Interferometric optical fiber sensor, optical fiber probe, and method of detection of chemical substance

Abstract

To apply in large amounts of reproducible testing and examination.SOLUTION: An interferometric optical fiber sensor for detecting chemical substances comprises a light source, a detector, an optical path arranged between the light source and the detector, a light dividing element to which the detector and the light source are connected, an optical fiber segment, and includes a measuring element constituting a resonant cavity and having a surface configured to come into contact with a chemical substance to be detected. The optical fiber segment and the measuring element are squeezed together so that there is only a residual cavity between them and the optical fiber segment is at least along part of its length contained within a capillary, a first end portion of the capillary is joined with the measuring element while the other portion of the capillary is clenched on the optical fiber segment, thereby the capillary, the optical fiber segment, and the measuring element constitute together an optical fiber measuring probe which is part of the optical path, the capillary has a length of at least 5 mm.SELECTED DRAWING: Figure 1a

Description

[Technical field]

[0001] The present invention relates to an interferometric optical fiber sensor, an optical fiber probe, and a method for detecting the optical fiber probe. The present invention relates to a method for detecting chemicals using an interferometric fiber optic sensor. [Background technology]

[0002] Interferometric fiber optic sensors for measuring parameters such as temperature, strain or material detection are used. It is known in the art.

[0003] International Patent Application Publication No. WO2018106134 describes a method for detecting a substance that interacts with the substance to be detected. The interferometer includes a Michelson interferometer having one arm covered with an active material configured to The result of this interaction is a measure of the thickness or thickness of the active material. The change in optical thickness, refractive index or attenuation at the end of the measurement arm. A fiber optic sensor can be used to detect the presence of a substance in the environment surrounding the measurement arm. In particular, the measuring arm is immersed in an unknown substance and the substance is detected by one or more predefined It is possible to detect whether the substance contains an active substance. or a group of substances to be detected. It consists of observing the interference fringes before contact with the unknown substance and after contact with either the environment or the unknown substance. The presence of a predefined substance is detected when a specific shift in the interference fringes is detected.

[0004] Other configurations of interferometric sensors are known in the art. It is one of the so-called multi-beam interferometers, which are used to inspect light waves and have two parallel It utilizes the phenomenon of multiple reflections of a light beam between partially transparent mirrors.

[0005] An example of such a structure is EP3054272, which may serve as an example. The fuel level sensor disclosed in the description of the present invention, wherein the optical cavity is made of a semiconductor material, e.g. The optical fiber is fabricated from gallium arsenide. The optical cavity is located on the underside of the diaphragm. The change in dimensions resulting from the change in pressure of the diaphragm on the cavity causes The results can then be interpreted as the state of the fuel reserve.

[0006] US Patent Application Publication No. 2005254062 discloses a method for detecting the presence, amount, or rate of binding of an analyte. The present invention discloses an interferometric sensor and method for detecting a lattice pattern. The sensor functions in a Fabry-Perot configuration. The optical path between the light source and the detector includes a light splitting element and a measuring element probe. The optical fiber transmits light through the gap to the first and second optical elements. The detector is coated with a substance capable of binding the analyte. The analyte changes the spectrum of the reflected light. Documents are analyzed by observing and observing specific substances (analytes, especially antigens). This disclosure is not without its shortcomings. This requires high precision in the manufacture of the first and second optical elements and in particular a precise definition of the gap. It is important that the probe is repeatable and that spectral changes are properly observed. It is a non-optional requirement, which comes at the cost of complicating the mathematical model. Replacing the probe is also a problem, as is its manufacture. Summary of the Invention

[0007] Sensors known in the art are difficult to mass produce and have parameters that are difficult to reproduce. On the other hand, it is difficult to measure the amount of sample, and it is a little difficult to handle with small samples. Sensors provide only limited information about the specific conditions that are met. There is a need for a sensor that can be applied to a large number of reproducible tests and inspections. The objective is to develop interferometric optical fiber sensors, optical fiber probes, etc., which do not have the drawbacks of the above-mentioned state-of-the-art technologies. and a method for using the same.

