Installation structure and manufacturing method for effectively reducing thermal nonreciprocal error of fiber loop

Abstract

The application relates to an installation structure and a manufacturing method for effectively reducing the thermal nonreciprocity error of an optical fiber coil, and the structural features are as follows: the optical fiber coil installation framework is a composite material framework which is composed of an outer ring part and an inner ring part which are integrally formed; the outer ring part is provided with a ring groove with a U-shaped cross section; in the direction from the inside of the groove to the outside of the groove, the outer ring part is a multilayer composite structure in which the heat conducting material layers and the heat insulation material layers are arranged in an interval mode, and the outermost layer and the innermost layer are both heat conducting material layers; the inner ring part is a multilayer composite structure in which the heat conducting material layers and the heat insulation material layers are arranged in an interval mode, and the outermost layer is a heat conducting material layer; the top of the composite material framework is sealed and fixed with a framework cover plate, so that a closed cavity is formed at the ring groove; the optical fiber coil is only in contact with the bottom of the ring groove in a bottom surface mode; the closed cavity is in a vacuum state or is filled and solidified with a low-thermal-conductivity material; an optical device mounting plate is fixedly connected with the inner ring part, and the material of the optical device mounting plate is consistent with the material of the outermost layer of the inner ring part. The application achieves the purpose of reducing the error and ensuring the output precision of the fiber optic gyroscope.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic gyroscope technology, specifically relating to an installation structure and manufacturing method for effectively reducing thermally induced non-reciprocity errors in fiber optic loops. Background Technology

[0002] As a core component of inertial navigation equipment, the accuracy and performance of fiber optic gyroscopes directly affect the output accuracy of the device. The fiber optic loop, being a sensitive core component of the gyroscope, is highly susceptible to interference from the ambient temperature field, which can reduce the overall accuracy of the gyroscope. Therefore, creating a favorable ambient temperature environment for the fiber optic loop through reasonable structural design, and minimizing the harmful impacts of temperature variations, is a crucial issue that must be addressed in the structural design.

[0003] The core sensitive component of a fiber optic gyroscope—the fiber optic loop—experiences a non-reciprocal phase difference, or Shupe error, when subjected to temperature shocks. This error is a key factor affecting the accuracy output of the fiber optic gyroscope. Therefore, improving the overall accuracy of the fiber optic gyroscope hinges on enhancing the uniformity and stability of the temperature field surrounding the fiber optic loop. Separating the pump laser, drive, and demodulation circuits—heat-generating components—from the fiber optic loop, thus blocking the thermal path between the heat source and the loop's sensitive component, and creating a passive loop sensitive component, is currently the most mainstream structural design solution. However, with the increasing demand for miniaturization and lightweight fiber optic gyroscopes, the integration of the fiber optic loop sensitive component with other heat sources is inevitable. Therefore, designing the fiber optic loop sensitive component as a passive component is unsuitable in the context of miniaturization trends. Furthermore, the fiber optic loop sensitive component installed inside the system may also be affected by convective or radiative heat sources; therefore, a structural design that merely cuts off the heat conduction path cannot fully meet the requirements. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by proposing an installation structure and manufacturing method that effectively reduces the thermally induced non-reciprocity error of the fiber optic loop, thereby ensuring the stability of the fiber optic gyroscope output and thus guaranteeing the output accuracy of inertial navigation equipment.

[0005] One of the above-mentioned objectives of the present invention is achieved by the following technical solution:

[0006] An installation structure for effectively reducing thermally induced non-reciprocity errors in fiber optic loops includes a fiber optic loop mounting frame, a frame cover plate, an optical device mounting plate, and a fiber optic loop. The fiber optic loop mounting frame is a composite material frame structure, generally disc-shaped, consisting of an integrally formed outer ring and an inner ring. A U-shaped groove is provided on the outer ring. From the inside to the outside of the groove, the outer ring is a multi-layered composite structure with alternating layers of thermally conductive material and thermally insulating material or low thermal conductivity material, with both the outermost and innermost layers being thermally conductive material layers. The inner ring is also a multi-layered composite structure with alternating layers of thermally conductive material and thermally insulating material or low thermal conductivity material, with the outermost layer being a thermally conductive material layer.

