of the transceiver lens is installed on one side, and is fixedly connected to the optical fiber on the other side. The linear motor moves back and forth relative to the transceiver lens to adjust the distance between the two and change the divergence angle of the laser in the optical fiber when it reaches the position of the lens barrel.

[0032] In order to increase the field of view of the camera in the receiving optical path and facilitate accurate focusing of the diverging beam onto the camera to form an accurate spot position for precise positioning, this application refers to... Figure 4 The structure shown configures the focusing lens group to include components respectively located at both ends of the camera lens barrel: A fixed lens assembly that receives the light beam reflected from the beam splitter to the camera; The focusing lens group is positioned between the fixed lens group and the camera, and is connected to a focusing drive device. It is used to reciprocate along the optical axis of the fixed lens group to focus the light beam onto the camera to detect the coordinates of the light spot.

[0033] Therefore, this application, through a focusing lens group in conjunction with a fixed lens group and a beam expander antenna, can achieve a continuous field of view of 0.2° to 1°. During the pointing calibration phase, the field of view is adjusted to 1° using a fiber optic displacement device and a camera focusing lens group, allowing spot capture without field-of-view scanning in a staring mode. Conversely, the satellite in this application can adjust to a 0.2° field of view during the link establishment phase, and combined with detector windowing technology, achieve high-precision spot position detection, providing a closed-loop signal for high-precision dynamic real-time link establishment.

[0034] To accurately obtain the position of the light spot for precise orientation, the satellite in this application may have its position sensing unit configured as follows: A beam splitter is used to reflect the light beam between the pre-aiming unit and the precision tracking mirror to the camera according to a preset ratio. The focusing lens assembly, which is positioned between the beam splitter and the camera, is used to focus the light beam reflected to the camera. Together with the beam expander antenna, it achieves a continuous field of view for the receiving optical path of 0.2° to 1°. The camera is used to receive the light beam after focusing by the focusing lens group, detect the light spot coordinates in real time, and adjust the tracking angle of the folding mirror and the fine-tracking mirror in real time based on the light spot coordinates.

[0035] To achieve synchronous processing of the received and transmitted optical signals, this application may refer to Figure 2 The pre-aiming unit between the transceiver lens and the beam splitter is configured as a single unit consisting of a main path isosceles right-angle prism, a rhombic offset prism, and a combining path isosceles right-angle prism. These prisms form different refraction paths for the incident and transmitted light paths, respectively, which, in conjunction with the reflection from the pre-aiming mirror, allow for adjustment of the pre-aiming angle of the transmitted light path. Its specific structural design is as follows: The main path is an isosceles right-angled prism, which receives optical signals through its two right-angled faces and emits optical signals by reflecting them from its two right-angled faces. The rhomboid offset prism, which is an oblique prism, is set on the right-angled face of the main path isosceles right-angle prism near the transceiver lens. On the opposite side of this face, the transmitted light path signal is reflected to the pre-aiming mirror. The combined isosceles right-angle prism has its hypotenuse set on the right-angle face of the main isosceles right-angle prism near the precision tracking mirror. On this face, the emitted light path signal reflected by the pre-aiming mirror to the combined isosceles right-angle prism is reflected to the precision tracking mirror in the opposite direction to the received light path signal. The material of the aforementioned prism 3 can all be fused silica. The short side of the rhombic offset prism is the same length as the right-angled side of the merging isosceles right-angled prism; the long side of the rhombic offset prism is the same length as the right-angled side of the main isosceles right-angled prism; and the right-angled side of the main isosceles right-angled prism is the same length as the hypotenuse of the merging isosceles right-angled prism. The acute angle of the rhombic offset prism, the acute angle of the merging isosceles right-angled prism, and the acute angle of the main isosceles right-angled prism are all 45°.

[0036] The prisms are fixedly connected by adhesive bonding. On one side of the prisms, a pre-aiming reflector is placed between the 45° rhombic offset prism and the combining isosceles right-angle prism. This reflector reflects the emitted light path signal to the right-angle face of the combining isosceles right-angle prism at an incident angle of approximately 45°.

