Alcatel

Daniel D Uhm

Robert A Spencer

The present invention provides a fiber optic draw furnace having a fiber optic heating and draw control system that controls the heating of a fiber optic preform which is partially melted by a furnace and the drawing of an optical fiber from the fiber optic preform by a fiber drawing device. The fiber optic heating and draw control system features a fiber optic heating and drawing device controller that responds to a furnace power consumption control signal from a fiber optic preform heating device in the furnace, for providing a furnace heating control signal to the fiber optic preform heating device in the furnace and a fiber tension draw control signal to the fiber drawing device to maintain a desired fiber draw tension on the optical fiber. In one embodiment, the fiber optic heating and drawing device controller is a programmable logic controller. One advantage of the present invention is that it eliminates the need for an optical pyrometer port, which results in a symmetrical temperature profile around the circumference of the preform and also helps eliminate induced stresses that can cause defects in an optical fiber.

Fiber optic draw furnace featuring a fiber optic preform heating and fiber drawing programmable logic controller

The present invention provides an improvement to a fiber optic draw furnace having a heating element (,) arranged inside a furnace shell (,) for drawing an optical fiber (F) from a preform (P). The fiber optic draw furnace (,) has one or more pieces of fiber draw furnace insulation (,) to separate the heating element (,) from the furnace shell (,) for reducing the thermal transfer therebetween. At least one of the pieces of fiber draw furnace insulation (,) is made from rigidified high purity graphite felt that provides highly efficient thermal insulation between the heating element (,) and the outer furnace shell (,). The rigidified high purity graphite felt insulation (,), (,) includes either a bottom insulation ring (,), a cylindrical insulation insert (,) or a cylindrical insulation canister (,).

Fiber optic draw furnace having a heating element and a furnace shell, featuring rigidified high purity graphite felt insulation therebetween

A fiber draw furnace for drawing a fiber from a preform has a thermographic sensor in combination with a thermographic profiling processor. The thermographic sensor responds to infrared energy radiating from the fiber, for providing a thermographic sensor signal containing information about the infrared energy radiating from the fiber. The thermographic profiling processor responds to the thermographic sensor signal, for providing a thermographic profiling processor signal containing information about a thermographic profile of variations in the heat emitted across the width or along the length of the fiber. The fiber is typically quartz glass. The thermographic sensor includes an infrared filter and lens combination for filtering out infrared energy outside a range of 8-12 microns radiating from the quartz fiber. The thermographic sensor includes a lens and an infrared sensor for focusing and sensing infrared energy inside a range of 8-12 microns radiating from the quartz fiber. The quartz fiber typically has a temperature in a range of 500 to 2,000 degrees Celsius. The thermographic sensor signal contains information about the infrared energy radiating from the quartz fiber in a temperature range of 500 to 2,000 degrees Celsius.

Infrared high temperature measurement of optical fiber during draw

The present invention provides an improvement to a fiber optic draw furnace for drawing an optical fiber from a preform. The fiber optic draw furnace has a heating element having a shape for enclosing and heating the preform, and has a graphite liner having a corresponding shape to the shape of the heating element for providing a barrier between the heating element and the preform. In the fiber optic draw furnace, either the graphite liner is a high density extruded graphite liner that is impregnated with vitreous carbon completely through its entire graphite liner matrix, or the heating element is a high density extruded graphite heating element that is impregnated with vitreous carbon completely through its entire graphite heating element matrix, or both.

Impregnated vitreous (glassy) carbon graphite liner and heating element

An optical fiber furnace having an access port for a preform is disclosed. The access port includes a gas pressure generation and sensing device and an automatic shutter door assembly. The gas pressure generation and sensing device responds to a sensed gas pressure built up around a new preform being inserted into the optical fiber furnace, for providing an automatic shutter door opening signal. The gas pressure generation and sensing device also responds to a sensed outwardly flowing purge gas pressure escaping around an exhausted preform being removed from the optical fiber furnace, for providing an automatic shutter door closing signal. The automatic shutter door assembly responds to the automatic shutter door opening signal, for opening the automatic shutter door assembly for inserting the new preform into the optical fiber furnace. The automatic shutter door assembly also responds to the automatic shutter door closing signal, for closing the automatic shutter door assembly after removing the exhausted preform from the optical fiber furnace.

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Cornelius, NC, United States of America

Daniel D Uhm