Measuring device with an optical connecting fiber and a measuring instrument for the instrumentation of an aeronautical system, as well as an aeronautical system containing such a measuring instrument.

Description

technical field

[0001] The invention relates to the field of measuring equipment and its optical connection to optical measuring systems.

[0002] The invention thus relates more particularly to a measuring device, a measuring assembly and an aeronautical apparatus comprising such a measuring device. Prior state of the art

[0003] To obtain a measurement of a parameter of a device or vehicle, such as the acoustic vibrations to which it is subjected, it is sometimes necessary to install measuring equipment, or sensors, such as acoustic vibration measuring devices, and corresponding measurement systems that allow these measuring devices to be interrogated to determine the parameter. When this communication is optical, it is generally carried out using an optical fiber.

[0004] We can thus cite the example provided by document FR 3 026 838 concerning the measurement of acoustic vibrations by means of an opto-mechanical transducer and which can be interrogated by an optical measurement system by means of a connection provided by an optical fiber.

[0005] We also know of documents US208259551A1, DE102016202662A1 and US2013301037A1 which are all prior art of the invention presented below.

[0006] However, if such equipment allows one or more parameters of said device or vehicle to be measured, the measurements they provide are not always complete and may be dependent on other parameters, such as the temperature of the equipment, to which the equipment does not give access.

[0007] Thus, it could be advantageous to be able to complement the measurement(s) offered by such equipment without requiring the addition of new equipment which, in addition to increasing the weight of the device or vehicle, would then have to be integrated into said device or vehicle. Description of the invention

[0008] The invention aims to solve the above problem and thus aims to provide a solution to complement the measurements offered by a measuring device optically connected to a measuring system without requiring additional measuring equipment and without disrupting communication between said device and the optical system.

[0009] The invention relates to a measuring device comprising: a measuring equipment configured to be optically interrogated by a measuring system by means of first optical signals in a first wavelength range, a connecting optical fiber comprising a first end connected to the measuring equipment and a second end intended to be connected to the measuring system, the connecting optical fiber comprising at least one first multimode optical core in the first wavelength range to transmit the first optical signals.

[0010] The optical connection fiber further includes a second single-mode optical core in a second wavelength range to transmit second optical signals in the second wavelength range, the optical connecting fiber comprising at least a first functionalized optical fiber portion adapted to present to the second wavelength range an optical characteristic varying with an environmental parameter of the optical connecting fiber, and the measuring device further comprising a coupling system associated with the second end of the optical connecting fiber, the coupling system comprising at least a first and a second optical output and being adapted to optically couple the first optical core with the first output and to optically couple the second optical core with the second output.

[0011] Thus, without adding any extra measuring equipment, it is possible to obtain a measurement of an environmental parameter of the optical fiber, and therefore of the measuring equipment, by measuring the optical characteristic using a second optical signal in the second wavelength range. Furthermore, this measurement is performed with reduced interference since the first and second optical signals are confined to the first and second optical cores, respectively. It should also be noted that, with such a configuration, it is possible to combine two types of measurements: one, based on measurements provided by the measuring equipment, using a multimode optical fiber, and the other, based on measurements obtained using the functionalized portion of the optical fiber, using a single-mode optical fiber.

[0012] The term "functionalized portion" should be understood, as used above and throughout the rest of this document, to mean that the first portion of the optical fiber exhibits a structural modification compared to the rest of the unfunctionalized optical fiber, providing sensitivity to an environmental parameter. Such a structural modification of the optical fiber may be related, for example, to the composition of this portion or one of its elements, such as the second optical core, the addition of a coating, the inscription of a structure, such as a Bragg grating, or a combination of two or more of these possibilities.

[0013] According to an advantageous embodiment of the invention, the first optical fiber may further comprise a second functionalized fiber portion, said second functionalized fiber portion being adapted to exhibit at the second wavelength range an optical characteristic varying with an environmental parameter of the connecting optical fiber identical or different from that of the first functionalized optical fiber portion.

[0014] According to this possibility, the second wavelength range may include a first and second sub-range of wavelengths joined or disjoined, the functionalized portion of fiber being adapted to present to the first sub-range of wavelengths the optical characteristic varying with said environmental parameter of the connecting optical fiber, the second functionalized portion of fiber being adapted to present to the second sub-range of wavelengths the optical characteristic varying with the environmental parameter of the connecting optical fiber identical or different from that of the first functionalized portion of optical fiber.

[0015] According to one possibility of the invention, the functionalization of the first portion of functionalized fiber can be adapted to limit leakage of the second optical signals to the first optical body.

[0016] In this way, with the confinement of the second optical core maintained over the entire length of the connecting optical fiber, the separation between the first and second signals is almost total, and it is therefore not necessary to filter out any part of the second signals that might have diffused into the first optical core during the interaction between the second optical signals and the first functionalized portion of fiber.

[0017] The coupling system can also be configured to, at the level of the first output, filter at least partially the second optical signals guided in the first optical core.

[0018] Such a coupling system makes it possible to limit, or even eliminate, the part of the second optical signals that could have possibly diffused with the first optical signals and thus limit the risks of interference during the analysis of the second optical signals by the optical measurement system.

[0019] The coupling system can also be configured to, at the level of the second output, filter at least partially the first optical signals guided in the second optical core.

[0020] The second end of the optical fiber connection may include the coupling system, the coupling system comprising a first optical fiber segment optically coupled to the first optical core and optically decoupled from the second optical core, and a second optical fiber segment optically coupled to the second optical core and optically decoupled from the first optical core, the first optical fiber segment comprising the first optical output, the second optical fiber segment comprising the second optical output, the coupling system preferably being a double-clad coupler.

[0021] Such a coupling system makes it possible to provide a particularly compact coupling system since it is included in the optical fiber.

[0022] Furthermore, it should be noted that in a double-clad coupler configuration, such as that described in US patent 8792757, it is possible to achieve optical coupling of the first optical core with only the first optical output and optical coupling of the second optical core with the second optical output. This provides effective separation between the first and second optical signals. The coupling system can be external to the second optical fiber, such as a splitter capable of separating the first and second optical signals and directing them to the first and second optical outputs, respectively.

[0023] Thus, it is possible to better control the separation between the first and second optical signals while ensuring a connection between the connecting optical fiber and the measurement system by means of suitable connectors, since obtained through the coupling system.

[0024] The first functionalized portion of optical fiber may include a Bragg grating inscribed in the second optical core.

[0025] Such functionalization of the optical connection fiber makes it possible to trace back to environmental parameters of the optical connection fiber, such as temperature and the stresses exerted on it.

[0026] The measuring equipment can be a vibration detection system, such as a diaphragm vibration detection system.

[0027] Such a vibration detection system makes it possible to measure the vibrations to which the equipment on which the measuring device is installed is subjected, using simple optical signals.

[0028] The invention further relates to a set of measurements comprising: a measuring device according to the invention, an optical measurement system configured to query the measuring equipment by means of first optical signals in the first wavelength range and to measure the optical characteristic of the first functionalized optical fiber portion by means of second optical signals in the second wavelength range, the optical measurement system being connected to the first and second optical outputs of the coupling system.

