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ID Dateup Author Type Category Subject
  5137   Mon Aug 8 00:58:26 2011 ranaUpdateCDSdiagonalization of MC input matrix

Besides the purpose of correctly tuning the suspensions, my hidden goal in the input matrix diagonalization has been to figure out what the 'true' sensing noise of the OSEMs is so that we can accurately predict the noise impact on the OAF.

The attached plot shows the DOFs of ITMX calibrated into microns or microrad as per Jamie's ethereal input matrix calculations.

The main result is in the ratio of POS to BUTTER. It tells us that even at nighttime (when this data was taken) we should be able to get some reduction in the arms at 1 Hz.

Whether we can get anything down to 0.1 Hz depends on how the arm control signal compares to the POS signal here. I leave it to Jenne to overlay those traces using a recent Arm lock.

Attachment 1: null.png
  5138   Mon Aug 8 12:08:05 2011 ranaUpdateSUSsus at atm


A plot showing that the daily variation in the OLs is sometimes almost as much as the full scale readout (-1 to +1).

  5139   Mon Aug 8 13:24:00 2011 steveMetaphysicsTreasure Monday morning


Just a reminder that a film crew will be here Monday morning, filming Christian Ott for some Discovery channel show.

They are slated to be here from 8am to 12:30pm or so.  They will take a couple of shots inside the lab, and the rest of the filming should be of Christian in the control room (which they will "clean up" and fit with "sexy lighting").  I will try to be here the whole time to oversee everything.

Konecrane Fred was early this morning. He diagnosed the ETMY crane horizontal drive gear box dead and left just before the film crew showed up.

New gear box should be here by the end of this week for installation.

The lab air quality is high ~20,000 counts of particles of 0.5 micron.  Keep an eye on this before you open the chamber.

Attachment 1: P1080147.JPG
  5140   Mon Aug 8 14:21:03 2011 steveUpdatePEMParticle counts controlled


[Jenne, Kiwamu]

While Kiwamu was finalizing the X green alignment, I started to prepare to remove the ETMY door, and begin checking out its OSEMs, etc, so we could start moving it to it's new place, and figure out why it's been wonky for a while.  I ran the particle counter, and we have a factor of ~5 more particles than normal.  Kiwamu and I agreed not to open ETMY.  Since we had briefly opened the IOO and Output Optics chambers to check the X green's position on the PSL table, we immediately shut those doors.  They were probably open for ~15 minutes or so.  (Yes Steve, we should have checked before opening any doors, but at least we remembered to check at all, and the doors were only open for a few minutes rather than for a few hours.)

I attach a 24hrs trend of the particle counts, for reference.  It looks like it's been a little high for a while, but today it's really dirty in the air.

 The east end particle count is 155K for 0.3 micron and 15K for 0.5 micron  counts/cf min.  In order to minimize diffusion of dirt into the IFO we set up the mobile HEPA with CP Stat 100 tent.

This set up gives us practically ZERO inside the tent

Attachment 1: P1080149.JPG
Attachment 2: P1080150.JPG
  5141   Mon Aug 8 15:20:49 2011 kiwamuUpdateSUSinspection on ETMY (round 1)

Since ETMY have been showing some strange behaviors we deeply inspect the ETMY suspension.

Here is a brief review of the ETMY suspension and a brief status update of the inspection so far.

The inspection is still ongoing.


(Review : How wrong ?)

First of all, let us summarize what were the observed phenomena on the ETMY suspension :

   1. unknown low frequency noise covering frequency range from 0.1 to 3 Hz in all of four face sensors (#5025, #5029).

   2. LR sensor showed a very broad bounce peak at ~ 17 Hz (#5025).

   3. The sign of some of the sensors are flipped.

   4. The control gains had to be higher than those of ETMX by 10-100 (#5025).


(Status update : Noise spectra)

Currently the ETMY suspension is sitting on the north side of the table for the inspection.

We took dark noise of the OSEMs when the OSEMs were taken off from the tower and put on the table.

The plot below is an example of the LR sensor spectra. Note that the whitening filters have been always ON.


The black curve is the dark noise when the sensor was off from the tower.

The blue curve is the free swinging spectrum newly taken today.

The red curve is the free swinging spectrum (damped spectrum ?) on 25th of July, this was still in vacuum.


The dark noise is below the free swinging spectrum from 0.2 - 30 Hz, which looks reasonable

The most interesting thing is that the free swinging spectrum became better in low frequency (below 3 Hz)

from the one measured in vacuum.

It needs more investigation to answer the reason why it happened.

Note that before we moved the tower to the current position, we looked at the OSEM-magnets relations, and found nothing was touching.


  5142   Mon Aug 8 15:52:39 2011 steveUpdateVACback ground rga scan

The RGA region is beeing monitored during the vent. This will tell us how clean the RGA itself is.


Attachment 1: bg-d5.jpg
Attachment 2: presBg-d5.jpg
  5143   Mon Aug 8 19:45:27 2011 jamieUpdateCDSactivateDQ script run; SUS channels being acquired again

> Also the BS is missing its DAQ channels again (JAMIE !) so we can't diagnose it with the free swinging method.

I'm not sure why the BS channels were not being acquired.  I reran the activateDQ script, which seemed to fix everything.  The BS DQ channels are now there.

I also noticed that for some reason there were SUS-BS-ASC{PIT,YAW}_IN1_DQ channels, even though they had their acquire flags set to 0.  This means that they were showing up like test point channels, but not being written to frames by the frame builder.  This is pretty unusual, so I'm not sure why they were there.  I removed them.

