Space dual-channel fiber optic rotary joint

Abstract

The present application relates to a fiber optic rotary joint, in particular to a space dual-channel fiber optic rotary joint, to solve the problem of poor environmental adaptability, high assembly difficulty or difficulty in completing bidirectional signal transmission of the existing dual-channel fiber optic rotary joint. The space dual-channel fiber optic rotary joint comprises a rotor sleeve, a stator shell, a first optical assembly and a second optical assembly, the rotor sleeve and the stator shell are coaxially connected, the first optical assembly comprises a first input assembly, a beam expanding assembly, a beam shrinking assembly and a first output assembly arranged in sequence along the optical path, the first input assembly and the beam expanding assembly are arranged in the rotor sleeve, input the first optical signal and form a collimated hollow beam; the beam shrinking assembly and the first output assembly are arranged in the stator shell, and the collimated hollow beam is shrunk and output; the second optical assembly is arranged in the second input assembly and the second output assembly in the stator shell, and is used for transmitting the second optical signal.

Description

TECHNICAL FIELD

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

[0002] The fiber optic rotary joint is an important optical device for signal transmission, which uses optical fiber as a transmission medium to realize the transmission of signals between a rotating platform and another static platform. The dual-channel fiber optic rotary joint can realize the simultaneous transmission of dual-channel signals, which is convenient for transmitting multiple signals and has the advantage of multiple transmission compared with the single-channel fiber optic rotary joint, and is convenient for providing a backup channel for signal transmission. The fiber optic rotary joint applied in the field of aerospace needs to have the characteristics of high reliability and long service life. At present, with the rapid development of aerospace industry, multi-channel fiber optic rotary joints have been widely applied and developed, especially dual-channel fiber optic rotary joints. The existing dual-channel fiber optic rotary joint often adopts Dove prism structure, mirror structure and lens structure.

[0003] The dual-channel fiber optic rotary joint adopting the Dove prism structure utilizes the light transmission principle of the Dove prism, and realizes 2:1 speed reduction through a gear transmission mechanism, which offsets the 1:2 rotation ratio of the Dove prism object image, thereby realizing the multi-channel signal transmission between the stator end and the rotor end. Since there is a mechanical structure, its adaptability in space environment is poor, and its reliability is low. Moreover, the environmental adaptability of the Dove prism is poor, and dew will appear on the surface of the Dove prism under humid and hot conditions, resulting in abnormal transmission of optical signals. The dual-channel fiber optic rotary joint adopting the mirror structure utilizes the mirror to realize the turning of the light beam, and after multiple reflections, the light beam enters the receiving end to complete the signal transmission. The structure can select a magnet or a gear as a support for the mirror. However, due to the existence of the mirror structure, the transmission path of the multi-channel light beam is relatively complex, and the assembly difficulty is high, which causes some light beams to be blocked, thereby increasing the insertion loss of the fiber optic rotary joint. At the same time, the magnet and gear structure will reduce the reliability of the fiber optic rotary joint, and the environmental adaptability is poor. The dual-channel fiber optic rotary joint adopting the lens structure uses a Fresnel lens or a spherical lens structure to construct a passive symmetric optical structure. Part of the optical devices at the transmitting end is placed off-axis, and the light beam is transmitted to the receiving end through the Fresnel lens or the spherical lens. However, the coupling light beam capacity of the receiving end in this structure is poor, and the machining and assembly precision requirements are high. Moreover, this structure is mainly used for one-way signal transmission, and it is difficult to complete bidirectional transmission. SUMMARY

[0004] The purpose of the present application is to solve the problems of poor environmental adaptability, high assembly difficulty or difficulty in completing bidirectional signal transmission of the existing dual-channel fiber optic rotary joint, and to provide a space dual-channel fiber optic rotary joint.

[0005] To achieve the above object, the technical solution provided by the application is as follows:

[0006] A space dual-channel optical fiber rotary connector comprises a rotor sleeve and a stator shell arranged at rotor end and stator end respectively, and the rotor sleeve and the stator shell are coaxially connected in rotation, and the special feature is that it further comprises a first optical assembly for transmitting a first optical signal and a second optical assembly for transmitting a second optical signal; the first optical assembly comprises a first input assembly, a beam expanding assembly, a beam shrinking assembly and a first output assembly arranged in sequence along an optical path; the first input assembly and the beam expanding assembly are arranged in the rotor sleeve, the first input assembly is used for coupling the first optical signal and adjusting it to be adapted to the diameter of the beam expanding assembly, and the beam expanding assembly is used for expanding and collimating the hollow light beam to form a collimated hollow light beam; the beam shrinking assembly and the first output assembly are arranged in the stator shell, and the collimated hollow light beam is coupled and output by the first output assembly after being shrunk by the beam shrinking assembly; the second optical assembly is arranged in the stator shell and comprises a second input assembly and a second output assembly arranged coaxially with the beam shrinking assembly, and is used for transmitting the second optical signal.

