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Fiber Polishing Procedure (view source)
Revision as of 14:31, 5 January 2018
, 14:31, 5 January 2018Adding information on the updated polishing procedure that uses the grinding wheel. The information for the old procedure is now at the bottom of the page.
Micah Warren | August 21, 2017
==General guidelines==
In all cases, the bundle should be kept at the center of the grinding wheel. This makes it easier to control the bundle, because the wheel isn’t on quite straight, and it wiggles less at the center than at the sides. Always use gentle pressure when holding the bundle against the wheel, just enough to keep it touching the wheel. Even gentler pressure is helpful when using finer grits, so little that the fibers may not even always touch the wheel, because of the wobble of the wheel. The fibers really do look better after a little time with gentle pressure, because the grit doesn’t dig in as deep. On the plastic grits (at least the five micron grit), it can be helpful to move the bundle around a little bit on the wheel, so as to grind the bundle in different directions. This helps remove striations.
==Light Guides==
The light guides should be bundled so that they stick out of the end collar by 0.1 inch.
===For the fuse (upstream, non-elastic) end===
*400 grit: take off whatever you need in order to bottom out to the 14-16 thousandths of an inch feeler gauge. Use speed 30 on the grinding wheel.
*1000 grit: take off ~8 thousandths of an inch, to bottom out to the 8 thousandths of an inch feeler gauge. When you are near the end, be sure to use just extra gentle pressure. By the end, the bundle should have only fine striations, and even those should be glossy. Speed 15 is good.
*5 micron: take off about whatever you need to make the bundle look smooth and shiny (maybe 3 thousandths of an inch). Use speed 15.
*Paper: just for a couple minutes. Speed 15 is good; be gentle and center the bundle. Only use paper if the fibers don’t look good enough after the five micron grit. (Sometimes you can even get away without using even the five micron grit.) The bundle should be nice and shiny, with minimal striations.
===For the SiPM (downstream, elastic) end===
All the techniques are the same as for the upstream end; only the distances change:
*400 grit: take off whatever you need in order to bottom out to the 16 thousandths of an inch feeler gauge. Use speed 30 on the grinding wheel.
*1000 grit: take off 8 thousandths of an inch, to bottom out to the 8 thousandths of an inch feeler gauge. When you are near the end, be sure to use just extra gentle pressure. By the end, the bundle should have only fine striations, and even those should be glossy. Speed 15 is good.
*There’s no need to use a feeler gauge with the rest of the grits. Just polish with each grit until it looks like the bundle is a good as that grit will get it.
==Scintillating Fibers==
[This has yet to be written. For now, see the [[https://docs.google.com/document/d/1lTzhqt9KMahyBxVGTfyB8EtZjd1UG3V5iKoimt5Nie4/edit?usp=sharing preliminary polishing information]].]
=Old Procedure (Used Before Summer '17)=
==Overview==
==Overview==
The non fused ends of each fiber must be polished to a mirrored finish. This allows the greatest amount of light transmission through the end of the fiber. Fibers are polished in their appropriate collars, SciFis in their 6x6 collar and light guides in their 5x6 collar. Polishing bundled fibers in their collars affords a number of advantages, the main ones being square fiber ends and minimal cladding flaring. Because the fibers are polished in their collars, it is important that the fiber ends are flush with one another. The scintillating fibers are easily made flush in their collar, but with light guides it is not so easy. For this reason, the light guides are polished as soon as they are returned from end-milling and while they are still in their collars.
The non fused ends of each fiber must be polished to a mirrored finish. This allows the greatest amount of light transmission through the end of the fiber. Fibers are polished in their appropriate collars, SciFis in their 6x6 collar and light guides in their 5x6 collar. Polishing bundled fibers in their collars affords a number of advantages, the main ones being square fiber ends and minimal cladding flaring. Because the fibers are polished in their collars, it is important that the fiber ends are flush with one another. The scintillating fibers are easily made flush in their collar, but with light guides it is not so easy. For this reason, the light guides are polished as soon as they are returned from end-milling and while they are still in their collars.