A Miniaturized Space-Ground Laser Communication Terminal Based on Single-Photon Detection Technology

Abstract

The present invention discloses a miniaturized space-ground laser communication terminal based on single-photon detection technology, belonging to the technical field of optical communication devices. It consists of 7 optical paths, namely the observation and reception optical path A, the signal transmission optical path B, the near-infrared beacon reception optical path C, the short-wave infrared beacon reception optical path D, the single-photon signal reception optical path E, the single-photon beacon reception optical path F, and the beacon transmission optical path G. These optical paths jointly complete the transceiver and detection of beacon light / signal light of single-photon / non-single-photon respectively. This terminal can be used for space-ground laser communication. Compared with traditional space-ground laser communication terminals, the antenna aperture is reduced to 20-30% of the original, the volume is only 20% of that of traditional space-ground terminals, and the weight can be reduced by 80%. At the same time, it can not only complete space-ground transmission, but also be compatible with the ground-to-ground point-to-point laser communication ability, greatly expanding the use range of laser communication ground stations, and can be widely used in air-ground, space-ground, deep space, and ground-to-ground point-to-point laser communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical communication equipment, and particularly relates to a miniaturized space-ground laser communication terminal based on single-photon detection technology. Background Art

[0002] Compared with the existing microwave communication technology, satellite laser communication technology has significant advantages such as high data rate, strong anti-interference ability, and good confidentiality, and is an effective supplementary technical means for future satellite communication. At present, a number of satellite optical communication in-orbit tests have been carried out at home and abroad, and military and commercial space applications are gradually being developed.

[0003] Compared with the traditional microwave communication system, the laser communication system uses the optical wave band as the information carrier (carrier 10~400THz), has an extremely high communication bandwidth, and at the same time has the outstanding advantages of light weight, small volume, and low power consumption.

[0004] The laser communication antenna is responsible for completing the whole satellite of the transmitted signal / beacon light, beam divergence angle compression, and pointing transmission; at the same time, it completes the collection, beam splitting, and focusing of the received signal / beacon light on the corresponding detector. Traditional laser communication systems use devices such as PIN, PD, and APD, and the photosensitive material is InGaAs or GaAs, and its sensitivity is generally 40~42dBm@10Gbpa; while the spot position detector is a CCD or CMOS device, and the photosensitive surface material is InGaAs or Si material, and its sensitivity is -60~65dBm. The sensitivity is relatively low, the aperture of the terminal optical antenna needs to be relatively large (500mm~1600mm), and the volume (6~20m³), weight (2~10t), and power consumption of the terminal are all large, so that the traditional laser communication ground station needs to be built on a fixed house or a large-sized heavy vehicle, which severely restricts the application range of the laser communication ground terminal. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a miniaturized space-ground laser communication terminal based on single-photon detection technology, which uses a single-photon positioning detector and a single-photon communication detector as the position and communication detectors of laser communication, greatly improving the sensitivity of the system detector (-75~-80dBm), and at the same time realizing small-aperture reception (150~200mm), significantly reducing the system weight (from 2~8t to 400kg), reducing the system cost, and at the same time with the reduction of weight, the terminal can be carried and transported by a small vehicle, not only can realize space-ground communication transmission, but also with the reduction of volume, it can realize high-speed laser transmission between ground points-to-point between fixed points and between fixed points and moving points, greatly expanding the application range of the laser communication ground terminal.

[0006] The above object is achieved by the following technical solutions:

[0007] A miniaturized space - to - ground laser communication terminal based on single - photon detection technology, comprising the following optical components:

[0008] Main telescope, Mirror 1, Filter 1, Coarse beacon receiving lens group, Coarse beacon detector, Mirror 2, Mirror 5, Compensation mirror group, Fine tracking mirror 1, Mirror 3, Bidirectional corner - cube prism group, Mirror 4, Mirror 6, Light trap, Beam splitter 3, Signal emission mirror group, Signal light source, Filter 2, Fine beacon 1 receiving lens group, Fine beacon 1 detector, Fine tracking mirror 2, Beam splitter 1, Filter 3, Fine beacon 2 receiving lens group, Fine beacon 2 detector, Optical booster, Beam splitter 2, Single - photon beacon receiving filter, Single - photon beacon receiving lens group, Single - photon positioning detector, Single - photon signal receiving filter, Single - photon signal receiving lens group, Single - photon communication detector, Beacon / signal laser, Beacon / signal transmitting antenna;

