[Steve / Kiwamu]
An attenuator, consisting of two HWPs and a PBS, has been installed on the PSL table for the MC low power state.
Those items allow us to reduce the amount of the incident power going into the MC.
We haven't decreased the power yet because we still have to measure the arm lengths.
After we finish the measurement we will go to the low power state.
We have adjusted the polarization after the last HWP using another PBS. Now it is S-polarizing beam.
After the installation of the attenuator the beam axis has changed although we were immediately able to lock the MC with TEM00 mode.
I touched two steering mirrors on the PSL table to get the transmitted power of MC higher. At the moment the transmitted power in MC_TRANS is at about 30000 cnts.
The attached picture is the setup of the attenuator on the PSL table.
[Suresh / Kiwamu]
The incident beam power going into MC was decreased down to 20 mW by rotating the HWP that we set yesterday.
A 10% beam splitter which was sitting before MCREFL_PD was replaced by a perfect reflector so that all the power goes into the PD.
And we confirmed that MC can be still locked by increasing C1IOO-MC_REFL_GAIN. Some modifications in the Autolocker script need to be done later.
Also we opened the aperture of the MC2F camera to clearly see the low power beam spot.
WE ARE READY FOR THE VENT !!
Power after the EOM = 1.27 W
Power after the HWPs and PBS = 20.2 mW
Power on MCREFL = 20 mW (MC unlocked)
MCREFL_DC = 0.66 V (with MC locked)
After we finish the measurement we will go to the low power state.
Two extender plates ready for cleaning. The existing optical table tops have 38" OD. Using two of these the OD will be 44"
A comment :
Since the LSC RFPD have a long cable of more than 6 m, which rotates a 33 MHz signal by more than 360 deg, so the delay has always existed in everywhere.
The circuit you measured is a part of the delay existing in the LSC system, but of course it's not a problem as you said.
In principle a delay changes only the demodulation phase. That's how we treat them.
RA: Actually, the issue is not the delay, but instead the dispersion. Is there a problem if we have too much dispersion from the RF filter?
FYI and FMI
Phase tracker UGF is Q_AMP * G * 2 PI / 360 where Q_AMP is the amplitude of the Q_ERR output and G is the gain of the phase tracker.
For example: Q_AMP = 270, G = 4000\ => UGF = 1.9kHz
[Koji, Jenne, Yuta]
We put phase tracker in FINE loop for ALS. We checked it works, and we scanned Y arm by sweeping the phase of the I-Q rotator.
From the 8 FSR scan using FINE (30 m delay line), we derived that Y arm finesse is 421 +/- 6.
What we did:
1. We made new phase rotator because current cdsWfsPhase in CDS_PARTS doesn't have phase input. We want to control phase. New phase rotator currently lives in /opt/rtcds/userapps/trunk/isc/c1/models/PHASEROT.mdl. I checked that this works by sweeping the phase input and monitoring the IQ outputs.
2. We made a phase tracker (/opt/rtcds/userapps/trunk/isc/c1/models/IQLOCK.mdl) and included in c1gcv model. Unit delay is for making a feed back inside the digital system. Currently it is used only for BEATY_FINE (Simulink diagram below). We edited MEDM screens a little accordingly.
3. Phase tracking loop has UGF ~ 1.2 kHz, phase margin ~50 deg. They are enough becuase ALS loop has UGF ~ 100 Hz. To control phase tracking loop, use filter module C1:ALS-BEATY_FINE_PHASE (with gain 100). Sometimes, phase tracking loop has large offset because of the integrator and freedom of 360*n in the loop. To relief this, use "CLEAR HISTORY."
4. Locked Y arm using C1:ALS-BEATY_FINE_PHASE_OUT as an error signal. It worked perfectly and UGF was ~ 90 Hz with gain -8 in C1:ALS-YARM filter module.
5. Swept phase input to the new phase rotator using excitation point in filter module C1:ALS-BEATY_FINE_OFFSET. Below is the result from this scan. As you can see, we are able to scan for more than the linear range of FINE_I_IN1 signal. We need this extra OFFSET module for scanning because BEATY_FINE_I_ERR stays 0 in the phase tracking loop, and also, error signal for ALS, output of PHASE module, stays 0 in ALS loop.
