||Tue Jun 28 07:46:54 2011
||Suresh||Update||IOO||Power incident on REFL11 and REFL55|
I measured the power incident on REFL11 and REFL55. Steve was concerned that it is too high. If we consider this elog the incident power levels were REFL11: 30 mW and REFL55: 87 mW. (assuming efficiency of ~ 0.8 A/W @1064nm for the C30642 PD). However, currently there is a combination of Polarising BS and Half-waveplate with which we have attenuated the power incident on the REFL PDs. We now have (with the PRM misaligned):
REFL11: Power incident = 7.60 mW ; DC out = 0.330 V => efficiency = 0.87 A/W
REFL55: Power incident = 23 mW ; DC out = 0.850 V => efficiency = 0.74 A/W
and with the PRM aligned::
REFL11: DC out = 0.35 V => 8 mW is incident
REFL55: DC out = 0.975 V => 26 mW is incident
These power levels may go up further when everything is working well.
The max rated photo-current is 100mA => max power 125mW @0.8 A/W.
||Tue Jun 28 02:11:47 2011
||Jenne||Update||Locking||Latest MICH noise budget|
I have measured / calculated the latest MICH noise budget. It doesn't really look all that stellar.
As you can see, we are nowhere near being shot noise limited, since there's a huge discrepancy between all of the measured spectra and the teal Shot Noise line.
One possible suspect is that the analog whitening filters weren't on when I took my measurements. I didn't actually check to ensure that they were on, so they might not have been. Right now we're limited by electronics and other boring noises, so I need to make sure we're limited by the noise of the diode itself (we don't have enough light in the IFO to actually be shot noise limited since that takes 2.5mA for AS55 and I only have 1.1mA, but we should be ~within a factor of 2ish).
||Tue Jun 28 01:18:53 2011
||rana||HowTo||SUS||free swing all optics|
Chris Wipf tells me that the EPICS Mutex Jumbo Mumbo can be overcome by upgrading our EPICS. We should get one of Jamie's assistants to get this going on one of the Ubuntu workstations.
||Mon Jun 27 16:57:06 2011
||steve||Update||Photos||Haixing is back|
He has moved the levitation stuff for his surf student to Jan's lab in W-Bridge.
||Mon Jun 27 10:04:29 2011
Summary for the week ending June 26th. (Number of elog entries = 53)
A BIO installed on 1X2.
A peak finding script was prepared for diagonalization of the OSEM input matrices
The suspension readout coefficients were changed to have unit of [um] and [urad] in each signal.
LWE NPRO controller was brought by Peter King.
The I-P cuvre and beam profile was measured. Nominal current was chosen to 1.8 [A].
The access tube between PSL and AS table was back in place.
The REFL55 characterization was analyzed (impedance gain = 615 Ohm, shot noise intercept current = 1.59 mA )
WFS1 check, the 29MHz resonance need to be adjusted.
The MC locking gain was increased by 6 dB to avoid an oscillation at 30 kHz.
The sensing matrices were measured in DRMI configuration and PRMI configuration
- Fiber experiment
QPDY_PD was repositioned to accommodate the fiber stuff on the ETMY table.
Succeeded in introducing the IR beam into the fiber coupler.
- TT characterization
Th optic bench next to MC2 was cleaned up and leveled
- Vent list wiki page
A wiki page was made for the vent detailed plan.
A foton's malfunction was found. It can run correctly only on Pianosa.
Some Dell machines were gone to Rod Luna
- 40m specfic safety training for the SURFs
||Mon Jun 27 00:23:11 2011
||rana||Update||CDS||ETMX SIDE problem|
The slow readback of the ETMX side seems to also have something flaky and bi-stable. This is not an issue for damping, but it disables the SIDE watchdog for ETMX and makes it unsafe if we accidentally use the wrong damping sign.
||Sun Jun 26 22:38:20 2011
||rana||Update||CDS||MC1 LR dead for > 1 month; now revived temporarily|
Since the MC1 LRSEN channel
is not wasn't working, my input matrix diagonalization hasn't worked today wasn't working. So I decided to fix it somehow.
I went to the rack and traced the signal: first at the LEMO monitor on the whitening card, secondly at the 4-pin LEMO cable which goes into the AA chassis.
The signal existed at the input to the AA chassis but not in the screen. So I pressed the jumper wire (used to be AA filter) down for the channel corresponding to the MC1 LRSEN channel.
