Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/38—Mechanical coupling means having fibre to fibre mating means
  • G02B6/3807—Dismountable connectors, i.e. comprising plugs
  • G02B6/3833—Details of mounting fibres in ferrules; Assembly methods; Manufacture
  • G02B6/3855—Details of mounting fibres in ferrules; Assembly methods; Manufacture characterised by the method of anchoring or fixing the fibre within the ferrule
  • G02B6/3857—Crimping, i.e. involving plastic deformation
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/32—Optical coupling means having lens focusing means positioned between opposed fibre ends
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/38—Mechanical coupling means having fibre to fibre mating means
  • G02B6/3807—Dismountable connectors, i.e. comprising plugs
  • G02B6/3833—Details of mounting fibres in ferrules; Assembly methods; Manufacture
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/38—Mechanical coupling means having fibre to fibre mating means
  • G02B6/3807—Dismountable connectors, i.e. comprising plugs
  • G02B6/3833—Details of mounting fibres in ferrules; Assembly methods; Manufacture
  • G02B6/3855—Details of mounting fibres in ferrules; Assembly methods; Manufacture characterised by the method of anchoring or fixing the fibre within the ferrule
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/3628—Mechanical coupling means for mounting fibres to supporting carriers
  • G02B6/3632—Mechanical coupling means for mounting fibres to supporting carriers characterised by the cross-sectional shape of the mechanical coupling means
  • G02B6/3644—Mechanical coupling means for mounting fibres to supporting carriers characterised by the cross-sectional shape of the mechanical coupling means the coupling means being through-holes or wall apertures
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
  • G02B6/4207—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback
  • G02B6/4208—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback using non-reciprocal elements or birefringent plates, i.e. quasi-isolators
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4248—Feed-through connections for the hermetical passage of fibres through a package wall

Definitions

• the present invention relates to a method and a device for securing an optical component to a mechanical structure.
• the technical field of the invention is that of the manufacture of optical systems, in particular those based on optical fibers.
• the present invention applies to all types of optical components, whatever their dimensions and their geometry, in particular to all components of cylindrical, spherical or parallelepiped shape, in particular to lenses, microlenses (whose diameter is of the order of millimeter or less), windows, optical fibers (whose diameter is of the order of one or several hundred microns), optical fiber collimators, filters, mirrors and isolators. It also applies to components arranged in parallel or in a matrix such as fiber sheets and lens arrays.
• optical components In many optical systems, it is necessary to align and fix optical components permanently.
• systems providing optical or optoelectronic functions such as transmitters, receivers, “switches”, wavelength multiplexers / demultiplexers, circulators, “interleavers”, attenuators and amplifiers, are provided for integration permanently (until the end of their life) in a fiber optic network, which is buried (in the case of terrestrial links) or placed under the sea (in the case of submarine links).
• the various optical elements that make up these systems must therefore be aligned and permanently fixed. One must therefore avoid any untimely misalignment, leading to performance drift over time. The maintenance of these components must therefore be sufficiently rigid.
• the optical components making it possible, after their alignment with one another, to obtain the desired optical function are positioned in or on (when they pass through with the external environment) of the airtight housings.
• helium or waterproof so as to be free from any contamination or mold problem due to the external environment.
• Some of these optical and optoelectronic systems in hermetic or watertight housings are fitted with an optical fiber, one end of which is located in the housing and the other end is outside the housing, the crossing of the wall of the housing by means of a ferrule in which the optical fiber is mounted.
• the hermetically sealed or watertight crossing is formed by a frame comprising other optical components such as lens / fiber end sub-assemblies. In all cases, airtightness or tightness must therefore be ensured between the component mount and the housing, but also between the component and its mount.
• optical systems are manufactured in large quantities, which requires producing these systems with simple and inexpensive techniques, possibly automating production, while maintaining adequate optical performance and ensuring where necessary a hermetic or watertight fixing.
• the invention applies to many optical components, including lenses, optical fibers, filters, optical fiber collimators, insulators, windows, mirrors, lens arrays and fiber layers; the invention also applies to the assembly of several components such as an optical fiber and a lens, two lenses, a collimator and a wavelength filter.