6. We analyzed the data from 8FSR scan by FINE with phase tracker using analyzemodescan.py (below). We got Y arm finesse to be 421 +/- 6 (error in 1 sigma). I think the error for the finesse measurement improved because we could done more linear sweep using phase tracker.
Next things to do:
- Phase tracker works amazingly. Maybe we don't need COARSE any more.
- Install it to X arm and do ALS for both arms.
- From the series of mode scan we did, mode matching to the arm is OK. There must be something wrong in the PRC, not the input beam. Look into PRC mode matching using video capture and measuring beam size.
We found that our phase tracker noise is currently limited by the noise introduced in DAQ.
We confirmed that the frequency noise was improved from 2 Hz/rtHz to 0.4 Hz/rtHz by increasing the gain of the whitening filter.
The whitening filters should definitely be refined.
What we did:
1. Put constant frequency RF input to the beatbox from Marconi and measured noise spectrum of the beatbox output(BEATX I) after the whitening filter with a spectrum analyzer. Noise floor level was ~0.2 Hz/rtHz at carrier frequency range of 15-100 MHz. Calibration factor of the beatbox output was ~380 mV/MHz.
2. Measured noise spectrum of C1:ALS-BEATX_FINE_I_OUTPUT(figure below). The noise floor didn't change when there was RF input of 100 MHz from Marconi(blue) and DAQ input was terminated (green). Also, C1:ALS-BEATX_FINE_I_IN1(which is before unwhitening filter) showed a flat spectrum. These show our spectrum is limited by DAQ noise, which is introduced after the whitening filter.
3. We increased the gain of whitening filter by x20 to show frequency noise performance can be improved by better whitening filter(red). But we can not use this setup as the other quadrature will be saturated by a too much gain at DC. Thus we need to carefully consider the signal level and the gain distribution of the whitening filters.
- Better whitening filters. The current one consists of zero 1 Hz and pole 10 Hz with DC gain of 5 using SR560.
- Better beatbox. We can increase the RF input power to the mixer and unify the preamplifier and the whitening filter in the box.
I measured openloop transfer function of the phase tracking loop for the first characterization of phase tracker.
What is phase tracker:
See elog #6832.
For ALS, we use delay-line frequency discriminator, but it has trade-off between sensitivity and linear range. We solved this trade-off by tacking the phase of I/Q signals.
Figure below is the current diagram of the frequency discriminator using phase tracker.
OLTF of phase tracking loop:
Below. UGF at 1.2 kHz, phase margin 63 deg for both BEATX and BEATY. Phase delay can be clearly explained by 61 usec delay. This delay is 1 step in 16 KHz system.
Note that UGF depends on the amplitude of the RF input. I think this should be fixed by calculating the amplitude from I/Q signals.
BEAT(X|Y)_PHASE_GAIN were set to 300, and I put -3dBm 100 MHz RF signal to the beatbox during the measurement.
Other measurements needed:
- Linear range: By sweeping the RF input frequency and see sensitivity dependence.
- Bandwidth: By measuring transfer function from the modulation frequency of the RF input to phase tracker output.
- Maximum sensitivity: Sensitivity dependence on delay-line length (see PSL_Lab #825).
- Noise: Lock oscillator frequency with phase tracker and measure out-of-loop frequency noise with phase tracker.
- Sensitivity to amplitude fluctuation: Modulate RF input amplitude and measure the sensitivity.
I swept the frequency of RF input to the beatbox to calibrate and check linearity range of phase tracker.
Calibration factors are;
C1:ALS-BEATX_FINE_PHASE_OUT 52.1643 +/- 0.0003 deg/MHz
C1:ALS-BEATY_FINE_PHASE_OUT 51.4788 +/- 0.0003 deg/MHz
There was systematic error to the linearity check, but at least, calibration factor changes less than 50 % in the frequency range of 10 MHz to more than 500 MHz.
What I did:
Used network analyzer(Aligent 4395A) to sweep the frequency RF input to the beatbox and getdata of phase tracker signal. I swept from 10 Hz to 500 MHz with 501 points in 50 sec. This sweep is slow enough considering we could lock the 40m arms (typical speed of a mirror is 1 um/s, so bandwidth of the phase tracker should be more than 1 um/sec / 40 m * 3e14 Hz = 75 MHz/s).
