An indoor laser wireless two-way communication system

Abstract

This application belongs to the field of laser communication technology, specifically disclosing an indoor laser wireless two-way communication system, including: a first terminal and a second terminal. Each terminal is equipped with a beam combining transmission optical path and a beacon light transmission optical path. A signal light collimator, a dichroic mirror, and a two-axis deflector are sequentially arranged on the beam combining transmission optical path. A beacon light processing module and a dichroic mirror are arranged on the beacon light transmission optical path. The beacon light processing module generates beacon light and acquires images of the received beacon light. The terminal is also equipped with a control module and a wide-angle camera. The control module acquires environmental images through the wide-angle camera, analyzes and adjusts the two-axis deflector, and analyzes the acquired beacon light images and adjusts the two-axis deflector. This application, through the wide-angle camera and two-axis deflector, can achieve a large working field of view. Furthermore, through two-stage alignment between the first and second terminals, it can achieve high-speed two-way laser communication with a large field of view and low link loss.

Description

Technical Field

[0001] This application belongs to the field of laser communication technology, and more specifically, relates to an indoor laser wireless two-way communication system. Background Technology

[0002] In recent years, with the continuous increase in communication equipment and the ever-increasing demands for communication speeds, the spectrum resources of traditional radio frequency signals have become increasingly congested. Therefore, laser communication, which uses lasers with higher frequencies and shorter wavelengths as carriers, has become a research hotspot. Laser communication boasts advantages such as high capacity, abundant spectrum resources, resistance to electromagnetic interference, and high security, making it suitable for various indoor environments such as data centers, hospitals, factories, and homes. Consequently, the use of lasers to establish high-speed connections with user terminals in indoor environments is gradually gaining attention.

[0003] Since laser divergence angles are typically on the order of milliradians (mrad), alignment control is the most critical aspect of laser communication. Especially to adapt to existing fiber optic networks and achieve seamless connections between fiber optic and free-space links, laser communication terminals need to couple the receiving light into single-mode fiber, which presents a greater challenge to link alignment. Existing indoor optical wireless systems struggle to simultaneously meet requirements such as wide range, low loss, high speed, full-duplex operation, and miniaturization, often exhibiting significant link loss. This necessitates the use of erbium-doped fiber amplifiers at the receiving end to amplify the received signal, further increasing system complexity and cost. Achieving high-speed, bidirectional laser communication with a wide field of view and low link loss suitable for indoor use is a pressing technical problem to be solved in this field. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to realize high-speed bidirectional laser communication with a large field of view and low link loss suitable for indoor use.

[0005] To achieve the above objectives, this application provides an indoor laser wireless two-way communication system, comprising: a first terminal and a second terminal, wherein the terminal is configured with a beam combining transmission optical path and a beacon optical transmission optical path;

[0006] A signal light collimator, a dichroic mirror, and a two-axis deflector are sequentially arranged on the beam-combining transmission optical path.

[0007] A beacon light processing module and a dichroic mirror are installed on the beacon light transmission optical path;

[0008] The beam combining transmission optical path intersects with the beacon light transmission optical path at a dichroic mirror;

[0009] A signal light collimator is used to generate signal light and process the received signal light;

[0010] The beacon light processing module is used to generate beacon light and acquire images of the received beacon light;

[0011] Dichroic mirrors are used to transmit signal light in the beam combining transmission optical path and to reflect beacon light between the two-axis deflection mirror in the beam combining transmission optical path and the beacon light processing module in the beacon light transmission optical path.

[0012] Two-axis deflection mirrors are used to reflect signal light and beacon light between the beam combining transmission optical path and the input / output optical path of this terminal;

[0013] The terminal is also equipped with a control module and a wide-angle camera;

[0014] The control module is used to acquire environmental images through a wide-angle camera, analyze the position of another terminal in the environmental images and adjust the two-axis deflection mirror so that the optical axis of this terminal initially points to the other terminal, and analyze the position of the beacon light in the acquired beacon light image and adjust the two-axis deflection mirror so that the received beacon light coincides with the optical axis of this terminal.

[0015] In one possible implementation, the beacon light processing module of the second terminal includes: a beam splitter, a retroreflection prism, a reflector, a focusing lens, and a visible light camera;

[0016] Accordingly, a dichroic mirror, a beam splitter, and a retroreflection prism are sequentially arranged on the beacon light transmission optical path of the second terminal;

[0017] Correspondingly, the second terminal is also equipped with a first beacon light receiving optical path and a second beacon light receiving optical path. A beam splitter, a lens and a visible light camera are arranged sequentially on the two beacon light receiving optical paths. A reflector is also arranged on the second beacon light receiving optical path. The reflector and the lens are arranged on both sides of the beam splitter.

[0018] The beacon light transmission optical path, the first beacon light receiving optical path, and the second beacon light receiving optical path intersect at the beam splitter;

[0019] The beam splitter of the second terminal is used to reflect the first beacon light between the dichroic mirror in the beacon light transmission optical path and the lens in the first beacon light receiving optical path, and to transmit the first beacon light to the retroreflection prism in the beacon light transmission optical path. The first beacon light is generated by the first terminal.

[0020] The retroreflection prism is used to receive the first beacon light in the beacon light transmission optical path and reflect the received first beacon light along the beacon light transmission optical path to the beam splitter. The light reflected by the retroreflection prism is used as the second beacon light.

[0021] The beam splitter of the second terminal is also used to reflect the second beacon light to the reflector and transmit the second beacon light to the dichroic mirror along the beacon light transmission path;

[0022] The reflector is used to receive the second beacon light from the beam splitter and reflect the second beacon light back to the beam splitter along the receiving optical path of the second beacon light;

[0023] The beam splitter of the second terminal is also used to receive the second beacon light from the reflector and transmit the second beacon light to the lens in the second beacon light receiving optical path.

