Inter-satellite laser communication load on-orbit composite self-calibration device and method thereof

Abstract

The invention provides an inter-satellite laser communication load on-orbit composite self-calibration device and a method thereof, relates to the technical field of laser communication, and solves the problems of long calibration period, high system complexity, low reliability, overlong software processing time and the like in the prior art. In the device, signal laser is emitted by an emission light path assembly, sequentially passes through a dichroic mirror, an optical filter, a fast reflecting mirror and a coarse pointing mechanism and then enters a composite calibration mirror, and reflected laser formed by original path reflection sequentially passes through the coarse pointing mechanism, the fast reflecting mirror, the optical filter, the dichroic mirror and a spectroscope; at the spectroscope, the reflected laser is divided into two beams, one beam enters a communication receiving light path assembly, and an electric signal is output after photoelectric conversion; the other beam enters a camera light path assembly, a camera in the camera light path assembly completes the analysis of the mass center of the received light spot, and the optical axis deviation between the current emitting light path and the current receiving light path is judged; according to the invention, the load can be ensured to be aligned with the target more accurately, and meanwhile, the system complexity is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of laser communication technology, and in particular to an on-orbit composite self-calibration device and method for an inter-satellite laser communication payload. Background Art

[0002] As a typical application scenario in the field of space optical communication, intersatellite laser communication has attracted much attention because it is not affected by atmospheric turbulence. Compared with traditional microwave communication, laser communication has many advantages, including larger transmission capacity, stronger security and confidentiality, higher anti-interference ability, shorter communication delay and lower power consumption. These characteristics have made intersatellite laser communication a hot research area in recent years.

[0003] On-orbit self-calibration is one of the key technologies of laser communication payloads. Laser communication payloads are affected by the vibration and impact of rocket launch / payload separation, and the relative position of the optical lenses inside them may be displaced, which in turn changes the coaxiality of the receiving and transmitting optical paths, affecting the tracking effect and causing the payload sensitivity to decrease; the deformation of the optical lenses and structures will also cause the coarse pointing mechanism to slightly change its direction after vibration and impact, affecting the capture effect and increasing the time it takes to establish a link between payloads.

[0004] The existing coaxiality calibration technologies for the receiving and transmitting axes of intersatellite laser communication payloads include:

[0005] 1. The intersatellite laser communication payload is calibrated coaxially with the ground optical station by calculating the off-axis value between the transmit and receive optical axes. However, this method has a long calibration cycle and is difficult to quickly and accurately locate the off-axis value.

[0006] 2. On-orbit self-calibration of intersatellite laser communication payloads. Currently, the existing self-calibration methods are divided into: beacon light assisted calibration, that is, patent CN202011291747 (an on-orbit self-calibration device for space laser communication payloads and calibration method thereof) uses a movable shaft and beacon light in conjunction with a full-light reflection prism for calibration, but the patent method uses a conversion device, which will increase the complexity of the system and reduce reliability. Self-calibration without beacon light, that is, patent CN202210141497 (an on-orbit self-calibration device for satellite-borne laser communication equipment and calibration method thereof) uses an optical switch to switch the light transmission and receiving circuits, and realizes calibration through a corner cube prism; this method uses a large-aperture corner cube prism to achieve full-light reflection, and at the same time, additional calibration lasers, optical switches and other devices are added, which also increases the system redundancy. In addition, patent CN202310286368 (An on-orbit self-calibration device and method for satellite-borne laser communication payloads) uses a transmissive beam expansion system, which requires eliminating the influence of chromatic aberration of the wavelengths of the transmitting and receiving beams. At the same time, it requires scanning the corner cube prism / plane mirror to return to the position of the maximum power of the receiving detector for calibration, and the software processing time is too long.

