OMC Scan with SQZ beam yesterday

Naoki, Vicky, Jennie W

 

Naoki followed the directions in to set up the SQZ beam OMC scan.

We had a problem with the DC centering loops. After we switched them on they saturated the OM1 and OM2 suspensions.

We got around this by switching each of the 4 degrees of freedom on first - ie. DC3 Y, DC3 P, DC4 Y, DC4 P.

Then we engaged OMC ASC and this seemed to work ok.

When we tried to manually lock the OMC length loop we had problems as when we switched the gain of 1 on it would lose lock, even when on a TM00 mode of the expected height (0.6mA on DCPD_SUM).

Vicky got around this this using a lower gain and not engaging the BOOST filter in the servo filter bank.

Then she had to touch up the alignment in lock with OM3.

locked quiet time 1397329970 GPS 1 min:

OMC-REFL_A_LF_OUT16 = 0.0930255 mW

OMC-DCPD_SUM_OUTPUT = 0.652156 mA

 

unlocked quiet time 1397330106 GPS 1 minute:

OMC-REFL_A_LF_OUT16  = 1.04825 mW

OMC-DCPD_SUM_OUTPUT = -0.00133668 mA

 

dark measurement 1397330625 GPS 1 minute:

OMC-REFL_A_LF_OUT16  = -0.0133655 mW

OMC-DCPD_SUM_OUTPUT = -0.00133668 mA

 

I noticed after I took the dark measurement that OM1 and 2 were staurating again and need to clear history twice on OM1 to remove this.

Reverted OM1 and 2, 3 OMC sliders at 8:33 am (local time) on the 16th April.

Data is saved as REf 3, 4 and 5 in /ligo/home/jennifer.wright/Documents/OMC_scan/2024_04_16_OMC_scan.xml. Where 3 is the scan channel OMC-DCPD_SUM_OUT_DQ on the bottom right plot, 4 is the PZT excitation channel OMC-PZT2_EXC on the bottom left plot, and 5 is the monitor of the actual PZT output voltage OMC-PZT2_MON_DC_OUT_DQ on the top right plot.