FR2564985A1 - Method for making a connection between two optical fibres, product obtained by this method and device for the implementation of the method - Google Patents

Abstract

The present invention relates to a method for making a connection between two optical fibres, as well as the connection device obtained by this method and the device for the implementation of the method. According to the method for making the connection, in a first phase, the extremity 3' of a first optical fibre 3 is immobilised in a first ferrule 1 which is itself immobilised, along the axis of an end part 5' of a tube 5, by means of a curable filling material. During the second phase, the extremity 4' of the second optical fibre 4, surrounded by a second ferrule 2, is inserted into the second end part 5'' of the tube 5, then displacement elements are brought, through transverse orifices 7' traversing the wall of the tube 5, to bear against the ferrule 2. During the third phase, the displacement elements are actuated radially to the tube until the cores of the two fibres 3 and 4 are aligned, this alignment being optimised when a detector, coupled to one of the fibres, detects the end value of a signal, injected by coupling, in the other fibre. A curable filling material 6 is then poured into the second end part 5'' of the tube 5, around the ferrule 2, and the displacement elemente are withdrawn from the orifices 7'. This method enables either a splice or a connector to be obtained.

Description

 The present invention relates to a method of making a connection between two optical fibers, in which, before being immobilized end to end with respect to each other, the hearts of the two fibers are aligned with each other using a measuring instrument intended to detect, on one side of the connection point, in one of the fibers, an extreme value resulting from a signal injected into the other fiber towards the connection point, this extreme value corresponding to optimum alignment of the hearts of the two optical fibers.

 In methods of making a connection between two optical fibers, known of this kind, such as that described in French patent N 2 524 989, the end portions of the two optical fibers, which are stripped only on 0.5 Eìl approximately long, are each placed in a vacuum mandrel on a movable stage. The fiber sheaths are initially aligned with each other using a microscope, then a longitudinally split cylinder, filled with a special cement, is placed on a grooved support which moves it upwards by means of a movable stage, so to surround the connection point without touching it. The fibers hearts are then precisely aligned using a scattered radiation detector, which is coupled on one of the fibers and must observe a radiation directed axially given the heart of the other fiber towards the first. When the alignment is perfect between the two extreme parts of the optical fibers, the cement is hardened by exposure of a few seconds to ultraviolet radiation.

 Such a process is difficult to implement, especially on an outdoor site, because the fibers having a very small outside diameter (about 120 μm), they are therefore difficult to handle, all the more so since they are always both at the same time, which requires the use, for each of the two optical fibers, of temporary positioning means and means of movement in space, very precise. Added to this is the presence of the split cylinder filled with cement, which requires the use of a grooved support that can be moved vertically with great precision as well. All material, which must therefore be very stable, is not compact and, s '' it can be easily manipulated in the laboratory, it is not the same on a construction site, all the more so since it is also necessary to use other delicate materials: microscope, emitter of ultraviolet rays for harden the cement .., An additional disadvantage lies in the fact that the method is only intended to achieve a "splice", ctestwàdire a fixed connection that can not be disconnected and reconnected, even once.

 The production method according to the invention is characterized in that the end part of the first optical fiber, whether or not surrounded by a tip, is at least approximately centered inside a first end part of a tube, before being immobilized in this first end part then the end part of the second optical fiber, surrounded by a tip of which it is integral, is introduced axially into the tube and its end is brought into contact with the end of the first fiber The end of the second optical fiber is then moved in a plane perpendicular to the axis of the first fiber, until the end of its core is exactly aligned with that of the core of this first optical fiber, this position being obtained when the measuring instrument detects the extreme value. The second optical fiber is then immobilized in a fixed position relative to the tube, by a hardened filling sand material introduced into the tube around the nozzle.

 According to one embodiment, the second optical fiber is moved in a plane perpendicular to the axis of the first fiber, by systematically exploring a predetermined surface, at least until the measuring instrument detects the extreme value. According to another embodiment, the predetermined surface is explored by trial and error.