[0007] Further, the beam expanding assembly comprises a plano-concave lens and a plano-convex lens arranged coaxially in the rotor sleeve, the first input assembly comprises a first input optical fiber and a first graded-index lens, and the first input optical fiber is a photonic crystal optical fiber;

[0008] The convex surface of the plano-convex lens is arranged opposite to the concave surface of the plano-concave lens; a first through hole is formed in the center of the plano-concave lens, and the first graded-index lens is arranged in the first through hole;

[0009] One end of the first input optical fiber is connected to the incident end of the first graded-index lens and is used for conveying the first optical signal, and the other end is connected to an external emitting device; the first optical signal is conveyed to the first graded-index lens for beam expanding, and then is reflected by the plano-convex lens and the plano-concave lens in sequence to form a collimated hollow light beam.

[0010] Further, the beam expanding assembly comprises a plano-concave lens and a plano-convex lens arranged coaxially in the rotor sleeve, the first input assembly comprises a first input optical fiber and a first graded-index lens, and the first input optical fiber is a multi-mode optical fiber;

[0011] The convex surface of the plano-convex lens is arranged opposite to the concave surface of the plano-concave lens; a first through hole is formed in the center of the plano-concave lens, and the first graded-index lens is arranged in the first through hole;

[0012] One end of the first input optical fiber is connected to the incident end of the first graded-index lens and is used for conveying the first optical signal, and the other end is connected to an external emitting device;

[0013] The first graded-index lens and the plano-convex lens are further provided with an axicon lens group;

[0014] The first optical signal is transmitted by the first input optical fiber to the first graded-index lens for beam expansion, and then forms a hollow light beam through the axicon lens group, and then is reflected by the plano-convex lens and the plano-concave lens in sequence to form a collimated hollow light beam.

[0015] Further, the beam expansion assembly comprises a first meniscus lens, a second meniscus lens and a double-concave lens arranged in sequence along the light path, and the first output assembly comprises a second graded-index lens and a first output optical fiber;

[0016] The first meniscus lens is arranged on the reflection light path of the plano-concave lens, the concave surfaces of the first meniscus lens and the second meniscus lens face the plano-concave lens, and the second graded-index lens is located on the exit light path of the double-concave lens;

[0017] The exit end of the second graded-index lens is connected to one end of the first output optical fiber.

[0018] Further, the second input assembly comprises a first optical fiber collimator and a second input optical fiber, the input end of the first optical fiber collimator is connected to one end of the second input optical fiber for receiving the second optical signal;

[0019] The second output assembly comprises a second optical fiber collimator and a second output optical fiber, the input end of the second optical fiber collimator corresponds to the output end of the first optical fiber collimator, the output end is connected to one end of the second output optical fiber for outputting the second optical signal.

[0020] Further, the stator shell is provided with a first cavity and a second cavity in sequence and in communication;

[0021] The rotor sleeve is nested in the first cavity in the stator shell and is connected to the stator shell through a bearing assembly.

[0022] Further, the stator shell is a cylindrical structure, and a stator end cover is arranged at an end of the stator shell away from the first cavity;

[0023] The rotor sleeve is a cylindrical structure, and a rotor end cover is arranged at an end of the rotor sleeve away from the second cavity;

[0024] A second through hole is formed in the center of the rotor end cover, and the incident end of the first graded-index lens is nested in the second through hole;

[0025] A third through hole is formed in the center of the stator end cover, and the other end of the first output optical fiber passes through the third through hole.

[0026] Further, the first output optical fiber is a multi-mode optical fiber;

[0027] The second input optical fiber and the second output optical fiber are both single-mode optical fibers.

[0028] Advantages of the present application:

[0029] 1. The two signal transmission channels formed in the present application are coaxial transmission channels, reducing the assembly difficulty; the signals of the double channels can both realize bidirectional transmission, and the light beams of the outer channels cannot be blocked by the middle channel, solving the problem of light beam blocking in the process of multi-channel light beam coaxial transmission, reducing the insertion loss of the outer channels, and improving the overall performance of the optical fiber rotary connector.

[0030] 2. The present application does not have gear mechanisms, magnets and other mechanical transmission mechanisms, greatly reducing the assembly difficulty, effectively improving the service life of the optical fiber rotary connector, reducing the risk that the optical fiber rotary connector cannot work due to the failure of the mechanical transmission mechanism, and having the characteristics of high reliability and strong environmental adaptability in space environment.

