Patent Application
20090238524
The disclosure relates to an apparatus for thermal connection of at least two optical fibers. The disclosure also relates to a method for thermal connection of respective ends of at least two optical fibers.
Apparatuses for connection of optical fibers by means of heat influence are referred to as splicers. In splicers, the fiber ends of the optical fibers to be connected are heated, as a result of which they are fused to one another. The fusion process is also referred to as splicing. Different attenuations can occur within the connection, depending on the position of the two optical fibers with respect to one another and further parameters such as the splicing temperature or splicing time that is used. It is, of course, desirable for the resultant attenuation after a splicing process to be as low as possible, in order to avoid unnecessarily reducing the signal quality.
In order to improve the quality of a spliced connection such as this, it is known for the ends of the optical fibers to be spliced to be aligned accurately with respect to one another. By way of example, an arc, a corona discharge, a laser beam or some other form of a heat source is then used to melt the fiber ends before joining them together.
Electromechanical motors or piezoelectric elements, inter alia, can be used for the alignment or positioning of the two fiber ends with respect to one another. Each of the respectively used positioning types has its own positioning accuracy. For example, stepping motors and the associated step-down conversion are available at low cost, but the positioning accuracy of this mechanism is less than that of piezoelectric elements.
Splicers have recently been required which can be produced at low cost and are intended to be as reliable as possible during use, simple to operate, and to require little maintenance. The splicers are generally designed to be portable and are frequently used for installation of optical fibers in buildings. Portable splicers frequently have no complex and accurate positioning mechanism, for cost reasons. Other splicers, for example as known from U.S. Pat. No. 6,230,522, use a complex recording and alignment electronics in order to ensure that the optical fibers are aligned as accurately and reproducibly as possible with respect to one another at the start of a splicing process. To this end, the actual splicing process is then carried out using a fixed splicing current, and for a fixed splicing time.
Irrespective of the splicer that is used, the increasingly stringent requirements for signal quality make it necessary to further reduce the attenuation caused by the splicing process between different optical fibers. It is therefore desirable to provide an apparatus of the type mentioned initially, by means of which the quality of a thermal connection of two optical fibers can be improved further. At the same time, it should still be possible to operate the apparatus easily. A further aim is provide a method which offers a better splice quality.
One embodiment of the present application provides for two positioning units to be provided in an apparatus for thermal connection of at least two optical fibers, with one optical fiber being associated with each of these positioning units. The positioning units are designed such that the ends of the two optical fibers can be moved relative to one another to a position which allows thermal connection. A device having a first component and a second component is provided for the heating which is required for the thermal connection of the ends of the first and second optical fibers. The two components are arranged along one axis.
In order to improve the quality of a thermal connection of the two optical fibers, an observation device is provided, by means of which the distance of the end of at least one of the at least two optical fibers from at least one of the components of the device for heating can be determined. Alternatively, it is possible to determine the distance from the axis along which the components of the device are arranged. The observation device is coupled to a control apparatus, which is designed for adjustment of at least one control parameter for the device for thermal connection, as a function of the distance.
The position of the ends of the two fibers relative to a heat source is recorded for the process of thermal connection. This allows the distance of the two ends of the optical fibers from the heating source to be determined accurately. The distance is taken into account in the adjustment of control parameters which are important for the splicing process. Furthermore, it is possible to use the existing positioning units together with the observation device to additionally determine the two ends of the optical fibers relative to one another. This further improves the quality of the spliced connection.
In one embodiment, a memory is provided in the control device, in which memory values are stored which represent a predetermined relationship between a possible distance and the at least one control parameter. Alternatively, the control apparatus or the memory may have an appropriate calculation rule which provides a relationship between values of possible distances and the at least one control parameter. This makes it possible to select from a multiplicity of possible settings of a control parameter those parameters which are optimum for the respective distance. Further control parameters may now be selected, by means of which the heat source is then operated for the actual process of connecting the two optical fibers. Alternatively, when an already known calculation rule is used, it is possible to determine the optimum value of one or more control parameters directly from the determined distance.
In one embodiment, the at least one control parameter is linked, for example, to a supply current of the heat source or to an amount of heat produced by the heat source. It is likewise possible to adjust the time duration during which the fiber ends are heated, as a function of the determined distance. In addition, different temperature ranges can be selected as a function of the determined distance for the process of connecting the fiber ends. Further options are to adjust a pre-splicing current for the heating of the fiber ends, and/or the time duration for heating of the fiber ends, before the actual connection process, with the aid of the at least one control parameter.
In one embodiment, the positioning units can be fixed in position with respect to one another by evaluation of the distance of the two optical fibers from the heat source or from an axis along which the heat source or components of the heat source is or are arranged. The proposed apparatus can therefore also be used in simple appliances without complicated positioning elements.
In another embodiment, the heat source comprises a pair of electrodes which are arranged along the axis. In another embodiment, again, the heat source contains a laser device which produces a laser light beam along the axis. It is likewise possible for a resistance wire or heating wire to be provided as the heat source. This is arranged along the axis.
