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ID Date Author Type Category Subject
  5046   Wed Jul 27 15:18:50 2011 kiwamuSummaryGeneralschedule

The vent will start from 1 st of August ! !

  5045   Wed Jul 27 12:31:47 2011 Manuel, IshwitaSummaryPEMWeekly summary

We kept reading about digital filtering

We tested the seismometer last friday

Jan came and tested again the seismometer last monday

We wrote a simulation of the stacks transfer functions, and of the distance between the mirrors.

 

  5044   Wed Jul 27 12:19:19 2011 NicoleSummarySUSWeekly Summary

Since last week, I've been working on building the photosensor head and have been making adjustments to my photosensor circuit box.

Changes to photosensor circuit (for box):

1) Last week, I was reading in the two signals from the two heads through a single input. Now there are two separate inputs for the two separate photosensors

2)During one of my many voltage regulator replacements, I apparently used a 7915 voltage regulator instead of a 7805 (thanks, Koji, for pointing that out! I never would have caught that mistake X___X)

3)I was powering my 5V voltage regulator with 10V...Now I'm using 15 V (now I only need 1 power supply and 3 voltage input plugs)

I have also began assembling my first photosensor head. Here is what I have so far:

sensorhead.JPG

 

Here is what needs to be done still for the photosensor head

I need to find four Teflon washers and nuts to rigidly attach the isolated PCB (PCB, Teflon sheet combination) to the box. I already have the plastic screws in (I want to use plastic and Teflon for electrical isolation purposes, so as to not short my circuit).

I need to attach the sheath of my signal cable to the box of the photosensor head for noise reduction (plan: drill screw into photosensor head box to wrap sheath wires around)

I need to attach the D-sub to the other end of my signal cable so that it can connect to the circuit box. So far, I only have the D-sub to connect the cable to my photosensor head

Yesterday, Suresh helped to walk me through the photosensor box circuit so that I now understand what voltages to expect for my circuit box trouble-shooting. After this lesson, we figured out that the problem with my photosensor box was that the two op-amps were saturated (so I fixed the feedback!). After replacing the resistor, I got the LED to light up! I still had problems reading the voltage signals from the photodiodes. I was reading 13.5V from the op amp output, but Koji explained to me that this meant that I was too close to saturation (the photodiodes were perhaps producing too much photocurrent, bringing the output close to saturation). I switched the 150 K resistor in the feedback loop to a 3.4K resistor and have thus successfully gotten displacement-dependent voltage outputs (i.e. the voltage output fluctuates as I move my hand closer and farther from the photosensor head). 

Now that I have a successful circuit to power and read outputs from one photosensor, I can begin working on the other half of the circuit to power the other photosensor! 

sensorcircuit.JPG

  5043   Wed Jul 27 10:10:12 2011 steveUpdatePSLlocking status

 80 days: PMC is drifting

Attachment 1: 80dpmcMC.jpg
80dpmcMC.jpg
  5042   Wed Jul 27 10:04:29 2011 SureshUpdateIOOWFS transfer function measurements

This is part of the WFS activity.  So far I have completed the following tasks:

1)  I fixed the MEDM screens up to a point where they can be used for locking.  There are still some buttons which invoke non-existing screens and some blank fields.  But the basic filter banks and input  and output matrices are fixed.

2) I copied all the old filter banks into the new screens both in the WFS head and in the WFS Master, where the servo filters are located.  The I and Q filter banks in the WFS heads have been switched on.

3) I <=> Q phase settings in the WFS head for each quadrant:  We have assumed that the I and Q are orthogonal so D=90 for all cases.  I set the R phase to minimise the signal in all the Q lines.  So the signal is largely in the I phase.  I used Sine Response feature in DTT while supplying an excitation signal to MC2_ASCPIT_EXC.  At times I used the YAW instead of PIT if I did not get enough coherence.  This was set manually by watching the Q phase signal and minimising that by adjusting the R angle.  It was in general possible to get this correct to a deg.   There are several old scripts to do this in the MC/WFS but they do not work since most of them are based on the ezlockin or ezcademod functions.    I will try to fix the ezWFS1phase and ezWFS2phase scripts to automate this.  Some channel names have to be changed in these.

4) I measured the transfer function between the mirror motions [(MC1, MC2, MC3) x (PIT, YAW)] and the sensor DoF [(WFS1, WFS2) x (PIT, YAW)].  The measurements are reported below.  The plan is to invert this matrix and use it as the Out_Matrix.

WFS_TF_Phase_Sheet1.png

I list here the various steps I took in making this measurement.

a) Set the DC offsets on the individual quadrants to zero using an old script (which I updated with the new channel names).  The script is called McWFS_dc_offsets and is located in the $scripts$/MC/WFS directory.   Note that before doing this the PSL shutter was closed.  This script sets a basic EPICS parameter called AOFF for each channel.  These are listed in cvs/cds/caltech/target/c1iool0 .

b) Then the PSL beam into the MC was steered to optimise coupling into MC (described in my earlier post today).  This is because we use the input beam as a reference while setting up the WFS.

c) Unlock the MC and center the directly reflected beam from the MC on the WFS.  We use the DC monitors on the C1IOO_WFS_QPD.adl screen to center the spot on the WFS head. 

d) Then used the WFSoffsets script to set the offsets in the I and Q filter banks to zero.  This script uses the ezcaservo to look at the OUT16 channels and zeroes them by setting an appropriate offset.  I took care to switch off all slow filters in the I and Q filter banks before this operation was carried out .  Only the 60Hz comb filter was on.

e) Opened the PSL shutter and relocked the MC

f) Then I measured the transfer co-efs by oscillating the optic (exciting a specific degree of freedom) and observing the response in the WFS sensor degrees of freedom.   These are tabulated above.

