Mirror replacement -- Success!

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Quick conclusion: We swapped all the silver coated mirrors on HWS X and Y table (18 total, 9 per table). Stream images now look better compared to what we used to have (alog28624)

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Details:

Livingston found their mirrors to be contaminated (alog27041) so we went out to check ours and discovered similar (if not the same) issue (alog28624). Today we swapped out all the silver coated mirrors and realign them following procedure in T1600329. The old mirrors are covered with dust and tiny particulates that won't get blown away by compressed air. Some mirrors are covered with scratches that couldn't have happened naturally (not just by sitting on the table). Some have tiny holes that almost look like damages from laser. Tomorrow Jason will try to drag wipe some of the mirrors to see if the particulates can be cleaned.

Below are some pictures of the old mirrors we pulled out.

We inspected every new mirrors for dust and scratches. They didn't come perfect. Some have tiny holes in them and dust that couldn't be blowned away. But overall the new mirror set is a huge improvement of what we pulled out.

Here are some photos of the new mirrors. These defects pretty much represent the whole batch. Only a few came without any defects at all.

Below are screenshots of the stream images after the mirror swap. Much better compared to alog28624

ITMX

ITMY

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HWS code status

Since I will be gone for a whlie and the thinning code isn't quite ready for action, I removed a bunch of old ETMS data to make room enough for 3+ weeks. None of the HWS codes are running right now since it wouldn't be writing useful data. Somebody will have to restart the code once the IFO is ready to go again.

Images attached to this report