It now has come back and looks like the other sensors. As you can see from this plot and Joe's entry from a couple weeks ago, this channel has been dead since May 17th.
The ELOG reveals that Kiwamu caught Steve doing some (un-elogged) fooling around there. Burnt Toast -> Steve.
993190663 = free swinging ringdown restarted again
||Sun Jun 26 18:35:16 2011
||rana||HowTo||SUS||free swing all optics|
I used scripts/SUS/freeswing-all.csh to give the optics a kick and then turn off their watchdogs and collect the free swinging data. Final script end time = 993173551. Start taking data ~ 993173751
I had to fix up the script a little: it had amateur stuff in there, such as undefined variables.
It still doesn't work that well. On the new Ubuntu workstations, pianosa, it fails by just not setting some of the EPICS variables using the EZCA stuff.
On Allegra, it failed on ~1 out of 10 commands by returning "epicsThreadOnce0sd epicsMutexLock failed" ???
On Pianosa, it sometimes says, instead, "
epicsThreadOnceOsd: pthread_mutex_lock returned Invalid argument.". Ah...now I understand?
So finally, I had to run the script on op340m to get it to actually run all of its commands. That's right; I used a 15 year old Solaris 9 Blade 150 because none of our fancy new Linux machines could do the job reliably.
Fixing our EZCA situation is a pretty high priority; if the locking scripts fail to run ~1 command every hour its going to completely derail the lock acquisition attempts.
If you want to use the IFO tonight, just run the script again on op340m again when you're done.
||Sun Jun 26 16:17:22 2011
||rana||Update||CDS||diagonalization of MC input matrix|
I have updated the scripts/SUS/peakFit/ directory so that it now finds the SUS input matrix coefficients in addition to just finding the free-swinging peaks.
- Get OSEM sensors data via NDS2 from a time when the optics have been kicked and then left free swinging.
- Downsample the data to 64 Hz and save.
- Make power spectra with a 1 mHz resolution (i.e. we need a few hours of data) and ~10 averages.
- use the fminsearch lorentzian peak fitter -> save the peak frequencies
- Make Transfer Function estimate matrix at the peak frequencies between all OSEMs (this makes a 5x4 complex matrix)
- The matrix should be real, so make sure its mostly real and then take the real part only
- Normalize (height of biggest peak for each f_DOF should be 1)
- Add a Butterfly mode vector. This makes the sensing matrix go from 5x4 to 5x5. (Butterfly a.k.a. Pringle)
- Normalize so that the biggest element in each Sensor2DOF column is 1.
- Load values into MEDM screen and then verify by another free swinging data run.
The attached PDF shows how much rejection of the unwanted DOFs we get between the existing diagonal input matrix and this new empirical matrix. Previously, the decoupling was only a factor of a few for some of the modes. Now the decoupling is more like orders of magnitude (at least according to this calculation). It will be worse when we load it and then try another free swinging run. However, the fact that the suppression can be this good means that the variation in the coefficients at the ~hours time scale is at least this small (~< 0.1%)
That's the basic procedure, but there are a lot of important but mainly technical details:
- Free swinging data must be taken with the angle bias ON. Otherwise, we are not measuring the correct sensing gain (i.e. the magnets are not in their nominal place within the OSEM-LED beam)
- Data must be checked so that the shadow sensor outputs are in their linear regime: if they are exploring the cubic part, then the fundamental is being suppressed.
- Instead of just using the peak frequency, I average a few points around the peak to get better SNR before inversion. I think this will make the results more stable.
- All previous input matrix diagonalization efforts (Buckley, Sakata & Kawamura, Black, Barton, Gonzalez, Adhikari & Lawrence, Saulson,...) for the past ~15 years have been using the spectra's peak height data. Today's technique uses the TF and so is more precise. The coherent transfer function is always better than just using the magnitude data.
- This method is now fairly automatic - there's no human intervention in fudging values, choosing peak heights, frequencies, etc.
- We'll have to rerun this, of course, after the mirrors are aligned and after the OSEM whitening fiasco is cleaned up somewhat.