[0007] The depth of the annular groove is greater than the height of the optical fiber loop, and the width of the annular groove is greater than the width of the optical fiber loop. A frame cover plate is provided on the top of the composite material frame above the annular groove. The frame cover plate is fixedly connected to the top surface of the composite material frame by bonding or welding, so that a closed cavity is formed at the annular groove. The optical fiber loop is fixed in the annular groove only by contacting the bottom surface with the bottom of the annular groove. The closed cavity is in a vacuum state or is filled and solidified with a low thermal conductivity material or a heat-insulating material in the gap between the optical fiber loop and the wall of the closed cavity.

[0008] The inner ring is provided with screw holes, and is fixedly connected to the optical device mounting plate by screws. The material of the optical device mounting plate is the same as the material of the outermost layer of the inner ring of the fiber optic ring mounting frame.

[0009] Furthermore, an adhesive interface agent is provided between adjacent thermally conductive material layers and thermally insulating material layers or low thermal conductivity material layers of the optical fiber ring mounting frame.

[0010] Furthermore, the thermally conductive material layer is made of aluminum alloy, copper, silver, or other metals or non-metals with good thermal conductivity; the thermally insulating material layer or low thermal conductivity material layer is made of soft magnetic alloy, organic material, or composite fabric.

[0011] Moreover, when the thermal insulation material layer or the low thermal conductivity material layer is made of composite material fabric, the fiber reinforcement direction of the composite material fabric is spatially orthogonal.

[0012] Furthermore, fiber outlet holes are pre-reserved on the composite material skeleton; a sleeve is provided on the outside of the pigtail of the optical fiber loop, the sleeve passes through the fiber outlet hole, and a sealing agent is filled in the gap between the sleeve and the outlet hole, so that the pigtail of the optical fiber loop is led out in a sealed manner.

[0013] Furthermore, process holes for vacuuming or injecting insulating fluid are opened on the inner or outer side of the annular groove of the composite material skeleton; after vacuuming or after the insulating fluid has been injected and cured, the process holes are sealed with sealing material.

[0014] The second objective of this invention is achieved through the following technical solution:

[0015] A method for manufacturing an installation structure that effectively reduces the thermally induced non-reciprocity error of fiber optic loops, comprising the following steps:

[0016] Step 1: Determine the working environment, usage conditions, weight, and dimensions of the fiber optic gyroscope. Use a combination of CAD and CAE methods to determine the design scheme for the fiber optic loop frame, including thickness, material selection, and laying method.

[0017] Step 2: Lay and fabricate composite materials for the fiber optic loop frame, cut it to the appropriate size, cure the composite material frame blank, and inspect the material for defects.

[0018] Step 3: The qualified composite material skeleton blank is stamped in one go, the perimeter is trimmed to ensure no burrs, and fiber holes and process holes for vacuuming or injection are machined.

[0019] Step 4: Place the cured fiber loop into the ring groove of the composite material skeleton and bond it to the bottom of the ring groove; then wrap the pigtail with a protective sleeve and pass it through the fiber outlet hole. Install the skeleton end cap at the position corresponding to the ring groove on the top of the composite material skeleton, fix the end cap by welding or bonding, and fix the pigtail on the skeleton end cap.

[0020] Step 5: Perform vacuuming or injection treatment, specifically as follows:

[0021] Vacuuming process:

[0022] First, the fiber outlet hole is sealed with a sealing agent. Then, the air cavity formed between the fiber loop and the frame is evacuated by vacuuming. After the vacuuming is completed, the process hole is immediately sealed to create a vacuum environment for the fiber loop.

[0023] Injection treatment:

[0024] A low thermal conductivity flowable material or a thermally insulating flowable material that does not react with the fiber ring is injected into the air cavity formed between the fiber ring and the frame through the injection process hole; after injection is completed, the process hole and the fiber outlet hole are sealed at the same time.

[0025] Step 6: Install the composite material skeleton containing the fiber loop onto the optical device mounting plate, and connect the pigtail to the Y waveguide on the optical device mounting plate to form an independent fiber loop assembly.