[0009] The above - mentioned optical components constitute the observation and reception optical path A, signal emission optical path B, near - infrared beacon reception optical path C, short - wave infrared beacon reception optical path D, single - photon signal reception optical path E, single - photon beacon reception optical path F, and beacon emission optical path G, where:

[0010] The observation and reception optical path A is composed of a main telescope, Mirror 1, Filter 1, a coarse beacon receiving lens group, and a coarse beacon detector. After the external received beam is collected and focused by the main telescope, it is incident on Mirror 1 for reflection, then incident on Filter 1 and the coarse beacon receiving lens group, and finally incident on the coarse beacon detector to complete the beacon light reception and positioning work. This optical path is used to measure the incident coarse beacon light;

[0011] The signal emission optical path B is composed of a main telescope, Mirror 2, Mirror 5, a compensation mirror group, Fine tracking mirror 1, Mirror 3, Mirror 4, Mirror 6, Beam splitter 3, a signal emission mirror group, and a signal light source. First, the signal light source sends a signal light of a specified wavelength, which is shaped by the signal emission mirror group, then transmitted through Beam splitter 3, and then reflected by Mirror 6, Mirror 4, Mirror 3, and Fine tracking mirror 1. After passing through the compensation mirror group, Mirror 5, and Mirror 2 again, it is shaped and focused by the main telescope and then emitted to the target;

[0012] The near - infrared beacon reception optical path C is composed of a main telescope, Mirror 2, Mirror 5, a compensation mirror group, Fine tracking mirror 1, Mirror 3, Mirror 4, Mirror 6, Beam splitter 3, Filter 2, a fine beacon 1 receiving lens group, and a fine beacon 1 detector. The external beacon light is received and focused by the main telescope, and then incident on Filter 2 and the fine beacon 1 receiving lens group through Mirror 5, Fine tracking mirror 1, Mirror 3, Mirror 4, Mirror 6, and Beam splitter 3, and finally forms an image on the fine beacon 1 detector. This optical path uses the beacon light spot information on the fine beacon 1 detector to achieve closed - loop tracking of the fine tracking mirror 1;

[0013] The short-wave infrared beacon receiving optical path D consists of the main telescope, mirror two, mirror five, compensation mirror group, fine tracking mirror one, mirror three, mirror four, mirror six, fine tracking mirror two, beam splitter one, filter three, fine beacon two receiving mirror group, and fine beacon two detector. After the external short-wave infrared beacon light is received and reduced in beam by the main telescope, it passes through mirror five, the compensation mirror group, fine tracking mirror one, mirror three, mirror four, mirror six, fine tracking mirror two, and beam splitter one and is incident on filter three and the fine beacon two receiving mirror group, and finally forms an image on the fine beacon two detector. This optical path uses the beacon light spot information on the fine beacon two detector to achieve closed-loop tracking of the fine tracking mirror two;

[0014] The single-photon signal receiving optical path E consists of the main telescope, mirror two, mirror five, compensation mirror group, fine tracking mirror one, mirror three, mirror four, mirror six, fine tracking mirror two, beam splitter one, optical booster, beam splitter two, single-photon signal receiving filter, single-photon signal receiving mirror group, and single-photon communication detector. After the external communication light is received and reduced in beam by the main telescope, it passes through mirror five, the compensation mirror group, fine tracking mirror one, mirror three, mirror four, mirror six, fine tracking mirror two, and beam splitter one and is incident on the optical booster, then after being reflected by beam splitter two, it is incident on the single-photon signal receiving filter and the single-photon signal receiving mirror group, and finally is focused and incident on the single-photon communication detector. The single-photon communication detector is used to complete the communication signal reception of the received signal light;