I'll set the optics to be aligned and then swing tonight.
||Sun Jun 26 16:02:12 2011
||kiwamu||Update||IOO||Friday MC activity|
[Rana / Kiwamu]
Last Friday we did several things for MC :
- aligned the incident beam to MC
- increased the locking gain by 6 dB and modified the auto-locker script accordingly
- improved the alignment of the beam on the MC_REFLPD photo diode
In the beginning of the work, we wanted to know what RF frequency components are prominent in the reflection from MC.
Since the WFS circuits are capable for two RF notches, we wanted to determine which frequencies are appropriate for those notches.
So for the purpose we tried searching for unwanted RF components in the reflection.
However during the work, we found several things that needed to be fixed, so we spent most of the time for improving the MC locking.
- Alignments of the incident beam
At the beginning, the reflection from MC was about 2.2 in C1:IOO-REFLDC and the lock of MC had been frequently unlocked.
This situation of high reflection seemed to be related to a work done by Suresh (#4880).
Rana went to the PSL table and tweaked two input steering mirrors in the zig-zag path, and finally the reflection went down to ~ 0.8 in C1:IOO-REFLDC.
This work made the lock more robust.
- Change of the locking gain
After the alignment of the incident beam, we started looking at the time series of the MC_REFLPD signal with an oscilloscope as a start point.
What we found was a significant amount of 30 kHz components. This 30 kHz oscillation was thought be a loop oscillation, and indeed it was so.
We increased the loop gain by 6 dB and then the 30 kHz components disappeared successfully.
So the nominal locking gain of MC is now 11 dB in C1:IOO-MC_REFL_GAIN. The auto locker script was also modified accordingly.
- RF components in the MCREFL signal
After those improvements mentioned above, we started looking at the spectrum of the MCREFL PD using the spectrum analyzer HP8590.
The 29.5 MHz component was the biggest components in the spectrum. Ideally this 29.5 MHz signal should be zero when MC is locked.
One possible reason for this big 29.5 MHz signal was because the lock point was off from the resonant point.
We tweaked the offset in the MC lock path using a digital offset, C1:IOO-MC-REFL_OFFSET.
We found an offset point where the 29.5MHz signal went to the minimum, but didn't go to zero.
(works to be done)
So it needs some more works to investigate the cause of nonzero 29.5 MHz signal as well as investigation of what RF components should be notched out.
A good start point would be writing a GPIB interface script such that we can get the spectra from HP8590 without any pains.
||Sat Jun 25 06:09:38 2011
I was able to measure the sensing matrix in the PRMI configuration.
The results will be posted later.
||Sat Jun 25 04:40:43 2011
||Suresh||Update||ASC||WFS1 Transimpedance measurement|
The attached plots show the location of the ~29.5 MHz pole and the 59 MHz notch for each quadrant of the WFS1 Sensor head.
As may be seen from the above table, these frequencies will need to be adjusted in some cases.
From the plots we can see that, when there is no attenuation set on the attenuator AT65-0263 (ref D990249-A), the MAX4107 oscillations are seen in Q2,Q3,Q4 quadrants at around 200 MHz.
Rana suggested, from his previous encounter with this circuit, that the solution is to remove the second MAX4106 and the attenuator on the RF line to avoid this oscillation.
A look at the circuit board shows that some of the inductors have not been mounted. That explains the presence of only one notch though the schematic shows two.
||Sat Jun 25 00:00:28 2011
||Sonali||Update||Green Locking||Fibre Coupling.|
What I did today.
1. I tried to align the IR input beam by aligning the two mirrors, to couple input light into the fibre.
2.I was unsuccessful for a long time even though I tried a lot of tricks.
3. I also tried to use the optical fault locator to superpose the IR beam spot onto the beam spot of the other laser to facilitate effective coupling.
4.But the crucial point was to superpose the input beam path in the perfect direction of the output beam path and not just the beam spot.(the input cone and the output cone are perfectly aligned).
5.After one whole day of trial and thought, I managed to couple light into the fibre, and saw the output beam spot on the screen-camera-monitor set-up which we had arranged. Eurekka !!;)
6.I then used a power meter to measure the input beam power and the output beam power.
7.It was a disappointing 2% . I had read in project reports of many students of a 20% success.
8.After a lot of subtle tweaking of the mirrors using the knobs, I managed to increase the percentage of output beam to 12%.