[0031] 3. The present application expands the incident light beam of the Cassegrain beam expansion system through the first graded-index lens, expanding the local hollow light beam range. The Cassegrain beam expansion system has simple structure, reduces the radial size of the coaxial transmission double-channel optical fiber rotary connector, makes it convenient to be installed and combined with the conductive slip ring into an optoelectronic composite slip ring, and has more extensive use.

[0032] 4. The present application generates a hollow light beam through a photonic crystal fiber, reduces the requirement for the incident first signal light, and has wider application range. The hollow light beam is expanded through the first graded-index lens, so that the central aperture is increased, and then passes through the Cassegrain beam expansion system again, so that the light spot and the central aperture are both expanded, greatly reducing the blocking of the central channel to the light beam of the outer channel.

[0033] 5. The space double-channel optical fiber rotary connector adopts high-precision self-lubricating ceramic ball bearings, ensuring the stability and reliability of optical signal transmission, and having long service life characteristics; the ceramic ball bearings are selected from materials with small ion radiation influence and low condensable volatile substances, ensuring the radiation resistance and low pollution of the optical fiber rotary connector, and having good space adaptability. Meanwhile, the space double-channel optical fiber rotary connector can also be applied to the fields of radar or medical treatment.

[0034] 6. The structure of the present application is passively arranged, has strong anti-electromagnetic interference energy, and can be used in special or extreme environments. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a structural schematic diagram of an embodiment of the present application;

[0036] Explanation of reference signs:

[0037] 1-first input optical fiber, 2-plano-concave lens, 3-first gradient-index lens, 4-plano-convex lens, 5-first meniscus lens, 6-second meniscus lens, 7-biconcave lens, 8-second gradient-index lens, 9-first optical fiber collimator, 10-second optical fiber collimator, 11-second output optical fiber, 12-second input optical fiber, 13-stator housing, 14-ceramic ball bearing, 15-washer, 16-rotor sleeve, 17-rotor end cover, 18-support rod, 19-stator end cover, 20-first output optical fiber. DETAILED DESCRIPTION

[0038] The present invention provides a space dual-channel optical fiber rotary connector such as Figure 1 As shown, it includes a first optical component for transmitting a first optical signal and a second optical component for transmitting a second optical signal, as well as a rotor sleeve 16 arranged at the rotor end and a stator housing 13 arranged at the stator end.

[0039] The stator housing 13 and the rotor sleeve 16 are both cylindrical structures. A first cavity and a second cavity are sequentially provided in the stator housing 13. A stator end cover 19 is provided at the end of the stator housing 13 away from the first cavity. The rotor sleeve 16 is nested in the stator housing 13 and located in the first cavity. It is connected to the stator housing 13 through a bearing assembly. A rotor end cover 17 is provided at the end of the rotor sleeve 16 away from the second cavity. Figure 1 As shown, the bearing assembly primarily consists of a ceramic ball bearing 14, a washer 15, and a retainer. It is a key component for ensuring signal transmission and longevity. In this invention, the bearing assembly utilizes non-metallic materials with low mass loss and low condensable volatiles, reducing the contamination effects of condensable volatiles on the optical system. The bearing utilizes a self-lubricating ceramic ball bearing 14, and the bearing retainer utilizes a polyimide material, significantly improving service life from both material and structural perspectives. Furthermore, both the first and second optical assemblies utilize radiation-resistant optical glass, effectively preventing the effects of space particle radiation.

[0040] The first optical assembly comprises a first input assembly, a beam expander assembly, a beam reducer assembly and a first output assembly arranged in sequence along the optical axis, the first input assembly comprises a first input optical fiber 1 and a first graded index lens 3, the incident end of the first graded index lens 3 is connected to one end of the first input optical fiber 1, the first input optical fiber 1 is a photonic crystal fiber, the other end is connected to an external optical signal transmitting device, used for receiving an optical signal and converting it into a hollow light beam, the first graded index lens 3 expands the hollow light beam by the graded refractive index, the beam expander assembly comprises a plano-convex lens 4 and a plano-concave lens 2 arranged in a rotor sleeve 16 along the optical path, the plano-convex lens 4 is fixed in the rotor sleeve 16 by a support rod 18, the convex surface of the plano-convex lens 4 is arranged opposite to the concave surface of the plano-concave lens 2, the plano-concave lens 2 is arranged close to a rotor end cover 17, the plano-concave lens 2 is provided with a first through hole along the central axis, the rotor end cover 17 is provided with a second through hole at the center, the first graded index lens 3 is arranged in the first through hole and the incident end is embedded in the second through hole. The expanded hollow light beam is reflected by the plano-convex lens 4 and the plano-concave lens 2 in sequence to further expand and form a collimated hollow light beam.

