• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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  • 优先权
    • 专利摘要:
    The invention proposes a method of manufacturing an optical fiber sensor device (1), comprising a housing (10) delimiting a cavity (3) and an optical fiber sensor (2), the optical fiber sensor comprising a optical fiber (12) and a sensor holding device (11) integral with the optical fiber, the holding device being traversed by the optical fiber between two fixing points provided on the holding device. Advantageously, the method comprises the steps of: -positioning the optical fiber sensor (2) in the envelope (10) so as to pass the fiber (12) through two passage openings (130, 140) provided on the envelope (10), the optical fiber extending generally along a longitudinal axis in the cavity (3), which delimits two portions of optical fibers in the envelope, on either side of the holding device (11). ), each fiber portion extending between one of the fixing points of the holding device and one of the passage openings of the casing, substantially along a straight line; - keep the fiber optic sensor in position; performing a differential elongation of the envelope (10) with respect to the optical fiber sensor (2) in the longitudinal direction, and towards the outside of the envelope (10), whereas the optical fiber sensor remains maintained in position; attaching the optical fiber to the envelope (10) at said passage openings; and - returning the envelope (10) to an equilibrium position.
    公开号:FR3034207A1
    申请号:FR1500613
    申请日:2015-03-27
    公开日:2016-09-30
    发明作者:Francois Xavier Launay；Raphael Lardat；Gerard Roux
    申请人:Thales SA；
    IPC主号:
    专利说明:

    [0001] FIELD OF THE INVENTION The invention generally relates to measurement systems, and in particular optical fiber sensor devices and methods of manufacturing such devices. PRIOR ART An optical fiber sensor comprises an optical measuring fiber whose optical characteristics are sensitive to a physical quantity. When light is injected into the optical fiber, a light signal is generated and detected by the sensor. This signal is then converted and processed to return the measured quantity. Fiber optic sensors are widely used in various types of applications not only because of their small footprint (relatively small size and weight) and their insensitivity to electromagnetic interference, but also because they are particularly suited to multiplexing and implementation of amplifiers or distributed sensors. They also limit the intrusiveness of the sensor in the environment. Some fiber optic sensors use Bragg gratings embedded in the fiber. A Bragg grating is a reflector comprising alternating layers of different refractive indices, which causes a periodic variation of the effective refractive index in the optical fiber. Bragg grating fiber sensors are used to measure a physical quantity that corresponds to a stress applied to the sensor. The stress applied to the sensor induces a variation of wavelength. Bragg grating optical fiber sensors can be passive or active (optical fiber laser sensor). The optical fiber sensors Bragg gratings are arranged in a protective envelope, crossed on both sides by the optical fiber. When mounting such a sensor, it is useful to leave an extra length of fiber untensioned within the enclosure. Indeed, in the absence of such additional length, the optical fiber stretched may generate stiffness in a wide range of operation (including temperature range) which is detrimental to the proper operation of the sensor. Moreover, such an additional ionizer allows the fiber to filter the mechanical disturbances that can come from outside the sensor. A known solution for producing an additional length of fiber is illustrated in FIG. 1. According to this approach, at least one loop 23 is made with the fiber 22 in the envelope 20 which houses the sensor 21, which makes it possible to release a extra length. However, such a solution generates a large footprint because of the minimum radius of curvature allowed for an optical fiber (of the order of one cm). This solution is therefore not suitable for compact sensors.
    [0002] General definition of the invention The invention improves the situation. For this purpose, it proposes a method for manufacturing an optical fiber sensor device comprising a casing defining a cavity and an optical fiber sensor, the optical fiber sensor comprising an optical fiber and a device for holding the integral sensor. of the optical fiber, the holding device being traversed by the optical fiber between two fixing points provided on the holding device. Advantageously, the method comprises the steps of: positioning the optical fiber sensor in the envelope so as to pass the fiber through two passage openings provided on the envelope, the optical fiber generally extending in a manner longitudinal axis in the cavity, which delimits two portions of optical fibers in the envelope, on either side of the holding device, each fiber portion extending between one of the attachment points of the holding device and a passage openings of the envelope, substantially along a straight line; -Maintain the fiber optic sensor in position; 3034207 3 - Perform a differential elongation of the envelope relative to the optical fiber sensor in the longitudinal direction, and to the outside of the envelope, while the optical fiber sensor remains in position; attaching the optical fiber to the envelope at said passage openings; and 5 - return the envelope to a position of equilibrium. According to one characteristic, the step of differential elongation of the fiber is carried out by mechanically stretching the envelope in the longitudinal direction, on each side of the envelope, towards the outside of the envelope, while the envelope is brought back to the equilibrium position by releasing the envelope.
