Hot Water Fiber Bending Procedure

Overview

The light guide is offset soon after the SciFi section in an S-bend to reduce the amount of fiber exposed to the electrons' trajectory. Fibers are placed within a water tank, heated with the water, then bent and cool within the tank. The process takes many hours.

Procedure

Measurement

Before beginning the bending procedure, you will first need to determine the most appropriate position for the fibers in the particular bundle you are constructing. The cross-sectional width of the fuse sites vary from fiber to fiber. To avoid having a row or column in the bundle that is larger or smaller than another, fuse site measurements are made and fiber position is optimized. The orientation of the fibers are noted in the Bundle Names Google document and labeled so that orientation can be controlled for the bending process, effectively choosing the final position of the fiber in the bundle.

Orientation

• First ensure that each part of the bending unit is clean and don a pair of powder-free gloves.

• Be sure that the chimneys and the bottom halves of the collars are attached to their appropriate plates.

• Open the intermediate storage box and remove the fibers you will be bending. Place these fibers on a flat surface, always being cautious with the fuse site.
• Use the bundling tool to place the fibers in the correct orientation and position as defined by the Bundle Names Google Document.
  • Note: Because the bundling tool is 5 fibers wide and 6 fibers high, and the collars are 6 fibers wide and 5 fibers high, the bundling tool must be rotated when placing fibers in the collars. Therefore when the bundling tool is used, the fibers should be put in columns first with the orientation opposite of what is stated in the Google Doc, and their order rotated 90 degrees. For example if the final position and (orientation) of the fibers is:

OB(a) - OH(a) - ON(a) - OE(a) - OJ(a) - OO(a)
O4(a) - O9(a) - O14(a)- OD(a) - OI(a) - O15(a)
O3(a) - O8(a) - O13(a)- OC(a) - O10(a)- OM(a)
O2(a) - O7(a) - O12(a)- O5(a) - OG(a) - OL(a)
O1(a) - O6(a) - O11(a)- OA(a) - OF(a) - OK(a)

Then they should be placed in the bundling tool as:

OO(b) - O15(b)- OM(b) - OL(b) - OK(b)
OJ(b) - OI(b) - O10(b)- OG(b) - OF(b)
OE(b) - OD(b) - OC(b) - O5(b) - OA(b)
ON(b) - O14(b)- 013(b)- 012(b)- 011(b)
OH(b) - O9(b) - O8(b) - O7(b) - O6(b)
OB(b) - O4(b) - O3(b) - O2(b) - O1(b)

• Put a collar around the bundle so that it is secure around the fibers but does not cause damage. The fibers should not be able to slide through, rotate, or change orientation.
  • Note: While working with one end of the bundle, always be cautious of the other end. Any bends may cause damage to the fiber.

Placement into Collars

Securing the Orientation

It's important for bending to make sure the scintillating end of the fibers are square and flush. This process usually requires 2 technicians.

• Start by placing a flat block in front of the bundle and secure the collar onto the bending unit. Have one technician hold the flat block in place (or clamp the block to the table.)
  • Loosen the collar around the bundle enough to the fibers to slide but not change orientation.
• Gently take each fiber and push it through the collar so that it butts up against the flat block. If you have a second technician with you, have them watch the fuse sites and you'll be able to see when all the fibers are flush.
  • Note: Be sure not to strain any of the fibers during this process!
  • When you are certain that the fibers are flush against the block, carefully tighten the chimney around the bundle so that the fibers neither slide nor change orientation. If you see that any fibers are offset by more than ~.5mm, repeat this process.

Offsetting the Fibers

The next step involves offsetting the SciFi end past the bending unit. This will compensate for the length of fiber required to produce the S-bend.

• Cautious of the fiber orientation of the bundle, secure the second collar around the bundle.
• Make sure the first collar (the collar closest to the popsicle stick) is tight enough to hold the fibers in place without slipping. Detach the first collar from the bending plate.
• Loosen the second collar so that the fibers may slide through it without damage or change in orientation.
• Slide the first collar so that the fibers are flush against the edge of the bending plate.
• Tighten the second collar so that the fibers do not slide.
• Loose the first collar so it may slide along the fibers. Move it to the "start" position as labelled on the bending plate and then tighten it again so the fibers do not slide or change orientation.
• Loosen the second collar and move the first collar to the "finish position". This moves the fibers one inch past the bending unit plate to compensate for the length of fiber needed to produce the S-bend. This is also the final horizontal position of the fibers for the entirety of the bending process.
• Tighten the second collar and all collars after (third through seventh). Loosen the first collar, and re-attach it to the bending unit plate and then tighten it.
  • At this point, all seven collars should be tight around the bundle, and attached to the bending unit.

