Optical wave guide with marking and method for producing said optical wave guide

p0001description

p0002Light waveguide with a marker and method for producing such an optical waveguide

p0003The present invention relates to an optical waveguide, which is provided with a continuous coating and having at least one defined marker, and a method for manufacturing such a fiber-optic cables ester.

p0004An optical waveguide of this type is. Known from US 5,379,363. Therein is shown an optical fiber, which is superficially provided with annular markings. The optical waveguides and the ring markings are also provided with a top layer of UV-curable varnish. The annular color markings can have a thickness of several micrometers.

p0005Each of the color marks forms an application layer at local sites along the length of the optical waveguide, which projects radially with respect to the other, the circular-cylindrical outer circumference of the optical waveguide to the outside. The markings emitted subsequently to the optical waveguide dyes act as inhomogeneities. In particular, they may cause local material stresses and therefore microbending of the optical fiber contained in the fiber, so that undesirable transmission losses can occur due to microbending.

p0006The object of the present invention is to provide a light waveguide of the aforementioned type, in which microbending losses due to marks on the optical waveguide largely avoided. In addition, it is an object of the present invention to provide a method for manufacturing such optical waveguide.

p0007The object relating to the optical waveguide is achieved by an optical waveguide according to claim 1. The object regarding the method is achieved by a process for producing a provided with a defined marker light waveguide according to claim. 5

p0008The marking of the fiber according to the invention is effected rials in the form of a partial color change of Beschichtungsmate- of a color different from that adjacent to the marker remaining coating material. Accordingly, the marks are not formed by a respective application layer in the invention, which are applied to the optical waveguide subsequently, so that no inhomogeneities due to such applied color markings may arise. This effectively prevents it comes to lo- cal material stresses and thus to microbending losses of an optical fiber included in the optical waveguide.

p0009The coating material is an iron salt of an aliphatic hydrocarbon acid and gallic acid is added to form the coating or a so-called Coatings or cable sheath of the light waveguide. The film coated with the coating optical waveguide is then at least partially heated superficially, so that the partial color change for producing position of the mark is effected at the heated part of the optical waveguide. In a preferred

p0010Embodiment, the coating material rat a Eisenstea- and added gallic acid. After heating above the melting point of Eisensstearats, the iron ions react with the gallic acid, which occurs in particular a black color of the coating aterials. The required heating can advantageously be effected by energy radiation, in particular by means of a laser beam. The requisite heating may also be effected by means of a partially heated guide roller over which the optical waveguide is guided or drawn off in the production process.

p0011Opposite optical waveguides with radially outwardly projecting color coding layers can be guaranteed to solvents with the invention, a higher abrasion resistance of each marker or resistance. Since no additional material orders are necessary, the coating or the coating of the optical fiber in a single operation as a continuous smooth, uniform outer diameter containing coating can be formed. By a uniform diameter of the optical waveguide problems in the further processing, for example during a subsequent stranding, or problems with respect to the optical properties of the optical fiber effectively be avoided. When optical waveguide according to the invention, the markings may be removed during further processing, for example in the stranding, not. In particular, an abrasion or damage of the markings is no longer possible. Besides such mechanical advan- tages arise optical benefits, in the form of avoidance of additional losses due to changes in diameter of the optical waveguide by color marking jobs.

p0012Further advantageous embodiments and developments of the invention are specified in dependent claims.

p0013The invention is explained below with reference to figures illustrated in the drawing. Show it

p00141 shows a first embodiment for carrying out a method according to the invention, Figure 2 shows another embodiment for carrying out the process.

p00151 shows an optical waveguide LW is shown, which is to the right, moving within the manufacturing process of the left. The optical waveguide LW has at least one of the light guide serving optical fiber LF, which is provided by the coating device CD with a coating or a coating CT or with a fiber color. The loading stratification can be formed on or multilayered, in the latter case is an inner layer to protect against microbending and an outer layer of simpler handling and can be used for identification. The optical fiber LF is shown symbolically and for example, a single fiber, a fiber ribbon or fiber bundle representing multiple fibers.

p0016The coater CD is also shown only symbolically, fed the coating material BM. The coating material is in particular an iron salt of an aliphatic hydrocarbon acid and gallic acid added so that distribute the substances homogeneously. In a preferred embodiment the iron stearate coating material (iron salt of stearic acid) and gallic acid (generally as known C7H605) is added. It can also be used iron salts of other aliphatic hydrocarbon acids, in particular, by the proper selection of the melting point can be set varies and defined and, where appropriate, the hue can be varied. When using iron stearate, the melting point is about 80 to 100 ° C. Below the melting point go the iron stearate and the gallic acid is a chemical bond. After heating to above the melting point of the Eisenstearats addition, the iron ions react with the gallic acid, whereby a black color change in the CT Coatings produced. In the example of Figure 1, the markers Ml and M2 are obtained by local heating at least the surface of the optical waveguide LW, wherein the respective heated areas of the optical waveguide, a partial color change of the coating material for the production of the respective mark is effected. The heating is effected by means of a heated deflecting roller UR2 partially over which the light waveguide LW, in this example, after passing the pinch roller UR1, guided. Even after each color change the surface of the optical waveguide LW is further adapted to be smooth and has a uniform outer diameter. This has the advantage that the marks Ml and M2, for example, as part of a stranding or the like can not be removed again opposite outwardly projecting subsequently applied labels. Furthermore, additional losses are avoided as a result of changes in the diameter of the optical waveguide.

p00172 shows a modification of the embodiment according to

p0018Figure 1 shown. In the embodiment of Figure 2 is a heating of the coated optical waveguide LW or a heating the surface by energetic radiation ST, in particular by means of a laser beam of a laser LA is effected. Thus, the melting point of the admixed Eisenstearats is locally exceeded, whereby the iron ions react locally with the gallic acid. This creates the defined marks Ml and M2 that of the adjacent to the markings remaining coating material colorless borrowed stand. The optical waveguide so marked LW is drawn from a deduction AZ.

p0019It is also the arrangement of several partially heated pulleys or laser emitter or the combination of a laser with a mirror system conceivable to heat a larger peripheral area of ​​the optical waveguide. There- by this must not be heated more than its entire cross section.