40m QIL Cryo_Lab CTN SUS_Lab CAML OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 316 of 357  Not logged in ELOG logo
ID Date Authorup Type Category Subject
  14597   Wed May 8 19:04:20 2019 ranaUpdatePSLPSL turned on again
  1. Increased PSL HEPA Variac from 30 to 100% to get more airflow.
  2. All of the TEC setpoints seem cold to me, so I increased the laser crystal temperature to 30.6 C
  3. Adjusted the diode TEC setpoints individually to optimize the PMC REFL power (unlocked). DTEC A = 22.09 C, DTEC B = 21.04 C
  4. locked PMC at 1900 PT; let's see how long it lasts.

My hunch is that the TECs are working too hard and can't offload the heat onto the heat sinks. As the diode's degrade, more of the electrical power is converted to heat in the diodes rather than 808 nm photons. So hopefully the increased airflow will help.

I tried to increase the DTEC setpoints, but that seems to detune them too far from the laser absorption band, so that's not very efficient for us. IN any case, if we end up changin the laser temperature, we'll have to adjust the ALS lasers to match, and that will be annoying.


The office area was very cold and the HVAC air flow stronger than usual. I changed the setpoint on the thermostat near Steve's desk from 71 to 73F at 1830 today.

  14598   Wed May 8 22:11:46 2019 ranaSummaryComputersnew laptop setup: ASIA - yum issues
  • setup controls user using K Thorne LLO CDS offsite workstation instructions
  • modified /etc/fstab ala pianosa to NFS mount disks
  • set up symlinks as other workstations
  • troubles with libsasl2 and libmetaio libraries as usual for SL7 - doing symlink tricks
  • setup shared .bashrc
  • now running 'yum install gds-all' to see if we need more local libraries to run GDS from the shared disks...
  14646   Mon Jun 3 16:40:48 2019 ranaUpdateCamerasTelescope

no BMP files crying

  14668   Thu Jun 13 14:28:46 2019 ranaUpdateCamerasGigE setup

don't need to lock - make sure the 4 OSEMs are centered on the camera field just as we have for the arm cavity mirrors


I'm attaching a picture of the screen. I just positioned the enclosure by turning it a bit and I suppose we can see the mirror inside the vacuum now (the MC2 is still not locked). 


  14701   Wed Jun 26 18:28:24 2019 ranaUpdateIOOPMC and IMC locked again, some MEDM maintenance

a useful piece of code that we should ask one of this summer's SURFs to write:

  1. read in a BURT .req file which is usually used to make the autosnap / restore.
  2. change ALL of the values to some value (slightly different from its current value)
  3. restore it to its current value

this will solve the sticky slider problem and do it in a systematic way. We can run it from the command line: e.g. 'unsticky.py c1psl c1ioo c1lsc'


Aaron complained to me earlier that the PMC could not be locked. Turned out to be a classic sticky slider problem,

  14709   Sun Jun 30 19:47:09 2019 ranaUpdateIOOIMC WFS agenda

we are thinking of doing a sprucing up of the input mode cleaner WFS (sensors + electronics + feedback loops)

  1. WFS Heads
    1. it has been known since ~2002 that the RF circuits in the heads oscillate. 
    2. in the attached PDF you can see that 2 opamps (U3 & U4; MAX4106) are used to amplify the tank circuit made up of the photodiode capacitance and L6.
    3. due to poor PCB layout (the output of U4 runs close to the input of U3) the opamps oscillate if the if the Reed relay (RY2) is left open (not attenuating)
    4. we need to remove/disable the relay
    5. also remove U3 for each quadrant so that it has a fixed gain of (TBD) and a 50 Ohm output
    6. also check that all the resonances are tuned to 1f, 2f, & 3f respectively
  2. Demod boards
  3. DC quadrant readouts
  4. Whitening
  5. Noise budget of sensors, including electronics chain
  6. diagonalization of sensors / actuators
  7. Requirements -
  8. Optical Layout
  9. What does the future hold ?

