Method for rapidly testing local thermal stress suppression effect of optical fiber interferometer

Abstract

The invention discloses a method for rapidly testing a local thermal stress suppression effect of an optical fiber interferometer. The method comprises the following steps: 1) processing an annular epoxy resin sheet; 2) selecting a shielding shell and a sensing coil; 3) placing an epoxy resin sheet, a sensing coil and an epoxy resin sheet in a coil groove of the shielding shell; and finally, the shielding shell cover covers the shielding shell. 4) installing the Y waveguide on the interferometer; (5) a heating source is installed at any position of the surface of the shielding shell, and the heating source is turned on; 6) performing performance test according to a temperature program of the thermal stress suppression effect evaluation test; according to the method, the local thermal stress inhibition effect of the optical fiber interferometer can be rapidly detected, the device testing and screening efficiency can be improved, the production efficiency of the optical fiber gyroscope can be improved, and the production cost of the optical fiber gyroscope can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fiber optic gyroscopes, and in particular to a method for quickly testing the local thermal stress suppression effect of a fiber optic interferometer. Background Art

[0002] Fiber optic gyroscope is an inertial instrument for measuring angular velocity. It has the characteristics of high autonomy and can be used in inertial navigation systems. Due to its all-solid-state structure, wide dynamic range, short start-up time and strong impact resistance, it has been widely used in modern aviation, aerospace and defense industries.

[0003] Five optoelectronic devices are required in a fiber optic gyroscope: light source, fiber coupler, multifunctional phase modulator (Y waveguide), photodetector and fiber ring. Among them, the fiber ring and the optical fiber in the Y waveguide are the main transmission and interference of optical signals, and are devices sensitive to angular velocity. The two constitute the fiber interferometer of the fiber optic gyroscope. The Y waveguide in the fiber interferometer has an independent and complete structure, while the fiber ring is composed of multiple parts. Usually, the fiber ring is made by bonding the sensor coil wound by the panda-type polarization-maintaining fiber and the shielding shell processed by the soft magnetic alloy material. Since the panda-type polarization-maintaining fiber contains two stress zones, it is extremely sensitive to temperature. Therefore, the sensor coil wound by the panda-type polarization-maintaining fiber is also easily affected by temperature. In order to reduce the influence of temperature on the sensor coil, the quadrupole symmetrical winding method, the octupole symmetrical winding method, the hexadecanopole symmetrical winding method and other technologies are usually used in the winding process to suppress the influence of thermal errors caused by temperature. However, since the winding process cannot achieve ideal symmetry, the sensor coil does not suppress the thermal errors thoroughly, and there are often residual thermal errors. These residual thermal errors will enter the fiber ring along with the sensor coil, and then reach the fiber optic gyroscope, eventually causing thermal errors in the fiber ring and fiber optic gyroscope. When there is local heat around the fiber ring or fiber optic gyroscope, local thermal stress will be generated on the fiber interferometer, resulting in a decrease in the temperature performance of the fiber optic gyroscope.