[0041] The plano-concave lens 2 and the plano-convex lens 4 form a Cassegrain beam expander system, the Cassegrain beam expander system has a simple and compact structure, can reduce the dispersion of the light beam transmission and improve the coupling efficiency of the collimated hollow light beam, at the same time, the aperture size of the expanded hollow light beam can be adjusted according to the refractive index distribution and length of the first graded index lens 3, thereby reducing the occlusion of the Cassegrain beam expander system to the light beam.

[0042] The beam reducer assembly is arranged in a second cavity of the stator housing 13 and comprises a first meniscus lens 5, a second meniscus lens 6 and a double concave lens 7 arranged in sequence along the optical path, the first output assembly is arranged at one end of the second cavity away from the first cavity and comprises a second graded index lens 8 and a first output optical fiber 20.

[0043] The first meniscus lens 5 is arranged on the reflection path of the plano-concave lens 2, the concave surfaces of the first meniscus lens 5 and the second meniscus lens 6 face the plano-concave lens 2, the second graded index lens 8 is located on the exit light path of the double concave lens 7 and at one end of the second cavity, the exit end of the second graded index lens 8 is connected to one end of the first output optical fiber 20, the stator housing 13 is provided with a stator end cover 19 at the end of one end of the second cavity to realize the sealing of the stator housing 13, the center of the stator end cover 19 is provided with a third through hole, the other end of the first output optical fiber 20 passes through the third through hole and is arranged for connecting an external optical signal receiving device, in the embodiment, the first output optical fiber 20 is a multi-mode optical fiber. The collimated hollow light beam passes through the beam reducer assembly composed of the first meniscus lens 5, the second meniscus lens 6 and the double concave lens 7 to realize beam reduction and collimation, then is incident into the graded index lens and is coupled to the first output optical fiber 20 for output.

[0044] The first meniscus lens 5 and the second meniscus lens 6 are arranged at the stator end, so that the collimated hollow light beam reaches the stator end and then is shrunk, the position error of the first meniscus lens 5 and the second meniscus lens 6 in the rotating process is reduced, and the influence of the position error on the shrinking of the light beam is reduced, and the optical axis, the central axis of the stator shell 13 and the central axis of the rotor sleeve 16 are coincident. By selecting the refractive index distribution of the second graded refractive index lens 8 and designing the length thereof, the collimated hollow light beam after shrinking can be coupled into the optical fiber with high efficiency, and the structure is simple, the cost is low, and the coupling efficiency is high.

[0045] The second optical assembly is arranged at the stator end and comprises the first optical fiber collimator 9 and the second optical fiber collimator 10 arranged in sequence along the light path, the input end of the first optical fiber collimator 9 is connected to one end of the second input optical fiber 12, the second optical signal is input through the second input optical fiber 12, the output end of the second optical fiber collimator 10 is connected to one end of the second output optical fiber 11, and the second optical signal is output through the second output optical fiber 11, and the second input optical fiber 12 and the second output optical fiber 11 are both single-mode optical fibers. The first optical fiber collimator 9 and the second input optical fiber 12 constitute a second input assembly, and the second optical fiber collimator 10 and the second output optical fiber 11 constitute a second output assembly.

[0046] The first meniscus lens 5 and the second meniscus lens 6 are respectively provided with mounting holes along the central axis, and the first optical fiber collimator 9 and the second optical fiber collimator 10 are arranged in the mounting holes of the first meniscus lens 5 and the second meniscus lens 6. The second optical signal is transmitted to the first optical fiber collimator 9 through the second input optical fiber 12, is collimated, and then is coupled to the second output optical fiber 11 through the second optical fiber collimator 10, so that the optical signal transmission is realized.

[0047] In other embodiments of the application, the first input optical fiber 1 can also be a multi-mode optical fiber, the first optical signal is input, is expanded through the first graded refractive index lens 3, generates a hollow light beam through the axicon lens group, and then is expanded through the plano-convex lens 4 and the plano-concave lens 2. Meanwhile, other transmission type expansion systems can also be used to realize expansion.