[0029] Such a measurement system offers the advantages inherent in the measurement device according to the invention.

[0030] The optical measurement system may include: a first optical source adapted to emit optical signals in the first wavelength range, a first optical signal analyzer adapted to analyze the first optical signals from the interrogation of the measuring equipment, a second optical source adapted to emit optical signals in the second wavelength range, a second optical signal analyzer adapted to analyze the second optical signals in order to determine the optical characteristic of the first functionalized portion of optical fiber, a first connecting element adapted to connect the first optical source and the first optical signal analyzer to the first output of the coupling system, a second connecting element adapted to connect the second optical source and the second optical signal analyzer to the second output of the coupling system.

[0031] With such a configuration, it is possible to separately optimize the optical signals used to query the measurement equipment and those used to query the functionalization of the functionalized portion of optical fiber.

[0032] The optical measurement system may include: a first optical source adapted to emit optical signals in the first wavelength range, a second optical source adapted to emit optical signals in the second wavelength range, an optical signal analyzer adapted to analyze the first optical signals from the interrogation of the measuring equipment and to analyze the second optical signals after interaction with the first functionalized optical fiber portion in order to determine the optical characteristic of the first functionalized optical fiber portion and the corresponding environmental parameter of the connecting optical fiber, a first connecting element adapted to connect the first optical source and the optical signal analyzer to the first output of the coupling system, a second connecting element adapted to connect the second optical source and the optical signal analyzer to the second output of the coupling system.

[0033] In this way, it is possible to provide a simplified and lightweight measurement system, since it only requires a single optical signal analyzer while being able to separately optimize the first and second optical signals, since their emission is obtained by means of separate optical sources.

[0034] The optical measurement system may include: an optical source adapted to emit optical signals in the first wavelength range and in the second wavelength range, a first optical signal analyzer adapted to analyze the first optical signals from the interrogation of the measuring equipment, a second optical signal analyzer adapted to analyze the second optical signals after interaction with the first functionalized optical fiber portion in order to determine the optical characteristic of the first functionalized optical fiber portion and the corresponding environmental parameter of the connecting optical fiber, a first connecting element adapted to connect the optical source and the first optical signal analyzer to the first output of the coupling system, a second connecting element adapted to connect the optical source and the second optical signal analyzer to the second output of the coupling system.

[0035] With such a configuration, it is possible to provide a simplified and lightweight measurement system, since a single light source is used to generate the first and second optical signals.

[0036] The optical measurement system includes: an optical source adapted to emit optical signals in the first wavelength range and in the second wavelength range, an optical signal analyzer adapted to analyze the first optical signals from the interrogation of the measuring equipment and to analyze the second optical signals after interaction with the first functionalized optical fiber portion in order to determine the optical characteristic of the first functionalized optical fiber portion and the corresponding environmental parameter of the connecting optical fiber, a first connection element adapted to connect the optical source and the first optical signal analyzer to the first output of the coupling system, a second connection element adapted to connect the optical source and the second optical signal analyzer to the second output of the coupling system.

[0037] With such a configuration, it is possible to provide a particularly simplified and lightweight measurement system, since only one light source and one optical signal analyzer are used to make the measurements according to the invention.

[0038] The measurement device is a device according to the invention in which the first functionalized optical fiber portion includes a Bragg grating inscribed in the second optical core, the optical measurement system being configurable to measure a variation in the resonant frequency of the Bragg grating from optical signals in the second wavelength range.

[0039] The invention further relates to a measurement method using a measuring device according to the invention, comprising the following steps: emission of first optical signals in the first wavelength range, said first optical signals being transmitted to the first optical output of the coupling system and the first optical core in order to interrogate the measurement equipment, analysis of the first optical signals recovered from the first optical output of the coupling system after interaction with the measurement equipment, emission of second optical signals in the second wavelength range, the second optical signals being transmitted to the second optical output of the coupling system and the second optical core in order to interact with the first functionalized portion of optical fiber,Analysis of the second optical signals recovered from the second optical output of the coupling system after interaction with the first functionalized optical fiber segment, in order to determine the optical characteristic of the first functionalized optical fiber segment and the corresponding environmental parameter of the connecting optical fiber.

[0040] Such a process makes it possible to benefit from the advantages inherent in the use of a measuring device according to the invention.

[0041] The invention further relates to a device comprising a measuring assembly according to the invention.

[0042] Such a turbomachine apparatus benefits from the advantages associated with a measuring set according to the invention.

[0043] The device could be a turbomachine.

[0044] A turbomachine particularly benefits from the possibilities of the invention since the measurement system according to the invention provides access, without the need for a separate sensor, to another parameter of the turbomachine. Thus, it is possible to improve the monitoring of the turbomachine without significantly increasing its size. Brief description of the drawings

[0045] The present invention will be better understood upon reading the description of exemplary embodiments, given purely for illustrative purposes and in no way limiting, with reference to the attached drawings in which: there figure 1 illustrates a measurement set according to a first embodiment of the invention, said measurement set comprising a measurement device according to the invention, the Figures 2A to 2Gillustrate the distribution of optical signals along a connecting optical fiber and internal optical fibers of a measurement system within a measurement assembly as illustrated on the figure 1 this at the level of cross-sectional plans shown on the figure 1 , THE Figures 2A to 2G illustrating the respective optical signals according to a section plane AA and a downstream propagation direction, according to the section plane AA and an upstream propagation direction, according to a section plane BB and the downstream direction, according to the section plane BB and the upstream direction, according to a section plane CC and both upstream and downstream directions, according to a section plane DD and both upstream and downstream directions, and according to a section plane EE and both upstream and downstream directions, the figure 3 illustrates an optical fiber for connecting a measurement assembly according to the first embodiment of the invention, the figures 4A to 4Crespectively illustrate examples of the arrangement of a first and second optical core of the optical fiber according to an FF cutting plane as shown on the figure 3 , there figure 5 illustrates an optical coupling system according to a first possibility of a variant of the first embodiment of the invention in which an optical coupling system of the measurement assembly is external to the connecting optical fiber and for which the separation between first and second optical signals is obtained by means of a dichroic mirror, the figure 6illustrates an optical coupling system according to a second possibility of the variant of the first embodiment of the invention in which the optical coupling system is external to the optical fiber and in which the coupling system is adapted to divide each of the first and second signals into a first and a second sub-beam directed respectively to a first and a second optical output of the coupling system, the figure 7 illustrates a set of measurements according to the variant of the invention of this first embodiment of the invention in which the optical coupling system is, according to the possibility of the invention, illustrated on the figure 5 , THE figure 8 illustrates a measurement set according to a second embodiment in which a measurement system of the measurement set includes a single optical signal analyzer for analyzing the first and second optical signals, the figure 9illustrates a measurement system according to a third embodiment in which the measurement system comprises a single optical source for emitting the first and second optical signals, the Figure 10 illustrates a measurement set according to a variant of the third embodiment in which an optical switch is provided to transmit the first and second optical signals emitted by the optical source to the first and second optical outputs of the coupling system, respectively. figure 11 illustrates a measurement system according to a fourth embodiment in which the measurement system comprises a single optical source for emitting the first and second optical signals and a single optical signal analyzer for analyzing the first and second optical signals, the figure 12illustrates a measurement set according to a variant of the fourth embodiment in which an optical switch is provided to transmit the first and second optical signals emitted by the optical source to respectively the first and second optical output of the coupling system.