[0026] The advantages and positive effects of this invention are as follows:

[0027] This invention provides an installation structure that effectively reduces thermally induced non-reciprocity errors in fiber optic loops. It achieves thermal path blocking at the fiber optic loop level by using a designable composite material to form a fiber optic loop mounting frame. This frame provides multi-layered heat equalization and insulation for the fiber optic loop. Simultaneously, the multi-layered placement of this frame significantly increases contact thermal resistance, maximally cutting off heat conduction channels. By evacuating the air around the fiber optic loop to create a complete vacuum within the closed cavity formed by the mounting frame and the loop, or by filling the area around the fiber optic loop with a thermally insulating fluid, all paths causing temperature field fluctuations are cut off at the source of the sensitive components. This reduces temperature shock to the fiber optic loop, thereby reducing thermally induced non-reciprocity errors and ensuring the output accuracy of the fiber optic gyroscope. Attached Figure Description

[0028] Figure 1 This is a structural diagram of the sensing component of a traditional fiber optic gyroscope;

[0029] Figure 2 This is a cross-sectional view of the sensing component of a traditional fiber optic gyroscope;

[0030] Figure 3 This is a cross-sectional view of the installation structure of the present invention for effectively reducing the thermally induced non-reciprocal phase difference of the optical fiber loop;

[0031] Figure 4 These are composite material formation pattern diagrams for the bottom of the annular groove of the present invention (not limited to the three forms shown in the diagram), 4a Pattern 1; 4b Pattern 2; 4c Pattern 3. Detailed Implementation

[0032] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0033] This invention provides an installation structure that effectively reduces thermally induced non-reciprocity errors in fiber optic loops. Please refer to [link / reference]. Figures 1-4 The invention lies in designing the traditional metal or purely non-metallic fiber optic loop mounting frame as a composite material, such as... Figure 3 As shown, the composite material is laid in multiple layers, alternating between a thermally conductive material layer (a material with high thermal conductivity) 201 and a thermally insulating material layer or a low thermal conductivity material layer 202. An adhesive interface agent 203 can be added between the thermally conductive material layer 201 and the thermally insulating material layer or the low thermal conductivity material layer 202 to enhance the structural strength of the composite material. The adhesive is a poor thermal conductor.

[0034] In this invention, the composite material skeleton structure is as follows: Figure 3As shown, the composite material skeleton is disc-shaped, consisting of an integrally molded outer ring and an inner ring. A U-shaped groove is provided on the outer ring for mounting the fiber optic loop. The depth of the groove is greater than the height of the fiber optic loop, and the width of the groove is greater than the width of the fiber optic loop. The fiber optic loop is placed within the groove, ensuring that only its bottom surface contacts the bottom 105 of the groove. Gaps 106 are left between the inner and outer sides of the fiber optic loop and the inner and outer walls of the groove, respectively. A gap is also left between the upper layer of the fiber optic loop and the top surface of the groove to maximize the thermally induced non-reciprocal characteristics of the fiber optic loop. Screw holes are provided on the inner ring for fixing the composite material skeleton to the optical device mounting plate 102 of the fiber optic loop. A skeleton cover plate is provided on the top of the composite material skeleton above the groove. The skeleton cover plate is fixedly connected to the top surface of the composite material skeleton by adhesive or welding, thus isolating the fiber optic loop within the groove of the composite material skeleton.

[0035] The outer ring portion, from the inside to the outside of the groove, employs a multi-layered composite structure with alternating layers of thermally conductive material and thermally insulating material or low thermal conductivity material. The outermost and innermost layers are made of thermally conductive material. This ensures that the impact of external heat sources on the frame is uniformly distributed as quickly as possible, preventing uneven heating of the fiber optic ring caused by localized heat accumulation. Similarly, even if a small amount of heat is conducted to the fiber optic ring through the frame, the innermost thermally conductive material layer must ensure that this small amount of heat is evenly distributed, preventing localized heating of the ring.