    [0003] In one embodiment, the differential elongation AL of the envelope with respect to the optical fiber sensor satisfies a stress relating to the surrounding temperature Ts at the time of fixing the fiber to the envelope, at the maximum temperature T max of the fiber sensor, the coefficient of thermal expansion Δc of the fiber sensor and the thermal expansion coefficient λp of the envelope. In particular, the constraint is defined by the inequality: AL if - 11 /) (Tmax TS) - 2-C (Tmax TS) where Ùc represents the coefficient of thermal expansion of the device for holding the fiber sensor, at the coefficient The thermal expansion of the envelope, Lc denotes the length of the fiber sensor, Lp is the length of the envelope, Ts is the surrounding temperature at the time of attachment of the fiber to the envelope, and Tmax is the maximum temperature of the envelope. sensor operation. In another embodiment, the differential elongation step is performed by differential thermal expansion of the shell with respect to the optical fiber sensor by increasing the temperature to a temperature of expansion greater than the maximum operating temperature. defined for the fiber optic sensor device, while the envelope is returned to the equilibrium position by bringing the temperature to a temperature below the expansion temperature.
    [0004] The envelope may then be chosen so as to have a coefficient of thermal expansion according to the equation: LpAp> LcAc, where Ac denotes the coefficient of thermal expansion of the sensor holding device, A denotes the coefficient of thermal expansion of the envelope, 1-c denotes the length of the holding device, and Lp denotes the length of the envelope. In particular, the differential elongation ./.1'L of the envelope can be equal to: = -L) 1 'AP (7. - T1) - 1' - ilc (T - Ti) 2 where Ac denotes the coefficient of thermal expansion of the sensor, at the coefficient of thermal expansion of the envelope, Lc denotes the length of the holding device, Lp denotes the length of the envelope, T the operating temperature, and T1 the expansion temperature. According to a complementary feature, the step of attaching the fiber to the envelope at the passage apertures may include bonding the fiber at the blocking points. The manufacturing method may further include attaching the fiber sensor to the envelope at at least one splice area. The attachment of the sensor to the envelope at at least one connection zone may in particular be carried out by gluing.
    [0005] According to another characteristic, the positioning step of the optical fiber sensor may comprise the longitudinal positioning of the optical fiber sensor substantially in the middle of the envelope. In one embodiment, the sensor may be a hydrophone. The invention further provides an optical fiber sensor device comprising an envelope defining a cavity, an optical fiber sensor, the fiber optic sensor comprising an optical fiber and a holding device integral with the optical fiber, the holding device being traversed by the optical fiber between two fixing points provided on the holding device. Advantageously, the optical fiber passes through the envelope at two passage openings provided on the envelope and extends generally along a longitudinal axis in the cavity, which delimits two portions of optical fibers of given lengths in the envelope. , on either side of the holding device, each portion of fiber extending between one of said fixing points of the holding device and the passage opening of the casing situated on the same side of the optical fiber sensor and being substantially in a straight line, each fiber portion comprising a distension so that the length of each fiber portion extending between a fastening point of the holding device and an opening of the envelope is greater than the distance geometric connection between the attachment point of the holding device and the passage opening. In particular, the wavelength of the light that passes through the optical fiber of the sensor device is a linear function of a stretching parameter corresponding to a stretching applied to the sensor device, the linear function exhibiting a failure of the sensor device. slope for a critical value of the stretching parameter such that the directing coefficient of the linear function after the critical value is greater than the directing coefficient of the linear function before the critical value.
    [0006] The invention thus makes it possible to carry out differential stretching of the container with respect to the sensor before connecting the container to the optical fiber and / or the sensor. DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent with the aid of the description which follows and the figures of the accompanying drawings, in which: FIG. 1 is a diagram showing a fiber optic sensor device according to a approach of the prior art; Figure 2 is a diagram showing an optical fiber sensor device according to some embodiments of the invention; FIG. 3 is a diagram illustrating the differential elongation of the envelope with respect to the optical fiber sensor according to certain embodiments of the invention; FIG. 4 is a flowchart showing the method of manufacturing an optical fiber sensor device according to one embodiment of the invention; FIG. 5 is a flowchart showing the method of manufacturing an optical fiber sensor device according to another embodiment of the invention; and FIG. 6 is a diagram showing the evolution of the wavelength as a function of a stretching parameter corresponding to a stretch applied to the sensor device. The drawings and appendices to the description may not only serve to better understand the description, but also contribute to the definition of the invention, if any.
    [0007] DETAILED DESCRIPTION Fig. 2 shows an optical fiber sensor device 1 according to some embodiments of the invention. The optical fiber sensor device 1 comprises an envelope 10 delimiting a cavity 3 and at least one optical fiber sensor 2 housed in the cavity 3.
    [0008] The invention will be described below in connection with a single optical fiber sensor 2 housed in the cavity 3 by way of non-limiting example. The optical fiber sensor 2 comprises an optical fiber 12 whose optical characteristics are sensitive to a physical quantity, and a holding device 11 integral with the optical fiber 12. The holding device 11 is traversed by the optical fiber and is fixed to it at two fixing points 110 and 111 provided on said holding device. The holding device 11 is configured to hold the fiber in position in the cavity 3. It may further comprise additional elements for mechanical amplification in certain acoustic applications for example.
