Space off-axis dual-channel fiber optic rotary joint

Abstract

The present application relates to a fiber optic rotary joint, in particular to a spatial off-axis double-channel fiber optic rotary joint, to solve the problem of high machining and assembling precision, large loss, and unstable transmission stability and efficiency in the prior art. The spatial off-axis double-channel fiber optic rotary joint comprises a rotor sleeve, a first collimating lens, a second collimating lens, and a plano-convex lens arranged in the rotor sleeve, a stator housing, a first lens, a second lens, a flat glass, a first meniscus lens, a second meniscus lens, a second self-focusing lens, and a first self-focusing lens arranged in the stator housing, the first lens and the second lens are respectively provided with a concave surface along the central axis, and are used for shaping and transmitting the laser beam transmitted by the first collimating lens to the first self-focusing lens; the first meniscus lens and the second meniscus lens are used for transmitting the second laser beam input by the second collimating lens.

Description

TECHNICAL FIELD

[0001] The present application relates to a fiber optic rotary joint, in particular to a space off-axis dual-channel fiber optic rotary joint. BACKGROUND

[0002] The fiber optic rotary joint, also known as a fiber optic slip ring, is an optical communication device that enables stable transmission of optical signals in a rotating state. It effectively solves the problem of signal transmission between rotating and stationary parts, and has the advantages of large channel capacity, strong anti-electromagnetic interference ability, no contact loss, and fast transmission rate. Through precise design, the internal optical fibers can maintain good alignment and coupling during relative rotation, ensuring low-loss and high-reliability transmission of optical signals. Therefore, the fiber optic rotary joint has a wide range of application scenarios in many fields. In radar systems, it is used for signal transmission between rotating and stationary platforms, ensuring stable data transmission during radar rotation scanning. In industrial automation, it can achieve accurate transmission of control signals and feedback signals during robot joint movement, ensuring precise robot operation. In aerospace, it can complete high-speed and large-capacity data interaction between rotating parts of space motion mechanisms in complex space environments and motion states. In medical devices, it meets the high-bandwidth, low-loss, and anti-interference signal transmission requirements of rotating scanning devices and rotating communication equipment in marine vessels.

[0003] Existing rotary joints are mostly coaxial, with signal transmission channels coinciding with the central axis. When the central axis is occupied, signal transmission is not possible, and off-axis fiber optic rotary joints are needed at this time. Compared with coaxial fiber optic rotary joints, off-axis fiber optic rotary joints can solve the problem of optical signal transmission when the central axis is occupied by other media or devices.

[0004] Chinese patent publication number CN108710177A discloses a novel off-axis fiber optic rotary connector system comprising a signal input unit, a rotary connection unit, and a signal output unit. The signal input unit transmits optical signals to the rotary connection unit via multiple circular input channels and a fiber collimator. Within the rotary connection unit, an annular grating deflects light into an annular base. Its conical reflective film ensures signal reflection and transmission, while a light shielding tube provides light shielding. A fixed rubber ring stabilizes the components, and the signal is emitted from the output window after multiple reflections. The signal output unit couples the optical signal through a lens system corresponding to the receiving channel, outputs it through a fiber collimator, and can also collect data. This system, based on wavelength division multiplexing, solves the problem of central axis occupancy. It features a simple structure, easy fabrication, excellent stability, and high coupling efficiency. It holds great promise in the fields of spatial optical interconnection and fiber optic communications, providing a reliable solution for optical communication signal transmission. This method can achieve directional transmission of off-axis optical beams in relative rotational motion. However, since it utilizes reflection of the beam within the annular base to achieve beam transmission, it requires high precision machining and assembly of structural components, resulting in significant losses during transmission. At the same time, under some extreme environmental conditions, the annular grating and annular substrate used may not be able to maintain long-term stable operation, reducing the reliability of the system.