  1. what is our preferred pin-for-pin replacement for the MAX4106/MAX4107? internet suggests AD9632. Anyone have any experience with it? The Rabbott uses LMH6642 in the aLIGO WFSs. It has a lower slew rate than 9632, but they both have the same distortion of ~ -60 dB for 29.5 MHz.
  2. the whole DC current readout is weird. Should have a load resistor and go into the + input of the opamp, so as to decouple it from the RF stuff. Also why such a fast part? Should have used a OP27 equivalent or LT1124.
  3. LEMO connectors for RF are bad. Wonder if we could remove them and put SMA panel mount on there.
  4. as usual, makes me feel like replacing with better heads...and downstream electronics...
Attachment 1: WFS-Head.pdf
  14735   Mon Jul 8 21:42:39 2019 ranaUpdateCamerasGhost image due to beamsplitter

you have to use a BS with a larger wedge angle (5 arcmin ~ 1 mrad) so that the beams don't overlap on the camera

  14793   Sun Jul 21 20:23:35 2019 ranaUpdateIOOMC locked

I found the MC2 face camera disabled(?) and the MC servo board input turned off. I turned the MC locking back on but I don't see any camera image yet.

  14794   Sun Jul 21 22:16:34 2019 ranaUpdateGeneralrossa Xdisp bricked

"bricked" is to mean that it has the functionality of a brick and can be tossed. But rossa seems to have just gotten some software config corruption. I spent a couple hours reinstalling SL7 today as per my previous elog notes and the X display seems to work as before.

i.e. it was fine with the default setup, except for the ole "X chrashes if the mouse goes to left side of screen". As before, I

  1. blacklisted the nouvaeu driver (which is used by default)
  2. download the NVIDIA driver as per the link
  3. run its installation from the no-X terminal

left side of screen is safe again

This time I installed SL7.6 and followed the K Thorne wiki. But its having trouble installing cds-root because it can't find root.frown


  14799   Mon Jul 22 21:04:40 2019 ranaUpdateComputersmaking rossa great again
  • copied over /etc/fstab lines from pianosa sothat the NFS mounts work correctly
  • added symlinks so that the NFS dirs mount in the right dirs
  • installed Opera browser
  • symlink libsasl2.so.3 -> libsasl2.so.2 and now DTT runs and can get data now and in the past
  • DTT can natively produce PDF so you don't have to take screen caps of your camera phone and make a chalk drawing of that anymore
  • sitemap/MEDM is working
  • after editing fonts.alias as detailed in Thorne wiki, I ran 'sudo xset fp rehash' to get MEDM to notice new fonts. MEDM Scalable fonts are back!!
  • installed Grace and now dataviewer works
  • ndscope not running: yum install ndscope breaks because it can't find a couple of python34 packagesno
  • tested that AWGGUI also runs and puts in real sine waves
Attachment 1: seis.pdf
  14818   Tue Jul 30 20:11:12 2019 ranaSummaryIMCIMC ASC: thoughts and hopes

One of the biggest challenges in LIGO is reducing the alignment control noise. If you haven't worked on it for at least a few years, it probably seems like a trivial problem. But all versions of LIGO since 2001 have been limited by ASC noise below ~50 Hz.

I think the 40m IMC is a good testbed for us to try a few approaches towards mitigating this noise in LIGO. The following is a list of steps to take to get there:

  1. Using step responses and TF measurements, characterize the full existing system: SISO loop shapes, cross-couplings, and how diagnonal is the input and output matrices of the WFS. In principle, since we have 2 WFS in reflection and 1 DC QPD in the MC2 transmission, we should have full sensing of all angular DoFs.
  2. Check the correct operation of the WFS heads and the whole RF chain. We want the gains in the system to be such that either the shot noise or the RF electronics noise of the head is the limiting broadband noise in the system.
  3. Balancing the gains and phases of the demodulated signals is tricky, because we have no good reference. Should we use the JenneAM laser or the PSL beam?
  4. Estimate the coupling from the angular feedback signal to the IMC length noise using (1) sine wave injections for linear coupling, and (2) broadband noise for nonlinear coupling.
  5. We think the bilinear noise is due to the beam spot motion modulating the angle to length coupling as sensed by the laser beam. If this is true, we can increase the low frequency gain to minimize the beam spot motion (is this true?).
  6. By sinusoidally driving the mirror angles we can measure the instantaneous beam spot positions. We can then derive the matrix required to convert from our angular sensors (WFS + QPD) into beam spot motion. We should modify our IMC-WFS real-time model to give us DAQ channels which are beam spot estimators.
  7. Build a simulation of an IMC which has WFS, QPD, shot noise, and seismic noise.
  8. Use our optimal linear-feedback design tools to make Angular loops which minimize the bilinear noise coupling.
  9. Build a nonlinear controller (neural networks: dense + CNN) that outperforms the linear one by estimating the beam spot motion continuously and driving the cavity length to cancel the angle-to-length noise. 

