Reports until 11:26, Tuesday 03 July 2018
H1 AOS (SUS)
jason.oberling@LIGO.ORG - posted 11:26, Tuesday 03 July 2018 - last comment - 10:58, Thursday 12 July 2018(42748)
ETMy Optical Lever Switched Back to Original Laser

This morning, in response to FRS 10964 (alog 42658), I switched the ETMy OpLev laser back to the original diode laser.  To aid in diagnosing the abnormally high electronics noise seen in this OpLev, I switched the gains back to their original settings in a staggered fashion:

After switching back to the original laser, I turned the 3rd whitening filter stage OFF and deactivated the 3rd stage of digital compensation; this change was accepted in SDF.  Not knowing the state of ETMy alignment, I did not re-center the OpLev; this can be done at a later date either when necessary or when a good alignment for ETMy is acheived.

Edit to add: The Output Configuration Switch (OCS) is now set as shown in T150556, which is the ETMy setting used for the diode laser.
Edit #2: Added the time of the laser switch.
Comments related to this report
jeffrey.kissel@LIGO.ORG - 15:43, Tuesday 03 July 2018 (42756)ISC, SUS
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J. Kissel

H1 SUS ETMY Optical lever restored to it's previous glory! I consider this a close on FRS Ticket 10964. 

Check out attached ASD comparison with other optical levers after driving optics such that each lever's laser reflection off the test masses is centered on each lever's QPD.

Now ETMX is the poor performer ... it looks like its SUM is rather low compared to the other levers...
   - Cyan reference trace is from when I was made aware that the former ETMY optical lever that had a temporary laser was performing poorly.
   - Magenta ETMX trace is from the same time.
   - All other traces are from the now time. 
Because this entry serves to convey that ETMY is now good again, it's current trace is in bold blue.

ETMX yaw appears to not have changed since the reference (and is still worse than others), while Pitch seems to have gotten worse. This may be physical motion related to the problems Jim has found (see LHO aLOG 42711), or it may (again) be the low laser power detected at the QPD.

The template for these ASDs lives here:
/ligo/home/jeffrey.kissel/Templates/DTT/H1_OpticalLevers_Performance_ASDs.xml
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edmond.merilh@LIGO.ORG - 10:58, Thursday 12 July 2018 (42873)
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So, I went down and fired the HeNe and switched all the cabling to the "Board 2" side of the whitening chassis just for comparative analysis. I left the filtering as is and simply set the BIO to various gain settings (21dB, 18dB, 15dB, and 9dB / OL damping OFF) in an effort to rule out any excessive noise that may have been originating in the circuitry being used. My findings were that the ASDs looked fairly identical. After a quick analysis, with Jenne's help to interpret, it seems that from .6Hz - broadband is dominated by electronics noise and doesn't show any improvement even at very low gain (which isn't enough light on the QPD anyway). Perhaps the 3mW version would make a better showing?

All that being said, there's still the issue of 60Hz noise with a 2Hz sideband that Robert observed...

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