[0015] The single-photon beacon receiving optical path F consists of the main telescope, mirror two, mirror five, compensation mirror group, fine tracking mirror one, mirror three, mirror four, mirror six, fine tracking mirror two, beam splitter one, optical booster, beam splitter two, single-photon beacon receiving filter, single-photon beacon receiving mirror group, and single-photon positioning detector. After the external communication light is received and reduced in beam by the main telescope, it passes through mirror five, the compensation mirror group, fine tracking mirror one, mirror three, mirror four, mirror six, fine tracking mirror two, and beam splitter one and is incident on the optical booster, and after being reflected by beam splitter two, it is incident on the single-photon beacon receiving filter and the single-photon beacon receiving mirror group, and finally forms an image on the single-photon positioning detector. This optical path uses the single-photon positioning information on the single-photon positioning detector for closed-loop tracking of the fine tracking mirror two;

[0016] Beacon emission optical path: It consists of a beacon / signal laser and a beacon / signal emission antenna. The beacon light with a suitable wavelength is emitted by the beacon laser and is shaped and the beam divergence angle is compressed by the beacon / signal emission antenna, and is sent while following the two-dimensional turntable of the theodolite to point to the target.

[0017] Furthermore, the main telescope, the first reflector, the first filter, the coarse beacon receiving lens group, the coarse beacon detector, the second reflector, the fifth reflector, the compensation lens group, the first fine tracking mirror, the third reflector, the bidirectional corner cube prism group, the fourth reflector, the beacon / signal laser, and the beacon / signal transmitting antenna are placed on the two-dimensional theodolite turntable; the target tracking of the two-dimensional theodolite turntable is controlled by the feedback of the spot position on the coarse beacon detector.

[0018] Furthermore, the main telescope adopts a Cassegrain telescope.

[0019] Furthermore, the bidirectional corner cube prism group is inserted into the optical path through a servo mechanism, and the aperture of the bidirectional corner cube prism group should be greater than 2 inches.

[0020] Furthermore, an adaptive optical component is added between the fourth reflector and the sixth reflector, and the adaptive optical component is 32 - 64 units.

[0021] Furthermore, the splitting ratio of the first beam splitter needs to be divided according to the sensitivity characteristics of the second fine beacon detector, the single - photon communication detector, and the single - photon positioning detector, that is, the splitting ratio of the first beam splitter , where is the sensitivity of the second fine beacon detector, with the unit of dBm; is the sensitivity of the single - photon positioning detector, with the unit of dBm; is the sensitivity of the single - photon communication detector, with the unit of dBm.

[0022] Beneficial effects:

[0023] 1. Compared with the traditional Coudé optical path antenna, the space - to - ground laser communication terminal of the present invention designs a large - field - of - view beacon receiving optical path that does not pass through the Coudé optical path arm for receiving the large - field - of - view beacon of the target; the present invention adopts a two - stage fast steering mirror design of the first fine tracking mirror and the second fine tracking mirror. Among them, the first - stage fast steering mirror is controlled by the beacon detector, and at the same time, it compensates for the axis error of the turntable optical path. The second - stage fast steering mirror is controlled by the second fine beacon detector or the single - photon positioning detector to compensate for the coarse tracking of the turntable and the tracking residual error of the first - stage fast steering mirror; the single - photon positioning detector includes but is not limited to a single - photon quadrant detector, and can also be other multi - pixel single - photon positioning detectors.

[0024] 2. The space - to - ground laser communication terminal of the present invention designs a bidirectional corner cube prism group as a self - inspection mechanism. The bidirectional corner cube prism group is inserted into the optical path through a servo mechanism, so that the system can detect the coaxiality of the signal transmitting optical path, the near - infrared beacon receiving optical path, the short - wave infrared beacon receiving optical path, the single - photon signal receiving optical path, the single - photon beacon receiving optical path, etc. without relying on an external light source, which facilitates the use of the system.

[0025] 3. To address the problem that the ultrasensitive detection of single-photon detectors is extremely sensitive to noise, the present invention designs an optical trap to effectively eliminate the optical signals in the emission optical path and avoid false alarms of single-photon detectors.

