Apparatus and methods for accurate high-speed marking of optical fibers

The apparatus and methods include moving an optical fiber over a fiber path that includes a marking location at which resides a marking unit that dispenses an ink-jet stream. A centering method is performed whereby the optical fiber is incrementally moved in a lateral direction through the path of the ink-stream and the mark number density of marks formed on the optical fiber is measured along with the optical fiber position. A process window is defined by the range of lateral fiber positions over which a target mark number density is formed on a consistent basis. A controller calculates an optimum fiber path position and stores it memory for future reference while also moving the fiber path to the optimum position. The initially wet ink marks are dried and the fiber coated with a transparent protective overcoat to form a coated and marked optical fiber.