Next

   I plan to use this matrix and prepare the Output matix and then close the WFS servo loops. 

 

 

  5041   Wed Jul 27 08:59:10 2011 SureshUpdateLSClocking status

 I had to realign PSL beam into the MC in order to reobtain the MC lock.  We lost lock at sometime around 8:30 AM on Tuesday.  See attached trend data for MC_RFPD_DCMON. 

The is the second time this week that I had to do this when we were unable to obtain the MC lock.  On both occassions the zig-zag at the end of the PSL table was tweaked to minimise the MC_RFPD_DCMON.

MC_RFPD_DCMon.png

 We have been using the MC as a Beam Axis Reference.  And therefore we are adjusting the PSL beam to maximise coupling into MC.  However if MC's beam axis has shifted, then would it not be best to use the pzt's to re-obtain coupling into the arm cavities? 

Quote from #5040

Beam axis:

 I guess that the beam axis has changed a lot to the horizontal direction.
The beam spots on the REFL and AS camera looked off-centered by a size of the spot.
The beam axis has to be well-aligned before the vent.

  5040   Wed Jul 27 01:58:23 2011 kiwamuUpdateLSClocking status

Through some locking exercise I found that several things are degrading.

Remember the interferometer is like a cat, so we have to feed and take care of her everyday. (Otherwise the cat will be dead !)

 

Beam axis:

 I guess that the beam axis has changed a lot to the horizontal direction.
The beam spots on the REFL and AS camera looked off-centered by a size of the spot.
The beam axis has to be well-aligned before the vent.

 

Locking of the Arms :

 didn't lock at all. It could be a problem of the demodulation phase on AS55.
Also the TRY camera looked pretty much off-centered. The spot is already getting out from the field of view.
We have to fix this issue, otherwise we cannot align the beam axis.
 
 

Locking of PRM :

 Sort of okay, I was able to lock both MICH and PRCL although I had to flip the sign of the MICH control gain due to the demod-phase change.
The suspensions don't look healthy. The beam spots on the REFL and AS camera move a lot even without any length feedback.
It means some of the suspensions are shaky.
  5039   Wed Jul 27 01:57:28 2011 SonaliUpdateGreen LockingWeekly Summary

1. I have used the PMC  trans beam in my set-up as the required PSL beam.

2. I have superposed the ETMX-Fibre output with the PSL beam on the PSL table.

3. I have used suitable beam splitters and lens to match the power and the  sizes of the overlapping beams and have aligned them to the optimum.

4. A lens having f=7.6 cms is used to focus the beam into the PD.

5. Initially, I used the broadband 1611 NewFocus PD to find the IR beat signal by scanning the oven temperature. (using the digital sitemap controls.)

6. I checked the previous elog entries by Suresh and Koji on the green beat signal they had worked on and used their data to get an idea of the temperature range of the oven where I could obtain a beat.

7. I obtained peaks at three different temperatures as had been noted previously and set the temperature so that I am now sitting in the middle stable regime.

8. Then I switched to the 1811 100 MHz PD as it has a larger gain. It has a saturation power of 100 microWatts. The input power at the PD is measured to be 80 microWatts.

9. I was having trouble getting a clean peak due to presence of many harmonics as seen on the spectrum analyser. This happened because there was too much power incident on the PD which led to arising of non-linearity giving rise to harmonics.

10.To reduce the power entering the PD, I put in a ND 1.0 Filter just before the beam enters the PD and obtained a clean signal.

11. I will use  the frequency counter tomorrow to check the resonant frequency and try to connect the output to acquire a digital signal.

12. Otherwise I will proceed to build a Mixer Frequency Discriminator.

13. After the feed-back loop is completed, I will proceed to compare the frequency-noises of the green-beat lock and the IR-beat lock.

  5038   Tue Jul 26 21:11:40 2011 haixingSummaryElectronicsAA filter tolerance analysis

Given this new setup, we realized that the previous tolerance analysis is incorrect. Because the uncertainty in the capacitance value
does not affect the common mode rejection, as two paths share the same capacitor. Now only the imbalance of two resistors is relevant.
The error propagation formula goes as follows:


We require that the common-mode rejection error at low frequency up to 8kHz, namely
with , one can easily find out that the corner frequency needs to be around 24kHz.


 

  5037   Tue Jul 26 11:38:45 2011 steveUpdateSUSETMY bias checked

 

 I test drove ETMY biases.

PITCH  worked well in slow and fast modes. Slow drive was from the IFO alignment screen C1:SUS-ETMY_PIT_COM and

the fast one from C1:SUS-ETMY_ASCPIT_OFFSET

YAW did not.  It was always diagonal. It was  specially bad with the fast drive. I compared them with ETMX. ETMX yaw is diagonal a little bit too.

The OPLEV return spots on the qpd ETMX and ETMY are big 5-6 mm diameter. The ETMY spot has weird geometry to qpd.

  5036   Tue Jul 26 09:01:53 2011 JennyUpdateComputer Scripts / ProgramsMode matching

I found a mode matching solution to match the beam coming to the PSL table from the AP table so that I can lock the laser beam coming onto the PSL table to the reference cavity on the table. I determined that at the polarizing beam splitter, I want a beam with a q=(147+25.1i)mm (w0=58mm). This came from applying the ABCD matrices for three distances,

  • d1=693 mm,
  • d12=660.4 mm, and
  • d2=393.7 mm, separated
  • an f=229.1 mm planoconvex lens and
  • an R=300 mm curved mirror.

to a beam with q0 = 406.4i mm (w0=0.371 mm at the PMC).

I obtained the following mode matching solution, which I will try to implement on the PSL table:

The beam I have has waist 0.281 mm at -2.74 m (I set my origin at the polarizing beam splitter--the spot where I want my beam to match the beam coming from the PMC, so all waists are behind that point). These numbers  come from the beam-profiling and MATLAB-fitting I did (see 5015).