[0046] Identical, similar or equivalent parts of the different figures carry the same numerical references in order to facilitate the transition from one figure to another.

[0047] The different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible.

[0048] The different possibilities (variants and modes of implementation) should be understood as not being mutually exclusive and can be combined with each other. Description of the implementation methods

[0049] The invention aims, as shown in the figure 1, a measurement set 1 comprising a measurement system 20 and a measurement equipment 30 connected to each other by a connecting optical fiber 100, the measurement equipment 30 and the connecting optical fiber 100 together forming a measurement device 10.

[0050] More specifically, and according to a preferred application example of the invention, in the present embodiment, the measurement assembly 1 is an acoustic vibration measurement assembly for measuring the acoustic vibrations of a turbomachine, not shown. The measurement assembly 1 thus comprises, as measuring equipment, an optical acoustic vibration sensor similar to the acoustic sensor marketed by Phonoptics™, and the connecting optical fiber 100 includes an inscribed Bragg grating. This example of an embodiment given within the framework of this first embodiment is provided for illustrative purposes only and is in no way limiting.Indeed, a person skilled in the art can extrapolate the teachings of this application to other types of measuring equipment capable of communicating with a measuring system via optical signals and to other types of functionalization of the optical fiber connection 100, as is evident from this description. Similarly, the measuring device according to the invention is not limited to equipping turbomachinery alone and also covers other types of equipment, such as, for example, landing gear or fuselage components of the same turbomachinery.

[0051] It should be noted that such a measuring device 30 is a measuring instrument in its own right and is therefore distinct from a simple section of optical fiber used, for example, to perform a simple reflectometry measurement. Thus, the connection between the measuring device 30 and the connecting optical fiber 100 can be achieved using a suitable connector (not shown). This connector can be either a reversible connector, allowing for easy connection / disconnection of the measuring device 30, or a permanent connector, in which case disconnection would require dismantling and / or damaging the connector.

[0052] Thus, the measurement assembly 1 according to this first embodiment is intended to equip a turbomachine with the measurement equipment 30, the optical connection fiber 100 and the measurement system 20 permanently installed in the turbomachine.

[0053] Alternatively, it is conceivable that only one part of the measurement assembly 1, namely the measurement equipment 30 and the optical connection fiber 100 forming the measurement device 10, is permanently installed in the turbomachine, the measurement system then being connected to the optical connection fiber 100 only in the context of maintenance operations of the turbomachine.

[0054] A connection assembly 1 according to the first embodiment of the invention comprises more specifically: the measuring equipment 30, the connecting optical fiber 100 comprising a first end 131 by which it is connected to the measuring equipment 30, and a second end 135 opposite to the first end 131, a coupling system 140 included in the second end 135 of the connecting optical fiber 100, the optical measuring system 20 configured to poll the measuring equipment by means of first optical signals in a first range of wavelengths λ1, the optical measuring system 20 is connected to the second end 135 of the connecting optical fiber 100 through the coupling system 140 and is thus in communication with the measuring equipment 30 by the connecting optical fiber 100.

[0055] Measuring equipment 30 is a measuring device, such as a sensor, adapted to be interrogated using optical signals. Thus, such measuring equipment 30 could be, for example, an acoustic vibration sensor, a pressure sensor, or a temperature sensor based on an optical measurement of the displacement of a membrane, such as the sensors marketed by Phonoptics ™< . For more information on such sensors, please refer to US document 2017 / 307437.

[0056] With such sensors, the optical measurement system 20 interrogates the measuring equipment 30 by determining the displacement of a membrane based on the reflection rate of the optical signal transmitted by the connecting optical fiber onto said membrane. Since the displacement of this membrane is directly related to the quantity to be measured, it is possible to determine the desired quantity, such as an acoustic vibration, pressure, or temperature.

[0057] Of course, as an alternative to such sensors, the measuring equipment 20 may be something else, such as for example an active temperature sensor, pressure sensor or even an acoustic sensor, the latter being configured to transmit the measurement signal optically to the measuring system 20 via the optical connection fiber 100.

[0058] The measuring equipment 30 is connected to the optical fiber connection 100.

[0059] The 100 Mbps optical fiber connection is as illustrated on the figure 1 , a multi-core optical fiber comprising a first optical core 111 and a second optical core 112 surrounded by an optical cladding 113.

[0060] The first optical core 111 is a multimode optical core in the first wavelength range λ1 capable of transmitting optical signals in the first wavelength range λ1, or in other words, optical signals whose wavelength is within the first wavelength range.

[0061] The second optical core 112 is a single-mode optical core in a second wavelength range λ2 capable of transmitting optical signals in the second wavelength range λ2, or in other words, optical signals whose wavelength is within the second wavelength range λ2.

[0062] It should be noted that, preferably, the first wavelength range λ1 is distinct from the second wavelength range λ2, the first wavelength range λ1 having, in a particularly advantageous way, its minimum wavelength greater than the maximum wavelength of the second wavelength range λ2. It is this latter configuration that is implemented in the present first embodiment.

[0063] However, according to one possibility of the invention, the first wavelength range λ1 and the second wavelength range λ2 may have at least one sub-range of wavelengths in common or even be substantially identical.

[0064] The optical connection fiber 100 includes a first portion of functionalized optical fiber 120 adapted for in the second wavelength range λ2 an optical characteristic varying with an environmental parameter of the optical connection fiber 100.

[0065] According to a preferred embodiment of the invention, in order to allow measurement of the environmental parameter of the optical connection fiber 100, the first functionalized optical fiber portion 120 is included in the first end 131.

[0066] The first functionalized optical fiber portion 120 may, for example, include a Bragg grating 121 inscribed in the second optical core 112, said Bragg grating 121 having a resonant frequency within the second wavelength range λ2. In such a configuration, the optical characteristic exhibited by the first functionalized optical fiber portion 120 in the second wavelength range λ2 and varying with an environmental parameter of the connecting optical fiber 100 is the resonant frequency of the Bragg grating 121.

[0067] Indeed, according to the knowledge of those skilled in the art, the resonant frequency of a Bragg grating inscribed in an optical fiber core varies with environmental parameters of the optical fiber, including temperature and the stresses applied to the fiber. Therefore, by measuring the resonant frequency of the Bragg grating from second optical signals in the second wavelength range λ2, it is possible to identify at least one environmental parameter of the optical fiber, such as temperature.

