Method and apparatus for measuring the diameter and/or eccentricity of a coating layer of a coated optical fiber

A method for measuring a diameter of a first coating layer of a coated optical fiber, the optical fiber being coated with the first coating layer and with a second coating layer, the method comprising the steps of:

• projecting a beam of light onto the coated optical fiber in a direction substantially perpendicular to a central axis of the coated optical fiber;
• receiving light projected onto the coated optical fiber after the light has passed through the coated optical fiber;
• focusing the received light onto an optical detector positioned substantially perpendicular to a central axis of the coated optical fiber, the optical detector comprising an array of photosensors, each photosensor corresponding to a pixel of the optical detector, each pixel having a pixel value associated with an amount of light impinging thereon, the optical detector generating an image of the coated optical fiber in response to the light focused thereon;
• processing the pixel values to determine the diameter of the first coating layer, the diameter of the first coating layer being determined by detecting at least a first bright region in the image and determining that said at least a first bright region corresponds to a first boundary between the first coating layer and the second coating layer;
• and
• utilizing a relative location of said at least one bright region in the image to determine the diameter of the first coating layer.

An optical fiber manufacturing system, the optical fiber manufacturing system comprising:

• a dual coating applicator for applying a first coating layer and a second coating layer to an optical fiber as the optical fiber passes through the coating applicator in an axial direction of the optical fiber from a first end of the coating applicator toward a second side of the coating applicator;
• a light source for projecting a beam of light onto the coated optical fiber in a direction substantially perpendicular to a central axis of the coated optical fiber, the light source being located downstream of the coating applicator with respect to the axial direction of movement of the optical fiber;
• a lens disposed opposite the light source and coaxially aligned with the light beam projected by the light source, the coated optical fiber being between the light source and the lens, the lens receiving light projected by the light source that passes through the coated optical fiber;
• an optical detector positioned to receive light focused by the lens onto the optical detector, the optical detector comprising an array of photosensors, each photosensor corresponding to a pixel of the optical detector, each pixel having a pixel value associated with an amount of light impinging thereon, wherein the optical detector generates an image of the coated optical fiber in response to the light focused thereon by the lens;
• and
• a signal processor electrically coupled to the optical detector, the signal processor receiving the pixel values from the optical detector and processing the pixel values to determine the diameter of the first coating layer, the signal processor determining the diameter of the first coating layer by detecting at least one bright region in the image and determining that said at least one bright region corresponds to a boundary between the first coating layer and the second coating layer, the signal processor utilizing a relative location of said at least one bright region in the image to determine the diameter of the first coating layer.