 According to one embodiment, in order to exactly align the hearts of the two optical fibers, the end piece surrounding the second fiber is displaced transversely by mechanical displacement elements introduced temporarily radially through orifices respectively passing through the wall of the tube. According to another embodiment, the end of the core of the second optical fiber is first centered with the end of the core of the first fiber, by mechanical displacement elements acting on the front part of the end piece of the second fiber, then the rear part of the same end piece is moved radially by mechanical displacement elements, in order to align the whole end part of the core of the second optical fiber, with the end part of the core of the first fiber.

 The present invention makes it possible to obtain a method of making a connection between two optical fibers, which, while allowing alignment of the cores themselves of the two optical fibers, is less difficult to implement than in the known prior art, even on an exterior site, by the fact that the end parts of the two fibers are less fragile and less delicate to handle, and by the fact that the displacement means are more compact and are simplified since they are advantageously provided for displacing a only one of the two optical fibers, in one plane only. An additional advantage lies in the fact that this method makes it possible to achieve at will not only a splice, but also a connector, the two parts of which, whether or not they are paired together, can be connected and disconnected several times without harming the alignment obtained between the cores of the two optical fibers.

 The present invention also relates to a connection device for optical fibers, produced by the method according to the present invention. This device comprises two optical fibers, the end part of at least one of which is surrounded by a tip to which it is integral, these optical fibers being held end to end in a common tube.

 In connection devices, known of this kind, such as that described in French patent No. 2,524,988, two end caps each containing the end part of a fiber are each disposed with play in an axial bore provided in a body which comprises four regularly distributed transverse passages, each containing a ball which is driven there, in abutment against the corresponding endpiece Two bodies are arranged facing this in a tube containing in its central part an axially pierced sphere of which two opposite parts are provided to serve each as a support for a hollow frustoconical part provided at the front of each of the bodies. A spring constantly pushes each body against the sphere. The transverse adjustment of the axis of each end part of optical fiber surrounded by its tip is carried out in a caliber similar to a half-tube provided with a re sphere opposite which is placed a self-adhesive bezel aligned with the center of said sphere. displaced transversely in the corresponding passages, by moving the endpiece themselves, until the alignment of the optical fiber with the reticle of the telescope is obtained.

 Such a device has drawbacks, regardless of its relative complexity, because it requires that the sphere be executed with extreme precision, both in terms of its geometric shape and its diameter. The slightest defect in these areas causes a relative offset of the two optical fibers and / or an irregular spacing of the ends of the two fibers. In addition, a defect in transverse positioning of the sphere in the tube causes a misalignment of the axes of the two optical fibers.

 The embodiment device, according to the invention, is characterized in that it comprises access orifices, distributed at the periphery of the tube, extending radially through the wall of the tube and, up to the end piece which It is housed there, through a hardened filling material placed in the tube around the end piece and the two optical fibers, these orifices being dimensioned to allow the passage of the mechanical displacement elements.

 According to an alternative embodiment, the tube comprises, around at least one end piece, a first group of access orifices arranged in the immediate vicinity of the front part of the end piece, part surrounding the end of the fiber to be connected , and a second group of access ports arranged at the other end of the end piece.

 According to one embodiment, the end part of a first optical fiber is precisely centered in the first end part of a tube and constitutes with this tube a gauge for the successive production of end pieces, surrounded or not surrounded by hardened filling material, end caps respectively surrounding the end part of second optical fibers whose core is, in each case, aligned with that of the first optical fiber, the tube being integral with the gauge or each of said end pieces.

 The present invention thus proposes to allow the realization of a connection device for optical fibers, of simple structure and compact, ensuring, in the case where it constitutes a connector, a constant alignment of the hearts of the two optical fibers after several successive connections and disconnections.