RF amplitude was set to be -3 dBm and splitted into BEATX and BEATY.
Plots for BEATX and BEATY are below;
- Considering delay line length is ~30m, expected calibration factor is;
2*pi*l/v = 2*pi * 30 m / (2e8 m/s) = 0.94 rad/MHz = 54 deg/MHz
so, this calibration is reasonable.
- Since frequency sweep of network analyzer is not continuous, phase tracker output is like steps with some ringdown. This makes some systematic error for checking linearity. I'm planning to do slower sweep or continuous sweep. Also, the phase tracker seems like he can exceed 500 MHz.
I measured noise level of the phase tracker by inputting constant frequency RF signal from marconi.
Measured frequency noise was ~2 Hz/rtHz @ 100 Hz. It's not so good.
What I did:
1. Unplugged 11MHz marconi and put RF signal to the beatbox from this. Frequency and amplitude I put are 100 MHz and -3 dBm.
2. Measured spectra of phase tracker outputs, C1:ALS-BEATX_FINE_PHASE_OUT, C1:ALS-BEATY_FINE_PHASE_OUT.
3. Calibrated using the factor I measured (elog #8199).
4. Put marconi back to orignal settings.
- According to Schilt et al., this noise level is not so good.
- By changing the delay-line cable length or optimizing whitening filter etc., we can improve this.
Since lately the alignment of the input beam to the interferometer has changed, I went checking the alignment of the beam on the photodiodea. They were all fine except for pd9, that is AS DD 199. Here the DC is totally null. The beam seems to go right on the diode but the scope on the PD's DC output shows no power. This is really strange and bad.
After inspecting PD9 with the viewer and the cards, the beam looks like it is aligned to the photodiode althought there is no signal at the DC output of the photodetector. So I checked the spectrum for PD9_i and Q (see attachments) and it seems that those channels are actually seeing the beam. I'm going to check the alignemtn again and see the efefct on the spectra to make sure that the beam is really hitting the PD.
Message on 'pianosa':
Failed to fetch http://ppa.launchpad.net/drgraefy/nds2-client/ubuntu/dists/lucid/main/binary-amd64/Packages.gz 404 Not Found
Sorry, that was an experiment to see if I could set up a general-use repository for the NDS packages. I've removed it, and did an update/upgrade.
I decided to remove what I thought was the problematic extra nVidia video card, since there are already two DVI outputs build-in. The card turned out to not even be nVidia, so I don't know what was going on there.
I futzed with the BIOS to configure the primary video card, which is some new Intel card. The lucid (10.04) support for it is lacking, but it was easy enough to pull in new drivers from the appropriate Ubuntu PPA repository:
controls@pianosa:~ 0$ sudo apt-add-repository ppa:f-hackenberger/x220-intel-mesa
controls@pianosa:~ 0$ sudo apt-add-repository ppa:glasen/intel-driver
controls@pianosa:~ 0$ sudo apt-get update
controls@pianosa:~ 0$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
libdrm-intel1 libdrm-nouveau1 libdrm-radeon1 libdrm2 libgl1-mesa-dri libgl1-mesa-glx libglu1-mesa xserver-xorg-video-intel
8 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 3,212kB of archives.
After this operation, 25.2MB disk space will be freed.
Do you want to continue [Y/n]?
After a reboot, both monitors came up fine.
MEDM, EPICS and dataviewer seem to work, but diaggui still doesn't work (it doesn't work on Rossa either, same problem as reported here, does a fix exist?). So looks like only donatella can run diaggui for now. I had to disable the systemd firewall per the instructions page in order to get EPICS to work. Also, there is no MATLAB installed on this machine yet. sshd has been enabled.
One of the pianosa monitors has ceased to function For now, it has been set up to operate with just the one monitor.
One of Donatella's monitors has a defective display as well. Maybe we should source some replacements. Koji has said we will talk to Larry Wallace about this..
