In the dark all fibers are no longer gray
Fibers in a flash
To make fibers easy to identify in a tube, we commonly use 12 colors. Beyond 12, we marked them with rings, which is slow and could be detrimental to FO quality. By using a transparent fluorescent coating, installers can use a UV light to recognize fibers 13 to 24.
Standard UV curable transparent resin charged with fluorescent powder is thinly applied on cables at speeds up to 1,000 m/minute. The technique could also be used for invisible anti-theft marking or for finding cables installed in dark places, like shafts or tunnels.
Finding the matrix
Non-continuous ring marking slows production and raises costs, and may negatively affect optical properties. The challenge was to find a pigment that could mix easily with acrylate resin coating as a matrix. Some pigments had bad mixing properties, changed viscosity of the resin, cured insufficiently or were opaque in sunlight. Finally, a low granulometry pigment was identified and a cable produced. Qualification tests included thermal cycles and coating adhesion, with hands-on installation done by fitters under real conditions.
Besides being easier and faster to produce, the method reduces defective scrap fibers due to ring marking. On the installers’ side, quick differentiation between two packets of 12 fibers will surely speed up the jointing process. Moreover, this will improve fiber identification in places where lighting is poor. Bearing in mind market evolution, which is seeing higher fiber density (up to 1,008 fibers in 22 mm cable) the next step will be to use more pigments to color 48 fibers and more, which will light up magically under ultraviolet light.
“A criminal investigation tool helps installers quickly identify optical fibers.”