Earlier measurements of the modulation index were less than optimal because we had too low transmission through the cavity. Contrary to what was believed you actually need to modematch onto the cavity.
Earlier transmitted power was about 8.5uW.
With a 250mm lens we archived 41uW.
Impinging power on the cavity is 1.7mW.
PD TF approx 0.1V / uW.
Carrier power: 4.1V => 41uW
41uW/1.7mW = 2.4 % transmission. Manufacturer clain for peak transmission: 20-30%.
11MHz SB: 28.8mV => m=0.17
55MHz SB:36mV => m=0.19
As you can see on the pic the SNR of the SBs is not too good.
The following optics were kicked:
Mon Sep 19 15:39:44 PDT 2011
I made the first measurements towards oplev calibration measurements: calibrating the oplevs in SRM YAW. The measurements seemed fine, I had a range of between -1.5 and 1.5 in SRM DC alignment before clipping on mirrors on the oplev bench became a problem. This seemed to be plenty to get a decent fit for the spot position against DC alignment value - see attached plot. The fitted gradient was -420um oplev yaw count. I calculated oplev yaw values as UL+LL-UR-LR. Pitch next.
IPPOS is back. A cable had been disconnected at the 1Y2 rack. So I put it back to place.
The cartoon below shows the current wiring diagram. I think this configuration is exactly the same as it it used to be.
+ Fixing IPPOS (volunteers)
I've got the bench set up for the measurement of the beam spot change with DC SRM alignment offsets. The ITMY oplev is aligned and fine to use, but the SRM one isn't until further notice (probably a couple of hours).
I replaced the lenses that were there with a -150mm lens followed by a +250mm lens. This gave a significantly reduced beam size at the QPDs. With the beam analyzer up and running it should be possible to optimize this later this afternoon. Next I will remove the SRM QPD from the path and make measurements of the beam spot position movement and corresponding OSEM values for different DC mirror offsets. I will then repeat the process for ITMY.
+ Inversion and installation of the SUS input matrices (Jenne)
It turns out that this is complicated, since there are so many people working with the IFO this week. What I would like to do is put in the new input matricies, and then do a free swinging test, to see if the suspensions are really diagonalized in the way that we want them to be. I can't do this during the day, since it will interfere with Paul's OpLev work. And at "night", I can't, since we'll be doing locking. So, this may be a late-night task. I'll write a script this afternoon that will put in all of the new input matricies, and then run the freeswing and the restore watchdogs scripts. Whomever is the last one to leave for the night can run the combo script.
EDIT: As of this time (~11:45am), ITMY has its new input matrix.
GOAL1: Stable lock of DRMI
GOAL2: Measurement of the LSC input matrix in the DRMI configuration
/- - Daytime works - - /
+ Measurement of the arm lengths (Jenne / Kiwamu / volunteers)
+ Optimization of the oplev control loops (Paul)
+ Tuning of the SUS damping gains (Steve)
+ Measurement of the modulation depths (Mirko)
+ Preparation of the green broadband PD (Katrin)
+ Fixing the Y arm green lock servo (Katrin / Kiwamu)
+ Installation of RFPDs (Anamaria)
+ Minimization of the AM sidebands (Anamaria / Keiko)
+ Preparation of a script for measuring the LSC input matrix (Keiko)
+ MC WFS (Suresh)
+ Online adaptive filtering (Mirko / Jenne)
+ Modification of C1ASS (Kiwamu)
+ Auto alignment of PRCL and SRCL (volunteers)
+ Loss measurement of the arm cavities (volunteers)
+ Fixing the ETMX SIDE slow monitor (volunteers)
/- - Nighttime works - - /
+ Locking of DRMI
+ Characterization of DRMI and complete the wiki page
Actually the clipping of POP wasn't in the chamber but it was on the first lens on the optical bench.
So I repositioned the lens to avoid the clipping and now there are no clipping on POP.
We found that POP beam is clipped by the steering mirrors inside the tank.