 The present invention also relates to a device for implementing the production method. This device is characterized in that it comprises two devices of slow advance, arranged to cooperate respectively with two displacement elements arranged at least approximately 90 "from each other relative to the location of the tube, these two displacement elements being kinematically linked with the corresponding end piece. At least one of the two displacement elements is intended to be actuated by an oscillation device intended to cause it to oscillate, at rapid rate, by an equal distance to a transverse dimension of the surface to be explored, while the other displacement element is actuated by its slow advance device, over a distance equal to the other transverse dimension of the surface to be explored, or at least up to the measuring instrument detects the extreme value.

 The accompanying drawing illustrates, by way of example, different embodiments of connection devices according to the invention, shows tees at different stages of embodiment.

 Fig. 1 shows, seen in longitudinal section, a first connection device, after its first phase of production.

 Fig. 2 shows, seen in longitudinal section, a variant of the same first connection device, also after its first phase of production.

 Fig. 3 shows, seen in longitudinal section, the same first connection device, during its second phase of production.

 Fig. 4 shows, seen in section along IV-IV of FIG. 3, the same first device during its second production phase, as well as, schematically, the device for implementing the production method.

 Fig. 5 schematically represents the emitter-detector assembly, coupled on the two optical fibers to be connected together.

 Fig. 6 shows, seen in longitudinal section, the same first positive connection device obtained after the third and last phase of realization.

 Figs. 7 and 8 show, seen in longitudinal section, a second embodiment of the connection device, at two successive stages of its third embodiment.

 Fig. 9 represents, seen in section along IX-IX of FIG. 10, a third connection device constituting a connector, shown during its third phase of production.

 Fig. 10 represents, seen in section along X-X of FIG. 9, the same third embodiment of the device.

 Fig. It represents, seen in longitudinal section, a fourth embodiment of the connection device, after its third phase of production.

 Fig. 12 schematically represents the transmitter-detector assembly, used for the production of the fourth embodiment of the connection device.

 Fig. 13 shows, seen in longitudinal section, the fourth embodiment of the connection device, constituting a connector.

 As shown in fig. 6, a connection device, in accordance with the present invention, comprises two end pieces I, 2, each comprising a longitudinal channel in which is threaded an end portion, respectively 3 ', 4t, of an optical fiber, respectively 3, 4, whose protective sheath has been previously removed over a length greater than that of the end piece. Each end part 31, 4 ′ St glued by temple in its channel and arrives flush with the end of the corresponding end piece.

The two optical fibers 3, 4 and the end caps 1, 2 which surround them are permanently fixed face to face in a common tube 5, by a hardened filling material 6 which is placed in the tube 5 around the end caps 1, 2. This connection device comprises two groups of access orifices 7, 7 ', each comprising for example four orifices distributed regularly at the periphery of the tube 5. These orifices 7, 7' extend radially through the wall of the tube S and sct p olonges through the hardened filling material 6 to the end piece 1, 2 which is housed therein. These orifices 7, 7 'are dimensioned to allow the passage of mechanical displacement elements used for the manufacture of said device connection which constitutes a splice, in this example.

 According to one embodiment of the invention, the tube 5 has a length of 20 to 30 mm and an outside diameter of 5 mm, the outside diameter of the end pieces 1, 2 being approximately 3 mm.

 To make such a connection device, the end part 3 ′ of the first optical fiber 3 is first approximately centered inside a first end part 5 ′ of the tube 5. For this, as shown in FIG. 1, this end part 3 ', surrounded by a first end piece 1 in this example, is introduced axially into the first end part 5', and four mechanical displacement elements 8 are introduced radially through the four access ports 7 respectively provided in the first end part 5 ', to center approximately the first end piece 1 and the first end part 3' of the fiber 3. A hardenable filling material 6 is then introduced into the first end part 5 'of the tube 5 around the first tip I only. When this material is hardened, the mechanical displacement elements 8 are removed from the access orifices 7. The first tip 1 and the corresponding optical fiber 3 are thus fixed permanently in the tube 5, this first phase being able to be advantageously carried out in advance, in the workshop.

 Fig. 2 represents an alternative embodiment of this first phase, in which the extreme part 3 ′ of the first optical fiber 3 is embedded directly in the hardenable material 6, without the intermediary of a first end piece 1.

