Reports until 15:06, Thursday 03 October 2024
H1 SQZ
sheila.dwyer@LIGO.ORG - posted 15:06, Thursday 03 October 2024 (80450)
OPO PZT voltage changes squeezing

Camilla and I ran SQZ_ALIGNMENT and SCAN_SQZ_ANG with the offset on PZT2 (we are using H1:SQZ-CLF_SERVO_SLOWOUTOFS) set to 0, while the nominal value is 10.  We then went to no squeezing and set the offset back to it's nominal value, and saw reduced squeezing when we reinjected squeezing.  We could recover the better squeezing level by slowly stepping this offset back to 0V.  We think that this could be because the PZT setting changes the alignment of the OPO, and the squeezed beam coming out of it.  (which also changes the squeezing angle). 

A similar effect was seen with PZT1 in 80396 and 78529.  It would be interesting another time to try changing this offset and seeing if we can recover squeezing by readjusting alignment and squeezing angle.