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Entry  Tue Oct 18 15:20:03 2011, kiwamu, Summary, IOO, RFAM plan 
    Reply  Thu Oct 27 18:00:38 2011, kiwamu, Summary, LSC, Offsets in LSC signals due to the RFAMs : Optickle simulation ratio.pngupper.pngPRCL_200.pngMICH_200.pngSRCL_200.png
Message ID: 5686     Entry time: Tue Oct 18 15:20:03 2011     Reply to this: 5747
Author: kiwamu 
Type: Summary 
Category: IOO 
Subject: RFAM plan 

[Suresh / Koji / Rana / Kiwamu]

Last night we had a discussion about what we do for the RFAM issue. Here is the plan.

 

(PLAN)

  1. Build and install an RFAM monitor (a.k.a StochMon ) with a combination of a power splitter, band-pass-filters and Wenzel RMS detectors.

       => Some ordering has started (#5682). The Wenzel RMS detectors are already in hands.

  2. Install a temperature sensor on the EOM. And if possible install it with a new EOM resonant box.

      => make a wheatstone bridge circuit, whose voltage is modulated with a local oscillator at 100 Hz or so.

  3. Install a broadband RFPD to monitor the RFAMs and connect it to the StochMon network.

      => Koji's broadband PD or a commercial RFPD (e.g. Newfocus 1811 or similar)

  4. Measure the response of the amount of the RFAM versus the temperature of the EO crystal.

      => to see whether if stabilizing the temperature stabilizes the RFAM or not.

  5.  Measure the long-term behavior of the RFAM.

      => to estimate the worst amount of the RFAM and the time scale of its variation

  6. Decide which physical quantity we will stabilize, the temperature or the amount of the RFAM.

  7. Implement a digital servo to stabilize the RFAMs by feeding signals back to a heater

     => we need to install a heater on the EOM.

  8. In parallel to those actions, figure out how much offsets each LSC error signal will have due to the current amount of the RFAMs.

    => Optickle simulations.

  9. Set some criteria on the allowed amount of the RFAMs

    => With some given offsets in the LSC error signal, we investigate what kind of (bad) effects we will have.

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