[0024] In one possible implementation, the control module of the second terminal is used for:

[0025] Determine a first distance x1 of the first light spot in the horizontal direction relative to the center of the visible light camera, and determine a second distance x2 of the second light spot in the horizontal direction relative to the center of the visible light camera;

[0026] Based on the first distance x1 and the second distance x2, a third distance d is determined between the emission point of the first beacon light and the optical axis of the second terminal;

[0027] Based on the third distance d and the fourth distance L between the two ends, the angle to be deflected by the two-axis deflecting mirror is determined.

[0028] In one possible implementation, the control module of the second terminal is also used to determine the third distance d using the following formula:

[0029] f×x1=-c×d+θ×(f 2 +f×cc×Lc×(a+b1+b4));

[0030] f×x2=-c×d+θ×(f 2 +f×cc×Lc×(a+b1+2b2+2b3+b4))+κ;

[0031] Where f represents the focal length of the lens, c represents the distance between the image frame and the focal plane of the visible light camera, a represents the distance between the two-axis deflection mirror of the second terminal and the dichroic mirror of the second terminal, b1 represents the distance from the beam splitter to the dichroic mirror, b2 represents the distance from the beam splitter to the retroreflection prism, b3 represents the distance from the beam splitter to the reflecting mirror, b4 represents the distance from the beam splitter to the lens, θ represents the angle between the optical axes of the two terminals, and κ is determined based on the tilt angle of the reflecting mirror.

[0032] In one possible implementation, the control module of the second terminal is also used to determine the angle to be deflected using the following formula.

[0033] In one possible implementation, the control module of the second terminal is also used for:

[0034] If we determine that d = 0 and θ = θ0, then we determine that θ0 is the disturbance angle generated by the first terminal, and θ represents the angle between the optical axes of the two terminals.

[0035] If we determine that d = L × θ0 and θ = θ0, then we determine that θ0 is the disturbance angle generated by the second terminal, and control the two-axis deflection mirror of the second terminal to rotate θ0 / 2.

[0036] In one possible implementation, the beacon light processing module of the first terminal includes: a beacon light laser, a beam splitter, and a beacon light image acquisition module;

[0037] Accordingly, a beacon laser, a beam splitter, and a dichroic mirror are sequentially arranged on the beacon light transmission optical path of the first terminal;

[0038] Correspondingly, the first terminal is also equipped with a beacon light receiving optical path, and a beam splitter and a beacon light image acquisition module are set on the beacon light receiving optical path of the first terminal;

[0039] The beacon light transmission optical path and the beacon light receiving optical path of the first terminal intersect at the beam splitter;

[0040] A beacon laser is used to generate the first beacon beam;

[0041] The beam splitter of the first terminal is used to transmit the first beacon light in the beacon light transmission optical path and reflect the second beacon light between the dichroic mirror in the beacon light transmission optical path and the beacon light image acquisition module in the beacon light receiving optical path. The second beacon light is reflected by the second terminal through the retroreflection prism.

[0042] The beacon light image acquisition module is used to acquire images of the received second beacon light.

[0043] In one possible implementation, the beacon light image acquisition module includes a lens for focusing and a visible light camera, wherein the image frames of the two visible light cameras at the two terminals are not located at the focal plane of the lens.

[0044] In one possible implementation, the control module of the first terminal is used for:

[0045] Control the scanning of the two-axis deflection mirror;

[0046] If it is determined that the second beacon light is fully received by the first terminal, the two-axis deflection mirror is controlled to deflect until the second beacon light is located at the center of the visible light camera's image, so that the received second beacon light coincides with the optical axis of the second terminal.

[0047] In one possible implementation, the control module is used for:

[0048] Based on the position of another terminal in the environmental image, determine the angle α of the line connecting the other terminal and the wide-angle camera of this terminal relative to the optical axis of the wide-angle camera of this terminal. Cy ;

[0049] Based on angle α CyThe following formula is used to determine the angle α to be deflected by the two-axis deflecting mirror. FSMy ;

[0050]

[0051] Where, Δd y H represents the distance between the visible light camera and the two-axis deflection mirror, and H represents the height difference between the two ends.

[0052] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:

[0053] (1) A wide-angle camera and a two-axis deflection mirror can be used to achieve a wide working field of view. Then, through two-stage alignment between the first terminal and the second terminal, precise alignment between the first terminal and the second terminal can be achieved in a wide working field of view. Under precise alignment, the communication link loss is low. Then, the two terminals generate signal light through the internal beam-combining transmission optical path and process the received signal light to achieve high-speed bidirectional laser communication with a large field of view and low link loss.

[0054] (2) When there is a disturbance in one or both of the two terminals, the two terminals can automatically adjust the two-axis deflection mirrors to perform rotation compensation, and either terminal can keep pointing accurately at the other terminal to achieve stable duplex communication indoors. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of an indoor laser wireless two-way communication system provided in an embodiment of this application;

[0056] Figure 2 This is a schematic diagram of the system structure of the laser communication terminal provided in the embodiments of this application;

[0057] Figure 3 This is a schematic diagram of the initial pointing of the first terminal in the Y direction provided in the embodiments of this application;

[0058] Figure 4 This is the optical path diagram of the first beacon light of the visible light camera focused on the second terminal, provided in an embodiment of this application;

[0059] Figure 5 This is an optical path diagram of the second beacon light of a visible light camera focused on a second terminal, provided in an embodiment of this application.

[0060] Figure 6 This is the optical path diagram of the second beacon light from the visible light camera that returns to the first terminal, as provided in the embodiments of this application.