[0068] In an alternative to the invention not illustrated, the first functionalized optical fiber portion 120 may have a variation in the composition of the second optical core, for example, by doping the core, varying the composition of the cladding, or adding a coating to the first functionalized optical fiber portion 120, such that the first optical fiber portion exhibits an optical characteristic that varies with an environmental parameter of the optical fiber, such as temperature or the presence of a specific substance. Such a variation in characteristic may be, for example, a change in refractive index or a change in fluorescence signal.

[0069] As illustrated on the figure 1, the second end 135 of the connecting optical fiber 100 includes the coupling system 140 on which the first optical core 111 and the second optical core 112 are separated into respectively a first optical fiber segment 136 and a second optical fiber segment 137, this according to the principle of a double-clad coupler, also known by the English name "double-clad coupler" as described in US document 8792757.

[0070] Such a double-clad coupler is made by hot-fusing a dual-core optical fiber with a single-core optical fiber. The optical fiber obtained in such an assembly has a dual-core central portion and, at each of its ends, two output arms corresponding respectively to the single-core and dual-core optical fibers that have been joined together. Furthermore, with such an assembly, the dimensioning of the output arms ensures optical coupling of the first core with only the single-core output arm and optical coupling of the second core with only the dual-core output arm. In the context of the invention, the arms corresponding respectively to the single-core and dual-core optical fibers have been removed at the first end 131 in order to allow connection to the measurement equipment 30.

[0071] Thus, in this way, with such a configuration, the coupling system 140 comprises a first optical fiber segment, corresponding to the single-core optical fiber, optically coupled to the first optical core 111 and optically decoupled from the second optical core 112, and a second optical fiber segment 137, corresponding to the dual-core optical fiber, optically coupled to the second optical core 112 and optically decoupled from the first optical core 112. In this way, the first optical fiber segment 136 allows the recovery of all the first optical signals in the first wavelength range λ1 transmitted by the measuring equipment 30, while the second optical fiber segment 137 allows the recovery of the majority of the second optical signals in the second wavelength range λ2 from the first functionalized optical fiber portion 131.

[0072] Each of the first and second optical fiber segments 136, 137 is connected to the optical measurement system 20 by respectively having the first and second optical output 141, 142 of the coupling system 140.

[0073] The optical measurement system 20 includes: a first measuring unit 210 configured to interrogate the measuring equipment 30 by means of first optical signals in the first wavelength range λ1, said first measuring unit 210 being connected to the first optical fiber segment 136 through the first optical output 141, and a second measuring unit 220 being configured to measure the optical characteristic of the first functionalized optical fiber portion 120 by means of second optical signals in the second wavelength range λ2, said second processing measuring unit 220 being connected to the second optical fiber segment 137, through the second optical output 142.

[0074] As illustrated on the figure 1 The first unit of measurement, 210, includes: a first optical input 231 through which the first measuring unit 210 is connected to the first optical output 141, and thus to the first optical fiber segment 136 of the connecting optical fiber 100, said first optical input 231 being provided with a wavelength-selective optical filter to filter the second optical signals in the second wavelength range λ2 at the input of the second measuring unit 220, a first optical circulator 213 connecting a first optical source 211 to the first optical input 231 and the first optical input 231 to a first optical signal analyzer 212 in such a way that the optical signals from the first optical source 211 are transmitted to the connecting optical fiber 100 and the optical signals from the connecting optical fiber 100 are transmitted to the first optical signal analyzer 212,The first optical source 211 is capable of generating optical signals in the first wavelength range λ1 to interrogate the measuring equipment 30; the first optical signal analyzer 212 is capable of measuring the optical signals in the first wavelength range λ1 transmitted by the measuring equipment 30.

[0075] It should be noted that the first optical circulator 213 forms a first connection element suitable for connecting the first optical source 211 and the first optical signal analyzer 212 to the first optical output 141 of the coupling system 140.

[0076] The optical filter is a wavelength-selective filter and is adapted to attenuate at least partially optical signals in the second wavelength range λ2 and transmit substantially without attenuation the first optical signals in the first wavelength range λ1.

[0077] It should also be noted that the first optical input 231 and the first optical output 141, included in the first optical fiber segment 136, are mechanically connected to each other. Such a mechanical connection can, for example, be achieved by optical splicing, the use of appropriate connectors, or any other type of suitable optical connection in accordance with the general knowledge of a person skilled in the art.

[0078] According to the variant in which only the first measuring element and the optical connection fiber equip the device to be monitored, such as a turbomachine, the connection between the optical connection fiber 100 and the measuring system 20 is only made as part of maintenance operations, the mechanical connection between the first optical input 231 and the first optical output 141 is a reversible connection so as to allow connection and disconnection operations during said maintenance operations.

[0079] The first optical source 211 is an optical source capable of emitting an optical signal in the first wavelength range λ1, either continuously or transiently, such as by emitting pulses of light. Thus, the first optical source 211 is advantageously a laser source, a tunable laser, a light-emitting diode (LED), a laser light-emitting diode, a superluminescent diode, or any light source capable of emitting electromagnetic radiation over a wavelength range and suitable for confinement within an optical fiber. For example, the first optical source 211 may be an optical laser, preferably semiconductor, with at least one emission wavelength corresponding to the first wavelength range.

[0080] The first optical signal analyzer 212 is configured to measure the optical signal in the first wavelength range λ1 transmitted by the measuring equipment 30. Such a first optical signal analyzer 212 can, for example, be provided by a photodiode capable of measuring the intensity of the optical signal transmitted by the measuring equipment 30. Alternatively, the first optical signal analyzer 212 can be capable of measuring another characteristic of the optical signal transmitted by the measuring equipment, such as a pulse frequency, a fluorescence signal or a wavelength spectrum of the first optical signals, via, for example, a detector array, or a resonance wavelength.

[0081] The optical measurement system 20 may further include a processing unit, not shown, capable of controlling the first optical source 211 and the first optical signal analyzer, so as to allow a characteristic value of an environmental parameter measured by the measuring equipment 30 to be determined from the measurement of the optical signal in the first wavelength range λ1 transmitted by the measuring equipment 30.

[0082] As illustrated on the figure 1 The second unit of measurement, 220, includes: a second optical input 232 through which the second measuring unit 220 is connected to the second optical fiber segment 137 of the connecting optical fiber 100, a second optical circulator 223 connecting a second optical source 221 to the second optical input 232 and the second optical input 232 to a second optical signal analyzer 222 so that the optical signals from the second optical source 221 are transmitted to the connecting optical fiber 100 and the optical signals from the connecting optical fiber 100 are transmitted to the second optical signal analyzer 222, the second optical source 221 is capable of generating optical signals in the second wavelength range λ2 in order to perform the measurement of the optical characteristic of the first functionalized optical fiber portion 120, the second optical signal analyzer 222 is capable of measuring the optical signals transmitted by the fiber portion.

[0083] It should be noted that the second optical circulator 223 forms a second connection element suitable for connecting the second optical source 221 and the second optical signal analyzer 222 to the second optical output 142 of the coupling system 140.

[0084] The second optical input 232 and the second optical output 142, included in the second optical fiber segment 137, are mechanically connected to each other. Such a mechanical connection can, for example, be achieved by optical splicing, the use of appropriate connectors, or any other type of suitable optical connection in accordance with the general knowledge of a person skilled in the art.

