A T-shaped small fiber optic gyroscope

Abstract

The present invention relates to the technical field of fiber optic gyroscopes, and discloses a small fiber optic gyroscope with a T-shaped structure, comprising a light source, a coupler, a Y waveguide, a housing, a magnetic shielding sleeve, a polarization-maintaining fiber ring and a bracket; the magnetic shielding sleeve and the upper cap are relatively arranged on the housing, and the axial directions of the two are vertically distributed, the polarization-maintaining fiber ring is arranged in the magnetic shielding sleeve, and the bracket is arranged in the upper cap; the light source, the coupler and the Y waveguide are arranged on the bracket in sequence, and the three are respectively distributed along the axial direction of the upper cap; the detector is arranged on the detector circuit board, and the two are installed on the bracket and located in the housing; the coupler is respectively connected to the light source, the photodiode detector and the Y waveguide, and the Y waveguide is connected to the polarization-maintaining fiber ring. The present invention reduces the influence of the Shupe effect on the performance of the fiber optic gyroscope, and also effectively reduces the influence of the Farady effect on the performance of the fiber optic gyroscope, the overall structure is compact, the volume is small, and the stability and precision of the fiber optic gyroscope are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic gyroscopes, and more specifically, to a small fiber optic gyroscope with a T-shaped structure. Background Art

[0002] Fiber optic gyroscope is a high-precision inertial device based on the Sagnac effect, used to measure the angular velocity of the carrier. It has the characteristics of long life, small size, light weight, large measurement range, wide accuracy range, no moving parts, etc. It is widely used in aerospace, missile guidance and other fields. Since the ambient temperature, external magnetic field, and internal stress of the fiber optic ring will have a great impact on the fiber optic ring, the sensitive element in the fiber optic gyroscope, the non-reciprocal phase shift caused by the Shupe effect and the Farady effect will be superimposed on the Sagnac phase shift caused by the rotation of the carrier, thereby affecting the accuracy of the fiber optic gyroscope.

[0003] Therefore, it is crucial to arrange all devices reasonably in a limited space, increase space utilization, and ensure that the designed structure is conducive to device heat dissipation and shielding of external magnetic fields. The sensitive axis of the original cylindrical small fiber optic gyroscope is parallel to the axis of the cylinder. In actual use, due to the limitation of the installation surface, the required measurement direction is inconsistent with the sensitive axis of the fiber optic gyroscope, affecting the measurement accuracy. Summary of the invention

[0004] The purpose of the present invention is to provide a small fiber optic gyroscope with a T-shaped structure in view of the technical problems existing in the prior art. The overall structure is compact and the volume is small, and the stability and precision of the fiber optic gyroscope are improved.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is:

[0006] The present invention provides a small optical fiber gyroscope with a T-shaped structure, comprising a light source, a coupler, a Y waveguide, a housing, a magnetic shielding sleeve, a polarization-maintaining optical fiber ring and a bracket;

[0007] The magnetic shielding sleeve and the upper cap are relatively arranged on the outer shell, and the axial directions of the two are vertically distributed. The surface of the magnetic shielding sleeve is connected to the outer shell, and the end face of one end of the upper cap is connected to the outer shell; a polarization-maintaining fiber ring is arranged in the magnetic shielding sleeve, and a bracket is arranged in the upper cap, and a light source, a Y waveguide and a coupler are arranged on the bracket in sequence; the Y waveguide is located between the light source and the coupler, and the three are distributed along the axial direction of the upper cap respectively; the detector is arranged on the detector circuit board, and the two are installed on the bracket and located in the outer shell; the coupler is connected to the light source, the diode detector and the Y waveguide respectively, and the Y waveguide is connected to the polarization-maintaining fiber ring.

[0008] Furthermore, a lower cover and an upper cover are respectively provided on the two opposite end surfaces of the magnetic shielding sleeve; a mounting groove is provided on the lower cover, and a semicircular arc surface is formed on the side surface corresponding to the surface of the magnetic shielding sleeve.

[0009] Furthermore, the magnetic shielding sleeve is arranged in the installation groove of the base by epoxy resin glue, and the polarization-maintaining optical fiber ring is also coaxially bonded to the inner side of the magnetic shielding sleeve by epoxy resin glue.

[0010] Furthermore, the light source adopts a 1310nm polarization-maintaining SLD light source, and a thermal conductive silicone grease layer is uniformly coated on the mounting surface of the Y waveguide and the bracket.