[0005] The Chinese patent with publication number CN115166909A discloses an off-axis fiber optic rotary connector based on a double collimating lens and a TEC fiber. It uses four double collimating lens systems evenly distributed 360 degrees as rotors, which are combined with the stator of the double collimating lens system to achieve multi-signal transmission through relative motion processes such as separation, tangency, and intersection. In this method, there are internal threaded holes at both ends of the hollow rotating shaft disk, which are adapted to fit scaled studs to assemble rotating hollow shafts with different shaft diameters. This method realizes signal transmission under different shaft diameter conditions, and uses a combination of TEC fiber and a double collimating lens system to increase alignment time and beam transmission efficiency, effectively avoiding the problem of the center axis being occupied. However, its transmission power is unstable, and the consistency of the optical-mechanical structure assembly is required to be high. When the fiber optic patch cord used is a single-mode fiber, the beam transmission efficiency will be greatly reduced, which is not conducive to optical signal transmission.

[0006] Chinese patent publication number CN110361814A proposes a multi-channel off-axis fiber optic rotary connector using a hollow annular cone. This method utilizes the cone's surface reflection to couple the optical beam signal at the rotor end to the transmission fiber at the stator end. This method can simultaneously transmit multiple signals and boasts high coupling efficiency, a simple structure, good stability, and no signal crosstalk. However, the transmission efficiency of this method is significantly affected by the machining and alignment accuracy of the hollow annular cone. Furthermore, the rotor's rotational speed significantly affects the stability of signal transmission.

[0007] A kind of off-axis optical fiber rotary connector based on right-angle prism is proposed in Chinese patent with publication number CN103149642A.This method utilizes right-angle prism to realize collimated beam turning, while changing the number of flange at light input / output, thereby affecting the rotation fluctuation of insertion loss, it adopts passive device, installation is convenient, greatly reduces the sensitivity of angle and axial deviation, reduces system insertion loss, can realize bidirectional transmission, but transmission fluctuation is larger. SUMMARY

[0008] The purpose of the present application is to solve the problems of high machining and assembling precision, large loss or transmission stability and efficiency in prior art, and to provide a space off-axis double-channel optical fiber rotary connector.

[0009] To achieve the above-mentioned purpose, the technical solution provided by the present application is as follows:

[0010] A space off-axis double-channel optical fiber rotary connector, comprising a rotor end and a stator end, characterized in that: the rotor end comprises a rotor sleeve and a first collimating lens, a second collimating lens and a plano-convex lens arranged in the rotor sleeve, the stator end comprises a stator housing and a first lens, a second lens, a flat glass, a first meniscus lens, a second meniscus lens, a second self-focusing lens arranged in the stator housing in sequence, and a first self-focusing lens arranged on the flat glass; one end of the rotor sleeve and the stator housing is coaxially connected; the input ends of the first collimating lens and the second collimating lens are connected with a first input optical fiber and a second input optical fiber respectively, and are used for collimating a first laser beam input by the first input optical fiber and a second laser beam input by the second input optical fiber respectively, the output end of the first collimating lens corresponds to the edge position of the convex surface of the plano-convex lens, and the output end of the second collimating lens corresponds to the position close to the central axis; the first lens is arranged at one end of the stator housing, the end faces of the two ends of the first lens are arranged as a first flat surface part close to the edge position and a first concave surface part close to the central axis respectively, the end face close to one end of the second lens is a flat surface, the other end face is arranged as a second flat surface part corresponding to the first flat surface part and a second concave surface part corresponding to the first concave surface part; the collimated first laser beam is shaped and transmitted to the first meniscus lens through the plano-convex lens, the first flat surface part, the second flat surface part and the flat glass, and the collimated second laser beam is shaped and transmitted to the first self-focusing lens through the plano-convex lens, the first concave surface part and the second concave surface part; the concave surfaces of the first meniscus lens and the second meniscus lens face the second self-focusing lens, for transmitting the first laser beam to the second self-focusing lens; the output ends of the second self-focusing lens and the first self-focusing lens are connected with a first output optical fiber and a second output optical fiber respectively.