[0085] According to the variant in which only the first measuring element and the optical connection fiber are fitted to the device to be monitored, such as a turbomachine, the connection between the optical connection fiber 100 and the measuring system 20 is made only as part of maintenance operations, the mechanical connection between the second optical input 232 and the second optical output 142 is a reversible connection so as to allow connection and disconnection operations during said maintenance operations.

[0086] The second optical source 211 is an optical source capable of emitting an optical signal in the second wavelength range λ1, either continuously or transiently, such as by emitting pulses of light. Thus, the first optical source 211 is advantageously a laser source, a tunable laser, a light-emitting diode (LED), a laser light-emitting diode, a superluminescent diode, or any light source capable of emitting electromagnetic radiation over a wavelength range and suitable for confinement within an optical fiber. For example, the first optical source 211 could be an optical laser, preferably semiconductor, with at least one emission wavelength corresponding to the first wavelength range.

[0087] The second optical signal analyzer 212 is configured to measure the optical signal in the second wavelength range λ2 transmitted by the first functionalized optical fiber portion 120. Such a second optical signal analyzer 212 can, for example, be provided by a photodiode capable of measuring the intensity of the optical signal transmitted by the measuring equipment 30. Alternatively, the first optical signal analyzer 212 can be capable of measuring another characteristic of the optical signal transmitted by the measuring equipment, such as a pulse frequency, a fluorescence signal or a wavelength spectrum of the first optical signals, via, for example, a detector array, or a resonance wavelength.

[0088] In the case where the first functionalized optical fiber portion 120 includes a Bragg grating 121, the analyzer may be able to determine a resonant frequency of the Bragg grating 121 or a variation in resonant frequency of this same Bragg grating 121.

[0089] When the optical measurement system 20 includes a processing unit, it can also be capable of controlling the second optical source 221 and the second optical signal analyzer 222, so as to allow the determination, from the measurement of the second optical signals in the second wavelength range λ2 transmitted by the first functionalized optical fiber portion, of a characteristic value of an environmental parameter measured from the optical characteristic of the first functionalized optical fiber portion 120.

[0090] It can be noted that, within the framework of the invention, it is perfectly conceivable that the processing unit comprises a first and a second subunit dedicated respectively to the first measuring unit 210 and the second measuring unit 220. Similarly, such a processing unit can be provided in the form of a dedicated electronic circuit or be integrated, in the form of a program, into a computer, such as a computer embedded in the device to be monitored.

[0091] Such a measurement set 100 allows the parameters of a device to be monitored to be measured from both the measurement equipment 30 and the first functionalized optical fiber portion 120.

[0092] For the remainder of this description, it should be noted that the figure 1The arrow P illustrates a direction of propagation of optical signals called upstream, corresponding to optical signals going from the measuring system 20 to the measuring equipment 30. The opposite direction, corresponding to the direction going from the measuring equipment 30 to the measuring system 20, is called downstream.

[0093] As shown by figures 2A to 2E The operating principle of such measuring equipment is as follows. The first optical source 211 emits first optical signals in the first wavelength range λ1 towards the connecting optical fiber 100, said signal being transmitted via the first optical circulator 213 to the first optical input 231, as shown in cross-section CC along the upstream direction of the figure 2EThe first optical signals in the first wavelength range λ1 are then transmitted from the first optical input 231 to the first optical output 141, and thus to the first optical fiber segment 136, as shown in section BB along the upstream direction of the figure 2C The first optical signals in the first wavelength range λ1 are then confined in the first optical core and coexist with the second optical signals at the second wavelength λ2, emitted by the second measuring unit 220 and confined in the second optical core 112, at the level of the double-clad coupler, as shown by section AA along the upstream direction of the figure 2A The first optical signals in the first wavelength range λ1 are then transmitted to the measuring equipment 30 to allow its interrogation.

[0094] After interaction with the measuring equipment 30, the first optical signals, then called measurement signals, in the first wavelength range λ1 are transmitted by the measuring equipment 30 to the connecting optical fiber 130 as shown by section AA in the downstream direction of the figure 2BThe first optical measurement signals in the first wavelength range λ1 are then transmitted along with the second optical signals in the second wavelength range λ2, also called measurement signals, from the first functionalized optical fiber segment 120. The double-clad coupler separates the first optical measurement signals in the first wavelength range λ1, transmitted only to the first optical fiber segment 136, from the majority of the second optical measurement signals in the second wavelength range λ2. The majority of these second optical signals, remaining confined within the second optical core 112, are directed to the second optical fiber segment 137, as shown in the downstream DD cross-section illustrated in the figure 2FThe first measurement signals in the first wavelength range λ1 are then transmitted from the first optical fiber segment 136 to the first measuring unit 210 via the first output 141 and the optical filter 232. This is done to suppress the minority portion of the second optical measurement signals in the remaining second wavelength range λ2, as shown in the CC section along the downstream direction of the figure 2E . In this way only the first optical measurement signals in the first wavelength range λ1 are transmitted to the first analyzer 212 without the second optical measurement signals in the second wavelength range λ2 disturbing the analysis.

[0095] Similarly, the second optical source 221 emits second optical signals in the second wavelength range λ2 towards the connecting optical fiber 100, said signal being transmitted via the second optical circulator 223 to the second optical input 232, as shown in section EE along the upstream direction of the figure 2G The second optical signals in the second wavelength range λ2 are then transmitted through the second optical input 232 to the second optical fiber segment 137, as shown in section DD along the upstream direction of the figure 2F The second optical signals in the second wavelength range λ2 are then mostly confined within the second optical core and are transmitted in parallel with the first optical signals in the first wavelength range λ1 at the double-clad coupler, as shown by section AA along the upstream direction of the figure 2AThe second optical signals in the second wavelength range λ2 are then transmitted to the first functionalized optical fiber portion 120 to allow its interrogation.

[0096] After interaction with the first portion of optical fiber 120, the second optical signals, then called measurement signals, in the second wavelength range λ2 are transmitted by the first functionalized portion of optical fiber 120 to the rest of the connecting optical fiber 130 as shown by section AA along the downstream direction of the figure 2BThe second optical measurement signals in the second wavelength range λ2 are then transmitted along with the first optical measurement signals in the first wavelength range λ1 from the measurement equipment 30. The double-sheathed coupler then separates the majority of the second optical measurement signals in the second wavelength range λ2 transmitted to the second optical fiber segment 137 from the first optical measurement signals in the first wavelength λ1, which are directed solely to the first optical fiber segment 136, as shown in cross-section DD along the downstream direction of the figure 2F The majority of the second optical measurement signals in the second wavelength range λ2 are then transmitted from the second optical fiber segment 137 to the second measuring unit 220 by means of the second optical input 232, as shown in section EE along the downstream direction of the figure 2G. In this way only the majority of the second optical measurement signals in the second wavelength range λ2 is transmitted to the second analyzer 221 without the first optical measurement signals in the first wavelength λ1 interfering with the analysis.