The solution I chose was: f = 1145.6 mm at -0.95 m and f = 572.7 mm at -0.62 m. This may need to be changed however, if I need to add in some beam steering, which would increase the path length traveled by the beam.

modematchparameters.png modematchpic.png

 

  5035   Tue Jul 26 03:15:52 2011 JenneUpdateLockingLatest MICH noise budget

[Jenne, Rana]

We had another look at the MICH noise budget tonight. Rana has verified that my techniques / math aren't too ridiculous. 

In the first attachment, you'll notice that the MICH noise is waay above the shot noise of 1mW on the beam splitter.  We don't know why.  One problem is that the modulation depth of the 55MHz is too low by ~a factor of 10.  Kiwamu and his magical resonant circuit are working on fixing this.  This will not, however, fix the huge discrepancy here.  More investigation and meditation is required!  For this measurement, the whitening gain of AS55 was set to 42dB for both I and Q.

In the 2nd attachment, the PSL shutter is closed, so all of these are dark measurements of AS55.  (The input matrix on the LSC screen is AS55Q * 1 -> MICH_IN1, so they're the same).  All we've done is change the whitening gain before the ADC.  For 0dB and 9dB, you can see that the low freq noise didn't change - here we're still limited by the ADC noise.  With 21dB and 42dB we're clear of the ADC, so either is fine.  Unfortunately, the high freq stuff when the loop is on matches up with the high freq part of the dark noise, so that's part of the problem....

Attachment 1: MICHnoise_shotNoise_25July2011.pdf
MICHnoise_shotNoise_25July2011.pdf
Attachment 2: MICH_darkNoise_whiteningGainChanging_25July2011.pdf
MICH_darkNoise_whiteningGainChanging_25July2011.pdf
  5034   Mon Jul 25 23:43:20 2011 ManuelHowToElectronicsManual for 1201 Low Noise Preamplifier

I found the manual for the Low Noise Preamplifier Model 1201 at this link and I attached it.

The one we have in the lab (S/N 48332) miss the battery packs and miss also the remote programming options input/output. Its inside battery compartment is empty and I found 2 unscrewed screws with washers and nuts inside the preamplifier box. The battery cable are disconnected and they have 2 green tape labels (-) and 2 red tape label (+).

 

 

Attachment 1: ITHACO_1201_Instruction_&_Maintenance.pdf
ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf ITHACO_1201_Instruction_&_Maintenance.pdf
Attachment 2: DSC_3249.png
DSC_3249.png
  5033   Mon Jul 25 18:51:38 2011 ManuelUpdatePEMSTS-2 seismometer hardware testing with Jan

[Jan, Manuel, Jenne]

Jenne called Jan to check and figure out why the Streckeisen seismometer (SN #100151) doesn't work, hence we checked the output of the seismometer boxes as we did last friday. (This is the problem of seeing the X and Y channels saturated, when we look at them on a floating 'scope, as in the linked elog entry.)

Jan unplugged and plugged again the orange cable into the seismometer and nothing happened.   Well, what Jan was listening for was "clicks" inside the seismometer indicating that it was receiving power.  We heard these, and moved on to examining the breakout boxes.  Also, we checked that we could hear the "clicks" (one per mass) when we pushed the mass-centering button on the little green companion box.

We weren't sure that the purple box was working properly, so since we had seen the blue box work last time, we changed the purple box with the blue box in rack 1X6.

The Z-channel of the purple box returns a correct signal, that means that all the masses in the seismometer work (because the Z-signal is a linear combination of the three masses U, V, W), the X and Y channel have a DC component of about 10 Volts, Jan said that the recentering of the seismometer masses could need all the night, so we keep the power of the box on. If tomorrow morning the X and Y signal won't  both be zero mean, we will open and check the box.

The power of the box is still on so that the masses can recenter overnight.

Edits by JD

  5032   Mon Jul 25 17:16:02 2011 JamieUpdateSUSNow acquiring SUSXXX_IN1_DQ channels

> And.....we have also lost the DAQ channels that used to be associated with the _IN1 of the SUSPOS/PIT/YAW filter modules. Please put them back; our templates don't work without them.

I have (re?)added the SUS{POS,PIT,YAW,SIDE}_IN1_DQ channels.  I did this by modifying the activateDQ.py script to always turn them on [0].  They should now always be activated after the activateDQ script is run.

[0] This script now lives in the cds_user_apps repo at cds/c1/scripts/activateDQ.py

 

  5031   Mon Jul 25 13:09:39 2011 JamieUpdateCDSc1ioo Make problem

> It looks like something wrong with Makefile.

Sorry, this was my bad.  I was making a patch to the makefile to submit back upstream and I forgot to revert my changes.  I've reverted them now, so everything should be back to normal.

  5030   Mon Jul 25 13:01:24 2011 kiwamuUpdateCDSc1ioo Make problem

[Suresh / Kiwamu]

HELP US Jamieeeeeeee !! We are unable to compile c1ioo.

 

It looks like something wrong with Makefile.

We ran make c1ioo -- this was successful every time. However make install-c1ioo doesn't run.

The below is the error messages we got.

        make install-target-c1ioo
        make[1]: Entering directory `/opt/rtcds/caltech/c1/core/branches/branch-2.1'
        Please make c1ioo first

Then we looked at Makefile and tried to find what was wrong. Then found the sentence (in 36th line from the top) saying

        if test $(site)no = no; then echo Please make $$system first; exit 1; fi;\

We thought the lack of the site-name specification caused the error.

So then we tried the compile it again with the site name specified by typing

     export site=c1

in the terminal window.

It went ahead a little bit further, but it still doesn't run all through the Make commands.