[0036] The inner ring adopts a multi-layer composite structure consisting of a thermally conductive material layer and a thermally insulating material layer or a low thermal conductivity material layer, with the outermost layer of the inner ring being a thermally conductive material.

[0037] The mounting plate for the optical device is made of the same material as the outermost layer of the composite material skeleton, achieving uniform heat distribution on the outer layer and insulation in the middle.

[0038] In this invention, the designability of the composite material skeleton is reflected in the designability of the number of layers, the materials used, and the thickness of the layers, such as... Figure 4 As shown. The skeleton can be designed specifically for the thermal environment of the actual fiber optic loop and the environmental conditions of the fiber optic gyroscope. For example, if the fiber optic gyroscope skeleton is to have an additional magnetic field shielding function, it is necessary to consider replacing the poorly conductive material 202 with a material or composite fabric with magnetic shielding function. If the mechanical conditions of the environment in which the fiber optic gyroscope is used are harsh, then a composite skeleton made of a material with good specific stiffness should be preferred to provide sufficient stiffness for the fiber optic sensitive components. In addition, as long as the thermally conductive material and the thermally insulating material layers are laid alternately, there can be more than one type of thermally conductive material and more than one type of thermally insulating material layer in the entire composite material skeleton, for example... Figure 4As shown, 201 and 204 are both thermally conductive materials, but they may not be the same type. 202 and 205 are both thermally insulating materials, but they may not be the same type.

[0039] When there is a need for weight reduction in the overall structure, composite fabrics can be used as the main structural element of the skeleton in a layered design. However, the fiber reinforcement directions (directions with good thermal conductivity) of the composite fabric must be spatially orthogonal, for example, 0° / 90° / 0°.

[0040] / 90° or 90° / 0° / 90° / 0°, etc., are used to ensure that the heat conduction path from the composite skeleton to the ring is still an alternating arrangement of heat-conducting material layers and heat-insulating material layers.

[0041] In this invention, the cavity 107 formed by the composite material skeleton 103, the skeleton cover 101, and the optical fiber loop 104 is vacuum-treated or filled with an insulating flowable material or a low thermal conductivity flowable material. After filling, it can be cured and does not react with the optical fiber loop. This provides a relatively uniform and insulating thermal environment for the optical fiber loop.

[0042] In this invention, a process hole (which can be a circular hole) is opened on the inner side 107 or the outer side 108 of the annular groove of the composite material skeleton to be used for vacuuming or injecting thermal insulation flow material or low thermal conductivity flow material. After the thermal insulation material layer has cured, the process hole is blocked to complete the final optical fiber ring skeleton structure.

[0043] In this invention, the composite material skeleton needs to have pre-reserved fiber optic holes for connecting necessary optical components. If the fiber optic loop is insulated by vacuuming, the fiber outlet must be protected with a sleeve and sealed with a sealing agent before vacuuming. If the fiber optic loop is insulated by potting, the potting process hole and the fiber outlet hole should be sealed simultaneously after potting to ensure that the internal and external pressures are the same during potting and that internal air can be smoothly discharged.

[0044] The manufacturing method of this mounting structure, which effectively reduces the thermally induced non-reciprocity error of the optical fiber loop, is as follows:

[0045] Step 1: Determine the working environment, usage conditions, weight, and dimensions of the fiber optic gyroscope. Using a combination of CAD and CAE methods, determine the design scheme for the fiber optic loop frame, including thickness, material selection, and laying method.

[0046] The second step involves laying and fabricating the composite material for the fiber optic ring frame, cutting it to the appropriate size, curing the composite material frame blank, and inspecting the material for defects. Only after the quality inspection is completed can the next step be carried out.

[0047] Step 3: The composite material skeleton blank is stamped and formed in one go, the perimeter is trimmed to ensure no burrs, and circular fiber outlet holes and vacuum or injection process holes are machined.

[0048] Step 4: Place the cured fiber loop into the ring groove of the composite material skeleton and bond it to the bottom of the ring groove. Then, wrap the pigtail with a protective sleeve and pass it through the fiber outlet hole. Install the skeleton end cap at the top of the composite material skeleton corresponding to the position of the ring groove. Fix the end cap by welding or bonding and fix the pigtail on the skeleton end cap.

