A miniature fiber optic probe sensor for in-situ monitoring of acoustoluminescence intensity

Abstract

This invention relates to a miniature fiber optic probe sensor for in-situ monitoring of sonoluminescence intensity. It introduces a weak light signal into a photodetector through a light probe, and then uses the photodetector to detect the sonoluminescence intensity. This invention solves the problem of equipment durability in harsh underground environments (high pressure, corrosion), achieves accurate in-situ detection of sonoluminescence signals, and meets the miniaturized deployment requirements of underground scenarios.

Description

Technical Field

[0001] This invention belongs to the field of acoustic emission signal detection technology, specifically relating to a miniature fiber optic probe sensor for in-situ monitoring of acoustic emission intensity. Background Technology

[0002] Sonoluminescence is a phenomenon produced by the cavitation of ultrasound. It is a physical phenomenon in which sound energy is converted into light energy. The process is accompanied by extreme high temperature and pressure and ultraviolet radiation, which can generate hydroxyl radicals in situ.

[0003] In industrial sites, chlorinated hydrocarbons (such as tetrachloroethylene PCE and trichloroethylene TCE) are chemically stable, highly hydrophobic, and easily migrate and diffuse in underground environments, making them difficult-to-degrade organic pollutants that pose a serious threat to the ecological environment and human health.

[0004] The hydroxyl radicals generated by sonoluminescence can undergo an oxidation reaction with chlorinated hydrocarbon pollutants, degrading them into harmless substances. Therefore, sonoluminescence can serve as a novel pathway for the degradation of chlorinated hydrocarbon pollutants.

[0005] This necessitates in-situ monitoring of sonoluminescence intensity to dynamically adjust ultrasonic emission parameters. However, applying existing fiber optic sensors to complex and porous soil media presents significant challenges: existing fiber optic sensors are easily damaged in high-pressure underground environments and cannot accurately detect sonoluminescence intensity. Therefore, a pressure-resistant fiber optic sensor with enhanced light collection efficiency is needed for use under these conditions. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art by providing a miniature fiber optic probe sensor for in-situ monitoring of sonoluminescence intensity, which solves the problem that ordinary fiber optic sensors in the prior art cannot adapt to high-pressure underground environments and cannot accurately detect sonoluminescence intensity.

[0007] This invention proposes a miniature fiber optic probe sensor for in-situ monitoring of acoustic emission intensity, the miniature fiber optic probe sensor comprising: Optical fiber, used for transmitting optical signals; the optical fiber includes at least one core and at least one cladding layer; Ultraviolet-visible light detectors are used to convert optical signals into quantifiable electrical signals; Pressure-resistant enclosure, used for structural pressure-resistant support in high-pressure environments and as an isolation and protective layer against highly corrosive media.

[0008] Furthermore, the pressure-resistant packaging shell includes an outer shell and an inner layer, and both the outer shell and the inner layer are formed by an integral molding process. The outer shell is made of alumina ceramic material, and the inner layer is a composite oxygen-free copper metal layer.

[0009] Furthermore, the end of the optical fiber is designed as a tapered structure, and the sidewalls are polished to reduce light scattering. The tapered probe end of the optical fiber extends 1.2-2mm beyond the front end of the pressure-resistant encapsulation shell.

[0010] Furthermore, the apex angle of the conical structure is 60°, and the roughness Ra of the sidewall after polishing is ≤0.1μm.

[0011] Furthermore, the optical fiber and the pressure-resistant encapsulation shell are provided with a guide hole at the front end and an outlet channel at the rear end, and the interface of the guide hole and the outlet channel are filled with high-pressure resistant silicone sealant with a thickness of 0.1mm.

[0012] Furthermore, the high-pressure resistant silicone sealant adopts a segmented curing process, that is, it is cured at room temperature for 2 hours and then cured at 80°C for 1 hour to ensure that the sealing gap is ≤0.01mm.

[0013] Furthermore, the fiber core is made of quartz material, and the fiber core is a single-mode optical fiber with a diameter of 8μm and a refractive index of 1.46±0.002.