I think that steps 1-6 are well within our existing experience, but we should do it anyway so as to reduce the IMC beam motion at low frequencies, and also to reduce the 10-100 Hz frequency noise as seen by the rest of the interferometer.

Steps 7-8 are medium hard, but we can get some help from the CSWG in tackling it.

Step is pretty tough, but I would like to try it and also get some help from MLWG and CSWG to address it.

  14847   Fri Aug 16 04:24:03 2019 ranaUpdateALSALS sensing noise due to IMC

What about just use high gain feedback to MC2 below 20 Hz for the IMC lock? That would reduce the excess if this theory is correct.

  14859   Thu Sep 5 20:30:43 2019 ranaHowToCDSWFS discussion, restarting CDS

via Polish chat, GV tells us to RTFE

  14864   Fri Sep 6 18:08:29 2019 ranaUpdateComputersAlarm noise from smart-ups machine under workstation?

please no one touch the UPS: last time it destroyed ROSSA. Please ask Chub to order the replacement batteries so we can do this in a controlled way (fully shutting down ALL workstations first). Last time we wasted 8 hours on ROSSA rebuilding.


There was an alarm sound from the Smart-UPS 2200 sitting under the workstation. I see that the 'replace battery' light is red, and this elog tells me that these batteries are replaced every ~1-4 years; the last replacement was march 2016. Holding down the 'test' button for 2-3 seconds results in the alarm sound and does not clear the replace battery indicator.

  14878   Mon Sep 16 05:08:04 2019 ranaUpdateIOOWFS loop measurements

not need to use DTT. I'm attaching some half-finished notebooks that give the gist.

  1. Download the data with NDS2
  2. Downsample the data for ease of use.
  3. save the data as hdf5 for easy loading later.
  4. demodulate the data at the specified frequencies.

That's it! Now you have the complex, single frequency TFs. Next you invert the matrix.

Attachment 1: LSCsensingMatrix.ipynb
 "cells": [
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Get some ASC data - Calculate Sensing Matrix \n",
    "### also make the radar plots"
... 327 more lines ...
Attachment 2: ASCsensingMatrix.ipynb
 "cells": [
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Get some ASC data - Calculate Sensing Matrix \n",
    "### also make the radar plots"
... 325 more lines ...
  14905   Mon Sep 23 10:49:34 2019 ranaUpdateCDSc1iscaux testing
  • I'd say permanently enable AA and AI. There's no reason to turn these off for usual channels. We can always undo one switch later if we want to use aliasing to sample a high frequency signal (ala SoCal).
  • The PD output should ~20 nV/rHz into the mixer, so that's ~7 nV into the whitening filter. We need 60 dB to be above the ADC noise.
  • I've forgotten what the current config is, but in iLIGO we hacked in a fixed whtiening on the Lt1128 input amp to the WF board so that the lock acquisition could be a little easier (better SNR). On Ch1, that's replacing R60 with a RC network. We want to make sure that the lock acq transients are not saturating the ADC, but can maybe put in a 40:200 stage.
  14925   Wed Oct 2 20:45:18 2019 ranaUpdateComputersrossa revival

Formatted and re-installing OS on rossa for the 3rd or 4th time this year. I suggest that whoever is installing software and adjusting video settings please stop.

