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Entry  Wed Nov 4 16:49:32 2009, Alberto, Update, LSC, Arm Cavity Finesse Measurement DSC_0952.JPG
    Reply  Wed Nov 4 18:35:19 2009, Alberto, Update, LSC, Arm Cavity Finesse Measurement 
       Reply  Wed Nov 4 21:46:18 2009, Alberto, Update, LSC, Arm Cavity Finesse Measurement 
Message ID: 2176     Entry time: Wed Nov 4 21:46:18 2009     In reply to: 2175
Author: Alberto 
Type: Update 
Category: LSC 
Subject: Arm Cavity Finesse Measurement 



I'm going to work on the X arm to measure the arm cavity finesse.

The idea is to measure the cavity transfer function to estimate the frequency of its cavity pole. That should be a more accurate measurement than that based on the cavity decay time.

I'm starting now and I'm going to inject a swept sine excitation on the OMC_ISS_EXC input cable laying on the floor nearby the AP table (see pic).


In orderf to do that I disconnected the cable from the OMC breakout box laying on the floor. I'm going to plug the cable back in as soon as I'm done.

 Since I need to measure the transfer function between TRX and MC_TRANS_DC I picked off the beam going to RFAM PD to send it to a PDA255 photodiode (cannibalized from the AbsL's PLL) which I installed on the PSL table.

I centerd the beam on the PD and I was able to see the injected signal.

I think I'm ready to measure the transfer function.

Except for the RFAM PD everything is as before.

I'm gonna go grab dinner and I should be back to keep working on that in about one hour.

 Back from dinner. Taking measurements.

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