  5144   Mon Aug 8 20:23:14 2011 JennyUpdatePSLNetwork analyzer and PD set up to measure amplitude response of PZT



Today I placed the PDA255 photodiode on the PSL table to catch the small amount of beam power reflected by the second polarizing beam splitter in my setup. I plugged the PD output to the oscilloscope to measure the voltage output and positioned the PD such that the voltage output was maximized. At best I was able to achieve a 300 mV DC output voltage from the PD, (which seems a bit low, as the PD is specified to go from 0 to 5 V and the specifications say that the response becomes nonlinear after 10 mW/cm^2 and my beam has an intensity of approximately 5 mw/cm^2. I would therefore expect to get more beam power but after over an hour of maneuvering, 300 mV was the highest voltage output I could get).

I am planning, tomorrow afternoon, to take a measurement of the amplitude response of the PZT driving the NPRO laser. I moved the 4395 spectrum/network analyzer to near the PSL table and connected the RF output to an RF splitter. I fed one output of that into the PZT and the other output into the R port on the network analyzer. I fed the PD output into the A port. I plan to measure A/R as a function of driving frequency, sweeping from 10 Hz to 30 mHz.

I also worked to improve the mode matching of the NPRO beam coming from the AP table to the reference cavity. I drove the temperature of the NPRO at 0.100 Hz with an amplitude of 0.300 V, which Koji told me corresponds to a 1GHz change in the laser frequency. The transmission from the cavity is being monitored by a camera connected to a TV monitor, and also by a PD connected to an oscilloscope. I then repositioned the second lens in my mode matching setup in an attempt to increase the transmission peaks from the zeroth order spacial mode and decrease the transmission peaks from higher order modes. I may have improved the mode matching slightly but I was unable to improve it significantly.

The ABSL beam had been blocked so that it wouldn't enter the interferometer. I moved the block so that the beam I've been using is unblocked by the beam going to the interferometer is still blocked.

I positioned a fast lens (f=28.7mm) a little over an inch in front of the PDA255 in order to decrease the spot size incident on the PD. I adjusted the rotation angle of the half wave plate to maximize the transmitted power through the PBS to the cavity and minimize the power reflected to my PD. I then adjusted the lens potion to fix the beam on the PD. The voltage output of the PD is now 150mW, but I have the ability to increase the incident power by rotating the wave plate slightly.

Now all I need is to set up the network analyzer again to record the amplitude response to modulating the PZT from 10 Hz to 30 MHz, reduce the input voltage into the analyzer using a DC block.

 I rolled the network analyzer over to the PSL table (on the south side). I'm borrowing the DC block from Kiwamu's green locking setup. I'm going to first measure the amplitude response of a low pass filter to made sure that the analyzer is outputting what I expect. Then I will measure the laser PZT amplitude response. I plan to finish the measurement and return the network analyzer to it's usual location tonight.

  5145   Mon Aug 8 22:12:58 2011 NicoleSummarySUSDaily Summary

Today I balanced the mirror, finished putting together the second photosensor, and finished my photosensor circuit box! 

Upon Jamie's suggestion, I have used a translation stage to obtain calibration data points (voltage outputs relative to displacement) for the new photosensor and for the first photosensor.

I will plot these tomorrow morning (too hungry now > < )


Here is a photo of the inside of my circuit box! It is finally done! It is now enclosed in a nice aluminum casing ^ ^



Attachment 1: frontview.jpg
  5146   Tue Aug 9 01:35:45 2011 SureshUpdateSUSETMX Side Sensor slow channel down for a long time

The slow signal from the side sensor on ETMX was last seen in action sometime in May 2010!  And then the frame builder has no data for a while on this channel.  After that the channel shows some bistability starting Sept 2010 but has not been working.  The fast channel of this sensor  (C1:SUS-ETMX_SDSEN_OUTPUT) does work so the sensor is working.  Probably is a loose contact... needs to be fixed.

ETMX-SDSEN_trend1.png         ETMX_SDSEN_trend2.png


  5147   Tue Aug 9 02:03:16 2011 kiwamuSummarySUSsummary of today's work on ETMY

[Rana / Jenne / Kiwamu]

The ETMY suspension tower is currently sitting on the north side of the table for some inspections.

The adjustment of the OSEMs is ongoing.


(What we did)

  + Taken out two oplev mirrors, Jamie's windmill and a lemo patch panel.

  + Put some pieces of metal as makers for the original place

  + Put some makers on the distance of  dLY = -25.49 cm = -10.04 inch from the original place (see the 40m wiki).

     The minus sign means it will move away from the vertex.

  + Brought the ETMY suspension tower to the north side to do some inspections

  + Did some inspections by taking the noise spectra (#5141)

  + Adjusted the OSEM range and brought the magnets on the center of the OSEM holders by rotating and translating the OSEMs

  + During the work we found the proper PIT and YAW gains were about -5, which are the opposite sign from what they used to be.

  + Trying to minimize the cross couplings

JD: There is still some funny business going on, like perhaps the LR magnet isn't quite in the OSEM beam.  We leave the optic free swinging, and will continue to investigate in the morning.

  5148   Tue Aug 9 02:27:54 2011 Ishwita , ManuelUpdatePEMPower spectra and Coherence of Guralps and STS2

We did offline wiener filtering on 3rd August (Elog entry) using only Guralps' channels X and Y.

Here we report the Power spectrum of the 3 seismometers (Guralp1, Guralp2, STS1) during that time.

and also the coherence between the data from different channels of the 3 seismometers.