9. This is a workable level.
10.A day of lot of new learning! Pictures of the setup are attached.:)
||Fri Jun 24 22:35:23 2011
||rana||Configuration||CDS||dataviewer broken on pianosa|
When I try to get minute trend, it says "word too long".
||Fri Jun 24 21:21:46 2011
||Suresh||Update||PSL||Placed labels on the zig-zag mirrors on PSL table|
I put labels on the pair of beam steering mirrors which are at the output end of the PSL table. I had changed one of these mirrors (elog) and Jenne had changed the other (elog). This was at about 3PM today
I just learned from Kiwamu that this has messed up the MC alignment.
||Fri Jun 24 17:04:25 2011
||Nicole||Update||SUS||Basic Laser Safety Training; Moved TT Mirror; Horizontal Displacement Mech Plan|
Today Ishwita, Sonali, and I completed basic laser safety training with Peter King. I completed the Laser Safety Quiz and have turned in my certificate sheet.
I just need to turn in a signed copy of the Lab Safety Checklist to SFP (which I can now have signed by Koji after completing the course).
Steve and I have removed the TT mirror from the clean box. It is now on the small optical table in the lab that I have been working on. Thanks to Steve, all of the mechanical components for the horizontal displacement measurement experiment are compiled and on the small optical table. Here is a photo of the small optical table with the gathered components.
The plan is to attach the slider and the shaker directly to the black mounting plate. On the slider, we we then place the smaller black mounting plate (with the lip). The lip will attach to the shaker. We know exactly where to drill and everything is lined up. The shaker will be placed on the smaller black mounting plate (with the lip). The assembly will begin on Monday.
Here is a photo of the planned set-up for the shaker and the horizontal slider + mounting base.
||Fri Jun 24 10:38:01 2011
||steve||Update||Cameras||ITMY camera gets fixed|
ITMY gets new Tamron M118FM50 that has improved close focusing. It is a small fixed focal length camera so the video tube cover can be put on.
The Watec LCL-902K 1/2" ccd camera was losing it power supply voltage because of bad connection. It was replaced.
||Fri Jun 24 07:49:23 2011
||steve||Update||ABSL||I-P curve of LWE with serial numbers|
The I-P curve was measured again, but this time in a lower current range of 1.0-1.9 [A].
|Quote from #4842
The old days the NPRO ( inside the MOPA ) was running ~1.7A 500 mW
Lightwave Laser Head M126-1064-700 sn238, mounted on full size Al base and side heat sink on
Controller 125/126 Smart Supply sn 201M
||Fri Jun 24 07:40:23 2011
||steve||Update||SUS||PRM damping restored|
The PRM sus damping restored. C1:SUS-PRM_SDPD_VAR is still 20-30mV and going up. Side gain turned on. This pulled it down to 5-8 mV
Why is the side osem sensing voltage 4.4V ? It can not be higher than ~2.4V.......something is rotten in the state of Denmark?
Edit by KI:
It's because Valera increased the transimpedance gain of the PRM SIDE OSEM to match the signal level to the new ADC range (#3913 ).
||Fri Jun 24 01:05:32 2011
||Nicole||Summary||SUS||Transfer Function Model Analysis Summary and New Posted LED V vs. I Curve|
I have updated the TT suspension wiki to include a new page on my transfer function model. In this new page, an introduction and analysis of my transfer function (including a comparison of the transfer functions for a flexibly- and rigidly-supported damper) are included. This page contains linear and logarithmic bode plots. Here is a link to the transfer function page.
I have also updated my photosensor page on the TT suspension wiki so that the experimental data points in my current versus voltage plot are plotted against the curve provided by the Hamamtsu data sheet. I have also included an introduction and analysis for my mini-experiment with the forward voltage and forward current of the LED. Here is link to the photsosensor page.
||Fri Jun 24 00:13:24 2011
||kiwamu||Update||ABSL||beam profile measurement of LWE|
The beam profile of the LWE (LightWave Electronics) NPRO was measured.
Mode matching telescopes will be designed and setup soon based on the result of the measurements.
Here is a plot of the measured beam profile.
The measurement was done by using Kevin's power attenuation technique (#3030).
An window was put just after the NPRO and the reflected beam was sampled for the measurement to avoid the beam scan saturated.
||Thu Jun 23 23:54:29 2011
||Koji||Omnistructure||Environment||We are saved|
Sonali, Ishwita, and another anonymous SURF saved the long-lasted water shortage of the 40m
||Thu Jun 23 22:59:45 2011
||kiwamu||Update||ABSL||I-P curve of LWE|
The I-P curve was measured again, but this time in a lower current range of 1.0-1.9 [A].
