CN104677290B - Twin-core fiber grating micro-scale measurement probe manufacturing method based on self assembly principle - Google Patents

Abstract

The method for making a micro-scale measurement probe of a double-core fiber grating based on the principle of self-assembly belongs to the technical field of precision instrument manufacturing; the method adopts machining or hydrofluoric acid fiber corrosion treatment to reduce the diameter of the single-mode fiber after the fiber grating is written, Then two single-mode optical fibers with reduced diameter and written fiber gratings are passed through a thin tube with an inner taper angle, and the lower ends are immersed in low-viscosity ultraviolet glue, and self-assembled by capillary force, thereby Form the most compact side-by-side structure. After self-assembly, two self-assembled single-mode fibers with reduced diameters and written fiber gratings are cured with UV glue to make a double-core fiber grating. Grinding, processing a spherical needle tip at the grinding end of the dual-core fiber grating by using the molten fiber method or the microsphere installation method, and completing the processing of the dual-core fiber grating probe; the fiber grating signal of the present invention has no crosstalk, low cost, and low loss.

Description

Fabrication method of dual-core fiber grating microscale measurement probe based on self-assembly principle

technical field

The invention belongs to the technical field of precision instrument manufacturing, in particular to a method for manufacturing a double-core optical fiber grating microscale measuring probe based on the self-assembly principle.

Background technique

With the continuous development of the aerospace industry, automobile industry, electronics industry and cutting-edge industries, the demand for precision and tiny components has increased dramatically. Due to the limitations of the space scale and the shadowing effect of the tiny components to be measured, as well as the influence of the measurement contact force, it is becoming more and more difficult to achieve precise measurement of the scale of tiny components, especially the difficulty in improving the depth of the measurement of tiny inner cavity components, which has become a constraint on the development of the industry the "bottleneck". In order to achieve smaller size measurement and increase the measurement depth, the most widely used method is to use a slender probe to penetrate into the inner cavity of tiny components for detection, and measure the tiny inner dimensions at different depths by aiming at the signal. Therefore, at present, the precision measurement method of tiny component size is mainly based on the detection method of coordinate measuring machine combined with aiming trigger probe. Since the development of coordinate measuring machine technology has been relatively mature, it can provide precise three-dimensional space movement, so aiming trigger probe The detection method of the probe becomes the key to the design of the detection system for small component sizes. Moreover, the fiber grating probe can completely overcome the shadowing effect and break through the limitation of the probe on the measurement depth due to its advantages of separating the sensor and the measurement system. Fabrication of microscale measurement probes.

At present, the micro-scale measurement probes designed based on fiber gratings include the following:

In 2011, Professor Cui Jiwen and Yang Fuling of Harbin Institute of Technology in China proposed a micropore size measurement device and method based on FBGBending. This method uses a fiber grating probe, a light source, and a detection device to form an aiming trigger system, and cooperates with dual-frequency laser interference. The length measuring device of the instrument can obtain the micropore diameter of different sections. When the fiber grating probe touches the deformation of this method, the main stress of the probe does not act on the fiber grating, the resolution of the system is very low, the three-dimensional measurement capability is not available, and the performance is difficult to further improve.

In 2014, Professor Cui Jiwen and Feng Kunpeng of Harbin Institute of Technology in China proposed a micro-scale measurement device and method based on multi-core fiber gratings. In this method, a special multi-core fiber grating probe is designed to make the probe touch the workpiece. The stress generated in the process fully acts on the fiber grating, which greatly improves the detection resolution of the previous microhole size measurement device and method based on FBG Bending; moreover, different multi-core optical fiber core distribution structures can realize two-dimensional , The decoupling of 3D measurement has good measurement properties. However, this method writes fiber gratings on a special multi-core fiber. On the one hand, the writing process of the multi-core fiber will cause the problem of crosstalk between the core and the core; on the other hand, the purchased multi-core fiber makes the probe As a result, the probe structure parameters cannot be designed independently.

