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ID Date Author Type Categorydown Subject Text Attachments
  13688   Mon Mar 19 15:02:29 2018 gautamUpdateALSNoisy MC sensingThe working hypothesis, since the excess
noise in single arm locks is coherent between
both arms, the excess sensing noise is frequency
  
  13749   Thu Apr 12 18:12:49 2018 gautamUpdateALSNPRO channels hijackedSummary:


Today,
the measured IR ALS noise for the X arm was
dramatically improved. The main change was
 IR_ALS_20180412.pdfBeatMouthDrift.pngETMX_20180416.jpg 
  13751   Fri Apr 13 11:02:41 2018 gautamUpdateALSEX fiber polarization driftAttachment #1  EX_pol_drift.png 
  13752   Fri Apr 13 16:59:12 2018 gautamUpdateALSEX green mode-matchingTHIS CALCULATION   
  13753   Fri Apr 13 17:56:26 2018 gautamUpdateALSFibers switched outI swapped the EX fiber for the PSL fiber
in the polarization monitoring setup. There
is a lot more power in this fiber, and one
  
  13754   Sat Apr 14 14:42:09 2018 gautamUpdateALSFibers switched outIt looks like the drift in polarization
content in the PSL pickoff is actually much
higher than that in the EX pickoff. Note
 PSLdrift.png 
  13757   Tue Apr 17 14:08:29 2018 gautamUpdateALSFibers switched outA follow-up on the discussion from today's
lunch meeting - Rana pointed out that rotation
of the fiber in the mount by ~5degrees cannot
 PSL_fluctuations.png 
  13773   Fri Apr 20 00:26:34 2018 gautamUpdateALSFibers switched outSummary:

  
  13779   Sat Apr 21 20:25:12 2018 gautamUpdateALSPSL fiber pickoff statusSeems like there is still a bit of variation
in the power in the two polarizations, though
it is much smaller now, at the ~5% level
 PSL-beatMouthPickoff.png 
  13784   Tue Apr 24 11:31:59 2018 gautamConfigurationALSProposed changes to EX fiber couplingMotivation:
I want to make another measurement of the
 EX_fiber_MM.pdfEX_fiber_changes.png 
  13786   Tue Apr 24 18:54:15 2018 gautamConfigurationALSProposed changes to EX fiber couplingI started working on the EX table. Work
is ongoing so I will finish this up later
in the evening, but in case anyone is wondering
  
  13789   Wed Apr 25 19:09:37 2018 gautamConfigurationALSNew look EX Fiber couplingSummary:

I implemented most of the things
outlined in my previous elog.
 EX_fiber_MM.pdfIMG_6977.JPGIMG_6972.JPGIMG_6974.JPGIMG_6976.JPG 
  13791   Thu Apr 26 11:24:50 2018 gautamConfigurationALSNew look EX Fiber coupling - pol stabilityHere is a first look at the overnight stability.
For the temperature, I used the calibration
I found in the old psl database file, seems
 polStab.pdf 
  13792   Thu Apr 26 18:58:21 2018 BruceConfigurationALSNew look EX Fiber coupling - pol stability    
  13796   Fri Apr 27 01:36:02 2018 gautamConfigurationALSIR ALS noise performanceSummary:

My goal was to do some further
characterization of the IR ALS system tonight.
 2018_04_BeatMouth_POX.pdf2018_04_BeatMouth.pdfALSSpecgram.pdfALS_ASD.pdfALSstab.pdf 
  13807   Wed May 2 21:39:33 2018 gautamConfigurationALSIR ALS for EYThe new K6XS mounts I ordered have arrived.
I want to install one of them at the Y-end.
I can't find a picture of the current
  
  13817   Fri May 4 21:17:57 2018 gautamConfigurationALSBeathMouth pulled out of PSL tableI have been puzzled about the beat note
level we get out of the BeatMouth for some
time.
  