[0004] In the production process of fiber optic gyroscopes, it is often necessary to test and screen the suppression effect of each component on local thermal stress step by step. Taking the Y waveguide and fiber ring that make up the fiber interferometer as an example, for the Y waveguide, it is necessary to test the local thermal stress suppression effect at the Y waveguide component level and the fiber interferometer level; for the sensor coil, it is necessary to test the local thermal stress suppression effect at the sensor coil level, the fiber ring level, and the fiber interferometer level. When the sensor coil is tested at the fiber ring level, epoxy resin glue is needed to bond the sensor coil to the shielding shell. The bonding process includes epoxy resin glue mixing, centrifugal degassing, bonding combination, epoxy resin glue curing, and aging treatment (stress release). These processes have long cycles and occupy a lot of resources, which seriously affects the production efficiency of fiber optic gyroscopes. At the same time, once the fiber ring test does not meet the requirements, the bonded sensor coil and the shielding shell cannot be separated, which will cause waste of the shielding shell, thereby increasing the production cost of the fiber optic gyroscope. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to solve the problems of long cycle, low efficiency and waste of shielding shell in the test and evaluation process of thermal stress suppression effect of the existing optical interferometer, and to provide a rapid test method for the local thermal stress suppression effect of the optical fiber interferometer, which can simplify the evaluation process of the thermal stress suppression effect of the optical fiber interferometer, and can quickly detect the local thermal stress suppression effect of the optical fiber interferometer, thereby improving the efficiency of the temperature performance evaluation of the optical fiber interferometer, improving the efficiency of device testing and screening, and further improving the production efficiency of the optical fiber gyroscope and reducing the production cost of the optical fiber gyroscope.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a method for quickly testing the local thermal stress suppression effect of a fiber interferometer, characterized in that it comprises the following steps: 1) Prepare liquid epoxy resin according to the composition and ratio of epoxy resin used for bonding the sensor coil and the shielding shell in the optical fiber interferometer to be tested, and then cure the liquid epoxy resin in the same way as the epoxy resin in the sensor coil and the shielding shell; and then process the cured epoxy resin into an annular epoxy resin sheet with the same inner and outer diameters as those of the sensor coil; 2) Selecting a shielding shell and a sensing coil that are the same as those of the optical fiber interferometer to be tested, wherein the shielding shell includes a shielding shell and a shielding shell cover, and the shielding shell has a coil slot; 3) Place a piece of epoxy resin sheet in the coil slot of the shielding shell, then put the sensor coil into the coil slot, and pass the two pigtails of the sensor coil through the fiber outlet holes of the shielding shell; then place a piece of epoxy resin sheet on the other side of the sensor coil; finally, cover the shielding shell cover on the shielding shell, and fix the shielding shell cover to the shielding shell with high-temperature resistant tape, and make the shielding shell cover, epoxy resin sheet, sensor coil, epoxy resin sheet and the bottom of the coil slot fit in sequence; then perform step 4) or step 5); 4) Install the Y waveguide on the interferometer and fuse the two optical fibers of the Y waveguide with the two pigtail fibers of the sensor coil; then proceed to step 5); 5) Install a heating source at any position on the surface of the shielding shell and turn on the heating source to generate a local hot zone; 6) Perform performance test according to the temperature procedure of thermal stress suppression effect evaluation test; 7) Repeat steps 5) and 6) to test different locations until the test is completed; 8) Finally, remove the high temperature resistant tape and separate the shielding shell, shielding shell cover, sensor coil and epoxy resin sheet. The epoxy resin sheet can be reused.

[0007] Furthermore, the thickness of the epoxy resin sheet is 2 mm±0.3 mm.

[0008] Furthermore, in step 1), after the epoxy resin sheet is processed and formed, both side surfaces thereof are polished so that the epoxy resin sheet can fit with the sensing coil and the bottom of the coil slot.

[0009] Furthermore, the high temperature resistant tape can withstand at least 150°C.

[0010] Compared with the prior art, the present invention has the following advantages: using an epoxy resin sheet made of the same composition and curing method as the epoxy resin for bonding the sensing coil and the shielding shell to replace the bonding process, while ensuring the same heat transfer efficiency as the bonding state, greatly shortening the test time, simplifying the evaluation process of the thermal stress suppression effect of the optical fiber interferometer, improving the efficiency of the temperature performance evaluation of the optical fiber interferometer, being able to quickly detect the local thermal stress suppression effect of the optical fiber interferometer, and improving the device testing and screening efficiency; at the same time, in this method, there is no need to bond the sensing coil and the shielding shell, avoiding the waste of the shielding shell when the sensing coil is scrapped due to poor temperature performance, and saving engineering costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the assembly structure of each component during the test of the present invention.

[0012] In the figure: 1—epoxy resin sheet, 21—shielding shell, 22—shielding shell cover, 3—sensing coil. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0014] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0016] Example: See Figure 1 A method for quickly testing the local thermal stress suppression effect of a fiber interferometer, characterized in that it comprises the following steps: 1) Prepare liquid epoxy resin according to the composition and ratio of epoxy resin used for bonding the sensor coil 3 and the shielding shell in the optical fiber interferometer to be tested; then cure the liquid epoxy resin in the same way as the epoxy resin (same) in the sensor coil 3 and the shielding shell. Then process the cured epoxy resin into an annular epoxy resin sheet 1 with the same inner and outer diameters as the sensor coil 3. The thickness of the epoxy resin sheet 1 is 2mm±0.3mm. In actual processing, after the epoxy resin sheet 1 is processed and formed, its two sides are polished so that the epoxy resin sheet 1 can fit with the side of the sensor coil 3 and the bottom of the coil slot of the shielding shell.

[0017] 2) Select a shielding shell and a sensing coil 3 that are the same as those of the optical fiber interferometer to be tested, wherein the shielding shell includes a shielding shell 21 and a shielding shell cover 22, and the shielding shell 21 has a coil groove.