[0061] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0062] 10: First terminal; 11: First beacon light processing module; 101: First signal light collimator; 102: First two-axis deflection mirror; 103: First wide-angle camera; 104: First control module; 105: Beacon light laser; 106: First beam splitter; 107: Beacon light image acquisition module; 701: First lens; 702: First visible light camera; 108: First dichroic mirror; 20: Second terminal; 21: Second beacon light processing module; 201: Second signal light collimator; 202: Second two-axis deflection mirror; 203: Second wide-angle camera; 204: Second control module; 206: Second dichroic mirror; 501: Second beam splitter; 502: Retroreflection prism; 503: Reflector; 504: Second lens; 505: Second visible light camera. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0064] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. For example, "first terminal" and "second terminal," etc., are used to distinguish different terminals, not to describe a specific order of terminals.

[0065] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0066] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0067] The embodiments of this application are described below with reference to the accompanying drawings.

[0068] Figure 1 This is a schematic diagram of an indoor laser wireless two-way communication system provided in an embodiment of this application, as shown below. Figure 1As shown, the indoor laser wireless two-way communication system provided in this application includes: a first terminal on the access side (which can be placed on the ceiling or side wall of the room) and a second terminal on the user side (which can be placed below the first terminal), constituting full-duplex laser communication, with a working range covering the entire room. Figure 1 In Chinese, OLT stands for Optical Line Terminal.

[0069] Figure 2 This is a schematic diagram of the system structure of the laser communication terminal provided in the embodiments of this application, as shown below. Figure 2 As shown, the system includes: a first terminal 10 and a second terminal 20.

[0070] The terminal (first terminal or second terminal) is equipped with a beam combining transmission optical path and a beacon light transmission optical path; a signal light collimator, a dichroic mirror and a two-axis deflector are sequentially arranged on the beam combining transmission optical path; a beacon light processing module and a dichroic mirror are arranged on the beacon light transmission optical path; the beam combining transmission optical path and the beacon light transmission optical path intersect at the dichroic mirror.

[0071] The signal light collimator is used to generate signal light (e.g., 1550nm signal light) and process the received signal light; the beacon light processing module is used to generate beacon light (e.g., 780nm beacon light) and acquire images of the received beacon light.

[0072] For example, both the beacon light divergence angle and the signal light divergence angle are on the order of mrad, and the beacon light energy is on the order of 100 nW, which helps to reduce the power consumption of the system.

[0073] Dichroic mirrors are used to transmit signal light on the beam combining transmission optical path and to reflect beacon light between the two-axis deflector on the beam combining transmission optical path and the beacon light processing module on the beacon light transmission optical path; the two-axis deflector is used to reflect signal light and beacon light between the beam combining transmission optical path and the input / output optical path of this terminal.

[0074] The terminal is also equipped with a control module and a wide-angle camera. The control module is used to acquire environmental images through the wide-angle camera, analyze the position of another terminal in the environmental images, and adjust the two-axis deflection mirror to initially point the optical axis of this terminal towards the other terminal. It also analyzes the position of the beacon light in the acquired beacon light image and adjusts the two-axis deflection mirror to ensure that the received beacon light coincides with the optical axis of this terminal, i.e., the received beacon light coincides with the signal light of this terminal. Specifically, the optical axis of the terminal refers to the optical axis of the signal light collimator. Regarding the initial pointing, since analyzing the position of the other terminal in the environmental images and adjusting the two-axis deflection mirror (this is the initial pointing stage in the two-stage alignment process, which will be explained in detail below), the optical axis of this terminal can be made to roughly point towards the other terminal. Therefore, the optical axis pointing in this case is called the initial pointing.

[0075] Specifically, such as Figure 2 As shown, the first terminal 10 in the system includes: a first beacon light processing module 11, a first signal light collimator 101, a first two-axis deflection mirror 102, a first wide-angle camera 103, a first control module 104, and a first dichroic mirror 108.

[0076] A first signal light collimator 101, a first dichroic mirror 108, and a first two-axis deflector 102 are sequentially arranged on the beam combining transmission optical path of the first terminal 10. A first beacon light processing module 11 and a first dichroic mirror 108 are arranged on the beacon light transmission optical path of the first terminal 10.

[0077] Optionally, the first beacon light processing module 11 includes: a beacon light laser 105, a first beam splitter 106, and a beacon light image acquisition module 107.

[0078] Optionally, the beacon light image acquisition module 107 includes a first lens 701 and a first visible light camera 702.

[0079] like Figure 2 As shown, the second terminal 20 in the system includes: a second beacon light processing module 21, a second signal light collimator 201, a second two-axis deflection mirror 202, a second wide-angle camera 203, a second control module 204, and a second dichroic mirror 206.

[0080] A second signal light collimator 201, a second dichroic mirror 206, and a second two-axis deflector 202 are sequentially arranged on the beam combining transmission optical path of the second terminal 20. A second beacon light processing module 21 and a second dichroic mirror 206 are arranged on the beacon light transmission optical path of the second terminal 20.

[0081] Optionally, the second beacon light processing module 21 includes: a second beam splitter 501, a retroreflection prism 502, a reflector 503, a second lens 504, and a second visible light camera 505.

[0082] Wide-angle cameras have shorter focal lengths and a wider field of view, ensuring that the opposite end can be captured. Two-axis deflecting mirrors have vertical tilt and horizontal rotation axes, ensuring that the optical axis of the end lens is pointed towards the opposite end within the wide field of view.

[0083] If this terminal is the first terminal, then the other end is the second terminal; if this terminal is the second terminal, then the other end is the first terminal.