In another embodiment, a heat source is provided which has two components arranged along one axis. The two optical fibers to be connected are positioned relative to one another such that they can be connected by heat influence with the aid of the heat source. An image of the ends of the at least two optical fibers with respect to the axis is then recorded. This image is used to determine the distance of at least one end of the two optical fibers from the axis. A value is produced from this, which indicates a dependency between a possible distance and a control parameter which influences the heat produced by the heat source. The heat source is then operated as a function of the control parameter, in order to connect the ends of the at least two optical fibers to one another. The splicing process is controlled individually for each connection by operating the heat source with the aid of the control parameter from the determined distance. By way of example, this makes it possible to correct the different positions of the optical fibers with respect to the axis, thus producing a splice result which is independent of the distance.
The concepts will be explained in more detail in the following text with reference to a plurality of exemplary embodiments which are illustrated in the drawings. Components which have the same effect or the same function are provided with the same reference symbols in the various figures.
A heat source having the two components 40 and 41 is provided in order to produce the heat required for thermal connection of the two ends of the optical fibers 10 and 11. The two components 40, 41 represent electrodes whose electrode tips are arranged specifically with respect to one another along an axis 43. The two optical fibers 10, 11 are positioned between them and essentially at right angles to the axis. The electrodes are connected to an electrical power source 91 in order to operate the two electrodes 40, 41 and to supply them with the supply current which is required for production of an arc.
According to the embodiment shown in
The images produced by the cameras 50 and 60 are passed on to the microprocessor 63, where they are evaluated. The microprocessor sets the position of the optical fibers 10, 11 in conjunction with the position of the fixed-mounted cameras. The position of the fibers 10, 11 relative to one another and the distance of the two fibers from the axis 43 of the heat source can be determined accurately, taking account of the recording parameters of the position image.
During operation of the splicer, the positioning of the fibers 11, 10 with respect to one another, for example, is recorded for the splicing process such that the relative offset is reduced as much as possible. The fiber 10 is then moved along the z-direction, such that both fiber ends are now arranged symmetrically about the axis 43 of the heat source.
The distance of the fiber ends from the axis 43 is determined in order to improve the actual splicing process and therefore to reduce the attenuation losses after the two fiber ends have been connected. The microprocessor 63 passes this distance to a control apparatus 82 in which, in the present embodiment, a calculation rule is stored. The control apparatus 82 uses the calculation rule to produce a plurality of control parameters, in order to control the splicing process as a function of the determined distance of the two fiber ends from the axis 43. By way of example, these control parameters include the time duration for a pre-splicing current in the two electrodes 40 and 41 for heating of the two optical fiber ends. Before being melted, the ends are heated for a certain time with the aid of the pre-splicing current, and are therefore prepared for the splicing process.
This makes it possible to take account of greater or lesser distances of the two fiber ends from the axis 43 during the heating of the two fiber ends which precedes the actual splicing process. Furthermore, the amount of heat and the splicing time for the splicing process that is then carried out are controlled as a function of the distance of the two fiber ends from the axis 43. In addition, the offset of the two fiber ends, which is recorded by the cameras and is evaluated in the microprocessor 63, with respect to one another is taken into account for the splicing process.
In the present embodiment, the positioning units 30 and 31, and therefore the grooves 32, are arranged in exact positions with respect to one another. The positioning accuracy of the optical fibers 11, 10 which have been placed in the grooves is governed directly by the position of the fibers 10, 11 in the grooves 32. The position of the optical fibers 10 and 11 can be changed manually.
In this case, the optical fibers are in the form of glass fibers with one or more light-carrying cores. Those ends of the optical fibers which are arranged in the splicing area originate from an optical waveguide 200. The latter in each case comprises its jacket 100 or 110, which is at a distance from the optical fibers 10 or 11, outside the splicing area. The actual glass fiber is therefore exposed in the splicing area. All known types of optical waveguides are suitable as optical fibers, but in particular single-mode fibers or NZD fibers (non-zero-dispersion-shifted fibers).
The optical fiber 10 can be moved along its z-direction with the aid of a sliding table 34, which likewise has a V-shaped groove. In addition, cameras 50 and 60 are arranged in the x-direction and z-direction, respectively. Lighting elements 51 and 61 are used for illumination, are associated with the imaging cameras 50 and 60 and illuminate the splicing zone 42.
During operation, once the two optical fibers 10 and 11 have been fixed and positioned in the grooves 32 in the positioning units, the two cameras 50 and 62 produce a respective position image 52 and 62. The two position images, which are supplied to a microprocessor 80 for further evaluation, can be used to determine the distance of the end of the optical fiber 11 from the two tips of the electrodes 40 and 41. For a uniform splicing process of both ends, the position of the optical fibers 10 is now changed in the z-direction with the aid of the positioning unit 34. The ends of the two optical fibers are arranged as far as possible at the same distance around the tips of the two electrodes 40 and 41 and at the same distance from the electrode tips. This results in the two fiber ends being heated uniformly.
