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Entry  Wed May 19 22:40:19 2010, Dmass, Electronics, Doubling, Oddness with my box Plotted17.pdfMZVoltsLowAvg.pdf
    Reply  Wed May 19 23:33:18 2010, Dmass, Electronics, Doubling, Oddness with my box 
       Reply  Thu May 20 00:41:51 2010, Koji, Electronics, Doubling, Oddness with my box 
          Reply  Thu May 20 21:43:01 2010, Dmass, Electronics, Doubling, Oddness with my box 
             Reply  Fri May 21 17:42:29 2010, Dmass, Electronics, Doubling, The Box Itself MZ_Electronics.pdfMZBoxGoodPic.png
                Reply  Fri Jun 4 13:46:26 2010, Dmass, Electronics, Doubling, The Box Itself 
Message ID: 783     Entry time: Thu May 20 21:43:01 2010     In reply to: 782     Reply to this: 784
Author: Dmass 
Type: Electronics 
Category: Doubling 
Subject: Oddness with my box 

Yes it does happen if I touch the BNC shells to the box ground.

  • I found that it was a ground loop from using the same power supply on both the ISS PD box and my box, and using the ground from that power supply to ground both boxes.
    • I did not, however see a forest of the line harmonics. I saw a huge white noise, and I am near certain that it was noise entering into my ground and touching the "+" input of my transimpedance resistors.
    • When I put a 50 Ohm terminator on the transimpedance amplifier's "-" input (100k Trans Res), I amplified the heck out of the noise at the +, which allowed me to see this crazy behavior. Fortuitous?
  • I put them on separate power supplies and the dark noise level now is not displaying "THE EFFECT"
  • I measured a phase noise spectrum open and closed loop, and saw the same behavior as before...
    • I see no suppression of green phase noise when I close the loop on IR
    • I talked with Vladimir for a while about this, and think I might have a handle on how locking the IR might not suppress the green if thermoelastic and thermorefractive noise in the crystal drives the phase noise at all.
    • I will try making the temperature more unstable to see if I see any effect (go closer to open loop)
    • I may try to add some sort of shielding around the ovens to keep air currents from beating on the copper block
    • One oven has "bad wiring" of some sort and I see ~15 mK rms fluctuations IN LOOP over a couple seconds. I will probably want to rewire this
    • I need to think more on what quasi phase matching means, and if the phase mismatch in the quasi phase matched case (the argument of the sinc^2) is just the phase difference between the IR and green field leaving the crystal (modulo pi)
  • I shall also add some pics and schematics of the circuitry for later date debugging purposes
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