[0084] In the beacon light transmission optical path, a first beacon light can be generated by the beacon light processing module. Then, a dichroic mirror reflects the first beacon light between the beacon light processing module in the beacon light transmission optical path and the two-axis deflecting mirror in the beam combining transmission optical path. Then, the two-axis deflecting mirror reflects the first beacon light between the beam combining transmission optical path and the input / output optical path of this terminal. Finally, the first beacon light is emitted along the input / output optical path of this terminal, thus realizing the emission of beacon light.

[0085] On the beacon light transmission optical path, the second beacon light (emitted by the other end) can be received along the input and output optical paths of this terminal. Then, the two-axis deflecting mirror reflects the second beacon light between the input and output optical paths of this terminal and the beam combining transmission optical path. Then, the dichroic mirror reflects the second beacon light between the two-axis deflecting mirror on the beam combining transmission optical path and the beacon light processing module on the beacon light transmission optical path. Then, the beacon light processing module acquires an image of the received second beacon light to realize the reception of beacon light.

[0086] A beam-combined optical transmission path can transmit beacon light and signal light in a combined manner. The transmission of beacon light via a beam-combined optical transmission path has been explained above; the transmission of signal light via a beam-combined optical transmission path will be explained below.

[0087] In the beam combining transmission optical path, a first signal light can be generated by a signal light collimator, and then a dichroic mirror transmits the first signal light in the beam combining transmission optical path. Then, a two-axis deflecting mirror is used to reflect the signal light between the beam combining transmission optical path and the input / output optical path of this terminal. Then, the first signal light is emitted along the input / output optical path of this terminal to realize the emission of signal light.

[0088] In the beam combining transmission optical path, the second signal light (emitted by the other end) can be received along the input and output optical paths of this terminal. Then, the two-axis deflection mirror reflects the second signal light between the input and output optical paths of this terminal and the beam combining transmission optical path. Then, the dichroic mirror transmits the second signal light in the beam combining transmission optical path. Then, the signal light collimator processes the received second signal light to realize the reception of the signal light.

[0089] The process of transmitting and receiving beacon light and signal light by the terminal has been explained above. The two-stage alignment process between the two terminals will be explained below.

[0090] In the first stage of the two-stage alignment process (or the initial pointing stage), the control module of this terminal acquires environmental images using a wide-angle camera, analyzes the position of the other terminal (the peer) in the environmental images, and adjusts the two-axis deflection mirrors to initially point the optical axis of this terminal towards the other terminal. After completing the initial pointing of the optical axis of this terminal towards the other terminal, this terminal can receive the beacon light emitted by the peer terminal, and then acquire an image of the received beacon light through the beacon light processing module.

[0091] In the second stage of the two-stage alignment process (or the fine alignment stage), the control module of this terminal analyzes the position of the beacon light in the acquired beacon light image and adjusts the two-axis deflection mirrors to ensure that the received beacon light coincides with the optical axis of this terminal. After the two terminals complete the two-stage alignment, precise alignment between the two terminals can be achieved, ensuring that the optical axes of the two terminals coincide.

[0092] Therefore, by using a wide-angle camera and a two-axis deflection mirror, a large working field of view can be achieved. Furthermore, through two-stage alignment between the first and second terminals, precise alignment between the first and second terminals can be achieved within the large working field of view. Under precise alignment, the communication link loss is low. Subsequently, the two terminals generate signal light (sent to the other end) through the internal beam-combining transmission optical path and process the signal light received (from the other end), thereby achieving high-speed bidirectional laser communication with a large field of view and low link loss.

[0093] like Figure 2 As shown, in one possible implementation, the second beacon light processing module 21 of the second terminal includes: a second beam splitter 501, a retroreflection prism 502 (which can be replaced by a reflector), a reflector 503, a second lens 504 for focusing, and a second visible light camera 505.

[0094] Accordingly, a second dichroic mirror 206, a second beam splitter 501, and a retroreflection prism 502 are sequentially arranged on the beacon light transmission optical path of the second terminal.

[0095] Correspondingly, the second terminal is also equipped with a first beacon light receiving optical path and a second beacon light receiving optical path. A second beam splitter 501, a second lens 504 and a second visible light camera 505 are sequentially arranged on the two beacon light receiving optical paths. A reflector 503 is also arranged on the second beacon light receiving optical path. The reflector 503 and the second lens 504 are arranged on both sides of the second beam splitter 501.

[0096] The beacon light transmission optical path, the first beacon light receiving optical path, and the second beacon light receiving optical path intersect at the beam splitter;

[0097] The beam splitter of the second terminal is used to reflect the first beacon light (generated by the first terminal) between the second dichroic mirror 206 in the beacon light transmission optical path and the second lens 504 in the first beacon light receiving optical path, and to transmit the first beacon light to the retroreflection prism 502 in the beacon light transmission optical path.

[0098] The retroreflection prism 502 is used to receive the first beacon light in the beacon light transmission optical path and reflect the received first beacon light along the beacon light transmission optical path to the second beam splitter 501. The light reflected by the retroreflection prism 502 serves as the second beacon light.

[0099] The second beam splitter 501 of the second terminal is also used to reflect the second beacon light to the reflector 503 and transmit the second beacon light to the second dichroic mirror 206 along the beacon light transmission optical path.

[0100] The reflector 503 is used to receive the second beacon light from the second beam splitter 501 and reflect the second beacon light back to the second beam splitter 501 along the receiving optical path of the second beacon light;

[0101] The second beam splitter 501 of the second terminal is also used to receive the second beacon light from the reflector 503 and transmit the second beacon light to the second lens 504 in the second beacon light receiving optical path.

