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Entry  Sat May 5 01:24:07 2012, Den, Update, PSL, PMC whitening.jpgmcf_v.png
    Reply  Sat May 5 09:13:02 2012, Koji, Update, PSL, PMC 
       Reply  Sat May 5 10:20:21 2012, Den, Update, PSL, PMC 
          Reply  Sat May 5 12:23:38 2012, Koji, Update, PSL, PMC 
Message ID: 6604     Entry time: Sat May 5 01:24:07 2012     Reply to this: 6605
Author: Den 
Type: Update 
Category: PSL 
Subject: PMC 

I was interested what whitening filter do we have between MC servo and ADC. The shape is in the figure below, SR provided 1 V white noise. Before the whitening filter MC_F is measured in Volts with SR and ADC (for ADC the shape is calculated using the whitening filter form):

whitening.jpg     mcf_v.png

I also wondered if FSS or PZT servo can add noise to the mode cleaner length signal and what is their gain. It should be big, as the laser's calibration is ~1 MHz/V => to account for seismic noise of 10^-6 m at 1 Hz, the voltage given to the laser should be ~ 1 V. And it is indeed the case. The gain is ~1000. I measured the coherence between MC_F and the laser fast input. It is 1 in the range measured (0.05 - 100 Hz). FSS and PZT do not add significant noise.

Unfortunately, after the measurement when I unplugged BNS connector from the laser, I misaligned PMC. For several hours I adjusted the mirrors but could not significantly improve transmitted signal. I'll return to this issue tomorrow.

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