    [0009] The optical fiber sensor 2 may be any type of sensor configured to measure a physical quantity, such as for example an optical fiber hydrophone, a sensor for deformation, pressure, temperature, acceleration, etc. Although not limited to such applications, such a fiber sensor 2 is particularly suited to acoustic hydrophone applications for detecting acoustic pressure variations. Indeed, the electronic components do not have to be provided in the submerged part. As a result, they can be towed easily and it is possible to multiplex on the same fiber several optical fiber sensor devices 1.
    [0010] The envelope 10 may be configured to mechanically protect the sensor, in particular against impacts, against certain forces due to the environment (for example water), against corrosion, etc. The envelope 10 may for example be in the form of a rigid body such as a cylindrical tube whose generating line coincides substantially with the general axis of the optical fiber 12.
    [0011] The envelope may be formed of several elements assembled together or have a one-piece structure. The cavity 3 delimited by the envelope 10 may be filled with a protective fluid such as oil to optimize the operation and the life of the sensor. The envelope can be flexible or rigid and sealed to isolate the fluid that it contains from the outside environment. According to one aspect of the invention, the optical fiber 12 passes through the envelope 10 in a sealed manner at two passage openings 130 and 140 provided on the envelope. These passage apertures can be arranged respectively on two sides of the envelope, as for example the two opposite faces 13 and 14. In the cavity 3, the optical fiber extends generally along a longitudinal axis, which delimits two portions of optical fibers 120 and 121 of given lengths, in the envelope, on either side of the holding device 11. Each fiber portion 120 and 121 extends between one of the passage openings of the envelope 130 and 140 and the point of attachment of the holding device 30 (respectively 110 and 111) closest. Thus, the fiber portion 120 extends between the entry point E10 of the envelope 10 and the entry point E11 of the holding device 30, into the cavity 3 while the fiber portion 121 extends between the exit point S10 of the envelope 10 and the exit point S11 of the holding device 11, in the cavity 3. The optical fiber element 12, forming the active part of the sensor 2 thus enters the cavity 3 by the point E10 and out of the cavity by point S10, through the openings of passages 130 and 140. In addition, the optical fiber 12 may comprise at least one Bragg grating 15 inscribed on the fiber and configured to emit wavelengths sensitive to the mechanical stress applied to the optical fiber 12. The measurement of these wavelength variations makes it possible to deduce the stress applied to the optical fiber 12 and consequently to measure a physical quantity such as the pressure acoustic for example, in use is an interrogation box. In known manner, the optical fiber 12 may consist of a tube (for example silica tube) of a hundred microns in diameter and comprise at its center a core forming a conduit for channeling the light. The fiber can be illuminated by means of a laser beam with a periodic array of interference fringes. The Bragg grating or networks may be photo-inscribed one after the other on the fiber 12. In addition, the fiber 12 may comprise a protective sheath to mechanically protect the fiber.
    [0012] The Bragg grating 15 may comprise a set of successive rings inscribed transversely in the core of the fiber (for example by photo-inscription), the distance between each ring representing the pitch of the grating which is representative of a length of given wave. When light is injected into the fiber 12, it can propagate in the longitudinal direction (direction of the fiber) until it reaches the Bragg grating 15. The Bragg grating then filters the length of the fiber. wave corresponding to his step by opposing the passage of the line of this wavelength and reflecting it. The spectrum of the reflected beam can then be analyzed. Deformation of the fiber causes a change in the pitch of the grating, and consequently a variation of the wavelength of the beam reflected around its initial value, this variation being proportional to the stretching of the fiber. The analysis of the variation of the wavelength thus makes it possible to measure the physical quantity which induced the deformation of the fiber (for example the acoustic pressure). It will be understood by those skilled in the art that the invention is not limited to an optical fiber 12 comprising an inscribed Bragg grating and can be applied to other types of optical fibers, such as for example a coil fiber or a fiber of type CLFO (Laser Fiber Optic Sensor) equipped with a Bragg grating. In one embodiment, the envelope 10 may comprise two faces 13/14 vis-à-vis each comprising a passage opening respectively 130/140 to allow the passage of the optical fiber 12.