[0008] The present invention relates to an interferometric optical fiber sensor for detecting chemical substances, comprising a light source, a detector, and a The interferometric fiber optic sensor further includes a detector. The optical splitting element and the optical fiber segment to which the detector and the light source are connected constitute a resonant cavity. and a measuring element having a surface configured to contact the chemical to be detected. The optical fiber segment and the measurement element are arranged such that there is only a residual cavity between them. The optical fiber segments are pushed together like a The first end of the capillary is connected to the measuring element and is contained within the capillary. Meanwhile, the other part of the capillary is clamped onto the optical fiber segment, resulting in The pirali, the optical fiber segment, and the measurement element together are part of the optical fiber path. The length of the capillary is at least 5 mm. A positive consequence of such a structure is that residual cavities can be neglected in the calculations. This has a low impact on the measurement results and facilitates manufacturing in a stable and reproducible manner. The length of the capillary ensures that the residual cavity parameters are not affected by the process. The clamping point on the optical fiber segment should be located far enough away from the residual cavity so as not to As a result, the sensor according to the invention is constituted by the surface of the face of the measuring element. It can be considered as having a single measurement resonant cavity. The probe with the capillary can be cut and replaced with a new one. Easily replaceable by welding or using fiber optic connectors The sensor can detect, among other things, acetone, refrigerants, ethanol vapor, hydrochloric acid, poly(aryl) of the group including arylamine hydrochloride, arylamine, proteins, biomarkers, and antigens An additional advantage of the present invention is that it can be used to detect, but not limited to, substances. The object of this configuration is to have the material emitted by the optical fiber interact with the face of the measurement element in front of it. This configuration is in contrast to probes where the material being detected interacts with the side of the optical fiber or measuring element. to improve measurement dynamics.

[0009] Advantageously, the ratio of the optical length a × n1 of the residual cavity to the optical length b × n2 of the measurement element is between 0 and The ratio of the length of the resonant cavity to the length of the residual cavity is in the range of 0 to 0.4. This ratio allows the analysis to be simplified by increasing the frequency of the interference fringes. It is easier to use the single cavity model. The spectrum is the spectrum of the measurement signal resulting from the cavity formed by the measurement element. In the mathematical model, it is the sum of two sinusoidal signals with different periods. By defining a given ratio, the spectrum resulting from the residual cavity It becomes easier to treat the effect on as constant and ignore it.

[0010] Advantageously, the measuring element is at least partially covered with a substance that is adhesive to the substance to be detected. This configuration makes it easy to capture a sample of the substance to be detected. become.

[0011] Alternatively, the measuring element may be at least one material that loses adhesion when exposed to the substance to be detected. In this configuration, the measuring element is placed on a predefined material. It is possible to detect the result of exposure of the surface and, consequently, the substance itself.

[0012] Alternatively, the measurement element may be an object that changes an optical parameter when exposed to the substance to be detected. Each of the specific substances to be detected and each of the interactions By applying a cover with multiple substances that interact with each other, one can measure one It is possible to detect a large number of substances in a single measurement. The change in the parameters of the substance or the element itself after exposure to an external factor is By changing the length of the optical path of the interferometer, a shift in the interference fringes can be observed. do.

[0013] The measuring element is preferably made of glass, quartz glass SiO2, lead glass, ZBLAN glass, and a polymer.

[0014] The optical fiber segment is preferably a single mode fiber within the operating range of the detector. .

[0015] The end of the optical fiber segment inside the capillary is advantageously beveled to allow the optical fiber to pass through the capillary. The angle is in the range of 4° to 20° with respect to the axis of the fiber segment. Results were obtained in the range of 7° to 8°.

[0016] A first surface of the optical fiber segment that confines the residual cavity from a first side has a reflectivity R1, and the second surface of the measurement element, which confines the residual cavity from the opposite side, has a reflectance R2 and the reflectance advantageously satisfies the following conditions:

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[0017] Advantageously, the optical fiber segment is a multi-core fiber segment, the optical fiber segment including in the optical path The interferometer is connected to a fan-in / fan-out device via a first optical splitting element. a first light source and a first detector connected to a fan-in / fan-out device; a second light source connected to the fan-in / fan-out device via a light splitting element; This configuration allows the shifts at different wavelengths to be observed simultaneously. and to improve the sensitivity and specificity of detection, or to detect two different substances simultaneously. It becomes possible.

[0018] Advantageously, the interferometer is coupled to a fan-in / fan-out device via a third optical splitting element. A third light source and a third detector are connected to the third light source. The application of sources and detectors further improves the sensitivity and specificity, but still the sensor This leads to a high degree of complexity.

[0019] Advantageously, the at least one light source is selected from the group comprising: Supercontinuum light source, Halogen lamps emitting light in the wavelength range of 400-700 nm, A superluminescent diode with a central wavelength of 1310 nm, A superluminescent diode with a central wavelength of 1400 nm, A superluminescent diode with a central wavelength of 1450 nm, A superluminescent diode with a central wavelength of 1550 nm, -Center wavelength in the range of 1310~1550nm, tunable within a range of 20nm or more A versatile narrowband light source.