 

  5029   Mon Jul 25 11:46:28 2011 steveUpdateSUSETMY sus problem hunt

[Kiwamu / Steve]

We checked some electronics noise on the ETMY shadow sensor system.

Noise from the WF, AA board and ADC are below the shadow sensor spectra on ETMY.

It means something funny is going on in the upstream side (including the satelight box and shadow sensors)

OR the coil drivers side are going crazy ??

 

As Rana pointed out in his entry (#5025), the spectra of the shadow sensors on ETMY were quite bad below 3 Hz. The floor are higher than that of ETMX by factor of 10 or so.

To check if the noise comes from some of the electronics, we disconnected D15-sub from pd to whitening in.

The spectra with/without shadow sensors are attached below.

The curves in brown and green are the ones taken when the shadow sensors were disconnected from the WF board.

So these two curves represent the summed noise of the WF, AA and ADC.

This tells us to look toward the OSEM.

 

Attachment 1: ETMY_AA_ADC.png
ETMY_AA_ADC.png
  5028   Mon Jul 25 11:06:38 2011 kiwamuSummaryGeneralWeekly report

Summary of the week ending July 24th.  Number of elog entries = 45


- LSC
 * Check of LSC WF switching
  -> some were switching, but the majority were not.

- SUS
 * Ran activateDQ.py for seeting some DQ channels of Oplevs
 * Turned ON all the offset buttons on the OL1, etc.
 * Rebuilt and restarted c1msc, c1sus, c1scx and c1scy as an update.
 * ETMY's shadow sensors look bad. Unknown noise below 3 Hz, which is higher than the usual floor by factor of 10.

- ABSL
 * The frequency lock was down.
 * The laser power into the RFPD had been too big, so it was reduced

- OAF
 * Seismometers were connected to the AA-board on 1X6
 * Most of the channels were acquired to the ADC, but some were not.

- Mode Cleaner
 * Gain of quadrants were checked.
 * Due to the SUS model update, the MC locking trigger hasn't worked correctly. This was fixed by changing ioo.db file

- Misc.
 * Virtual box was installed on Rossa. Altium is now available on Rossa.

  5027   Mon Jul 25 11:04:22 2011 kiwamuSummaryGeneralWeekly report

Summary of the week ending July 17th.  Number of elog entries = 20

- LSC
 * BO switching logic for the WF was installed on c1lsc
 * Channel mapping updated

- SUS
 * Oplev health check. Spectrum of each quadrant on every suspension was inspected and looked healthy.

- OAF
 * BNS interface board was attached to an AA board
 * The AA board was installed on 1X7. The Electro-optic fanout chassis on 1X7 is now sitting on a jack, this should be fixed.

- Fiber experiment (ALS)
 * Fibre from the ETMX and EMTY tables were routed to the PSL table

- Misc.
 * Alberto came over to the 40m with Wagonga
 
  5026   Mon Jul 25 11:02:19 2011 kiwamuSummaryGeneralWeekly report

 Summary of the week ending July 10th.  Number of elog entries = 21

- SUS

 + The cutoff frequency of the high pass filters for the damping were set to 30Hz.
 + Turned off all the BounceRoll filters.
 + The BS oplev was checked and seemed healthy.
 

- LSC


 + All the measred data of the LSC whitening filters were fit.
 + All the zpk parameters are recorded on the wiki.

- ABSL

 

+ The setup completed.  
 + The freqeucy-lock of the ABSL laser was achieved with UGF of ~ 40kHz.
 + The temperature of the ABSL laser was adjusted to be 47.25 deg
 

- ALS

 (Fiber experiment)
 + The I-P curve of the ETMY laser was measred.
 + The current set point is 1.8 [A], which used to be 1.5 [A], corresponding to the output of power of 197 [mW] and 390 [mW] respectively.
 

  5025   Mon Jul 25 00:35:44 2011 ranaUpdateSUSsomething wrong with ETMY LR sensor

a.png

Looks like either the LR OSEM is totally mis adjusted in its holder or the whitening eletronics are broken.

Also looks like the ETMY is just not damped at 1 Hz? How can this be?

I look at the SUS_SUMMARY screen which apparently only Steve and I look at:

bad.png

Looks like the suspensions have factor of 10-100 different gains. Why?

**  The ETMY just doesn't behave correctly when I bias it. Both pitch and yaw seem to make it do yaw. I leave this for Jamie to debug in the morning.

***  Also, the BIAS buttons are still broken - the HOPR/LOPR limits ought to be 5000 and the default slider increment be 100. Also the YAW button readback doesn't correctly show the state of the BIAS.

****  And.....we have also lost the DAQ channels that used to be associated with the _IN1 of the SUSPOS/PIT/YAW filter modules. Please put them back; our templates don't work without them.

  5024   Sun Jul 24 22:19:19 2011 haixingSummaryElectronicsAA filter tolerance analysis

 

>> This sort of OK, except the capacitor connects across the (+) terminals of the two input opamps, and does not connect to ground:

low_pass_new.png

 

>> Also, we don't care about the CMRR at 64 kHz. We care about it at up to 10 kHz, but not above.

In this case, the conner frequency for the low-pass filter would be around 100kHz in order to satisfy the requirement.


>>And doesn't the value depend on the resistors?

Yes, it does. The error in the resistor (typically 0.1%)  is much smaller than that of the capacitor (10%). Since the resistor error propagates in the same as the capacitor,
we can ignore it.

Note that we only specify the conner frequency (=1/RC) instead of R and C specifically from the tolerance analysis, we still need to choose appropriate
values for R and C with the conner frequency fixed to be around 100kHz, for which we need to consider the output impedance of port 1 and port 2.