[0037] In this combination prism, the cross section of the rhomboid offset prism parallel to the optical axis can be specifically set as a parallelogram, with the acute angle of the side of the rhomboid offset prism closest to the main path isosceles right angle prism set at 45°, and the right angle of the side of the rhomboid offset prism closest to the main path isosceles right angle prism set at 135°. On both sides of the 45° angle of the rhombic offset prism, a dichroic film is coated on the side of the prism closest to the main path isosceles right angle prism, and an anti-reflection film for receiving and transmitting light path signals is coated on the side of the prism perpendicular to the hypotenuse of the main path isosceles right angle prism. The combined isosceles right-angle prism has an anti-reflection coating for emitting light path signals on its side parallel to the hypotenuse of the main isosceles right-angle prism, a dichroic coating on its hypotenuse, and an anti-reflection coating for receiving light path signals on its side perpendicular to the hypotenuse of the main isosceles right-angle prism. The pre-aiming mirror on one side of the prism is connected to the corresponding fast-reaction drive unit, which can be referenced. Figure 6 The loop shown is controlled in a closed loop. Based on the position of the light spot, the reflection angle of the fast reflector is changed by the driving unit, so that it can adjust the rotation angle of the pre-aiming reflector according to the relative position of the satellites. The lead angle is superimposed on the beam direction of the transmitted optical signal to compensate for the time delay deviation in the transmission process of inter-satellite laser communication light waves.

[0038] Therefore, the left vertical face of the rhombic offset prism in the combined prism is coated with anti-reflection films for both the receiving and transmitting wavelength bands, ensuring a transmittance of >99% for the communication wavelength; the lower face of the rhombic offset prism, close to the inclined surface of the main isosceles right-angle prism, is coated with a dichroic film to ensure that this plane has a transmittance of >99% for the receiving wavelength and a reflectivity of >99% for the transmitting wavelength; the upper face of the rhombic offset prism, away from the inclined surface of the main isosceles right-angle prism, is coated with a reflective film to ensure that this plane has a reflectivity of >99% for the transmitting wavelength; the right face of the rhombic offset prism, close to the reflective surface of the main isosceles right-angle prism, is coated with a reflective film to ensure that this plane has a reflectivity of >99% for the transmitting wavelength; the right face of the rhombic offset prism is close to the reflective surface of the main isosceles right-angle prism. The vertical surface of the reflecting mirror is coated with an anti-reflection film to ensure that the transmittance of this plane to the emitted wavelength is >99%. The right-angled surface of the combining isosceles right-angle prism, close to the reflecting mirror, is also coated with an anti-reflection film to ensure that the transmittance of this plane to the emitted wavelength is >99%. The inclined surface of the combining isosceles right-angle prism, which is attached to the main isosceles right-angle prism on the left side, is coated with a dichroic film to ensure that the transmittance of this plane to the received wavelength is >99% and the reflectance to the emitted wavelength is >99%. The inclined surface of the bottom of the main isosceles right-angle prism is coated with matte black paint as an absorption film, so that the absorption rate of the communication band is >95%. This combined structure can provide the emitted light path with a zigzag light path that enters horizontally from the rhombic offset prism, turns upward, is reflected by the fast-reflecting mirror to the combining isosceles right-angle prism, and finally exits horizontally to the right. At the same time, it can provide the incident light path with an incident light path that goes straight from the combining isosceles right-angle prism, through the main isosceles right-angle prism, and then directly horizontally to the transceiver lens via the rhombic offset prism. With the two optical paths having the same entry and exit positions, the rotation angle of the pre-aiming reflector can be adjusted by changing the reflection angle of the fast reflector in the transmitting optical path according to the relative position relationship between the satellites. This allows for the superposition of a lead angle on the beam direction of the transmitting optical path signal, thereby compensating for the time delay deviation in the transmission of inter-satellite laser communication light waves and enabling tracking with the opposite satellite.

[0039] By estimating the bias error in the uncertain region, it can be seen that the error before calibration after orbit insertion is generally on the order of mrad. Therefore, an uncertain region is established for the error value before calibration. (Refer to...) Figure 5 The simulation results establishing the relationship between the uncertain region and the coverage rate show that, in 10,000 simulations, the coverage rate of the uncertain region on the target spot is approximately 99.32%. In other words, under the parameters shown in Table 1, this application can achieve a beam variation of 1000 μrad (1 mrad) by adjusting the emitted beam, and the emitted beam can quickly cover the uncertain region, i.e., the offset error.