If you feel you need to tinker deeply, use ottavia or zita and then be prepared to show up and fix it.

While I was moving the UPS around, the network lights went out for Rossa, so I may have damaged the network interface or cable. Debugging continues.

  14928   Thu Oct 3 11:01:18 2019 ranaUpdateLSC(PR)FPMI locking

wonder if its possible to do variable finesse locking

Gabriele mentioned that Virgo used arm trans PDH for this, but I guess we could possibly use POX/POY to start and bring in the PRM with 50% MICH trans

  14931   Thu Oct 3 14:32:37 2019 ranaUpdateGeneralMake the Jenne-laser setup fiber-coupled

I'm curious to see if we really need the 1611, or if we can calibrate the diode laser vs. the 1611 one time and then just use that calibration to get the absolute cal for the DUT.

  14935   Thu Oct 3 21:50:22 2019 ranaUpdateComputersrossa revival

Got the network to work again just by unplugging the power cord and letting it sit for awhile. But corrupted OS by trying to install Nvidia drivers.


  14952   Tue Oct 8 16:54:56 2019 ranaUpdateIOOIMC locking not working after this work

I think this offset setting thing is not so good. People do this every few years, but putting offsets in servos means that you cannot maintain a stable alignment when there are changes in the laser power, PMC trans, etc. The better thing is to do the centering of the WFS spots with the unlcoked beam after the control offsets have been offloaded to the suspensions.

  14959   Wed Oct 9 12:15:05 2019 ranaUpdateElectronicsWFS head RF measurements

It would be good if you and Shruti can look at how to change the parameters in Zero so as to do a fit to the measured data. Usually, in scipy.optimize we give it a function with some changeable params, so maybe there's a way to pass params to a zero object in that way. I think Ian and Anchal are doing something similar to their FSS Pockel's cell simulator.

  14986   Wed Oct 23 10:23:26 2019 ranaUpdateALSEX uPDH electronics checkout

During our EX AM/PM setups, I don't think we bumped the PDH gain knob (and I hope that the knob was locked). Possible drift in the PZT response? Good thing Shruti is on the case.

Is there a loop model of green PDH that agrees with the measurement? I'm wondering if something can be done with a compensation network to up the bandwidth or if the phase lag is more like a non-invertible kind.

  14994   Mon Oct 28 18:55:06 2019 ranaUpdateComputersrossa revival

back on new Rossa from Xi computing

  1. switched to using Display Port for video; this works. The DVi, HDMI, VGA ports are connected to the motherboard rather than the video card, so they are not active.
  2. runs super slow w/ SL 7.6; maybe some service is running after startup?
  3. install repos and update according to LLO CDS wiki
  4. add controls user and group according to LLO wiki
  5. remove gstreamer ugly because it breaks yum update
  6. run 'yum update --skip-broken' because GDS doesn't work
  7. turn off old selinux stuff
  8. modify fstab to get NFS


  1. finish mounting
  2. xfce
  3. figure out why the LLO install instructions can't install any CDS software (e.g. root, DTT, etc)

Update: Sun Nov 3 18:08:48 2019

  1. moved the SL7 fresh install repos back into etc/yum.repos.d/. The LLO instructions has me remove them, but the LLO supplied repos are no good for standard apps. After putting these back was able to install standard apps (terminator, root, diaggui)
  2. copied over /etc/fstab lines from pianosa sothat the NFS mounts work correctly
  3. added symlinks so that the NFS dirs mount in the right dirs
  4. symlink libsasl2.so.3 -> libsasl2.so.2 and now DTT runs and can get data now and in the past
  5. install XFCE
  6. sitemap / MEDM works
  7.  Did "sudo ln -s /usr/lib64/libXm.so.4 /usr/lib64/libXm.so.3" to enable StripTool.