[0102] In one possible implementation, the control module of the second terminal is specifically used for:

[0103] Determine a first distance x1 of the first light spot in the horizontal direction relative to the center of the second visible light camera 505, and determine a second distance x2 of the second light spot in the horizontal direction relative to the center of the second visible light camera 505;

[0104] Based on the first distance x1 and the second distance x2, a third distance d is determined between the emission point of the first beacon light and the optical axis of the second terminal;

[0105] Based on the third distance d and the fourth distance L between the two terminals (the second control module 204 performs image recognition on the environmental image captured by the second wide-angle camera 203 to determine the distance L), the angle to be deflected by the second two-axis deflecting mirror 202 is determined. The second control module 204 adjusts the angle to be deflected. Adjust the second two-axis deflection mirror 202 so that the received beacon light coincides with the optical axis of this terminal.

[0106] In one possible implementation, the second control module 204 of the second terminal is further configured to determine the third distance d using the following formula:

[0107] f×x1=-c×d+θ×(f 2 +f×cc×Lc×(a+b1+b4));

[0108] f×x2=-c×d+θ×(f 2 +f×cc×Lc×(a+b1+2b2+2b3+b4))+κ;

[0109] Where f represents the focal length of the lens, c represents the distance between the image frame of the second visible light camera 505 and the focal plane, a represents the distance between the second two-axis deflection mirror 202 of the second terminal and the second dichroic mirror 206 of the second terminal, b1 represents the distance from the beam splitter to the dichroic mirror, b2 represents the distance from the beam splitter to the retroreflection prism, b3 represents the distance from the beam splitter to the reflector, b4 represents the distance from the beam splitter to the lens, θ represents the angle between the optical axes of the two terminals, and κ is determined based on the tilt angle of the reflector 503.

[0110] In one possible implementation, the second control module 204 of the second terminal is further configured to determine the angle to be deflected using the following formula.

[0111] In one possible implementation, the second control module 204 of the second terminal is further used for:

[0112] If we determine that d = 0 and θ = θ0, then we determine that θ0 is the disturbance angle generated by the first terminal.

[0113] If d = L × θ0 and θ = θ0 is determined, then θ0 is determined to be the disturbance angle generated by the second terminal, and the second two-axis deflection mirror 202 of the second terminal is controlled to rotate θ0 / 2.

[0114] In one possible implementation, the first beacon light processing module 11 of the first terminal includes: a beacon light laser 105, a first beam splitter 106, and a beacon light image acquisition module 107.

[0115] Accordingly, a beacon laser 105, a first beam splitter 106, and a first dichroic mirror 108 are sequentially arranged on the beacon light transmission optical path of the first terminal;

[0116] Accordingly, the first terminal is also equipped with a beacon light receiving optical path, and a first beam splitter 106 and a beacon light image acquisition module 107 are provided on the beacon light receiving optical path of the first terminal.

[0117] The beacon light transmission optical path and the beacon light receiving optical path of the first terminal intersect at the first beam splitter 106;

[0118] Beacon laser 105 is used to generate the first beacon light;

[0119] The first beam splitter 106 of the first terminal is used to transmit the first beacon light in the beacon light transmission optical path and reflect the second beacon light between the first dichroic mirror 108 in the beacon light transmission optical path and the beacon light image acquisition module 107 in the beacon light receiving optical path. The second beacon light is reflected by the second terminal through the retroreflection prism.

[0120] The beacon light image acquisition module 107 is used to acquire images of the received second beacon light.

[0121] Understandably, after the first beacon light is transmitted through the first beam splitter 106, it is combined with the first signal light (the signal light generated by the first terminal) by the first dichroic mirror 108 to obtain a combined beam. The combined beam is then reflected by the first two-axis deflector 102 and then exits from the first terminal. After the second signal light (the signal light generated by the second terminal) is incident on the first terminal, it is reflected by the first two-axis deflector 102, then by the first dichroic mirror 108, and then incident on the first signal light collimator 101. After the second beacon light is incident on the first terminal, it is reflected by the first two-axis deflector 102, then by the first dichroic mirror 108, and then by the first beam splitter 106 to the beacon light image acquisition module 107.

[0122] Therefore, the structure of the first terminal and the structure of the second terminal can be asymmetrical. The second terminal located on the user side does not need a beacon laser, which reduces the size and power consumption of the user-side terminal.

[0123] In one possible implementation, the beacon light image acquisition module 107 includes a first lens 701 for focusing and a first visible light camera 702, wherein the image frames of the two terminal visible light cameras are not located at the focal plane of the lens. For example, the image frames of the visible light cameras are located in front of or behind the focal plane.

[0124] It should be noted that when the visible light camera is located at the focal plane of the lens, the visible light camera can only detect the angle between the (received) beacon light and the optical axis of the terminal, that is, the angle between the optical axes of the two terminals. This causes the communication system to only ensure that the optical axes of the two laser terminals are parallel, but not to ensure that the two optical axes coincide. This results in a lateral mismatch between the optical axes when coupled to a single-mode fiber, increasing the link loss.

[0125] In this embodiment, the visible light cameras of the two terminals are positioned outside the focal plane of the lens. This ensures that for the first terminal, parallel but differently spaced second beacon beams will be focused at different locations. Only when the first terminal deflects its emitted beacon beam to θ1 (the angle between the first terminal's emission optical axis and the line connecting the two terminals) to 0 will the returning second beacon beam coincide with the first terminal's optical axis and enter the center of the first terminal's visible light camera. For the second terminal, the first beacon beam forms a first spot on the visible light camera's image, and the second beacon beam forms a second spot. The second terminal can then adjust its two-axis deflection mirror based on the positions of the first and second spots to ensure the received beacon beam coincides with its own optical axis. Therefore, by positioning the visible light cameras of the two terminals outside the focal plane of the lens, the optical axes of the two terminals are ensured to coincide, preventing lateral mismatch between optical axes when coupled to single-mode fiber and reducing link loss.