[0040] Table 1. Error Items for Offset Angle Calculation Specifically, when calculating the theoretical time for successful spot capture, this application requires the following relationship to be satisfied: Where the scanning step size is The half-width of the divergence angle is The maximum amplitude of micro-vibration on the satellite platform is , Therefore, overlap factor It must satisfy the following relationship: Number of rows and columns of the scan matrix and fine scanning area They satisfy the following relationship: Scan dwell time Finally, the scan time of the row-by-row spiral scan algorithm is: Therefore, it can be concluded that under the conditions that the transmitted beam can achieve continuous beam variation of 55μrad to 1000μrad and the received field of view can achieve continuous field of view of 0.2° to 1°, successful acquisition within minutes can be achieved.

[0041] Considering that mechanical vibrations during satellite launch can cause movement of the optical fiber relative to the transceiver lens and relative movement between other optical components, in order to overcome the impact of such structural offsets on the satellite optical communication signal acquisition process, this application can use the farthest movement distance in the coarse positioning stage. That is, the optical fiber displacement device is adjusted along the optical axis of the transceiver lens to the position where the relative distance between the bundled optical fiber and the transceiver lens is the farthest. At this time, the light spot can be magnified to 1000 μurad to ensure that the target can be illuminated through the maximum divergence angle, and coarse positioning can be achieved quickly. Correspondingly, in the subsequent fine positioning stage, the fiber displacement device can be adjusted along the optical axis of the transceiver lens to a position where the relative distance between the bundled fiber and the transceiver lens is minimized. Thus, by using the shortest possible movement distance, the light spot for real-time tracking and interaction after positioning is maintained at 55 μm, ensuring that the maximum energy of the laser signal can be effectively received by the communicating party during communication, facilitating normal system interaction and communication.

[0042] In summary, this application combines the receiving and transmitting lenses into a single lens; merges the receiving and transmitting optical fibers into a single fiber after passing through a wavelength division multiplexing (WDM) unit; and uses an optical head composed of a coarse pointing unit, a fine tracking unit, a beam splitter, a position sensing unit, and a transceiver unit. By using an optical fiber displacement device with an accuracy better than 1 μm and a movement range of 2 mm, combined with a beam expander antenna, the transmitted beam can achieve continuous beam scaling from 55 μrad to 1000 μrad. During the pointing calibration stage, the beam is scaled to 500 μrad to 1000 μrad, and during the link establishment communication stage, it is scaled to 55 μrad to 100 μrad.

[0043] The focusing lens group used in this application, in conjunction with the fixed lens group and the beam expander antenna, can achieve a continuous field of view of 0.2° to 1°. During the pointing calibration phase, the field of view can be adjusted to 1°, allowing the staring party to capture the light spot without field scanning. During the link establishment phase, the field of view is adjusted to 0.2°, which, combined with detector windowing technology, enables high-precision light spot position detection, providing a closed-loop signal for high-precision dynamic real-time link establishment. Therefore, this application can achieve beam capture within minutes, enabling rapid link establishment. The overall optical head design of this application is more streamlined, with the transceiver lens sharing a single lens, thus simplifying assembly and adjustment and effectively reducing costs.

[0044] Furthermore, this application can combine the receiving and transmitting beams using a prism, fixing the angle between the transmitting and receiving beams for easy assembly and adjustment. After the satellite provided by this application is launched into orbit, due to the multiplexing of the receiving and transmitting optical paths, inconsistencies in transmit and receive coaxiality are less likely to occur, eliminating the need for on-orbit calibration of transmit and receive coaxiality, enabling rapid link establishment, improving the reliability and availability of the laser communication system, and facilitating large-scale promotion and application.

[0045] The above are merely embodiments of this application, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A rapid chain-building, networking laser communication device, characterized in that, The application relates to a laser communication device, which comprises the following parts: a wavelength division multiplexing unit, which is connected with a receiving optical fiber and a transmitting optical fiber simultaneously, and is used for combining the receiving and transmitting optical path signals; a receiving and transmitting lens, which is connected with the wavelength division multiplexing unit, and has an optical fiber displacement device connected with the combined optical fiber, and is used for adjusting the position of the combined optical fiber relative to the focus of the receiving and transmitting lens; a pre-aiming unit, which is used for pre-adjusting the direction of the optical path according to the transmitting optical path signal; a position sensing unit, which is used for focusing the receiving optical path signal, and adjusting the direction of the optical path according to the position of the light spot formed by focusing; a fast tracking mirror, which is used for adjusting the aiming angle in response to the light spot coordinates captured by the position sensing unit; a turning mirror, which is used for roughly tracking the beam direction of the optical path signal; an extended beam antenna, which is used for transmitting and receiving the optical path signal of laser communication in space.