[0020] Generally, good results are obtained with light sources operating in the wavelength range of 400-1600 nm. The light source and the mechanism of interaction of the substance to be detected with the surface of the measuring element are selected. It is easy to select the length of the measuring element to obtain fringes at the desired wavelength corresponding to the selected light source. As a result, the shift in the interference fringes can be easily observed.

[0021] The fiber optic measurement probe according to the present invention comprises an optical fiber segment and a probe in contact with the material. and a measurement element having a surface, the optical fiber segment and the measurement element remaining therebetween. The optical fiber segments are packed together so that there is only a cavity. The first end of the capillary is the measurement area, and the second end of the capillary is the measurement area. The other part of the capillary is clamped onto the optical fiber segment. The probe according to the invention can be placed far away from the light source and the detector. It can be easily replaced. It can be easily sterilized and made suitable for subsequent use. We can respond to your request.

[0022] Advantageously, the ratio of the optical length a × n1 of the residual cavity to the optical length b × n2 of the measurement element is between 0 and The ratio of the length of the resonant cavity to the length of the residual cavity is in the range of 0 to 0.4. This ratio allows the analysis to be simplified by increasing the frequency of the interference fringes. It is easier to use a single cavity model. The measurement fringes are generated from the residual cavity. It is much narrower than the one you would see.

[0023] Advantageously, the measuring element is at least partially covered with a substance that is adhesive to the substance to be detected. This configuration makes it easy to capture a sample of the substance to be detected. It becomes easier.

[0024] Alternatively, the measuring element may be at least one material that loses adhesion when exposed to the substance to be detected. In this configuration, the measuring element is placed on a predefined material. It is possible to detect the result of exposure of the surface and, consequently, the substance itself.

[0025] Alternatively, the measurement element may be an object that changes an optical parameter when exposed to the substance to be detected. Each of the sensors has a surface at least partially covered with a substance. By applying a cover with multiple interacting substances, the same detector and light source can be used It is possible to detect many substances in one measurement. Changes in the parameters of the above substances or the parameters of the elements themselves after exposure to external factors By changing the length of the optical path of the interferometer, a shift in the interference fringes can be observed. Cut.

[0026] The measuring element is preferably made of glass, quartz glass, lead glass, ZBLAN glass, and polysilicon. The tiles are made of a material containing a substance selected from the group including mer.

[0027] The end of the optical fiber segment inside the capillary is advantageously beveled to allow the optical fiber to pass through the capillary. It is tilted at an angle in the range of 4° to 20° with respect to the axis of the fiber segment.

[0028] A first surface of the optical fiber segment that confines the residual cavity from a first side has a reflectivity R1, and the second surface of the measurement element, which confines the residual cavity from the opposite side, has a reflectance R2 and the reflectance advantageously satisfies the following conditions:

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[0029] Advantageously, between the refractive index n1 of the medium in the capillary and the refractive index n2 of the material of the measuring element The difference is greater than 30%, i.e.

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[0030] The optical fiber measuring probe preferably has an optical fiber on the side opposite to the side on which the measuring element is arranged. There are connectors on the ends of the fiber segments.

[0031] Advantageously, the optical fiber segment of the measurement probe has two or more cores. , allowing the probe to be used in an interferometer having multiple detectors and / or light sources, This provides better sensitivity and specificity.

[0032] The optical fiber measuring probe includes a detector, a light source, and an optical fiber measuring probe. The method of detecting chemicals using an interferometer according to the present invention involves directing light to a substance to be detected by a predetermined A substance is considered to be detected when a shift in the defined interference pattern is observed on the detector. The measuring element constitutes a resonant cavity, which allows the display of interference fringes in the wavelength domain. If material is attached to the exterior surface of the cavity or has already been attached If the thickness of the material is increased, the interference fringes shift to longer wavelengths. The magnitude of the shift is used to Alternatively, if a layer is delaminated, the interference fringes become shorter. By moving towards the wavelength side, the decrease in thickness can be determined.

