Corning Incorporated
Optical fiber coating die with reduced wetted length

Abstract:

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle .alpha., wherein 2.degree..ltoreq..alpha..ltoreq.25.degree., and a cone height L.sub.1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d.sub.2, wherein 0.1 mm.ltoreq.d.sub.2.ltoreq.0.5 mm and a cylindrical height of L.sub.2, wherein 0.05 mm.ltoreq.L.sub.2.ltoreq.1.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L.sub.5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L.sub.6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.