An optical fiber sensor based on high-purity quartz pressure sensitive element and its preparation method

Abstract

The present invention discloses an optical fiber sensor based on a high-purity quartz pressure sensitive element and a preparation method thereof, comprising an optical fiber, a quartz sleeve, and a high-purity quartz pressure sensitive element; a through hole is provided in the quartz sleeve, and the optical fiber is inserted into the through hole; the quartz pressure sensitive element is connected to the quartz sleeve. The present invention can be applied to harsh environments such as corrosion resistance except for hydrofluoric acid and hot phosphoric acid above 150°C. Since biological tissues do not reject quartz materials, it is also applicable to applications such as monitoring of intracranial pressure; and it is fixed without glue by laser hot melting, which can improve stability, reliability and scope of application; the thickness of the quartz pressure sensitive element is controlled by an optical cold processing process, and no chemical corrosion and other processes are required, thereby improving the stability, reliability and life of the optical fiber sensor head; the manufacturing process of the present invention is simple and fast, the sensor is safe and reliable, and has good stability, and combined with the traditional optical cold processing process, it can achieve hot melting of quartz pressure sensitive elements with extremely small thickness.

Description

Technical Field

[0001] The invention relates to the fields of optical fiber technology, Fabry-Perot interference and laser hot-melt cross-talk of high-purity quartz, and in particular to an optical fiber sensor based on a high-purity quartz pressure sensitive element and a preparation method thereof. Background Art

[0002] Fiber optic sensors have the characteristics of electrical insulation, anti-electromagnetic interference, high sensitivity, high temperature and corrosion resistance, passive sensor end and therefore intrinsic safety, long-distance transmission without signal conversion and amplifier, small size and light weight, so they have broad application prospects in the fields of communications, civil engineering, petrochemicals, aerospace, etc. Fabry-Perot fiber interferometer medium and low pressure sensors have great potential in medium and low pressure applications because the pressure sensitive element can sense very small pressure. In recent years, with the in-depth research and application of this type of fiber optic low-pressure sensor, people have paid attention to finding a fiber optic low-pressure sensor that is simple, fast, safe, reliable, stable, and can be used in various harsh environments.

[0003] In the Fabry-Perot fiber interferometer low-pressure sensor, the use of adhesives or the viscosity of certain chemical materials is a common method to construct and fix the pressure sensitive element of the sensor. A silicon chip or a pressure sensitive element of a certain chemical material is fixed on the tapered end face of the capillary. However, there are the following disadvantages: (1) After being fixed with adhesives such as epoxy resin, the thermal expansion coefficient of the adhesive will affect the temperature performance of the optical fiber sensor, and it cannot be used at high temperatures, which cannot meet the requirements of using optical fiber sensors in harsh environments and cannot give full play to the advantages of optical fiber sensors; (2) When the pressure sensitive element is fixed on the end face of the capillary using the viscosity of a certain chemical material, the sensor is affected. When subjected to ultrasonic or other strong vibration signals, the pressure sensitive element is prone to fall off from the end face, causing the optical fiber sensor to completely fail. At the same time, it cannot meet the requirements of harsh high-temperature environments. (3) If it is a quartz pressure sensitive element, the commonly used method is to fix the pressure sensitive element by gluing. However, the adhesive is prone to aging and the thermal expansion coefficient of the adhesive is much larger than that of quartz, which leads to performance deterioration or failure of the sensor such as the working point drift. At the same time, the adhesive cannot withstand use in high-temperature environments and is easily corroded in harsh environments, causing the pressure sensitive element to loosen or fall off. Because biological tissues do not reject quartz materials, it is suitable for applications such as intracranial pressure monitoring. Summary of the invention

[0004] The purpose of the present invention is to provide an optical fiber sensor based on high-purity quartz pressure sensitive elements and a preparation method thereof to solve the problems existing in the above-mentioned prior art. The manufacturing process is simple and quick, the sensor is safe, reliable and has good stability. Combined with the traditional optical cold processing technology, it can realize the hot melting of quartz pressure sensitive elements with extremely small thickness. It is suitable for various harsh environments except hydrofluoric acid and hot phosphoric acid above 150°C. Because biological tissues do not reject quartz materials, it is suitable for applications such as monitoring of intracranial pressure.