[0033] Embodiments of the present invention are described in detail below with reference to the following figures. [Brief description of the drawings]

[0034] [Figure 1a] FIG. 1 is a block diagram of an interferometric optical fiber sensor according to first, second and third embodiments of the present invention; [Figure 1b] FIG. 2 is a diagram illustrating a schematic configuration of a probe according to an embodiment of the present invention. [Figure 1c] FIG. 13 is a schematic diagram illustrating a probe configuration according to another embodiment of the present invention. [Figure 1d] FIG. 13 is a schematic diagram illustrating a probe configuration according to yet another embodiment of the present invention. [Figure 2a] FIG. 2 illustrates the shift in interference fringes upon exposure to a substance under test in a first embodiment of the present invention. [Figure 2b] FIG. 2 illustrates the shift in interference fringes upon exposure to a substance under test in a first embodiment of the present invention. [Diagram 3] FIG. 11 is a block diagram of a sensor according to a fourth embodiment of the present invention using a multi-core (3-core) fiber. [Figure 4] This is a cross-sectional view of this three-core fiber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] [Example 1] A block diagram of the interferometer of this embodiment is presented in FIG. A superluminescent diode with a central wavelength of 0 nm and a full width at half maximum equal to 50 nm. The first port of the circulator constituting the splitting element 3 is connected to the second port of the circulator by a single mode optical fiber. A measuring probe 13 according to the invention is connected to the second circulator port C.1. C.2 is connected to the end of a single-mode optical fiber (optical fiber segment) 4. In the structure of the measurement probe 13, the other end of the optical fiber 4 is connected to a quartz glass capillary. A measuring element enclosed within the capillary 11 and attached to the capillary 11 by splicing. It is forced upon 5.

[0036] Alternatively, the capillary may be clamped to the measuring element 5 .

[0037] The end of the optical fiber 4 inside the capillary is cut at an angle α=8°, so that Between the end of the optical fiber 4 and the measuring element 5, a residual having an effective width of a=0 μm to a=2 μm is provided. There is a gap which forms a retention cavity 7. The length of the measuring element 5 is 20 μm.

[0038] Further testing has shown that the effect of attenuating the reflected signal is consistent across the full range of cut angles from 4° to 20°. It has been shown that it is possible to obtain a certain degree of

[0039] At the third port C.3 of the circulator, used as detector 2 in this embodiment of the invention, An optical spectrum analyzer that is connected to the oscilloscope is also connected.

[0040] Light from a light source 1 passes through a circulator constituting a splitting element 3 and reaches an optical fiber 4. and passes through a gap of width "a" to a measuring element 5 having a surface 6. A Fabry-Perot interferometer is obtained. Detector 2 observes the interference fringes in the spectral domain. The fringes and / or contrast shifts can be attributed to cavities formed along the optical path. In practice, the surface 6 of the measuring element 5 and the opposite surface of the measuring element 5 are The change in the surface of the cavity boundary established between the ends of the cavity is useful for the measurement. The best results are obtained when only one cavity is included. Each connection and each boundary of the medium , an additional cavity is introduced. In the structure of the interferometer according to the invention, the number of cavities is limited. The residual cavity 7 is negligible due to its small size. By cutting the ends of the cavity in an oblique manner and providing a suitable ratio of reflectances at the boundaries of the cavity, the measurement results Contributions to are limited.

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[0041] The measuring elements 5 are tiles in the form of glass cylinders with a height of 20 μm. Face 6 of 5 is coated with a perfluorinated polymer having a refractive index of about 1.33. This is done by immersing the measuring element 5 in the polymer solution. Detected substances that are compounds of carbon, chlorine, and fluorine, such as 1,2,2-trifluoroethane As a result of exposing the surface 6 to a substance (refrigerant), the layer of polymer swells. In this configuration, the swelling is , which contributes to a 10 nm change in material thickness, which is 0.6 nm away from the 1410 nm Shift of interference fringes (showing reflectance S11 as a function of wavelength before and after exposure of the measurement element to the refrigerant) 2a and 2b).

[0042] Based on the obtained spectral plots shown in Figs. 2a and 2b, the surface 6 At the same time, the thickness of the layer that changes thickness is determined.

[0043] The first step is to determine the difference in wavelength between adjacent interference fringes during the measurement before exposure to the measurement substance. The objective of the present invention is to measure the thickness of the measuring element 5 by measuring the thickness of the measuring element 5. Therefore, the calibration of the interferometer determines the difference in the optical path of the interferometer and the surface of the measurement element 5. Considering the refractive index of the cavity formed by this, the optical signal passes through the cavity twice. This is done by taking into account:

[0044] Next, surface 6 is exposed to a substance to be measured and one of the interference fringes is analyzed. The difference in wavelength corresponding to is determined. FIG. 2b shows the stripes before and after exposure. A shift in the fringes occurred due to the change in thickness of the layer attached to the

[0045] After determining the difference in wavelength corresponding to said interference fringes before and after exposure, the layer covering the surface 6 of the measuring element 5 is Knowing the refractive index of , the change in layer thickness ΔL is calculated by the following formula:

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[0046] When the change in wavelength Δλ of the interference fringes is in the long wavelength range (0.1 nm, 16.8 nm), Detection of the refrigerant is observed. This range was selected experimentally. In another embodiment of the present invention Other ranges and other active substances are suitable for selection to detect other substances. This can be done with routine testing. Those skilled in the art will readily suggest other active substances and will be able to determine the appropriate range of active substances. The range can be measured.