[Anamaria / Kiwamu]
The incident beam pointing was improved by using PZT1 and PZT2.
With some triggers the lock of PRMI became smoother.
For the DRMI lock, the MICH and SRCL signals on AS55 are not quite decoupled, so we should find cleaner signals for them.
(what we did)
+ locked the Y arm
+ aligned incident beam by using PZT1(#5450) and PZT2. The spot positions on ITMY and ETMY are now well-centered.
+ tried activating C1ASS but failed. It needs some gain changes due to the new PZT1 response.
+ locked the X arm
+ aligned the TRX PD (Thorlab signal PD) and set the trigger.
+ C1ASS also doesn't work for the X arm
+ realigned the PRM and BS oplevs. the PRM oplev was clipped at a steering mirror on the optical bench
+ locked PRMI and aligned the PRM mirror such that the optical gain was maximized
+ optimized the demod phase of AS55 and REFL11
+ checked the UGF of the MICH and PRCL lock. The UGF of MICH is about 100Hz with gain of -20, and the UGF of PRCL was 85 Hz with gain of 0.1
+ adjusted the output matrix such that the MICH control doesn't couple into the PRCL control.
+ set the triggers for the MICH and PRCL control to make the lock acquisition smoother.
+ tried locking DRMI and it was sort of locked. However the SRCL signal showed up a lot in AS55_Q, where the MICH signal is extracted.
The f2a filters were installed on ITMs and ETMX.
Now all of the suspensions has the f2a filters.
Mess in the lab is increasing. Kiwamu and I had to clean up some stuffs to continue our work.
(i.e. some components were disturbing to open the lid of the tables.)
Basically the tools/equipments/component/cables/digital cameras/lens caps/IR viewers
you have used for the day should be cleaned up at the end of the day.
If one likes to leave a temporary stuff, leave a note to indicate by whom, for what, how long
it will be kept like that, and when one is going to back there with contact info like the cell phone #.
The pzt driver for PZT1 has been installed.
As there was unknown resistive connection in the vacuum chamber as described below,
the PZT out cable at the PJ driver module should always be disconnected.
The sensor cables have no problem to be connected to the controller.
In fact, they are a good monitor for the state of the PZTs.
In this configuration, Pitch and Yaw direction of PZT1 is under the control of the EPICS value as we expected.
- At the beginning, we tested the PZT driver output with low voltage level (~10V). We did not see any oscillation of the opamps.
The pitch output was observed to be OK, while the YAW output exhibited a half of the expected output voltage.
The opamp was holding correct voltage, however the voltage after the 1K output resister was about a half.
This indicated there was a voltage division happening.
- The cause of the voltage division was tracked. We found that the yaw red (=hot) line is connected to pitch black
in the vacuum chamber with a resistance of 1.4kOhm. The black cables are shorted to the ground level in the PJ driver.
- We decided to unplug the PJ's cable so that we can isolate the black cables while hoping the PZTs were drived only
by the red and white cables. And they did.
- This means that we should not connect the PZT driving cable to the PJ's driver. The sensors have no problem to be connected.
|. o| 5
|o | 17
| o| 4
|o | 16 Yaw Black
| o| 3 Pitch Black
|o | 15 Yaw White
| o| 2 Yaw Red
|o | 14 Pitch White
\ o| 1 Pitch Red
* Pitch White and Yaw White are connected to the ground at the amplifier side.
* Yaw Red and Pitch Black is connected with 1.4kOhm and isolated from the others.
This modification of the LSC model made the rows of the LSC output matrix shifted. This caused the ASS scripts nonfunctional.
Kiwamu fixed the channel names in the ASS script.
[Jenne, Mirko, with supervision from Jamie]
I modified the c1lsc model to have shmem outputs that go from the degrees of freedom to the OAF, and shmem inputs from the OAF's output to sum into the DoFs, just like Yoichi's FF stuff. I also removed the old OAF_OUT, because it would only allow me to select one DoF at a time, and I will eventually want the ability to do multiple amounts of OAFing at the same time. Hopefully.