[0014] Furthermore, the edges of the fiber core end are rounded to R0.5mm and the surface is passivated.

[0015] Furthermore, the passivation treatment is performed by using a chromate passivation process to passivate the surface of the fiber core.

[0016] Furthermore, the spectral response range of the ultraviolet-visible detector is 200nm-760nm.

[0017] Compared with existing technologies, this invention solves the problem of equipment durability in harsh underground environments (high pressure, corrosion), achieves accurate in-situ detection of acoustic emission signals, and meets the miniaturized deployment requirements of underground scenarios. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0020] Figure 1 This is a schematic diagram of the structure of the miniature fiber optic probe sensor for in-situ monitoring of sonoluminescence intensity according to the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection. It should be understood that the present invention can be implemented in many different ways and should not be considered as limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure more thorough and complete, and to fully convey the scope of the invention to those skilled in the art.

[0022] Please see Figure 1 The miniature fiber optic probe sensor for in-situ monitoring of acoustic emission intensity in this embodiment includes an optical fiber 1, an ultraviolet-visible light detector 2, and a pressure-resistant encapsulation shell 3.

[0023] The optical fiber 1 includes a core 101 and a cladding 102. The probe end of the optical fiber 1 is fabricated into a tapered structure with a 60° apex angle, and the sidewalls are polished (roughness Ra≤0.1μm) to improve light collection efficiency and transmission stability.

[0024] The tapered detection end of the optical fiber 1 extends 1.2mm beyond the front end of the pressure-resistant encapsulation shell 3 (the exposed length is adapted to the contact requirements of the underground medium), and the length of the optical fiber embedded inside the encapsulation shell is 15mm. The coaxiality of the optical fiber and the central axis of the encapsulation shell is calibrated by a laser positioning instrument to ensure that the deviation is ≤0.02mm, avoiding optical transmission path deviation. Furthermore, in order to enhance the weather resistance of the sensor, the interfaces of the optical fiber 1 with the front guide hole 4 and the rear lead-out channel 5 of the pressure-resistant encapsulation shell 3 are filled with high-pressure resistant silicone sealant (temperature resistance range -20℃-120℃), with the sealant layer thickness controlled at 0.1mm. A segmented curing process is adopted, namely, 2 hours of curing at room temperature + 1 hour of high-temperature curing at 80℃, to ensure that the sealing gap is ≤0.01mm, blocking the penetration of underground high-pressure media and corrosive fluids, while buffering the stress contact between the optical fiber and the encapsulation shell.

[0025] The fiber core 101 uses quartz material (purity ≥99.999%) as the substrate, and the core diameter is made of single-mode optical fiber. The core is prepared by vapor deposition with a diameter of 8μm, and its refractive index is controlled at 1.46±0.002. The end edge of the fiber core 101 is rounded to R0.5mm, and the surface is passivated (using chromate passivation process) to enhance wear resistance and corrosion resistance.

[0026] The cladding 102 is made of low-refractive-index quartz glass with a thickness of 25 μm and a refractive index set at 1.44 ± 0.002, ensuring that the refractive index difference between the fiber core and the cladding is stable at 0.02 ± 0.004, meeting the requirements for total internal reflection transmission of optical signals. The prepared fiber core and cladding are then composited using a melt-drawing process, with the total diameter of the optical fiber controlled at 58 μm and the length cut to 16.2 mm as needed.

[0027] The ultraviolet-visible light detector 2 is a miniature silicon photodiode, which is directly bonded to the base inside the pressure-resistant encapsulation shell 3 via eutectic bonding. The photosensitive surface of the detector is precisely aligned with the output end of the optical fiber core. The detector covers a spectral response range of 200nm-760nm and incorporates a low-noise amplifier circuit.