    [0013] After assembly of the sensor device 1, the envelope 10 is secured to the optical fiber 12 at the two passage openings 130 and 140 of the envelope 10 and each portion 120 and 121 of the fiber 12 extends substantially according to a axis (ie substantially in a straight line). The optical fiber 12 can be fixed to the casing 10 at the passage openings 130 and 140 by any rigid connection means 15 such as for example by welding (eg laser welding) or bonding (eg bonding by polyamide coating or by epoxy glue ). In the embodiment of FIG. 3, the fixing at the points of passage 130 and 140 between the fiber 12 and the envelope is carried out using bonding points 170. In addition, the holding device 11 of the sensor 2 It can be attached to the envelope 10 at connection points 171. According to one aspect of the invention, the portions of the optical fiber 120 and 121 located inside the cavity 3 on either side of the holding device 11 comprises a distension carried out by differential elongation of the envelope 10 (also called "differential stretching" hereinafter) with respect to the optical fiber before fixing the fiber to the envelope 10 at the openings of passage 130 and 140 of the envelope 10. As used herein, the term fiber "distension" refers to the fact that the length of each fiber portion 120 and 121 within the cavity 3 is greater than the distance geometric ([EwEi 1] and [Si iSio]) between the entry point Eu) (or respectively the exit point Sio) of the optical fiber 12 in the cavity 3 delimited by the envelope 10 and the entry point E11 (or respectively the output point S11) of the optical fiber 12 in the holding device 11 ([E10E11] <L1 and [Si iSioj <L2). FIG. 3 illustrates the differential elongation of the envelope 10 with respect to the optical fiber sensor 2. The differential elongation of the envelope 10 with respect to the sensor is carried out after the integration of the fiber sensor 2 with the inside the casing 10, while the fiber sensor 2 (assembled) is held in position by any suitable tools (the fiber sensor 2 remains fixed and can not move). The envelope 10 passes from a first position (shown diagrammatically in dashed lines in FIG. 3), following a differential elongation of the envelope with respect to the optical fiber sensor, at a position of equilibrium after having fixed the fiber 12 at the passage openings 130 and 140 (shown in solid lines in Figure 3). The envelope 10 thus undergoes a variation in length between two instants, on each side of the fiber sensor 2, representing its differential stretching. Thus the differential stretching ALisubi through the casing 10 on the side of the passage opening 130 is given by the relation: AL, = L1 '- L1, L1' represents the length between the point of entry E'10 of the envelope 10 and the entry point E11 of the holding device 11, in the cavity 3, in the first differential elongation position of the envelope 10.
    [0014] L1 represents the length between the entry point E10 of the envelope 10 and the entry point E11 of the holding device 11, in the cavity 3, in the equilibrium position of the envelope 10. Similarly, differential stretch Aksubi through the casing 10 on the side of the passage opening 140 is given by the relation: AL2 = L2 '- L2 25 L2' represents the length between the exit point S'Io of the casing 10 and the exit point Sui of the holding device 11, in the cavity 3 in the first differential elongation position of the envelope 10.
    [0015] L2 represents the length between the exit point S10 of the envelope 10 and the exit point S11 of the holding device 11, in the cavity 3 in the equilibrium position of the envelope 10. The introduction of such a differential elongation during the manufacturing phase 5 thus makes it possible to obtain a sensor device 1 having a distension on each portion of fiber 120 and 121, after manufacture. The distension of each fiber portion 120 and 121 of the sensor device 1 thus depends on the stretch. In particular, the distension D1 of the fiber portion 120 satisfies the relationship: D1 L1 + AL1 10 The distension D2 of the fiber portion 121 satisfies the relationship: D2 "^: L2 + A L2 In a preferred embodiment, L1 is equal to L2 (L1 = L2 = L) and L1 'is equal to L2' (L1 '= L2' = L). The two portions of fibers 120 and 121 thus have substantially the same length The following description will be made with reference to this embodiment, by way of non-limiting example.The differential stretching of the envelope, of each the sensor side will thus be noted: AL = - L The distensions obtained on each fiber portion 120 and 121 are then noted: D = D2 = L + AL In a first embodiment, the differential elongation of the envelope 10 by compared to the optical fiber can be achieved by mechanical stretching. n, the stretching of the envelope 10 can be achieved by mechanically maintaining it in extension before the fixing of the fiber 12 to the envelope 10 (at the passage openings 130 and 140), for example by gluing to level of attachment points (130, 140). Such mechanical stretching may be effected by using a stretching device which hooks on and off the casing 10 and extends it longitudinally outwardly of the sensor device 1 as indicated by arrows 41 and 42, while the optical fiber sensor 2 is held in position within the cavity 3, or by prior fixing of the holding device 11 to the casing 10 at the connection points 171 (by example by gluing), or by using a tool adapted to maintain in position the holding device (integral with the fiber) during stretching. In FIG. 3, the length Lc denotes the length of the holding device 11 and the length Lp denotes the length of the envelope 10.
    [0016] In this first embodiment, an over-length is thus obtained at each fiber portion 120 and 121 by mechanical stretching of the envelope 10, while the sensor 2 remains held in position. Considering that Ts designates the surrounding temperature in the phase of fixing the fiber and / or the sensor 2 to the envelope and that Tmax denotes the maximum operating temperature of the sensor 2, the stretching AL of the envelope 10 is realized in order to satisfy the following equation (mechanical stretching stress): AL k .4 (Tmax - Ts) - * 2 - c (Tmax - Ts) (Equation 1) In the equation above, Ac designates the coefficient of thermal expansion of the holding device 11 of the sensor 2 and Àp designates the thermal expansion coefficient of the envelope 10. Lc, LP, AiL may especially be expressed in meters, Ts and Tmax in degrees Celsius (° C) and Àc and Ap in reciprocal degree Celsius (° C-1). The envelope 10 can then be released (by releasing it from the stretching device) after attachment of the fiber 12 to the envelope 10 at the passage openings to return to an equilibrium position, thereby generating a distension D on each portion 120 and 121. The mechanical stretching AL achieved by stretching the casing 10, according to the equation 1, before fixing the fiber to the casing 10, at the passage openings 130 and 140 , allows to maintain a fiber distension on each portion 120 and 121, even if the maximum operating temperature is reached.