[0026] 4. The present invention designs an optical booster to isolate the rear optical path of the terminal from the single-photon detector and simultaneously provides degrees of freedom in the azimuth and altitude directions. Description of the Drawings

[0027] Figure 1 is the schematic diagram of the overall optical path of the present invention;

[0028] Figure 2 is the schematic diagram of the observation and reception optical path A of the present invention;

[0029] Figure 3 is the schematic diagram of the signal emission optical path B of the present invention;

[0030] Figure 4 is the schematic diagram of the near-infrared beacon reception optical path C of the present invention;

[0031] Figure 5 is the schematic diagram of the short-wave infrared beacon reception optical path D of the present invention;

[0032] Figure 6 is the schematic diagram of the single-photon signal reception optical path E of the present invention;

[0033] Figure 7 is the schematic diagram of the single-photon beacon reception optical path F of the present invention;

[0034] Figure 8 is the schematic diagram of the beacon emission optical path G of the present invention;

[0035] Description of each component in the figure: 1. Main telescope; 2. First mirror; 3. First filter; 4. Coarse beacon reception lens group; 5. Coarse beacon detector; 6. Second mirror; 7. Fifth mirror; 8. Compensation mirror group; 9. First fine tracking mirror; 10. Third mirror; 11. Theodolite two-dimensional turntable; 12. Bidirectional corner reflector prism group; 13. Fourth mirror; 14. Sixth mirror; 15. Optical trap; 16. Third beam splitter; 17. Signal emission mirror group; 18. Signal light source; 19. Second filter; 20. First fine beacon reception lens group; 21. First fine beacon detector; 22. Second fine tracking mirror; 23. First beam splitter; 24. Third filter; 25. Second fine beacon reception lens group; 26. Second fine beacon detector; 27. Optical booster; 28. Second beam splitter; 29. Single-photon beacon reception filter; 30. Single-photon beacon reception lens group; 31. Single-photon positioning detector; 32. Single-photon signal reception filter; 33. Single-photon signal reception lens group; 34. Single-photon communication detector; 35. Beacon / signal laser; 36. Beacon / signal transmitting antenna. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] As shown in the Figure 1 accompanying drawings, the miniaturized space-ground laser communication terminal based on single-photon detection technology in this embodiment includes the following optical elements:

[0038] Main telescope 1, first mirror 2, first filter 3, coarse beacon receiving lens group 4, coarse beacon detector 5, second mirror 6, fifth mirror 7, compensation lens group 8, first fine tracking mirror 9, third mirror 10, bidirectional corner cube prism group 12, fourth mirror 13, sixth mirror 14, light trap 15, third beam splitter 16, signal emission mirror group 17, signal light source 18, second filter 19, first fine beacon receiving lens group 20, first fine beacon detector 21, second fine tracking mirror 22, first beam splitter 23, third filter 24, second fine beacon receiving lens group 25, second fine beacon detector 26, optical booster 27, second beam splitter 28, single-photon beacon receiving filter 29, single-photon beacon receiving lens group 30, single-photon positioning detector 31, single-photon signal receiving filter 32, single-photon signal receiving lens group 33, single-photon communication detector 34, beacon / signal laser 35, beacon / signal transmitting antenna 36;

[0039] The above optical elements constitute 7 optical paths, namely observation and receiving optical path A, signal emission optical path B, near-infrared beacon receiving optical path C, short-wave infrared beacon receiving optical path D, single-photon signal receiving optical path E, single-photon beacon receiving optical path F, and beacon emission optical path G. These optical paths jointly complete the transceiver and detection of single-photon / non-single-photon beacon light / signal light, and jointly form a small laser communication terminal based on single-photon detection. This terminal can be used for space-ground laser communication. Compared with the traditional space-ground laser communication terminal, the antenna aperture is reduced to 20-30% of the original, the volume is only 20% of the traditional space-ground terminal, the weight can be reduced by 80%, and it is only 200-300 kg; at the same time, the miniaturization brings convenience for transportation and use. It can not only complete space-ground transmission, but also be compatible with the ground-to-ground point-to-point laser communication ability, quickly realize the conversion of space-ground and ground-ground communication, and can greatly expand the use range of the laser communication ground station. It can be widely used in air-ground, space-ground, deep space, and ground-to-ground point-to-point laser communication.

