aLIGO LHO Logbook

H1 SQZ (SQZ)

sheila.dwyer@LIGO.ORG - posted 18:16, Thursday 22 March 2018 - last comment - 09:21, Tuesday 27 March 2018(41119)

squeezer beam is not found yet...

Terry, Sheila, Arijit, TJ,

Today we made one more attempt to get the beam from the OPO aligned into HAM5 and out to HAM6, but we haven't found the beam.

Keita loaned us a Nikon D7100 which was much better for getting a clear picture of what we were looking at than the viewer we were using yesterday. Photos will be attached to this alog latter.

FIl also cabled the HAM5 illuminator up to the new beckhoff controls, so we could turn that on and off.

We started out by manually aligning the beam again through the apertures, doing a little bit more careful job this time by using the viewer to identify the edges of teh aperature and center the beam half way. We can still see the beam hitting ZM2 through the HAM5 viewport. We were also able to sometimes see the beam coming out the HAM5 viewport (perhaps going under the fly-offf mirror on the OFI), but latter this afternoon we weren't able to repeat that. We were never able to see a beam in HAM6.

We are leaving the OPO locked and generating a beam (we again have two soft door covers with a small gap to let the beam out). We have ZM1+ZM2 scanning with an amplitude of 10,000 counts for both pitch and yaw, and SRM scanning 1000 urad.

If this does not work, we may wait for a beam from the PSL to become available and try to see the rejected scatter from the OFI polarizer in the path towards the squeezer.

Comments related to this report

sheila.dwyer@LIGO.ORG - 13:09, Friday 23 March 2018 (41123)

Link

Here are some images to help clarify what we saw.

I can't find an up to date drawing of the HAM5 layout, but here is a preliminary drawing https://dcc.ligo.org/DocDB/0121/D1500303/002/HAM5.PNG, which shows ZM2 much further in the +y direction than it really is placed. In reality the beam from the OFI to ZM2 runs nearly parallel to the septum.

Here are some photos taken from the easternmost viewport on the north side of HAM 5 (the -y viewport on the +x side of HAM5). The first photo is a blurry overview of what we can see, the fly off mirror for the squeezed beam is in the center (there is a black glass clip on the back of the mirror), behind that you can see the cage of ZM2. The violet looking thing that is just peaking over the black glass clip is our beam or scatter from our beam.

The second photo shows that at some alignments on ZM1/ZM2, we can see a quite bright thing in HAM5 which is probably our beam. The fourth photo shows an alignment for ZM1 for which the beam clips on the bracket for the eddy current damper on ZM2, while the third photo shows an alignment of ZM1 where we think the beam should be hitting ZM2. You can see some difuse IR light, and what looks like the outline of the black glass clip in that scattered light. This seems like a good candidate for our best alignment, you might think that this scatter means that the beam is hitting or nearly hitting the fly off mirror with the black glass clip, however, we saw nothing in HAM6 for this alignment.

Images attached to this comment