• Fixing by gluing is difficult to implement automatically; in addition, constituents of the adhesive can contaminate the optical component and / or its frame, as well as other components located near the glued part. However, certain optical components (laser diodes and photo detectors for example) are liable to deteriorate under the action of these constituents. In addition, this fixing technique does not ensure a perfectly hermetic connection between the component and its mount; however the use of these components and optical fibers to form telecommunication systems often requires ensuring, for such a connection, a hermetic seal with helium.
• such components and optical fibers can be metallized at their periphery and then brazed into the frame (using a binder); this method of fixing by brazing is expensive and difficult to implement in an automated manner.
• the present invention aims to provide a method and a device for solid and final fixing of such components and optical fibers to a structure, for the production of a fiber optic connector for example, or of a bulkhead crossing, which at least partially remedy the known drawbacks of techniques for fixing such components.
• An object of the invention is to propose such a method and device which are inexpensive, easily automated, simple, quick and easy to implement, usable for various types of components, and not requiring the use of components and frames whose geometry respects excessively tight dimensional tolerances.
• Another objective of the invention is to propose a device which, if necessary, makes it possible to ensure a hermetic seal with helium or a water tightness between the component and the mechanical structure in order to be used as a crossing of hermetic or waterproof wall.
• Another objective of the invention is to propose a device whose manufacturing and assembly parameters are controllable.
• Another objective of the invention is to propose methods and device allowing a good alignment of the component in its frame.
• the component in order to fix an optical component to a structure, the component is engaged in a deformable frame, which is deformed, generally by compression, until it is fixed to the component, and the frame deformed by a ring encircling the frame; we can then fix the frame or the ring to the structure.
• the invention applies to a method of fixing an optical component in a cavity provided in a first part - called a mount -, by deformation of the first part and constricted of the cavity until obtaining a fixing by friction of the component on a face of closed contour, in particular a cylindrical face delimiting in part at least the cavity.
• a second part comprising - or essentially constituted by a ring which encloses the first part so as to cause and / or maintain said constriction, so that the a simultaneous assembly of the component and said first and second parts is carried out by friction of the component with the first part, and by friction of the first part with the second part.
• the second part encloses the first part at (that is to say around) the zone of friction joining between the component and the first part.
• the elastic limit of the material making up the frame is low so that said frame can easily deform.
• the term elastic limit is understood to mean the stretching stress which, when applied to a test, causes a residual elongation (measured once the stress returned to zero) equal to 0.2% of its initial length. It is considered that when the residual elongation is greater than 0.2%, the material is no longer elastic: it has entered a plastic phase. There are other definitions which lead to similar results.
• the relatively hard materials used for the frame may have an elastic limit greater than 15 Mpa (Mega Pascal), or even 50 Mpa, 70 Mpa, 100 Mpa or even 170 MPa.
• said frame is metallic.
• It comprises (or is essentially constituted by) a sleeve having an external face on which are exerted, by the ring, compressive forces making it possible to lead to a radial (and centripetal) deformation of the sleeve (and / or of the frame ); the result of this deformation is that an internal face of the frame is brought into contact with an external face of the optical component, and consequently a friction (and / or wedging) connection between the component and the frame.
• said compression forces are obtained by supports exerted on the outer face of the frame by an inner face of a strapping ring enclosing said sleeve and / or said frame.
• at least one of said external face of the frame or internal of the ring is flared.
• one of said external or internal faces is of substantially conical shape, the other face also being of substantially conical shape and of the same conicity; alternatively, this other face is of cylindrical shape.
• the half-angle at the center of or of said flared or inclined face (s) is less than 45 °, preferably of the order of 0.3 to 10 °, in particular of the order of 0.3 to 3 degrees; in order to facilitate the shrinking of the frame by the pressure exerted by the ring, said frame is preferably produced in a material at least as ductile as that of said ring, in particular in a material based on copper, zinc, iron, aluminum , nickel, lead, tin, indium or plastic and / or a thickness is chosen for said frame at most equal to that of said ring.
• said external face of the frame and said internal face of said ring may be cylindrical.
• said ring causes the shrinking of the frame, that is to say the reduction of its diameter or of its radial dimensions by mutual support of their respective bearing faces (conical or cylindrical)
• said ring is placed coaxially with said frame and is then displaced, preferably by a translational movement along the longitudinal axis (generally coincident with the axis of revolution common to the bearing faces of the mount and the ring) relative to the mount; this movement can be obtained by a press, the punch of which presses on the ring, and the die of which forms a stop for the frame.