[0007] In summary, under the premise of ensuring the self-calibration accuracy of the receiving and transmitting light axis of the intersatellite laser communication payload, how to develop an in-orbit self-calibration technology for the receiving and transmitting light axis of the intersatellite laser communication payload with high accuracy, low device complexity, simple software algorithm processing, stability and reliability has become the focus of technical personnel in this field. Summary of the invention

[0008] The purpose of the present invention is to solve the problems of long calibration cycle, high system complexity, low reliability and long software processing time in the existing on-orbit self-calibration technology of inter-satellite laser communication payloads, and therefore proposes an on-orbit composite self-calibration device and method for inter-satellite laser communication payloads. The present invention uses communication signal light without using beacon light or adding additional laser sources, and uses a plane mirror for secondary correction based on the self-calibration of a corner cube prism to eliminate the accuracy influence of the deviation of the pointing mechanism, thereby correcting the offset between the light-receiving and light-emitting axes.

[0009] The present invention adopts the following technical solutions to achieve the purpose:

[0010] In a first aspect, the present invention provides an on-orbit composite self-calibration device for an intersatellite laser communication payload, the device comprising a composite calibration mirror, a coarse pointing mechanism, a fast reflection mirror, a filter, a color separation mirror, a spectroscope, a transmitting optical path component, a communication receiving optical path component and a camera optical path component; a signal laser is emitted by the transmitting optical path component, passes through the color separation mirror, the filter, the fast reflection mirror and the coarse pointing mechanism in sequence, and then enters the composite calibration mirror, the composite calibration mirror reflects the signal laser along the original path, and the formed reflected laser passes through the coarse pointing mechanism, the fast reflection mirror, the filter, the color separation mirror and the spectroscope in sequence; at the spectroscope, the reflected laser is divided into two beams, one beam enters the communication receiving optical path component, and outputs an electrical signal after photoelectric conversion; the other beam enters the camera optical path component, and the camera therein performs the centroid analysis of the receiving light spot to determine the optical axis deviation between the current transmitting optical path and the receiving optical path.

[0011] Furthermore, the composite calibration mirror is installed on the intersatellite laser communication payload and is located outside the coarse pointing mechanism; the composite calibration mirror has a corner cube prism and a plane mirror, the signal laser transmitted by the coarse pointing mechanism is incident on the corner cube prism or the plane mirror, and the signal laser is not within the normal link building range of the intersatellite laser communication payload; the clear apertures of the corner cube prism and the plane mirror are both smaller than the emission aperture of the signal laser at the coarse pointing mechanism, and the corner cube prism and the plane mirror are respectively located on the path lines corresponding to the center of the signal laser emission position of the coarse pointing mechanism.

[0012] Furthermore, the coarse pointing mechanism includes a beam expander, a reflector and a swing mirror; after the signal laser is incident on the coarse pointing mechanism, it passes through the beam expander, the reflector and the swing mirror in sequence and then is emitted into the composite calibration mirror; the swing mirror is controlled by a two-position rotating mechanism, and under the control of the two-position rotating mechanism, the swing mirror makes the signal laser incident on the corner cone prism or the plane mirror in the composite calibration mirror.

[0013] In a second aspect, the present invention provides an on-orbit composite self-calibration method for an inter-satellite laser communication payload, the hardware basis of the method is the aforementioned device; the method comprises the following steps:

[0014] S1. Initialize the ground tracking points and ground self-calibration points, and record the pointing angle of the coarse pointing mechanism, the parameters of the transmitting optical path components and the camera;

[0015] S2. Perform pointing correction in the on-orbit calibration process and correct the coordinate system matrix of the inter-satellite laser communication payload;

[0016] S3. Perform the coaxiality correction of the transmitting and receiving in the on-orbit calibration process. According to the changes of the optical axes of the transmitting and receiving optical paths, determine the new tracking point coordinates and complete the coaxiality calibration of the transmitting and receiving optical axes.