[0126] In one possible implementation, the first control module 104 of the first terminal is used for:

[0127] Control the scanning of the first two-axis deflection mirror 102;

[0128] If it is determined that the second beacon light is fully received by the first terminal, the first two-axis deflection mirror 102 is controlled to deflect until the second beacon light is located at the center of the image of the first visible light camera 702, so that the received second beacon light coincides with the optical axis of the second terminal.

[0129] In one possible implementation, the control module (either the first or the second control module) is used for:

[0130] Based on the position of another terminal in the environmental image, determine the angle α of the line connecting the other terminal and the wide-angle camera of this terminal relative to the optical axis of the wide-angle camera of this terminal. Cy ;

[0131] Based on angle α Cy The following formula is used to determine the angle α to be deflected by the two-axis deflecting mirror. FSMy ;

[0132]

[0133] Where, Δd y H represents the distance between the visible light camera and the two-axis deflection mirror, and H represents the height difference between the two ends.

[0134] It is understandable that the control module of this terminal is based on the angle α to be deflected. FSMy Adjust the two-axis deflection mirrors so that the optical axis of this terminal initially points to the other terminal, thus completing the initial pointing.

[0135] The following is in conjunction with the appendix Figure 3-6 The working principle of the indoor laser wireless two-way communication system provided in the embodiments of this application will be explained.

[0136] Figure 3 This is a schematic diagram of the initial pointing of the first terminal in the Y direction according to an embodiment of this application, as shown below. Figure 3 As shown, since a two-axis (fast) deflection mirror and a wide-field-of-view wide-angle camera (a visible light camera with a wide-angle lens) are used, the initial pointing process in the X direction is also the same. The parallelism of the first wide-angle camera 103 of the first terminal and the beam emitted from the first two-axis deflection mirror 102 is pre-calibrated. The first wide-angle camera 103 first captures an image, and then the first control module 104 performs image recognition on the frame containing the entire scene to obtain the angle αC of the second terminal relative to the first wide-angle camera 103. y Then, based on the distance Δd between the first wide-angle camera 103 and the first two-axis deflection mirror 102... y (Preset value), the height difference H between the terminals (which can be obtained through image recognition), yields the angle α that the emitted beam needs to be deflected. FSMy :

[0137]

[0138] Thus, the first control module 104 provides feedback control to the first two-axis deflection mirror 102 to deflect, completing the initial pointing of the first terminal. The initial pointing process of the second terminal is similar.

[0139] After initial pointing, both terminals enter the acquisition state. The acquisition process adopts the classic staring-scanning method. The first terminal controls the first two-axis deflection mirror 102 to deflect so that the emitted beacon light scans within the uncertain region where the second terminal is located. The second terminal has a larger field of view and maintains the initial pointing while staring until two beacon light spots are present on the second visible light camera 505 of the second terminal. At this point, the second terminal has acquired the first terminal.

[0140] Figure 4 This is the optical path diagram of the first beacon light of the visible light camera focused on the second terminal, as provided in the embodiments of this application. Figure 4 As shown, the first beacon light is focused onto the second visible light camera 505 after being reflected by the second two-axis deflecting mirror 202, the second dichroic mirror 206, and the second beam splitter 501. Since these three devices only reflect the beacon light, for ease of description, the reflected and folded light path is unfolded onto a single axis. Figure 5 , Figure 6 The same unfolding method is also used to intuitively reflect the alignment principle. Due to the similarity of the alignment principle and process in the horizontal and vertical directions, the following discussion assumes that it is in the horizontal direction, while the vertical alignment process is the same.

[0141] After the first terminal is captured by the second terminal, the first beacon light passes through the second beam splitter 501, and a portion of the first beacon light is directly reflected into the second visible light camera 505, forming a light spot 1. According to geometric optics, the distance x1 of the light spot 1 in the horizontal direction relative to the center of the second visible light camera 505 satisfies the following equation:

[0142] f×x1=-c×d+θ×(f 2 +f×cc×Lc×(a+b1+b4));

[0143] Where f is the focal length of the second lens 504, c is the distance between the image frame of the second visible light camera 505 and the focal plane, L is the distance between the two terminals, a is the distance between the second two-axis deflecting mirror 202 and the second dichroic mirror 206 of the second terminal, b1 represents the distance from the beam splitter to the dichroic mirror, b2 represents the distance from the beam splitter to the retroreflection prism, b3 represents the distance from the beam splitter to the reflecting mirror, and b4 represents the distance from the beam splitter to the lens. All of the above parameters are fixed constants. The position of the light spot is determined by the distance d from the beacon light emission point to the optical axis of the second terminal and the angle θ between the optical axes of the two terminals.

[0144] Figure 5 This is an optical path diagram of the second beacon light focused onto the second terminal by a visible light camera, as provided in an embodiment of this application. Figure 5 As shown, the first beacon light entering the second terminal is partially reflected by the second beam splitter 501 and then directly transmitted through it. It is reflected again by the retroreflection prism 502 (the light reflected by the retroreflection prism serves as the second beacon light), and then reflected by the second beam splitter 501 onto the reflecting mirror 503. The reflecting mirror 503 reflects the second beacon light, which is then transmitted through the second beam splitter 501 and focused onto the second visible light camera 505, forming spot 2. The reflecting mirror 503 is tilted at a certain angle, so spot 2 does not coincide with spot 1. Therefore, the centroids of the two spots can be obtained using the contour method, and their positions on the image frame of the second visible light camera 505 can be determined. The difference between spot 1 and spot 2 is that spot 2 is reflected by the retroreflection prism 502 and the reflecting mirror 503, resulting in an additional optical path. According to geometric optics, the horizontal distance x2 of spot 2 relative to the center of the second visible light camera 505 satisfies the following equation:

[0145] f×x2=-c×d+θ×(f 2 +f×cc×Lc×(a+b1+2b2+2b3+b4))+κ;

[0146] Among them, κ is determined by the tilt angle of the mirror and is a constant.