[0018] 3) Place a piece of epoxy resin sheet 1 in the coil slot of the shielding shell 21, then place the sensor coil 3 in the coil slot, and pass the two pigtails of the sensor coil 3 through the fiber outlet holes of the shielding shell. Place another piece of epoxy resin sheet 1 on the other side of the sensor coil 3. Finally, cover the shielding shell 21 with the shielding shell cover 22, and fix the shielding shell cover 22 to the shielding shell 21 with high-temperature resistant tape, and make the shielding shell cover 22, epoxy resin sheet 1, sensor coil 3, epoxy resin sheet 1 and the bottom of the coil slot fit in sequence to form a fiber ring. Among them, the high-temperature resistant tape refers to a tape that can withstand at least 150°C (i.e., the maximum curing temperature of epoxy resin). Then perform step 4) or step 5); among them, step 4) is to perform a thermal stress test on the interferometer, and if step 5) is performed directly, the fiber ring is subjected to a thermal stress test.

[0019] 4) Install the Y waveguide on the interferometer and fuse the two optical fibers of the Y waveguide with the 32 pigtail fibers of the sensor coil; then proceed to step 5).

[0020] 5) Install a heating source at any position on the surface of the shielding shell and turn on the heating source to generate a local hot zone.

[0021] 6) Perform performance tests according to the temperature procedure of the thermal stress suppression effect evaluation test.

[0022] 7) Repeat steps 5) and 6) to test different locations until the test is completed.

[0023] 8) Finally, remove the high temperature resistant tape and separate the shielding shell 21, the shielding shell cover 22, the sensor coil 3 and the epoxy resin sheet 1, wherein the epoxy resin sheet 1 can be reused.

[0024] This solution uses an epoxy resin sheet made with the same composition and curing method as the epoxy resin used to bond the sensor coil and the shielding shell to replace the bonding process. Under the premise of ensuring the same heat transfer efficiency as the bonding state, the test time is greatly shortened, the evaluation process of the thermal stress suppression effect of the optical fiber interferometer is simplified, the efficiency of the temperature performance evaluation of the optical fiber interferometer is improved, the local thermal stress suppression effect of the optical fiber interferometer can be quickly detected, and the device testing and screening efficiency can be improved; at the same time, this method does not need to bond the sensor coil and the shielding shell, avoiding the waste of the shielding shell when the sensor coil is scrapped due to poor temperature performance, saving engineering costs.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for quickly testing the local thermal stress suppression effect of a fiber interferometer, characterized in that: The steps include: 1) Prepare liquid epoxy resin according to the composition and ratio of epoxy resin used for bonding the sensor coil and the shielding shell in the optical fiber interferometer to be tested, and then cure the liquid epoxy resin in the same way as the epoxy resin in the sensor coil and the shielding shell; and then process the cured epoxy resin into an annular epoxy resin sheet with the same inner and outer diameters as those of the sensor coil; 2) Selecting a shielding shell and a sensing coil that are the same as those of the optical fiber interferometer to be tested, wherein the shielding shell includes a shielding shell and a shielding shell cover, and the shielding shell has a coil slot; 3) Place a piece of epoxy resin sheet in the coil slot of the shielding shell, then put the sensor coil into the coil slot, and pass the two pigtails of the sensor coil through the fiber outlet holes of the shielding shell; then place a piece of epoxy resin sheet on the other side of the sensor coil; finally, cover the shielding shell cover on the shielding shell, and fix the shielding shell cover to the shielding shell with high-temperature resistant tape, and make the shielding shell cover, epoxy resin sheet, sensor coil, epoxy resin sheet and the bottom of the coil slot fit in sequence; then perform step 4) or step 5); 4) Install the Y waveguide on the interferometer and fuse the two optical fibers of the Y waveguide with the two pigtail fibers of the sensor coil; then proceed to step 5); 5) Install a heating source at any position on the surface of the shielding shell and turn on the heating source to generate a local hot zone; 6) Perform performance test according to the temperature procedure of thermal stress suppression effect evaluation test; 7) Repeat steps 5) and 6) to test different locations until the test is completed; 8) Finally, remove the high temperature resistant tape and separate the shielding shell, shielding shell cover, sensor coil and epoxy resin sheet. The epoxy resin sheet can be reused.

2. A method for quickly testing the local thermal stress suppression effect of a fiber interferometer according to claim 1, characterized in that: The thickness of the epoxy resin sheet is 2 mm±0.3 mm.

3. A method for quickly testing the local thermal stress suppression effect of a fiber interferometer according to claim 1, characterized in that: In step 1), after the epoxy resin sheet is processed and formed, both sides thereof are polished so that the epoxy resin sheet can fit with the sensor coil and the bottom of the coil slot.

4. A method for quickly testing the local thermal stress suppression effect of a fiber interferometer according to claim 1, characterized in that: High temperature resistant tape can withstand at least 150℃.

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