Placement into Chimneys

• Using a clamp, secure Bending Plate #2 to the bending bar so that the fibers ends are flush with the edge of the farthest chimney.
  • From this point onward, be wary of the fibers and the chimneys. The chimneys are sharp may cause damage to the fibers if they are caught in a chimney slot and strained.
• Using a straight zip-tie (or any other straight, thin piece of plastic), separate the fibers (which should be in a 6x5 matrix) into 6 columns of 5 fibers each. Place a strip of paper in between each column in the meantime.
• As viewed looking at the SciFi end, take the right-most column and place it in the chimneys. The bottom fiber goes in the right-most spot on the chimney, and you move left as you progress. Take the next right-most column and repeat.
  • Only 3 columns of 5 fiber each will be placed into Bending Plate #2.
  • Do not push or force any fiber into a chimney slot as this will cause damage to the fiber!
    • If a fiber does not fit into a chimney slot, use a small file to widen the slot. Make sure it is large enough that the fiber seeds into the chimney slot with no resistance.
• Make sure that the lightguide fibers reach to the very end of the chimney on plate #2. If they do not, move the plates and the bar until the lightguides reach the end of the chimney AND the bar (and its blocks) are able to fit between the metal tubes on the plates.
  • This step is important as it sets the distance the plates will remain from each other as well as the bend in the fibers.
• Place a chimney clamp on top of the first chimney (closest to the collars/popsicle stick) and secure it in place with 3 screws.
  • The chimney clamp holes are dependent on orientation. Both the chimneys and chimney clamps are marked on one side. Lining up marks gives the orientation that the chimney plate should be attached.
    • If any of the screws resist while the chimney clamps are being installed back the screw out and try a different screw. If the screw still resists, try moving the chimney clamp to better line up the holes on the chimney and chimney clamp. Forcing a screw will lead to cross threading and ruin the chimney!
• Record the orientation and fiber name of each slot in the chimney in the Bundle Names Google doc. Here you may check that you have not altered the orientation of the fiber matrix.
• With extreme care, cut off the main portion of the fiber tag with scissors. Afterwards, remove the rest of the fiber tag with your hands and remove the remaining adhesive glue with a dry lint-free cloth.
• Secure the rest of the chimney clamps on the rest of the chimneys of Bundle Plate #2. Do not screw them down so tight that they damage the fibers, but do secure them enough so that no fibers can slide out of their slots.

• Place Bending Plate #1 on top of Bending Plate #2 and the bending bar.
  • Be sure to align the chimneys on plate #1 directly above the chimneys on plate #2.
• Secure both plates to the bar with clamps.
• Repeat the process for placing fibers in the chimney slots. Again starting with the right-most column, and the bottom fiber going into the right-most slot. Repeat the chimney and tag-removing process.

Filling and Siphoning the Tank

Make sure that the pumps and heaters are off for this step!

• It is important that the water be clean each time a new bundle is put into the water. As the pieces of the bending unit rust, the water needs to be changed and the tank cleaned each time a new bundle is to be bent.
• Once the tank has been drained and cleaned, open all of the valves near the right exclusion area including the inlet valve from the faucet.
• Turn on the cold water and let the tank fill.
• It will take about 30 minutes for the tank to fill high enough to immerse the fibers and bending unit. Fill the tank until the water reached the top of the highest horizontal 2x4.
• Once the tank is full you should wait for thirty minutes to allow any air bubbles to coalesce into bigger bubbles so they may be siphoned out.
  • Put the siphon completely underwater in the tank and pump it until no more air bubbles come out.
  • Keeping the siphon underwater put the hose into the inlet of the left exclusion area and pump the siphon until no air comes out of the outlet of the left exclusion area.