  13824   Tue May 8 00:40:51 2018 gautamConfigurationALSBeathMouth pulled out of PSL tableSummary:

I did some more BeatMouth characterization.
My primary objective was to do a power budget.
 IMG_6986.JPGIMG_6987.JPG 
  13886   Thu May 24 13:06:17 2018 gautamConfigurationALSDFD noisesSummary:


The DFD noise floor is
~0.5Hz/rtHz
 DFDcalib.pdfDFD_NB.pdf 
  13889   Thu May 24 19:41:28 2018 gautamConfigurationALSBeathMouth reinstalled on PSL tableSummary:


DC light power incident
on beat PD is 
  
  13890   Thu May 24 20:31:03 2018 gautamConfigurationALSDFD noisesA
couple of months ago, I took 21 measurements
of the delay line transfer function. As shown
 TF_X_mag.pdfTF_X_phase.pdf 
  13955   Wed Jun 13 12:21:09 2018 gautamUpdateALSPDFR laser checkoutI want to use the Fiber Coupled laser from
the PDFR
system to characterize the response of
  
  13957   Wed Jun 13 22:07:31 2018 gautamUpdateALSBeatMouth PDFR measurementSummary:

Neither
 IMG_7056.JPGBeatMouthPDFR.pdfBeatMouth_PDFRdata.tgz 
  13973   Fri Jun 15 14:22:05 2018 gautamUpdateALSBeatMouth PDFR measurementI did the measurement with the BeatMouth
open today. Main changes:


Directly pipe the RF output
 BeatMouthPDFR.pdfBeatMouth_PDFRdata.tgz 
  14468   Wed Feb 20 23:55:51 2019 gautamUpdateALSALS delay line electronicsSummary:

Last year, I worked
on the ALS delay line electronics, thinking
 delayLineDemod.pdf.zip 
  14475   Thu Mar 7 01:06:38 2019 gautamUpdateALSALS delay line electronicsSummary:

The restoration of the delay-line
electronics is complete. The chassis has
  
  14477   Tue Mar 12 22:51:25 2019 gautamUpdateALSALS delay line electronicsThis
Hanford alog may be of relevance as we
are using the aLIGO AA chassis for the IR
  
  14478   Wed Mar 13 01:27:30 2019 gautamUpdateALSALS delay line electronicsThis test was done, and I determine the
frequency discriminant to be 
 DFDcal.pdfDFDnoise.pdf 
  14479   Thu Mar 14 23:26:47 2019 AnjaliUpdateALSALS delay line electronicsAttachment #1 shows the schematic of the
test setup. Signal generator (Marconi) was
used to supply the RF input. We observed
 test_setup_ALS_delay_line_electronics.pdf 
  14480   Sun Mar 17 00:42:20 2019 gautamUpdateALSNF1611 cannot be shot-noise limited?Summary:

Per the manual (pg12)
of the NF 1611 photodiode, the "Input
 PDnoise.pdf 
  14481   Sun Mar 17 13:35:39 2019 AnjaliUpdateALSPower splitter characterizationWe characterized the power splitter ( Minicircuit-
ZAPD-2-252-S+). The schematic of the measurement
setup is shown in attachment #1. The network/spectrum/impedance
 Measurement_setup.pdfTotal_loss.pdfAmplitude_unbalance.pdfPhase_unbalance.pdf 
  14482   Sun Mar 17 21:06:17 2019 AnjaliUpdateALSAmplifier characterisationThe goal was to characterise the new amplifier
(AP1053). For a practice, I did the characterisation
of the old amplifier.This test is similar
 Gain_measurement.pdfAmplifier_gain.pdfnoise_measurement.pdfnoise_characterisation.pdf 
  14486   Mon Mar 18 20:22:28 2019 gautamUpdateALSALS stability testI'm running a test to see how stable
the EX green lock is. For this purpose, I've
left the slow temperature tuning servo on
  
  14498   Thu Mar 28 19:40:02 2019 gautamUpdateALSBeatMouth with NF1611s assembledSummary:

The parts I was waiting for arrived.
I finished the beat mouth assembly, and did
 IMG_7381.JPGIMG_7382.JPGrelTF_schem.pdfdarkNoise.pdf 
  14502   Fri Mar 29 21:00:06 2019 gautamUpdateALSBeatMouth with NF1611s installed
Newfocus 15V current limited supply
was taken from bottom NE corner of the ITMY
Oplev table to power the BeatMouth on the
 IMG_7384.JPGIMG_7385.JPG 
  14503   Sun Mar 31 15:05:53 2019 gautamUpdateALSFiber beam-splitters not PMI looked into this a little more today.


