40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Wed Jul 23 22:34:07 2008, Yoichi, Update, LSC, Arm cavity g-factor measurement 
    Reply  Thu Jul 24 01:27:00 2008, Koji, Update, LSC, Arm cavity g-factor measurement 
       Reply  Thu Jul 24 02:57:26 2008, rob, Update, LSC, Arm cavity g-factor measurement 
          Reply  Thu Jul 24 08:09:26 2008, Yoichi, Update, LSC, Arm cavity g-factor measurement 
Message ID: 731     Entry time: Thu Jul 24 02:57:26 2008     In reply to: 730     Reply to this: 733
Author: rob 
Type: Update 
Category: LSC 
Subject: Arm cavity g-factor measurement 

Quote:

So, now I feel that the method for the TEM01 quest should be reconsidered.

If we have any unbalanced resonance for the phase modulation sidebands, the offset of the error signal is to be observed even with the carrier exactly at the resonance. We don't need to shake or move the cavity mirrors.

Presence of the MC makes the things more complicated. Changing the frequency of the modulation that should go throgh the MC is a bit tricky as the detuning produces FM-AM conversion. i.e. The beam incident on the arm cavity may be not only phase modulated but also amplitude modulated. This makes the measurement of the offset described above difficult.

The setup of the abs length measurement (FSR measurement) will be easily used for the measurement of the transverse mode spacings. But it needs some more time to be realized.


We should be able to see 166MHz sideband resonances using the double demodulated photodetectors. With these, the 33MHz sidebands will be acting as LO when the 166MHz sideband (or mode) resonates. Some modeling may be necessary to determine if the SNR will be good enough to make this worthwhile, however.
ELOG V3.1.3-