In summary, among the existing micro-scale measurement probes based on fiber grating design, the multi-core fiber grating probe has been widely concerned due to its high resolution and multi-dimensional measurement decoupling characteristics, and has a good application prospect. The existing multi-core fiber grating probes mainly have the following problems:

1. Considering the production cost of the multi-core fiber grating probe, the multi-core fiber can only be selected from the special model of the fiber manufacturer, and the multi-core fiber with a special structure cannot be designed according to the measurement requirements to make the multi-core fiber grating probe.

2. When making a multi-core fiber grating probe, it is necessary to use the excimer laser phase mask method to write the fiber grating on the multi-core fiber. The core distance of the multi-core fiber is only tens of microns. When the fiber grating is written on the core, it will affect the adjacent fiber cores, resulting in writing crosstalk, and finally the multi-core fiber grating probe, the fiber grating in each core has low reflectivity and severe spectral distortion, which seriously affects the accuracy of the measurement.

3. When the multi-core fiber grating probe is in use, it is necessary to obtain the reflection spectrum of the fiber grating in each core of the multi-core fiber, so each multi-core fiber grating probe needs to be installed with a multi-core fiber fan-out connector to achieve multi-core Each fiber core of the optical fiber is coupled with an external single-mode optical fiber, but this kind of joint is expensive and has a large optical loss, which is not suitable for the promotion and application of multi-core fiber grating probes in micro-scale measurement.

Contents of the invention

The purpose of the present invention is to solve the problems that the multi-core fiber structure is limited by the manufacturer, the writing crosstalk and the light loss of the fan-out connector in the application of the multi-core fiber grating probe, and proposes a micro-scale dual-core fiber grating based on the principle of self-assembly The manufacturing method of the measurement probe is to use the self-assembly method to make the ordinary single-mode optical fiber after the fiber grating is written into a dual-core fiber grating micro-scale measurement probe, and the dual-core fiber grating micro-scale measurement probe can be designed according to the measurement requirements Moreover, this method ensures that each channel of the manufactured dual-core fiber grating micro-scale measuring probe is connected to an ordinary single-mode optical fiber without fan-out connectors, achieving flexible structural design, good spectral signals, and low optical loss , the purpose of low cost.

The technical solution of the present invention is: a method for manufacturing a dual-core fiber grating microscale measurement probe based on the principle of self-assembly, the method comprising the following steps:

(1). Reduce the diameter of the single-mode fiber after writing the fiber grating

Take two single-mode optical fibers with a length of 100-1000mm after writing the fiber grating. The coating layer of the single-mode fiber after the fiber grating is stripped near the end of the fiber grating region with a length of 50-80 mm, and then mechanical treatment is used to reduce the coating layer of the single-mode fiber after the fiber grating is written. Diameter: Straighten the single-mode fiber after writing the fiber grating, fix both ends on the fixture of the synchronous rotating motor and make the rotation axis of the single-mode fiber after writing the fiber grating coincide with the rotation axis of the synchronous rotating motor. A rotating wheel wrapping the abrasive sheet is installed above the rotating shaft of the single-mode fiber behind the fiber Bragg grating. The wheel wrapping the abrasive sheet is close to and contacts the single-mode fiber after the fiber Bragg grating is written and is stripped along the single-mode fiber after the fiber Bragg grating is written. The coating layer moves repeatedly at a constant speed for grinding. At the same time, a microscopic observation system is used to detect the diameter of the stripped coating layer of the single-mode fiber after the fiber grating is written. When the diameter of the part is reduced to 50-100 μm, stop grinding; use a fiber cutter to cut off the 30-50 mm single-mode fiber after the fiber grating grating area on the single-mode fiber after the fiber grating is written, Make the fiber grating grating area at the end of the single-mode optical fiber after the fiber grating has been written with a reduced diameter, and keep the fiber grating grating area at a length of 5-10 mm, and then place it in an ultrasonic cleaning machine equipped with absolute ethanol for 5-5 mm. 20 minutes;

(2).Self-assembly of two single-mode optical fibers with reduced diameter and written fiber gratings