[0147] The equations satisfied by distance x1 and distance x2 together constitute a system of two linear equations in two variables concerning distance d and the included angle θ. Therefore, after calibrating the constant terms above, d and θ can be obtained based on the spot positions x1 and x2. The centroid coordinates of the spot positions x1 and x2 are obtained using the contour method, and then calculated based on the pixel size and center coordinates of the second visible light camera 505. Finally, the second terminal controls the second two-axis deflector 202 based on the calculation results, with the deflection angle being:

[0148]

[0149] At this point, the second terminal is precisely pointed at the first terminal, completing the alignment of the second terminal.

[0150] Figure 6 This is the optical path diagram of the second beacon light returned to the first terminal by the visible light camera, as provided in the embodiments of this application. Figure 6 As shown, after the second terminal is aligned, the first visible light camera 702 of the first terminal detects the returning second beacon light. Due to the characteristic that the backlight angle returns the beam by 180°, the second beacon light incident back to the first terminal is parallel to the emitted first beacon light, and the distance between them is determined by the angle θ1 between the emitted optical axis of the first terminal and the line connecting the two terminals.

[0151] Then, the first terminal enters the fine alignment stage. The image frame of the first visible light camera 702 of the first terminal is not at the focal plane (for example, the image frame of the visible light camera is in front of or behind the focal plane). In this way, the returning second beacon lights, which are parallel but spaced differently, will be focused at different positions. Only when the first terminal controls the outgoing beacon light to deflect to θ1 = 0, will the returning second beacon light coincide with the optical axis of the first terminal and enter the center of the visible light camera of the first terminal.

[0152] Therefore, after ensuring that all the returned beacon light is received by the first terminal, the first terminal controls the two-axis deflection mirror to deflect until the focused beacon light is located at the center of the visible light camera, thus completing the alignment of the first terminal.

[0153] This completes the alignment of the first and second terminals, avoiding the situation where the optical axes of the two terminals are parallel but not coincident, thus reducing the link loss of the system.

[0154] Once the two ends are aligned, the signal light emitted by this terminal can be received by the signal light collimator at the other end, and then the signal light collimator at the other end can couple the received signal light into the optical fiber to achieve bidirectional communication.

[0155] It is worth noting that when a terminal experiences environmental disturbances, causing it to shift or rotate, in full-duplex communication, the visible light camera on the local terminal will detect the change in the light spot, while simultaneously the visible light camera on the remote end will also detect the change in the light spot's position. Without other means, each end will control its own deflection mechanism based on the change in the light spot, causing a disturbance on one end to cause deflection in both terminals, thus degrading link stability.

[0156] Considering environmental disturbances after alignment, such as rotational disturbances only occurring at the first terminal, the light spot on the visible light camera of the first terminal will deviate from the center. This will drive the two-axis deflection mirror of the first terminal to deflect and maintain link alignment. Simultaneously with the disturbance at the first terminal, the two light spots on the second terminal will also deviate. However, the control module of the second terminal calculates d=0 and θ=θ0 based on the light spot positions, where θ0 is the angle of the disturbance. The second terminal will not deflect. Thus, the disturbance at the first terminal will be compensated by the two-axis deflection mirror of the first terminal and will not affect the second terminal.

[0157] Similarly, when the second terminal generates a rotational disturbance of θ0, the light spot on the visible light camera of the first terminal deviates from the center, driving the deflection mirror of the first terminal to deflect. Simultaneously, the control module of the second terminal calculates d = L × θ0 and θ = θ0 based on the light spot position, and then controls the two-axis deflection mirror of its own terminal to rotate θ0 / 2. At this moment, the second terminal compensates for its own disturbance, and continues to point precisely at the first terminal. However, because the first terminal has performed additional rotational compensation for the disturbance of the second terminal, the pointing of the first terminal has an error. Then, through the same compensation process as when the first terminal has a disturbance, the first terminal cancels out this additional rotation. Thus, the disturbance of the second terminal, ultimately compensated by the second terminal, will not affect the first terminal. When both terminals have disturbances simultaneously, this process of first aligning the second terminal and then aligning the first terminal can maintain link alignment, achieving stable full-duplex communication indoors.