The plot below is the latest I-P curve.
Based on the measurement and some thoughts, I decided to run this laser at about 1.8 [A] which gives us a middle power of ~ 360 [mW].
In the 40m history, the laser had been driven at 2.4 [A] in years of approximately 2006-2009, so it's possible to run it at such a high power,
but on the other hand Steve suggested to run it with a smaller power such that the laser power doesn't degrade so fast.
The laser controller handed from PK (#4855) was used in this measurement.
The nominal current was tuned to be 1.8 [A] by tuning a potentiometer on the laser head (see page.18 on the manual of LWE).
There was a huge bump around 1.4 [A] and sudden power drop at 1.48 [A] although I don't know the reason.
|Quote from #4842
The old days the NPRO ( inside the MOPA ) was running ~1.7A 500 mW
||Thu Jun 23 22:53:02 2011
I found some DQ channels (e.g. SENSOE_UL and etc.) for C1SUS haven't been activated, so I ran activateDQ.py.
Then I restarted daqd on fb as usual. So far the DQ channels look working fine.
||Thu Jun 23 22:39:34 2011
||Jenne||Update||PSL||PMC found unlocked|
I found the PMC unlocked. Koji noticed that the FSS Slow Actuator Adjust was railed at the positive end of the slider. I set it close to zero, and relocked the PMC. The FSS slow loop servo is doing its thing, and the PMC and MC are now locked.
||Thu Jun 23 22:00:22 2011
I recorded a burt snapshot of these settings: /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2011/Jun/23/21:40
||Thu Jun 23 21:35:46 2011
||Jamie, Rana, Kiwamu||Update||SUS||Fix calibration for sus sensors|
We have fixed the counts-to-micron (cts2um) calibration for the suspension sensor filters. Each suspension sensor filter bank (e.g. ULSEN) has a "cts2um" calibration filter. These have now been set with the following flat gains:
40 V 10^3 um um
-------- * -------- = .36 --
2^16 cts 1.7 V ct
The INMTRX was also fixed with proper element values:
This was done for all core optic suspensions (BS, PRM, SRM, ITMX, ITMY, ETMX, ETMY).
||Thu Jun 23 21:34:21 2011
||kiwamu||Update||CDS||no foton on the CentOS machines |
For some reasons foton's deafault sample rate is NOT correct when it runs on the CentOS machines.
It tries to setup the sample rate to be 2048 Hz instead of 16384 Hz until you specify the frequency.
To avoid an accidental change of the sample rate,
running foton on CentOS is forbidden until any further notifications.
Run foton only on Pianosa.
Additionally I added an alias sentence in cshrc.40m such that people can not run foron on CentOS (csh and tcsh, technically speaking).
Below is an example of raw output when I typed foron on a CentOs machine.
DO NOT use foton on CentOS
||Thu Jun 23 10:35:12 2011
||steve||Update||Computers||old computers leaving the lab|
Rod Luna picked up these computers for Larry Wallace yesterday: Dell Inspiron 530, Dell Dimension 4600 and SunBlade 1000
||Thu Jun 23 10:17:49 2011
||steve||Update||PSL||AP table is open to PSL again|
Access to the north side of the PSL table is blocked by the 8" beam guard. This opens the beam pathways between them.
||Thu Jun 23 09:46:16 2011
||rana||Update||LSC||PRMI locking : not stable enough|
All the suspensions are bad until you fix them. But, ... there is a script which can be used to diagnose them today:
||Thu Jun 23 05:22:51 2011
||kiwamu||Update||LSC||PRMI locking : not stable enough|
I was trying to measure the sensing matrix in the PRMI configuration, but basically gave up.
It is mainly because the lock of PRMI wasn't so stable and it didn't stay locked for more than a minute.
It looked like an angular motion fluctuated a lot around 1- 3 Hz. The beam spot on the AS camera moved a lot during the lock.
I have to figure out who is the bad suspension and why.
||Thu Jun 23 02:12:12 2011
||Sonali||Update||Green Locking||work schedule.|
June 22-June 24:
1.Coupling light into fibre at the ETMY.
2.Routing of the fibre to the PSL table.
June 27-June 30:
1.PSL optical table layout sketching.