• the material and the dimensions of the ring will preferably be chosen to allow the ring a sufficient radial deformation (in the plane perpendicular to its axis of revolution), as soon as the frame comes into contact with the component, in order to absorb part of the stresses and avoid buckling of the frame, its rupture, or even the rupture of the component.
• the shrinking of the frame surrounding the component and allowing their mutual joining can be obtained by cooling said frame; for this purpose, the frame is preferably previously heated in order to expand and to be able to be placed around the component to which it is to be fixed.
• a hot shrinking operation can be carried out: the frame is heated to a temperature such that its expansion is sufficient to insert the optical component. After cooling, the component is trapped in its mount.
• a frame can be engaged around the optical component, the internal face of which is adjusted to slide with reduced play around the component, then engage, around the thin frame, a ring previously expanded by heating. , and sliding with reduced play around the frame; the ring is then constricted, for example by causing it to cool, so that the ring compresses the frame radially against the periphery of the component until the three parts are joined together.
• the invention is based in part on the surprising observation that it is possible to secure the mounting to an optical component by shrinking the mounting and crimping around the component, without altering the substantially the optical characteristics of the component; indeed, contrary to what one could foresee, the mechanical stresses applied to the optical component under the effect of the tightening by hooping of the ring and constricted of the frame, do not lead to a notable modification of the optical characteristics of the component when they are sufficiently weak and / or when they are radial and uniform (case of an optical component of cylindrical or spherical outline for example).
• the invention is also based on the surprising observation that when the cavity of the frame has a shape and dimensions close to the component to be clamped, it is possible to obtain a hermetic seal with helium or a water tightness between the component and said frame and possibly between the ring and the frame, even for small components such as optical fibers (0.125 mm in diameter) or small lenses (often called microlenses when they have diameters of the about 1 mm or even less).
• a frame having a large bearing surface generally cylindrical
• the clamping forces are distributed thereon and so that the mechanical stresses resulting from the shrinking of the frame are reduced ; tests have shown that a length (measured along the longitudinal axis of the component) of the hooping zone of the frame on the component, the value of which lies in a range from 100 to 3000 microns, gives satisfactory results .
• the invention makes it possible to achieve, without soldering or bonding, a precise, reliable mechanical connection with good repeatability, which can be hermetic with helium or waterproof, and which can be used interchangeably for various types of optical components, minimizing the risk of degrading or destroying these components during the implementation of the process.
• FIGS. 1 to 42 are views in longitudinal section along a plane containing the optical axis 1 of the optical component to be fixed to a structure.
• Figures 1 and 2 schematically illustrate a mechanical fastening system of an optical component of a cylindrical envelope, respectively before mounting and after mounting according to the invention.
• FIGS. 3 and 4 each illustrate a variant according to the invention before mounting the system illustrated in FIGS. 1 and 2.
• FIG. 5 schematically illustrates, in a longitudinal section view, the simultaneous assembly of an optical component, a frame and a ring using a press.
• Figure 6 shows an improvement of the assembly system according to Figure 5 adapted to cylindrical mounts and allowing their guidance.
• Figures 7 and 8 illustrate a variant of the system according to the invention respectively before and after mounting in which ring and mount are cylindrical.
• FIGS. 9 to 12 show three exemplary embodiments according to the invention applied to a thick lens of cylindrical contour, the frame or the ring of which comprises a collar.
• Figures 13 and 14 illustrate two examples of a system according to the invention adapted to a thick lens and in which the ring is designed to receive a ferrule or a capillary housing a fiber.
• Figures 15 to 17 show three variants of an embodiment according to the invention applied respectively to a spherical lens, a thin cylindrical lens and a window, in which the frame is provided with a stop for stopping the lens.
• Figures 18 to 21 each illustrate a variant use of the invention for crimping a ring at the end of an optical fiber ( Figures 18 and 19) and between two portions of an optical fiber provided with a sheath protection ( Figures 20 and 21).
• Figures 23 to 25 illustrate embodiments according to the invention in which there is interposed between a lens and its frame a long deformable ring (Figure 22), two short deformable rings (Figure 23), a short deformable ring (Figure 24 ), a short deformable ring, the frame having an annular projection (Figure 25).
• FIGS. 26 to 28 show an adaptation of the principle of the invention to a component of parallelepiped shape.
• FIG. 29 illustrates another adaptation of the principle of the invention to an optical component of parallelepiped shape in which the mount is provided with a cylindrical cavity.