    [0017] In a second embodiment, the differential stretching of the envelope 10 with respect to the optical fiber can be carried out by thermal expansion, before the fixing of the fiber 12 to the envelope 10 at the passage openings. The thermal expansion is carried out so that the envelope 10 undergoes an expansion greater than that of the sensor 2, under the effect of the applied temperature. In particular, the envelope 10 may be chosen so as to have a coefficient of thermal expansion according to equation 2 below, which makes it possible to obtain an expansion of the envelope 10 greater than that of the sensor 2. LPAp> Lcitc (Equation 2) During the thermal expansion, the sensor 2 is held in position inside the cavity 3 either by prior fixing of the holding device 11 to the casing 10 at the connection points 171, or using a tool adapted to maintain in position the holding device 11 (integral with the fiber) during the expansion.
    [0018] In this embodiment, the attachment of the fiber 12 to the casing 10 at the passage openings 130 and 140 and / or the attachment of the optical fiber sensor 2 to the casing 10 at the connection points 171 can advantageously be carried out at a temperature greater than the maximum temperature of use of the sensor device 1.
    [0019] Throughout the temperature operating range, the fiber portions 120 and 121 are thus loose due to the differential shrinkage of the envelope 10 relative to the sensor 2. Considering that the attachment of the fiber 12 to the envelope 10 (for example by gluing) at the passage openings takes place at a temperature T1, a variation L of the fiber can be obtained by thermal expansion, for an operating temperature T <T1, according to the equation following: 0fL = if - - T1) - - ÀC (T - T1) (Equation 3) Lc, Lins A'L can in particular be expressed in meters, T and T1 can be expressed in degrees Celsius (° C) and Ac and In degrees Celsius reciprocal (° C-1).
    [0020] In order to obtain loose fiber portions 120 and 121 inside the cavity 3 delimited by the envelope 10, the variation of length 3, L defined in equation 3 satisfies 3, L <0 whatever the temperature T in the operating range of the sensor, which amounts to choosing the materials of the sensor 2 and the envelope 10 so as to satisfy the equation 2. FIG. 4 illustrates the method of manufacturing the sensor device optical fiber 1, according to the first embodiment or the differential stretching is performed mechanically prior to the attachment of the fiber and the casing to the passage openings 130 and 140. In step 400, the fiber sensor 2 is assembled and integrated in the casing 10 so that the fiber 12 passes through the passage openings 130 and 140 without being fixed thereto and each fiber portion 120 and 121 extends substantially in a straight line. . In this phase, the fiber sensor 2 can be positioned substantially in the middle of the cavity 3. In step 401, the optical fiber sensor 2 is held in position. In one embodiment, it can be held in position by fixing the holding device 11 of the sensor 2 to the envelope at the connection points 171, for example by gluing. Alternatively, the optical fiber sensor 2 can be held in position using a suitable tooling.
    [0021] In step 402, a differential stretching of the casing 10 with respect to the sensor 2 is performed mechanically along the longitudinal axis 16 at each end face 13 and 14 of the casing 10 on which the casing 10 is arranged. one of the passage openings 130 and 140, towards the outside of the envelope 10 (according to the arrows 41 and 42 shown in FIG. 3), for example using a stretching device 30 which hangs on and other of the envelope 10 at each end face 13 and 14.
    [0022] In step 403, the fiber 12 is attached to the envelope at each passage opening 130 and 140, for example by gluing. Assuming that the fixation of the fiber 12 to the envelope 10 is performed at a temperature Ts, the mechanical stretching of the envelope is such that the envelope undergoes an elongation AL, according to equation 1. In the modes embodiment, where the sensor 2 is held in position at the step 401, without fixing the sensor 2 to the envelope at the connection points 171, the method may comprise the step 404 for fixing the holding device 11 of the sensor 2 to the casing 10 at the connection points 171. As a variant, this step of fixing the holding device 11 of the sensor 2 to the casing 10 can be performed before or during the step 403. step 405, the envelope 10, to which are fixed the fiber portions 120 and 121 at the passage openings and the sensor holding device 2, is released so that the envelope returns to position. This results in a distension on each fiber portion 120 and 121. The optical fiber sensor device 1 thus obtained can then be used in any operating environment where the temperature is less than Tmax. Figure 5 illustrates the manufacturing method according to the second embodiment wherein the stretching of the fiber is performed by thermal expansion. In step 500, the optical fiber sensor 2 is assembled and integrated in the envelope 10 so that the fiber 12 passes through the passage openings 130 and 140, without being fixed thereto, and that each portion of fiber 120 and 121 extends substantially in a straight line, as described in connection with step 400 of FIG. 4. In step 501, the optical fiber sensor 2 is held in position as described in connection with step 401 of FIG. 4 (by means of a tool for holding or fixing the device for holding the sensor 11 to the envelope 10).
