Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – With measuring – controlling – sensing – programming – timing,...
Reexamination Certificate
1997-10-21
2001-05-15
Hoffmann, John (Department: 1731)
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
With measuring, controlling, sensing, programming, timing,...
C065S378000, C065S407000
Reexamination Certificate
active
06230522
ABSTRACT:
In practice, the optimum setting of welding or, respectively, splicing parameters, which include for example, pre-welding current or, respectively, temperature, pre-welding duration, longitudinal spacing of the fiber ends during the pre-welding, fiber feed, main welding current intensity, main welding duration, electrode spacing, etc., can be made difficult for the faultless thermal welding, particularly fusion welding of light waveguides. Additionally, the mutual dependencies or, respectively, inter-dependencies of the parameters on one another are thereby unfavorable for the setting.
The fusion welding method of U.S. Pat. No. 4,948,412 attempts to keep the influence of concentricity errors of the cores of two optical fibers to be welded to one another on the splice attenuation of their finished welded connection as low as possible. To that end, the two optical fibers are first aligned in alignment with one another with respect to their eccentric fiber cores and the lateral misalignment, i.e. offset, between their central axes that results therefrom is then measured, for example with the assistance of a microscope. For the subsequent fusing of the glass material of the two optical fibers, the welding time, the welding current or the welding energy are determined according to an inverse relationship to this measured, original, i.e. initial offset. One thus prevents the self-centering of the fibers relative to one another from becoming too great due to the surface tension of the molten glass material of the fibers and prevents the fiber cores previously aligned in alignment with one another from being inadmissibly offset relative to one another or, respectively, bent. Such a determination is thereby implemented for the production of every individual fiber splice and this makes the method very involved. A further disadvantage of this known method is that the fiber core eccentricity by itself does not represent the critical quantity for achieving an optimum welding process, i.e. this method only incorporates the possible quantities that define a quality of the welded connection to an inadequate extent.
EP-A1 0 504 519 discloses a light waveguide welding means wherein a pressure sensor is provided that generates a control signal dependent on the measured atmospheric air pressure. The respectively applied discharge current is set to a predetermined value on the basis of the air pressure measured in this way. In addition to the not inconsiderable outlay for the pressure cell as well as for the control quantity to be derived therefrom, this method likewise has the particular disadvantage that the air pressure by itself does not represent the critical quantity for achieving an optimum welding process.
WO 95/24664 discloses a method for welding the ends of optical fibers wherein the manipulated variables for the arc are selected such that the electrical power is kept constant during the welding process itself. To this end, a voltage is generated that is proportional to the respectively momentary power, and this voltage is forwarded to a control means that varies an electrical actuator such that the power is respectively kept essentially constant during the welding process (specifically, during the arc drop voltage). This method likewise incorporates the possible quantities that determine a quality of the welded connection to an inadequate extent.
SUMMARY OF THE INVENTION
The invention is based on the object of disclosing a way of how welding parameters for the thermal welding of waveguide fibers or, respectively, optical fibers can be set better under a number of practical conditions.
This object is inventively achieved in the following way:
Method for setting welding parameters for the production of a thermal weld between two respective optical fibers, comprises the steps of
positioning at least two optical test fibers relative to one another with a prescribable, radial initial offset,
contacting the end faces of these test fibers, which are arranged radially offset relative to one another, with one another,
heating the region around the contacting point of the test fibers so that in at least one welding process an offset-reducing effect between the two test fibers occurs,
and utilizing the resultant reduction of the initial offset for setting at least one welding parameter.
This makes it possible to simply as well as reliably adapt at least one of the welding parameters such as, for example, intensity of welding current, welding duration, etc., which parameters are critical for the respective welding process, to the welding conditions respectively currently present (such as, for example, air pressure, air humidity, air temperature, type of optical fiber employed, electrode condition, etc., under a number of practical conditions. Possible quantities determining a quality of the weld can thus be comprehensively co-involved. Changing or, respectively, different welding conditions can thus be taken into account, i.e. the setting of welding parameters can thus be undertaken in a simple way such that an optimally good weld between two respective optical fibers that is largely independent of environmental and/or ambient influences can be produced. The splice quality of thermal welds between at least two optical fibers can be quite substantially improved in this way.
The invention is also directed to a method for the welding of respectively two optical fibers allocated to one another,
whereby at least one test splice for determining an optimum set of welding parameters is first produced in at least one pre-trial for the respectively currently existing welding conditions. The method comprises testing by arranging two test fibers offset relative to one; another with a prescribable, lateral initial offset with respect to their long sides, by bringings these test fibers arranged laterally offset relative to one another into contact with one another at their end faces, by heating the contacting region of these two test fibers so that, due to the surface tension of their melted glass material, the predetermined lateral initial offset is reduced, and by identifying at least one criterion for this offset reduction;
determining the optimum set of welding parameters on the basis of the at least one criterion and setting the welding parameter in fixed fashion for the existing welding conditions;
and only after this at least one pre-trial then producing the actual weld between two respective optical fibers with the optimum welding parameters determined therefrom.
The invention is also directed to an apparatus for setting welding parameters for producing a thermal weld between at least two optical fibers, which apparatus includes, positioning means with which at least two test fibers can be positioned with a prescribable radial initial offset relative to one another are provided, a heating device is provided that heats the region around the contacting location of the test fibers such that an offset-reducing effect can be effected thereat, and an evaluation/control means is provided that acquires the effected reduction of the initial offset and utilizes it for setting at least one welding parameter.
Other advantages and features of the invention will be readily apparent from the following description of the preferred embodiments, the drawings and claims.
REFERENCES:
patent: 3819249 (1974-06-01), Borner
patent: 4557556 (1985-12-01), Decker
patent: 4557557 (1985-12-01), Gleason
patent: 4948412 (1990-08-01), Yamada et al.
patent: 5011259 (1991-04-01), Lieber et al.
patent: 5013345 (1991-05-01), Itoh
patent: 5046812 (1991-09-01), Yanagi
patent: 5078489 (1992-01-01), Lieber
patent: 5249247 (1993-09-01), Whitesmith
patent: 5648007 (1997-07-01), Reslinger
patent: 321947 (1989-06-01), None
patent: 0 504 519 (1992-09-01), None
IEEE, Aug. 1978, Hatakeyama et al. “Fusion Splices for Single-Mode Optical Fibers” pp. 614-619.*
ECL Tech. Journ. (1979) Hatakeama et al, Fusion Splices for Single-Mode Optical Fibers pp. 981-997.
Hoffmann John
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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