Update: Fri Nov 15 00:00:26 2019:

  1. random hanging of machine while doing various window moving or workspace switching
  2. turned off power management in XFCE
  3. turned off power management on monitor
  4. disabled SELINUX
  5. firewalld was already off
  6. installed most, pdftk, htop, glances, qtgrace, lesstif
  7. dataviewer now works and QTgrace is much nicer than XMGrace
  15023   Wed Nov 13 20:15:56 2019 ranaUpdatePEMFollow-up on seismometer discussion

this is due to the Equivalence Principle: local accelerations are indistinguishable from spacetime curvature. On a spherical Earth, the local gradient of the metric points in the direction towards the center of the Earth, which is colloquially known as "down".


I don't understand why the z-axis motion reported by the T240 is ~10x lower at 10 mHz compared to the X and Y motions. Is this some electronics noise artefact?


  15025   Thu Nov 14 12:11:04 2019 ranaUpdatePEMFollow-up on seismometer discussion

at 1 Hz' this effect is not large so that's real translation. at lower frequencies a ground tilt couples to the horizontal sensors at first order and so the apparent signal is amplified by the double integral. drawing a free body diagram u can c that

x_apparent = (g / s^2) * theta

but for vortical this not tru because it already measures the full free fall and the tilt only shows up at 2nd order

  15026   Thu Nov 14 23:56:18 2019 ranaUpdateLSCoff the bad Violin filters

We turned off many excessive violin mode bandstop filters in the LSC.

Due to some feedforward work by Jenne or EQ some years ago, we have had ~10 violin notches on in the LSC between the output matrix and the outputs to the SUS.

They were eating phase, computation time, and making ~3 dB gain peaking in places where we can't afford it. I have turned them off and Gautam SDF safed it.

Offensive BS shown in brown and cooler BS shown in blue.

To rotate the DTT landscape plot to not be sideways, use this command (note that the string is 1east, not least):
pdftk in.pdf cat 1east output out.pdf

Attachment 1: out.pdf
  15027   Fri Nov 15 00:18:41 2019 ranaUpdatePEMFollow-up on seismometer discussion

The large ground motion at 1 Hz started up again tonight at around 23:30. I walked around the lab and nearby buildings with a flashlight and couldn't find anything whumping. The noise is very sinusoidal and seems like it must be a 1 Hz motor rather than any natural disturbance or traffic, etc. Suspect that it is a pump in the nearby CES building which is waking up and running to fill up some liquid level. Will check out in the morning.

Estimate of displacement noise based on the observed MC_F channel showing a 25 MHz peak-peak excursion for the laser:

dL = 25e6 * (13 m / (c / lambda)

      = 1 micron

So this is a lot. Probably our pendulum is amplifying the ground motion by 10x, so I suspect a ground noise of ~0.1 micron peak-peak.

(this is a native PDF export using qtgrace rather than XMgrace. uninstall xmgrace and symlink to qtgrace.)

Attachment 1: MCshake.pdf
  15031   Fri Nov 15 18:59:08 2019 ranaUpdateComputersZITA: started upgrade from Ubuntu 14 LTS to 18 LTS

and so it begins...until this is finished I have turned off the projector and moved the striptools to the big TV (time to look for Black Friday deals to replace the projector with a 120 inch LED TV)

  15050   Tue Nov 26 18:16:08 2019 ranaUpdateLSCPOX / POY calibration

...maybe the opto-mechanical CARM plant is changing as a function of the CARM offset...


Even assuming 50% error in the calibration factors, it's hard to explain the swing of TRX/TRY when the CARM offset is brought to zero.

  • The increase in (admittedly in-loop) CARM noise as the offset is reduced still seems to me to be correlated with the buildup of IR power in the arm cavities.
  15052   Wed Nov 27 13:14:02 2019 ranaUpdateLSCITMX and ITMY OSEMs with low and high circulating power

if the RP don't fit

u must acquit

sweep the laser amplitude

to divine the couplin w certitude

  15057   Sun Dec 1 13:38:48 2019 ranaUpdateLSCNo shaking but no inspiration either

yes, reasonable

  15060   Mon Dec 2 20:18:18 2019 ranaUpdateALSEY uPDH post mixer LPF

                   filter Q seems too high,

but what precisely is the proper way to design the IF filter?