[0005] To achieve the above object, the present invention provides the following solution: an optical fiber sensor based on a high-purity quartz pressure sensitive element, comprising an optical fiber, a quartz sleeve, and a high-purity quartz pressure sensitive element;

[0006] The quartz sleeve is provided with a through hole, and the optical fiber is inserted into the through hole; the quartz pressure sensitive element is connected to the quartz sleeve.

[0007] Preferably, a through hole with a trapezoidal pit is provided in the quartz sleeve;

[0008] Preferably, the quartz pressure sensitive element and the quartz sleeve are fixed to each other by laser hot melting without glue.

[0009] Preferably, before the quartz pressure sensitive element and the quartz sleeve are fixed to each other without glue by laser hot melting, the quartz pressure sensitive element needs to be temporarily fixed to the end face of the quartz sleeve by optical glue.

[0010] Preferably, the end face of the optical fiber and the inner surface of the quartz pressure sensitive element form a Fabry-Perot cavity.

[0011] Preferably, the thickness of the quartz pressure sensitive element is controlled by an optical cold working process.

[0012] A method for preparing an optical fiber sensor based on a high-purity quartz pressure sensitive element comprises the following steps:

[0013] S1. Select a quartz sleeve with a length of 6-8 mm, use a femtosecond laser to process the end face of the quartz sleeve, and quickly process a regular and smooth trapezoidal pit. Place the processed quartz sleeve in an alcohol solution for ultrasonic cleaning for 2-5 minutes, repeat the cleaning 2-3 times, and finally dry it at 100°C for 1-2 hours; and use an optical cold processing process to frost and polish the end face of the trapezoidal pit of the quartz sleeve, with a finish of not less than level 12, and at the same time ensure that its end face is perpendicular to the axis of the sleeve, and the verticality error is less than 1 degree. Finally, wipe the polished end face clean with anhydrous alcohol;

[0014] S2, frosting and polishing one surface of the quartz pressure sensitive element to a smoothness of 3-6, frosting and polishing the other surface of the quartz pressure sensitive element to a smoothness of 12 or above, and processing the thickness to a required thickness between 15 microns and 500 microns, and then wiping the frosted and polished pressure sensitive element clean with anhydrous alcohol;

[0015] S3, placing the quartz pressure sensor processed in S2 in a constant temperature box at 300° C. for 24 hours and then cooling naturally for annealing;

[0016] S4, the quartz pressure sensitive element after annealing in S3 is heated by CO 2 Cut it into a square with a side length of about 1.3 times the diameter of the quartz sleeve by laser, and then wipe it clean with anhydrous alcohol;

[0017] S5, using the high finish of the glass surface to adsorb the quartz pressure sensitive material cut in S4 onto the end surface of the quartz sleeve;

[0018] S6, fix the quartz pressure sensitive element adsorbed by the optical glue to the end face of the quartz sleeve and the edge close to the end face of the quartz sleeve by laser heat melting, and fix the excess quartz pressure sensitive element around the quartz sleeve by CO 2 Laser cut, then place it in a 300℃ constant temperature oven for 24-48 hours and then cool it naturally for annealing;

[0019] S7. Design the cavity length of the Fabry-Perot cavity of the stationary sensor and fix the processed optical fiber into the quartz sleeve using ultraviolet optical glue.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] (1) The optical fiber sensor of the present invention is made of all quartz material, which can be used in harsh environments such as corrosion resistance except for hydrofluoric acid and hot phosphoric acid above 150°C. Since biological tissues do not reject quartz materials, it is also suitable for applications such as monitoring intracranial pressure.

