Methods of and apparatus for coating optical fibers

Claim 1

A method of providing a coated optical fiber, said method including the steps of: providing an optical fiber preform to be drawn; heating the preform in a furnace and drawing an optical fiber therefrom; coating the drawn optical fiber, the step of coating the fiber comprising the sub-steps of: (a) moving the drawn optical fiber from the furnace into and through an entry plenum, through a cross-flow manifold which is disposed adjacent to a fiber entry end of an elongated coating deposition chamber having a longitudinal axis and then through the deposition chamber while the drawn optical fiber is within a predetermined temperature range above ambient and then out of the deposition chamber through an exit plenum positioned at the end of the deposition chamber opposite its entry end, the entry and exit plenums each having optical fiber entry and exit orifices through which the optical fiber is moved into and out of each plenum, the entry and exit plenums, cross-flow manifold and coating deposition chamber being connected together such that the fiber will not be subjected to external air; (b) causing a reactive gas, which when subjected to said predetermined temperature range reacts to provide a reaction product, to be moved into the deposition chamber; (c) causing the reactive gas to engage the drawn optical fiber within the coating deposition chamber while the drawn optical fiber is within the predetermined temperature range whereupon the reactive gas reacts upon contacting the drawn optical fiber to thereby provide a reaction product that coats the fiber and a suspended soot; (d) purging the entry and the exit plenums of the coating deposition chamber each with a purge gas (1) to prevent external air from entering the entry orifice of the entry plenum and the exit orifice of the exit plenum and further (2) to prevent the movement of reactive gas from the coating deposition chamber into the entry plenum through the fiber exit orifice of the entry plenum and into the exit plenum through the fiber entry orifice of the exit plenum; and (e) causing a cross-flow gas to be flowed into, through and out of said cross-flow manifold, the flow of the cross-flow gas being perpendicular to said longitudinal axis of the coating deposition chamber, and directly in between the fiber exit orifice of the entry plenum and the fiber entry end of the elongated coating deposition chamber, wherein the cross-flow gas prevents an accumulation of the soot comprising reaction products of the reactive gas at the fiber exit orifice of the entry plenum adjacent to the entrance of the coating deposition chamber and wherein the reactive gas and suspended soot are exhausted with the cross-flow gas perpendicularly to said longitudinal axis of the coating deposition chamber; and taking-up the coated optical fiber.

Claim 2

A method of providing a coated optical fiber, said method including the steps of: providing an optical fiber preform to be drawn; heating the preform in a furnace and drawing an optical fiber therefrom; coating the drawn optical fiber, the step of coating the fiber comprising the sub-steps of: (a) moving the drawn optical fiber from the furnace into and through an entry plenum, through a cross-flow manifold which is disposed adjacent to a fiber entry end of an elongated coating deposition chamber having a longitudinal axis and then through the deposition chamber while the drawn optical fiber is within a predetermined temperature range above ambient and then out of the deposition chamber through an exit plenum positioned at the end of the deposition chamber opposite its entry end, the entry and exit plenums each having optical fiber entry and exit orifices through which the optical fiber is moved into and out of each plenum, the entry and exit plenums, cross-flow manifold and coating deposition chamber being connected together such that the fiber will not be subjected to external air; (b) causing a reactive gas, which when subjected to said predetermined temperature range reacts to provide a reaction product, to be moved into the deposition chamber; (c) causing the reactive gas to engage the drawn optical fiber within the coating deposition chamber while the drawn optical fiber is within the predetermined temperature range whereupon the reactive gas reacts upon contacting the drawn optical fiber to thereby provide a reaction product that coats the fiber and a suspended soot; (d) purging the entry and the exit plenums of the coating deposition chamber each with a purge gas (1) to prevent external air from entering the entry orifice of the entry plenum and the exit orifice of the exit plenum and further (2) to prevent the movement of reactive gas from the coating deposition chamber into the entry plenum through the fiber exit orifice of the entry plenum and into the exit plenum through the fiber entry orifice of the exit plenum; and (e) causing a cross-flow gas to be flowed into, through and out of said cross-flow manifold, the flow of the cross-flow gas being perpendicular to said longitudinal axis of the coating deposition chamber, and directly in between the fiber exit orifice of the entry plenum and the fiber entry end of the elongated coating deposition chamber, wherein the cross-flow gas prevents an accumulation of the soot comprising reaction products of the reactive gas at the fiber exit orifice of the entry plenum adjacent to the entrance of the coating deposition chamber and wherein the reactive gas and suspended soot are exhausted with the cross-flow gas perpendicularly to said longitudinal axis of the coating deposition chamber; and taking-up the coated optical fiber.