[0011] Furthermore, the coupler is a 2×2 coupler, and silicone rubber is provided on the connection surface with the bracket.

[0012] Furthermore, the pigtails of the light source and the detector are respectively fused with the pigtail of the input end of the coupler, the pigtail of the output end of the coupler is fused with the pigtail of the input end of the Y waveguide, and the pigtail of the output end of the Y waveguide is fused with the pigtail of the polarization-maintaining fiber ring; melting point protection sleeves are respectively provided at all the fusion joints, and ultraviolet glue is provided for curing.

[0013] Furthermore, all the pigtails are neatly coiled on the end surface of the polarization-maintaining optical fiber ring, and ultraviolet glue is provided for curing.

[0014] Furthermore, the detector is a PIN-FET detector.

[0015] Furthermore, the upper cap is a cylinder with a diameter of 28 mm and an actual installed height of 35.5 mm.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention arranges the light source, coupler, Y waveguide, magnetic shielding sleeve, polarization-maintaining fiber ring and detector on the outer shell, integrates the main board and the optical path system into one without increasing the volume, and has high space utilization. The axes of the heating element (light source) and the temperature sensitive element (polarization-maintaining fiber ring) are perpendicular to each other, so that the measurement direction of the fiber optic gyroscope can be adjusted without changing the original equipment. At the same time, the polarization-maintaining fiber ring is arranged in the magnetic shielding sleeve, and the heating elements such as the light source are placed in the upper cap, that is, they are arranged in different chambers, which greatly reduces the influence of the Shupe effect on the performance of the fiber optic gyroscope. Therefore, the overall structure is compact and the volume is small, and the stability and accuracy of the fiber optic gyroscope are improved.

[0018] (2) The magnetic shielding sleeve of the present invention is provided with a lower cover and an upper cover respectively. The lower cover is provided with a mounting groove and forms a semicircular arc surface, which is convenient for installation and connection, improves the compactness of the overall structure, and reduces the volume.

[0019] (3) In the present invention, the mounting surfaces of the light source and the Y waveguide are respectively coated with a thermal conductive silicone grease layer to facilitate heat dissipation and ensure the reliability of the fiber optic gyroscope. The light source adopts a 1310nm polarization-maintaining SLD light source, which has high reliability and excellent anti-macrobending properties for the small curvature radius of the optical fiber inside the small gyroscope. At the same time, for the harsh application environment of the fiber optic gyroscope, the wide operating temperature range, the high temperature change rate, and the large vibration impact, the light source used has good anti-interference ability and the output light is relatively stable.

[0020] (4) The present invention sets a melting point protection sleeve to protect the fusion joint, and winds the pigtail on the end face of the polarization-maintaining fiber ring, and then sets ultraviolet glue for curing, so as to ensure the reliability of the overall structure installation, thereby ensuring the reliability of the fiber optic gyroscope.

[0021] (5) The upper cap of the present invention is a cylinder with a diameter of 28 mm and an actual installation height of 35.5 mm, which makes the overall structure of the fiber optic gyroscope small in size and high in space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the scheme of the present invention, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0023] Figure 1 It is an overall schematic diagram of the T-shaped small fiber optic gyroscope in the present invention.

[0024] Figure 2 It is a schematic diagram of the interior of the T-shaped small fiber optic gyroscope in the present invention.

[0025] Figure 3 The left side view of the T-shaped small optical fiber gyroscope of the present invention with the upper cap removed.

[0026] Figure 4 It is a cross-sectional view of the T-shaped small fiber optic gyroscope of the present invention.

[0027] The reference numerals are explained as follows: 1-light source, 2-coupler, 3-Y waveguide, 4-detector, 5-detector circuit board, 6-housing, 7-magnetic shielding sleeve, 8-polarization-maintaining fiber ring, 9-lower cover, 10-upper cover, 11-bracket, 12-upper cap. DETAILED DESCRIPTION

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field of the present invention; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the directions or positions indicated by the terms "length", "width", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the drawings, which are only for the convenience of description and should not be understood as limitations on the present technical solution.

[0029] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. In the specification and claims of the present invention and the above-mentioned drawings, when an element is referred to as being "fixed to" or "mounted on" or "disposed on" or "connected to" another element, it may be directly or indirectly located on the other element. For example, when an element is referred to as being "connected to" another element, it may be directly or indirectly connected to the other element.

