Abstract: An optical fibre tensioning device, receiving at its input an optical fibre from a traction device and capable of supplying the optical fibre from its output to a device for storing the fibre. The tensioning device comprises at least one fixed pulley on which the optical fibre is wound for a first length, and at least one movable pulley on which the optical fibre is wound for a second length. A device for measuring the tension applied to the fibre and a motorized device for moving the movable pulley interact with each other to control a distance (Dp) between axes of the pulleys in such a way as to automatically keep the tension applied to the fibre essentially constant.

Abstract: A device for manufacturing a preform for optical fibers is described, comprising a chemical deposition chamber including at least one gripping member rotatably mounted about an axis Z-Z and adapted to hold at least one end of at least one elongated element constituting a substrate for chemical deposition for forming a preform for optical fibers. The chamber further includes at least one burner which is mobile along a direction substantially parallel to said axis Z-Z and suitable for depositing, on said at least one elongated element, a chemical substance for forming a preform, and at least one suction element arranged on the opposite side to said at least one burner with respect to said axis Z-Z and adapted to collect and discharge, from said chemical deposition chamber, exhaust chemical substances.

Abstract: An induction furnace capable of drawing large diameter preforms of up to 130 mm is described. The induction furnace has top and bottom chimneys surrounding the entire preform during operation of the furnace with an inert conditioning gas which is introduced into the top chimney and flows downward through the furnace body and bottom chimney without significant turbulence. A distributor ring inside the top chimney redirects flow from a circumferential direction to a downward direction. The top chimney also includes a resilient seal to releasably hold the top of the preform. The bottom chimney has a smoothly decreasing cross-sectional area preventing turbulence at the furnace exit. The furnace insulation is preferably a rigid self-supporting graphite cylinder. A method of drawing large diameter preforms either to an optical fiber or to a preform of smaller diameter using such a furnace is also described.

Abstract: Optical fiber tensioning device, receiving at its input an optical fiber (35) from a traction device (37) and capable of supplying the optical fiber from its output to a device (40) for storing the fiber. The tensioning device (1) comprises at least one fixed pulley (32) on which the optical fiber (35) is wound, for a certain length at least, and at least one movable pulley (9) on which the optical fiber (35) is wound, for a certain length at least. A device for measuring the tension applied to the fiber and a motorized device (24, 26, 5, 7) for moving the movable pulley (9) interact with each other to control the distance (Dp) between the axes (33, 20) of the pulleys (32, 9) in such a way as to automatically keep the tension applied to the fiber essentially constant.