Jennie, Jenne, Vicky
As part of a larger suite of optimisations today, the interferometer was taken out of observing and we tried to optimise the H1:LSC-SRCL1_OFFSET to remove the SRC detuning (optical spring).
I took these measurements yesterday, and as a result Jenne agreed that the higher we could push the OFFSET to negative side, the better.
But, that this is not possible for stable operation as it will not give us enough control range before the photodiode readout saturates (at 32000 counts).
I noted yesterday that our largest offset gave us a huge reading on the POP REFL 45 PD ( H1:LSC-POP_A_RF45_I_INMON ) ~ 27 000 cts.
Therefore we will aim to push no further than 22 000 counts for either H1:LSC-POP_A_RF45_I_INMON (in phase PD readout) or H1:LSC-POP_A_RF45_Q_INMON (quadrature phase PD readout).
| SRCL1 OFFSET | DARM Inj Start Time | PCAL > DARM Inj Start Time | DARM Measurement Folder | PCAL > DARM Measurement Folder | Data Folder | Figure Folder |
|---|---|---|---|---|---|---|
| -200 | 1367177285 | 1367177493 | /ligo/gitcommon/noise_recorder/data/darm_noise/202305031227/darm_noise_srcl_src1_-200cts_DARM_offset_tuning-6_50_6_50_Hz_gps_start_1367177285.hdf5 |
/ligo/gitcommon/noise_recorder/data/darm_noise/202305031231/darm_noise_srcl_src1_-200cts_DARM_offset_tuning-6_50_6_50_Hz_gps_start_1367177493.hdf5 |
/ligo/gitcommon/noise_recorder/data/darm_noise/202305031227/ | /ligo/gitcommon/noise_recorder/figures/darm_noise/202305031227/ |
| -165 | 1367178977 | 1367179163 | /ligo/gitcommon/noise_recorder/data/darm_noise/202305031255/darm_noise_srcl_src1_-165cts_DARM_offset_tuning-6_50_6_50_Hz_gps_start_1367178977.hdf5 | /ligo/gitcommon/noise_recorder/data/darm_noise/202305031259/pcaly_srcl_src1_-165cts_DARM_offset_tuning-6_50_6_50_Hz_gps_start_1367179163.hdf5 |
/ligo/gitcommon/noise_recorder/data/darm_noise/202305031255/ | /ligo/gitcommon/noise_recorder/figures/darm_noise/202305031255/ |
Changing the SRCL1 offset to -200 gives us a reading on the photodiode of around -22761 cts for the in phase readout and -5499 cts for the quadrature phase readout.
The first pdf attached shows the results for the -200 count SRCL1 offset, and the second one for the previously used SRCL1 offset value of -165 counts.
It can be seen from the ssensing function plot (last image in both pdfs) that the -200 count measurement appears flatter at low frequency.
After this point I handed over to Vicky to optimise squeezing.
The following measurements were taken after the DARM offset was changed from 20mA to 40mA. And the same set of graphs is attached below for each.
| SRCL1 OFFSET | DARM Inj Start Time | PCAL > DARM Inj Start Time | DARM Measurement Folder | PCAL > DARM Measurement Folder | Data Folder | Figure Folder |
|---|---|---|---|---|---|---|
| -200 | 1367180967 | 1367181204 | /ligo/gitcommon/noise_recorder/data/darm_noise/202305031329/darm_noise_srcl_src1_-200cts_higher_DARM_offset_-6_50_6_50_Hz_gps_start_1367180967.hdf5 |
/ligo/gitcommon/noise_recorder/data/darm_noise/202305031333/pcaly_srcl_src1_-200cts_higher_DARM_offset_-6_50_6_50_Hz_gps_start_1367181204.hdf5 |
/ligo/gitcommon/noise_recorder/data/darm_noise/202305031329/ | /ligo/gitcommon/noise_recorder/figures/darm_noise/202305031329/ |
| -165 | 1367181539 | 1367181751 | /ligo/gitcommon/noise_recorder/data/darm_noise/202305031338/darm_noise_srcl_src1_-165cts_Higher_DARM_offset_-6_50_6_50_Hz_gps_start_1367181539.hdf5 | /ligo/gitcommon/noise_recorder/data/darm_noise/202305031342/pcaly_srcl_src1_-165cts_Higher_DARM_offset_-6_50_6_50_Hz_gps_start_1367181751.hdf5 |
/ligo/gitcommon/noise_recorder/data/darm_noise/202305031338/ | /ligo/gitcommon/noise_recorder/figures/darm_noise/202305031338 |
SRCL1 offset is now -200 counts.