 

 

  5023   Sun Jul 24 20:47:21 2011 ranaSummaryElectronicsAA filter tolerance analysis

This is sort of OK, except the capacitor connects across the (+) terminals of the two input opamps, and does not connect to ground.

Also, we don't care about the CMRR at 64 kHz. We care about it at up to 10 kHz, but not above. The sample frequency of the ADC is 64 kHz, but all of the models run at 16 kHz or less, so the Nyquist frequency is 8 kHz.

And doesn't the value depend on the resistors?

  5022   Sun Jul 24 20:36:03 2011 haixingSummaryElectronicsAA filter tolerance analysis

Koji and Haixing,

We did a tolerance analysis to specify the conner frequency for passive low-pass filtering in the AA filter of Cymac. The
link to the wiki page for the AA filter goes as follows (one can have a look at the simple schematics):
http://blue.ligo-wa.caltech.edu:8000/40m/Electronics/BNC_Whitening_AA

Basically, we want to add the following passive low-pass filter (boxed) before connecting to the instrumentation amplifier:

low_pass.png

Suppose (i) we have 10% error in the capacitor value and (ii) we want to have common-mode rejection
error to be smaller than 0.1% at low frequencies (up to the sampling frequency 64kHz), what would be
conner frequency, or equivalently the values for the capacitor and resistor, for the low-pass filter?

Given the transfer function for this low-pass filter:
transfer_function.png     f0.png
and the error propagation equation for its magnitude:
error.png
we found that the conner frequency needs to be around 640kHz in order to have
DT.pngwith Dc.png
 



  5021   Sat Jul 23 02:24:10 2011 SureshUpdateIOOrestarted the frame builder

I restarted the fb twice during the last 15mins.   This was after I added test points into the C1IOO/WFS1.mdl and C1IOO/WFS2.mdl.

  5020   Fri Jul 22 17:01:41 2011 Iron ManFrogsGeneralProof that Alberto lived through his Iron Man!

Alberto_IronMan_small.jpgIronman Vineman 70.3 logo

print 208 Alberto Stochino 67/129 585/1376 36:02 1:52 830 6:41 2:38:58 21.1 296 4:58 56:33 2:13:40 - 5:40:19
 
  5019   Fri Jul 22 15:39:55 2011 haixingUpdateSUSmatching the magnets

Yi Xie and Haixing,

We used the Gauss meter to measure the strength distribution of bought magnets, which follows a nice Gaussian distribution.
We pick out four pairs--four fixed magnets and four for the levitated plate that are matched in strength. The force difference is
anticipated to be within 0.2%, and we are going to measure the force as a function of distance to further confirm this.

In the coming week, we will measure various transfer functions in the path from the sensors to the coils (the actuator). The obtained
parameters will be put into our model to determine the control scheme. The model is currently written in mathematica which can
analyze the stability from open-loop transfer function.

  5018   Fri Jul 22 14:22:13 2011 Ishwita, ManuelUpdatePEMSTS-2 seismometer hardware testing

We have two STS-2 seismometer boxes... the blue box & the purple box. Initially we used the blue box for the STS-2 seismometer (named Bacardi by Jenne).

  • Oscilloscope powered on battery was used to test the blue box by observing the velocity output of the three axes (X, Y, Z).  It was found out that the mean value of DC volt of...

X = +10 V

Y = +11 V

Z = -0.1 V

Thus, X and Y axes showed abnormally high DC volt. It was also found out that in AC coupling mode of the oscilloscope... changes were observed in the signal received from Z axis when some seismic wave was generated near the Bacardi by jumping near it. No such changes were observed from signals received from X & Y axes.

  • We removed the blue box and used the purple box for the same Bacardi seismometer & used the oscilloscope powered on battery to test it. It was found out that the mean value of DC volt of...

X = +4.4 V

Y = +4.4 V

Z = +4.4 V

In Ac coupling mode of the oscilloscope... changes were observed in the signals from X, Y, Z axes when someone jumped near Bacardi.

  • The above voltages from the two STS-2 seismometer boxes are unsuitable for the ADC box since it works with voltages ranging from +2 V to -2 V.... meaning it will consider any voltage signal above +2 V as +2 V and any signal below -2 V as -2 V. Hence we need to find out how to use these STS-2seismometer boxes with the ADC box.
  • We also tried measuring the DC volt from the shield and the center of a BNC connector corresponding to Y axis of the purple box (lets call it 'BNC-test') by using BNC-to-banana adaptors and banana wires. Signal from shield of BNC-test was sent to oscilloscope's channel 1 (connected to center of its BNC connector) and signal from center of BNC-test was sent to oscilloscope's channel 2 (connected to center of its BNC connector). On the oscilloscope screen it was observed that both the signals gave the same mean voltage output (-2.2V).
  5017   Fri Jul 22 10:24:34 2011 steveUpdateVACpressure plot at day 213

Dec 21, 2010 we pumped down the MARK4 rebuilt 40m-IFO and the malev has been pumping on it since than

Attachment 1: p.jpg
p.jpg
  5016   Fri Jul 22 10:13:41 2011 steveUpdateVACRGA scan at day 213
Attachment 1: pd70m213scan.jpg
pd70m213scan.jpg
  5015   Thu Jul 21 23:36:51 2011 JennyUpdate Fitting beam waist with MATLAB

I am starting work on the PSL table at the 40m. My goal is to lock the laser coming from the nearby table to the FP cavity and get a measurement of the response to a temperature step on the surrounding can.

I have to mode match the beam to the cavity. Specifically, I have to mode match to the beam coming from the PMC through the EOM to the polarizing beam splitter. Yesterday David and I measured the beam width at various distances (from a particular lens through which the beam traveled), and I fit that data using MATLAB to find the beam's waist size and location. However, I'm not convinced that the fit is any good, since we only took measurements at five spots and they had large error bars.

