Method for manufacturing helical optical fiber
AssigneeBell Telephone Laboratories, Incorporated
InventorEnrique Alfredo Jose Marcatili
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Abstract
An optical cable which is relatively immune to the effects of bending and/or tension comprises a helical optical fiber loosely confined within a protective sheath. Apparatus is disclosed for fabricating the helical fiber. For example, as the fiber is drawn from a heated preform the fiber is subjected to periodic, pulsating jets of an inert gas, such as nitrogen, which physically deform the fiber into the desired helical configuration.
Claims9
A method of manufacturing an optical fiber in the form of an elongated helix, comprising the steps of:
- heating the lower extremity of a substantially vertically disposed preform to soften the preform;
- and
- drawing the optical fiber from said softened preform, said method being characterized by the further steps of:
- passing said optical fiber, while still in a softened state, through at least one pair of eccentrically rotatable rollers;
- and
- rotating said rollers in synchronism with the rate at which said fiber is drawn from the softened preform.
A method of manufacturing an optical fiber in the form of an elongated helix which comprises the steps of:
- heating the lower extremity of a substantially vertically disposed preform to soften the preform;
- and
- drawing the optical fiber from said softened preform, said method being characterized by the further steps of:
- positioning an upper portion of said preform within an aperture formed in a fixed member;
- positioning a lower portion of said preform within an aperture formed in a movable member;
- and
- moving said movable member in an oscillatory manner with respect to said fixed member whereby a corresponding oscillatory movement is induced in said preform, which oscillatory movement generates the desired helical configuration for the fiber.
A method of manufacturing an optical fiber in the form of an elongated helix, comprising the steps of:
- heating the lower extremity of a substantially vertically disposed preform to soften the preform;
- and
- drawing the optical fiber from said softened preform, characterized in that said preform heating step comprises:
- rotating a heat-source about said preform, the axis of rotation of said heat-source being parallel to, but spaced apart from, the longitudinal axis of said preform whereby said preform is asymmetrically heated, thereby to induce preferential melting of the preform and the desired helical configuration of the fiber drawn therefrom.
A method of converting a conventional optical fiber into an optical fiber having the configuration of a helix, characterized by the steps of:
- advancing said fiber past a source of heat to soften the fiber;
- passing said softened fiber through at least one pair of eccentrically rotatable rollers;
- and
- rotating said rollers in synchronism with the rate at which said fiber is drawn from the preform.
A method of converting a conventional optical fiber into an optical fiber having the configuration of a helix, characterized by the steps of:
- advancing said fiber past a source of heat to soften the fiber;
- passing said fiber through an aperture in a first guide means positioned upstream of said heat-source;
- passing said softened fiber through an aperture in a second guide means positioned downstream of said heat-source;
- and
- rotating said second guide means in a plane which is normal to the longitudinal axis of said fiber thereby rotating said aperture and inducing a helical twist in said fiber.
Dependencies are inferred from the claim text.