We obtained two monitors of the same type from Larry.
pianosa has been upgraded to SL7. I've made a controls user account, added it to sudoers, did the network config, and mounted /cvs/cds using /etc/fstab. Other capabilities are being slowly added, but it may be a while before this workstation has all the kinks ironed out. For now, I'm going to follow the instructions on this wiki to try and get the usual LSC stuff working.
DASWG is not what we want to use for config; we should use the K. Thorne LLO instructions, like I did for ROSSA.
We have installed the pick-off mirror at the ETMY table for the small-angle scattering measurement on ITMY. As we had already done for the X arm pick-off, the pick-off mirror at ETMY was aligned shooting a green laser normally through the viewport on the pick-off and steering it onto ITMY.
A baffle was also installed at a distance of about 30cm from ETMY near the edge of the table.
The pictures that we took are now on the Picasa web site. Check it out.
Also, we took photos (to be posted on Picasa in a day or two) of all the main IFO magnet-in-OSEM centering, as best we could. SRM, BS, PRM all caused trouble, due to their tight optical layouts. We got what we could.
I uploaded some pictures taken in the last and this week. They are on the Picasa web albums.
in vac work [Nov. 18 2010]
in vac work [Nov 23 2010]
CDS work [Nov 24 2010]
In ----o-------- | | --------o-------- Out
_ 1uF R 7.5 kOhms
After much googling, I figured out how to install pip on SL7:
sudo easy_install pip
Next, I installed git:
sudo yum install git A
Turns out, actually, pip can be installed via yum using
sudo yum install python-pip
Yesterday, we aligned the Faraday and the beam reached SM2 at BS table.
Today, we placed a new PRM tower to BS table.
What we did:
1. Moved IPPO, IPPOSSM1, IPPOSSM3, IPANGSM1, IPANGSM2 out from the BS chamber.
2. Moved SRM tower(at PRM's place) to the ITMX chamber.
3. Placed the new PRM tower at the BS chamber.
4. Adjusted positions of the OSEMs for PRM and BS so that the sensor output can have roughly half of their maximum.
5. Checked damping servo for PRM and BS. They were working and helped us when adjusting OSEM positions.
6. Placed IPPO back and using SM2, made the beam hit PR2 at ITMX table.
7. Aligned the PRM so that the reflected beam path overlaps the incident beam.
We checked it by looking at MMT1.
For the alignment, we used IFO align sliders(C1:SUS-PRM_PIT_COMM, YAW_COMM).
To use them, we rebooted c1susaux.
1. The new PRM tower is placed.
2. OSEM sensor outputs for PRM and BS are;
We changed PRM aligning slider values, and they changed OSEM sensor outputs. We set the slider values to 0 when adjusting OSEM positions.
On Friday, Koji and I adjusted the beam pointing into the DRMI using the PZT yaw and found that the beam inside the DRMI (as seen on the AS camera) looked OK (not distorted too much).
So it seems that the issue seen before, namely that the DRMI resonant mode is very strange, is no longer true.
The camera image at the AS port still looks elliptical. So Jenne and Mike have started to make this beam round by adjusting the lenses.
Our plan now is:
1) Fix AS camera optics to get a round beam (single bounce off of ITMY).
2) Flash DRMI to make sure the beam at AS is still round.
3) Using the moveable Watec camera and Sensoray, get images of the spot on all DRMI mirrors with DRMI flashing. Use targets and rulers whenever possible to get quantitative measurements of the beam positions. (i.e. just saying "Oh, its pretty much in the center" is the Mickey Mouse approach to science)
4) Align all pickoff beams in this situation. Make sure there is no in vac clipping. Align IP POS and ANG using this input beam pointing.
5) Pump down.
Some tasks for the daytime tomorrow.
* Beam profile measurements of the Y end laser (Suresh / Bryan)
* Taking care of CDS and the simulated plant (Jamie / Joe)
* Reconnect the X end mechanical shutter to 1X9 (Kiwamu)
* LPF for the X end temperature feedback (Larisa)
I summarized how we proceed our green locking in this month on the wiki.
Since step1 and 2 shown on the wiki are mostly done apparently, so we will move on to step 3-D and 3-E.
A short term target in the coming couple of days is to phase lock the VCO to the beat note.