[0049] Step 5: Perform vacuuming or injection treatment, specifically as follows:

[0050] Vacuuming process:

[0051] First, the fiber outlet hole is sealed with a sealing agent. Then, the air cavity formed between the fiber ring and the frame ring groove is evacuated by vacuuming. After the vacuuming is completed, the process hole is immediately sealed to create a vacuum environment for the ring.

[0052] Injection treatment:

[0053] Insulating or low thermal conductivity fluid material that does not react with the ring is injected into the air cavity formed between the fiber ring and the frame through the injection process hole. This prevents residual water vapor and air in the cavity from forming a new thermal channel between the ring and the frame. After injection is completed, the process hole and fiber outlet hole are sealed at the same time.

[0054] Step 6: Install the composite material skeleton containing the fiber optic loop onto the optical device mounting plate. The optical device mounting plate should be made of the same material as the outer layer of the composite material skeleton. Connect the pigtail to the Y-waveguide on the optical device mounting plate to form an independent fiber optic loop assembly. This assembly will be unaffected by external heat sources. Even if the external heat source is very close to the skeleton, it can still ensure stable output performance of the loop in the face of temperature shocks.

[0055] This fiber optic loop installation structure design effectively blocks the temperature impact of external heat sources on the fiber optic loop. It fundamentally cuts off all heat transfer paths to the fiber optic loop. The alternating placement of thermally conductive and thermally insulating or low-thermal-conductivity materials maximizes the reduction of heat conduction paths between the frame structure and the fiber optic loop. Vacuuming or filling the cavity between the fiber optic loop and the frame with low-thermal-conductivity organic materials further minimizes the impact of heat convection and radiation on the fiber optic loop's temperature. This minimizes the influence of temperature changes on the fiber optic loop, ultimately achieving stable output accuracy for the fiber optic gyroscope.

[0056] The composite material skeleton blank designed in this invention can be manufactured using existing composite material manufacturing processes. Furthermore, the composite material blank can be functionally designed before stamping, allowing for targeted design based on the different operating environments of the fiber optic gyroscope. The thermally conductive material can be aluminum alloy, copper, silver, or other metals or non-metals with good thermal conductivity. The thermally insulating material layer (or a low thermal conductivity material) can be a soft magnetic alloy, organic material, composite fabric, etc. Additionally, the composite material skeleton blank can be formed using lamination molding or, depending on the material, using processes such as spraying. The skeleton stamped using this method completely isolates the sensitive components of the fiber optic gyroscope, ensuring the output accuracy of the fiber optic gyroscope. Therefore, this solution is an important means to improve the accuracy of fiber optic inertial navigation equipment.

[0057] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A mounting structure for effectively reducing thermal nonreciprocal error of a fiber coil, comprising a fiber coil mounting skeleton, a skeleton cover plate, an optical device mounting plate, and a fiber coil, characterized in that: The fiber coil mounting skeleton is a composite skeleton structure, which is in a whole disc type and is composed of an outer ring part and an inner ring part formed integrally; a ring groove with a U-shaped cross section is arranged on the outer ring part; from the inner ring groove to the outer ring groove, the outer ring part is a multi-layer composite structure with the heat conducting material layer and the heat insulation material layer or the low heat conductivity material layer arranged alternately, and the outermost layer and the innermost layer are both the heat conducting material layer; The inner ring part is a multi-layer composite structure with the heat conducting material layer and the heat insulation material layer or the low heat conductivity material layer arranged alternately, and the outermost layer is the heat conducting material layer; The depth of the ring groove is greater than the height of the fiber coil, and the width of the ring groove is greater than the width of the fiber coil; a skeleton cover plate is arranged above the ring groove on the top of the fiber coil mounting skeleton, and the skeleton cover plate is fixedly connected with the top surface of the fiber coil mounting skeleton by bonding or welding, so that a closed cavity is formed at the ring groove; the fiber coil is fixed in the ring groove only by the bottom surface in contact with the bottom of the ring groove; the closed cavity is in a vacuum state or a low heat conductivity material or a heat insulation material is filled and solidified in the gap between the fiber coil and the wall of the closed cavity; A screw passing hole is arranged on the inner ring part, and the passing screw is fixedly connected with an optical device mounting plate, and the material of the optical device mounting plate is consistent with the material of the outermost layer of the inner ring part of the fiber coil mounting skeleton.

