Forced convective cooling of optical fibers in high‐speed coating

The high‐speed coating of optical fibers must consider the possibility of a very hot fiber contacting coating material. In this case, the quality of coating may deteriorate if the fiber temperature is above a certain point. Hence, gas‐assisted cooling of fiber was investigated and its effectiveness compared with the self‐cooling case. A cylindrical air blower of 2.5 cm diameter and 20 cm length with a slit (0.2 cm×20 cm) along its axis was employed to cool the fiber entering the coating cup. Measured fiber cooling rates are compared to calculated ones and are in good agreement. It is shown that this technique can result in a twofold increase in coating speed without deteriorating the coating material.