    [0023] In step 502, the pre-assembled elements of the fiber sensor device 1 are exposed to a temperature T greater than the maximum operating temperature Tmax of the sensor device 1, using a heating system. The heating system is started between a start temperature To and the temperature is increased until the temperature stabilizes at the temperature T1. By increasing the operating temperature gradually to the temperature T1 while keeping the fiber optic sensor 2 in position, the envelope 10 expands more than the sensor 2, which generates a differential elongation of the envelope 10 by 2. In step 503, the fiber 12 is attached to the envelope at each passage opening 130 and 140, for example by gluing. Assuming that the attachment of the fiber 12 to the casing 10 is effected at the temperature T1, the thermal expansion method makes it possible to obtain a differential elongation of the casing with respect to the sensor, according to the equation 3 It thus appears a distension at each fiber portion 120 and 121 which depends on this differential elongation. In the embodiments, where the sensor 2 is held in position at step 501, without attaching the sensor 2 to the envelope at the connection points 171, the method may comprise a step 504 for fixing the device holding 11 of the sensor 2 to the casing 10 at the connection points 171. In a variant, this step of fixing the holding device 11 of the sensor 2 to the casing 10 may be performed at any time before, during or after the In step 505, the envelope is brought back to a temperature lower than T1 (for example, surrounding temperature), which enables it to be brought back to a position of equilibrium. The optical fiber sensor device 1 thus obtained can then be used in any operating environment where the temperature is lower than T1.
    [0024] The various embodiments proposed thus make it possible to obtain a distension of the optical fiber portions 120 and 121 on either side of the sensor 2, before fixing the fiber to the envelope at the passage openings. The over-fiber length thus obtained makes it possible to limit the risk of stiffness of the tensioned fiber whatever the operating range (in particular whatever the temperature range) while filtering the mechanical disturbances that can come from outside. of the sensor by the fiber 12. The optical fiber sensor device 1 thus obtained is characterized by a particular law of wavelength variation with respect to a stretching applied to the device, as illustrated in FIG. 6, whatever the stretching method applied (by thermal expansion, by mechanical stretching) and independently of the stretching method applied during the manufacture of the sensor device 1. More specifically, the wavelength of the light which passes through the optical fiber of the device 1 is a linear function of a stretch parameter corresponding to a stretch applied to the sensor device, the linear function 15 breaking slope for a critical value of the stretching parameter. Thus, if a progressive stretch is applied to the sensor device 1 (after fabrication), represented by a stretching parameter S, it has been observed that the wavelength λ advances as a function of the stretching S up to a critical value SO along a first increasing straight line 50 and, after the critical value SO along a second increasing straight line 51, the steering coefficient of the second straight line being greater than the directing coefficient of the first straight line 50. The slope failure (passage of the first line 50 to the second straight line 51) thus occurs at the point S0 which can correspond substantially to the bonding temperature of the fiber to the envelope 10 or to the maximum stretching of the envelope 10 according to the embodiment of FIG. manufacturing process. Once the breaking point reached, the fiber 12, inside the cavity 3, tends. Such characteristic behavior of the fiber sensor device 1 can be observed for example by placing the sensor device 1 (after manufacture) in an oven where the temperature is gradually increased to achieve stretching of the device by thermal expansion (in this case the stretching parameter S can be the temperature) or mechanically stretching the sensor device 1.
    [0025] The different embodiments of the invention therefore make it possible to obtain a good operation of the optical fiber sensor device 1 over a wide range of use, in particular in temperature, by introducing such an over-length of fiber. between the sensor 2 and its envelope 10, during the manufacturing process of the device 1. Such a solution has no impact on the volume of the cavity 3 delimited by the envelope 10. Moreover, the different modes of embodiment of the invention limit the risk of breakage of the optical fiber. Indeed, the fiber displacements being very weak, the elongation of the fiber during the manufacturing process does not generate buckling of the optical fiber 10 which may cause a break in the fiber 12. By carrying out the elongation directly during the manufacturing process, a relatively compact fiber sensor 1 can be obtained without weakening the optical fiber, which is particularly useful in certain applications such as acoustic applications where the fiber optic sensor 1 is used as an hydrophone.
    [0026] The invention is not limited to the embodiments described above by way of non-limiting example. It encompasses all the embodiments that may be envisaged by those skilled in the art. In particular, the invention is not limited to a particular number of connection areas between the sensor 2 and the envelope 10. In addition, it is not limited to a particular sensor application or to a particular form. envelope. In particular embodiments, the envelope 10 may consist of different materials and different elements assembled together to form an envelope.