2. The quick link-up and networking laser communication device of claim 1, wherein, The optical fiber displacement device adjusts the relative position of the combined optical fiber and the receiving and transmitting lens along the optical axis of the receiving and transmitting lens. The extended beam antenna is used for realizing the continuous beam change of the transmitting optical path signal in the divergence angle interval of 55 mu rad to 1000 mu rad.

3. The quick link-up and networking laser communication device of claim 2, wherein, The displacement device comprises: a linear motor, which is arranged on one side of a bottom plate on which a lens barrel of the receiving and transmitting lens is installed, and is fixedly connected with an optical fiber on the other side, and is used for moving back and forth relative to the receiving and transmitting lens to adjust the distance between the two to change the divergence angle of laser in the optical fiber to the position of the lens barrel.

4. The quick link-up and networking laser communication device of claim 1, wherein, The position sensing unit comprises: a beam splitter, which is used for reflecting the light beam between the pre-aiming unit and the fast tracking mirror to a camera according to a preset ratio; a focusing lens group, which is arranged between the beam splitter and the camera, and is used for focusing the light beam reflected to the camera, and realizes the continuous field of view of 0.2 DEG to 1 DEG of the receiving optical path in cooperation with the extended beam antenna; The camera is used for receiving the light beam focused by the focusing lens group, and detecting the light spot coordinates in real time, so as to adjust the tracking angle of the turning mirror and the fast tracking mirror in real time based on the light spot coordinates.

5. The quick link-up and networking laser communication device of claim 4, wherein, The focusing lens group comprises: a fixed lens group, which receives the light beam reflected to the camera by the beam splitter; a focusing lens group, which is arranged between the fixed lens group and the camera, and is connected with a focusing driving device, and is used for reciprocating along the optical axis of the fixed lens group to focus the light beam on the camera to detect the light spot coordinates.

6. The quick link-up and networking laser communication device of claim 1, wherein, The pre-aiming unit comprises: a main path isosceles right prism, which is used for transmitting the receiving optical path signal through two right angle faces, and reflecting the transmitting optical path signal; a rhombic offset prism, which is arranged on the right angle face of the main path isosceles right prism close to the receiving and transmitting lens, and reflects the transmitting optical path signal to the pre-aiming mirror on the opposite side of the face; a combined path isosceles right prism, which is arranged on the right angle face of the main path isosceles right prism close to the fast tracking mirror, and reflects the transmitting optical path signal reflected by the pre-aiming mirror to the fast tracking mirror in the direction opposite to the receiving optical path signal; The pre-aiming mirror is arranged between the 45 DEG rhombic offset prism and the combined path isosceles right prism, and reflects the transmitting optical path signal to the right angle face of the combined path isosceles right prism at an incident angle close to 45 DEG.

7. The quick link-up and networking laser communication device according to claim 6, wherein, The rhombic offset prism has a parallelogram cross section parallel to the optical axis direction, and the corner close to the acute angle side of the main path isosceles right prism is set to 45°, and the corner close to the right angle side of the main path isosceles right prism is set to 135°. The 45° corner of the rhombic offset prism is coated with a dichroic film on the side close to the side of the main path isosceles right prism, and a transmittance film for transmitting and receiving light path signals is coated on the side perpendicular to the hypotenuse surface of the main path isosceles right prism; The rhombic offset prism is also coated with a reflective film on the side opposite to the right angle surface of the main path isosceles right prism; The main path isosceles right prism is coated with a transmittance film for transmitting light path signals on the side parallel to the hypotenuse surface of the main path isosceles right prism, a dichroic film on the hypotenuse surface, and a transmittance film for transmitting and receiving light path signals on the side perpendicular to the hypotenuse surface of the main path isosceles right prism; The main path isosceles right prism is coated with a light extinction black paint on the hypotenuse surface; The dichroic film reflects the emitted light path signals and transmits the received light path signals.

8. The quick link-up and networking laser communication device of claim 6, wherein, The pre-aiming mirror has a fast reflection driving unit for adjusting the rotation angle of the pre-aiming mirror according to the relative position relationship between the satellites, and superimposing a lead angle on the direction of the emitted light path signal beam to offset the time delay deviation in the process of transmitting the laser communication light wave.

9. A satellite internet constellation, characterized in that, The system includes a plurality of satellites, and the optical head of each satellite is provided with a fast chain building and networking laser communication device as claimed in any one of claims 1-8; and different wavelengths of laser communication light waves are used as the transmitting and receiving beams in different transmission directions between two satellites in communication with each other.

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