Looking at the beat signal
between the PSL and EX beams from the
 IMG_7384.JPG 
  14510   Wed Apr 3 09:04:01 2019 gautamUpdateALSNote about new fiber couplersThe new fiber beam splitters we are ordering,
PFC-64-2-50-L-P-7-2-FB-0.3W,
have the slow axis working and fast axis
  
  14513   Wed Apr 3 12:32:33 2019 KojiUpdateALSNote about new fiber couplersAndrew seems to have an integrated solution
of PBS+HWP in a singe mount. Or, I wonder
if we should use HWP/QWP before the coupler.
  
  14516   Fri Apr 5 00:33:58 2019 gautamUpdateALSPromising IR ALS noiseSummary:

I set up a free-space
beat on theNW side of the PSL table between
 IMG_7388.JPGfreeSpace_IR_beat.pdf 
  14519   Fri Apr 5 11:49:30 2019 gautamUpdateALSPSL + X green beat recoverySince we haven't been using it, the
PID control was not enabled on the doubling
oven on the PSL table (it is disabled after
  
  14521   Mon Apr 8 00:04:08 2019 gautamUpdateALSIR ALS noise budgetTo start the noise budgeting, I decided
to measure the "DFD noise", which
is really the quadrature sum of the following
 DFDnoise.pdf 
  14523   Mon Apr 8 18:28:25 2019 gautamUpdateALSEX Green PDH checkoutI worked on characterizing the green PDH
setup at EX, as part of the ALS noise budgeting
process. Summary of my findings:
 IMG_7393.JPGgreenModeMatch.pdf 
  14524   Mon Apr 8 23:52:09 2019 gautamUpdateALSEX Green PDH error monitor calibratedSome time ago, I had done an actuator
calibration of ITMX. This suspension
hasn't been victim to the recent spate
 errMonCalib.pdferrMon.pngOLTF.pdfEX_frequencyNoises.pdf 
  14525   Tue Apr 9 00:16:22 2019 ranaUpdateALSEX Green PDH error monitor calibratedG=10 or
G=100?
  
  14526   Tue Apr 9 00:18:19 2019 gautamUpdateALSEX Green PDH error monitor calibratedwrong assumption - i checked the gain just
now, it is G=10, and is running in the "low-noise"
mode, so can only drive 4V. fixed elog, filter.
  
  14527   Tue Apr 9 18:44:00 2019 gautamUpdateALSEX Green PDH discriminant measurementI decided to use the more direct method,
of disconnecting feedback to the EX laser
PZT, and then looking at the cavity flashes. 
 cavityFlashes.pdfmodelPDH.pdf 
  14528   Tue Apr 9 19:07:12 2019 gautamUpdateALSIR ALS noise budgetUpdated the noise budget to include the
unsuppressed frequency noise from the EX
laser. It does not explain the noise
 ALS_noiseBudget.pdfALS_noiseBudget.pdf 
  14533   Thu Apr 11 01:10:05 2019 gautamUpdateALSLarge 2kHz peak (and harmonics) in ALS XThese weren't present last week. The
peaks are present in the EX PDH error monitor
signal, and so are presumably connected with
 EX_PDH_2kNoise.pdf 
  14548   Wed Apr 17 00:50:17 2019 gautamUpdateALSLarge 2kHz peak (and harmonics) in ALS X no moreI looked into this issue today. Initially,
my thinking was that I'd somehow caused
clipping in the beampath somewhere which
 EX_PDHnoise.pdf 
  14549   Wed Apr 17 11:01:49 2019 gautamUpdateALSLarge 2kHz peak (and harmonics) in ALS X no moreEX green stayed locked to XARM length overnight
without a problem. The spectrogram doesn't
show any alarming time varying features around
 EX_PDH_specGram.pdf 
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