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Entry  Thu Feb 6 16:41:31 2014, ericq, Update, General, In-Vac Alignment 
    Reply  Fri Feb 7 12:43:12 2014, ericq, Update, General, In-Vac Alignment 
       Reply  Fri Feb 7 13:00:52 2014, Jenne, Update, General, In-Vac Alignment 
          Reply  Fri Feb 7 13:30:22 2014, Gabriele, Update, General, In-Vac Alignment 
          Reply  Fri Feb 7 13:30:25 2014, ericq, Update, General, In-Vac Alignment 
Message ID: 9609     Entry time: Fri Feb 7 12:43:12 2014     In reply to: 9608     Reply to this: 9610
Author: ericq 
Type: Update 
Category: General 
Subject: In-Vac Alignment 

[ericq]

PRC Locked on Sidebands

Jenne reminded me that if we change a cavity, phases can change... So, first, I locked the PRC on the carrier, and then gave it MICH and PRCL excitations to optimize the AS55 and REFL55 phase rotation angles by looking at the excitation demodulated outputs of the unused quadrature (i.e. we want all of MICH to be in AS55 Q, so I rotated the phase until C1:CAL-SENSMAT_MICH_AS55_I_I_OUTPUT was zero on average).

This resulted in:

  • AS55: 7 -> -5.5
  • REFL55: 73 -> 86.9

I then used the same settings as in ELOG 9554, except I used -1s instead of +1s for the POP110I trigger matrix elements. (I'm not sure why this is different, but I noticed that the PRC would lock on carrier with positive entries here, so I figured we wanted the peaks with opposite sign).

So far, it seems more stable than when we were doing the demodulation phase measurements, it's been locked for >15 minutes without me having to tweak the gains or the alignment from the carrier locked case.

ELOG V3.1.3-