Patent
1982-05-10
1985-05-28
Sikes, William L.
350 9610, 350 9621, G02B 514, G02B 726
Patent
active
045196729
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a connector for an optical fibre, which connector is provided with an axial through-hole for the optical fibre and with a bushing for concentric fixing of the fibre within the connector. The bushing is arranged to be compressed in its axial direction by means of a tool in order to obtain a radial deformation resulting in a centering of the optical fibre within the connector.
BACKGROUND OF THE INVENTION
Optical connectors are known in several embodiments, for instance as described in British Pat. No. 1 478 135 and in U.S. Pat. No. 4,190,317. In the connector described in the British Patent the bushing is positioned at a considerable distance inside the mouth of the connector and is compressed axially in order to be expanded radially by means of a piston fixed within the connector by varnish, while the end of the optical fibre is, after the compression of the bushing resulting in the concentric fastening of the fibre, fixed by means of resin in the mouth of the connector. Besides being a relatively complicated construction accuracy is necessarily lost as a result of the spacing of the bushing from the mouth of the connector so that in all probability desired low optical damping can not be achieved. Errors in accuracy are also produced by the method described in said British patent since the free end will wobble during the turning of the surface, so that a different thickness of material is obtained in the bushing. The connector assembly described in said U.S. patent is also a relatively complicated construction. The bushing is tapered in order to hold the fibre after a forced insertion of the bushing into a narrow bore, which according to the preferred embodiment is made in a second bushing arranged in a recess in the mouth of the connector. Due to several details cumulative errors in accuracy are produced resulting in a deteriorated optical damping. During the force insertion of the tapered body there is also a risk of skew setting or "swelling" which also results in deteriorated accuracy.
SUMMARY OF THE INVENTION
The present invention is based on the realization that the concenctric fastening of an optical fibre requires for the decisive optical damping in the connector an accuracy in the order of magnitude of a few micrometers. The fastening should accordingly take place immediately at the mouth of the connector. Moreover, as few means as possible enclosing the fibre should be utilized and the bushing should be made of a non-elastic material in order to keep as close tolerances as possible upon the manufacture of the bore for the fibre. The invention provides an improvement in optical damping compared with previous techniques, and involves a simplified method for obtaining the concentric holding of the optical fibre in the connector. This is achieved by the following steps: of a non-elastic ductile material e.g. a soft metallic material, into a cylindrical recess in the front end of a connector; expand the rod outwardly in radial direction thereby fixing the rod in position relative to the inner wall of the recess; the outer surface of the connector; expand the rod inwardly in radial direction so as to reduce the size of the hole in the rod, thereby obtaining an accurate concentric fastening of the optical fibre.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-3 illustrate schematically different steps for manufacturing an optical fibre connector according to the invention.
FIGS. 4 and 5 show a coupling device for two connectors along the section line IV--IV in FIG. 5 and along the section line V--V in FIG. 4, respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The connector 1 shown in FIG. 1 has an axial bore 2 for an optical fibre 3. The bore is enlarged at its forward end or coupling end to provide a recess 4, and a bushing 5 having a hole 6 in alignment with the extension of the bore 2 is inserted into the recess 4. FIG. 1 also shows the front end of a punch 7 having a hole 8 for receiving the optical fibre 3.
The bushing 5 is made of a
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patent: 4190317 (1980-02-01), Makuch
patent: 4205896 (1980-06-01), Borsuk
patent: 4383736 (1983-05-01), Forman
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Healy Brian M.
Sikes William L.
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