Prepare a thin tube with a length of 10-30mm, an inner taper angle at one end, and an inner diameter of (50-100μm)×3+(1-5)μm, and write the two fiber gratings with reduced diameters after the treatment in step (1) Insert the final single-mode optical fiber from the inner taper angle of one end of the thin tube to ensure that the ends of the two reduced-diameter single-mode optical fibers after writing fiber gratings are flush and extend 5-10mm beyond the end of the thin tube; fix the thin tube vertically and Immerse the two single-mode optical fibers with reduced diameter beyond one end of the thin tube and write fiber gratings in a glass cup filled with UV glue with a viscosity less than 100cp. Under the capillary force, the low viscosity UV glue goes along The two single-mode fibers with reduced diameters and written fiber gratings move upward, and make the two single-mode fibers with reduced diameters written with fiber gratings close together to form the most compact parallel structure. After 5-15 minutes, the thin tube and the two self-assembled single-mode fibers with reduced diameter after writing the fiber grating are taken out from the ultraviolet glue , to ensure that the two self-assembled single-mode fibers with reduced diameters after writing fiber gratings are not misaligned, and use a UV glue curing light source to fix the two self-assembled fiber gratings with reduced diameters beyond one end of the thin tube The single-mode optical fiber is irradiated for 1 to 10 minutes to complete the curing of the ultraviolet glue to form a dual-core fiber grating; then, drop the heat-curing glue at the inner cone angle at one end of the thin tube and fill the inner cone angle, and insert the dual-core fiber grating Place the thin tube on a constant temperature electric heater at 50-180°C and heat it for 10-60 minutes to cure the heat-curing glue in the inner cone angle at one end of the thin tube;

(3). End face grinding of dual-core fiber grating

Fix the thin tube with the dual-core fiber grating inserted in step (2) on the fiber grinder, adjust the height of the thin tube so that the dual-core fiber grating is in contact with the polishing sheet on the fiber grinder, and then grind according to the FC/PC fiber optic connector. Grind the end face of the dual-core fiber grating by using the end face observation device to confirm that it is flat, free of cracks and incompleteness, stop the end face grinding of the dual-core fiber grating and wipe the end face clean with a dust-free paper dipped in alcohol;

(4). Fabricate the spherical tip of the dual-core fiber grating end after the end face is ground

Fused fiber method: fix the fine tube at the upper end of the double-core fiber grating after the end face grinding in step (3) vertically, adjust the height of the thin tube so that the lower end of the double-core fiber grating after the end face grinding is at the two discharge electrodes of the EDM At the position 0.5-3mm below the center of the needle tip, adjust the discharge time and discharge current of the EDM machine, use the heat generated by the EDM to melt the 0.5-3mm optical fiber at the lower end of the double-core fiber grating after the end face is ground, and use the gravity and the melting of the optical fiber The surface tension forms a good fiber optic ball, and after it cools down, a fiber spherical needle tip is formed at the lower end of the double-core fiber grating after end grinding, and the processing of the spherical needle tip at the end of the dual-core fiber grating after end grinding is completed; The processing quality of the optical fiber spherical tip is verified. It is required that the concentricity between the optical fiber spherical tip and the dual-core optical fiber grating after grinding the end face is less than 5 μm, the optical fiber ball has no bubbles and damage, and the ratio of the diameter of the optical fiber ball to the diameter of the dual-core optical fiber grating after grinding the end face. Greater than or equal to 1.2, select qualified dual-core fiber grating probes, and complete the production of dual-core fiber grating probes.

The advantages of the present invention are:

1. Use the single-mode fiber after the fiber grating is written to make the dual-core fiber grating probe. The structural parameters of the dual-core fiber grating probe can be designed according to the measurement requirements, such as the diameter, length and spherical tip diameter of the dual-core fiber grating probe.

2. The dual-core fiber grating probe is made of the single-mode fiber after the fiber grating is written, which avoids the writing crosstalk caused by writing the fiber grating directly on the multi-core fiber. The completed dual-core fiber grating probe has the characteristics of good spectral signal .

3. The dual-core fiber grating probe is made of the single-mode optical fiber after the fiber grating is written. The dual-core fiber grating probe pigtail comes with a single-mode pigtail, which avoids the use of fan-out connectors and reduces the use of dual-core fiber grating probes. The cost and optical loss in.