    [0027] Furthermore, although the invention has been described in connection with an embodiment where the envelope 10 comprises a single fiber sensor 2, it can also be applied to a plurality of sensors connected in parallel (the set sensors that can be maintained for example by a common holding device 11) or connected in series. 30
    权利要求:
    Claims (14)
    [0001]
    REVENDICATIONS1. A method of manufacturing an optical fiber sensor device (1), comprising an envelope (10) defining a cavity (3) and an optical fiber sensor (2), said optical fiber sensor comprising an optical fiber (12) and a device for holding the sensor (11) integral with the optical fiber, said holding device being traversed by the optical fiber between two fixing points provided on said holding device, characterized in that it comprises the steps of: positioning the optical fiber sensor (2) in the envelope (10) so as to pass the fiber (12) through two passage openings (130, 140) provided on the envelope (10), the optical fiber extending generally along a longitudinal axis in said cavity (3), which delimits two portions of optical fibers in the envelope, on either side of the holding device (11), each portion of fiber s' extending between one of said fixing points of the holding itif and one of said openings for passage of the envelope, substantially in a straight line; - keep the fiber optic sensor in position; performing a differential elongation of the envelope (10) with respect to the optical fiber sensor (2) in the longitudinal direction, and towards the outside of the envelope (10), whereas the optical fiber sensor remains maintained in position; attaching the optical fiber to the envelope (10) at said passage apertures; and - returning the envelope (10) to an equilibrium position.
    [0002]
    2. Manufacturing process according to claim 1, characterized in that said step of differential elongation of the fiber is performed by mechanically stretching the envelope (10) in said longitudinal direction, on each side of the envelope (10). , towards the outside of the envelope, and in that the envelope is returned to said equilibrium position by releasing the envelope.
    [0003]
    3. Manufacturing method according to claim 2, characterized in that the differential elongation AL of the envelope (10) with respect to the optical fiber sensor (2) satisfies a stress relative to the surrounding temperature Ts at the moment of 3034207. fixing the fiber to the casing (10), the maximum operating temperature Tmax of the fiber sensor (2), the thermal expansion coefficient Ac of the fiber sensor (2) and the thermal expansion coefficient itp of the envelope (10). 5
    [0004]
    4. Manufacturing process according to claim 3, characterized in that said stress is defined by the inequality: OL> If - 21) (Tmax Ts) 1L2c '- 11C (Tmax 7.5) 1 Where Ac denotes the coefficient of thermal expansion of the fiber sensor (2), Δp the coefficient of thermal expansion of the envelope, Lc denotes the length of the fiber sensor (2), Lp denotes the length of the envelope (10), Ts the ambient temperature at the time from fixing the fiber to the envelope (10), and Tmax the maximum operating temperature of the sensor.
    [0005]
    5. Manufacturing method according to claim 1, characterized in that said differential elongation step is performed by differential thermal expansion of the envelope (10) relative to the optical fiber sensor (2) by increasing the temperature until at a temperature of expansion greater than the maximum operating temperature defined for the optical fiber sensor device (1), and in that the envelope is returned to said equilibrium position by lowering the temperature to a temperature below the expansion temperature.
    [0006]
    6. Manufacturing process according to claim 5, characterized in that the casing 10 is chosen so as to have a coefficient of thermal expansion according to the equation: LpAp> LcAc, where Ac denotes the coefficient of thermal expansion of the device. holding the sensor (2), itp the coefficient of thermal expansion of the envelope, Lc denotes the length of the holding device (11), and Lp denotes the length of the envelope (10). 3034207 21
    [0007]
    7. The manufacturing method according to claim 6, characterized in that the differential elongation of the envelope (10) is equal to: Lp Lc A'L = -2. 2.1D (T - T1) -2. iic (T-Ti) where λc denotes the coefficient of thermal expansion of the sensor (11), At the coefficient of thermal expansion of the envelope, Lc denotes the length of the holding device (11), Lp denotes the length of the envelope (10), T the operating temperature, and T1 the expansion temperature.
    [0008]
    8. Manufacturing method according to one of the preceding claims, characterized in that the step of fixing the fiber to the envelope at the passage openings comprises a bonding of the fiber at the locking points. 10
    [0009]
    9. Manufacturing method according to one of the preceding claims, characterized in that it further comprises fixing the fiber sensor (2) to the casing (10) at at least one connecting zone (171). ).
    [0010]
    10. Manufacturing process according to claim 9, characterized in that the attachment of the sensor (2) to the casing (10) at at least one connecting zone (171) is achieved by gluing.