Control parameters are selected from the memory 81 in the microprocessor 80, as a function of the determined distance of the two fiber ends from the axis of the electrode tips. The pre-splicing current, the pre-splicing time duration, the splicing current or the time duration for the splicing process are now set for the subsequent splicing process with the aid of the control parameters. The splicing parameters are therefore controlled as a function of the distance of the fiber ends from the tips of the splicing electrodes, thus resulting in a splicing result which is independent of this distance.
There are several possible ways to determine the distance of the respective glass fibers or optical fibers from the heat source.
The optical fiber 11, with its core 12, is arranged in a groove, which is not illustrated, in a positioning element, at a fixed distance d from the heating wire 43a. The cameras record an image of the position of the end of the optical fiber 11 from the tips 44 of the two electrodes and from the heating wire 43a. The distance d can be deduced from the recorded images. The optical fiber 10 is then moved along its z-direction until its distance d′ from the heating wire 43a corresponds to the distance d. The two ends of the optical fibers 10 and 11 are arranged at the end of the positioning process at the same distance around the wire 43a. The appropriate control parameters for the subsequent splicing process are calculated as a function of the distance d, and the thermal connection is thus produced.
By way of example, it may be expedient to provide a greater splicing current or longer splicing times if the distances are relatively great. Pre-splicing currents and/or pre-splicing times may also possibly be changed. In one alternative embodiment, for example, a pre-splicing time can also be used to determine the distance d and d′ of the optical fibers from the wire 43a. It is therefore possible to determine control parameters, by means of which the subsequent splicing process will be controlled, during the time period in which the two optical fibers are heated.
In another embodiment, a laser beam is provided as the heat source. In this embodiment, the laser beam can be activated with as low an intensity as possible prior to the splicing process, for positioning and determining the distance of the two fiber ends from the laser beam. The image of the laser beam and the ends of the two optical waveguides with respect to one another can be recorded with the aid of a camera with accurate positioning thus being carried out.
Finally,
A decision is then made in step S3 as to whether the position of the fiber ends with respect to one another is below a predetermined threshold value. If this is not the case, a readjustment process must therefore be carried out, and the method is continued with a further iteration in step S1. If, in contrast, the predetermined limit value is undershot in step S3, the positioning of the fiber ends with respect to one another has been completed. The rest of the splicing process can then be continued in step S4.
There, another image of the fiber ends is now recorded with respect to an axis associated with the heat source. The distance of the two fiber ends from the heat source is determined with the aid of these records.
The determined distance is made to coincide in step S5 with control parameters which are used for the subsequent splicing process. The splicing time or else the heat developed by the heat source is controlled with the aid of the control parameters. The process is then carried out in step S6, as a function of the distance and the positioning of the fibers with respect to one another.
The recording of another image in step S4 after positioning of the fiber ends with respect to one another may also be omitted if the recording of an image of the fiber ends in step S2 likewise includes the recording of the image of the fiber ends with respect to an axis which is associated with the heat source. The most recently recorded image of the splicing area before completion of the positioning steps is then used to determine the distance. In step S5, the control parameters are determined from the distance that has been determined in this way.
It is likewise possible, at least in some cases, to carry out the individual method steps during a pre-splicing process. In particular, it is possible to record an image of the fiber ends during a pre-splicing process in step S4. When an arc is produced or a laser beam is used during the pre-splicing process, the distance between the axis associated with the heat source and the fiber ends can thus be determined from the light intensity distribution and the fiber ends. An image can also be recorded particularly easily when using a heating wire as the heat source.
The arrangement and the corresponding method allow uniform heating of the two fiber ends in the heating source. This is achieved by using a camera system in a splicing system, by means of which camera system the position of the fiber ends of the optical fibers relative to the heating source can be recorded. The image recorded by the observation device is then evaluated. Splicing parameters such as the splicing current, the time during which the fibers are heated or else different temperature levels which are passed through during the splicing process can then be set as a function of the actual position of the fiber ends with respect to the heating source. These splicing parameters can be stored as a parameter matrix in a memory. It is likewise possible to determine these splicing parameters from a known relationship rule, taking account of the determined distance. The splicing procedure is therefore not carried out with constant splicing parameters, but with the splicing parameters being adapted as a function of the actually determined position of the fibers with respect to the heating source. The position of the fiber ends with respect to the heating source can advantageously be measured by means of electrodes within the recorded image, an auxiliary void, an averaged intensity distribution of an arc, or of a laser beam, by means of the camera image.
Many modifications and other embodiments of the present invention, within the scope of the appended claims, will become apparent to the skilled artisan. Therefore, it is to be understood that the invention is not limited to the specific embodiments disclosed herein and that modifications and other embodiments may be made within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102006056398.0 | Nov 2006 | DE | national |
This application is a continuation of International Application No. PCT/EP2007/062347, filed Nov. 14, 2007, which claims priority to German Application No. 102006056398.0, filed Nov. 29, 2006, both applications being incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2007/062347 | Nov 2007 | US |
| Child | 12473612 | US |
