Reports until 21:39, Thursday 29 January 2026
H1 SQZ
sheila.dwyer@LIGO.ORG - posted 21:39, Thursday 29 January 2026 - last comment - 12:53, Friday 30 January 2026(88966)
HAM7 work today

This morning Rahul took a transfer function of the OPO suspension and found that adding a zip tie to the new connector didn't help the transfer function, which is still similar to 88921.  We decided with Jeff to live with this as it is, and we spent the rest of the day working on resolving the clipping through the VIP introduced by alignment shifts that happened as we were addressing the cables.  

We moved A:M3 enough that we no longer see evidence of clipping in the SFI1 both passes, we measure 0.96mW out of the OPO and about the same power in transmission from SFI1 on the the return from the filter cavity.  We then saw that the beam was clipping in SFI2, and adjusted B:M1 until we were measuring about 0.88- 0.9mW after SFI2, but we had clipping on the aperture attached to B:L2.  We had nearly lost the beam to SQZT7 by this time, so we spent some time restoring that by adjusting pitch on B:M3 and yaw on B:M4 (with the platform unlocked it is difficult to adjust pitch on the tough pitch knob for B:M4).  This brought us to a point where we can see 0.7 counts on the OPO IR PD on SQZT7.  

At the end of the day, we were still seeing loss at B:L2, where the beam was only about 0.82mW.  We also need to restore the alignment onto the irises on SQZT7.  

We will need to readjust the alignment onto the filter cavity QPDs before we close the chamber. 

 

Comments related to this report
rahul.kumar@LIGO.ORG - 12:53, Friday 30 January 2026 (88971)SQZ

Power measured this morning in HAM7,

0.95mW out of OPO

0.92mW out of SFI2

0.83mW ou of B L2

0.83mW on table (and looks centered on both the iris on the able).

We are somehow clipping on the lens (placed after the SFI2), we might move it mechanically since adjusting the beam using mirror is not helping.