[0040] As Figure 2As shown in the figure, the observation and reception optical path A in this embodiment is composed of a main telescope 1, a first reflector 2, a first filter 3, a coarse beacon receiving lens group 4, and a coarse beacon detector 5. After the external received light beam is collected and reduced in beam diameter by the main telescope 1, it is reflected by the first reflector 2, then enters the first filter 3 and the coarse beacon receiving lens group 4, and finally enters the coarse beacon detector 5 to complete the beacon light reception and positioning work. This optical path is used to measure the incident coarse beacon light; the target tracking of the theodolite two-dimensional turntable 11 is controlled by the position feedback of the light spot on the coarse beacon detector 5.

[0041] As Figure 3 shown in the figure, the signal transmission optical path B in this embodiment is composed of a main telescope 1, a second reflector 6, a fifth reflector 7, a compensation lens group 8, a first fine tracking mirror 9, a third reflector 10, a fourth reflector 13, a sixth reflector 14, a third beam splitter 16, a signal transmission mirror group 17, and a signal light source 18. First, the signal light source 18 sends a signal light of a specified wavelength, and after being shaped by the signal transmission mirror group 17, it is transmitted through the third beam splitter 16, and then after being reflected by the sixth reflector 14, the fourth reflector 13, the third reflector 10, and the first fine tracking mirror 9, it passes through the compensation lens group 8 and the fifth reflector 7 and the second reflector 6 again, and then is shaped and reduced in beam diameter by the main telescope 1 and then emitted to the target.

[0042] As Figure 4 shown in the figure, the near-infrared beacon reception optical path C in this embodiment is composed of a main telescope 1, a second reflector 6, a fifth reflector 7, a compensation lens group 8, a first fine tracking mirror 9, a third reflector 10, a fourth reflector 13, a sixth reflector 14, a third beam splitter 16, a second filter 19, a first fine beacon receiving lens group 20, and a first fine beacon detector 21. After the external beacon light is received and reduced in beam diameter by the main telescope 1, it passes through the fifth reflector 7, the first fine tracking mirror 9, the third reflector 10, the fourth reflector 13, the sixth reflector 14, and the third beam splitter 16 and enters the second filter 19 and the first fine beacon receiving lens group 20, and finally forms an image on the first fine beacon detector 21. This optical path uses the beacon light spot information on the first fine beacon detector 21 to realize the closed-loop tracking of the first fine tracking mirror 9.

[0043] As Figure 5As shown in the figure, the short-wave infrared beacon receiving optical path D in this embodiment is composed of a main telescope 1, a second mirror 6, a fifth mirror 7, a compensation mirror group 8, a fine tracking mirror 1 9, a third mirror 10, a fourth mirror 13, a sixth mirror 14, a fine tracking mirror 2 22, a first beam splitter 23, a third filter 24, a second fine beacon receiving mirror group 25, and a second fine beacon detector 26. After the external short-wave infrared beacon light is received and beam-reduced by the main telescope 1, it passes through the fifth mirror 7, the compensation mirror group 8, the fine tracking mirror 1 9, the third mirror 10, the fourth mirror 13, the sixth mirror 14, the fine tracking mirror 2 22, and the first beam splitter 23 and is incident on the third filter 24 and the second fine beacon receiving mirror group 25, and finally forms an image on the second fine beacon detector 26. This optical path uses the beacon light spot information on the second fine beacon detector 26 to achieve closed-loop tracking of the fine tracking mirror 2 22.

[0044] As Figure 6 shown in the figure, the single-photon signal receiving optical path E in this embodiment is composed of a main telescope 1, a second mirror 6, a fifth mirror 7, a compensation mirror group 8, a fine tracking mirror 1 9, a third mirror 10, a fourth mirror 13, a sixth mirror 14, a fine tracking mirror 2 22, a first beam splitter 23, an optical booster 27, a second beam splitter 28, a single-photon signal receiving filter 32, a single-photon signal receiving mirror group 33, and a single-photon communication detector 34. After the external communication light is received and beam-reduced by the main telescope 1, it passes through the fifth mirror 7, the compensation mirror group 8, the fine tracking mirror 1 9, the third mirror 10, the fourth mirror 13, the sixth mirror 14, the fine tracking mirror 2 22, and the first beam splitter 23 and is incident on the optical booster 27. After being reflected by the second beam splitter 28, it is incident on the single-photon signal receiving filter 32 and the single-photon signal receiving mirror group 33, and finally is focused and incident on the single-photon communication detector 34. The single-photon communication detector 34 is used to complete the communication signal reception of the received signal light.