 During the second phase of production, shown in FIG. 3, the end part 4 ′ of the second optical fiber 4, surrounded by a second end piece 2 of which it is integral, is introduced axially into the second end part 5 ″ of the tube 5, and its end is brought into contact with the end of the first optical fiber 3. The assembly is then arranged, as shown in Fig. 4, between four mechanical displacement elements 8a, 8b, 8c, 8d supported by a fixed support not shown in the drawing, these displacement elements being introduced into the access orifices 7> until it comes to bear on the periphery of the second end piece 2, while the tube 5 is kept fixed. On the other hand, an optical fiber 3a is coupled to the optical fiber 3 at the output of a signal transmitter 11, for example emitting optical radiation, and, to the optical fiber 4, is coupled an optical fiber 4a connected to the input of a measuring instrument constituted for example by a detector of scattered radiation 12, as described in the cited prior art previously. Radiation is thus injected into the optical fiber 3a and the detector 12 can detect a minimum scattering of this radiation at the connection point (fig. 5).

 The third phase, proper alignment, can then begin: the extreme part 4 ′ of the second optical fiber 4 is then moved in a plane P (fig. 3) perpendicular to the axis of the first optical fiber 3, by the displacement elements 8a, 8b, 8c, 8d which can be actuated only by cranks not shown in the drawing. This movement takes place, for example by trial and error, until the end of the heart of the second fiber 4 is perfectly aligned with that of the heart of the first fiber 3, this optimum position being obtained when the detector 12 detects a extreme value of the radiation, which corresponds, in this example, to a minimum diffusion. The second fiber 4 is then immobilized in the position thus obtained, by the curable filling material 6 introduced into the tube 5 around the end piece 2. When this material 6 is hardened, the displacement elements 8a, 8b, 8c, 8d are removed from the access ports 7 '. The connection device shown in fig. 6, constituting a splice, is thus produced.

Without departing from the scope of the present invention, the search for the optimum range of the second fiber relative to the first fiber 3 could be carried out by systematically exploring a predetermined area, until the detector 12 detects the value extreme
In the alternative embodiment of the connection device, shown in FIGS. 7 and 8, the first fiber 3 is immobilized in the tube 5, for example as described previously with reference to FIG. 2.The tube 5 further comprises, around the end piece 2 surrounding the end part 4 of the second optical fiber 4, a first group of access orifices 17 arranged in the immediate vicinity of the front part of the end piece 2, part surrounding the end of this second fiber 4, and a second group of access orifices 17 ′ arranged at the other end of the end piece 2.

 Thus, during the third alignment phase, the end of the core of the second optical fiber 4 is first centered with the end of the core of the first optical fiber 3, by four mechanical displacement elements 18 acting on the front part of the end piece 2 of the second fiber 4 (fig. 7). Then the rear part of the same end piece 2 is displaced radially by four mechanical displacement elements 18 ′, in order to align the entire end part 4 ′ of the core of the second optical fiber 4 with the end part 3 ′ of the core of the first optical fiber 3 (fig. 8). This not only provides a centering of the two hearts, but an alignment of all of the end parts 3 ', 4'. The rest of the production process remains unchanged.

 According to another embodiment, the connection device constitutes a connector such as that shown for example in FIGS. 9 and 10.

In this embodiment, the end part 3 'of the first optical fiber 3 is immobilized at least approximately along the axis of the first end part 5' of the tube 5, for example as described previously with reference to FIG. 5, by the hardened filling material 6 which makes it integral with the tube 5.

 On the other hand, the second end piece 2 surrounding the end part 4 'of the second optical fiber 4 is integral with the hardened filling material 6' which surrounds it, which is itself separable by sliding from the end part 5 " internal of the tube 5 and of the hardened filling material 6 surrounding the end part 3 ′ of the other optical fiber 3. A profiled positioning part, constituted for example by a longitudinal groove 13. is provided inside the tube 5 To position the tip angularly, the hardened filling material 6 ′ surrounding the second / Z, relative to the tube 5, in a single relative angular position.