[0047] In this embodiment, the configuration of the measurement probe 13 according to the invention allows for a residual optical cavity 7 can be effectively shortened. The measurement probe 13 is shown diagrammatically in FIG. The end of the optical fiber 4 and the measuring element 5 are connected to a glass capillary having a U-section. The end of the optical fiber 4 is cut at an angle of 20° and pressed against the measuring element 5. The capillary is secured by welding at both ends, the measuring element 5 and the optical fiber 4. The connection point between the capillary 11 and the optical fiber 4 is sealed to prevent accidental increase in the reflection of one of the layers. To prevent this, it should be far away from the residual optical cavity 7. This is This was achieved using a 11 mm long capillary.

[0048] [Example 2] An interferometer according to a second embodiment of the invention is constructed according to the same block diagram shown in FIG. Light source 1 is a narrowband laser with a center wavelength of 1550 nm and a tunable range of 50 nm. The light source 1 is a tunable light source. It is connected to the first output of the circulator via a single mode fiber. The measurement probe 13 is connected to the second port C. 2 is connected.

[0049] A measurement probe according to this embodiment of the invention is shown diagrammatically in FIG. The optics are interconnected in the optical path of the interferometer, and the end of a single-mode optical fiber 4 is connected to the optics shown in the figure. The other end of the optical fiber 4 is connected to a capillary 11. The end of the optical fiber 4, housed in a capillary, is surrounded and pressed against the measuring element 5. The capillary 11 is cut at an angle of 8°. A weld is made between the capillary 11 and the measuring element 5. As a result, a residual cavity 7 with an effective width a=2 μm is formed between the end of the optical fiber 4 and the measurement element 5. The length of the measuring element 5 is b=20 μm. 6 is covered with the same material as in Example 1.

[0050] Detector 2 is connected to the third port C.3 of the circulator.

[0051] [Example 3] The block diagram of the interferometer according to the third embodiment of the present invention is the same as that of the first and second embodiments. This is shown in Figure 1a. It emits light in the wavelength range of 400 μm to 700 μm. The light source 1, a halogen lamp, is fed into a birefringent optical fiber (polarized light and (maintaining single mode) is connected to the first port C.1 of the circulator. The polarization-maintaining circulator has the function of a splitting element 3. The second The port C.2 is connected to the measurement probe (13). Segment 4 is birefringent and has a beat length of 3 mm at wavelength λ=550 nm. It is polarization-maintaining and single-mode in the wavelength operating band of the light source 1. The measurement element (5) is It is made of lead glass having a refractive index equal to .8. The third port of the circulator, C. 3 is connected to a spectrometer that constitutes the detector 2 .

[0052] The measurement probe 13, shown diagrammatically in FIG. 1d, has an O-shaped cross section and a length of 5 mm. The capillary 11 includes a segment of a polarization-maintaining optical fiber 4 and a lead-gas A measuring element 5 made of glass and having a length of b=200 μm is inserted. The resulting residual cavity 7 has a length a=0.1 μm.

[0053] Alternatively, the measuring element 5 may be made of glass, quartz glass, lead glass, etc., which also have relatively low losses. It can be made of ZBLAN glass and other materials selected from the group including polymers. do.

[0054] Quartz glass is particularly convenient for processing. It can be used to cut the wire into desired lengths and To produce a cylindrical measuring element 5 having a smooth surface and a base which are parallel to one another and perpendicular to the axis. It is convenient to do so.

[0055] The substance to be detected is deposited on the surface 6 of the measuring element 5 by a piranha solution, i.e. in a volume ratio of 3:1. The solution was obtained by placing surface 6 in a solution containing concentrated sulfuric acid and 30% hydrogen peroxide mixed at 100°C. The surface 6 thus treated is sufficiently active to be exposed to poly(allylamine hydrochloride). When the sample was covered with a layer of polymer with a refractive index of 1.5 and a thickness of 2 nm, can be.

[0056] The surface of lead glass has chemical bonds O-Si-O-Si-O. When exposed to piranha solution, After this, the structure Si-O-Si is transformed into the more polar 2xSi-OH, resulting in the The ionic polymer adheres to the surface more easily.