We see that the STS is less correlated with the two Guralps. We think it is due to the wrong alignment of the STS with the interferometer's axes.

We are going to align the STS and move the seismometers closer to the stacks of the X arm.















  5149   Tue Aug 9 02:34:26 2011 JennyUpdatePSLPZT transfer function measurement

Using a PDA255 on the PSL table, I measured the amplitude response of the NPRO PZT, sweeping from 10kHz to 5 MHz.

I took a run with the laser beam blocked. I then took three runs with the beam unblocked, changing the temperature of the laser by 10 mK between the first two runs and by 100mK between the second and third runs.

At the end of the night I turned off the network analyzer and unplugged the inputs. I'm leaving it near the PSL table, because I'd like to take more measurements tomorrow, probing a narrow bandwidth where the amplitude response is low.

On the PSL table, I'm still monitoring the reflected light from the cavity and the transmitted light through the cavity on the oscilloscope. I'm no longer driving the NPRO temperature with the lock-in.

I closed the shutter on the NPRO laser at the end of the night.

I'll log more details on the data tomorrow morning.

  5150   Tue Aug 9 02:44:32 2011 SureshUpdateSUSETMX free swinging data

I switched off damping to the ETMX and used a reduced version of freeswing-all.csh script (called freeswing-ETMX.csh) to set it swinging.    After about an hour I used the saved template ETMX/2008.08.06.xml to obtain the following plot.



There is something defintely wrong with the side sensor.  It might be the electronics as it also has this problem with it slow channel readings (my previous elog today).



  5151   Tue Aug 9 03:05:05 2011 kiwamuSummaryGeneralweekly report

Summary of the week ending Aug 8th.  Number of elog entries = 56

 + The vent started Wednesday morning
 + Repositioning of the green periscopes and associated mirrors are done.
 + Got both of the green beams coming out from  the chambers
 + Moved the ETMX suspension tower by -8.09 inch (away from vertex)
 + Fixed the alignment of the ETMX CCD mirrors
 + Recovered the X green beam axis for the latest ETMX position

 + oplev centered prior to the vent

 + ETMY_TRANS_QPD didn't respond at all, needs to be fixed
 + Old MZ PD (InGaAs 2mm, @29.5MHz) has been modified for REFL33.
  The 11MHz notch circuit is at the amp side instead of the diode side. This is ready for the installation
 + REFL165 PD has been made from the old 166MHz PD.

 + IPPOS has been sick since 19th of July, 2011
 + IPANG is clipped on a pick-up mirror on the ETMY table. QPD itself is healthy.
 + The spot positions on the MC mirrors were measured prior to the vent.
   The results are almost the same as before within a few percent difference expect for the MC2 yaw.
 + An attenuator, consisting of two HWPs and a PBS, has been installed on the PSL table for the MC low power state.
 + a 10% BS in front of the MCREFL_RFPD was replaced by a perfect reflector for the low power mode.
 + The incident power for MC was decreased to 20 mW
 + The beam axis going to MC was misalgned due to the attenutor.
    Then the beam was aligned by touching two steering mirrors on the PSL table
 + MC is able to be locked in air. The reflection DC goes from 1.4 to 0.13 V when the MC is locked.

 + With the mass-kicking technique, the arm lengths were measured.
   Xarm =  37.5918 m, Yarm = 37.5425 m.

- Green locking
 + Y green beam is aligned to the Y arm
 + Locking of the Y green is not robust, it needs to be revisited

 + Wiener Filtering was applied on the data collected from the X-arm for a duration of 1500 seconds.

- Misc.
 + The hazardous waste people are moving chemicals around outside our door, and have roped off our regular front door.
 + The horizontal trolley drive of the east end crane stopped working. It will be fixed.

  5152   Tue Aug 9 10:15:25 2011 kiwamuUpdateGeneralin-vac work plan today

We will move on to the vertex region today.

The goal of the vertex region work is to get the pick-off beams out the chambers, including POX/Y and POP.

The work will be in parallel to the ETM woks.

The first step will be : lock and align MC with the IR beam.

  5153   Tue Aug 9 11:33:33 2011 kiwamuUpdateSUSRe: ETMX free swinging data

I believe that the 17 Hz broad structure on SIDE is just because of a bad rotational angle of the SIDE OSEM.

The same structure had been observed on the EMTY_UR, and the structure became narrower after we repositioned/rotated the OSEM yesterday.

My guess is that the SIDE OSEM is now in a place where the OSEM is quite sensitive to the bounce mode

and creating the broad structure due to a bi-linear coupling between the bounce mode and low frequency signals.

Quote from #5150

There is something defintely wrong with the side sensor.  It might be the electronics as it also has this problem with it slow channel readings (my previous elog today). 

  5154   Tue Aug 9 13:34:40 2011 NicoleSummarySUSNew Calibration Plots for Photosensors

Here are the new calibration plots for my photosensors. These calibrations were done using a translation stage.

The linear region for the first photosensor appears to be between 15.2mm and 30 mm


The linear region for the second photosensor appears to be between 12.7mm and 22.9mm


The slope for both is -0.32 V/mm  (more precisely, -0.3201 V/mm for PS 1 and -0.3195 V/mm for PS 2)


  5155   Tue Aug 9 15:14:46 2011 KojiUpdateGeneralin-vac work plan today

This morning Kiwamu and I have aligned the MC. Kiwamu aligned the last steering (on the OMC table) to recover the touch last week.
Then I have aligned the MC with MC1 and MC3 as the last steering did not help to get TEM00.