2.Combining the PSL beam with fibre output onto a BS and then superpose them on a New Focus 1611 PD.
July 5-July 8:
1.Conversion of the PD output to voltage using MFD(Mixer Frequency Discriminator).
2. Report writing.
July 7: 5:00 pm: 1st Report Due.
July 11-July 22:
1.Locking Y-arm to PSL.
2.Setting up the feedback loop using the MFD output as the error signal and acting on the AUX laser frequency.
July 25-Aug 5:
1.Y-Arm cavity characterisation.
Measurement of the transmission of IR and green light through the cavity.
To obtain FSR, Finesse,Loss of the Cavity, Visibility, Transverse Modes(g-factor, astigmatism), Reflectivity, Q-factor.
3.Report and abstract writing.
Aug 1: 5:00 pm: 2nd Report and absract due.
Preparation for talk and seminar.
||Wed Jun 22 21:36:41 2011
||rana||Summary||General||July 2011 vent plan|
I put a paper Peet's bag with half of the Mini-Moos into George.
||Wed Jun 22 18:51:47 2011
||Suresh||Update||IOO||WFS2 RF response|
I have shifted the Jenne laser back to the small table where we do RF PD characterisation (RFPD table). I found several 25pin D-type connector cables, connected them in tandem and am using that to power the WFS2 sensor head at the RFPD table.
The set up is ready for looking at the RF response of the WFS sensors. Will continue tonight.
||Wed Jun 22 18:50:45 2011
||Jamie||Summary||General||July 2011 vent plan|
Kiwamu and I have started to put together a vent plan on the 40m wiki:
We will keep working on this (there's still a *lot* to fill in), but please help fill in the plan by adding questions, answers, procedures, preparations, etc.
||Wed Jun 22 18:41:23 2011
||Nicole||Summary||SUS||BROKEN bread board circuit box and L9337 LED Current Versus Voltage Curve|
NOTE: The potentiometers on the bread board circuit box (the one I have been using with the signal generator, DC power, LED displays, and pulse switches) is BROKEN!
The potential across terminals 1 and 2 (also 2&3) fluctuates wildly and there dial does not affect the potential for the second potentiometer (the one with terminals 4, 5, and 6).
This has been confirmed by Koji and Jaimie. PS I didn't break it! >____<
NEVERTHELESS, using individual resistors and the 500 ohm trim resistor, I have managed to get the current versus forward voltage plot for the Hamamatsu L9337 Infared LED
||Wed Jun 22 17:42:03 2011
||kiwamu||Update||LSC||sensing matrix measurement|
The sensing matrix was measured in the DRMI configuration for the first time.
The measurement was done by an automatic script and the realtime LOCKIN module built in the c1lsc model.
The resultant matrix is still too primitive, so I will do some further analysis.
(Measurement of sensing matrix)
The quantities we want to measure are the transfer functions (TFs) from displacement (or change in optical phase) of each DOF to sensors in unit of [counts/m].
So essentially the measurement I did is the same as the usual TF measurement. The difference is that this measurement only takes TFs at a certain frequency, in this case 283 Hz.
The measurement goes in the following order :
(1) Lock DRMI
(2) Shake an optic of interest longitudinally with an amplitude of 1000 counts at 283.103 Hz, where no prominent noise structures are present in any spectra of the sensor signals.
(3) Put a notch filter at the same frequency of 283.103 Hz in each DOF (MICH, PRC and SRC) to avoid unwanted suppression due to the control loops.
(This technique is essentially the same as this one, but this time the control loops are shut off only at a specific frequency )
The notch filter I put has a depth of 60 dB and Q of 20. The filter eats the phase of ~10 deg at 200 Hz, which still allow servos to run with a high UGF up to 200Hz.
(4) Take the output signal from a signal port of interest (i.e. REFL11_I, etc.,) and then put it into the realtime LOCKIN module.
(5) Measure the resultant I and Q signals coming out from the LOCKIN module.
(6) Repeat the procedure from (2) through (5) for each optic and sensor.
Again, the resultant sensing matrix is still primitive, for example the optic-basis should be converted into the DOF basis.
The values listed in the matrix below is the absolute values obtained by operation of sqrt( I^2 + Q^2) plus the polarity according to the output from I and Q of LOCKIN.