[0158] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0159] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0160] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0161] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0162] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An indoor laser wireless two-way communication system, characterized in that, include: The first terminal and the second terminal are equipped with a beam-combining transmission optical path and a beacon optical transmission optical path. A signal light collimator, a dichroic mirror, and a two-axis deflector are sequentially arranged on the beam-combining transmission optical path. A beacon light processing module and a dichroic mirror are provided on the beacon light transmission optical path; The beam combining transmission optical path intersects with the beacon light transmission optical path at a dichroic mirror; The signal light collimator is used to generate signal light and process the received signal light; The beacon light processing module is used to generate beacon light and acquire images of the received beacon light; The dichroic mirror is used to transmit signal light on the beam combining transmission optical path and to reflect beacon light between the two-axis deflection mirror on the beam combining transmission optical path and the beacon light processing module on the beacon light transmission optical path. The two-axis deflecting mirror is used to reflect signal light and beacon light between the beam combining transmission optical path and the input / output optical path of this terminal; The terminal is also equipped with a control module and a wide-angle camera; The control module is used to acquire environmental images through the wide-angle camera, analyze the position of another terminal in the environmental images and adjust the two-axis deflection mirror so that the optical axis of this terminal initially points to the other terminal, and analyze the position of the beacon light in the acquired beacon light image and adjust the two-axis deflection mirror so that the received beacon light coincides with the optical axis of this terminal. The beacon light processing module of the second terminal includes: a beam splitter, a retroreflection prism, a reflector, a focusing lens, and a visible light camera; Accordingly, the dichroic mirror, the beam splitter, and the retroreflection prism are sequentially arranged on the beacon light transmission optical path of the second terminal; Accordingly, the second terminal is also configured with a first beacon light receiving optical path and a second beacon light receiving optical path. The beam splitter, the lens and the visible light camera are sequentially arranged on the two beacon light receiving optical paths. A reflector is also arranged on the second beacon light receiving optical path. The reflector and the lens are arranged on both sides of the beam splitter. The beacon light transmission optical path, the first beacon light receiving optical path, and the second beacon light receiving optical path intersect at the beam splitter; The beam splitter of the second terminal is used to reflect the first beacon light between the dichroic mirror in the beacon light transmission optical path and the lens in the first beacon light receiving optical path, and to transmit the first beacon light to the retroreflection prism in the beacon light transmission optical path. The first beacon light is generated by the first terminal. The retroreflection prism is used to receive the first beacon light on the beacon light transmission optical path and reflect the received first beacon light along the beacon light transmission optical path to the beam splitter. The light reflected by the retroreflection prism serves as the second beacon light. The beam splitter of the second terminal is also used to reflect the second beacon light to the reflector and transmit the second beacon light to the dichroic mirror along the beacon light transmission path; The reflector is used to receive the second beacon light from the beam splitter and reflect the second beacon light back to the beam splitter along the receiving optical path of the second beacon light; The beam splitter of the second terminal is also used to receive the second beacon light from the reflector and transmit the second beacon light to the lens in the second beacon light receiving optical path.

2. The indoor laser wireless two-way communication system according to claim 1, characterized in that, The control module of the second terminal is used for: Determine a first distance x1 in the horizontal direction of the first light spot relative to the center of the visible light camera, and determine a second distance x2 in the horizontal direction of the second light spot relative to the center of the visible light camera; the first light spot is formed by the first beacon light on the image of the visible light camera at the second terminal, and the second light spot is formed by the second beacon light on the image of the visible light camera at the second terminal. Based on the first distance x1 and the second distance x2, a third distance d is determined between the emission point of the first beacon light and the optical axis of the second terminal; Based on the third distance d and the fourth distance L between the two ends, the angle to be deflected by the two-axis deflecting mirror is determined. .

3. The indoor laser wireless two-way communication system according to claim 2, characterized in that, The control module of the second terminal is also used to determine the third distance d using the following formula: ； ； Where f represents the focal length of the lens, c represents the distance between the image frame and the focal plane of the visible light camera, a represents the distance between the two-axis deflecting mirror at the second terminal and the dichroic mirror at the second terminal, b1 represents the distance from the beam splitter to the dichroic mirror, b2 represents the distance from the beam splitter to the retroreflection prism, b3 represents the distance from the beam splitter to the reflecting mirror, b4 represents the distance from the beam splitter to the lens, and θ represents the angle between the optical axes of the two terminals. It is determined based on the tilt angle of the reflector.

4. The indoor laser wireless two-way communication system according to claim 2, characterized in that, The control module of the second terminal is also used to determine the angle to be deflected using the following formula. : .

5. The indoor laser wireless two-way communication system according to claim 2, characterized in that, The control module of the second terminal is also used for: If d=0 and θ=θ0 are determined, then θ0 is determined to be the disturbance angle generated by the first terminal, and θ represents the angle between the optical axes of the two terminals; If d = L × θ0 and θ = θ0 is determined, then θ0 is determined to be the disturbance angle generated by the second terminal, and the two-axis deflection mirror of the second terminal is controlled to rotate θ0 / 2.

6. The indoor laser wireless two-way communication system according to claim 1, characterized in that, The beacon light processing module of the first terminal includes: a beacon light laser, a beam splitter, and a beacon light image acquisition module; Accordingly, the beacon laser, the beam splitter, and the dichroic mirror are sequentially arranged on the beacon light transmission optical path of the first terminal; Accordingly, the first terminal is also configured with a beacon light receiving optical path, and the beam splitter and the beacon light image acquisition module are provided on the beacon light receiving optical path of the first terminal; The beacon light transmission optical path and the beacon light receiving optical path of the first terminal intersect at the beam splitter; The beacon laser is used to generate the first beacon light; The beam splitter of the first terminal is used to transmit the first beacon light in the beacon light transmission optical path and reflect the second beacon light between the dichroic mirror in the beacon light transmission optical path and the beacon light image acquisition module in the beacon light receiving optical path. The second beacon light is reflected by the second terminal through the retroreflection prism. The beacon light image acquisition module is used to acquire images of the received second beacon light.

7. The indoor laser wireless two-way communication system according to claim 6, characterized in that, The beacon light image acquisition module includes a lens for focusing and a visible light camera, wherein the image frames of the two terminal visible light cameras are not located at the focal plane of the lens.

8. The indoor laser wireless two-way communication system according to claim 6, characterized in that, The control module of the first terminal is used for: Control the scanning of the two-axis deflection mirror; If it is determined that the second beacon light is fully received by the first terminal, the two-axis deflection mirror is controlled to deflect until the second beacon light is located at the center of the visible light camera's image, so that the received second beacon light coincides with the optical axis of the second terminal.

9. The indoor laser wireless two-way communication system according to any one of claims 1-8, characterized in that, The control module is used for: Based on the position of another terminal in the environmental image, determine the angle of the line connecting the other terminal and the wide-angle camera of this terminal relative to the optical axis of the wide-angle camera of this terminal. ; Based on angle The following formula is used to determine the angle to be deflected by the two-axis deflecting mirror. ; ； in, H represents the distance between the visible light camera and the two-axis deflection mirror, and H represents the height difference between the two ends.

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