C1:SUS-MC1_PIT_COMM = 2.6587
C1:SUS-MC1_YAW_COMM = 2.7471
C1:SUS-MC2_PIT_COMM = 3.486
C1:SUS-MC2_YAW_COMM = -1.1592
C1:SUS-MC3_PIT_COMM = -1.876
C1:SUS-MC3_YAW_COMM = 1.2829


C1:SUS-MC1_PIT_COMM = 2.7596
C1:SUS-MC1_YAW_COMM = 2.6627

C1:SUS-MC2_PIT_COMM = 3.486
C1:SUS-MC2_YAW_COMM = -1.1592
C1:SUS-MC3_PIT_COMM = -1.697
C1:SUS-MC3_YAW_COMM = 1.2901


We will move on to the vertex region today.

The goal of the vertex region work is to get the pick-off beams out the chambers, including POX/Y and POP.

The work will be in parallel to the ETM woks.

The first step will be : lock and align MC with the IR beam.


  5156   Tue Aug 9 16:00:58 2011 JennyUpdatePSLAmplitude response of PZT


The top plot shows a sweep from 10 kHz to 5 MHz of the ratio of the voltage output of the PD detecting power from the NPRO laser beam and the RF source voltage (the magnitude of the complex transfer function). The black trace was taken with the laser beam blocked. For runs 2 and 3 I changed the laser temperature set point by 10 mK and 100 mK respectively to see if there was a significant change in the AM response. The bottom plots shows runs 2 and 3 compared to run 1 plotted in dB (to be explicit, i'm plotting 10 times the base 10 log of the magnitude of the ratio of two complex transfer functions). Changing the temperature seems to have only a minor effect on the output except at around 450kHz, where the response has a large peak in run 1 and much smaller peaks in runs 2 and 3. 

The traces in the top plot consist of 16 averages taken with a 300Hz IF bandwidth, 15 dBm source power (attenuated with a 6 dB attenuator) and with 20dB attenuation of the input power from the PD.

Next I'm going to probe a narrow band region where the response is low (2.0MHz or 2.4MHz perhaps) and choose a bandwidth for the dither frequency for the PDH locking.

Attachment 1: AMresponsePZT.png
  5157   Tue Aug 9 16:21:59 2011 Manuel, IshwitaUpdateWienerFilteringFirst results of our simulations

We did the simulation of the stacks by defining a transfer function for one stack (green plot) and another similar transfer function for the other stack.

We simulated the ground motion by filtering a white noise with a low pass filter with a cutoff frequency at 10Hz. (blue plot) (the ground motion for the 2 stacks are completely uncorrelated)

We simulated the electronic white noise for the seismic measurements. (black plot)

We filtered the ground motion (without the measurements electronic noise) with the stack's transfer function and subtracted them to find the mirror response (red plot), which is the target signal for the wiener filter.

We computed the static wiener filter with the target signal (distance between the mirrors) and the input data (seismic measurements = ground motion + electronic noise).

We filtered the input and plotted the output (light blue plot).

We subtracted the target and the output to find the residual (magenta plot).

We didn't figure out why the residual is above the electronic noise only under ~6hz. We tried to increase and decrease the electronic noise and the residual follows the noise still only under ~6Hz.

It also shows that the residues are above the target at frequencies over 20Hz. This means that we are injecting noise here.


We tried to whiten the target and the input (using an high pass filter) to make the wiener filter to care even of higher frequencies.

The residues are more omogeneously following the target.

We also plotted the Wiener filter transfer function without making whitening and with making whitening. It shows that if we do whitening we inject no noise at high frequency. But we loose efficency at low frequencies.



We shouldn't care about high frequency, because the seismometers response is not good over 50Hz. So, instead of whitening, we should simply apply a low pass filter to the filter output to do not inject noise and keep a good reduction at low frequencies.


  5158   Tue Aug 9 16:40:12 2011 steveUpdateGeneralclean room coat counts

I measured the particles coming off of new- unused clean room coat. Tyvek, Convertors, Allegiance #9393 measured  10 counts of 0.3 micron at 1 minute and 0 count at 7 minute.

The 0.5 micron size  measured 0 at both times. Jenne's used coat measured 20 counts of 0.3 micron  and 0 counts for 0.5 micron at 1 minute. ( counts / cf- min)

The HEPA tent background is consistently 0 when it's CP STAT 100 curtains are closed.

Attachment 1: P1080155.JPG
  5159   Tue Aug 9 16:54:47 2011 steveUpdateVACscratch on vac door

Jenne found a big scratch on the north vac door of ITMY. Fortunately it does not reach the inner annulos 0 -ring seal.

This is precisely what we have to avoid to preserve our vacuum system!


Attachment 1: P1080152.JPG
  5160   Tue Aug 9 19:53:56 2011 NicoleSummarySUSWeekly Summary

This week, I have finished assembling everything I need to begin shaking. I built an intermediary mounting stage to mount the TT suspension base to the horizontal sliding platform, finished assembling the second photodiode, finished assembling the photosensor circuit box, and calibrated the two photosensors. Today I built a platform/stage to mount the photodiodes so that they are located close enough to the mirror/suspension that they can operate in the linear range.  Below is an image of the set-up.


The amplifer that Koji fixed is acting a bit strange again...It is sometimes shutting off (Apparently, it can only manage to do short runs ~ 1minute? That should be enough time?).

The set-up is ready to begin taking measurements.