    [0011]
    11. Manufacturing method according to one of the preceding claims, characterized in that the step of positioning the optical fiber sensor comprises the longitudinal positioning of the optical fiber sensor substantially in the middle of the envelope. 20
    [0012]
    12. Manufacturing method according to one of the preceding claims, characterized in that the sensor is a hydrophone.
    [0013]
    An optical fiber sensor device (1), comprising an envelope (10) delimiting a cavity (3), an optical fiber sensor (2), said optical fiber sensor comprising an optical fiber (12) and a device holding (11) integral with the optical fiber, said holding device being traversed by the optical fiber 3034207 between two fixing points provided on said holding device, characterized in that the optical fiber (12) passes through the envelope at level of two passage openings (130, 140) provided on the casing (10) and extends generally along a longitudinal axis in said cavity (3), which defines two portions of optical fibers of given lengths in the envelope, on either side of the holding device (11), each fiber portion extending between one of said fixing points of the holding device (11) and the passage opening (130, 140) of the envelope (10) on the same side of the fiber sensor optical fiber (2) and being substantially in a straight line, each fiber portion comprising a distension such that the length of each fiber portion extending between a fastening point of the holding device and a passage opening of the envelope is greater than the geometric distance between said attachment point of the holding device (11) and said passage opening.
    [0014]
    Sensor device according to claim 13, characterized in that the wavelength of the light passing through the optical fiber of the sensor device is a linear function of a stretch parameter corresponding to a stretch applied to the device. sensor, said linear function having a slope break for a critical value of the stretching parameter such that the directing coefficient of the linear function after said critical value is greater than the directing coefficient of the linear function before said critical value.
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    同族专利:
    公开号 | 公开日
    EP3274670A1|2018-01-31|
    US20180073916A1|2018-03-15|
    SG11201707915PA|2017-10-30|
    FR3034207B1|2018-01-19|
    SG10201908843PA|2019-11-28|
    US10627284B2|2020-04-21|
    AU2016239915B2|2021-07-29|
    AU2016239915A1|2017-10-26|
    EP3274670B1|2022-02-16|
    WO2016156197A1|2016-10-06|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2010123566A1|2009-04-22|2010-10-28|Lxdata Inc.|Pressure sensor arrangement using an optical fiber and methodologies for performing an analysis of a subterranean formation|
    WO2010136723A1|2009-05-29|2010-12-02|Ixsea|Fiber bragg grating hydrophone comprising a diaphragm amplifier|
    WO2012140179A1|2011-04-14|2012-10-18|Thales|All-optical hydrophone that is not sensitive to temperature or static pressure|
    CN102288226B|2011-07-29|2013-02-06|中国科学院光电技术研究所|Multi-state gas-liquid optical fiber sensor for detecting pressure intensity, temperature and component concentration simultaneously|
    GB0119033D0|2001-08-03|2001-09-26|Southampton Photonics Ltd|An optical fibre thermal compensation device|CN108627236A|2018-03-29|2018-10-09|北京航天控制仪器研究所|A kind of silicon substrate diaphragm type fiber laser hydrophone|
    FR3080175B1|2018-04-13|2020-03-20|Commissariat A L'energie Atomique Et Aux Energies Alternatives|DEFORMATION MEASUREMENT OPTICAL FIBER SENSOR OPERATING IN A SEVERE ENVIRONMENT|
    CN111399034B|2020-03-31|2021-03-16|武汉理工大学|Hydrophone detection device and method based on low bending loss chirped grating array|
    CN112526588B|2020-11-10|2022-02-22|广东工业大学|Common-centroid double-disc differential type optical fiber vector seismometer|
    CN112433244B|2020-11-10|2022-02-22|广东工业大学|Common-centroid push-pull type three-component optical fiber seismometer|
    法律状态:
    2016-02-23| PLFP| Fee payment|Year of fee payment: 2 |
    2016-09-30| PLSC| Publication of the preliminary search report|Effective date: 20160930 |
    2017-02-27| PLFP| Fee payment|Year of fee payment: 3 |
    2018-02-27| PLFP| Fee payment|Year of fee payment: 4 |
    2020-02-27| PLFP| Fee payment|Year of fee payment: 6 |
    2021-02-25| PLFP| Fee payment|Year of fee payment: 7 |
    2022-02-21| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1500613|2015-03-27|
    FR1500613A|FR3034207B1|2015-03-27|2015-03-27|FIBER OPTIC SENSOR DEVICE|FR1500613A| FR3034207B1|2015-03-27|2015-03-27|FIBER OPTIC SENSOR DEVICE|
    SG10201908843P| SG10201908843PA|2015-03-27|2016-03-24|Optical-fibre sensor device|
    US15/561,056| US10627284B2|2015-03-27|2016-03-24|Optical-fibre sensor device|
    EP16713817.1A| EP3274670B1|2015-03-27|2016-03-24|Method of manufacturing an optical-fibre sensor device|
    AU2016239915A| AU2016239915B2|2015-03-27|2016-03-24|Optical-fibre sensor device|
    SG11201707915PA| SG11201707915PA|2015-03-27|2016-03-24|Optical-fibre sensor device|
    PCT/EP2016/056539| WO2016156197A1|2015-03-27|2016-03-24|Optical-fibre sensor device|
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