Optical cables
AssigneeNorthern Telecom Limited
InventorsFrederick D. King, Tomasz S. Swiecicki
Life of this patent
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Abstract
An optical cable has a grooved central filament, the grooves following helical paths, the helices changing hand along the filament. In the manufacture of the filament, plastics is extruded past a fixed die and some way downstream, the filament is held and twisted first in one direction and then in the opposite direction so that the helical paths are introduced where the plastics exits the die. Dielectric optical waveguides are disposed in the grooves and the whole is surrounded by an extruded plastic sheath to produce an optical cable.
Claims9
Apparatus for making an optical cable filament comprising extrusion means having a fixed die formed with a multi-fingered aperture to impart a grooved surface to plastics extruded therethrough, twist means located downstream of said extrusion means, said twist means having a member mounted for reciprocal rotation about a feedpath for the filament, the member having engaging means for engaging the filament and being driveable to twist the filament to impart a helical form to the grooves where extruded plastics exits the die.
Dependencies are inferred from the claim text.