[0011] Further, the rotor sleeve is embedded in one end of the stator shell; one end of the rotor sleeve is embedded with a rotor end cover, two through holes are opened on the rotor end cover for setting the first collimating lens and the second collimating lens; the other end of the rotor sleeve is an open end, and the first lens is arranged towards the open end.

[0012] Further, the other end of the stator shell is provided with a stator end cover, and the stator end cover is fixedly connected with the stator shell through screws; a through hole is opened on the stator end cover for setting the first output optical fiber;

[0013] The side wall of the stator shell is provided with a through hole for setting the second output optical fiber.

[0014] Further, the flat plate glass is provided with a through hole along the central axis, and the first self-focusing lens is arranged in the through hole of the flat plate glass.

[0015] Further, the first collimating lens and the second collimating lens are both self-focusing lenses.

[0016] Further, the first input optical fiber and the second input optical fiber are multi-mode optical fibers or thermal expansion core optical fibers or large core optical fibers.

[0017] The first output optical fiber and the second output optical fiber are both multi-mode optical fibers.

[0018] Further, the outer side wall of the rotor sleeve and the inner side wall of the stator shell are rotatably connected through a bearing.

[0019] The plano-convex lens, the first lens, the second lens, the flat plate glass, the first meniscus lens and the second meniscus lens are fixedly connected with the rotor sleeve or the stator shell through a compression ring respectively.

[0020] The beneficial effects of the present application are:

[0021] 1. The present application considers the off-axis double-channel laser beam transmission in the rotating state from the system level, the rotor end structure is simple, and it is convenient to connect the rotating part of the motion mechanism, the off-axis double-channel is set to realize the signal transmission between the relative rotating mechanism, and the multi-channel signal transmission problem when the central channel cannot be transmitted is solved. The present application utilizes the plane part of the first lens and the plane part of the second lens, and the concave part of the first lens and the concave part of the second lens, respectively, to realize the modulation of the transmission beams of different channels, to improve the coupling efficiency of different channel beams and to reduce the transmission loss.

[0022] 2. The double-channel beam transmission in the present application does not exist the shielding phenomenon, effectively reduces the transmission process loss, reduces the signal attenuation and distortion phenomenon, and helps to improve the beam transmission efficiency. At the same time, the external channel and the internal channel share different parts of the same lens, so that the overall structure is compact.

[0023] 3. The receiving end of the application adopts a self-focusing lens and a multi-mode optical fiber, which improves the light beam coupling efficiency. At the same time, it is convenient to use the broadband light beam transmission in the wavelength division multiplexing technology, and the transmission bandwidth and transmission capacity are improved.

[0024] 4. The application adopts an all-optical link design, has good anti-electromagnetic interference ability, simplifies the structure setting of the rotor end, and has stronger environmental adaptability, and is suitable for complex space environment.

[0025] 5. The application adopts a transmission form without mechanical transmission structure, the structure setting is simple, there is no mechanical contact and friction wear physical process, has the advantages of high reliability, long service life and simple maintenance, especially in the application field with strict requirements on weight, stability and environmental adaptability. At the same time, it can realize multi-channel signal high-speed, large-capacity, high-bandwidth stable transmission in off-axis state, improve the adaptability and service life of the system under space conditions. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of an embodiment of the application;

[0027] MARKED FOR EXPLANATION:

[0028] 1-rotor sleeve, 2-stator shell, 3-bearing, 4-separation ring, 5-flat convex lens, 6-first lens, 7-first input optical fiber, 8-second lens, 9-flat glass, 10-first meniscus lens, 11-second meniscus lens, 12-screw, 13-stator end cover, 14-pressing ring, 15-first self-focusing lens, 16-multi-mode optical fiber, 17-second self-focusing lens, 18-rotor end cover, 19-first collimating lens, 20-second collimating lens, 21-second input optical fiber. DETAILED DESCRIPTION

[0029] The structure of the space off-axis double-channel optical fiber rotary connector of the application is shown in Figure 1 The structure of the space off-axis double-channel optical fiber rotary connector of the application is shown in

