Reports until 16:29, Tuesday 05 October 2021
H1 SQZ
sheila.dwyer@LIGO.ORG - posted 16:29, Tuesday 05 October 2021 - last comment - 10:35, Wednesday 06 October 2021(60139)
HAM7 activites today

Georgia, Keita, Camilla, Sheila, Jim

Here is an update about HAM7 activities today. 

C:L1 lens quick attempt at placement

We attempted to add the lens C:L1 to the squeezing to SQZT7 path (HAM7 layout), hoping to make the job of aligning that path to a diode on SQZT7 easier.  The beam was pitched up by pitching B:M4 when we aligned this path through the viewport simulator, because we were attempting to align the beam to the center of the viewport.   After the discussion in 60070 we realize that this beam will need to pass through the viewport below the center, and should not be pitched up but left parallel to the ISI for the ZM4/5 path. 

Locking VIP suspension

We had previously locked the OPO suspension down without taking much care to not change the pointing, but decided to lock it down while watching the osems this time before we set B:M4 to level the ZM4/5 beam with the ISI.  Our prevous expirience in HAM6 was that unlocking and relocking the VIP suspension didn't have much impact on the alignment, but we decided to confirm that was true and then leave the suspension locked for the next several steps in HAM7. 

VIP floating osem inputs:

H1:SUS-OPO_M1_OSEMINF_H1_INMON 9072.38125
H1:SUS-OPO_M1_OSEMINF_H2_INMON 11200.222607421874
H1:SUS-OPO_M1_OSEMINF_H3_INMON 11706.123828125
H1:SUS-OPO_M1_OSEMINF_V1_INMON 13617.775830078124
H1:SUS-OPO_M1_OSEMINF_V2_INMON 13690.507177734375
H1:SUS-OPO_M1_OSEMINF_V3_INMON 11140.362060546875

VIP locked with all three lockers down, screws tightened for corner 1 corner 3:

H1:SUS-OPO_M1_OSEMINF_H1_INMON 8360.248560855267
H1:SUS-OPO_M1_OSEMINF_H2_INMON 12107.490285773027
H1:SUS-OPO_M1_OSEMINF_H3_INMON 7730.751747532895
H1:SUS-OPO_M1_OSEMINF_V1_INMON 16896.670127467103
H1:SUS-OPO_M1_OSEMINF_V2_INMON 19016.05931332237
H1:SUS-OPO_M1_OSEMINF_V3_INMON 17632.022820723683

VOPO oven

 

Comments related to this report
keita.kawabe@LIGO.ORG - 17:34, Tuesday 05 October 2021 (60148)
Link

Green fiber swap

Jim, Camilla and I swapped the pump and FC sensing fibers (both green) at the collimator end because we wanted to use a better fiber for the pump. We didn't bother to swap the feedthroughs as that's more risk to fibers. We swapped the in-air fibers at the feedthrough to match the in-chamber ones. As a result, HAM7 fiber flange layout as of now is this:

Position Fiber
D6F1 Green FC (Filter cavity sensing), bad
D6F2 Green OPO (Pump), good
D6F3 IR

I added a red-lined document to https://dcc.ligo.org/D1900116-v11. Jim rerouted the fibers after the swap.

We didn't clean the fibers in chamber. We did clean fibers and feedthroughs at the air-side.

We might consider swapping the bad fiber with a new one if that is delivered reasonably quickly.

After this, Georgia was able to quickly realign the pump in chamber.

sheila.dwyer@LIGO.ORG - 10:35, Wednesday 06 October 2021 (60156)
Link

After the fiber swap Georgia quickly realinged the pump to the OPO. 

On the PDA100A on the 40dB setting in the OPO trans path on SQZT7, (which Georgia moved so that it isn't blocking the homodyne beam) we measured 2.6V for the 00 mode peak, the second order modes are about 20% of the 00 mode, and each of the sidebands are also about 21% of the 00 peak.  The misalignment peak is about 7% of the 00 peak. 

We measured 74uW on the OPO refl diode, and noticed while checking this that the beam is now clipped on the top periscope mirror.  We did look at the PDH signal, which is about 100mV pp.  We will fix the clipping before we double check the phasing and try to lock.