Description of drawings

Fig. 1 is the device diagram of reducing the diameter of the single-mode fiber after the optical fiber grating is written by the method of mechanical processing;

Figure 2 is a diagram of a single-mode fiber self-assembly device after the fiber grating is written after the diameter is reduced;

Fig. 3 is the sectional view of A-A in Fig. 2;

Fig. 4 is a schematic diagram of the capillary structure in Fig. 2;

Fig. 5 is a diagram of a dual-core fiber grating end face grinding device;

Fig. 6 is a diagram of a device for forming a spherical needle tip by the molten optical fiber method;

Fig. 7 is the method for hydrofluoric acid optical fiber corrosion treatment to reduce the single-mode optical fiber diameter device diagram after writing optical fiber grating;

Figure 8 is a top view of Figure 7;

Fig. 9 is a schematic diagram of forming a spherical needle tip by the microsphere installation method;

Fig. 10 is a partial schematic diagram of the structure of part B in Fig. 9;

In the figure: 1. Single-mode optical fiber after fiber grating writing, 2. Fiber grating grating area, 3. Rotary wheel wrapped with abrasive sheet, 4. Synchronous rotating motor, 5. Fixing device, 6. Writing optical fiber after diameter reduction Single-mode fiber after grating, 7. Thin tube, 8. Inner cone angle, 9. Glass cup, 10. Ultraviolet glue, 11. Dual-core fiber grating, 12. Optical fiber grinder, 13. Grinding sheet, 14. End face grinding 15. Electrode, 16. EDM, 17. Optical fiber spherical needle tip, 18. Plastic bucket cover, 19. Plastic bucket, 20. Hydrofluoric acid solution, 21. Ruby spherical needle tip, 22. Level Platform, 23. V-shaped groove, 24. Six degrees of freedom adjustment device.

detailed description

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

A method for manufacturing a dual-core fiber grating microscale measurement probe based on the principle of self-assembly, the method comprising the following steps:

(1). Reduce the diameter of the single-mode fiber after writing the fiber grating

Take two single-mode optical fibers 1 with a length of 100-1000 mm after writing the fiber grating. The fiber grating area 2 is at the position of 30-50 mm at one end of the single-mode optical fiber 1 after the fiber grating is written. The length of the fiber grating area 2 is 10-50 mm. 20mm, peel off the coating layer of the 50-80mm portion of the end of the single-mode fiber 1 after the fiber grating is written near the fiber grating region 2, and then use mechanical treatment to reduce the size of the single-mode fiber 1 after the fiber grating is written. Strip the diameter of the coating layer: straighten the single-mode fiber 1 after writing the fiber grating, fix the two ends on the fixing device 5 of the synchronous rotating motor 4 and make the rotation axis of the single-mode fiber 1 after writing the fiber grating and The rotation axes of the synchronous rotating motor 4 are coincident, and a runner 3 wrapping the abrasive sheet is installed above the rotation axis of the single-mode optical fiber 1 after the fiber grating is written. The optical fiber 1 is repeatedly moved at a constant speed along the stripped coating layer of the single-mode optical fiber 1 after the fiber grating is written, and is ground. Diameter, when the diameter of the single-mode optical fiber 1 after the optical fiber grating is stripped is reduced to 50-100 μm, stop grinding; the single-mode optical fiber with the optical fiber grating after the optical fiber grating is reduced in diameter Cut off the 30-50mm single-mode optical fiber after the fiber grating grating area 2 on 6, so that the fiber grating grating area 2 is at the end of the single-mode optical fiber 1 after the fiber grating is written with a reduced diameter, and keep the fiber grating grating area 2 The length is 5-10mm, and then placed in an ultrasonic cleaner filled with absolute ethanol for 5-20 minutes;

(2).Self-assembly of two single-mode optical fibers with reduced diameter and written fiber gratings