  5161   Wed Aug 10 00:11:39 2011 jamieUpdateSUScheck of input diagnolization of ETMX after OSEM tweaking

Suresh and I tweaked the OSEM angles in ETMX yesterday.  Last night the ETMs were left free swinging, and today I ran Rana's peakFit scripts on ETMX to check the input diagnolization:


It's well inverted, but the matrix elements are not great:

       pit       yaw       pos       side      butt
UL    0.3466    0.4685    1.6092    0.3107    1.0428
UR    0.2630   -1.5315    1.7894   -0.0706   -1.1859
LR   -1.7370   -1.5681    0.3908   -0.0964    0.9392
LL   -1.6534    0.4319    0.2106    0.2849   -0.8320
SD    1.0834   -2.6676   -0.9920    1.0000   -0.1101

The magnets are all pretty well centered in the OSEMS, and we worked at rotating the OSEMS such that the bounce mode was minimized.

Rana and Koji are working on ETMY now.  Maybe they'll come up with a better procedure.

  5162   Wed Aug 10 00:21:10 2011 jamieUpdateCDSupdates to peakFit scripts

I updated the peakFit routines to make them a bit more user friendly:

  • modified so that any subset of optics can be processed at a time, instead of just all
  • broke out tweakable fit parameters into a separate parameters.m file
  • added a README that describes use

These changes were committed to the 40m svn.

  5163   Wed Aug 10 01:40:40 2011 KojiUpdateSUSETMY exploration

[Rana Koji Jenne Jamie]

- The situation of the ETMY suspension is improved.
- The damping servos except for Pitch are now functional.
- We intentionally turned off the damping servos for the matrix measurements.

- Opened the light door of the ETMY chamber.

- We set up the CDS SUS lockin:

        Excite UL/UR/LL/LR equally [by setting the output matrix (1, 1, 1, 1, 0)] at 3.12Hz with 2000 cnts
        Put the OSEM PD outputs into lockin one by one. For the image rejection, 0.1Hz 4th order LPF has been used though we like to use a faster settling LPF.

- Found only UL was responding to the excitation. After fitzing with the cables and connectors, it was found that the DAC card was loose from the bus.
  By pushing the card the responses have been back. [Note we had the reboot of c1iscey almost at the same time.]

- Checked the response in the I channel of the lockin.
        UL -8ish / UR +7ish / LR +5ish / LL +2ish

- Tweaked LL sensor to get better response ==> in vain. Decided to move the lower OSEM plate for the better positioning of the LR/LL.
- Got reasonable (+5ish) response for LL.

- Confirmed that the POS/YAW/SIDE damping works with positive gains. PITCH did not work with the negative gain (but that could be a good sign.)

- Let the suspension freely swinging for a while (~30min). Checked the side/pos separation. They are not perfect but seemed diagonalizable.

- Closed the light door.

- Jenne will make a better kick/free-swing test later.

  5164   Wed Aug 10 02:29:38 2011 JenneUpdateSUSETMY exploration


- Jenne will make a better kick/free-swing test later.

 02:27am, ran the new freeswinging-ifo.csh script.  It's just a copy of freeswinging-all.csh, but it doesn't include the MC mirrors, since Suresh and Kiwamu are still working.  

Now we have copies of the script for -all, -mc, -ifo to cover the various sections of the suspended interferometer.

  5165   Wed Aug 10 02:40:40 2011 JennyUpdatePSLDither freq for PZT chosen: 2.418 MHz

I've finished using the network analyzer to characterize find a dither frequency for driving the PZT to use in my PDH locking. I found a region in which the amplitude response of the PZT is low: The dip is centered at 2.418 MHz. Changing the NPRO laser temperature by 100mK has no significant effect on the transfer function in that region. I will post plots tomorrow.

I'm finished with the network analyzer. It is unplugged, and the cart is still near the PSL table. (I'll roll it back tomorrow when it won't disturb interferometer locking).

I closed the shutter on the NPRO at the end of the night.

Tomorrow I plan to put together the fast locking setup. I'll drive the PZT at 2.418 MHz. More details to come tomorrow.

  5166   Wed Aug 10 07:59:33 2011 steveUpdateSUSthis is too dam nice


Suresh and I tweaked the OSEM angles in ETMX yesterday.  Last night the ETMs were left free swinging, and today I ran Rana's peakFit scripts on ETMX to check the input diagnolization:


It's well inverted, but the matrix elements are not great:

       pit       yaw       pos       side      butt
UL    0.3466    0.4685    1.6092    0.3107    1.0428
UR    0.2630   -1.5315    1.7894   -0.0706   -1.1859
LR   -1.7370   -1.5681    0.3908   -0.0964    0.9392
LL   -1.6534    0.4319    0.2106    0.2849   -0.8320
SD    1.0834   -2.6676   -0.9920    1.0000   -0.1101

The magnets are all pretty well centered in the OSEMS, and we worked at rotating the OSEMS such that the bounce mode was minimized.

Rana and Koji are working on ETMY now.  Maybe they'll come up with a better procedure.


  5167   Wed Aug 10 11:22:55 2011 SureshUpdateIOOMC A2L alignment

[Kiwamu, Suresh]

We attempted to minimise the A2L coupling in the MC mirrors (centering the beam spot on the actuation node on each optic).  While it was easy to minimise the coupling in the pitch for all the three optics and yaw of MC2, the yaw alignment of MC1 and MC3 proved to be difficult.  For one the adjustment required was quite large, so much so that PSL alignment into the MC is often lost during this adujstment.  We had to align the PSL coupling several times in order to proceed.   And the MC settles into a new position when the MC-PSL servo loop was disturbed by random denizens in the lab.  Requiring us to start over again.