Claims

1. A spatial dual-channel optical fiber rotary joint comprising a rotor sleeve (16) and a stator housing (13) arranged at rotor end and stator end respectively, the rotor sleeve (16) and the stator housing (13) are coaxially connected, characterized in that: it further comprises a first optical assembly for transmitting a first optical signal and a second optical assembly for transmitting a second optical signal; the first optical assembly comprises a first input assembly, a beam expanding assembly, a beam shrinking assembly and a first output assembly arranged in sequence along an optical path; the first input assembly and the beam expanding assembly are arranged in the rotor sleeve (16), the first input assembly is used for coupling the first optical signal and adjusting it to be adapted to the diameter of the beam expanding assembly, the beam expanding assembly is used for expanding and collimating the hollow beam to form a collimated hollow beam; the beam expanding assembly comprises a plano-concave lens (2) and a plano-convex lens (4) arranged coaxially in the rotor sleeve (16), and the first input assembly comprises a first input fiber (1) and a first graded index lens (3); the plano-concave lens (2) has a first through hole in the center, and the first graded index lens (3) is arranged in the first through hole; one end of the first input fiber (1) is connected to the incident end of the first graded index lens (3) for transmitting the first optical signal, and the other end is connected to an external emitting device; the first input fiber (1) is a photonic crystal fiber; the first optical signal is transmitted by the first input fiber (1) to the first graded index lens (3) for beam expansion, and then reflected by the plano-convex lens (4) and the plano-concave lens (2) in sequence to form a collimated hollow beam; alternatively, the first input fiber (1) is a multi-mode fiber; an axicon lens group is further arranged between the first graded index lens (3) and the plano-convex lens (4); the first optical signal is transmitted by the first input fiber (1) to the first graded index lens (3) for beam expansion, then forms a hollow beam through the axicon lens group, and then reflected by the plano-convex lens (4) and the plano-concave lens (2) in sequence to form a collimated hollow beam; the beam shrinking assembly and the first output assembly are arranged in the stator housing (13), and the collimated hollow beam is shrunk by the beam shrinking assembly and then coupled and output by the first output assembly; the second optical assembly is arranged in the stator housing (13) and comprises a second input assembly and a second output assembly arranged coaxially with the beam shrinking assembly for transmitting a second optical signal. 2.The spatial dual-channel optical fiber rotary joint according to claim 1, characterized in that: the convex surface of the plano-convex lens (4) is arranged opposite to the concave surface of the plano-concave lens (2). 3.The spatial dual-channel optical fiber rotary joint according to claim 2, characterized in that: the beam shrinking assembly comprises a first meniscus lens (5), a second meniscus lens (6) and a double-concave lens (7) arranged in sequence along an optical path, and the first output assembly comprises a second graded index lens (8) and a first output fiber (20). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The first meniscus lens (5) is arranged on the reflected light path of the plano-concave lens (2), the concave surface of the first meniscus lens (5) and the second meniscus lens (6) faces the plano-concave lens (2), and the second graded-index lens (8) is arranged on the outgoing light path of the biconcave lens (7); The outgoing end of the second graded-index lens (8) is connected to one end of the first output optical fiber (20).

4. The spatial dual-channel optical fiber rotary joint according to claim 3, characterized in that: The second input assembly comprises a first optical fiber collimator (9) and a second input optical fiber (12), the input end of the first optical fiber collimator (9) is connected to one end of the second input optical fiber (12) for receiving the second optical signal; The second output assembly comprises a second optical fiber collimator (10) and a second output optical fiber (11), the input end of the second optical fiber collimator (10) corresponds to the output end of the first optical fiber collimator (9), and the output end is connected to one end of the second output optical fiber (11) for outputting the second optical signal.

5. The spatial dual-channel optical fiber rotary joint according to claim 4, characterized in that: The first cavity and the second cavity are sequentially arranged in the stator housing (13) and are in communication; The rotor sleeve (16) is nested in the first cavity in the stator housing (13) and is connected to the stator housing (13) through a bearing assembly.

6. The spatial dual-channel optical fiber rotary joint according to claim 5, characterized in that: The stator housing (13) is a cylindrical structure, and a stator end cover (19) is arranged at the end of the stator housing (13) away from the first cavity; The rotor sleeve (16) is a cylindrical structure, and a rotor end cover (17) is arranged at the end of the rotor sleeve (16) away from the second cavity; A second through hole is formed in the center of the rotor end cover (17), and the incident end of the first graded-index lens (3) is nested in the second through hole; A third through hole is formed in the center of the stator end cover (19), and the other end of the first output optical fiber (20) passes through the third through hole.

7. The spatial dual-channel optical fiber rotary joint according to claim 6, characterized in that: The first output optical fiber (20) is a multi-mode optical fiber; The second input optical fiber (12) and the second output optical fiber (11) are both single-mode optical fibers.

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