Prepare a thin tube 7 with a length of 10-30 mm, an inner cone angle of 8 at one end, and an inner diameter of (50-100 μm)×3+(1-5) μm, and write the two diameter-reduced tubes after step (1) The single-mode optical fiber 6 behind the fiber grating is inserted from the inner cone angle 8 at one end of the thin tube 7 to ensure that the ends of the two reduced-diameter single-mode optical fibers 6 after writing the optical fiber grating are flush and exceed the end of the thin tube 7 by 5-10mm ; Vertically fix the capillary 7 and immerse the two reduced-diameter single-mode optical fibers 6 beyond one end of the capillary 7 after writing the fiber grating into the glass 9 filled with ultraviolet glue 10 with a viscosity less than 100cp for 3-6mm , under the capillary force, the low-viscosity ultraviolet glue 10 moves upward along the two single-mode optical fibers 6 after the fiber grating is written with the reduced diameter, and makes the two single-mode optical fibers 6 after the fiber grating is written with the reduced diameter Closely close to form the most compact juxtaposed structure, self-assemble two single-mode optical fibers 6 with reduced diameters after writing fiber gratings; The reduced single-mode optical fiber 6 after writing the fiber grating is taken out from the ultraviolet glue to ensure that the self-assembled two single-mode optical fibers 6 with reduced diameter after writing the fiber grating are not misaligned, and the light source is cured with ultraviolet glue 10 Irradiate the two single-mode optical fibers 6 with reduced diameter and written fiber gratings beyond one end of the thin tube 7 after self-assembly for 1 to 10 minutes to complete the curing of the ultraviolet glue to form a dual-core fiber grating 11; then, at one end of the thin tube 7 Drop heat-curing glue into the inner cone angle 8 of the inner cone angle 8 and fill the inner cone angle 8. Put the narrow tube 7 inserted with the dual-core fiber grating 11 on a constant temperature electric heater at 50-180°C for 10-60 minutes to make the thin tube The thermosetting glue in the inner cone angle 8 at one end of the pipe 7 is cured;

(3). End face grinding of dual-core fiber grating

Fix the capillary 7 with the dual-core fiber grating 11 inserted in the step (2) on the optical fiber grinder 12, adjust the height of the capillary 7 so that the dual-core fiber grating 11 contacts the polishing sheet 13 on the fiber grinder 12, Then grind the end face according to the grinding method of the FC/PC optical fiber connector, and use the end face observation device to confirm that it is flat, without cracks and incompleteness, stop the end face grinding of the dual-core fiber grating 11 and wipe the end face clean with a dust-free paper dipped in alcohol;

(4). Processing of spherical needle tip at the end of dual-core fiber grating after end grinding

Fused optical fiber method: the thin tube 7 at the upper end of the dual-core optical fiber grating 14 after the end face grinding in step (3) is vertically fixed, and the height of the thin tube 7 is adjusted so that the lower end of the double-core optical fiber grating 14 after the end face grinding is placed in the electric discharge machine 16. Two discharge electrodes 15 are located 0.5-3 mm below the center of the needle tip. Adjust the discharge time and discharge current of the EDM machine 16, and use the heat generated by the EDM to grind the end face of the double-core fiber grating 14 to 0.5-3 mm from the lower end of the optical fiber. Melting, using gravity and the surface tension of the molten optical fiber to form a good optical fiber ball, after cooling, a spherical fiber tip 17 is formed at the lower end of the dual-core fiber grating 14 after end grinding, and the end of the dual-core optical fiber grating 14 after end grinding The processing of the spherical tip; the processing quality of the optical fiber spherical tip 17 is verified under an electron microscope, and the coaxiality between the optical fiber spherical tip 17 and the double-core fiber grating 14 after end grinding is required to be less than 5 μm, and the optical fiber ball has no bubbles and damage. The ratio of the diameter of the spherical needle tip 17 to the diameter of the dual-core fiber grating 14 after end grinding is greater than or equal to 1.2, and a qualified dual-core fiber grating probe is selected to complete the processing of the dual-core fiber grating probe.