- Plan for this week
* Intensity stabilization for the end green laser (Matt / Kiwamu)
* Hand off the servo from Green to Red (Matt / Kiwamu)
* Y end green locking (Suresh / Bryan) (rough schedule)
* Reconnect the X end mechanical shutter to 1X9 (Kiwamu)
* Connect the end DCPD signal to a DAC (done)
* Make a LPF in a Pomona box for the temperature (Larisa)
* Clean up and finalize the X end setup (Kiwamu)
* Make a item lists for electronics. Order the electronics. (Aidan / Kiwamu)
Here are a few things I will be working on:
- Plan for tomorrow
* Video cable session (I need ETMY_TRNAS) (team)
* Characterization of the Y end laser (Bryan / Suresh)
* LPF for the X end laser temperature control (Larisa)
* Frequency Divider (Matt)
* X end mechanical shutter (Kiwamu)
Notes of stuff we discussed @ today's meeting, and afterwards, towards measuring ponderomotive squeezing at the 40m.
This entry is meant to be a sort of inventory check and a tentative plan-of-action for the installation of the PZT mounted mirrors and associated electronics on the Y-endtable.
High-Voltage Power Supply
Situation at rack 1Y4
This is an update on the situation as far as PZT installation is concerned. I measured the required cable (PZT driver board to PZT) lengths for the X and Y ends as well as the PSL table once again, with the help of a 3m long BNC cable, just to make sure we had the lengths right. The quoted cable lengths include a meter tolerance. The PZTs themselves have cable lengths of 1.5m, though I have assumed that this will be used on the tables themselves. The inventory status is as follows.
I also did a preliminary check on the driver boards, mainly to check for continuity. Some minor modifications have been made to this board from the schematic shown here (using jumper wires soldered on the top-side of the PCB). I will have to do a more comprehensive check to make sure the board as such is functioning as we expect it to. The plan for this is to first check the board without the high-voltage power supply (using an expansion card to hook it up to a eurocrate). Once it has been verified that the board is getting powered, I will connect the high-voltage supply and a test PZT to the board to do both a check of the board as well as a preliminary calibration of the PZTs.
To this end, I need something to track the spot position as I apply varying voltage to the PZT. QPDs are an option, the alternative being some PSDs I found. The problem with the latter is that the interfaces to the PSD (there are 3) all seem to be damaged (according to the labels on two of them). I tried connecting a PSD to the third interface (OT301 Precision Position Sensing Amplifier), and hooked it up to an oscilloscope. I then shone a laser pointer on the psd, and moved it around a little to see if the signals on the oscilloscope made sense. They didn't on this first try, though this may be because the sensing amplifier is not calibrated. I will try this again. If I can get one of the PSDs to work, mount it on a test optical table and calibrate it. The plan is then to use this PSD to track the position of the reflected beam off a mirror mounted on a PZT (temporarily, using double sided tape) that is driven by feeding small-amplitude signals to the driver board via a function generator.
The LEMO connector on the PZTs have the part number LEMO.FFS.00, while the male SMB connectors on the board have the part number PE4177 (Pasternack)
Plan of Action:
The wiring scheme has been modified a little, I am uploading an updated one here. In the earlier version, I had mistaken the monitor channels as points from which to log data, while they are really just for debugging. I have also revised the coaxial cable type used (RG316 as opposed to RG174) and the SMB connector (female rather than male).
Today's main mission is : adjustment of the arm length
+ Open the ETMX(Y) door, starting from 9:00 AM
+ Secure the ETMX(Y) test mass by tightening the earthquake stops.
+ Move the ETMX(Y) suspension closer to the door side
+ Inspect the OSEMs and take pictures before and after touching the OSEMs.
+ Level the table
+ Adjust the OSEM positions
+ Move the ETMX(Y) suspension to have designed X(Y)arm length
+ Level the table again
+ Align the ETMX(Y) such that the green beam resonate
[Joe, Suresh, Kiwamu]
We will fully install and run the new C1LSC front end machine tomorrow.
And finally it is going to take care of the IOO PZT mirrors as well as LSC codes.
During the in-vac work today, we tried to energize and adjust the PZT mirrors to their midpoints.