[0045] As Figure 7 shown in the figure, the single-photon beacon receiving optical path F in this embodiment is composed of a main telescope 1, a second mirror 6, a fifth mirror 7, a compensation mirror group 8, a fine tracking mirror 1 9, a third mirror 10, a fourth mirror 13, a sixth mirror 14, a fine tracking mirror 2 22, a first beam splitter 23, an optical booster 27, a second beam splitter 28, a single-photon beacon receiving filter 29, a single-photon beacon receiving mirror group 30, and a single-photon positioning detector 31. After the external communication light is received and beam-reduced by the main telescope 1, it passes through the fifth mirror 7, the compensation mirror group 8, the fine tracking mirror 1 9, the third mirror 10, the fourth mirror 13, the sixth mirror 14, the fine tracking mirror 2 22, and the first beam splitter 23 and is incident on the optical booster 27. After being reflected by the second beam splitter 28, it is incident on the single-photon beacon receiving filter 29 and the single-photon beacon receiving mirror group 30, and finally forms an image on the single-photon positioning detector 31. This optical path uses the single-photon positioning information on the single-photon positioning detector 31 for closed-loop tracking of the fine tracking mirror 2 22.

[0046] As shown Figure 8 in FIG. 1, the beacon emission optical path G in this embodiment is composed of a beacon / signal laser 35 and a beacon / signal transmitting antenna 36. The beacon light that meets the wavelength is emitted by the beacon laser 35 and is shaped, beam divergence angle compressed by the beacon / signal transmitting antenna 36, and is directed at the target and transmitted along with the theodolite two-dimensional turntable 11.

[0047] In this embodiment, the main telescope 1, the first reflector 2, the first filter 3, the coarse beacon receiving lens group 4, the coarse beacon detector 5, the second reflector 6, the fifth reflector 7, the compensation lens group 8, the first fine tracking mirror 9, the third reflector 10, the bi-directional corner cube prism group 12, the fourth reflector 13, the beacon / signal laser 35, and the beacon / signal transmitting antenna 36 are placed on the theodolite two-dimensional turntable 11; the target tracking of the theodolite two-dimensional turntable 11 is controlled by the electrical position feedback of the light spot on the coarse beacon detector 5.

[0048] In this embodiment, the main telescope 1 adopts a Cassegrain telescope, and tries to use the largest possible receiving field of view, which is preferably 4~8mrad. At the same time, it is matched with the compensation lens group 8 to achieve parallel light transmission at the end of the Coude optical path.

[0049] In this embodiment, the bi-directional corner cube prism group 12 is inserted into the optical path through a servo mechanism, and the aperture of the bi-directional corner cube prism group should be larger than the internal beam size, and 2 inches is preferred.

[0050] In this embodiment, an adaptive optical component is added between the fourth reflector 13 and the sixth reflector 14, and the time-domain and space-domain compensation for the atmospheric influence is realized through wavefront detection and wavefront correction. Considering that the aperture is significantly reduced, the corresponding number of adaptive optical component units can also be reduced to 32~64 units.

[0051] In this embodiment, the splitting ratio of the first beam splitter 23 needs to be divided according to the sensitivity characteristics of the second fine beacon detector 26, the single-photon positioning detector 31, and the single-photon communication detector 34, that is, the splitting ratio of the first beam splitter 23 , where is the sensitivity of the second fine beacon detector 26, in units of dBm; is the sensitivity of the single-photon positioning detector 31, in units of dBm; is the sensitivity of the single-photon communication detector 34, in units of dBm. In this embodiment, the sensitivity of the second fine beacon detector 26 is -72.5 dBm (generally between -72~-73dBm): the sensitivities of the single-photon positioning detector 31 and the single-photon communication detector 34 are both -75dBm. Therefore, in the design of this embodiment, the splitting ratio of the beam splitter should satisfy:

[0052] 。

Claims

1. A miniaturized satellite-ground laser communication terminal based on single-photon detection technology, comprising the following optical components: Main telescope (1), first reflector (2), first filter (3), coarse beacon receiving lens group (4), coarse beacon detector (5), second reflector (6), fifth reflector (7), compensation lens group (8), first fine tracking mirror (9), third reflector (10), bi-directional corner cube prism group (12), fourth reflector (13), sixth reflector (14), light trap (15), third beam splitter (16), signal emission lens group (17), signal light source (18), second filter (19), first fine beacon receiving lens group (20), first fine beacon detector (21), second fine tracking mirror (22), first beam splitter (23), third filter (24), second fine beacon receiving lens group (25), second fine beacon detector (26), optical booster (27), second beam splitter (28), single-photon beacon receiving filter (29), single-photon beacon receiving lens group (30), single-photon positioning detector (31), single-photon signal receiving filter (32), single-photon signal receiving lens group (33), single-photon communication detector (34), beacon / signal laser (35), beacon / signal transmitting antenna (36); It is characterized in that, The above optical components constitute an observation and reception optical path A, a signal transmission optical path B, a near-infrared beacon reception optical path C, a short-wave infrared beacon reception optical path D, a single-photon signal reception optical path E, a single-photon beacon reception optical path F, and a beacon transmission optical path G, where: The observation and reception optical path A consists of a main telescope (1), a first mirror (2), a first filter (3), a coarse beacon reception lens group (4), and a coarse beacon detector (5). After the external received beam is collected and focused by the main telescope (1), it is reflected by the first mirror (2), then passes through the first filter (3) and the coarse beacon reception lens group (4), and finally enters the coarse beacon detector (5) to complete the beacon light reception and positioning work. This optical path is used to measure the incident coarse beacon light; The signal transmission optical path B consists of a main telescope (1), a second mirror (6), a fifth mirror (7), a compensation mirror group (8), a first fine tracking mirror (9), a third mirror (10), a fourth mirror (13), a sixth mirror (14), a third beam splitter (16), a signal transmission mirror group (17), and a signal light source (18). First, the signal light source (18) sends a signal light of a specified wavelength, which is shaped by the signal transmission mirror group (17), then transmitted through the third beam splitter (16), and then reflected by the sixth mirror (14), the fourth mirror (13), the third mirror (10), and the first fine tracking mirror (9). After passing through the compensation mirror group (8), the fifth mirror (7), and the second mirror (6) again, it is shaped and focused by the main telescope (1) and then transmitted to the target; The near-infrared beacon reception optical path C consists of a main telescope (1), a second mirror (6), a fifth mirror (7), a compensation mirror group (8), a first fine tracking mirror (9), a third mirror (10), a fourth mirror (13), a sixth mirror (14), a third beam splitter (16), a second filter (19), a first fine beacon reception lens group (20), and a first fine beacon detector (21). The external beacon light is received and focused by the main telescope (1), then passes through the fifth mirror (7), the first fine tracking mirror (9), the third mirror (10), the fourth mirror (13), the sixth mirror (14), and the third beam splitter (16) and enters the second filter (19) and the first fine beacon reception lens group (20), and finally forms an image on the first fine beacon detector (21). This optical path uses the beacon light spot information on the first fine beacon detector (21) to achieve closed-loop tracking of the first fine tracking mirror (9); The short-wave infrared beacon receiving optical path D consists of a main telescope (1), a second mirror (6), a fifth mirror (7), a compensation mirror group (8), a first fine tracking mirror (9), a third mirror (10), a fourth mirror (13), a sixth mirror (14), a second fine tracking mirror (22), a first beam splitter (23), a third filter (24), a second fine beacon receiving mirror group (25), and a second fine beacon detector (26). After the external short-wave infrared beacon light is received and focused by the main telescope (1), it passes through the fifth mirror (7), the compensation mirror group (8), the first fine tracking mirror (9), the third mirror (10), the fourth mirror (13), the sixth mirror (14), the second fine tracking mirror (22), and the first beam splitter (23) and is incident on the third filter (24) and the second fine beacon receiving mirror group (25), and finally forms an image on the second fine beacon detector (26). The optical path uses the beacon light spot information on the second fine beacon detector (26) to achieve closed-loop tracking of the second fine tracking mirror (22); The single-photon signal receiving optical path E consists of a main telescope (1), a second mirror (6), a fifth mirror (7), a compensation mirror group (8), a first fine tracking mirror (9), a third mirror (10), a fourth mirror (13), a sixth mirror (14), a second fine tracking mirror (22), a first beam splitter (23), an optical booster (27), a second beam splitter (28), a single-photon signal receiving filter (32), a single-photon signal receiving mirror group (33), and a single-photon communication detector (34). After the external communication light is received and focused by the main telescope (1), it passes through the fifth mirror (7), the compensation mirror group (8), the first fine tracking mirror (9), the third mirror (10), the fourth mirror (13), the sixth mirror (14), the second fine tracking mirror (22), and the first beam splitter (23) and is incident on the optical booster (27). After being reflected by the second beam splitter (28), it is incident on the single-photon signal receiving filter (32) and the single-photon signal receiving mirror group (33), and finally is focused and incident on the single-photon communication detector (34). The single-photon communication detector (34) is used to complete the reception of the communication signal for the received signal light; The single-photon beacon receiving optical path F consists of a main telescope (1), a second mirror (6), a fifth mirror (7), a compensation mirror group (8), a first fine tracking mirror (9), a third mirror (10), a fourth mirror (13), a sixth mirror (14), a second fine tracking mirror (22), a first beam splitter (23), an optical booster (27), a second beam splitter (28), a single-photon beacon receiving filter (29), a single-photon beacon receiving mirror group (30), and a single-photon positioning detector (31). After the external communication light is received and reduced in beam by the main telescope (1), it passes through the fifth mirror (7), the compensation mirror group (8), the first fine tracking mirror (9), the third mirror (10), the fourth mirror (13), the sixth mirror (14), the second fine tracking mirror (22), and the first beam splitter (23) and then enters the optical booster (27). After being reflected by the second beam splitter (28), it enters the single-photon beacon receiving filter (29) and the single-photon beacon receiving mirror group (30), and finally forms an image on the single-photon positioning detector (31). This optical path uses the single-photon positioning information on the single-photon positioning detector (31) for closed-loop tracking of the second fine tracking mirror (22). The beacon transmitting optical path G consists of a beacon / signal laser (35) and a beacon / signal transmitting antenna (36). The beacon light with a suitable wavelength is emitted by the beacon laser (35) and shaped and beam divergence angle compressed by the beacon / signal transmitting antenna (36), and is sent while following the two-dimensional theodolite turntable (11) to point to the target. The splitting ratio of the first beam splitter (23) needs to divide the optical intensity according to the sensitivity characteristics of the second fine beacon detector (26), the single-photon positioning detector (31), and the single-photon communication detector (34), that is, the splitting ratio of the first beam splitter (23) where T1 is the sensitivity of the second fine beacon detector (26) in dBm; T2 is the sensitivity of the single-photon positioning detector (31) in dBm; T3 is the sensitivity of the single-photon communication detector (34) in dBm.