In step (1), reducing the diameter of the single-mode optical fiber 1 after writing the fiber grating can also be treated by hydrofluoric acid corrosion, and passing the single-mode optical fiber 1 after writing the fiber grating downward through the plastic bucket cover 18. The microholes are fixed, and a hydrofluoric acid solution 20 with a volume fraction of 10-50% is added to the plastic bucket 19, and the end of the single-mode optical fiber 1 stripped of the coating layer after the optical fiber grating is written is immersed in a volume fraction of 10-50%. 50% hydrofluoric acid solution 20 60 ~ 90mm, take out the single-mode fiber 1 after writing the fiber grating from the plastic bucket 7 every 2030 minutes, measure the single-mode fiber 1 after writing the fiber grating under the electron microscope and strip The diameter of the coating layer part; when the diameter of the single-mode optical fiber 1 after the optical fiber grating is written and the coating layer is stripped is reduced to 50-100 μm by corrosion, the single-mode optical fiber 6 after the optical fiber grating is written after the diameter is reduced Take out from the plastic barrel 19 and put into the glass barrel that acetone is housed, make the end of the single-mode optical fiber 6 stripping the coating layer part after the reduction of the diameter after writing the optical fiber grating, immerse in the acetone 80～90mm, do 10～ Softening treatment for 30 minutes; use a fiber cutter to cut off the 30-50mm single-mode optical fiber after the fiber grating grating area 2 on the fiber grating grating area 2 after the reduced diameter of the single-mode optical fiber after the fiber grating is written, so that the fiber grating after the reduced diameter is written The fiber grating grating area 2 on the single-mode optical fiber 6 is at the end of the single-mode optical fiber 6 after the fiber grating is written after the diameter is reduced, and it is ensured that the fiber grating grating area 2 on the single-mode optical fiber 6 after the optical fiber grating is written The length is 5-10 mm, and then placed in an ultrasonic cleaner filled with absolute ethanol for washing for 5-20 minutes.

In step (2), the material of the thin tube 7 is quartz or metal.

In step (4), a spherical needle tip can also be processed at the end of the dual-core fiber grating 14 after end grinding by using the microsphere installation method: the fine tube at the upper end of the dual-core fiber grating 14 after end grinding in step (3) 7. Fix it horizontally on the six-degree-of-freedom adjustment device 24, and apply ultraviolet glue 10 on the polished end with a dispensing needle, and manually adjust the six-degree-of-freedom adjustment device 24 under the visual monitoring system to make the double-core fiber grating 14 after the end surface is ground One end coated with UV glue 10 is close to the ruby spherical needle point 21 fixed in the V-shaped groove 23 on the horizontal platform 22, and the double-core fiber grating 14 after the end face grinding is aligned with the center of the ruby spherical needle point 21, and the double-core fiber grating after the end face grinding is pushed forward. The optical fiber grating 14 is in contact with the ruby spherical needle tip 21, and then irradiates the contact point with an ultraviolet glue curing light source for 1 to 10 minutes to complete the processing of the spherical needle tip at the end of the dual-core optical fiber grating 14 after end grinding, and to complete the double-core optical fiber grating probe. processing.

The ratio of the diameter of the ruby spherical needle point 21 to the diameter of the double-core optical fiber grating 14 after end face grinding is greater than or equal to 1.2.

The technical innovations and beneficial technical effects of the method of making dual-core fiber grating micro-scale measurement probes based on the principle of self-assembly are: the dual-core fiber grating probe is made by using the single-mode fiber after the fiber grating is written, which avoids directly inserting the fiber grating on the multi-core fiber. Writing fiber gratings on it brings writing crosstalk, and the completed dual-core fiber grating probe has the characteristics of good spectral signals, which can improve the signal-to-noise ratio of the output signal of the dual-core fiber grating probe; the invention can design dual-core fiber optics according to measurement requirements The structural parameters of the grating probe, such as the diameter of the double-core fiber grating probe, the length and the diameter of the spherical needle point, etc., have the characteristics of flexible design and manufacture; the double-core fiber grating probe made by the present invention comes with a single-mode pigtail, Avoiding the use of multi-core optical fiber fan-out connectors greatly reduces the cost and optical loss in the use of dual-core fiber grating probes, which is conducive to the promotion and application of dual-core fiber grating probes in the field of micro-scale measurement.