[0022] (3) The thickness of the quartz pressure sensitive element is controlled by an optical cold processing process, without the need for chemical corrosion and other processes, thus improving the stability, reliability and life of the optical fiber sensor head;

[0023] (4) The manufacturing process of the present invention is simple and quick, the sensor is safe, reliable and has good stability, and combined with the traditional optical cold processing technology, it can realize the hot melting of quartz pressure sensitive elements with extremely small thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 It is a schematic diagram of the structure of the optical fiber sensor based on the quartz pressure sensitive element of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] Reference Figure 1 As shown, the present invention provides an optical fiber sensor based on a quartz pressure sensitive element, comprising an optical fiber, a quartz sleeve with a trapezoidal pit, and a thin quartz pressure sensitive element. The optical fiber sensor is made of all quartz materials and is suitable for harsh environments such as corrosion resistance except hydrofluoric acid and hot phosphoric acid above 150°C. The quartz pressure sensitive element is fixed to the end face of the sleeve by laser hot melting without glue, thereby improving stability, reliability and application range. Before laser hot melting, the glass pressure sensitive element is temporarily fixed to the end face of the sleeve by optical glue, and the end face of the optical fiber fixed in the quartz sleeve and the inner surface of the glass pressure sensitive element form a Fabry-Perot cavity; the thickness of the quartz pressure sensitive element is controlled by an optical cold processing process, and no chemical corrosion process is required, thereby improving the stability, reliability and life of the optical fiber sensor head; when external static or dynamic pressure changes act on the glass pressure sensitive element, the cavity length of the Fabry-Perot cavity changes, and external pressure change information is demodulated according to the cavity length change information.

[0030] A method for preparing an optical fiber sensor based on a quartz pressure sensitive element comprises the following steps:

[0031] Step 1: Select a quartz sleeve with a length of 6-8 mm, use a femtosecond laser to process the end face of the quartz sleeve, and quickly process a regular and smooth trapezoidal pit to insert the optical fiber and form the Fabry-Perot cavity of the sensor. Place the processed quartz sleeve in an alcohol solution for ultrasonic cleaning for 2-5 minutes, repeat the cleaning 2-3 times, and finally dry it at 100°C for 1-2 hours; and use an optical cold processing process to frost and polish the trapezoidal pit end face of the quartz sleeve, with a finish of not less than level 12, and ensure that its end face is perpendicular to the axis of the sleeve, and the verticality error is less than 1 degree. Finally, wipe the polished end face clean with anhydrous alcohol;

[0032] Step 2: frosting and polishing one surface of the quartz pressure sensitive element to a smoothness of 3-6, frosting and polishing the other surface of the quartz pressure sensitive element to a smoothness of 12 or above, and processing the thickness to a required thickness between 15 microns and 500 microns, and then wiping the frosted and polished pressure sensitive element clean with anhydrous alcohol;

[0033] Step 3: Place the quartz pressure sensor processed in step 2 in a constant temperature box at 300° C. for 24 hours and then cool it naturally for annealing, so as to release the internal residual stress generated in the ultra-thin quartz pressure sensor during the grinding and polishing process, and reduce the probability of cracks and fissures in the ultra-thin pressure sensor during the laser melting process;

[0034] Step 4: Use CO 2 Cut it into a square with a side length of about 1.3 times the diameter of the quartz sleeve by laser, and then wipe it clean with anhydrous alcohol;

[0035] Step 5: Using the high finish of the glass surface, the pressure sensitive optical glue cut in step 4 is adsorbed onto the end face of the quartz sleeve;

[0036] Step 6: fix the quartz pressure sensitive element adsorbed to the end face of the quartz sleeve and the edge close to the end face of the quartz sleeve by laser hot melting, and fix the excess quartz pressure sensitive element around the quartz sleeve by CO 2 Laser cut it off, then place it in a constant temperature box at 300℃ for 24-48 hours and then cool it naturally for annealing to release the internal residual stress caused by hot melting;

[0037] Step 7: Design the cavity length of the Fabry-Perot cavity of the stationary sensor and glue the processed optical fiber into the quartz sleeve.