• Figures 30 to 35 show an alternative embodiment of the invention in which the frame is in two parts, Figures 30 to 33 illustrating the application to an optical fiber, Figures 34 and 35 illustrating the application to optical components of parallelepiped shape.
• Figures 36 and 37 show an exemplary embodiment according to the invention in which the frame has three cavities housing three optical fibers.
• FIG. 38 illustrates another alternative embodiment according to the invention applied to three optical fibers in which three mounts are embedded in a wall.
• Figures 39 to 41 illustrate three alternative embodiments of an assembly allowing the attachment and alignment of the end of an optical fiber and a lens.
• FIG. 42 illustrates the use of an assembly according to the invention for making a sealed crossing of an optical fiber through a wall of a sealed housing containing a laser transmitter.
• the optical component 2 with an optical axis 1 comprises a peripheral face 7 of cylindrical shape along the axis 1;
• the mount 3 is of annular shape and has an inner cylindrical face 8 and an outer face 9 of frustoconical shape, extending along the axis 1 and along the half angle 5 of opening (of the cone), the value of which can be 1 or 2 degrees for example;
• the ring 4 is also of annular shape and has an internal face 10, which is of frustoconical shape with axis 1 and half angle 6 whose value is equal to that of the half angle 5;
• the ring 4 has a cylindrical external face 11 of axis 1.
• FIGS. 3 and 4 each represent an alternative embodiment of the invention before mounting applied to an optical component 2 of cylindrical shape and of optical axis 1.
• the ring 4 and the mount 3 are of annular shape.
• the external face 9 of the frame is of frustoconical shape while its internal face 8 is cylindrical.
• the internal 10 and external 11 faces of the ring are cylindrical.
• the diameter of said cylindrical internal face of said ring is between the small and large diameters of the frustoconical external face 9 of said mount 3.
• the frame 3 is of annular shape and its internal 8 and external 9 faces are cylindrical.
• the ring 4 is also of annular shape, its internal face 10 being of frustoconical shape and its external face 11 of cylindrical shape.
• the diameter of said cylindrical external face 9 of said mount is between the small and large diameters of said frustoconical internal face 10 of said ring 4.
• FIG. 5 shows an assembly system for a device similar to that illustrated in FIGS. 1 and 2 but also applies to a device conforming to those illustrated in FIGS. 3 and 4.
• the press 12 comprises a fixed base 13 and a punch 15 movable in translation along the vertical axis 16 relative to the base.
• the optical component 2 and the mount 3 are placed on the base 13, the mount
• axes 1 and 16 are preferably substantially coincident, and the lower planar face (as marked 17 in figure 1) of the frame 3 is placed on a flat annular support surface 14 of the base 13; the ring 4 is engaged by sliding around the frame 3 until it comes into contact, by its internal face coniquelO of the conical external face 9 of the frame 3; the punch 15 is then moved down along the axis 16, its lower end pressing on the upper face 18 of the ring 4; this results in crushing and narrowing of the frame 3 around the optical component 2, and a blockage by jamming (embedding) of the ring 4 around the frame 3, resulting in an irreversible joining of the three parts 2, 3 and 4.
• the frame or the ring can be fixed to the structure.
• a force sensor (not shown) can be inserted between the face 17 of the mount 3 and the face 14 of the base 13, and be connected to an indicator or a signal processing means capable of controlling the stopping of the movement of the punch when the force exerted has reached a predetermined set value.
• the ring when the ring is metallic, its geometry and its dimensions can be chosen so that the stresses imposed on it for a given depression are greater than the elasticity threshold of the material of which it is made; the stresses on the component and its mounting are therefore not very dependent on the tolerances on their respective diameter (s), that of the ring and the angles of the cones, if any.
• the stresses imposed by the ring on the frame and on the component can thus be included in a range ensuring the desired mechanical strength and, if necessary, water tightness or hermetic seal with helium without breaking the optical component.
• the assembly then requires a stop stop of the punch (not shown) embodying a predetermined setpoint for relative longitudinal movement of the ring relative to the frame, said longitudinal movement being stopped by said stopper from this setpoint value reached.
• a force sensor is not useful in this case.