[0030] The outer side wall of the rotor sleeve 1 is provided with an annular mounting groove, and bearings 3 are arranged at both ends of the mounting groove respectively, so as to be connected with the inner side wall of the stator shell 2 through the bearings 3 to realize rotary connection. A partition ring 4 is arranged between the bearings 3 at both ends of the mounting groove, so as to limit the relative positions of the bearings 3. One end of the rotor sleeve 1 is embedded with a rotor end cover 18, and two through holes are formed in the rotor end cover 18, which are used for arranging a first collimating lens 19 and a second collimating lens 20 respectively. The other end of the rotor sleeve 1 is arranged as an open end and faces the first lens 6.

[0031] The input ends of the first collimating lens 19 and the second collimating lens 20 are connected with a first input optical fiber 7 and a second input optical fiber 21 respectively, so as to collimate the first laser beam input by the first input optical fiber 7 and the second laser beam input by the second input optical fiber 21 respectively. The output end of the first collimating lens 19 corresponds to the edge position of the convex surface of the plano-convex lens 5, and the output end of the second collimating lens 20 corresponds to the position close to the central axis. In the embodiment, the first collimating lens 19 and the second collimating lens 20 are both self-focusing lenses, and in other embodiments of the application, other collimating assemblies or collimating lenses can also be arranged. The first input optical fiber 7 and the second input optical fiber 21 can be arranged as a multimode fiber or a TEC fiber with a thermally expandable core or a large-core fiber.

[0032] The first lens 6 is arranged at one end of the stator shell 2. The end faces of the first lens 6 are arranged as a first flat surface portion close to the edge position and a first concave surface portion close to the central axis. The end face of the second lens 8 close to the first lens 6 is a flat surface, and the other end face is arranged as a second flat surface portion corresponding to the first flat surface portion and a second concave surface portion corresponding to the first concave surface portion. The concave surfaces of the first meniscus lens 10 and the second meniscus lens 11 face the second self-focusing lens 17, so as to transmit the first laser beam to the second self-focusing lens 17. The output ends of the second self-focusing lens 17 and the first self-focusing lens 15 are connected with a first output optical fiber and a second output optical fiber respectively, which are both used for beam shrinking and coupling of the laser beam. The first output optical fiber and the second output optical fiber are both arranged as a multimode fiber 16.

[0033] The other end of the stator shell 2 is provided with a stator end cover 13, and the stator end cover 13 is fixedly connected with the stator shell 2 through screws 12. A through hole is formed in the stator end cover 13, and the first output optical fiber passes through the through hole to connect with an external device. A through hole is also formed in the side wall of the stator shell 2, and the second output optical fiber passes through the through hole to connect with an external device.

[0034] In order to make the overall structure more compact, a through hole is formed in the flat glass 9 along the central axis, and the first self-focusing lens 15 is arranged in the through hole of the flat glass 9.

[0035] The double-channel laser beam transmission path of the application is specifically as follows: the first laser beam of the double-channel laser beam is incident to the first collimating lens 19 after the first input optical fiber 7, expanded and collimated, then shaped and transmitted by the plano-convex lens 5, the first flat surface of the first lens 6, the second flat surface of the second lens 8, the flat glass 9, the first meniscus lens 10, the second meniscus lens 11, and then transmitted to the second self-focusing lens 17, coupled into the multi-mode optical fiber 16 and output. The other laser beam is incident to the second collimating lens 20 after the second input optical fiber 21, expanded and collimated, then shaped and transmitted by the plano-convex lens 5, the first concave surface of the first lens 6, the second concave surface of the second lens 8, transmitted to the first self-focusing lens 15, and coupled into the multi-mode optical fiber 16 and output. The above type of lens structure cooperation can realize the spatial off-axis double-channel fiber rotary connector, wherein the curvature radius, thickness, spacing and material parameters of each lens are set according to the laser signal requirements or structural size requirements.