[0097] It should be noted that in the description of the principle of the invention above, when it is stated that the first and second optical signals, whether measurement or interrogation signals, are transmitted together, it is important to note that this "together" transmission occurs in parallel. Indeed, according to the principle of this first embodiment of the invention, the first optical signals in the first wavelength range λ1 are confined to the first optical core 111, while the majority of the second optical signals in the second wavelength range are confined to the second optical core 112, thus limiting the interaction between these signals.

[0098] Thus, with such a measurement set 1, as described above, it is possible to implement a measurement procedure comprising the following steps: emission of first optical signals, called interrogation signals, in the first wavelength range λ1, said first optical signals being transmitted to the first optical output 141 of the coupling system 140 and the first optical core 111 in order to interrogate the measuring equipment 30, analysis of the first optical signals, called measurement signals, recovered from the first optical output 141 of the coupling system 140 after interaction with the measuring equipment 30, emission of second optical signals, called interrogation signals, in the second wavelength range λ2, the second optical signals being transmitted to the second optical output 142 of the coupling system 140 and the second optical core 112 in order to interact with the first functionalized optical fiber portion 120, analysis of the second optical signals, called measurement signals,retrieved from the second optical output 142 of the coupling system 140 after interaction with the first functionalized optical fiber portion 120 in order to determine the optical characteristic of the first functionalized optical fiber portion 120 and the corresponding environmental parameter of the connecting optical fiber 100.

[0099] Of course, if in the present embodiment, as shown in the Figures 1 to 2G The optical connection fiber is a 100-core multi-core optical connection fiber with concentric cores; other configurations are perfectly conceivable within the scope of the invention, as shown in the diagrams. Figures 3 to 4C .

[0100] Indeed, the figure 3 illustrates a 100-connection optical fiber according to the invention by showing a FF cutting axis and the figures 4A to 4C illustrating three examples of first and second optical core configurations 111, 112 conceivable within the scope of the invention. Thus the figure 4A shows a configuration similar to that of the first embodiment described above in which the first and second optical cores 111, 112 are concentric, the second optical core 112 being housed within the first optical core 111. Alternatively, as shown in the figure 4B The second optical core 112 can be eccentric with respect to a center of the connecting optical fiber 100 and disjoint. According to another embodiment of the invention, the second optical core 112 can be contained within the first optical core 111, itself centered with respect to the center of the connecting optical fiber 100, the second optical core being eccentric with respect to the center of the connecting optical fiber 100.

[0101] As an alternative to this first embodiment and according to one possibility of the invention, the coupling system can be, as illustrated in the Figures 5 And 6 , external to the 100 Mbps fiber optic connection.

[0102] Thus, according to a first possibility of this variant illustrated on the figure 5 , the coupling system 140 can be a coupler based on a separator 146 adapted to separate the first and second optical signals from a distinctive characteristic between the first and second signals.

[0103] In the case where the first wavelength range and the second wavelength range are distinct from each other, the 146 splitter can be based on a dichroic optical component, such as a dichroic mirror or a dichroic filter.

[0104] In cases where the first and second wavelength ranges are at least partially overlapping, the splitter can be based on another distinguishing characteristic of the first and second wavelength ranges, such as polarization or beam size. For example, if polarization is the distinguishing characteristic, such a splitter can be a polarization beam splitter.

[0105] There figure 5illustrates a practical example of a coupling system 140 according to this possibility in which the first wavelength range and the second wavelength range are distinct from each other and in which the separator 146 is a dichroic mirror configured to reflect optical signals in the first wavelength range λ1 and configured to transmit optical signals in the second wavelength range λ2.

[0106] In this practical example, the splitter is placed at 45° to the optical axis of the connecting optical fiber 100, in this way the first optical measurement signals are reflected at 90° to the optical axis of the connecting optical fiber in the upward direction of the figure towards the first optical output 141 and the second optical measurement signals are transmitted without change in its direction of propagation towards the second optical output 142.

[0107] It should be noted that, in the present practical example, the coupling system 140 is preferentially adapted to allow good injection of the first optical signals, emitted by the first optical source 211, into the first optical core 111 and the second optical signals, emitted by the second optical source 221, into the second optical core 112. Such an adaptation can be obtained by a double optimization, that of the distinct configuration, in particular with regard to the beam dimensioning and its focusing state, between the first optical signals and the configuration of the injection optics 145, here a converging lens, used for the injection of the first and second optical signals into the connecting optical fiber.

[0108] It should also be noted that such an adaptation may also come from the configuration of the optical connection fiber 100, of which, according to one possibility of the invention, the second optical core 112 may not be adapted to guide optical signals in the first wavelength range λ1.

[0109] According to a second possibility of this variant, the coupling system 140 can be based on a beam splitter 147 adapted to divide each of the first and second signals into a first and second sub-beam directed respectively to the first and second optical output 141, 142 of the coupling system 140. According to this second possibility, the beam splitter 147 can in particular be provided by a semi-reflective mirror also known by the English name "beam splitter".

[0110] There figure 6illustrates a practical example of a coupling system 140 according to this second possibility in which the beam splitter 147 is a semi-reflective mirror. As shown in the figure 6 , such a coupling system has a sensitive configuration identical to that of the coupling system according to the first possibility with a substitution of the separator 146 by the beam divider 147.

[0111] There figure 7 This illustrates a measuring assembly 1 according to this variant of the invention, in which the coupling system 140 is external to the connecting optical fiber 100, this according to the first possibility in which the coupler comprises a separator 146 for separating the first optical signals from the second optical signals. As illustrated in the figure 7To facilitate the connection of the coupling system with the measurement system 20, the first optical signals are injected, after separation, into a first optical fiber section having a multimode optical core in the first wavelength range. Similarly, the second optical signals are injected, after separation, into a second optical fiber section having a single-mode optical core in the second wavelength range. According to this variant, in addition to the characteristics related to the coupling system 140 itself, the fact that the connecting optical fiber 100 does not include the coupling system 140 at its second end 135, and that the connecting optical fiber 100 is therefore connected to the coupling system 140 via its second end 135, the measurement assembly 1 has a configuration similar to that described in the first embodiment.

[0112] There figure 8illustrates a set of measurements according to a second embodiment according to the variant of the invention illustrated on the figure 7 and in which a single optical signal analyzer 242 is provided in place of the first and second optical signal analyzers 212, 222.

[0113] Thus, a set of measurements according to this second embodiment differs from a set of measurements according to the variant of the first embodiment illustrated in the figure 7 in that it comprises a single optical signal analyzer 242 in place of the first and second optical signal analyzers 212, 222, and in that the measurement assembly further comprises a second coupling system 245 adapted to couple the first and second measurement signals at the level of an input optical fiber of the single optical signal analyzer 242.

[0114] In this second embodiment, the single spectrum analyzer is adapted to analyze the first optical signals from the interrogation of the measuring equipment 30 and to analyze the second optical signals after interaction with the first functionalized optical fiber portion 120 in order to determine the optical characteristic of the first functionalized optical fiber portion 120 and the corresponding environmental parameter of the connecting optical fiber 100.