 

z (mm) 2w_vert (mm) 2w_horiz (mm)
180 4.68 3.38
230 4.64 3.49
305 4.68 3.47
370 5.1 3.81
510 5.5 4.17

Here is the fit I obtained using fminsearch. The horizontal beam width measurements were smaller than the vertical width measurements, suggesting that the incoming beam was elliptical. I fit the data for each set of measurements separately and got two waist locations. The red trace is the fit for the horizontal width and the blue represents the vertical width of the beam. Averaging the two fitted waist locations and sizes gives

vert z_0= -1760 mm (waist location)

horiz z_0= -1540 mm (waist location)

vert w_0 = 0.286 mm (waist size)

horiz  w_0 = 0.275 mm (waist size)

avg z_0= -1650 mm

avg w_0 = 0.281 mm

 

twobeamfit2.jpg

Here is the code I used:

I defined the function spotsize.m and then made a function gaussbeam.m that called it with input parameters and returned the least squares error. I then wrote another function twobeamfits.m that ran fminsearch to minimize the least squares error and made the above plot. I've pasted the code below.

spotsize

function omega = spotsize(z_0, w_0, z)
lambda=0.001064;
omega=w_0*(1+(lambda*(z-z_0)/(pi*w_0^2)).^2).^(1/2);

 

gaussbeam

function sse = gaussbeam(params,xvals,yvals)

%This f'n takes as its inputs
%three parameters (w_0, z_0, and lambda),
%a vector of x-values (distances),
%and an associated vector of y-values (spotsizes),


%It then generates a vector of fitted y-values by applying
%an exponential approach function (single pole), with the given parameters,
%to the x-values.

%It then returns the sum of the squares of the entries of the difference
%between the fitted y-vector and the actual y-vector

z_0=params(1);
w_0=params(2);
fityvals=spotsize(z_0, w_0, xvals);

error=(fityvals - yvals);% .*xvals;
% sse stands for sum of squares error
sse=sum(error.^2);

 

twobeamfits

function [outputs] = twobeamfits(guesses, dists, vert, horiz)


%This f'n takes as its inputs
%two starting guess parameters (w_0 and z_0),
%a vector of distances (x-values),
%and two associated vectors of measured beam radii,

%the radius measured along the vertical axis

%and the radius measured along a horizontal axis (y-values).

%It then calls the gaussbeam f'n for each set of y-values and minimizes its output (sum of squares error)
%using the fminsearch f'n. It outputs the fit parameters it settles on.

%It then plots the input data, the fitted curves, and the residuals


fminopts=optimset('TolFun',1e-6,'MaxIter', 100000);
vertparams=fminsearch(@gaussbeam,guesses,fminopts,dists,vert);
fitvert=spotsize(vertparams(1), vertparams(2), dists);
resid1=(vert-fitvert)./vert;
spoterror=[.1, .1, .1, .1, .1]; %uncertainties, all in mm

fminopts=optimset('TolFun',1e-6,'MaxIter', 100000);
horizparams=fminsearch(@gaussbeam,guesses,fminopts,dists,horiz);
fithoriz=spotsize(horizparams(1), horizparams(2), dists);
resid2=(horiz-fithoriz)./horiz;


points=linspace(-2000,1000,1000);
figure(1)
hold off
clf
subplot(2,1,1)
hold on
errorbar(dists, vert, spoterror, 'x')
grid
errorbar(dists, horiz, spoterror, 'r*');
plot(points,spotsize(vertparams(1), vertparams(2), points));
plot(points,spotsize(horizparams(1), horizparams(2), points),'r');
xlabel('Distance z (mm)')
title('Gaussian Beam Fits')
ylabel('Spotsize w (mm)')
legend('Vertical Spotsize','Horizontal Spotsize','Vertical Fit',...
    'Horizontal Fit','Location','SouthEast')
hold off

subplot(2,1,2)
plot(dists,resid1,'x')
hold on
plot(dists,resid2,'r*');
xlabel('Distance (z)')
title('Residuals')
ylabel('Fractional Difference')
legend('Vertical Fit Residuals','Horizontal Fit Residuals',...
    'Location','SouthEast')
grid

outputs=[vertparams horizparams];

 

 

 

Later on I may repeat some measurements and try to gain more certainty in my fit. In the mean time I will use this beam profile for mode matching. 

 

  5014   Thu Jul 21 16:06:35 2011 steveUpdateSUSoplev gains today checked by conlog

 Present values agree with conlog records. It can be concluded that there were no big changes made. There are some 0.1-0.2 gain  and one polarity changes during the periods of Valera's visits.

 

  5013   Thu Jul 21 16:05:15 2011 sureshUpdateIOOPSL beam into MC realigned

 I realigned the PSL beam going into the MC.

The MC beam was realigned so as to maximise the power in the MC.  I minimised the MC_RFPD_DCMON dial on the MC_ALIGN screen while adjusting the two zig-zag mirrors at the end of the PSL table.

  5012   Thu Jul 21 12:19:29 2011 Jamie, KiwamuUpdateIOOMC Trans QPD working, now locking

It turns out that the MC_TRANS_SUM signal was being derived from the SUS-MC2_OL_SUM_INMON channel in the ioo.db file. 

However, this channel name was recently changed to SUS-MC2_OLSUM_INMON (no underscore between OL and SUM) when

I added the new OL_SUM epics channel to the sus_single_control library model (I forgot to mention it in my previous log on this change,

apologies).  This is why there appeared to be no signal.  This was also what was preventing the mode cleaner from locking, since

the MC_TRANS_SUM signal is used as a trigger in the MC autolocker script.

