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  Mon Nov 26 23:45:52 2012, Ayaka, Update, IOO, Tuning MC_L POYerr_MCL.jpgMCL-MCFxover.jpgMCL-MCFxover2.jpg121126.tar.gz
    Reply  Tue Nov 27 00:45:20 2012, jamie, Update, IOO, MC_L and laser frequency noise spectra laser_noise.pdfMCL_noise.pdf
Message ID: 7750     Entry time: Tue Nov 27 00:45:20 2012     In reply to: 7748
Author: jamie 
Type: Update 
Category: IOO 
Subject: MC_L and laser frequency noise spectra 

I grabbed the a plot of the iLIGO PSL frequency noise spectrum from the Rana manifesto:

laser_noise.pdf

Rana's contention is that this spectrum (red trace) is roughly the same as for our NPRO.

From the jenne/mevans/pepper/rana paper Active noise cancellation in a suspended interferometer I pulled a plot of the calibrated MC_L noise spectrum:

MCL_noise.pdf

The green line on this plot is a rough estimate of where the above laser frequency noise would fall on this plot.  The conversion is:

    L / f  =  10 m / 2.8e14 Hz = 3.5e-14 m/Hz

which at 10 Hz is roughly 1.5e-11 m.  This puts the crossover somewhere between 1 and 10 Hz.

ELOG V3.1.3-