Kiwamu wrote a script to measure the MC(optic)(Pitch/yaw) -> Lockin(#1 to #6) matrix.  Inverting this matrix gave us the linear combination of the offsets to put on the MC# PIT/YAW  inorder to minimise a specific Lockin output.  However the cross couplings were not completely eliminated.  This made it very hard to predict what a given set of offsets were going to do to the Lockin outputs.

Net result:  the spots are centered in vertical direction (pitch) but not in the horizontal (yaw)

Day time tasks have started so I am quitting now.

  5168   Wed Aug 10 12:28:22 2011 Ishwita , ManuelUpdatePEMAA board gain

We used a function generator, an oscilloscope and the Data Viewer to check the gain of the new AA board (used for the seismometers). Putting a sine wave of 0.3V (using a function generator) to the AA board, we could see about 500 counts in the Data Viewer. The calibration of the ADC is 214 counts/volt, so the AA board gives to the ADC an output of 0.03V. This proves that the AA board has a gain of 0.1. Guralp1 and STS1 (Bacardi), both have a gain of 10 now, that balance the AAboard gain of 0.1. If we consider the gain of AA board in our calibrated power spectrum plot of seismic signals from Guralp1 and STS1 (Bacardi), we get the following plot:


  5169   Wed Aug 10 12:32:09 2011 NicoleSummarySUSWeekly Summary Update

Last night, I attached a metal plate to the Vout faceplate of my photosensor circuit box because the BNC connection terminals were loose. This was Jamie's suggestion to establish a more secure connection (I had originally drilled holes for the BNCs that were much too large).


I have also fixed the mechancial set-up of my shaking experiment so that the horizontal sliding platform does not interfere with the photodiode mounting stage. Koji pointed out last night that in the full range of motion, the photodiode mounting stage interferes with the movement of the sliding platform when the platform is at its full range.


I have began shaking. I am getting a problem, as my voltage outputs are just appearing a high-frequency noise.

  5170   Wed Aug 10 12:33:34 2011 Manuel, IshwitaSummaryPEMWeekly summary

We got the results of the wiener filtering simulations (Elog Entry)

We got the power spectra and coherence of the seismic noise measurements from GURALPs and STS seismometers (Elog Entry)

We tried to whiten the target and the input signal for the computation of the wiener filter for the real data, but the results are unsatisfactory. We should not care about high frequencies in wiener filter computation so we will just filter them off in the filter output with a low pass filter.

We just found the right gain for the system seismometer-AAboard-ADC (Elog Entry)

  5171   Wed Aug 10 13:52:23 2011 Manuel , IshwitaUpdatePEMMoving Seismometers

We turned off the power of the seismometers and moved the Guralp1 close to the STS. Both are now situated below the center of the mode cleaner vacuum tube.

We oriented the X axis of the STS & Guralp1 along the X axis of the interferometer. Then we turned on the power again, but the STS channels don't give any signal. We think this is, because we didn't push the auto zero button.

  5172   Wed Aug 10 14:27:39 2011 Ishwita , ManuelUpdatePEMCalibration of Guralp and STS2

ADC: 216counts = 4V Hence, calibration of ADC is 214counts/V.

Gain of the AA board, g1 = 0.1


Sensitivity = 800 V/ms-1

214 counts/V x 800  V/ms-1 = 13107200 counts/ms-1 -----> 7.6294e-08 ms-1/count

Gain, g2 = 10

Calibration = 7.6294e-08 ms-1/count x g1 x g2 = 7.6294e-08 ms-1/count


Sensitivity = 1500 V/ms-1

214 counts/V x 1500  V/ms-1 = 24576000 counts/ms-1 -----> 4.069e-08 ms-1/count

Gain of the STS electronic breakout box, g3 = 10

Calibration = 4.069e-08 ms-1/count x g1 x g3 = 4.069e-08 ms-1/count

  5173   Wed Aug 10 14:30:55 2011 kiwamuUpdateIOORe: MC A2L alignment

I modified a set of the automated MC locking scripts which are dedicated for the low power MC.

Currently there are three scripts like the usual MC locking scripts:

(1)mcup_low_power, (2) mcdown_low_power and (3) autolockMCmain40_low_power.

I ran those scripts on op340m as usual and so far they are running very well. The lock acquisition is quite repeatable.

I hope theses scripts always bring the lock condition to the same one and hence the LOCKIN signals don't change by every lock.


- To run the script

  log into op340m and run autolockMCmain40m_low_power

Quote from #5167

And the MC settles into a new position when the MC-PSL servo loop was disturbed by random denizens in the lab.  Requiring us to start over again.


  5174   Wed Aug 10 14:35:39 2011 ranaUpdatePEMCalibration of Guralp and STS2

I'm pretty sure that don't have any ADC's with this gain. It should be +/- 10V for 16 bits. 

  5175   Wed Aug 10 15:17:39 2011 Ishwita, ManuelUpdatePEMCalibration of Guralp and STS2


I'm pretty sure that don't have any ADC's with this gain. It should be +/- 10V for 16 bits. 

Jenne told us that the ADC was +/- 2V for 16 bits so our calibration is wrong. Since, the ADC is +/- 10V for 16 bits we need to change our calibration and now we can also use the purple STS breakout box.

  5176   Wed Aug 10 15:39:33 2011 jamieUpdateSUScurrent SUS input diagonalization overview

Below is the overview of all the core IFO suspension input diagonalizatidons.

Summary: ITMY, PRM, BS are really bad (in that order) and are our top priorities.


