Sheila, Jeff B

I used the new remote desktop tonight for the first time, it's really great.  I was able to watch the squeezer channels while Jeff adjusted the current on the floor, the latency is low enough that I could see exactly what was going on. Thank you CDS!

Keita and Jeff got in touch because there are some errors with the squeezer.  The SHG power stabilization was railed, which is actually happening a lot.  This is something that we need to make more reliable somehow, but it doesn't really have much of an impact on the sensitivity so it is OK to just keep observing like this.  

The reason that this servo keeps railing is that the squeezer was unimpressed by my efforts to reduce backscatter on Tuesday 49237 and the mode hopping is getting pretty bad.  The attached screenshot shows that we have temporarily fixed this several times over the last few months by adjusting the laser current, but after a few weeks the mode hopping comes back.  Tonight Jeff and I took H1 out of observing for a few minutes, turned off the squeezer by requesting SQUEEZER_READY_IFO from the SQZ_MANAGER guardian, and while I watched the laser diode current and the slow temperature feedback from the FSS (H1:SQZ-LASER_HEAD_CRYSTALFREQUENCY) Jeff adjusted the laser current knob.  As he lowered the current, the temperature control signal became more negative.  To avoid hitting the rail, he made small adjustments to the temperature knob on the laser controller while I watched the control signal come back to zero.  

I think that we probably didn't make a large enough change to the current, we started with the set current at 2.107A, now it is around 1.98 A.  We decided to go back to observing and wait a half hour to see if he green power becomes any more stable; it did not.  We might need to go as low as 1.9 A this way before we see a real improvement. By the time we had waited a half hour, we were back in triple coincidence and decided not to drop out to try to fix this now.  

It might be that the long term solution to this problem is to swap the squeezer laser soon, probably once both Daniel and I are back on site.  In the meantime there are probably 3 options:1)  leave it alone as long as the squeezer keeps locking, 2) step the laser current down to about 1.9A, while trying to step the temperature up to keep the beatnote as Jeff and I did tonight 3) make a full search for a mode hop free region as described in 48537