 The second extreme part 5 "of the tube 5 advantageously comprises an external thread 14 with which the internal thread of a threaded plug 15 is engaged through an axial orifice 15t from which the second optical fiber 4 passes. A recess 16, of more diameter larger than the inside diameter of the tube 5, is provided in this plug The filling material 6 'at least partially fills this plug 15 which thus serves to disconnect and reconnect the second end piece 2 and the hardened material 6' which i ' around the tube 5.

 The process for producing this connector is identical to that of crit previously (fig. 1 to 6), with one exception. Indeed, just before the second end piece 2 is centered in the second end part 5 "of the tube 5, by the displacement elements 8a, 8b, 8c, 8d, the interior of this first end part 5" is covered with a non-stick material, as well as the interior of the threaded plug 15 which is threaded onto the second optical fiber 4.

 Note that the two parts of such a connector are paired together during their production and that, therefore, the interior of the tube 5 does not need any manufacturing precision.

 According to a variant of this connection device, shown in FIG. 11, the end piece 2 can be separated by sliding, from the hardened filling material 6 'which surrounds it, which is itself integral with the inner periphery of the tube 5 and the hardened filling material 6 surrounding the end part 3 'of the other optical fiber 3. The groove 13 (fig. 9) is replaced by a groove 13a provided longitudinally on the end piece 2, to angularly position this end piece 2 relative to the hardened filling material 6' which l surrounds, in a single relative angular position.

 The threaded plug 15 (fig. 9) is replaced by a threaded plug 15a having no recess 16. The bottom of this plug, drilled in 15 'to allow the second optical fiber 4 to pass, is in abutment against the former. rear end of the nozzle 2 which protrudes out of the tube 5.

 The process for producing this connector is similar to that described above (fig. 9 and 10), with one exception. Indeed, it is the end piece 2 which, before being be center in the second extreme part 5 ", is coated with an anti-adhesion material, instead of the inside of the tube 5. As in the case previous (fig. 9, 10), the two parts of the connector are paired together.

 According to another embodiment of a connection device, the extreme part 3 ′ of the first optical fiber 3 is, as previously described with reference to FIG. l, centered in the first extreme part 5 ′ of a tur be 5, more precisely with respect to the inner periphery of said tube. In this case, this centering is carried out with the greatest precision, the extreme part 3 'constituting, with the tube 5, a gauge for the successive production of tips 2, 2A, or ... surrounded (fig. 9) , or not (fig. 11), of hardened filling material 6 ′, these end pieces respectively surrounding the extreme part 4 ′ of second optical fibers 4, 4A, 4B. The tube 5 is either secured to the gauge, or secured to each of the end pieces 2 produced successively with this gauge.

 The core of the second fibers 4 is thus, each time, aligned with that of the first optical fiber 3 of the caliber, then immobilized, using the method described above with reference to FIGS. 9, 10, respectively 11. For the execution of this method, during its second phase, the first optical fiber 3 is advantageously connected, as shown in FIG. 12, directly at the output of the signal transmitter 11 which directly injects cptic radiation into this first optical fiber 3 and into the connection point.

 I1 is thus possible to obtain for example a connector such as that shown in FIG. 13, in which the killed 5 is secured to an optical fiber 4A by the intelmedia re of a tip 2A, this assembly having been obtained using the caliber described above. The other etreme part 5 "of the tube 5, provided with a groove 13, receives by flow another optical fiber 4B surrounded by an elniout 2B and hardened filling material 6 ′, as described above in FIG. 9. A threaded plug 15 makes it possible to connect and disconnect the optical strip 4B. This assembly was also obtained with a gauge whose tube 5 had a 5 "end threaded to receive the threaded plug 15.

 The two parts of such a connector are no longer paired together, but produced from a single gauge. The only precision required is that of the internal diameter of the tubes 5 used.