[0017] In summary, due to the adoption of this technical solution, the beneficial effects of the present invention are as follows:

[0018] The present invention realizes the basic calibration of the coaxiality of transmission and reception by using the reflected light from the corner cube prism, and corrects the pointing accuracy of the coarse pointing mechanism by combining the reflected light from the plane mirror, thereby further improving the overall accuracy of the calibration based on the corner cube prism. This technology not only ensures that the payload can be more accurately aligned with the target, but also makes the subsequent communication link establishment more reliable.

[0019] The present invention can complete the calibration process without relying on the support of ground optical stations or other on-orbit intersatellite laser communication payloads, which greatly improves the independence and operational flexibility of the system, thereby avoiding the calibration delay problem caused by the unavailability of external equipment or coordination difficulties.

[0020] The present invention avoids the use of additional lasers or switching devices for calibration work, thereby simplifying the structure of the entire calibration system. This not only reduces hardware costs, but also reduces system power consumption and volume and weight requirements, which is conducive to the optimization of satellite payload configuration.

[0021] Since the calibration technology of the present invention does not require complicated external coordination and improves the calibration efficiency through improved method mechanisms, it can significantly reduce the time required for on-orbit alignment and capture of intersatellite laser communication payloads, which is crucial for quickly establishing stable and reliable intersatellite communication links. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the on-orbit composite self-calibration device for intersatellite laser communication payload of the present invention;

[0023] Figure 2 The figure briefly describes the process of the on-orbit composite self-calibration method of the intersatellite laser communication payload of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] like Figure 1 As shown, an on-orbit composite self-calibration device for intersatellite laser communication payload includes a composite calibration mirror, a coarse pointing mechanism, a fast reflection mirror, a filter, a color separation mirror, a spectroscope, a transmitting optical path component, a communication receiving optical path component and a camera optical path component; a signal laser is emitted by the transmitting optical path component, passes through the color separation mirror, the filter, the fast reflection mirror and the coarse pointing mechanism in sequence, and then enters the composite calibration mirror, the composite calibration mirror reflects the signal laser along the original path, and the formed reflected laser passes through the coarse pointing mechanism, the fast reflection mirror, the filter, the color separation mirror and the spectroscope in sequence; at the spectroscope, the reflected laser is divided into two beams, one beam enters the communication receiving optical path component, and outputs an electrical signal after photoelectric conversion; the other beam enters the camera optical path component, and the camera therein completes the centroid analysis of the receiving light spot, and determines the optical axis deviation between the current transmitting optical path and the receiving optical path.

[0028] In this embodiment, the composite calibration mirror is installed on the intersatellite laser communication payload and is located outside the coarse pointing mechanism; the composite calibration mirror has a corner cube prism and a plane mirror, and the signal laser transmitted by the coarse pointing mechanism is incident on the corner cube prism or the plane mirror, and the signal laser is not within the normal link building range of the intersatellite laser communication payload, so that the on-orbit composite calibration will not affect the normal operation of the payload. The light apertures of the corner cube prism and the plane mirror are both smaller than the emission aperture of the signal laser at the coarse pointing mechanism to reduce weight. At the same time, the corner cube prism and the plane mirror are respectively located on the path line corresponding to the center of the signal laser emission position of the coarse pointing mechanism, thereby ensuring that all the incident signal lasers are returned.

[0029] In this embodiment, the coarse pointing mechanism includes a beam expander, a reflector and a swing mirror; after the signal laser is incident on the coarse pointing mechanism, it passes through the beam expander, the reflector and the swing mirror in sequence and then exits into the composite calibration mirror; the swing mirror is controlled by a two-position rotating mechanism, and the swing mirror makes the signal laser incident on the corner cube prism or the plane mirror in the composite calibration mirror under the control of the two-position rotating mechanism. The beam expander used in this embodiment can be an off-axis reflective beam expander or a coaxial reflective beam expander.

