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Entry  Fri Aug 3 19:02:11 2018, gautam, Update, ASS, X arm ASS recovery 
    Reply  Tue Aug 14 00:50:32 2018, gautam, Update, ASS, X arm ASS still not quite right? POXPOY.pngIMG_7108.JPG
Message ID: 14161     Entry time: Tue Aug 14 00:50:32 2018     In reply to: 14132
Author: gautam 
Type: Update 
Category: ASS 
Subject: X arm ASS still not quite right? 

While working on the single arm alignment, I noticed that today, i was able to get the X arm transmission back to ~1.22, and the GTRX to 0.52. These are closer to the values I remember from prior to the vent. Running the dither alignment promptly degrades both the green and IR transmissions. Since the pianosa SL7 upgrade, I can't use the sensoray to capture images, but to me, the spot looks a little off-center in Yaw on ETMX in this configuration, I've tried to show this in the phone grab (Atm #2). Maybe indicative of clipping somewhere upstream of ITMX?

Anyways, I'm pushing onwards for now, something to check out in the daytime.

Quote:

[koji, gautam]

After I effected the series resistance change for ETMX, the X arm ASS didn't work (i.e. IR transmission would degrade if the servo was run). Today, we succeeded in recovering a functional ASS servo yes.

We then tried to maximize GTRX using the PZT mirrors, but were only successful in reaching a maximum of 0.41. The value I remember from before the vent was 0.5, and indeed, with the IR alignment not quite optimized before we began this work, I saw GTRX of 0.48. But the IR dither servo signals indicate that the cavity axis may have shifted (spot position on the ITM, which is uncontrolled, seems to have drifred significantly, the Pitch signal doesn't stay on the StripTool scale anymore). So we may have to double check that the transmitted beam isn't falling off the GTRX DC PD.

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