 The device for implementing the production method, which is also the subject of the present invention, comprises, as shown diagrammatically in FIG. 4, two slow advance devices 21, 22 arranged to cooperate respectively with two mechanical displacement elements 8a, 8b arranged at least approximately 900 from one another with respect to the location of the tube. These slow advance devices 21, 22 are designed to move the displacement elements 8a, 8b radially to the tube in two opposite directions 23, 24, respectively 25, 26. They are constituted, for example, by cranks or by stepper motors. not.

 The two displacement elements 8a, 8b are kinematically linked with the corresponding end piece 2 (fig. 4), for example by two other mechanical displacement elements 8c, 8d, diametrically opposite the first two 8a, 8b, relative to the tube, pushed by elastic means 27 bearing against the end piece 2.

 At least one of the first two displacement elements 8a, 8b is intended to be actuated by an oscillation device 28 provided to cause it to oscillate at a rapid rate, by a distance equal to a transverse dimension, width for example, of the surface to be explored. It is the element 8a which is thus liable to oscillate rapidly, along 23 then 24, over a width of Q, l mm for example. The oscillation device 28 can consist essentially, for example, of an electromagnetic mechanical system, a quartz, a tuning fork.

 While the oscillation device 28 thus oscillates at a fast rate alternately along 23, 24, the displacement element an and the end piece 2, the slow advance device 22 slowly displaces the displacement element 8b and the same tip 2, first along 25 until the detector 12 (fig. 5.7) has detected an extreme value, then along 26 to return to the point corresponding to this extreme value. It is then the turn of the other slow advance device 21 to move alone along 23, at slow speed, until the detector 12 also detects an extreme value, the displacement element 8a and the end piece 2 The centering Dp timun of the two fibers 3 and 4 is thus obtained.

 Without departing from the scope of the present invention, the successive operations. first of the slow advance device 22 and of the os- ù'avrtce, cillation 28 device, then of the other slow device 21, can between commands by an electronic system capable in addition of successively memorizing the optimum positions corresponding displacement elements 8b and 8a, positions in which the detector 12 detects extreme values, then to return to these positions.

Claims (11)