2. The miniaturized space-ground laser communication terminal based on single-photon detection technology according to claim 1, characterized in that, The main telescope (1), the first mirror (2), the first filter (3), the coarse beacon receiving lens group (4), the coarse beacon detector (5), the second mirror (6), the fifth mirror (7), the compensation mirror group (8), the first fine tracking mirror (9), the third mirror (10), the bi-directional corner cube prism group (12), the fourth mirror (13), the beacon / signal laser (35), and the beacon / signal transmitting antenna (36) are placed on the two-dimensional theodolite turntable (11). The target tracking of the two-dimensional theodolite turntable (11) is controlled by the electrical position feedback of the light spot on the coarse beacon detector (5).

3. The miniaturized space-ground laser communication terminal based on single-photon detection technology according to claim 1, characterized in that The main telescope (1) adopts a Cassegrain telescope.

4. A miniaturized space-ground laser communication terminal based on single-photon detection technology according to claim 1, characterized in that, The bi-directional corner cube prism group (12) is inserted into the optical path through a servo mechanism, and the aperture of the bi-directional corner cube prism group (12) should be greater than 2 inches.

5. The miniaturized space-to-ground laser communication terminal based on single-photon detection technology according to claim 1, wherein, An adaptive optical component is added between the fourth mirror (13) and the sixth mirror (14), and the adaptive optical component has 32 to 64 units.

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