[0030] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] See also Figures 1 to 4 As shown, the present invention provides a small fiber optic gyroscope with a T-shaped structure, comprising a light source 1, a coupler 2, a Y waveguide 3, a housing 6, a magnetic shielding sleeve 7, a polarization-maintaining fiber ring 8 and a bracket 11.

[0032] The magnetic shielding sleeve 7 and the upper cap 12 are arranged on the housing 6 relative to each other, the surface of the magnetic shielding sleeve 7 is connected to the housing 6, the end surface of one end of the upper cap 12 is connected to the housing 6, and the axial directions of the magnetic shielding sleeve 7 and the upper cap 12 are vertically distributed. The magnetic shielding sleeve 7 is provided with a polarization-maintaining optical fiber ring 8, the upper cap 12 is provided with a bracket 11, and the bracket 11 is provided with a light source 1, Y waveguide 3 andCoupler 2 and Y waveguide 3. The Y waveguide 3 is located between the light source 1 and the coupler 2, and the three are respectively distributed along the axial direction of the upper cap 12. The detector 4 is arranged on the detector circuit board 5, and both are mounted on the bracket 11 and located in the housing 6. The coupler 2 is respectively connected to the light source 1, the detector 4 and the Y waveguide 3, and the Y waveguide 3 is connected to the polarization-maintaining fiber ring 8.

[0033] Specifically, the bracket 11 is provided with a light source base surface, a coupler mounting surface, a mounting groove and a mounting boss, which are used to mount the light source 1, the coupler 2, the Y waveguide 3 and the detector circuit board 5, respectively, so as to facilitate the installation and ensure the compact structure.

[0034] In this embodiment, the light emitted by the light source 1 is divided into two beams of light through the coupler 2, and one of the beams of light enters the Y waveguide 3 to form two beams of light with opposite transmission directions, clockwise and counterclockwise, and enter the polarization-maintaining fiber ring 8. Due to the Sagnac effect of the polarization-maintaining fiber ring 8, the current angular velocity phase shift of the fiber optic gyroscope can be obtained, and then transmitted to the detector 4 through the Y waveguide 3 and the coupler 2, and the detector 4 then transmits it to the external computer through the wire for processing, and the actual angular velocity value can be obtained.

[0035] Furthermore, the two opposite end surfaces of the magnetic shielding sleeve 7 are respectively provided with a lower cover 9 and an upper cover 10 to protect the polarization-maintaining optical fiber ring 8. The lower cover 9 is provided with a mounting groove, and the side surface of the lower cover 9 forms a semicircular arc surface corresponding to the surface of the magnetic shielding sleeve 7, making the overall structure compact without affecting the installation.

[0036] Furthermore, the magnetic shielding sleeve 7 is arranged in the installation groove of the lower cover 9 by epoxy resin glue, and the polarization-maintaining optical fiber ring 8 is also coaxially bonded to the inner side of the magnetic shielding sleeve 7 by epoxy resin glue, which is convenient for installation and can ensure reliable connection. The magnetic shielding sleeve 7 adopts a permalloy magnetic shielding sleeve made of high magnetic permeability material, which can effectively reduce the influence of the Farady effect on the performance of the fiber optic gyroscope.

[0037] Furthermore, the light source 1 adopts a 1310nm polarization-maintaining SLD light source, and a thin layer of thermal conductive silicone grease is evenly coated on the mounting surface of the Y waveguide 3 and the bracket 11 to ensure reliable installation and facilitate heat dissipation.

[0038] The light source 1 in the present embodiment adopts a 1310nm polarization-maintaining SLD light source. Since optical communication mainly has three bands of 850nm, 1310nm and 1550nm, the longer the wavelength is, the shorter the coherence length is, that is, the wider the spectrum is. Different emission modes are adopted for light sources of different wavelengths. 850nm and 1310nm are semiconductor superluminescent diodes, and 1550nm is erbium-doped fiber amplified spontaneous radiation. The present invention adopts a 1310nm light source to meet the requirements of low-precision small gyroscopes. In addition, SLD is a semiconductor light source with a one-way optical gain, and the radiated light is a short coherence length light, which can reduce the coherence error caused by Rayleigh backscattering, polarization cross coupling and Kerr effect, etc. Compared with LED light sources, SLD light sources have large output power, and SLD light sources have good average wavelength stability to ensure the stability of the scale factor of the optical fiber gyroscope, and adopt polarization-maintaining light sources to improve the reliability of the gyroscope.