We modified the ioo.db file at /cvs/cds/caltech/target/c1iool0/ioo.db [0,1] to change the name of the channel that the

C1:IOO-MC_TRANS_SUM signal is derived from.  The diff on the ioo.db file is:

--- /cvs/cds/caltech/target/c1iool0/ioo.db	2011-07-21 11:43:44.000000000 -0700
+++ /cvs/cds/caltech/target/c1iool0/ioo.db.2011Jul21	2011-07-21 11:43:36.000000000 -0700
@@ -303,7 +303,7 @@
 {
         field(DESC,"MC2 Trans QPD Sum")
         field(PREC,"1")
-        field(INPA, "C1:SUS-MC2_OLSUM_INMON")
+        field(INPA, "C1:SUS-MC2_OL_SUM_INMON")
         field(SCAN, ".1 second")
         field(CALC, "A+0.001")
 }

We then rebooted the c1iool0 machine, and when it came back up the MC_TRANS_SUM channel was showing the correct values.

We then found that the MC autolocker was not running, presumably because it had crashed after the channel rename?

In any event, we logged in to op340m and restarted the autolockerMCmain40m script.

The mode cleaner is now locked.

[0] Rana's log where this was initially defined

[1] All of the slow channel stuff is still in the old /cvs/cds/caltech path.  This needs to be fixed.

 

  5011   Thu Jul 21 10:08:30 2011 steveUpdateSUSsus sensor summary

OSEM voltages to be corrected at upcoming vent: threshold ~ 0.7-1.2V, ( at 22 out of 50 )

ITMX_UL, UR, LL, LR, SD

ITMY_UL

ETMX_UL, UR, LL, LR, SD

ETMY_UL

SRM_UL, UR, LL

MC2_UR_SD

BS_UR, SD

MC3_UL, LR, LL

 

Attachment 1: sus_sensor.png
sus_sensor.png
  5010   Thu Jul 21 09:04:59 2011 valera, steveUpdateSUSoplev gains were not optimized

 

Hi Steve,

 
I did change the ETMY optical lever configuration: http://131.215.115.52:8080/40m/4795
And I left it in that state per Jamie's request.
 
I was going to work on the servo tuning but found that the whitening was not working at that time.
What I was going to do is to measure the open loop gain to make sure the servo is stable, then 
measure the noise and minimize the rms motion by tuning the gain and the filter transfer function.
 
I plan to come to the 40m lab on August 22 for two weeks.
 
Valera.
  5009   Wed Jul 20 23:31:44 2011 SureshUpdateIOOMC Trans QPD is down

 

The mode cleaner is not locking because the MC Trans QPD signal is not present.  There is light on the QPD when the MC flashes and its position has not shifted.  The cable is plugged in well into the sensor head.  The signal cable is labled "MC2 Opt Lever"  and it arrives on the 1X4 rack along with other Optical Lever cables. Pressing the connector in did not solve the problem.

 

  5008   Wed Jul 20 22:16:27 2011 Ishwita, ManuelUpdateElectronicslying seismometer cable and plugging it

We laid the cable along the cable keeper from the BACARDI seismometer to the rack 1X6, the excess cable has been coiled under the X arm.

We plugged the cable to the seismometer and to the seismometer electronics box in rack 1X6. We also plugged the AC power cable from the box to an outlet in rack 1X7 (because the 1X6 outlets are full)

With the help of a function generator we tested the following labeled channels of AA board...

2, 3, 11, 12, 14, 15, 16, 18, 19, 20 and 24

that are the channels that can be viewed by the dataviewer, also the channel 10 can be viewed but it's labeld BAD so we cannot use it.

We leveled the seismometer and unlocked it, and saw his X,Y,Z velocity signals with an oscilloscope.

  5007   Wed Jul 20 20:44:56 2011 JamieUpdateSUSAll sus models rebuilt and restarted

There were a couple of recent improvements to the sus_single_control model that had not been propagated to all of the suspension controllers.

Rebuilt and restarted c1mcs, c1sus, c1scx, and c1scy.  Everything seems to be working fine after restart.

  5006   Wed Jul 20 20:04:54 2011 JamieUpdateCDSC1:DAQ-FB0_C1XXX_STATUS sometimes unexplainably goes red

I have been noticing this happening occasionally, but I don't understand what is causing:

status-fb-red1.png

The channel in question above is C1:DAQ-FB0_C1SCX_STATUS.  This channel is (I believe) reporting some status of the front end model communication with the frame builder, but I'm not sure exactly what.

Usually this problem goes away when I restart the model or the frame builder, but it didn't work this time.  Tomorrow I will figure out what this channel means, why it's sporadically going red, and how to correct it.

  5005   Wed Jul 20 19:48:03 2011 JamieUpdateSUSRe: oplev gains today

 

 We have been modifying models that need to have their channels renamed to run activateDQ when Joe's post_build_script to is run. 

The trick is to integrate things to get the post_build_script running after every model build (getting it hooked in to the make file somehow).  We're working on it.

 I've added the following epics channels to sus_single_control model using the epicsOutput part:

  • OL_SUM
  • OL_PITCH
  • OL_YAW

These channels are now all available.  I'm not exactly sure how to ensure that they're being trended.  I'll check that tomorrow.

  5004   Wed Jul 20 19:24:12 2011 ranaUpdateSUSoplev gains today

I guess Valera forgot to elog it. Steve, please email him and get the info.

I started to check out the OL servos today so that our whole interferometer is not too floppy.

  • The ETMX OPLEV DAQ channels were not in the list. Jamie ran the activateDQ.py script and it came back. Right now, we have no diagnostics to know if people have run this or not so the frames will have missing data now and again depending on how forgetful the rebooters are. Perhaps we can get activateDQ put into the make file???
  • I turned ON all of the offset buttons on the OL1, etc. filter banks. This allows for the dark offsets to be set for the OL quadrants. With these buttons off it doesn't make any sense.
  • I noticed that there are white (INVALID) fields all over the OPTLEV_SERVO screens. This is just because the new SUS models have not captured all of the functionality of the old system. Needs fixing.

