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Entry  Mon Mar 22 15:01:24 2010, Dmass, Laser, ISS, ISS Spectra ISSILandOL.pdfGreenPDsBudget.pngIRPDsBudget.pngPDSubtracAll.pdf
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             Reply  Thu Mar 25 14:16:32 2010, Dmass, Laser, ISS, MZ Spectra! rawdata.zipLockedPhaseNoise.pdf
Message ID: 710     Entry time: Thu Mar 25 14:16:32 2010     In reply to: 709
Author: Dmass 
Type: Laser 
Category: ISS 
Subject: MZ Spectra! 

This is the phase noise of the locked Mach Zehnder.

There is no subtraction, but since it is locked, any actual phase we could subtract should be supressed by the loop feeding back to the MZ PZT (single pole @ 1 Hz with a UGF somewhere around 20)

I am plotting the difference of the green PDs, and the difference of the IR PDs (they are in loop for the Mach Zehnder)

  • Green: [min,max] = [-4.7,7.2]
  • IR: [min,max] = [-8,8.5]   
  • Green DC = -1.36
  • IR DC = 2.84

Calibration is:

dV/dthet = Vpp/2*sqrt(1-(2V/Vpp)^2)

Notes:

  • I think we didn't realign the Mach Zehnder PZT after connecting the driver, which tosses 150V offset onto the PZT - I don't know if this could effect our contrast (if its a pointing change)
  • I think the large offset in green means that we have a PD imbalance, I have to think about this. If this is the case, I'll toss some balancing amplifier with a POT after the transimpedance amps to make the signals equal amplitude.
  • We are operating off fringe for both Green and IR, the point is somewhat abritrarily chosen for now, though I can conceivably make a more intelligent decision about this later.
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