• a cylindrical (glass) lens 3 mm in length and 1.25 mm in diameter (tolerance: + 5 microns / - 10 microns) was engaged in a brass frame reamed to the same diameter (tolerance: + 5 / + 15 microns); a brass ring fitted with a conical bore (2 degree taper and 3 mm outside diameter) has been engaged around the conical outer face (of the same taper) of the frame, until these faces come into mutual contact; an axial force of between 150 and 600 Newton was exerted to obtain a joining of the three parts by friction.
• the radial deformation (which in this case is an expansion measured perpendicular to the optical axis of the component) of the ring can reach 0.05 mm, which represents 1.65% of its outside diameter.
• the same lens is engaged in the same brass frame as in the previous example.
• the ring the internal face of which has a taper of 2 ° and an external diameter of 2mm, is made of stainless steel. Its radial expansion, once pressed, can reach 0.1 mm, which represents 5% of its outside diameter; this result shows that in this case also, the stresses imposed on the ring can be greater than its elasticity threshold (which when it is reached is also accompanied by a relative elongation of less than 1% or even 0.5%) .
• the use of an aluminum ring of the same geometry has given equivalent results.
• said frame may be previously covered with a metallic deposit, preferably a gold deposit.
• the frame 3 and the ring 4 are of tubular (cylindrical) shape, hollow; the cylindrical optical component 2 can slide with little play in the mount 3; after shrinking of the ring and the frame, the three parts 2, 3, 4 are definitively secured; preferably, when the frame and the ring are cylindrical, the diameters of the external face 9 of the frame and of the internal face 10 of the ring are provided to allow forced fitting of the ring around the frame, to restrict the latter and cause the simultaneous attachment of the three parts 2, 3, 4.
• the ring 4 can also be preheated until the frame 3 can be inserted therein by sliding. Said ring shrinks during cooling 'and causes the crushing of the frame jamming component 2.
• the mounting principle illustrated in FIG. 6 is an improvement of the embedding principle according to FIG. 5 applying to a device conforming to those illustrated in FIGS. 4, 7 or 8.
• the external face 9 of the mount 3 is cylindrical.
• a support 82 also cylindrical, of vertical axis and substantially coincident with the axis 1 of the optical component 2, is interposed between the mount 3 and the base 13 of the press.
• the lower planar face 17 of the mount 3 is placed on an annular face 87 of said support, the optical component, inserted by sliding in said mount resting on a stop 89 of the same support.
• the diameter of the external face 9 of the mount 3 is substantially equal to that of the external face 97 of the support 82.
• the sheath 83 is of annular shape, the diameter of its cylindrical internal face 91 being very slightly greater than that of the support 82 and of the external face 9 of the frame 3; thus, said sheath 83 slides with very little play (not shown in the figure) around the frame 3 and the support 82.
• the conical internal face 10 of the ring 4 is brought into contact with the external face 9 of the frame.
• An elastic element 84 bearing on the base 13 pushes the sheath 83 upwards against the lower flat face 92 of said ring 4; consequently, said sheath encircles the part 99 of the frame 3 situated under said lower flat face 92 of the ring.
• the frame is constantly guided longitudinally by the sheath and can therefore neither collapse nor buckle when it is joined to the optical component and the ring caused by the downward translation of the punch 15 whose lower annular face 86 is in contact with the upper face 18 of said ring.
• the optical component 2 is a thick, cylindrical lens with an optical axis 1.
• the ring 4 is provided with a frustoconical cavity and with a fine cylindrical external face 11 extended by a cylindrical collar 4a serving to increase the surface of support of the punch and optionally to fix said ring to a mechanical structure by bonding, welding or brazing.
• the mount 3, of annular shape, the external face of which is frustoconical with the same conicity as the cavity of the ring, is force fitted therein, its internal cylindrical face enclosing the lens. .
• the thick, cylindrical lens 2 of optical axis 1 is housed in the cylindrical bore 8 of the frame 3.
• the latter is provided with a fine frustoconical external face 9 extended by a collar 3a used to increase its bearing surface on the base during mounting and also to fix said frame on a structure.
• the ring 4 is of annular shape and has a frustoconical cavity of the same conicity as the external face of the frame. It is force fitted onto the frame, which encloses the lens 2.
• Figures 11 and 12 show a variant of the embodiment illustrated in Figure 9 in which the flange 4a of the cylindrical ring 4 has a square contour and adapted to the shape of a housing 4c provided in a structure 4b to which ia ring can thus be integral.
• an optical fiber collimator comprises an optical fiber end 5021 and a thick cylindrical lens 502 integral and held in a cylindrical capillary 5030 by gluing or other fixing method.