[0038] The manufacturing process of the invention is simple and fast, the sensor is safe, reliable and has good stability, and combined with the traditional optical cold processing technology, it can realize the hot melting of quartz pressure sensitive elements with extremely small thickness, and is suitable for various harsh environments except hydrofluoric acid and hot phosphoric acid above 150°C.

[0039] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0040] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An optical fiber sensor based on a high-purity quartz pressure sensitive element, characterized in that: Including optical fiber, quartz sleeve, high-purity quartz pressure sensitive element; The quartz sleeve is provided with a through hole, and the optical fiber is inserted into the through hole; the quartz pressure sensitive element is connected to the quartz sleeve; The method for preparing the optical fiber sensor comprises the following steps: S1. Select a quartz sleeve with a length of 6-8 mm, use a femtosecond laser to process the end face of the quartz sleeve, and quickly process a regular and smooth trapezoidal pit. Place the processed quartz sleeve in an alcohol solution for ultrasonic cleaning for 2-5 minutes, repeat the cleaning 2-3 times, and finally dry it at 100°C for 1-2 hours; and use an optical cold processing process to frost and polish the end face of the trapezoidal pit of the quartz sleeve, with a finish of not less than level 12, and at the same time ensure that its end face is perpendicular to the axis of the sleeve, and the verticality error is less than 1 degree. Finally, wipe the polished end face clean with anhydrous alcohol; S2, frosting and polishing one surface of the quartz pressure sensitive element to a smoothness of 3-6, frosting and polishing the other surface of the quartz pressure sensitive element to a smoothness of 12 or above, and processing the thickness to a required thickness between 15 microns and 500 microns, and then wiping the frosted and polished pressure sensitive element clean with anhydrous alcohol; S3, placing the quartz pressure sensor processed in S2 in a constant temperature box at 300° C. for 24 hours and then cooling naturally for annealing; S4, using a CO2 laser to cut the quartz pressure sensitive element after the annealing treatment in S3 into a square with a side length of 1.3 times the diameter of the quartz sleeve, and then wipe it clean with anhydrous alcohol; S5, using the high finish of the glass surface to adsorb the quartz pressure sensitive material cut in S4 onto the end surface of the quartz sleeve; S6, fix the quartz pressure sensitive element adsorbed by the optical glue to the end face of the quartz sleeve and the edge close to the end face of the quartz sleeve by laser hot melting, and at the same time cut off the excess quartz pressure sensitive element around the quartz sleeve by CO2 laser, and then place it in a constant temperature box at 300° C. for 24-48 hours and then cool it naturally for annealing treatment; S7. Design the cavity length of the Fabry-Perot cavity of the stationary sensor and fix the processed optical fiber into the quartz sleeve using ultraviolet optical glue.

2. The optical fiber sensor based on high-purity quartz pressure sensitive element according to claim 1, characterized in that: A through hole with a trapezoidal pit is arranged in the quartz sleeve.

3. The optical fiber sensor based on high-purity quartz pressure sensitive element according to claim 1 is characterized in that: The quartz pressure sensitive element and the quartz sleeve are fixed to each other by laser hot melting without glue.

4. The optical fiber sensor based on high-purity quartz pressure sensitive element according to claim 3 is characterized in that: Before the quartz pressure sensitive element and the quartz sleeve are fixed without glue by laser hot melting, the quartz pressure sensitive element needs to be temporarily fixed on the end face of the quartz sleeve by optical glue.

5. The optical fiber sensor based on high-purity quartz pressure sensitive element according to claim 1, characterized in that: The end face of the optical fiber and the inner surface of the quartz pressure sensitive element form a Fabry-Perot cavity.

6. The optical fiber sensor based on high-purity quartz pressure sensitive element according to claim 1, characterized in that: The thickness of the quartz pressure sensitive element is controlled by an optical cold working process.

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