We don't need a high quality calibration for the optical levers. ~50% accuracy is fine.
For that you can use the OSEM calibration of ~1.7 V/mm (its less than 2 since the OSEMs have been degrading) or you can use the cavity power method that Kakeru used; it worked just fine. There's no benefit in trying for a 1% number for optical levers.
The PZT driver is now in place. The actual PZTs are not connected yet!
It is accommodated on Ben's connector adapter board.
The panel has additional connectors now: two inputs and a power supply connector.
The supply voltage is +/-30V (actual maximum +/-40V), and the input range is +/-10V
which yields the output range of -5V to 30V. The gain of the amplifier is +2.
It is confirmed that the HV outputs react to the epics sliders although the PZT connector is not connected yet
so as not to disturb the locking activity.
When we engage the PZT connector, we should check the HV outputs with an oscilloscope to confirm they
have no oscillation with the capacitances of the PZTs together with the long cable.
Excited all the optics. They will be automatically back after 5 hours.
Sat Sep 17 02:02:07 PDT 2011
It needs one more kick and free swinging test.
Keiko, Paul, Kiwamu
We found that POP beam is clipped by the steering mirrors inside the tank. POY beam is also likely to be clipped inside. Also the hight of POY beam is too high (about 5 cm higher than the normal paths) at the first lens. These imply the input pointing is bad.
With the new input matrix, it looks like YAW and SIDE are not quite decoupled on ETMX.
- - - details
To see what exactly is going on, I changed the input matrix from the default to the new one, which Jenne computed (#5421) on ETMX.
I started putting the elements of the input matrix from POS through SIDE, one by one.
It seemed that POS and PIT worked fine. However the YAW signal looks containing a lot of the SIDE signal.
Similar to YAW, SIDE also interact with the YAW motion and somehow rings up both YAW and SIDE signals as Jenne reported ( #5438).
So right now the YAW and SIDE rows are partially reburted to the default elements in order to avoid ringing up.
but ETMX and BS were not good at all. ETMX was ringing up when I turned on the damping.
In order to estimate the amount of noise that the oplevs are injecting into the GW channel, we first need to calibrate oplev signals in terms of angular change in the optic. I said in my previous post that there wasn't a calibration factor for OSEM values to radians, but I found that Kakeru had estimated this in 2009 - see entry 1413. However, Kakeru found that this was quite a rough estimate, and that it didn't agree with his calibrated oplev values well. He does quote the 2V/mm calibration factor for the OSEM readings though - does anyone know the provenance of this factor? I searched for OSEM calibration and found nothing.
First of all I moved the lenses on the ITMY/SRM oplev path to get a smaller spot size on the QPDs. I couldn't get the beam analyzer to work though, so I don't know quite how successful this was. The software brought up the error "unable to connect to framegrabber" or something similar. I don't think the signal from the head was being read by the software. I will try to get the beam analyzer working soon so that we can characterize the other oplev lasers and get decent spot sizes on the QPDs. I searched the elog for posts about the analyzer, and found that it has been used recently, so maybe I'm just doing something wrong in using it.
After this I measured the transfer function for the ITMY oplev yaw. I did a swept sine excitation of the ITMY in yaw with an amplitude of 500, and recorded the OSEM yaw values and the oplev yaw values. This should show a flat response, as both the QPD and the OSEMS should have flat frequency response in the measurement band. This measurement should therefore just yield a calibration from OSEM yaw to oplev yaw. If the OSEM yaw values were already calibrated for radians, we would then immediately have a calibration from oplev yaw values to radians. However, as far as I'm aware, there is not a calibration factor available from OSEM yaw values to radians. Anyway, the TF I measured did not appear to be very flat (see attached plot). Kiwamu suggested I should check the correlation between the OSEM measurements and the oplev QPD measurements - if the correlation is less than 1 the TF is not reliable. Indeed the coherence was poor for this measurement. This was probably because at frequencies above the pendulum frequency, the excitation amplitude of 500 was not enough to cause a measurable change in the optic angle. So, the plot attached is not very useful yet, but I learned something while making it.