[0030] In this embodiment, the emission optical path component includes a laser, an optical fiber and a collimator. The signal laser is excited by the laser, emitted after optical fiber coupling, and then emitted to free space through the collimator. The emission optical path component can be replaced by a laser that only includes a spatial light output function, and the collimator can also be replaced by a reflective coupling mirror. In specific applications, an advanced sight can be added for better use.

[0031] In this embodiment, the communication receiving optical path component includes a coupling mirror and a detector. A beam of reflected laser entering the communication receiving optical path component at the spectroscope is received by the detector after passing through the coupling mirror. The coupling methods of the detector include spatial coupling and optical fiber coupling.

[0032] In this embodiment, the camera optical path assembly includes a coupling mirror and a camera, and a beam of reflected laser light entering the camera optical path assembly at the beam splitter is received by the camera after passing through the coupling mirror in sequence. In specific applications, a beam splitter and a four-quadrant detector may be added to the camera optical path assembly, so that an additional reflected light beam is sent to the four-quadrant detector, so that the camera can achieve high-speed tracking effect.

[0033] Example 2

[0034] Based on Example 1, this example provides an on-orbit composite self-calibration method for inter-satellite laser communication payloads. The hardware of this method is based on the device in Example 1. Figure 2 The process is briefly described in the figure, and the steps of the method are summarized as follows:

[0035] S1. Initialize the ground tracking points and ground self-calibration points, and record the pointing angle of the coarse pointing mechanism, the parameters of the transmitting optical path components and the camera;

[0036] S2. Perform pointing correction in the on-orbit calibration process and correct the coordinate system matrix of the inter-satellite laser communication payload;

[0037] S3. Perform the coaxiality correction of the transmitting and receiving in the on-orbit calibration process. According to the changes of the optical axes of the transmitting and receiving optical paths, determine the new tracking point coordinates and complete the coaxiality calibration of the transmitting and receiving optical axes.

[0038] In step S1, when initializing the ground tracking point, the calibrated collimator is used to obtain the initial tracking point of the intersatellite laser communication payload, and the corresponding camera coordinate is marked as Q0 (x0, y0), which represents the center direction of the payload receiving optical path;

[0039] When initializing the ground self-calibration point, the intersatellite laser communication payload is powered on, and the coarse pointing mechanism is controlled to point to the corner cube prism and the plane mirror in the composite calibration mirror respectively. After the transmission process of the signal laser and the reflected laser, the reflection point Q1 (x1, y1) of the corner cube prism and the reflection point Q2 (x2, y2) of the plane mirror are generated at the camera; the parameters of the transmitting optical path component and the camera are adjusted to make the camera fit the centroid position of the receiving light spot, and then the composite calibration mirror is further fine-tuned to make the reflection point Q1 coincide with the reflection point Q2, that is, Q1 = Q2 (x1 = x2, y1 = y2); the pointing angle of the coarse pointing mechanism, the parameters of the transmitting optical path component and the camera are recorded at this time.

[0040] In step S2, the intersatellite laser communication payload in the orbital state is powered on, and the transmitting optical path components, camera and coarse pointing mechanism are set according to the parameters obtained in step S1 to obtain the plane mirror self-calibration point Q2′(x2′,y2′) in the orbital state; under the influence of the mechanical and thermal factors in the launch-to-orbit process, the plane mirror self-calibration point Q2′ no longer coincides with the reflection point Q2, and the change δQ′ between the two is used as the coordinate system change of the coarse pointing mechanism, that is, δQ′=Q2-Q2′; the change δQ′ is substituted into the coordinate system matrix of the laser in the transmitting optical path component to realize the correction of the coordinate system matrix of the intersatellite laser communication payload. The correction in this step can eliminate the influence of the change of the absolute pointing accuracy of the coarse pointing mechanism on the self-calibration, and can also reduce the initial uncertainty area of ​​the capture.