• the front part of the lens 502 is outside the capillary. It is fixed to the front of the ring 504 by shrinking said ring 504 and constricted by the frame 503.
• the ring has the shape of a tube extending at the rear by a cylindrical bore 5019 housing the capillary.
• the frame 603 which encloses the thick cylindrical lens 602 is embedded in a flared (conical) cavity of the ring 604 whose outer contour is cylindrical.
• Said flared cavity is extended at the rear by a cylindrical bore 6019 housing a ferrule 6030, also of cylindrical shape, containing one end of optical fiber 6021.
• the component is a lens 2 of spherical shape.
• the frame 3 encloses with a thin part 31 the lens 2 on a contour and extends (longitudinally) beyond this, by a thicker part 32; the frame has a flat face 33 extending in a plane 34; this plane serves as a border separating said thin 31 and thick 32 parts; it is orthogonal to axis 1; the face 33 serves as a stop and support for the lens 2. It thus makes it possible to improve the precision of the longitudinal positioning of the lens in the frame and to facilitate its mounting.
• the optical component 2 has a thin cylindrical contour. It is enclosed over its entire periphery by the thin part
• the optical component is a lens
• FIG. 17 it is a window whose faces are planar.
• An optical fiber consists of a light-conducting heart and an optical sheath.
• the optical sheath can possibly play the role of protective sheath.
• the core and the optical cladding are based on silica.
• the optical sheath is covered with a protective sheath, generally made of acrylate, itself possibly covered with a mechanical sheath (often called a "buffer").
• the mount 303 consists of a cylindrical cavity 308 partially accommodating the optical sheath 3020 of an end of optical fiber.
• the diameter of the cavity 308 is very slightly greater than that of the optical sheath 3020 so that it can slide.
• the cylindrical outer face 309 of the frame is supported on the flared inner face 3010 of the ring 304, so that once embedded in said ring, the frame encloses the optical sheath.
• the ring has the shape of a tube (ferrule) whose internal flared face (frustoconical) is extended at the rear by a cylindrical bore 3019 in which the protective sheath 3021, and possibly the "buffer" of the optical fiber (not shown), may extend partially.
• FIG. 19 represents an alternative embodiment of the invention also applied in the vicinity of the end of an optical fiber.
• the frame 403 has the shape of a tube made up of two cylindrical parts: a thin front part 409, and a rear part 4032 of larger diameter.
• the optical sheath 4020 can slide in the cylindrical bore 408 of said thin part, the diameter of which is slightly greater than that of said optical sheath.
• the optical fiber provided with its protective sheath 4021 and possibly with its "buffer”, extends partially at the level of the thick rear part 4032 of the frame in a cylindrical bore 4030 of diameter greater than that of said protective sheath or of said buffer (not shown).
• the ring 404 has a frustoconical internal face 4010 bearing on the fine cylindrical part 409 of the frame.
• said fine cylindrical face 409 of the frame is designed to shrink and jam the optical sheath 4020 of the fiber.
• FIGS. 20 and 21 represent the same variant embodiments of the invention as those illustrated respectively in FIGS. 18 and 19 applied to the optical sheath 3020/4020 of an optical fiber between two covered portions of the protective sheath 3021/4021 ( whose diameter is generally 250 ⁇ m for silica optical fibers; it may be 400 ⁇ m for certain fibers with polarization maintenance).
• the diameter of the front cylindrical bore 308/408 of the mount 303/403 is slightly greater than the diameter of the protective sheath 3021/4021, so that the optical fiber can be inserted therein up to its optical sheath 3020/4020.
• Ring 304/404 and mount 303/403 are dimensioned so that the optical sheath 3020/4020 is wedged in said mount 303/403 after embedding of said ring 304/404.
• the sheath of an optical fiber (silica-based) with a diameter of 0.125 mm +/- 0.5 microns was engaged in a brass frame bored to the same diameter (tolerance + 5 / + 11 microns ); a brass ring fitted with a conical hole (1.5 taper and 2.4 mm outside diameter) was engaged around the cylindrical external face of the frame (1 mm outside diameter); an axial force was exerted between 50 and 400 Newton to obtain a joining of the three parts by friction.