[0115] In this second embodiment, the first optical circulator 213 connects the first optical source 211 to the first optical input 231 and the first optical input 231 to the second coupling system 245 in such a way that the first optical interrogation signals from the first optical source 211 are transmitted to the connecting optical fiber 100 and the first optical measurement signals from the connecting optical fiber 100 are transmitted to the single optical signal analyzer 242 through the second coupling system 245. Thus, the second coupling system 245 and the first optical circulator 213 together form a first connection element suitable for connecting the first optical source 211 and the single optical signal analyzer 242 to the first output of the coupling system 140.

[0116] Similarly, the second optical circulator 223 connects the second optical source 221 to the second optical input 232 and the second optical input 232 to the second coupling system 245 in such a way that the second optical interrogation signals from the second optical source 221 are transmitted to the connecting optical fiber 100 and the second optical measurement signals from the connecting optical fiber 100 are transmitted to the single optical signal analyzer 242 through the second coupling system 245. Thus, the second coupling system 245 and the second optical circulator 223 together form a second connection element suitable for connecting the second optical source 212 and the single optical signal analyzer 242 to the first output of the coupling system 140.

[0117] Measurement assembly 1 according to the second embodiment has a similar operating principle to that of measurement assembly 1 according to the first embodiment, except that the analysis of the first and second optical signals is performed by the single optical signal analyzer. Thus, as with measurement assembly 1 according to the first embodiment, the interrogation of the measurement equipment 30 and that of the first functionalized optical fiber segment can be carried out in parallel or sequentially.

[0118] There figure 9 illustrates a set of measurements according to a third embodiment according to the variant of the invention illustrated on the figure 7 and in which a single optical source 241 is provided in place of the first and second optical sources 211, 221.

[0119] Thus, a set of measurements according to this third embodiment differs from a set of measurements according to the variant of the first embodiment illustrated in the figure 7 in that it comprises a single optical source 241 in place of the first and second optical sources 212, 222, said single source being adapted to emit in both the first and second wavelength ranges λ1, λ2 and in that the measuring assembly further comprises a beam splitting system 236 for transmitting the optical signals emitted by the single source this as first optical interrogation signals to the first optical input 231, and therefore the first optical output 142, and, as second optical interrogation signals to the second optical input 232.

[0120] In such a third embodiment, according to a first possibility of the invention and with a first and second range of adapted wavelengths, the beam splitting system 236 can be adapted to transmit to the first optical circulator 213 the portion of the emitted radiation corresponding to the first range of wavelengths, this first portion then corresponding to the first optical interrogation signals, and to transmit to the second optical circulator 223 the portion of the emitted radiation corresponding to the second range of wavelengths, this second portion then corresponding to the second optical interrogation signals. Thus, such a possibility can in particular be implemented by means of a dual-core optical fiber with a second single-mode core adapted to guide only the optical signals in the second range of wavelengths.According to this same possibility, it is possible to provide at the level of the separator dichroic filters to separate the first optical interrogation signals from the second optical interrogation signals.

[0121] It can be noted that, in accordance with the possibility described above, if the single optical source 241 is a wavelength-tunable optical source, the emission of the first and second optical signals will have to be sequential, since the optical source cannot, in such a configuration, emit simultaneously in the first and second wavelength ranges if these ranges are disjoint. On the other hand, for an optical source 241 that is a broadband emission source, if it is properly matched, such a configuration allows for the parallel emission of the first and second interrogation optical signals.

[0122] According to another possibility, in which the first and second wavelength ranges are at least partly coincident, the electromagnetic radiation emitted by the single optical source 241 can be separated into two substantially identical optical signals, the first optical signals, transmitted towards the first circulator 213, and the second optical signals transmitted towards the second optical circulator 223. According to this possibility the emission of the first and second signals is necessarily carried out in parallel.

[0123] The measurement assembly 1 according to the third embodiment has a similar operating principle to that of the measurement assembly 1 according to the first embodiment, with the difference that the emission of the first and second optical interrogation signals is carried out by the single optical source 241. Thus, according to the same possibility as that of the measurement assembly 1 according to the first embodiment, the interrogation of the measurement equipment 30 and that of the first functionalized optical fiber portion, depending on the configuration of the single optical source 241 and the beam separation system 236, can be carried out in parallel or sequentially.

[0124] There Figure 10illustrates a measurement set according to a variant of the third embodiment of the invention in which, instead of a beam splitter 246, an optical switch 247 is provided, also known by the English name "optical switch", capable of switching the optical signals emitted by the single optical source 241 between respectively the first optical circulator 213, this to act as first optical interrogation signals, and the second optical circulator 223, this to act as second optical interrogation signals.

[0125] According to such a variant, the electromagnetic radiation emitted by the single optical source is transmitted successively to the first and second optical circulator 213,223.

[0126] Thus, if the measurement assembly 1 according to the third embodiment has a principle of operation similar to that of the measurement assembly 1 according to the third embodiment, the interrogation of the measurement equipment 30 and that of the first functionalized portion of optical fiber can only be carried out sequentially by the successive transmission of the electromagnetic radiation emitted by the single optical source to the first and second optical circulator 213,223..

[0127] There figure 11 illustrates a measurement set according to a fourth embodiment corresponding to a measurement set according to the second embodiment in which, in accordance with the third embodiment, a single optical source 241 is provided in place of the first and second optical sources 211, 221.

[0128] Such a measurement set combines the distinctive characteristics of the measurement sets of the second and third embodiments with respect to the first embodiment. Thus, the operating principle of such a measurement set presents the same considerations as those of a measurement set according to a third embodiment. In this fourth embodiment, the emission of the first and second optical interrogation signals is therefore carried out by the single optical source 241. As with measurement set 1 according to the first embodiment, the interrogation of the measurement equipment 30 and that of the first functionalized optical fiber segment, depending on the configuration of the single optical source 241 and the beam splitting system 236, can be carried out in parallel or sequentially.

[0129] There figure 12illustrates a measurement set according to a variant of the fourth embodiment of the invention in which, instead of a beam splitter 246, an optical switch 247 is provided, also known by the English name "optical switch", capable of switching the optical signals emitted by the single optical source 241 between respectively the first optical circulator 213, this to act as first optical interrogation signals, and the second optical circulator 223, this to act as second optical interrogation signals.

[0130] Such a measurement set combines the distinctive characteristics of the measurement sets of the second embodiment and the variant in the third embodiment with respect to the first embodiment. Thus, the operating principle of such a measurement set presents the same considerations as those of a measurement set according to the variant in the third embodiment. According to this variant in the fourth embodiment, the interrogation of the measurement equipment 30 and that of the first functionalized portion of optical fiber are therefore carried out sequentially by the successive transmission of the electromagnetic radiation emitted by the single optical source to the first and second optical circulators 213, 223.