[0039] Furthermore, the coupler 2 is a 2×2 coupler, and silicone rubber is provided on the connection surface with the bracket 11. The coupler 2 is bonded to the bracket 11 through the silicone rubber, which ensures reliable installation and facilitates signal transmission.

[0040] Furthermore, the detector 4 adopts a PIN-FET detector, which can reliably convert the optical signal into an electrical signal, and then output the voltage after amplifying it through an amplifier, with a simple structure and reliable operation.

[0041] Furthermore, the pigtails of the light source 1 and the detector 4 are fused with the pigtail of the input end of the coupler 2, the pigtail of the output end of the coupler 2 is fused with the pigtail of the input end of the Y waveguide 3, and the pigtail of the output end of the Y waveguide 3 is fused with the pigtail of the polarization-maintaining fiber ring 8. All the fusion joints are respectively provided with melting point protection sleeves for protection, and UV glue is provided for curing.

[0042] Specifically, the bracket 11 is provided with a fiber passage hole for allowing the pigtail fiber of the light source 1 and the pigtail fiber of the detector 4 to pass through, and the center of the end surface at the other end of the upper cap 12 is also provided with a wire outlet hole.

[0043] Furthermore, all the pigtails are neatly coiled on the end surface of the polarization-maintaining optical fiber ring 8, and ultraviolet glue is provided for curing to ensure the compactness of the overall structure.

[0044] Furthermore, the fiber optic gyroscope has a small size and high space utilization. The upper cap 12 is a cylinder with a diameter of only 28 mm and an actual installation height of only 35.5 mm, which is very convenient for many miniaturized devices to reserve space for its installation.

[0045] In this embodiment, the fiber optic gyroscope is installed on other devices through the housing 6, and the upper cap 12 is located inside the device. Therefore, the overall structure and size of the upper cap 12 are very convenient for many miniaturized devices to reserve space for its installation, thereby improving applicability.

[0046] The specific installation process of the T-shaped small fiber optic gyroscope provided by the present invention is as follows:

[0047] 1) A thin layer of thermal conductive silicone grease is evenly applied on the bottom surface of the light source 1, and the light source mounting surface of the bracket 11 is fixed by screws; the coupler 2 is bonded to the coupler mounting surface of the bracket 11 by silicone rubber; a thin layer of thermal conductive silicone grease is evenly applied on the bottom surface of the Y waveguide 3, and the Y waveguide 3 is fixed by screws; wherein the light source 1, the coupler 2 and the Y waveguide 3 are arranged in parallel, and the Y waveguide 3 is located between the light source 1 and the coupler 2.

[0048] 2) Fix the detector 4 on the detector circuit board 5 , and then fix both on the mounting boss of the bracket 11 .

[0049] 3) Pass the pigtail of light source 1 through the light source fiber hole of bracket 11; pass the pigtail of coupler 2 input end and Y waveguide 3 output end through the center of bracket 11, and pass the pigtail of detector 4 through the detector fiber hole of bracket 11; pass the pigtail of coupler 2 output end and Y waveguide 3 input end half a circle through the light source fiber hole of bracket 11.

[0050] 4) Fix the bracket 11 on the housing 6, and pass the pigtail of the light source 1, the pigtail of the coupler 2, the pigtail of the Y waveguide 3 and the pigtail of the detector 4 out from the upper end of the housing 6.

[0051] 5) Use epoxy resin glue to bond the polarization-maintaining fiber ring 8 to the inner side of the magnetic shielding sleeve 7, and then bond the magnetic shielding sleeve 7 to the installation groove of the lower cover 9 with epoxy resin glue, and place the lower cover 9 and the magnetic shielding sleeve 7 as a whole in a temperature box and bake at 80°C for 120 minutes. After cooling to room temperature, fix the lower cover 9 on the housing 6.

[0052] 6) Perform fiber fusion splicing, that is, fuse the pigtail of the light source 1 with the pigtail of one of the input ends of the coupler 2, fuse the pigtail of one of the output ends of the coupler 2 with the pigtail of the input end of the Y waveguide 3, fuse the two output end pigtails of the Y waveguide 3 with the two pigtails of the polarization-maintaining fiber ring 8, and fuse the pigtail of the other input end of the coupler 2 with the pigtail of the detector 4.