• the optical component has a sufficient length, and in order to avoid excessive tightening over the entire length of the frame which may generate undesirable modifications of its optical characteristics, it is possible to interpose 2 thin and narrow deformable rings 40 (FIG. 23), or even a single thin and narrow ring 40 (FIG. 24), or even a thin and narrow ring 40 as well as a narrow annular projection 41 (FIG. 25) integrated into the frame 3, between the frame and the component 2 .
• FIGS. 26 to 28 illustrate an alternative embodiment according to the invention in which the frame 203 comprises a thin part 2031 provided with a cavity of rectangular shape 208 of rectangular base, whose height and width are slightly greater than those of the optical component 202 , also a rectangular base with a rectangular base which it receives.
• the external faces 209 of the frame 203 and internal 210 of the ring 204 are frustoconical with similar cone angles.
• the frame 203 extends (longitudinally) beyond its thin part 2031, by a thicker part 2032 whose plane border 2033 with the thin part 2031 serves as a stop and support for the optical component 202, thus making it possible to improve the positioning accuracy of the component in the frame and facilitate its mounting.
• the frame Once the frame is forcibly embedded in the ring, it encloses the component on its periphery by constriction of its cavity 208.
• Figure 29 is a section in a transverse plane (perpendicular to the axis of revolution of the frame or the ring). It illustrates an alternative embodiment of the invention in which the optical component 102 is of rectangular parallelepipedal shape and the cavity 108 of the frame 103 is cylindrical with a circular outline. The diameter (before mounting) of said cavity 108 is slightly greater than the diagonal (along a transverse plane) of the optical component 102. Said cavity shrinks during mounting under the action of the ring 104 to grip said optical component at its corners. This configuration is advantageous when sealing with helium or sealing with water is not required since a cylindrical bore of circular outline is generally simpler to manufacture than a parallelipiped bore. However, the non-uniform radial stress imposed on the component can generate birefringence if it is too great. Said constraint must therefore be checked.
• Figures 30 to 35 show two embodiments of the invention in which the frame consists of two distinct elements.
• semi cylindrical means having the form of a half cylinder cut along a plane passing through its axis.
• the two elements 103a and 1103b forming the frame are identical. They consist of a thin external face 11031a and 11031 b of semi-cylindrical shape extending forwards by a flange also of semi-cylindrical shape 11032a and 11032b, of a contact face 11035a and 11035b allowing the support of the two elements one on the other over their entire length, and a semi-cylindrical groove 1108a and 1108b constituting a half cavity;
• the mentioned semi-cylinders are coaxial.
• a tool 1 160 is provided with a cylindrical cavity 1161 of diameter very slightly less than the diameter of the flanges 11032a and 11032b, the coefficient of expansion of which is greater than that of the two elements and the material of which is also substantially more ductile.
• the tool is heated until its diameter becomes greater than that of the flanges of the two elements.
• the elements 1103a and 1103b are joined, bearing on their contact faces 11035a and 11035b then introduced into the cavity 1161 until the stop 1162.
• the tool 1160 After the tool 1160 has cooled, the latter encloses the two parts 1103a and 1103b which are then integral and supported on their contact face 11035a and 11035b.
• the diameter of the frame cavity (for a frame in one piece), must be much greater than that of the component. This is for example the case for a piece of optical fiber equipped with a connector at one end and a capillary at the other end. If the frame was in one piece, the diameter of its cavity should be greater than that of the capillary or connector for threading the optical fiber. The uniform shrinkage of the frame would then become delicate, even impossible without its rupture and / or its random deformation, until the optical fiber is tightened.
• the grooves 1208a and 1208b of the two elements 1203a and 1203b are half rectangular parallelepipeds (cut along a plane parallel to one of their faces) and are designed to receive the parallelepiped component 1202 (filter, insulator, windows , lens or mirror).
• the external faces 1209a and 1209b of the two elements 1203a and 1203b are semi-cylindrical. Once supported on their respective contact faces 12035a and 12035b, they are partially introduced into the cavity 1261 of the tool 1260.
• the ring 1204 of frustoconical internal face 12010 is supported on the cylindrical external face of the two elements joined apart of the tool, so as to cause the cavity formed by the two grooves 1219a and 1219b to shrink around the component 1202.
• This alternative is advantageous when the component has a rectangular shape and it is difficult to make a cavity in the frame that matches its shape.