   seems like we should be able to do it using math instead of feelins

                              Izumi made this one so maybe he has an algorythym

  15065   Tue Dec 3 14:52:13 2019 ranaUpdateIMCQ Measurement of Test Masses



[Yehonathan, Gavin]

  1. Lock IMC
  2. Lock one of the arms (only) using the IR PDH signal feeding back to an ETM.
  3. Excite the ITM using the SR785 near 28.8 kHz
  4. Look for the resulting peak using the SR785 spectra of the POX or POY error signal from the demod board
  5. Based on the calibrated noise level of the POX/POY, estimate what the SNR will be of the internal mode peak.
  15067   Tue Dec 3 20:32:37 2019 ranaOmnistructureDAQNDS2 situation

Recently, accordian to Gautam, the NDS2 server has been dying on Megatron ~daily or weekly. The prescription is to restart the server.

  1. I could find no instructions (that work) in the elog or wiki. We must remove the misleading entries from the wiki and update it with whatever works as of today.
  2. There is a line (which has been commented out) in the Megatron crontab which is close to the right command, but it has the wrong path.
  3. Running the command from the CRON (/home/nds2mgr/nds2-megatron/test_restart), gives several errrors.
  4. when I run the init.d command which is in the script, it seems to run fine
  5. the server then takes several minutes to get itself together; i.e. just because it is running doesn't mean that you can get data. I recommend waiting 5-10 minutes.

Also, megatron is running Ubuntu 12 !! Let's decide on a day to upgrade it to a Debian 18ish....word from Rolf is that Scientific Linux is fading out everywhere, so Debian is the new operating system for all conformists.

Attachment 1: getData.py
#!/usr/bin/env python
# this function gets some data (from the 40m) and saves it as
# a .mat file for the matlabs
# Ex. python -O getData.py

from scipy.io import savemat,loadmat
import scipy.signal as sig
from astropy.time import Time
import nds2
... 116 more lines ...
Attachment 2: chanlist.txt
  15082   Fri Dec 6 17:49:46 2019 ranaSummaryPEMJump test of seismometers: EX needs recentering

Yehonathan, please center the EX seismometer.

The attached PDF shows the seismometer signals (I'm assuming that they're already calibrated into microns/s) during the lab tour for the art students on 11/1. The big spike which I've zoomed in on shows the time when we were in the control room and we all jumped up at the same time. There were approximately 15 students each with a mass of ~50-70 kg. I estimate that out landing times were all sync'd to within ~0.1 s.

Attachment 1: Seismometers.pdf
Attachment 2: src.tgz
  15083   Sun Dec 8 20:15:41 2019 ranaSummaryPEMJump test of seismometers: EX needs recentering

I have re-centered the EX (and EY) seismometers. They are Guralp CMG40-T, and have no special centering procedure except cycling the power a few times. I turned off the power on their interface box, then waited 10s before turning it back on.

The fist atm shows the comparison using data from 8-9 PM Saturday night:

  1. there seems to be a factor of 2 calibration diff between the T240 near the BS, and the Guralp seismometers at the end. Which one is right? surpriseWhen was the last time they were cross calibrated?
  2. The low coherence between BS_X and EX_X shows the problem. They should be very coherent (> 0.9) for 0.1-1 Hz.sad


Attachment 1: seis_all_191208.pdf
  15084   Sun Dec 8 20:27:11 2019 ranaUpdateComputersViviana upgrade to Ubuntu 16

The IBM laptop at EX was running Ubuntu 14, so I allowed it to start upgrading itself to Ubuntu16 as it desired. After it is done, I will upgrade it to 18.04 LTS. We should have them all run LTS.

  15085   Sun Dec 8 20:48:29 2019 ranaConfigurationComputersMegatron: starts up grade

I noticed recently that Megatron was running Ubuntu 12, so I've started its OS upgrade.

  1. Unlocked the IMC + disabled the autolocker from the LockMC screen + closed the PSL shutter (IMC REFL shutter doesn't seem to do anythin)
  2. Disabled the "FSS" slow servo on the FSS screen
  3. did sudo apt-get update, sudo apt-get upgrade, and then sudo apt-get do-release-upgrade which starts the actual thing
  4. According to the internet, the LTS upgrades will go in series rather than up to 18 in one shot, so its now doing 12 -> 14 (Trusty Tapir)

Megatron and IMC autolocking will be down for awhile, so we should use a different 'script' computer this week.