2. The mounting structure for reducing the thermal nonreciprocal error of the fiber coil according to claim 1, wherein: An adhesive interface agent is arranged between the adjacent heat conducting material layer and the heat insulation material layer or the low heat conductivity material layer of the fiber coil mounting skeleton.

3. The mounting structure for reducing the thermal nonreciprocal error of the fiber coil according to claim 1, wherein: The heat conducting material layer is made of aluminum alloy, red copper, silver or other metal or non-metal materials with good heat conducting performance; the heat insulation material layer or the low heat conductivity material layer is made of soft magnetic alloy material, organic material or composite fabric.

4. The installation structure for reducing the thermal nonreciprocal error of the fiber coil according to claim 3, characterized by: When the heat insulation material layer or the low heat conductivity material layer is made of the composite fabric, the fiber reinforced direction of the composite fabric is orthogonal in space.

5. The mounting structure for reducing the thermal nonreciprocal error of the fiber coil according to claim 1, wherein: An out-fiber hole is reserved on the fiber coil mounting skeleton; a sleeve is arranged outside the tail fiber of the fiber coil, the sleeve passes through the out-fiber hole, and a sealing agent is filled in the gap between the sleeve and the out-fiber hole, so that the tail fiber of the fiber coil is led out in a sealed manner.

6. The mounting structure for reducing the thermal nonreciprocal error of an optical fiber coil according to claim 1, wherein: A process hole for vacuumizing or filling heat insulation flowing material is opened on the inner side or the outer side of the ring groove of the fiber coil mounting skeleton; after vacuumizing or filling the heat insulation flowing material and solidifying, the process hole is sealed by a sealing material.

7. A manufacturing method of the mounting structure for effectively reducing the thermal non-reciprocity error of the fiber coil according to any one of claims 1-6, comprising the following steps: Step 1: determining the design scheme of the fiber coil mounting skeleton, including the thickness, material selection and laying method, by combining CAD and CAE means according to the working environment, use condition, weight and size of the fiber optic gyroscope; Step 2: performing composite material laying and manufacturing on the fiber coil mounting skeleton, cutting to a suitable size, solidifying the fiber coil mounting skeleton blank, and performing quality inspection on whether the material has defects; Step 3: performing one-time stamping forming on the fiber coil mounting skeleton blank qualified in the quality inspection, trimming the periphery to ensure no burrs, and processing the fiber hole and the process hole for vacuumizing or filling. Step 4: Place the cured fiber coil into the ring groove of the fiber coil mounting skeleton, and bond the bottom surface of the ring groove; then pass the tail fiber through the fiber outlet hole after being wrapped with a protective sleeve, and install a skeleton end cover at the top of the fiber coil mounting skeleton corresponding to the position of the ring groove, and fix the end cover by welding or bonding, and fix the tail fiber on the skeleton end cover; Step 5: Perform vacuum pumping or perfusion treatment, specifically: Vacuum pumping treatment: First, seal the fiber outlet hole with a sealing agent, and then perform vacuum pumping treatment on the air cavity formed between the fiber coil and the ring groove of the fiber coil mounting skeleton, immediately seal the process hole after completing the vacuum pumping treatment, and create a vacuum environment for the fiber coil; Perfusion treatment: Through the perfusion process hole, a low thermal conductivity flowing material or a heat-insulating flowing material that does not react with the fiber coil is perfused into the air cavity formed between the fiber coil and the ring groove of the fiber coil mounting skeleton; after perfusion is completed, the process hole and the fiber outlet hole are sealed at the same time; Step 6: Install the fiber coil mounting skeleton with the fiber coil on the optical device mounting plate, connect the tail fiber with the Y waveguide on the optical device mounting plate, and form an independent fiber coil assembly.

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