[0057] A layer of 2 nm of material having a refractive index of 1.5 on the surface 6 of the measuring element 5 is This results in a shift in the spectral refractive fringes of 5 pm in wavelength. The sensor can be applied to detect poly(allylamine hydrochloride), the presence of which is detected by spectrophotometry. It is observed when the spectrum fringes are shifted to longer wavelengths by a value between 2 pm and 0.2 nm. do.

[0058] [Example 4] A block diagram of a fourth embodiment of the invention is shown in FIG. By using a measuring probe 9 with a section, the spectrum of different wavelengths of the light source can be In this example, a three-core optical fiber is shown in cross section in FIG. Schematically, a set of three light sources is shown.

[0059] The set of light sources (1.1, 1.2, 1.3) are 1310nm, 1450nm, respectively. Three broad spectrum superluminescence sources with wavelengths of 1500 nm and 1550 nm, and a full width of 50 nm. The light sources were each connected to a circulator in a reflectance measurement configuration. Connected to detectors 2.1, 2.2, 2.3 connected to it via 3.1, 3.2, 3.3 Spectrometers were used as detectors 2.1, 2.2, and 2.3. The free ports of the regulators 3.1, 3.2, and 3.3 are fan-in / fan-out devices. 8 ports, which are connected to the three-core section of the optical fiber 4 of the measurement probe 9. The core of the MOSFET is connected to the

[0060] The measuring element 5 has a length b=50 μm and is made of glass ZBLAN (ZrF4-BaF2-L The input multi-core optical fiber is made of ZBLAN glass. Between the electrode 4 and the electrode 5, there is a gap (a residual cavity 7 with a length a = 1 μm). A Fabry-Perot cavity is formed for each of the cores 9.1, 9.2, 9.3.

[0061] The surface 6 of the measuring element 5 is the result of immersion in a 1% solution of polystyrene in dichloromethane. The active layer remaining on face 6 after drying has specific properties. and swells as a result of contact with acetone. The sensor according to the invention can be used as an acetone sensor.

[0062] Those skilled in the art will appreciate that the sensor of the present invention can detect and measure desired substances at 1300 nm. Other mid-wavelength and spectral width light sources that allow measurements in the ~1500nm range Other sets of sources can easily be provided.

[0063] Light from the light source passing through a single mode optical fiber enters a circulator 3 and then a fan-in 3. The optical fiber is then guided to a 3-core / fan-out device 8 and then to an input 3-core optical fiber 4. The bar has a triangular cross section and a lattice set from the cores 9.1, 9.2, and 9.3 shown in FIG. The cores 9.1, 9.2, and 9.3 have a diameter of 8.2 μm and a thickness of 0. From the optical fiber 4, light passes through the air-filled residual cavity 7 and the measurement object. The light reflected from the edge of the measuring element is guided to the optical fiber segment 4. , through the fan-in / fan-out element, through the single mode optical fiber and the circulator. 5 and back to the detector, where it is reflected by the opposite ends of the measuring element 5. The interference fringes resulting from the interference are observed. The measurement probe is immersed in acetone at room temperature. The thickness of the layer changes by about 200 nm, and the interference fringes are about 60 nm around the wavelength of 1550 nm. .4nm, 6nm near the 1450nm wavelength, and about 5. The interference fringe shift obtained for all light source wavelengths was 0.1 nm to 8.0 nm. It is recognized that acetone has been detected when the concentration is within the range of 1 nm. An increase in the specificity of the extraction method was achieved.

[0064] The use of fan-in / fan-out elements allows the shifting of all of these fringes simultaneously. Observing the two interference fringes allows for the improvement of the sensor's operation (higher Sensitivity and specificity have already been achieved. Some detection materials have faber with four or more cores. It is possible to use a single driver and a correspondingly large number of light sources (up to 10, 12 or more). desirable.

[0065] In an embodiment of the sensor according to the invention, a multicore fiber section having a large number of cores is Such a sensor system can use a number of light sources and detectors. The systems and measurement probes are more complex but offer the potential for more reliable identification of the detected material. Glass.

[0066] In some embodiments of the present invention, optical fiber sections are used as measurement elements 5. By using an optical fiber segment as the measuring element 5, the Diffraction is avoided (because the core is inside the optical fiber) Positive dispersion within the source bandwidth By using an optical fiber having the above structure, the occurrence of nonlinear phenomena can be avoided.

[0067] Those skilled in the art will recognize that in some circumstances other advantageous variations in the optical path between the light source and the detector may be possible. Generally, but without departing from the invention as defined by the claims, For example, the circulator used in the above embodiment can be a coupler and a Can be easily replaced.