However it turned out that C1ASC, which controls the voltage applying on the PZT mirrors, were not running.
We tried rebooting C1ASC by keying the crate but it didn't come back.
The error message we got in telnet was :
memory init failure !!
We discussed how to control the PZT mirrors from point of view of both short term and long term operation.
We decided to quit using C1ASC and use new C1LSC instead.
A good thing of this action is that, this work will bring the CDS closer to the final configuration.
(things to do)
- move C1LSC to the proper rack (1X4).
- pull out the stuff associated with C1ASC from the 1Y3 rack.
- install an IO chasis to the 1Y3 rack.
- string a fiber from C1LSC to the IO chasis.
- timing cable (?)
- configure C1LSC for Gentoo
- run a simple model to check the health
- build a model for controlling the PZT mirrors
The electrical shop has to connect the new power transformer at CES. This means we will have no AC power for ~8 hrs on Saturday, February 20
Is this date good for us to power down ALL equipment in the lab?
Guralp Vert1b and Guralp EW1b are plugged back in to PEM ADCU #10 and #12 respectively. Guralp NS1b remains plugged in. So, PEM-SEIS_MC1_X,Y,Z should now corrsp to seismometer as before.
[Manuel, Ishwita, Jenne, Jamie]
We changed the C1PEM model and the names of the C1:PEM channels.
We reinstalled the blue breakout box, since the purple one still didn't work.
So, now the AA board channels are connected as follows...
C1 = C1:PEM-SEIS_GUR1_X
C2 = C1:PEM-SEIS_GUR1_Y
C3 = C1:PEM-SEIS_GUR1_Z
C4 = C1:PEM-SEIS_GUR2_X
C5 = C1:PEM-SEIS_GUR2_Y
C6 = C1:PEM-SEIS_GUR2_Z
C7 = C1:PEM-SEIS_STS_1_X
C8 = C1:PEM-SEIS_STS_1_Y
C9 = C1:PEM-SEIS_STS_1_Z
C11 = C1:PEM-SEIS_STS_2_X
C12 = C1:PEM-SEIS_STS_2_Y
C13 = C1:PEM-SEIS_STS_2_Z
C14 = C1:PEM-SEIS_STS_3_X
C15 = C1:PEM-SEIS_STS_3_Y
C16 = C1:PEM-SEIS_STS_3_Z
C17 = C1:PEM-ACC_MC1_X
C18 = C1:PEM-ACC_MC1_Y
C19 = C1:PEM-ACC_MC1_Z
C20 = C1:PEM-ACC_MC2_X
C21 = C1:PEM-ACC_MC2_Y
C22 = C1:PEM-ACC_MC2_Z
Although the channels for all 3 STS-2 seismometers are made but only one is installed. So only Channels C1 to C9 are now in operation...
We checked the data from the plugged channels with the Dataviewer. We could see the peak whenever someone jumped in the lab. Even Kiwamu jumped and saw his signal.
I put the PMC last mode matching lens (one between the steering mirrors) on a translation stage to facilitate the PMC mode matching.
Currently 4% of incident power is reflected by the PMC. But the reflected beam does not look "very professional" on the camera to Rana - meaning there is too much TEM20 (bulls eye) mode in the reflected beam.
I locked the PMC on bulls eye mode and measured the ratio of the TEM20/TEM00 in transmission to be 1.3%. Thus the PMC mode matching is ~99% and the incident beam HOM content is ~3%.
While working on the PMC I found that the source of PMC "blinking" is not the frequency control signal from MC to the laser (the MC servo was turned off) but possibly some oscillation which could be affected even by a small change of the pump current 2.10 A to 2.08 A. I showed this behaviour to Kiwamu and we decided to leave the the current at 2.08 A for now where things look stable and investigate later.
Tonight I noticed that the drop in PMC transmission was ~1V, more than the usual of ~0.5V from the daily drift.
While re-aligning on the table, I noticed that the misalignment was not from either of the steering mirrors; i.e. I has to walk them both to get the alignment back. This implies that the misalignment is generated far upstream. Maybe the the laser itself is moving. We need some updates from Steve's laser misalignment tracker.
I'd like to replace the paper target with IOO -QPD_POS so we can log it.