I had originally put the condition number of the calculated input matrix (M) in the last column.  However, after some discussion we decided that this is not in fact what we want to look at.  The condition number of a matrix is unity if the matrix is completely diagonal.  However, even our ideal input matrix is not diagonal, so the "best" condition number for the input matrix is unclear.

What instead we do know is that the matrix, B, that describes the difference between the calculated input matrix, M, and the ideal input matrix, M0: should be diagonal (identity, in fact):

M = M0 B

B should be diagonal (identity, in fact), and it's condition number should ideally be 1.  So now we calculate B-1, since it can be calculated from the pre-inverted input matrix:

B-1 = M-1 * M0

From that we calculate cond(B) == cond(B-1).

cond(B) is our new measure of the "badness" of the OSEMS.

new summary: ITMY, PRM, BS are really bad (in that order) and are our top priorities.


 cond(M) cond(B)
 PRM PRM.png        pit     yaw     pos     side    butt
UL   -2.000  -2.000  -2.000  -0.345   2.097 
UR   -0.375  -0.227  -0.312  -0.060   0.247 
LR    1.060   1.075   0.971   0.143  -0.984 
LL   -0.565  -0.698  -0.717  -0.141   0.672 
SD    1.513   1.485   1.498   1.000  -1.590
 75.569 106.756
 SRM SRM.png  

      pit     yaw     pos     side    butt
UL    0.791   1.060   1.114  -0.133   1.026 
UR    1.022  -0.940   1.052  -0.061  -1.027 
LR   -0.978  -0.987   0.886  -0.031   0.903 
LL   -1.209   1.013   0.948  -0.103  -1.043 
SD    0.286   0.105   1.249   1.000   0.030

 2.6501 3.90776
 BS  BS.png  

      pit     yaw     pos     side    butt
UL    1.420   0.818  -0.069   0.352   1.038 
UR    0.276  -1.182   1.931  -0.217  -0.905 
LR   -1.724  -0.274   1.940  -0.254   0.862 
LL   -0.580   1.726  -0.060   0.315  -1.194 
SD    0.560   0.171  -3.535   1.000   0.075 

9.8152 7.28516
ITMX ITMX.png       pit     yaw     pos     side    butt
UL    0.437   1.015   1.050  -0.065   0.714 
UR    0.827  -0.985   1.129  -0.221  -0.957 
LR   -1.173  -1.205   0.950  -0.281   1.245 
LL   -1.563   0.795   0.871  -0.125  -1.084 
SD   -0.581  -0.851   2.573   1.000  -0.171 
 4.08172 4.69811
 ITMY  ITMY.png  

      pit     yaw     pos     side    butt
UL    0.905  -0.884  -0.873   0.197   0.891 
UR   -1.095   1.088   1.127  -0.252  -1.115 
LR   -0.012  -0.028   0.002   0.001   0.030 
LL    1.988  -2.000  -1.998   0.451   1.964 
SD    4.542  -4.608  -4.621   1.000   4.517 

 801.453 774.901
 ETMX  ETMX.png        pit     yaw     pos     side    butt
UL    0.344   0.475   1.601   0.314   1.043 
UR    0.283  -1.525   1.786  -0.071  -1.181 
LR   -1.717  -1.569   0.399  -0.102   0.938 
LL   -1.656   0.431   0.214   0.283  -0.837 
SD    0.995  -2.632  -0.999   1.000  -0.110 
 4.26181 4.33518
 ETMY  ETMY.png        pit     yaw     pos     side    butt
UL   -0.212   1.272   1.401  -0.127   0.941 
UR    0.835  -0.728   1.534  -0.101  -1.054 
LR   -0.953  -1.183   0.599  -0.066   0.827 
LL   -2.000   0.817   0.466  -0.092  -1.177 
SD   -0.172   0.438   2.238   1.000  -0.008 
 4.04847 4.33725


  5177   Wed Aug 10 18:25:45 2011 JenneUpdateSUSETMY mini-update

[Jenne, Jamie]

ETMY is now in its new nominal position, according to the rails that Kiwamu put in the other day.  OSEM voltages are all centered, and the magnets looked pretty well centered in the OSEM bores.  We're taking data for some free swinging spectra, to check the decoupling. 

Next up: Align Y-green to the arm, then move on to fixing the other optics that Jamie pointed out.

  5178   Wed Aug 10 19:18:26 2011 NicoleSummarySUSFixed Reflective Photosensors; Recalibrated Photosensor 2

Thanks to Koji's help, the second photosensor, which was not working, has been fixed. I have re-calibrated the photosensor after fixing a problem with the circuit.  I have determined the new linear region to lie between 7.6 mm and 19.8mm. The slope defining the linear region is -0.26 V/mm (no longer the same as the first photosensor, which is -0.32 V/mm).


Here is the calibration plot.


  5179   Wed Aug 10 20:40:17 2011 JennyUpdatePSLPDH locking: got an error signal

I ended up choosing a different dither frequency for driving the NPRO PZT: 230 kHz, because the phase modulation response in that region is higher according to other data taken on an NPRO laser (see this entry). At 230 there is a dip in the AM response of the PZT.

I am driving the PZT at 230 kHz and 13 dBm using a function generator. I am then monitoring the RF output of a PD that is detecting light reflected off the cavity. (The dither frequency was below the RF cutoff frequency of the PD, but it was appearing in the "DC output", so I am actually taking the "DC output" of the PD, which has my RF signal in it, blocking the real DC part of it with a DC block, and then mixing the signal with the 230kHz sine wave being sent to the PZT.