Claims (5)

1. A method for making a dual-core fiber grating micro-scale measurement probe based on the principle of self-assembly, characterized in that: the method may further comprise the steps: (1). Reduce the diameter of the single-mode fiber after writing the fiber grating Take two single-mode optical fibers with a length of 100-1000mm after writing the fiber grating. The coating layer of the single-mode fiber after the fiber grating is stripped near the end of the fiber grating region with a length of 50-80 mm, and then mechanical treatment is used to reduce the coating layer of the single-mode fiber after the fiber grating is written. Diameter: Straighten the single-mode fiber after writing the fiber grating, fix both ends on the fixture of the synchronous rotating motor and make the rotation axis of the single-mode fiber after writing the fiber grating coincide with the rotation axis of the synchronous rotating motor. A rotating wheel wrapping the abrasive sheet is installed above the rotating shaft of the single-mode fiber behind the fiber Bragg grating. The wheel wrapping the abrasive sheet is close to and contacts the single-mode fiber after the fiber Bragg grating is written and is stripped along the single-mode fiber after the fiber Bragg grating is written. The coating layer moves repeatedly at a constant speed for grinding. At the same time, a microscopic observation system is used to detect the diameter of the stripped coating layer of the single-mode fiber after the fiber grating is written. When the diameter of the part is reduced to 50-100 μm, stop grinding; use a fiber cutter to cut off the 30-50 mm single-mode fiber after the fiber grating grating area on the single-mode fiber after the fiber grating is written, Make the fiber grating grating area at the end of the single-mode optical fiber after the fiber grating has been written with a reduced diameter, and ensure that the fiber grating grating area is 5-10mm in length, and then place it in an ultrasonic cleaning machine equipped with absolute ethanol for 5-5 mm. 20 minutes; (2).Self-assembly of two single-mode optical fibers with reduced diameter and written fiber gratings Prepare a thin tube with a length of 10-30mm, an inner taper angle at one end, and an inner diameter of (50-100μm)×3+(1-5)μm, and write the two fiber gratings with reduced diameters after the treatment in step (1) Insert the final single-mode optical fiber from the inner taper angle of one end of the thin tube to ensure that the ends of the two reduced-diameter single-mode optical fibers after writing fiber gratings are flush and extend 5-10mm beyond the end of the thin tube; fix the thin tube vertically and Immerse the two single-mode optical fibers with reduced diameter beyond one end of the thin tube and write fiber gratings in a glass cup filled with UV glue with a viscosity less than 100cp. Under the capillary force, the low viscosity UV glue goes along The two single-mode fibers with reduced diameters and written fiber gratings move upward, and make the two single-mode fibers with reduced diameters written with fiber gratings close together to form the most compact parallel structure. After 5-15 minutes, the thin tube and the two self-assembled single-mode fibers with reduced diameter after writing the fiber grating are taken out from the ultraviolet glue , to ensure that the two self-assembled single-mode fibers with reduced diameters after writing fiber gratings are not misaligned, and use a UV glue curing light source to fix the two self-assembled fiber gratings with reduced diameters beyond one end of the thin tube The single-mode optical fiber is irradiated for 1 to 10 minutes to complete the curing of the ultraviolet glue to form a dual-core fiber grating; then, drop the heat-curing glue at the inner cone angle at one end of the thin tube and fill the inner cone angle, and insert the dual-core fiber grating Place the thin tube on a constant temperature electric heater at 50-180°C and heat it for 10-60 minutes to cure the heat-curing glue in the inner cone angle at one end of the thin tube; (3). End face grinding of dual-core fiber grating Fix the thin tube with the dual-core fiber grating inserted in step (2) on the fiber grinder, adjust the height of the thin tube so that the dual-core fiber grating is in contact with the polishing sheet on the fiber grinder, and then grind according to the FC/PC fiber optic connector. Grind the end face of the dual-core fiber grating by using the end face observation device to confirm that it is flat, free of cracks and incompleteness, stop the end face grinding of the dual-core fiber grating and wipe the end face clean with a dust-free paper dipped in alcohol; (4). Fabrication of spherical needle tip at the end of dual-core fiber grating after end grinding Fused fiber method: fix the thin tube at the upper end of the double-core fiber grating after the end face grinding in step (3) vertically, adjust the height of the thin tube so that the lower end of the double-core fiber grating after the end face grinding is at the two discharge electrodes of the EDM At the position 