[0053] 7) Use a melting point protection sleeve and UV glue to protect the above five pigtail fusion points, coil the pigtail neatly on the upper surface of the polarization-maintaining fiber ring 8, and use UV glue to cure all the pigtails.

[0054] 8) Install the upper cover 10 and the upper cap 12 on the housing 6. The light source 1, the coupler 2 and the Y-waveguide 3 are located in the upper cap 12 and are distributed axially along the upper cap 12. Straighten the wires of the light source 1, the Y-waveguide 3 and the detector 4, pass them through the central wiring hole of the upper cap 12, and coat the wiring hole of the upper cap 12 with silicone rubber for sealing.

[0055] The T-shaped small fiber optic gyroscope provided by the present invention arranges the magnetic shielding sleeve 7 and the upper cap 12 vertically and in a T-shaped structure, and arranges the light source 1, the coupler 2 and the Y waveguide 3 in the axial direction of the upper cap 12 respectively. The measurement direction of the fiber optic gyroscope can be adjusted without changing the original equipment to meet different measurement requirements, thereby ensuring the measurement accuracy of the fiber optic gyroscope and greatly reducing the influence of the Shupe effect on the performance of the fiber optic gyroscope.

[0056] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A T-shaped small fiber optic gyroscope, characterized in that: It includes a light source, a coupler, a Y waveguide, a housing, a magnetic shielding sleeve, a polarization-maintaining optical fiber ring and a bracket; The magnetic shielding sleeve and the upper cap are relatively arranged on the outer shell, and the axial directions of the two are vertically distributed. The surface of the magnetic shielding sleeve is connected to the outer shell, and the end face of one end of the upper cap is connected to the outer shell; a polarization-maintaining fiber ring is arranged in the magnetic shielding sleeve, and a bracket is arranged in the upper cap, and a light source, a Y waveguide and a coupler are arranged on the bracket in sequence; the Y waveguide is located between the light source and the coupler, and the three are distributed along the axial direction of the upper cap respectively; a detector is arranged on the detector circuit board, and the two are installed on the bracket and located in the outer shell; the coupler is connected to the light source, the detector and the Y waveguide respectively, and the Y waveguide is connected to the polarization-maintaining fiber ring.

2. The T-shaped small fiber optic gyroscope according to claim 1, characterized in that: The two opposite end surfaces of the magnetic shielding sleeve are respectively provided with a lower cover and an upper cover; the lower cover is provided with a mounting groove, and the side surface forms a semicircular arc surface corresponding to the surface of the magnetic shielding sleeve.

3. The T-shaped small fiber optic gyroscope according to claim 1 or 2, characterized in that: The magnetic shielding sleeve is arranged in the installation groove of the base by epoxy resin glue, and the polarization-maintaining optical fiber ring is also coaxially bonded to the inner side of the magnetic shielding sleeve by epoxy resin glue; the magnetic shielding sleeve adopts a permalloy magnetic shielding sleeve made of high magnetic permeability material.

4. The T-shaped small fiber optic gyroscope according to claim 3, characterized in that: The light source adopts a 1310nm polarization-maintaining SLD light source, and a thermal conductive silicone grease layer is uniformly coated on the mounting surface of the Y waveguide and the bracket.

5. The T-shaped small fiber optic gyroscope according to claim 1 or 4, characterized in that: The coupler adopts a 2×2 coupler, and silicone rubber is arranged on the connection surface with the bracket.

6. The T-shaped small fiber optic gyroscope according to claim 5, characterized in that: The pigtails of the light source and the detector are respectively fused with the pigtails at the input end of the coupler, the pigtails at the output end of the coupler are fused with the pigtails at the input end of the Y-waveguide, and the pigtails at the output end of the Y-waveguide are fused with the pigtails of the polarization-maintaining optical fiber ring; melting point protection sleeves are respectively provided at all the fusion joints, and ultraviolet glue is provided for curing.

7. The T-shaped small fiber optic gyroscope according to claim 6, characterized in that: All the pigtails are neatly coiled on the end surface of the polarization-maintaining optical fiber ring, and ultraviolet glue is also provided for curing.

8. The T-shaped small fiber optic gyroscope according to claim 1 or 7, characterized in that: The detector is a PIN-FET detector.

9. The T-shaped small fiber optic gyroscope according to claim 1, characterized in that: The upper cap is a cylinder with a diameter of 28 mm and an actual installed height of 35.5 mm.

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