Mon Dec 9 14:52:58 2019

upgrade to Ubuntu 14 complete; now upgrading to 16

  15095   Wed Dec 11 22:01:24 2019 ranaConfigurationComputersMegatron: starts up grade

Megatron is now running Ubuntu 18.04 LTS.

We should probably be able to load all the LSC software on there by adding the appropriate Debian repos.

I have re-enabled the cron jobs in the crontab.

The MC Autolocker and the PSL NPRO Slow/Temperature control are run using 'initctl', so I'll leave that up to Shruti to run/test.

  15102   Tue Dec 17 20:45:30 2019 ranaUpdatePSLPMC cavity ringdown measurement

idk - I'm recently worried about the 'thermal self locking' issue we discussed. I think you should try to measure the linewidth by scanning (with low input power) and also measure the TF directly by modulating the power via the AOM and taking the ratio of input/output with the PDA55s. I'm curious to see if the ringdown is different for low and high powers


I plan to model the PD+AOM as a lowpass filter with an RC time constant of 12us and undo its filtering action on the PMC trans ringdown measurement to get the actual ringdown time.

Is this acceptable?

This is an ole SURF report on thermal self-locking that may be of use (I haven't read it or checked it for errors, but Royal was pretty good analytically, so its worth looking at)

  15141   Wed Jan 22 16:38:01 2020 ranaUpdateComputersrossa revival

wiped and install Debian 10 on rossa today

still to be done: config it as CDS workstation

please don't try to "fix" it in the meantime

  15146   Thu Jan 23 16:37:14 2020 ranaUpdatePSLPMC VGA chip damaged?

doesn't seem so anomolous to me; we're getting ~25 dB of gain range and the ideal range would be 40 dB. My guess is that even thought this is not perfect, the real problem is elsewhere.

  15162   Tue Jan 28 08:26:53 2020 ranaFrogsPEMshaking


  15193   Thu Feb 6 16:14:44 2020 ranaUpdateGeneraloffice area temperature

I changed the office area thermostate near Steve's desk from 68F to 73F today. Please do not change it.

If anyone from facilities comes to adjust something, please put the details in the elog on the same day so that we can know to undo that change rather than chase down other drifts in the system.

  15217   Wed Feb 19 22:20:22 2020 ranaUpdateALSALS OOL noise with arms locked

Could you please put physical units on the Y-axis and also put labels in the legend which give a physical description of what each trace is?

It would also be good to a separate plot which has the IR locking signal and the green locking signal along with this out of loop noise, all in the same units so that w can see what the ratio is.

  15221   Sun Feb 23 18:15:22 2020 ranaUpdateALSALS OOL noise and PDH

to make the comparisons meaningfully

one needs to correct for the feedback changes


  15269   Thu Mar 12 10:43:50 2020 ranaUpdateLoss MeasurementArm transfer function measurement

                               when doing the AM sweeps of cavities

make sure to cross-calibrate the detectors

                       else you'll make of science much frivolities

            much like the U.S. elections electors

  15286   Mon Mar 30 19:02:49 2020 ranaUpdateGeneraldonated cleanroom supplies to Hospitals

Yesterday evening I took nearly all of the masks, gloves, gowns, alcohol wipes, hats, and shoe covers. These were the ones in the cleanroom cabinets at the east end of the Y-arm, as well as the many boxes under the yarm near those cabinets.

This photo album shows the stuff, plus some other random photos I took around the same time (6-7 PM) of the state of parts of the lab.

  15288   Tue Mar 31 23:35:50 2020 ranaUpdateCDSFoton for shaped noise injections

do you really mean awggui cannot make shaped noise injections via its foton text box ? That has always worked for me in the past.

If this is broken I'm suspicious there's been some package installs to the shared dirs by someone.

ELOG V3.1.3-