stefan.ballmer@LIGO.ORG - posted 20:12, Tuesday 04 December 2018 - last comment - 11:36, Wednesday 05 December 2018(45699)
Green initial alignment references updated and ITMY green camera moved to recenter the spot
Keita, Stefan
We re-centered the green QPD offsets in full-lock (2W but with 20W soft offsets) and physically moved the Green camera back to the screen center. (work permit 7985 with Chandra's verbal approval).
WP is this one: https://services.ligo-la.caltech.edu/LHO/workpermits/view.php?permit_id=7985
We need a sturdier camera enclosure than this.
Green camera enclosure is the higher and smaller of two boxes in the attached picture.
The problem is that the entire structure is too flimsy.
You'll notice in the third picture that the screws for the lid of the enclosure are loose. Tightening these was unproductive as it twisted the structure, changing the camera pointing, and it was difficult to compensate for this by the manual adjustment of the camera (which, apparently, we have to do with the lid removed).
If you push the enclosure by your finger the camera pointing changes (though it mostly goes back to the original position after removing the pressure). If the tension of the cable coming out of the box changes probably the pointing changes though we haven't tested this.
This is really not a good system to be used as our initial alignment reference. It would be extremely useful if the camera enclosure is much sturdier (made out of metal plates instead of sheet metal, or sheet metal covering the rigid frame).
FRS 11931