Hot Water Straightening Light Guides Procedure

Overview

The optical fibers received from Saint Gobain Crystals are shipped via large diameter cardboard spools. As a result the optical fibers, when unspooled, tend to have an intrinsic curvature to them. It is very difficult to manipulate thirty 5+ foot curved fibers during bundle construction. For this reason the fibers are first straightened using a heat treating process. This process not only helps to alleviate stresses within the fibers due to the manufacturing process. By minimizing the internal stress of the fibers we can reduce the risk of crazing or fracture that otherwise might occur during the bundle manufacturing process.

Procedures

• Note: the fiber straightening procedure will require 2 technicians.

• Make room at a table for the aluminum U bar.

• If the Unistrut bar is not in the heat treating pipe, and if the collars have been removed, set out:
  • 6 or 7 light guide collars
  • 12 or 14 half inch 440 screws.
  • Bundling tool
  • aluminum bar

• Don a clean pair of gloves

• If the aluminum bar has just been removed from the heat treating pipe, it will still have a bundle of straightened fibers on it. In this case you may not need extra collars and screws. Unscrew the collars and remove the straightened bundle. Before putting a new bundle on the aluminum bar, clean the straightened bundle with a damp lint-free rag and put it, labeled, in the intermediate storage box.

• Move 30 rough cut light guides from the intermediate storage box to the table where you will bundle the fibers.

• Bundle the light guides into the anchoring collar at one end of the aluminum bar where there are no springs between the collar and the end of the bar.
  • Use the bundling tool to arrange the fibers into a 5x6 matrix. Rotate the bundle so that the fibers will fit in the anchoring collar. Screw the upper half of the collar to the lower half, but not too tightly. You want the fibers to be able to move lengthwise through the collar.
  • Use the flat face of a piece of aluminum to align the ends of the fibers so they all project the same distance beyond the anchoring collar, about a half inch. One worker may hold the metal, while the other pushes the fibers against it. Tighten the anchoring collar around the bundle so it will not slip.

• Run your gloved fingers along the fiber towards the next collar, keeping the fibers in the same position of the matrix. If constant pressure is kept on the top, bottom, and sides of the bundle with your hands, the bundle stays in a square matrix and is able to be placed in the next collar very easily.