[0028] The pressure-resistant encapsulation shell 3 is made of a ceramic-metal composite material, including an outer layer of alumina ceramic 301 and an inner layer of oxygen-free copper metal 302, forming a ceramic-metal composite structure. The final overall thickness of the encapsulation shell is 2.5mm, and the pressure resistance rating is ≥30MPa. A 0.6mm diameter fiber guide hole is opened at the front end of the pressure-resistant encapsulation shell, and a fiber lead-out channel is reserved at the rear end. The inner wall of the channel is smoothed to prevent fiber wear. The ceramic-metal composite structure of the pressure-resistant encapsulation shell improves its pressure resistance and corrosion resistance. Furthermore, the encapsulation shell 3 includes two sub-cavities. By cascading multiple sub-cavities, the sealing performance of the encapsulation shell 3 can be further improved. Multiple sub-cavities can form a stepped structure. To facilitate coaxial alignment of the fiber and the detector, multiple stepped structures can be used to easily adjust the fiber height.

[0029] The alumina ceramic outer layer 301 is made by mixing alumina ceramic powder (purity ≥99.5%) with a binder and pressing it into shape through powder metallurgy process. The mold size corresponds to the outer diameter of the packaging shell of 5.4mm, the inner diameter of 0.8mm and the length of 15mm. It is sintered at 1500℃ for 2 hours and then polished after cooling to ensure that the hardness is ≥HRC70. The oxygen-free copper inner layer 302 is deposited on the inner wall of the ceramic shell with a thickness of 0.1 mm by electroplating, the electroplating current density is controlled at 2A / dm², and the electroplating time is 30 minutes.

[0030] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art, based on their understanding of the technical solution and spirit of the present invention, can make various modifications, equivalent substitutions, or improvements, but all such changes fall within the scope of protection of the present invention. The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the principles of the present invention should be included within the scope of the claims of the present invention.

[0031] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. All should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0032] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A miniature fiber optic probe sensor for in-situ monitoring of acoustic emission intensity, characterized in that: The miniature fiber optic probe sensor includes: Optical fiber, used for transmitting optical signals; the optical fiber includes at least one core and at least one cladding; Ultraviolet-visible light detectors are used to convert optical signals into quantifiable electrical signals; Pressure-resistant enclosure, used for structural pressure-resistant support in high-pressure environments and as an isolation and protective layer against highly corrosive media.

2. The miniature fiber optic probe sensor according to claim 1, characterized in that: The pressure-resistant encapsulation shell includes at least an outer shell and an inner layer, and both the outer shell and the inner layer are formed by an integral molding process. The outer shell is made of alumina ceramic material, and the inner layer is a composite oxygen-free copper metal layer.

3. The miniature fiber optic probe sensor according to claim 1, characterized in that: The fiber end is designed with a tapered structure, and the sidewalls are polished to reduce light scattering. The tapered probe end of the fiber extends 1.2-2mm beyond the front end of the pressure-resistant encapsulation shell.

4. The miniature fiber optic probe sensor according to claim 3, characterized in that: The cone-shaped structure has a vertices angle of 60° and a sidewall roughness Ra≤0.1μm after polishing.

5. The miniature fiber optic probe sensor according to claim 4, characterized in that: The optical fiber and the pressure-resistant encapsulation shell are provided with a guide hole at the front end and an outlet channel at the rear end. The interface of the guide hole and the outlet channel are filled with high-pressure resistant silicone sealant with a thickness of 0.1 mm.

6. The miniature fiber optic probe sensor according to claim 5, characterized in that: The high-pressure resistant silicone sealant adopts a segmented curing process, that is, it is cured at room temperature for 2 hours, and then cured at 80°C for 1 hour to ensure that the sealing gap is ≤0.01mm.

7. The miniature fiber optic probe sensor according to claim 1, characterized in that: The fiber core is made of quartz material and is a single-mode optical fiber with a diameter of 8μm and a refractive index of 1.46±0.

002.

8. The miniature fiber optic probe sensor according to claim 7, characterized in that: The ends of the fiber core are rounded with a radius of 0.5mm and the surface is passivated.

9. The miniature fiber optic probe sensor according to claim 8, characterized in that: The passivation treatment is performed by using a chromate passivation process to passivate the surface of the fiber core.

10. The miniature fiber optic probe sensor according to claim 7, characterized in that: The spectral response range of the ultraviolet-visible detector is 200nm-760nm.

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