Abstract: A coating is applied on an optical fiber drawn from a melted tip of an optical-fiber preform. A glass spin is applied to a coated optical fiber by gripping the coated optical fiber with at least a pair of spinning applying rollers arranged in different levels with parallel rotation axes, rotating the spinning applying rollers so that the coated optical fiber is guided in a predetermined direction, and alternately shifting the spinning applying rollers in opposite directions along the rotation axes. The glass spin is applied to the coated optical fiber in a state in which each of the rotation axes is tilted at a predetermined angle from a plane perpendicular to the first direction.

Abstract: A coating is applied on an optical fiber drawn from a melted tip of an optical-fiber preform. A glass spin is applied to a coated optical fiber by gripping the coated optical fiber with at least a pair of spinning applying rollers arranged in different levels with parallel rotation axes, rotating the spinning applying rollers so that the coated optical fiber is guided in a predetermined direction, and alternately shifting the spinning applying rollers in opposite directions along the rotation axes. The glass spin is applied to the coated optical fiber in a state in which each of the rotation axes is tilted at a predetermined angle from a plane perpendicular to the first direction.

Abstract: Optical fiber manufacturing methods, which manufacture optical fibers with uniform characteristics using a simple device construction, are provided. The optical fiber manufacturing methods comprise, drawing a glass fiber from a glass preform by heating and melting one end of the glass preform and coating at least one layer of resin around the circumference of the drawn glass fiber. The method includes the steps of decreasing the viscosity of the resin from an initial viscosity during a start-up process time to a steady viscosity as optical fiber draw speed increases, wherein the steady viscosity is a predetermined viscosity; and increasing the draw speed during the start-up process time to a faster steady speed.

Abstract: A coating is applied on an optical fiber drawn from a melted tip of an optical-fiber preform. A glass spin is applied to a coated optical fiber by gripping the coated optical fiber with at least a pair of spinning applying rollers arranged in different levels with parallel rotation axes, rotating the spinning applying rollers so that the coated optical fiber is guided in a predetermined direction, and alternately shifting the spinning applying rollers in opposite directions along the rotation axes. The glass spin is applied to the coated optical fiber in a state in which each of the rotation axes is tilted at a predetermined angle from a plane perpendicular to the first direction.

Abstract: A guide hole guides a primary-coated optical fiber to a tubular inlet hole. An inner diameter of the guide hole is larger than that of the tubular inlet hole. An inner diameter of the tubular inlet hole is in a range from 1.5 times to 2.0 times that of the primary-coated optical fiber. A length of the tubular inlet hole is in a range from 1.0 mm to 2.0 mm. A depth of the guide hole is in a range from 2.0 mm 9.0 mm. A relation B?A is satisfied, with B equal to or larger than 7.0 mm, where A is an inner diameter of a leading edge of the guide hole continued to a trailing edge of the tubular inlet hole, and B is an inner diameter of a trailing edge of the guide hole.

Abstract: A guide hole guides a primary-coated optical fiber to a tubular inlet hole. An inner diameter of the guide hole is larger than that of the tubular inlet hole. An inner diameter of the tubular inlet hole is in a range from 1.5 times to 2.0 times that of the primary-coated optical fiber. A length of the tubular inlet hole is in a range from 1.0 mm to 2.0 mm. A depth of the guide hole is in a range from 2.0 mm 9.0 mm. A relation B?A is satisfied, with B equal to or larger than 7.0 mm, where A is an inner diameter of a leading edge of the guide hole continued to a trailing edge of the tubular inlet hole, and B is an inner diameter of a trailing edge of the guide hole.