[Yokozawa, Yuzurihara, Yamamura]
Abstract
We checked if scattered light noise could be seen when mirrors (PRM, PR2, PR3) moved, and we collected data.
We excited "K1:VIS-{PRM, PR3, PR2}_TM_TEST_L_EXC" channles with 1000 ~ 12000 cnts.
Figure 1,2,3 shows an example of q-transform when we excited PRM, PR2, and PR3, respectively.
The channel we used in these figures is out-of-loop PD.
Our goal
We want to make segment to show the presence of scattered light using out-of-loop channels.
Detail
2023/12/07
First, we set LSC-LOCK_STATE to "PRMI_TRANSITION_TO_1FSIG".
21:15 UTC; started excitation to "K1:VIS-PRM_TM_TEST_L_EXC" with 3000 cnts
21:32 UTC; with 6000 cnts
21:39 UTC; with 12000 cnts
21:44 UTC; stopped excitation
21:46 UTC; started excitation "K1:VIS-PR2_TM_TEST_L_EXC" with 1000 cnts
21:47 UTC; with 3000 cnts
22:02 UTC; stopped excitation ---> lockloss
22:10 UTC; started excitation "K1:VIS-PR3_TM_TEST_L_EXC" with 1000 cnts
22:11 UTC; lockloss
22:19 UTC; started excitation "K1:VIS-PR3_TM_TEST_L_EXC" with 2000 cnts
22:28 UTC; stopped excitation.
We used 0.42 Hz to excite the mirrors.
It is the frequency of the scattered light noise during O4a.
We did an additional experiment with a different frequency, 0.2 Hz.
However, the periods of arches were not different so much from the previous experiment. (Figure)
Ushiba-san commented that that was because we excited the TM,
even though the source of the scattered light noise was not at the resonance frequency of the TM itself but that of the pendulum.
In addition, there was much time when the scattered light could not seen even though we excited the mirrors.
Our goal is to make a SEGMENT (binary flag) that tells when the scattered light noise occured, and these experiments were done to collect test data.
----------------------------
2023/12/11
First, we requested LSC-LOCK_STATE to "PRMI_TRANSITION_TO_1FSIG".
Reprodeced previous experiment (0.42 Hz)
22:03 UTC; excited "K1:VIS-PRM_TM_TEST_L_EXC" with 3000 cnts [PRM moved ~ 2 um ]
22:10 UTC; with 6000 cnts [~ 3 um]
22:15 UTC; with 12000 cnts [~ 3 um]
22:20 UTC; stopped excitation
22:22 UTC; excited "K1:VIS-PR2_TM_TEST_L_EXC" with 1000 cnts [PR2 moved ~ 2 um]
22:27 UTC; with 2000 cnts [~ 3.8 um]
22:32 UTC; stopped excitation
----------------------------------------------------
changed the frequency to 0.2 Hz.
22:33 UTC; excited "K1:VIS-PRM_TM_TEST_L_EXC" with 6000 cnts [PRM moved ~ 1.5 um]
22:38 UTC; with 12000 cnts [ ~ 2.5 um]
22:43 UTC; stopped
22:44 UTC; excited "K1:VIS-PR2_TM_TEST_L_EXC" with 1000 cnts [PR2 moved ~ 1.5 um ]
22:49 UTC; stopped
22:50 UTC; excited "K1:VIS-PR3_TM_TEST_L_EXC" with 1000 cnts [PR3 moved ~ 2 um]
22:55 UTC; with 2000 cnts --> lockloss
23:03 UTC; excited "K1:VIS-PR2_TM_TEST_L_EXC" with 500 cnts [PR2 moved ~ 1 um ]
22:08 UTC; with 1500 cnts [ ~ 2 um ]
22:13 UTC; stopped
22:14 UTC; started excitation "K1:VIS-PR3_TM_TEST_L_EXC" with 500 cnts [PR3 moved ~ 1 um]
22:19 UTC; with 1500 cnts --> lockloss
22:35 UTC; started excitation "K1:VIS-PR3_TM_TEST_L_EXC" with 1500 cnts [PR3 moved ~ 2 um]
22:40 UTC; with 2000 cnts --> lockloss
(note: we checked "K1:VIS-{PRM,PR2,PR3}_TM_WIT_L_DQ" to know actual movements of the mirrors.)
22:10 UTC; with 6000 cnts [~ 3 um]
22:15 UTC; with 12000 cnts [~ 3 um]
Note that linearity between excitation and detected displacement was quite broken. I'm not sure that this have been because Oplev have been out of linear range or because injection have been able to be done as expected. Anyway, a written displacement doesn't help to understand the setup and situation of this measurement...