[0041] In step S3, the on-orbit intersatellite laser communication payload is powered on, and according to the corrected coordinate system matrix of the intersatellite laser communication payload, the transmitting optical path components, the camera and the coarse pointing mechanism are set again according to the parameters obtained in step S1 to obtain a new on-orbit plane mirror self-calibration point Q1′(x1′, y1′); under the influence of the mechanical and thermal factors of the launch-to-orbit process, the coaxiality of the receiving and transmitting optical axis and the relative position of the coarse pointing mechanism pointing to the plane mirror are changed, so that x1=x1′, and the change δQ of the two is used as the optical axis change of the transmitting optical path and the receiving optical path, that is, δQ=Q1-Q1′; therefore, the new tracking point coordinates of the intersatellite laser communication payload are Q0′=Q0+δQ, completing the on-orbit coaxiality calibration of the receiving and transmitting optical axis.

[0042] In summary, the on-orbit composite self-calibration device and method for intersatellite laser communication payload provided by the present invention effectively reduce the complexity and cost of the system without sacrificing the calibration accuracy, and greatly shorten the calibration time, demonstrating its significant superiority in practical applications.

Claims

1. An on-orbit composite self-calibration device for intersatellite laser communication payload, characterized in that: The device comprises a composite calibration mirror, a coarse pointing mechanism, a fast reflection mirror, a filter, a color separation mirror, a spectroscope, a transmitting optical path component, a communication receiving optical path component and a camera optical path component; a signal laser is emitted from the transmitting optical path component, passes through the color separation mirror, the filter, the fast reflection mirror and the coarse pointing mechanism in sequence, and then enters the composite calibration mirror; the composite calibration mirror reflects the signal laser along the original path, and the formed reflected laser passes through the coarse pointing mechanism, the fast reflection mirror, the filter, the color separation mirror and the spectroscope in sequence; at the spectroscope, the reflected laser is divided into two beams, one beam enters the communication receiving optical path component, and outputs an electrical signal after photoelectric conversion; the other beam enters the camera optical path component, and the camera therein completes the centroid analysis of the receiving light spot, and determines the optical axis deviation between the current transmitting optical path and the receiving optical path.

2. The on-orbit composite self-calibration device for intersatellite laser communication payload according to claim 1 is characterized in that: The composite calibration mirror is installed on the intersatellite laser communication payload and is located outside the coarse pointing mechanism; the composite calibration mirror has a corner cube prism and a plane mirror, the signal laser transmitted by the coarse pointing mechanism is incident on the corner cube prism or the plane mirror, and the signal laser is not within the normal link building range of the intersatellite laser communication payload; the clear apertures of the corner cube prism and the plane mirror are both smaller than the emission aperture of the signal laser at the coarse pointing mechanism, and the corner cube prism and the plane mirror are respectively located on the path lines corresponding to the center of the signal laser emission position of the coarse pointing mechanism.

3. The on-orbit composite self-calibration device for inter-satellite laser communication payload according to claim 2 is characterized in that: The coarse pointing mechanism includes a beam expander, a reflector and a swing mirror; after the signal laser is incident on the coarse pointing mechanism, it passes through the beam expander, the reflector and the swing mirror in sequence and then is emitted into the composite calibration mirror; the swing mirror is controlled by a two-position rotating mechanism, and under the control of the two-position rotating mechanism, the swing mirror makes the signal laser incident on the corner cone prism or the plane mirror in the composite calibration mirror.

4. The on-orbit composite self-calibration device for intersatellite laser communication payload according to claim 1 is characterized in that: The emission optical path components include a laser, an optical fiber and a collimator. The signal laser is generated by the laser excitation, emitted after being coupled by the optical fiber, and then emitted into the free space through the collimator.

5. The on-orbit composite self-calibration device for inter-satellite laser communication payload according to claim 1 is characterized in that: The communication receiving optical path component includes a coupling mirror and a detector. A beam of reflected laser entering the communication receiving optical path component at the beam splitter passes through the coupling mirror and is received by the detector. The coupling modes of the detector include space coupling and optical fiber coupling.

