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Fri Jul 30 13:38:56 2010, Dmass, Laser, Doubling, Mode Matching for Ovens
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Tue Aug 3 21:43:40 2010, Dmass, Laser, Doubling, Mode Matching for Ovens
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Tue Aug 3 23:15:14 2010, Dmass, Laser, Doubling, Mode Matching for Ovens
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Wed Aug 4 17:21:56 2010, Alastair, Laser, Doubling, Mode Matching for Ovens
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Sat Aug 7 19:04:07 2010, Dmass, Laser, Doubling, Mode Matching for Ovens
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Message ID: 913
Entry time: Sat Aug 7 19:04:07 2010
In reply to: 900
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Author: |
Dmass |
Type: |
Laser |
Category: |
Doubling |
Subject: |
Mode Matching for Ovens |
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Here is a semi complete plan of my "what next" when I get back:
- Finish Arm Mode Matching
- Relock PMC / spend a couple minutes fidding with gain and looking at ERR on a scope
- Tweak mirrors to reoptimize power output on a power meter
- Quick check of power in PMC input / refl / trans to see if loss is insane
- Block each arm and add a lens after the oven to make the spot (~500 um diam?) large at stolen ISS PDs
- Check that the size is still fine @ the green PDs
- Put Green PDs into my electronics box (that's where their transimpedance amps are)
- Align and check contrast defect. Pic of PDs on scope with PZT sweeping - verify
- Get more Green PD batteries just in case (maybe before 1 if I have to order)
- 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
- Move the ovens around along the axis to try to get a maximum power
- 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.
- Balance PDs (May have to replace op amps if any are bad at this point)
- Sweep the PZT of the MZ
- 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
- Look at the Lissajous, make its crossing zero (so we can have Green Diff and IR Diff both be ~ zero)
- Get Min / Max of Lissajous for calibration
- Attempt to lock the Mach Zehnder (by first turning down the MZ gain, then increasing once lock is acquired)
- Post calibrated phase noise spectum to the elog
- 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
- Calibrate the PZT Drive signal?
- Make a breakout cable from the front of the HV PZT Drive Box (On the PZT VMON output - D9 to BNC)
- Sweep PZT, look at ERR (phase noise difference, already calibrated)
- Have calibrated control signal now!
- Add thermometer to ADC
- Use the silver epoxy to directly glue temperature sensors from Frank to the oven
- Power them with an AD587 in series with some resistor (not really a current source, but it's fine)
- Calibrate thermometer using temperature sensor already on oven (RTDs), readout by the Newport 3040 temperature controller
- Add to ADC as calibrated readout of each oven temperature
- Subtract!?!?
- Look at coherence between temperature and phase noise in green (I expect there to be some)
- Do frequency domain subtraction of Temperature from Green Phase Noise with the scripts which I already wrote (this is easy)
- Compare the suppressed level of Green phase noise with the servod IR phase noise
- Compare suppression level to known noise floor of experiment. Figure out how best to present this plot
- ????????
- Profit.
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