Claims

1. A spatial off-axis dual-channel optical fiber rotary connector comprising a rotor end and a stator end, characterized in that: the rotor end comprises a rotor sleeve (1) and a first collimating lens (19), a second collimating lens (20) and a plano-convex lens (5) arranged in the rotor sleeve (1), and the stator end comprises a stator housing (2) and a first lens (6), a second lens (8), a flat glass (9), a first meniscus lens (10), a second meniscus lens (11), a second self-focusing lens (17) and a first self-focusing lens (15) arranged in the stator housing (2) in sequence, and the first self-focusing lens (15) is arranged on the flat glass (9); one end of the rotor sleeve (1) and the stator housing (2) are coaxially connected; the input ends of the first collimating lens (19) and the second collimating lens (20) are connected with a first input optical fiber (7) and a second input optical fiber (21) respectively, and are used for collimating a first laser beam input by the first input optical fiber (7) and a second laser beam input by the second input optical fiber (21) respectively, and the output ends of the first collimating lens (19) and the second collimating lens (20) correspond to the edge position and the position close to the central axis of the convex surface of the plano-convex lens (5) respectively; the first lens (6) is arranged at one end of the stator housing (2), the two end faces of the first lens (6) are arranged as a first flat surface part close to the edge position and a first concave surface part close to the central axis respectively, the end face close to one end of the second lens (8) is a flat surface, the other end face is arranged as a second flat surface part corresponding to the first flat surface part and a second concave surface part corresponding to the first concave surface part; the collimated first laser beam is shaped and transmitted to the first meniscus lens (10) through the plano-convex lens (5), the first flat surface part, the second flat surface part and the flat glass (9), and the collimated second laser beam is shaped and transmitted to the first self-focusing lens (15) through the plano-convex lens (5), the first concave surface part and the second concave surface part; the concave surfaces of the first meniscus lens (10) and the second meniscus lens (11) face the second self-focusing lens (17), and are used for transmitting the first laser beam to the second self-focusing lens (17); the output ends of the second self-focusing lens (17) and the first self-focusing lens (15) are connected with a first output optical fiber and a second output optical fiber respectively.

2. The spatial off-axis dual-channel optical fiber rotary connector according to claim 1, characterized in that: the rotor sleeve (1) is embedded at one end of the stator housing (2); one end of the rotor sleeve (1) is embedded with a rotor end cover (18), two through holes are formed in the rotor end cover (18) and are used for arranging the first collimating lens (19) and the second collimating lens (20) respectively; the other end of the rotor sleeve (1) is an open end and faces the first lens (6).

3. The spatial off-axis dual-channel optical fiber rotary connector according to claim 2, characterized in that: ​ Another end of the stator shell (2) is provided with a stator end cover (13), the stator end cover (13) is fixedly connected with the stator shell (2) through a screw (12), a through hole is formed in the stator end cover (13) for arranging a first output optical fiber; A through hole is formed in the side wall of the stator shell (2) for arranging a second output optical fiber.

4. The spatial off-axis double-channel optical fiber rotary joint according to any one of claims 1-3, characterized in that: The flat glass (9) is provided with a through hole along the central axis, and the first self-focusing lens (15) is arranged in the through hole of the flat glass (9).

5. The spatial off-axis double-channel optical fiber rotary joint according to claim 4, characterized in that: The first collimating lens (19) and the second collimating lens (20) are both self-focusing lenses.

6. The spatial off-axis double-channel optical fiber rotary joint according to claim 5, characterized in that: The first input optical fiber (7) and the second input optical fiber (21) are both multi-mode optical fibers or thermal expansion core optical fibers or large core optical fibers; The first output optical fiber and the second output optical fiber are both multi-mode optical fibers (16).

7. The spatial off-axis double-channel optical fiber rotary joint according to claim 6, characterized in that: The outer side wall of the rotor sleeve (1) and the inner side wall of the stator shell (2) are rotatably connected through a bearing (3); The plano-convex lens (5), the first lens (6), the second lens (8), the flat glass (9), the first meniscus lens (10) and the second meniscus lens (11) are respectively fixedly connected with the rotor sleeve (1) or the stator shell (2) through a compression ring (14).

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