Untitled.png

Some of these OL spectra are not like the others...

 a.png

  5003   Wed Jul 20 18:44:54 2011 KojiSummarySUSWeekly Summary

Find Frank and ask him about those components.

  5002   Wed Jul 20 17:43:33 2011 sureshUpdateComputersrestarted the frame builder

I restarted the frame builder in the last 15mins. 

I was making a change to a DAC channel in the C1IOO model.

  5001   Wed Jul 20 14:42:34 2011 steveUpdateSUSoplev gains today

C1:SUS-ETMX_OLPIT_GAIN set to 1.0     OLYAW 1.0

                ETMY                                     -0.2                   -0.2

                ITMY                                        2.0                    -2.0

                ITMX                                        0.5                     0.5

                  BS                                          0.4                    -0.4

                PRM                                         0.5                    -0.7

                SRM                                         1.0                     1.0

Earlier today Rana and I made power spectra of ETMY_OPLEV_ERROR signals with servo on and off.

It was indicating that the servo is not doing anything. These gain values were not set since IFO rebuilt.

Valera's entries were searched also. He did not do such thing. Rana may know where it is in the elog if it happened.

  5000   Wed Jul 20 12:05:08 2011 NicoleSummarySUSWeekly Summary

Since last week Wednesday, I have since found a Pomona Electronics box (thanks to Jenne)

to use for my photosensor head circuit (to house the LED and 2 photodiodes). Suresh has

shown me how to use the 9-pin Dsub connector punch, and I have punched a hole in this box

to attach the Dsub connector. 

 

Since this past entry regarding my mechanical design for the photosensor head (Photosensor Head Lessons),

I have modified the design to use a Teflon sheet instead of a copper PCB and I have moved the LED

and photodiodes closer together, upon the suggestions of Jamie and Koji.  The distance between

components is now 0.112" instead of the initial 0.28".  Last night, I cut the PCB board for the LED

and photodiodes and I drilled holes onto the PCB board and Teflon sheet so that the two may be

mounted to the metal plate face of the Pomona box.  I still need to cut the viewer hole for and

drill screws into the face plate.

P7200054.JPG

I have also been attempting to debug my photosensor circuit (box and LED/photodiode combination).

Since this last entry (Painful Votlage Regulator and Circuit Lessons), Suresh has helped me to get the parts

that I need from the Downs Electronics lab (15 wire ribbon cable, two 9 pin D-sub connectors M,

one 15 pin D-sub connector M, one 16 pin IDC connector). Upon the suggestion of Jamie, I have

also made additional safety changes to the circuit by fixing some of the soldering connections

so that all connections are done with wires (I had a few immediate lines connected with solder).

I believe the the photosensor circuit box is finally ready for testing. I may just need some help

attaching the IDC connector to the ribbon cable. After this, I would like to resume SAFELY

testing my circuit.

 P7200055.JPG

I have also been exploring SimMechanics. Unfortunately, I haven't been able to run the

inverted pendulum model by Sekiguchi Takanori. Everytime I attempt to run it, it says

there is an error and it shuts down Matlab. In the meanwhile, I have been watching

SimMechanics demos and trying to understand how to build a model. I'm thinking that

maybe once I figure out how SimMechanics works, I can use the image of his model

(I can see the model but it will not run) to construct a similar one that will hopefully work.

 

I have also been attempting to figure out the circuitry for the pre-assembled

accelerometer (made with the LIS3106AL chip).  I have been trying to use a multi-meter

to figure out what the components are (beyond the accelerometer chip, which I have

printed out the datasheet for), but have been unsuccessful at that. I have figured out

that the small 5 pin chip says LAMR and is a voltage regulator. I am hoping that if I can

find the data sheet for this voltage regulator, I can figure out the circuitry. Unfortunately,

I cannot find any datasheets for a LAMR voltage regulator. There is one by LAMAR, but

the ones I have seen are all much larger. Does anyone know what the miniature voltage

regulator below is called and if "LAMR" is short for "LAMAR"?

 

P7200056.JPG

 

  4999   Wed Jul 20 11:42:47 2011 Ishwita, ManuelUpdate Weekly summary
  • We gave a white-board presentation on derivation of formula for optimum Wiener filter coefficients and wrote a latex document for the same. relevant elog entry
  • We enjoyed drilling the cover of the AA board and fixing it.
  • The AA board was fixed on rack 1X7 with Jenne's help. relevant elog entry
  • We tried writing a simulation for the transfer function of the stacks in Matlab. Once we get some satisfying results, we will post it on the elog.
  • We started reading the book 'Digital Signal Processing - Alan V. Oppenheim / Ronald W. Schafer' and are still reading it. We also tried watching lecture videos on z-transform...
  4998   Wed Jul 20 11:13:59 2011 Larisa ThorneUpdateelogI restarted the ELOG as it seemed to have crashed

 

  4997   Wed Jul 20 10:10:19 2011 SonaliUpdateGreen LockingWeekly summary

 I finished wih the set-up at the ETMY table. Instead of the neutral Density Filter , I put in a mirror(Y1-1037-45S)  which is reflective for IR , so that only 1% of the light is incident on the fibre  as per Rana's suggestion.

Now, the power incident on the fibre is measured to be 6 mW and the power measured out of the fibre is 2.76 mW after the necessary alignments.

On the PSL able, I have routed the beam that is coming out of the back of the PMC(instead of the dumped light from the oven to prevent any light from reflecting back into the laser), to the area where I am putting the set-up for the superposition of the PSL and the ETMX and ETMY beams.

Today I will proceed with the layout.

ELOG V3.1.3-