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Entry  Fri Jul 30 13:38:56 2010, Dmass, Laser, Doubling, Mode Matching for Ovens OvenMM.pdf
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          Reply  Wed Aug 4 17:21:56 2010, Alastair, Laser, Doubling, Mode Matching for Ovens 
          Reply  Sat Aug 7 19:04:07 2010, Dmass, Laser, Doubling, Mode Matching for Ovens 
Message ID: 913     Entry time: Sat Aug 7 19:04:07 2010     In reply to: 900
Author: Dmass 
Type: Laser 
Category: Doubling 
Subject: Mode Matching for Ovens 

Here is a semi complete plan of my "what next" when I get back:

  1. Finish Arm Mode Matching
    1. Relock PMC / spend a couple minutes fidding with gain and looking at ERR on a scope
    2. Tweak mirrors to reoptimize power output on a power meter
    3. Quick check of power in PMC input / refl / trans to see if loss is insane
    4. Block each arm and add a lens after the oven to make the spot (~500 um diam?) large at stolen ISS PDs
    5. Check that the size is still fine @ the green PDs
    6. Put Green PDs into my electronics box (that's where their transimpedance amps are)
    7. Align and check contrast defect. Pic of PDs on scope with PZT sweeping - verify
  2. Get more Green PD batteries just in case (maybe before 1 if I have to order)
  3. Rotate the ovens so the crystal axis is as close as I can make it to the optic axis. Find the phase matching temperature maximum crudely
  4. Move the ovens around along the axis to try to get a maximum power
  5. Get a good measurement of the phase matching curve: Block each arm and get the phase matching curve for each oven (~60 second time constant, so ~1-2 hour meas to get it well). Note this is only good for one angle, so every time I touch (re: twist) the oven, this phase matching width / temperature can change - I should be able to estimate this effect with less than a couple hours thinking). Note that this will be my theta/T calibration, and really needs to be a 5-10 percent number or so.
  6. Balance PDs (May have to replace op amps if any are bad at this point)
    1. Sweep the PZT of the MZ
    2. Look at Lissajous figure of Diff 1 vs Diff 2 with all 4 PD inputs connected, balance this with the pots inside the PD box
    3. Look at the Lissajous, make its crossing zero (so we can have Green Diff and IR Diff both be ~ zero)
    4. Get Min / Max of Lissajous for calibration
  7. Attempt to lock the Mach Zehnder (by first turning down the MZ gain, then increasing once lock is acquired)
    1. Post calibrated phase noise spectum to the elog
    2. ASSESS AT THIS POINT WHETHER TO DO STEPS 9 AND 10 OR JUST 9...OR EVEN JUST USING THE POOR PRECISION THERMOMETERS TO ESTIMATE PHASE NOISE FROM TEMPERATURE
  8. Calibrate the PZT Drive signal?
    1. Make a breakout cable from the front of the HV PZT Drive Box (On the PZT VMON output - D9 to BNC)
    2. Sweep PZT, look at ERR (phase noise difference, already calibrated)
    3. Have calibrated control signal now!
  9. Add thermometer to ADC
    1. Use the silver epoxy to directly glue temperature sensors from Frank to the oven
    2. Power them with an AD587 in series with some resistor (not really a current source, but it's fine)
    3. Calibrate thermometer using temperature sensor already on oven (RTDs), readout by the Newport 3040 temperature controller
    4. Add to ADC as calibrated readout of each oven temperature
  10. Subtract!?!?
    1. Look at coherence between temperature and phase noise in green (I expect there to be some)
    2. Do frequency domain subtraction of Temperature from Green Phase Noise with the scripts which I already wrote (this is easy)
    3. Compare the suppressed level of Green phase noise with the servod IR phase noise
    4. Compare suppression level to known noise floor of experiment. Figure out how best to present this plot
  11. ????????
  12. Profit.
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