Long hot zone furnace element and optical fiber drawing method practiced therewith
AssigneeCorning Incorporated
InventorJackson P. Trentelman
Life of this patent
Estimating the term…
Abstract
The disclosed invention is a rotationally symmetrical resistance furnace heating element. The heating element has at least two ends. A respective cooling element is disposed in communication with each end. The heating element includes at least first and second high current density sections. The high current density sections are axially separated by at least one low current density section. The high current density sections have a smaller diameter than the low current density section. The invention also includes a multiple crucible method of drawing an optical fiber from the draw furnace described above. The method includes the step of heating an entire body of raw materials in a hot zone in the furnace.
Claims23
A rotationally symmetrical resistance furnace heating element having at least two ends comprising:
- at least first and second high current density sections axially separated by at least one low current density section, said high current density sections having a smaller diameter than said low current density section, and a current density of said low current density section is less than a current density of each high current density sections;
- and
- a cooling element containing a circulating coolant at each end of said heating element.
A rotationally symmetrical resistance furnace heating element having at least two ends and a cooling element at each end, said heating element comprising:
- at least first and second high current density sections axially separated by at least one low current density section, each of said high density sections has a thickness of no more than 3 mm, said low density section has a thickness of at least 4 mm, said high current density sections having a smaller diameter than said low current density section, and a current density of said low current density section is less than a current density of each high current density sections;
- said cooling elements each containing a circulating coolant.
A method of making an optical fiber comprising:
- feeding raw materials for making an optical fiber into a multiple crucible apparatus forming a body of raw materials;
- heating the body of raw materials with a furnace having a rotationally symmetrical resistance furnace heating element, the heating element having at least two ends and a cooling element at each end, the heating element comprises at least first and second high current density sections axially separated by at least one low current density section, the high current density sections having a smaller diameter than the low current density section, and a current density of the low current density section is less than a current density of each high current density sections;
- cooling each of the two ends of the heating element by circulating a coolant within each of the cooling elements;
- and
- drawing an optical fiber from the multiple crucible apparatus.
A rotationally symmetrical resistance furnace heating element having at least two ends said heating element comprising:
- at least first and second high current density sections axially separated by at least one low current density section, said high current density sections having a smaller diameter than said low current density section, and a current density of said low current density section is less than a current density of each high current density sections;
- and
- a cooling element containing a circulating coolant wherein the coolant is water at each one of the two ends of the resistance furnace heating element.
Dependencies are inferred from the claim text.