[0068] Likewise, those skilled in the art, having been familiar with the above description, will be able to easily adapt the surface 6 of the measuring element 5 to various detection substances. It is easy to propose various methods of coating or sensitizing the light source and the appropriate optical parameters of the light path. The sensitivity to hydrochloric acid is improved by a small porosity and a pH of about 1.8. A measuring element made of quartz glass having a refractive index is prepared, and its surface is coated with yttrium oxide. For example, yttrium oxide is deposited on the glass by laser heating. By contacting the analytical element with hydrochloric acid, interference fringes at 1550 nm are formed. There is a shift in wavelength of about 4 nm.

[0069] Those skilled in the art will also recognize that, inter alia, by splicing fibers and by using dedicated optical fiber Various techniques can be proposed for connecting the measurement probe to the optical path using a connector.

[0070] Those skilled in the art will readily be able to select the length of the measurement element to match the light source band and the light source described herein. Various alternatives can be substituted. The inventors have also found that various light sources, including: has been used successfully. Supercontinuum light source, Halogen lamps emitting light from the range of 400-700 nm, -Superluminescent diode with a central wavelength of 1310 nm, -Superluminescent diode with a central wavelength of 1400 nm, -Superluminescent diode with a central wavelength of 1450 nm, -Superluminescent diode with a central wavelength of 1550 nm, -Center wavelength in the range of 1310~1550nm, tunable within a range of 20nm or more A versatile narrowband light source.

[0071] The present invention can be implemented using a variety of measurement techniques known to those skilled in the art. Use a broadband light source such as a SLED diode, supercontinuum light source, or halogen. It is possible to use a spectrum analyzer or spectrometer as a detector. Alternatively, one tunable light source can be used and switched to the next wavelength during the measurement. In this configuration, a simpler detector can be used. It is possible to analyze one broadband optical signal using several detectors, or to use one broadband detector. A single broadband optical signal is analyzed using several narrowband light sources for analysis by a detector. There is a possibility that.

[0072] The embodiments are to be read as illustrating but not limiting the invention. It should be.

Claims

1. A light source (1, 1.1, 1.2, 1.3), a detector (2, 2.1, 2.2, 2.3), and The light source (1, 1.1, 1.2, 1.3) and the detector (2, 2.1, 2.2, 2.3) and a light path arranged between the detectors (2, 2.1, 2.2, 2.3), ) and the light source (1, 1.1, 1.2, 1.3) are connected to the light dividing element (3, 3.1, 3.2, 3.3) and an optical fiber segment (4) are used to form a resonant cavity and to detect The measuring element (5) has a surface (6) configured to contact the chemical substance dispensed.

1. An interferometric optical fiber sensor for detecting a chemical substance, comprising: The optical fiber segment (4) and the measuring element (5) are arranged with a residual cavity therebetween. The optical fiber segments (4) are pressed together so that no gap (7) exists between them. ) is contained within a capillary (11) along at least a portion of its length, said capillary A first end portion of the capillary (11) is connected to the measuring element (5), while a second end portion of the capillary ( The other part of the optical fiber segment (4) is then clamped onto the optical fiber segment (11). The capillary (11), the optical fiber segment (4) and the measuring element (5) are connected together. The optical fiber measuring probe (13) is a part of the optical path, and the capillary ( 11) An interferometric optical fiber sensor having a length of at least 5 mm.

2. The optical length of the residual cavity (7) is a×n １ and the optical length b×n of the measuring element (5) ２ of 2. The interferometer of claim 1, wherein the ratio is in the range 0 to 0.

4.

3. The measuring element (5) is at least partially bound by a substance that is adhesive to the substance to be detected.

3. An interferometer as claimed in claim 1 or 2, characterized in that the surface (6) is covered with

4. The measuring element (5) is at least one material that loses adhesion when exposed to the substance to be detected.

3. An interference device according to claim 1 or 2, characterized in that the surface (6) is also partially covered. Total.

5. The measuring element (5) changes an optical parameter when exposed to the substance to be detected.

3. The method according to claim 1, further comprising the step of:

4. An interferometer as defined in claim 3.

6. The measuring element (5) is made of glass, quartz glass, lead glass, ZBLAN glass, and poly The tile is made of a material containing a substance selected from the group including mer. An interferometer according to any one of claims 1 to 5.

7. The optical fiber segment (4) is a single mode fiber within the operating range of the detector (2).

7. The interferometer according to claim 1, wherein the interferometer is a detector.

8. The end of the optical fiber segment (4) inside the capillary (11) is beveled. and at an angle in the range of 4° to 20° with respect to the axis of the optical fiber segment (4). An interferometer according to any one of claims 1 to 7, characterized in that it is tilted.