I am monitoring the mixer output on an oscilloscope, as well as the transmission through the cavity. I am sweeping the laser temperature using a lock in as a function generator sending out a sine wave at 0.2 V and 5 mHz. When there is a peak in the transmission, the error signal coming from the mixer passes through zero.

My next step is to find or build a low pass filter with a pole somewhere less than 100 kHz to cut out the unwanted higher frequency signal so that I have a demodulated error signal that I can use to lock the laser to the cavity.


  5180   Wed Aug 10 22:47:22 2011 ranaSummaryVACVacuum Workstation (linux3) re-activated

For some reason the workstation at the vac rack was off and unplugged. Nicole and I plugged its power back in to the EX rack.

I turned it on and it booted up fine; its not dead. To get it on to the network I just made the conversion from 131.215 to 192.168 that Joe had done on all the other computers several months ago.

Now it is showing the Vacuum overview screen correctly again and so Steve no longer has to monopolize one of the Martian laptops over there.

  5181   Thu Aug 11 02:16:57 2011 JenneUpdateGreen LockingY-green aligned and flashing

[Jenne, with ample supervision by Kiwamu and Suresh]

Y-green was aligned, and is now flashing.  The ETMY trans camera was very helpful for this alignment.  I didn't end up needing to use a foil aperture. 

Kiwamu and Suresh had just closed up the IOO doors, so we don't know yet where it's hitting on the PSL table (if the beam is making it that far).  Tomorrow we'll look at ITMY to see if the green beam is centered there, and if it's coming out to the PSL table.

  5182   Thu Aug 11 04:45:07 2011 SureshUpdateIOOAligning the 1064nm beam with the in-vacuum pzt's

[Kiwamu, Suresh]

We worked on the beam path from MC to BS this evening. 

After the beam spots on MC1 and MC3 were close to the actuation nodes (<1mm away) we checked the beam position on the Faraday Isolator (FI) to make sure that it is passing through both the input and output apertures without clipping.  The beam is slightly displaced (by about half a beam diameter) downwards at the input of the FI.  The picture below is a screen shot from the MC1 monitor while Kiwamu held an IR card in front of the FI.



We then proceeded to check the beam position on various optical elements downstream.  But first we levelled the BS table and checked to see if the reflection from PJ1 (1st Piezo) is landing on the MMT1 properly.  It was and we did not make any adjustment to PJ1.  However the reflection from MMT1 was not centered on MMT2.  We adjusted the MMT1 to center the beam on it.  We then adjusted MMT2 to center the beam on PJ2.  At this point we noticed that the spot on IPPO (pick off window)  was off towards the right edge.  When we centered the beam on this it missed the center of the PRM.  In order to decide what needs to be moved, we adjusted PJ2 such that the beam hits the PR2, bounces back to PR3, and becomes co-incident with the green beam from X-arm on the BS.  Under this condition the beam is not in the center of PRM and nor is it centered on IPPO.  In fact it is being clipped at the edge of the IPPO. 

It is clear that both IPPO and the PRM need to be moved.  To be sure that the beam is centered on PR2 we plan to open the ITMX chamber tomorrow.

  5183   Thu Aug 11 06:45:14 2011 NicoleSummarySUSShaking Testing

Koji and I have finished shaking the table for the first round of measurements (horizontal shaking). We have cleaned up the lab space used.

The FFT Analyzer has been put back to its position at the back side of the rack (near the seismometers).


I will calibrate the photosensor for the suspension frame and piece together/analyze/produce graphs of the data today. If everything is fine (the measurements are fine) and if there is a chance, we hope to shake the TT suspension vertically.

  5184   Thu Aug 11 08:29:28 2011 steveUpdateComputersdataviewer at Rosalba

I'm having this problem with DTV every morning at Rosalba only. It wants to start with a negative GPS time and it can not connect to the frame builder.

Normally after a few time of starting it, it will work.

Attachment 1: gpsfmb.png
  5185   Thu Aug 11 09:39:25 2011 Ishwita, ManuelUpdatePEMCalibration of Guralp and STS2



I'm pretty sure that don't have any ADC's with this gain. It should be +/- 10V for 16 bits. 

Jenne told us that the ADC was +/- 2V for 16 bits so our calibration is wrong. Since, the ADC is +/- 10V for 16 bits we need to change our calibration and now we can also use the purple STS breakout box.

 New calibration for Guralp:

ADC: 216counts = 20V Hence, calibration of ADC is (215x0.1) counts/V.


Sensitivity = 800 V/ms-1

(215 x 0.1) counts/V x 800  V/ms-1 = 2621440 counts/ms-1 ----->  3.8147e-07 ms-1/count

Calibration = 3.8147e-07 ms-1/count

Using the above calibration we obtain the following plot:


When we compare this plot with the old plot (see here) we see that in our calibration, we have got a factor of 10 less than the old plot. We do not know the gain of the Guralp. If we assume this missing 10 factor to be the gain of Guralp then we can get the same calibration as the old plot. But is it correct to do so?

  5186   Thu Aug 11 10:56:08 2011 Ishwita, ManuelUpdatePEMMoving Seismometers


We turned off the power of the seismometers and moved the Guralp1 close to the STS. Both are now situated below the center of the mode cleaner vacuum tube.

We oriented the X axis of the STS & Guralp1 along the X axis of the interferometer. Then we turned on the power again, but the STS channels don't give any signal. We think this is, because we didn't push the auto zero button.

 After pressing the auto-zero button (a lot of times) of the STS breakout box & aligning the bubble in the STS, we could finally get data from STS (Bacardi). So, now STS2 (Bacardi - Serial NR. 100151) is working!

ELOG V3.1.3-