Therefore they still contain the actuator response, which is not desired. i will calibrate them into [counts/m] later by using the calibration factor of the actuator responses.
All the raw data showed the relative phase between I and Q either ~ 127 deg or ~ -53 deg.
In my definition, the one has 127 deg is plus polarity and the one has -53 deg is minus polarity.
Technically speaking the polarity depends on the polarity of the actuator and also the direction of the actuator against the DOFs.
Without any excitation the absolute values fluctuated at about 10-4 - 10-5, so the excitation amplitude was big enough to observe the sensing matrix.
Though, I still need to estimate the statistical errors to make sure the SNR is reasonably big.
Fig.1 Measured sensing matrix from optic to sensors.
(Things to be done)
- convert the optic-basis (i.e. BS, ITMs, PRM and SRM) to the DOF-basis (i.e. MICH, PRC and SRC) so that the matrix is understandable from point of view of the interferometer control.
- estimate the optimum demodulation phase for each DOF at each sensor port.
- add some statistical flavors (e.g. error estimations and so on.)
- edit the script such that it will keep watching the ADC overflows and the coherence to make sure the measurement goes well.
- add some more signal ports (e.g. REFL55, POY55 and etc.)
- compare with an Optickle model
|Quote from #4851
The result will be updated later.
||Wed Jun 22 17:35:35 2011
||Ishwita||Update||General||Hot air station|
This is the new hot air station for the 40m lab.........
||Wed Jun 22 15:24:10 2011
||kiwamu||Update||ABSL||got a laser controller for LightWave|
Peter King came over to the 40m with a laser controller and gave it to us.
We will test it out with the LightWave NPRO, which was used for MOPA.
||Wed Jun 22 12:29:57 2011
||Ishwita||Summary||Adaptive Filtering||Weekly summary|
I started on the 16th with a very intense lab tour & was fed with a large amount of data (I can't guarantee that I remember everything....)
Then... did some (not much) reading on filters since I'm dealing with seismic noise cancellation this summer with Jenne at the 40m lab.
I'll be using the Streckeisen STS-2 seismometers & I need to use the anti aliasing filter board that has the 4 pin lemo connectors with the seismometers & its boxes that require BNC connectors. I spent most of the time trying to solder the wires properly into the connectors. I was very slow in this as this is the first time I'm soldering anything.... & till now I've soldered 59 wires in the BNC connectors....
||Wed Jun 22 12:24:44 2011
||Nicole||Summary||SUS||Midweek 2 Work Summary|
I have made my transfer function model and posted it to the suspension wiki. Here is the link to my model!
Bode Plot Model
Please let me know if there need to be any adjustments, but I have posted the bode plots, a model image, and an explanation of why I think it's right! ^ ___^ V
I am currently working on the photo sensor circuit for the displacement detector. So far, I have gotten the infared LED to light up! ^ ___^ V
I am now trying to get a plot of forward voltage versus current for the LED. HOPEFULLY it will match the curve provided in the LED datasheet.
I'm using the bread board circuit box and when I'm not working at the bench, I have signs posted. PLEASE DO NOT REMOVE THE CONNECTIONS! It is
fine to move the bread board circuit box, but please do not disturb the connections > ____<
Here is a photo of the workspace
||Wed Jun 22 01:59:43 2011
||Sonali||Update||Green Locking||fibre-coupling of the IR beam |
What I did today.
1. Collimation of a beam.
- I then practiced collimation of a 700 nm laser (output) beam after being coupled through a fibre.
- I put together the set-up as shown in the attached picture where I used ....... to couple 650nm light into the PM.... fiber.
- I kept shifting the focus of the output beam to an appreciable distance till it was approximately collimated.
2. Coupling of the IR light at the ETMY table to a fibre.
- The fibre coupler was put in place to couple light into the fiber.
- I put in the mirrors as planned to direct the IR beam exiting the doubling crystal towards the fiber coupler (input).
- The mirrors were aligned such that the beam falls on the input lens of the coupler.
- The far-end of the fibre originally would have gone to to PSL table but it has been put on this table to study the power of the IR beam transmitted through this set-up. The output end of the fiber has been connected to another fiber optic coupler to collimate the exiting beam.
- The picture of the current status attached.
||Tue Jun 21 23:29:41 2011
||kiwamu||Update||LSC||sensing matrix measurement|
I am now measuring the sensing matrix in the DRMI configuration.