9. A first portion of the optical fiber segment (4) that confines the residual cavity from a first side. The surface of the reflectance R １ and the measuring element ( 5) The second surface has a reflectance R ２ and the reflectance satisfies the following conditions: [0010] 9. The interferometer according to claim 8, wherein the following is satisfied:

10. The optical fiber segment (4) is a multi-core fiber segment, and the optical path a first optical splitting element (8) connected to a fan-in / fan-out (8) in the A first optical fiber connected to the fan-in / fan-out device (8) via (3.1) a source (1.1) and a first detector (2.1) and a second light splitting element (3.2) A second light source (1.2) and a second light source (1.3) connected to the fan-in / fan-out device (8).

10. The interference detector according to claim 1, further comprising a detector (2.2). Total.

11. The interferometer is coupled to the fan-in / fan-out detector via a third optical splitting element (3.3). a third light source (1.3) and a third detector (2.3) connected to the device (8).

11. The interferometer of claim 10,

12. The interferometer, ・Supercontinuum light source, - halogen lamps emitting light in the wavelength range of 400-700 nm; - a superluminescent diode with a central wavelength of 1310 nm; - a superluminescent diode with a central wavelength of 1400 nm; - a superluminescent diode with a central wavelength of 1450 nm; - a superluminescent diode with a central wavelength of 1550 nm; - Center wavelength in the range of 1310-1550 nm, adjustable within a range of 20 nm or more A narrowband light source At least one light source (1, 1.1, 1.2, 1.3) selected from the group including An interferometer according to any one of claims 1 to 11.

13. An optical fiber comprising an optical fiber segment (4) and a measuring element (5) having a surface (6). A measurement probe comprising: The optical fiber segment (4) and the measuring element (5) are arranged with a residual cavity therebetween. The optical fiber segments (4) are pressed together so that no gap (7) exists between them. ) is contained within a capillary (11) along at least a portion of its length, said capillary A first end portion of the capillary (11) is connected to the measuring element (5), while the first end portion of the capillary (11) is connected to the measuring element (5). the other part of the optical fiber segment (4) is clamped onto the optical fiber segment (4). Fiber optic measurement probe.

14. The optical length of the residual cavity (7) is a×n １ and the optical length b×n of the measuring element (5) ２ of The optical fiber measurement probe according to claim 13, characterized in that the ratio is in the range of 0 to 0.

4. -ve.

15. The measuring element (5) is at least partially bound by a substance that is adhesive to the substance to be detected.

15. An optical fiber according to claim 13 or 14, characterized in that the face (6) is covered with Measurement probe.

16. The measuring element (5) is at least one material that loses adhesion when exposed to the substance to be detected.

15. The method according to claim 13 or 14, characterized in that the surface (6) is also partially covered. Fiber optic measurement probe.

17. The measuring element (5) changes an optical parameter when exposed to the substance to be detected.

2. The method according to claim 1, further comprising the step of:

15. The optical fiber measurement probe according to claim 3 or 14.

18. The measuring element (5) is made of glass, quartz glass, lead glass, ZBLAN glass, and poly The tile is made of a material containing a substance selected from the group including mer. An optical fiber measurement probe according to any one of claims 13 to 17.

19. The end of the optical fiber segment (4) inside the capillary (11) is beveled. and is at an angle in the range of 4° to 20° with respect to the axis of the optical fiber segment (4). The optical fiber according to any one of claims 13 to 18, characterized in that it is tilted toward the optical fiber. Measuring probe.

20. said optical fiber segment (4) confining said residual cavity (7) from a first side; The reflectance R from the first surface １ and before sealing the remaining cavity (7) from the opposite side. The reflectance R from the second surface of the measurement element (5) ２ However, the following conditions are met: [0025] The optical fiber measurement profile according to any one of claims 13 to 19, characterized in that -ve.

21. The optical fiber measuring probe is arranged on the side opposite to the side on which the measuring element (5) is arranged. The optical fiber segment (4) has a connector provided at an end thereof. An optical fiber measurement probe according to any one of claims 13 to 20.

22. The optical fiber segment (4) has two or more cores (9.1, 9.2, 9.3). The optical fiber measurement probe according to any one of claims 13 to 20, 。

23. a light path, the light path including a detector, a light source, and a fiber optic measurement probe; The interferometer optical fiber according to any one of claims 1 to 12, which is an interferometer for directing light to a detection substance. A method for detecting a chemical substance using a fiber sensor, comprising: the substance is deemed to be detected when a sample is observed on the detector. method.

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