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Entry  Thu Mar 17 16:50:53 2022, Paco, Update, BHD, XARM AUX alignment 
    Reply  Fri Mar 18 17:15:19 2022, Paco, Update, BHD, XARM AUX alignment cont. Screen_Shot_2022-03-18_at_4.09.38_PM.png
       Reply  Mon Mar 21 18:00:05 2022, Ian MacMillan, Update, BHD, XARM AUX alignment cont. PXL_20220322_015247138.jpg
Message ID: 16739     Entry time: Mon Mar 21 18:00:05 2022     In reply to: 16735
Author: Ian MacMillan 
Type: Update 
Category: BHD 
Subject: XARM AUX alignment cont. 

[Ian, Paco]

Continuing with the previous alignment that we stoped on friday, we re set up my heavily cleaned iPhone on FaceTime. The Phone alowed us to see the laser on the ITMX and center it on that optic.

  • We increased the trigger level for the watchdog on the optics.
  • Green beam was centered on th ITMX.
  • aligned the green laser: prompt reflection off of the ETMX to maximize the signal on the reflection PD
  • Went back to ITMX chamber, looked for the beam in the tube to see if the laser was hitting the beam tube off of the ITMX. From there we comunicated how to adjust the beam to move the beam towards the ETMX.
  • On the ETMX the reflection PD signal was measured and the ITMX was adjusted using CDS until ripples/"flashes" were seen in the reflection PD channel (C1:ALS-X_REFL_DC_OUT_DQ).
  • Once we saw flashing we tried to minimize the reflection pd signal using only ITMX alignment slider so that all the light was being held in the cavity.
  • Once we had this going the PDH lock engaged the higher order mode that we were seeing.
  • We removed the phone setup and closed up the ITMX chamber.
  • From here we moved to the control room and continude to adjust the ITMX and ETMX to see if we could lock to a lower order mode.
    • This proved unsuccessful so we will resume by trying to replicate the ASS action manually (with M1 - M2 PZT sliders and the REFL PD)
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