1. Method for making a connection between two optical fibers (3,  4), in which, before being immobilized end to end one relative  to the other, the hearts of the two fibers are aligned with each other using  sant a measuring instrument (12) intended to detect, on one side of the  connection point, in one of the fibers, an extreme value resulting  of a signal injected into the other fiber towards the con point  nexion, this extreme value corresponding to an optimum alignment of  hearts of the two optical fibers, characterized in that the extrem  me (3 ') of the first optical fiber (3) is at least approximately  centered inside a first end part (5 ') of a tube (5),  before being immobilized in this first extreme part, then the  extreme part (4 ') of the second optical fiber (4), surrounded by a  end piece (2) of which it is integral, is introduced axially into the  tube (5) and its end is brought into contact with the end of the  first optical fiber (3), the end of the second optical fiber (4)  then being moved in a plane (P) perpendicular to the axis of the pre  fiber (3) until the end of its core is exactly  aligned with that of the core of this first optical fiber (3), this  position being obtained when the measuring instrument (12) detects the  extreme value, the second optical fiber (4) then being immobilized  in a fixed position relative to the tube (5), by a hardened material  filling sand (ó) introduced into the tube (5) around the nozzle (2). 2. Production method according to claim 1, characterized in that  the second optical fiber (4) is moved in a perpendicular plane  (P) to the axis of the first fiber (3), exploring systematically  only a predetermined area, at least until the instrument  measure (12) detects the extreme value. 3. Production method according to any one of claims l or  2, characterized in that, to exactly align the hearts of the two  optical fibers (3, 4), the end piece (2) surrounding the second fiber (4) is  moved transversely by mechanical displacement elements (8a,  8b, 8c, 8d) temporarily introduced radially through respective  orifices (7t) passing through the wall of the tube (5). 4. Production method according to any one of claims 1 or  2, characterized in that the end of the core of the second optic fiber  that (4) is first centered with the end of the heart of the first fi  optical bre (3), by mechanical displacement elements (18) acting  on the front part of the end piece (2) of the second fiber (4), then  the rear part of the same end piece (2) is moved radially by é  mechanical displacement links (18 '), to align the entire part  end (4 ') of the core of the second optical fiber (4) with the ex part  treme (3 ') of the core of the first optical fiber (3). 5. Connection device for optical fibers, produced by the se-  lon any one of claims 1 to 4 comprising two fibers  optics (5, 4) of which the extreme part (3t, 4 ') of at least one is  surrounded by a tip (1, 7 to which it is integral, these fibers being  held end to end in, -m common tube (5), characterized in that it  has access openings (7, 7 ';; 17, 17'), distributed around the periphery  of the tube (5), extending radially through the wall of the tube and, jus  than at the nozzle (1, 2) which is housed therein, through a filled material  hardened sage (6) arranged in the tube around the end piece (1, 2) and  two optical fibers, these orifices being sized to allow the  passage of the mechanical displacement elements (8a, 8b, 8c, 8d; 18, 18 '). 6. Connection device according to claim 5, characterized in that  the tube (5) comprises, around at least one end piece (2), a first groove  eg access ports (; 7) arranged in the immediate vicinity of the part  front of the end piece (2), part surrounding the end of the fiber (4) to  connect, and a second group of access ports (17 ') arranged at the other  be at the end of the end piece (2). 7. Connection device according to any one of claims 5 or  6, characterized in that two end pieces (1, 2) each surrounding the part  end (3 ', 4') of an optical fiber (3, 4) are permanently fixed facing  face in the tube (5) with a hardened filling material (6) available  around them. 8. Connection device according to any one of claims 5 or  6, characterized in that at least one end piece (2) surrounding the ex part  treme (4 ') of an optical fiber (4) is integral with the hardened filling material (6') which surrounds it, which is itself separable, by  sliding, of the corresponding internal part (5 '') of the tube (5) and  the hardened filling material (6) surrounding the extreme part (3 ')  of the other optical fiber (3), at least one profiled position part  ment (] 3) being provided inside the tube (5), to position an  the hardened filling material (6 ′) surrounding the end piece (2),  relative to the tube (5), da, ls a single relative angular position. 9. Connection device according to any one of claims 5 or  6, characterized in that at least one end piece (2) surrounding the ex part  trême (4 ') of an optical fiber (4) is separable, by sliding, from the  hardened filling material (6 ') which sssourour5 which is itself so  lidaire of the inner circumference of the tube (5) and the end part (3 ')  of the other fiber (3), at least one profiled positioning part  (13a) being provided on the periphery of the end piece (2), to position atr  this nozzle (2) with respect to the hard filling material  cie (6 ') which surrounds it, in a single relative angular position. 10. Connection device according to any one of claims 8 or  9, characterized in that the end part (3 ') of a first op fiber  tick (3) is precisely centered in the first extreme part  (5 ') of a tube (5) and constitutes, with this tube, a gauge for the reaction  successive insertion of end caps (2A, 2B ...) surrounded or not by material  hardened filling (6 '), end caps respectively surrounding the ex  very second optical fibers (4a, 4b) whose core is, each  times, aligned with that of the first optical fiber (3), the tube (5)  being integral with the caliber or each of said ends (2A).  measurement detects the extreme value.  across the surface to be explored, or at least until the instrument  tif of slow advance, over a distance equal to the other trans dimension  while the other displacement element is actuated by its arrangement  distance equal to a transverse dimension of the surface to be explored,  tif of oscillation intended to make it oscillate, at a rapid rate, by a  displacement elements being provided to be actuated by a arranged  kinematically linked with the corresponding nozzle, at least one of the two  relative to the location of the tube, these two displacement elements being  cement arranged at least approx. 90 relative to each other by  22), arranged to cooperate respectively with two displacement elements  characterized in that it comprises two slow advance devices (21,  11. Device for implementing the method according to claim 2,