A goal of tonight is to measure the sensing matrix as a test of the script.
The result will be updated later.
||Tue Jun 21 20:35:50 2011
||kiwamu||Update||LSC||a script to measure sensing matrix|
Last night I was making a script which will measure the sensing matrix using the realtime LOCKIN module.
The script is a kind of expansion of Jamie's one, which measure the asymmetry, to more generic purpose.
It will shake a suspended optic of interest and measure the response of each sensor by observing the demodulated I and Q signals from the LOCKIN module.
I will continue working on this.
- made a function that drives the LOCKIN oscillator and get the data from the I and Q outputs.
- checked the function with the MICH configuration.
ITMX, ITMY and BS were shaken at 100 Hz and at different time.
Then the response of AS55_Q showed agreement with what I got before for the actuator calibration (see this entry).
It means the function is working fine.
||Tue Jun 21 19:54:33 2011
||Suresh||Update||Green Locking||LightWave NPRO power supply shifted to ETMY end table|
The Lightwave NPRO power supply which is being shared between the AS table and the ETMY table has been shifted back to the ETMY table.
The current to the laser is set at 1.5A. The laser output is 200mW at this current level.
||Tue Jun 21 19:10:29 2011
||Suresh||Update||Environment||ETMY end table|
There were small pieces of glass, remnants of a fluorescent tube, which were lying around on the ETMY end table for a while now. We picked up the larger pieces by hand and used the HEPA filtered vacuum cleaner to pick up the remaining glass and dust on the table.
||Tue Jun 21 16:11:13 2011
||steve||Update||SAFETY||surf safety training|
40m surfs: Nicole Ing, Iswita Saikia and Sonali Mohapatra received 40m specific safety training today.
||Tue Jun 21 00:38:21 2011
||Sonali||Update||Green Locking||repositioned "QPDY_PD"|
1.The aim is the laser frequency stabilisation of PSL and AUX.
2.As a first step we want to couple some of the AUX laser beam into a single mode optical fibre and route the fibre to the PSL table.
3.The position of the optical fibre on the ETMY table is shown by the coupler in the attached picture. The yellow lines show the new scheme we want to implement.
4.WHAT WE DID TODAY.
- The Y-arm was locked so that we could use the transmitted IR beam as the reference.
- We shifted the position of the "QPDY_PD" .
- We also shifted the "ETMYT" camera to make space for the "QPDY_PD".
- The mirror directing the beam into the "QPDY_PD" was rotated by 90 degrees to adhere to the new position of the "QPDY_PD".
- The attached photo shows the table as it is right now after the repositioning.
5.We continue with the positioning of the fibre-coupling tomorrow.
||Mon Jun 20 18:36:49 2011
||Suresh||Update||LSC||REFL55 PD update|
I used a matlab code written by Koji to analyse the transimpedance and current noise data of REFL55. The details are in the attached pdf file.
Resonance is at 55.28 MHz:
Q of 4.5, Transimpedance of 615 Ohms
shot noise intercept current = 1.59 mA
current noise =21 pA/rtHz
Notch at 110.78 MHz:
Q of 54.8 Transimpedance of 14.68 Ohms.
REFL55 was modified. The noise level confirmed. The PD is now ready to be installed.
Kevin's measurement report told us that something was wrong with REFL55 PD. The transimpedance looked OK, but the noise level was terrible (equivalent to the shotnoise of 14mA DC current).
Rana and I looked at the circuit, and cleaned up the circuit, by removing unnecessary 11MHz notch, 1k shunt resister, and so on.
I made a quick characterization of the PD.
The transimpedance ws measured as a function of the frequency. The resonance was tuned at 55MHz. The notch was tuned at 110MHz in order to reject the second harmonics. The transimpedance was ~540V/A at 55MHz. (For the calibration, I believed the DC transimpedance of 50V/A and 10000V/A for the DC paths of this PD and #1611, respectively, as well as the RF impedance (700V/A0 of #1611.
Output noise levels were measured with various amount of photocurrent using white light from a light bulb. The measurement was perforemed well above the noise level of the measurement instruments.
The measured output noise levels were converted into the equivalent current noise on the PD. The dark noise level agrees with the shot noise level of 1.5mA (i.e. 22pA/rtHz). In deed, the noise level went up x~1.5 when the photocurrent is ~1.4mA.