6. The on-orbit composite self-calibration device for intersatellite laser communication payload according to claim 1 is characterized in that: The camera optical path component includes a coupling mirror and a camera. A beam of reflected laser light entering the camera optical path component at the beam splitter passes through the coupling mirror in sequence and is received by the camera.

7. An on-orbit composite self-calibration method for intersatellite laser communication payload, characterized in that: The hardware basis of the method is the device according to claim 1; the method comprises the following steps: S1. Initialize the ground tracking points and ground self-calibration points, and record the pointing angle of the coarse pointing mechanism, the parameters of the transmitting optical path components and the camera; S2. Perform pointing correction in the on-orbit calibration process and correct the coordinate system matrix of the inter-satellite laser communication payload; S3. Perform the coaxiality correction of the transmitting and receiving in the on-orbit calibration process. According to the changes of the optical axes of the transmitting and receiving optical paths, determine the new tracking point coordinates and complete the coaxiality calibration of the transmitting and receiving optical axes.

8. The on-orbit composite self-calibration method for inter-satellite laser communication payload according to claim 7 is characterized in that: In step S1, when initializing the ground tracking point, the calibrated collimator is used to obtain the initial tracking point of the intersatellite laser communication payload, and the corresponding camera coordinate is marked as Q0 (x0, y0), which represents the center direction of the payload receiving optical path; When initializing the ground self-calibration point, the intersatellite laser communication payload is powered on, and the coarse pointing mechanism is controlled to point to the corner cube prism and the plane mirror in the composite calibration mirror respectively. After the transmission process of the signal laser and the reflected laser, the reflection point Q1 (x1, y1) of the corner cube prism and the reflection point Q2 (x2, y2) of the plane mirror are generated at the camera; the parameters of the transmitting optical path component and the camera are adjusted to make the camera fit the centroid position of the receiving light spot, and then the composite calibration mirror is further fine-tuned to make the reflection point Q1 coincide with the reflection point Q2, that is, Q1 = Q2 (x1 = x2, y1 = y2); the pointing angle of the coarse pointing mechanism, the parameters of the transmitting optical path component and the camera are recorded at this time.

9. The on-orbit composite self-calibration method for inter-satellite laser communication payload according to claim 8 is characterized in that: In step S2, the on-orbit intersatellite laser communication payload is powered on, and the transmitting optical path components, camera and coarse pointing mechanism are set according to the parameters obtained in step S1 to obtain the on-orbit plane mirror self-calibration point Q2′(x2′, y2′); under the influence of the mechanical and thermal factors in the launch-in-orbit process, the plane mirror self-calibration point Q2′ no longer coincides with the reflection point Q2, and the change δQ′ between the two is used as the coordinate system change of the coarse pointing mechanism, that is, δQ′=Q2-Q2′; the change δQ′ is substituted into the coordinate system matrix of the laser in the transmitting optical path component to realize the correction of the coordinate system matrix of the intersatellite laser communication payload.

10. The on-orbit composite self-calibration method for inter-satellite laser communication payload according to claim 9 is characterized in that: In step S3, the on-orbit intersatellite laser communication payload is powered on, and according to the corrected coordinate system matrix of the intersatellite laser communication payload, the transmitting optical path components, the camera and the coarse pointing mechanism are set again according to the parameters obtained in step S1 to obtain a new on-orbit plane mirror self-calibration point Q1′(x1′, y1′); under the influence of the mechanical and thermal factors of the launch-to-orbit process, the coaxiality of the receiving and transmitting optical axis and the relative position of the coarse pointing mechanism pointing to the plane mirror are changed, so that x1=x1′, and the change δQ of the two is used as the optical axis change of the transmitting optical path and the receiving optical path, that is, δQ=Q1-Q1′; therefore, the new tracking point coordinates of the intersatellite laser communication payload are Q0′=Q0+δQ, completing the on-orbit coaxiality calibration of the receiving and transmitting optical axis.

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