• Figures 36 and 37 show a type of embodiment of the invention in which the frame 1303 has three holes drilled, each narrow part 1308a, 1308b, 1308c of cylindrical shape, houses the optical sheath 13020a, 13020b, 13020c of an optical fiber and is extended at the rear by a wide part 13019a (not shown), 13019b, 13019c (not shown), also of cylindrical shape, housing the protective sheath 13021a (not shown), 13021 b, 13021c (not shown) of said optical fiber.
• Internal face of the ring 1304 and external face of the frame 1303 are of frustoconical shape, substantially of the same cone angle, so that once the frame is forcibly embedded in the ring, each narrow part 1308a, 1308b, 1308c of each lamé hole shrinks to wedge each of the optical sheaths 13020a, 13020b, 13020c.
• a portion of structure 704 in the form of a thick wall constitutes three respective hooping rings of three mounts 703a, 703b, 703c for fixing the optical sheath 720a, 720b, 720c of 3 parallel optical fibers between they.
• the last two embodiments according to the invention are not limited to
• optical fibers and can be applied to other components. They are useful for attaching, for example, layers of optical fibers or lens arrays to a wavelength multiplexer, "switch” or other system requiring the arrival and / or exit of several "channels »Optical.
• Figures 39 and 40 illustrate two examples of use of the invention to make integral and to align a lens and an end of optical fiber.
• the function of each device illustrated in these figures may for example focus the beam from the optical fiber on a detector by means of the lens, or collimate the beam from the fiber.
• the optical fiber 802 and the lens 902 must be positioned longitudinally (along the axis 1) and aligned transversely to properly fulfill their function.
• the frame 903 secured to the lens 902 and the ferrule 25 (containing the fiber 802) are in abutment against two shoulders 9040 and 9041 defining the longitudinal distance between the two optical components.
• the mechanical elements used mounts and rings have concentricities between their internal and external faces, which are sufficient to allow correct transverse alignment of the components 802 and 902.
• the fiber 802 is held in the ferrule 25 by a conical mount crimped according to
• the lens 902 is mounted in abutment against an annular portion of the frame 903 forming an internal projection at the bore thereof.
• the frame 903 (the outside of which is conical) is deformed by force insertion into the ring 904 with a conical bore.
• the dimensions and tolerances of the elements 902, 903, 904 mean that when the frame 903 comes against the shoulder 9040, it is sufficiently deformed to hold the lens 902.
• an additional conical mount 9030 is provided between the ferrule 25 and the ring 904.
• Said mount 9030 is embedded in the ring 904, once the ferrule 25 abuts against the shoulder 9041, until it holds the ferrule.
• Another technique illustrated in FIG. 40 can be used to ensure precise longitudinal spacing of the fiber 802 and of the lens 1002, for example, when the positioning tolerance of the stops 10040 and 10041 of the ring 1004 is not sufficient.
• the ferrule 25 is inserted into the main ring 1004, then a second conical ring 1104 is enshrined on the main ring 1004 until the ferrule 25 can slide without play in the bore 10042 of the main ring .
• the position of the ferrule is then adjusted to the optimal position.
• the conical ring 1104 is then more vigorously embedded so as to block the fever 25 in its optimal position.
• the slack without play means that there is no relative movement of the ferrule 25 relative to the lens 1002 when it is locked; these techniques make it possible to obtain the desired spacing between the components 802, 1002 with an accuracy of a few microns.
• a first annular part 10043 at the end of the part 1004 forms a clamping ring for the mount 1003, while a second annular part 10044 at the end of the part 1004 forms a deformable mount for fixing the ferrule 25 under the pressure exerted by the additional ring 1104.
• the arrangements according to the invention can be used for the production of an optical device 32 comprising, inside a sealed housing 26, 27, a laser diode 28, a collimating lens 29 of the beam produced by the diode, an insulator 30, and a focusing lens 31; a ferrule 25 in which an optical fiber 802 extends, extends through an orifice provided in the wall 26 of the housing.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Couplings Of Light Guides (AREA)
• Lens Barrels (AREA)

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• 2001
  • 2001-02-09 FR FR0101804A patent/FR2820790B1/fr not_active Expired - Fee Related
  • 2001-12-26 US US10/250,515 patent/US20040052476A1/en not_active Abandoned
  • 2001-12-26 EP EP01989662A patent/EP1356330A1/de not_active Withdrawn
  • 2001-12-26 WO PCT/FR2001/004201 patent/WO2002054128A1/fr not_active Application Discontinuation

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