0.5-3mm below the center of the needle tip, adjust the discharge time and discharge current of the EDM machine, use the heat generated by the EDM to melt the 0.5-3mm optical fiber at the lower end of the double-core fiber grating after the end face is ground, and use gravity and the melting of the optical fiber The surface tension forms a good fiber optic ball, and after it cools down, a fiber spherical needle tip is formed at the lower end of the double-core fiber grating after end grinding, and the processing of the spherical needle tip at the end of the double-core fiber grating after end grinding is completed; The processing quality of the optical fiber spherical tip is verified. It is required that the concentricity between the optical fiber spherical tip and the dual-core fiber grating after end grinding is less than 5 μm, the optical fiber ball has no bubbles and damage, and the ratio of the diameter of the optical fiber ball to the diameter of the dual-core optical fiber grating after end grinding Greater than or equal to 1.2, select qualified dual-core fiber grating probes, and complete the production of dual-core fiber grating probes. 2. according to claim 1, based on the self-assembly principle of the dual-core fiber grating micro-scale measurement probe manufacturing method, it is characterized in that: the step (1) reduces the single-mode fiber diameter after writing the fiber grating and can also use hydrogen Treatment method of hydrofluoric acid corrosion: pass the single-mode optical fiber after writing the fiber grating down through the microhole on the plastic bucket cover and fix it, add a hydrofluoric acid solution with a volume fraction of 10-50% into the plastic bucket and make the writing The end of the single-mode optical fiber after the optical fiber grating is stripped of the coating layer is immersed in a hydrofluoric acid solution with a volume fraction of 10-50% for 60-90mm, and the single-mode optical fiber after the optical fiber grating is written is removed from the plastic every 20-30 minutes. Take it out from the bucket, and measure the diameter of the stripped coating layer part of the single-mode fiber after the fiber grating is written under an electron microscope; when the fiber grating is written, the diameter of the stripped coating layer part of the single-mode fiber is reduced to 50~ When the diameter is 100 μm, take out the single-mode optical fiber with reduced diameter from the plastic barrel and put it into a glass barrel filled with acetone, so that the single-mode optical fiber with reduced diameter after the optical fiber grating is stripped. The end of the cladding part is immersed in acetone for 80-90 mm, and softened for 10-30 minutes; use a fiber cutter to cut the single-mode optical fiber 30-50 mm behind the fiber grating grating area on the single-mode fiber after the fiber grating has been reduced in diameter. The mode fiber is cut off, so that the fiber grating grating area is at the end of the single-mode fiber after the fiber grating is written with reduced diameter, and the length of the fiber grating grating area is guaranteed to be 5-10mm, and then placed in an ultrasonic chamber filled with absolute ethanol. Wash in the washing machine for 5-20 minutes. 3. The method for manufacturing the microscale measuring probe based on self-assembly principle of dual-core fiber grating according to claim 1, characterized in that: in step (2), the material of the capillary is quartz or metal. 4. according to claim 1 based on the self-assembly principle of the dual-core fiber grating micro-scale measurement probe manufacturing method, it is characterized in that: in step (4), also can adopt the microsphere mounting method to grind the double-core after the end face Process a spherical needle tip at the end of the fiber grating: fix the thin tube at the upper end of the double-core fiber grating after the end surface is ground in step (3) horizontally on the six-degree-of-freedom adjustment device, and apply UV light to the ground end with a dispensing needle. Glue, manually adjust the six-degree-of-freedom adjustment device under the visual monitoring system, so that the end of the double-core fiber grating coated with UV glue after end face grinding is close to the ruby spherical needle tip fixed in the V-shaped groove on the horizontal platform, and the end face of the double-core fiber grating after grinding After aligning with the center of the ruby spherical tip, push the double-core optical fiber grating with the end face ground into contact with the ruby spherical tip, and then irradiate the contact point with a UV glue curing light source for 1 to 10 minutes to complete the processing of the dual-core optical fiber grating spherical tip. A dual-core fiber grating probe is made. 5. According to claim 4, the method for making a micro-scale measuring probe based on the self-assembly principle of a double-core fiber grating is characterized in that: the ratio of the diameter of the ruby spherical tip to the diameter of the double-core fiber grating after end face grinding is greater than or equal to 1.2.