Claims

1. A measuring device (10) comprising, - a measuring equipment (30) configured to be interrogated optically by a measurement system (20) by means of first optical signals in a first wavelength range (λ1), - a connecting optical fibre (100) comprising a first end (131) connected to the measuring equipment (30) and a second end (135) intended to be connected to the measurement system (20), the connecting optical fibre (100) comprising at least a first multi-mode optical core (111) in the first wavelength range (λ1) for transmitting the first optical signals, the measuring device (10) being characterised in that the connecting optical fibre (100) further comprises a second single-mode optical core (112) in a second wavelength range (λ2) for transmitting second optical signals in the second wavelength range (λ2), in that the connecting optical fibre (100) comprises at least a first functionalised optical fibre portion (120) adapted to have at the second wavelength range (λ2) an optical feature varying with an environmental parameter of the connecting optical fibre (100), and in that the measuring device (10) further comprises a coupling system (140) associated with the second end (135) of the connecting optical fibre (100), the coupling system (140) comprising at least a first and a second optical output (141, 142) and being adapted to optically couple the first optical core (111) with the first output (141) and to optically couple the second optical core (112) with the second output (142).

2. The measuring device (10) according to claim 1, wherein the coupling system (140) is further configured, at the first output (141), to at least partially filter the second optical signals guided through the first optical core (111).

3. The measuring device (10) according to claim 1 or 2, wherein the second end of the connecting optical fibre (100) comprises the coupling system (140), the coupling system (140) comprising a first optical fibre segment (136) optically coupled to the first optical core (111) and optically decoupled from the second optical core (112), and a second optical fibre segment (137) optically coupled to the second optical core (112) and optically decoupled from the first optical core (111), the first optical fibre segment (136) comprising the first optical output (141), the second optical fibre segment (137) comprising the second optical output (142), the coupling system (140) preferably being a double-clad coupler.

4. The measuring device (10) according to claim 1 or 2, wherein the coupling system (140) is external to the connecting optical fibre, such as a splitter capable of splitting the first optical signals and the second optical signals to direct them respectively to the first and the second optical output (141, 142).

5. The measuring device (10) according to any one of claims 1 to 4, wherein the first functionalised optical fibre portion (120) comprises a Bragg grating (121) inscribed in the second optical core (112).

6. The measuring device according to any one of claims 1 to 5, wherein the measuring equipment (30) is a vibration detection system, such as a membrane vibration detection system.

7. A measuring assembly (1) comprising: - a measuring device (10) according to any one of claims 1 to 6, - an optical measurement system (20) configured to interrogate the measuring equipment (30) by means of first optical signals in the first wavelength range (λ1) and to measure the optical feature of the first optical fibre portion (120) functionalised by means of second optical signals in the second wavelength range (λ2), the optical measurement system (20) being connected to the first and to the second optical output (141, 142) of the coupling system (140).

8. The measurement assembly (1) according to claim 7, wherein the optical measurement system (20) comprises: - a first optical source (211) adapted to emit optical signals in the first wavelength range (λ1), - a first optical signal analyser (212) adapted to analyse the first optical signals from the interrogation of the measuring equipment (30), - a second optical source (221) adapted to emit optical signals in the second wavelength range (λ2), - a second optical signal analyser (222) adapted to analyse the second optical signals in order to determine the optical feature of the first functionalised optical fibre portion (120), - a first connection element adapted to connect the first optical source (211) and the first optical signal analyser (212) to the first output of the coupling system, - a second connection element adapted to connect the second optical source (221) and the second optical signal analyser (222) to the second output of the coupling system.

9. The measurement assembly (1) according to claim 7, wherein the optical measurement system (20) comprises: - a first optical source (211) adapted to emit optical signals in the first wavelength range (λ1), - a second optical source (221) adapted to emit optical signals in the second wavelength range (λ2), - an optical signal analyser (242) adapted to analyse the first optical signals resulting from the interrogation of the measuring equipment (30) and to analyse the second optical signals after interaction with the first functionalised optical fibre portion (120) in order to determine the optical feature of the first functionalised optical fibre portion (120) and the corresponding environmental parameter of the connecting optical fibre (100), - a first connection element adapted to connect the first optical source (211) and the optical signal analyser (242) to the first output of the coupling system, - a second connection element adapted to connect the second optical source (221) and the optical signal analyser (242) to the second output of the coupling system.

10. The measurement assembly (1) according to claim 7, wherein the optical measurement system (20) comprises: - an optical source (241) adapted to emit optical signals in the first wavelength range (λ1) and in the second wavelength range (λ2), - a first optical signal analyser (212) adapted to analyse the first optical signals from the interrogation of the measuring equipment (30), - a second optical signal analyser (222) adapted to analyse the second optical signals after interaction with the first functionalised optical fibre portion (120) in order to determine the optical feature of the first functionalised optical fibre portion (120) and the corresponding environmental parameter of the connecting optical fibre, - a first connection element adapted to connect the optical source (241) and the first optical signal analyser (212) to the first output of the coupling system, - a second connection element adapted to connect the optical source (241) and the second optical signal analyser (222) to the second output of the coupling system.

11. The measurement assembly (1) according to claim 7, wherein the optical measurement system (20) comprises: - an optical source (241) adapted to emit optical signals in the first wavelength range (λ1) and in the second wavelength range (λ2), - an optical signal analyser (242) adapted to analyse the first optical signals resulting from the interrogation of the measuring equipment (30) and to analyse the second optical signals after interaction with the first functionalised optical fibre portion (120) in order to determine the optical feature of the first functionalised optical fibre portion (120) and the environmental parameter of the corresponding connecting optical fibre, - a first connection element adapted to connect the optical source (241) and the first optical signal analyser (212) to the first output (141) of the coupling system (140), - a second connection element adapted to connect the optical source (241) and the second optical signal analyser (222) to the second output (142) of the coupling system (140).

12. The measurement assembly (1) according to any one of claims 7 to 11, wherein the measuring device (10) is a measuring device according to claim 5 taken alone or combined with claim 6, and wherein the optical measurement system (20) is configured to measure a change in the resonant frequency of the Bragg grating (121) from optical signals in the second wavelength range (λ2).

13. A measurement method from a measuring device according to any one of claims 1 to 6, comprising the following steps: - emitting first optical signals in the first wavelength range (λ1), said first optical signals being transmitted to the first optical output (141) of the coupling system (140) and the first optical core (111) in order to interrogate the measuring equipment (30), - analysing the first optical signals recovered from the first optical output (141) of the coupling system (140) after interaction with the measuring equipment (30), - emitting second optical signals in the second wavelength range (λ2), the second optical signals being transmitted to the second optical output (142) of the coupling system (140) and the second optical core (112) in order to interact with the first functionalised optical fibre portion (120), - analysing the second optical signals recovered from the second optical output (142) of the coupling system (140) after interaction with the first functionalised optical fibre portion (120) in order to determine the optical feature of the first functionalised optical fibre portion (120) and the environmental parameter of the connecting optical fibre (100).

14. An apparatus comprising a measurement assembly (1) according to any one of claims 7 to 12.

15. The apparatus according to claim 14 wherein said apparatus is a turbomachine.