New channels, POP55 and POY11 are connected to the rack and now available on the data system.
POX11 I is not working. I didn't investigate what was wrong. Please make sure when you come to need POX11.
The orthogonalities of POY11 and POP55 were measured and already adjusted. The results are below:
ABS = 0.973633
PHASE = 92.086483 [deg]
ezcawrite C1:LSC-POY11_Q_GAIN 1.027081 && ezcawrite C1:LSC-POY11_PHASE_D 92.086483
ABS = 1.02680579
PHASE = 88.5246 [deg]
ezcawrite C1:LSC-POP55_Q_GAIN 0.973894 && ezcawrite C1:LSC-POP55_PHASE_D 88.524609
The demodulation phases and gains for the all existing channels, AS11, REFL11,REFL55, REFL165, and REFL33, were adjusted by the command "ezcawrite" commands.
REFL165 ezcawrite C1:LSC-REFL165_Q_GAIN 0.934340 && ezcawrite C1:LSC-REFL165_PHASE_D -81.802479
ezcawrite C1:LSC-REFL33_Q_GAIN 0.984244 && ezcawrite C1:LSC-REFL33_PHASE_D -89.618
The bad medm screens have been fixed. There are no blank fields and all the links are correct.
I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.
The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.
I put the new matricies in from the free swinging test for the: ITMX, ITMY, ETMX, ETMY, PRM, BS
Some of the optics damped okay, but ETMX and BS were not good at all. ETMX was ringing up when I turned on the damping. BS wasn't, but when I gave it a kick, it wouldn't damp. No good.
I tried ITMY, and it was totally fine, with nice damping Qs of ~5. So, I don't know what's going on.
Anamaria is trying a new 4x4 matrix-inverter, so we can look at the inversion of just the face osems. We'll see how it goes.
Since things were crappy, I did a BURT restore, so things are as they were earlier this morning.
I just drew a basic picture of how the ITMX oplev path could be reworked to minimise the number of optics in the path. Only possible problem with this might be the turning mirror onto the ITMX getting in the way of the collimating lenses. Should be easy to solve though. Does anyone know if there is a ITMX pick off beam I should be careful to avoid?
I've calculated a suitable collimating telescope for the ITMY/SRM oplev laser, based on the specs for the soon-to-arrive 2mW laser (model 1122/P) available here: http://www.jdsu.com/ProductLiterature/hnlh1100_ds_cl_ae.pdf
Based on the fact that the 'beam size' value and 'divergence angle' value quoted don't match up, I am assuming that the beam radius value of 315um is _not_ the waist size value, but rather the beam size at the output coupler. From the divergence angle I calculated a 155um waist, (zR = 12cm). This gives the quoted beam size of about 316um at a distance of 8.5" away from the waist. This makes me think that the output coupler is curved and the waist is at the back of the laser, or at least 8.5" from the output coupler.
The collimating telescope gives a waist of size 1142um (zR=6.47m) at a distance of 1.427m away from the original laser waist, using the following lens combo:
L1 f=-0.15 @ 0.301m
L2 f=0.3 @ 0.409m
This should be fine to get a small enough spot size (1-2mm) on the QPDs.
New f2a filters were installed on SRM.
The lock of DRMI should be more stable than last night.
Once the SRM oplev project settles down, I will adjust the f2a filters on SRM too.
Paul, Mirko and Katrin visiting grad students received the 40m basic safety training.
I had to change the c1ioo model and restart the fb since the paths allowing us to select various signals to demodulate using the lockins were not correct. The signal selection vector was not flexible enough to permit us to select the signals to demod.
fb was restarted twice at following times. The changes have been commited to the svn.
Fri Sep 16 13:35:47 PDT 2011
Fri Sep 16 14:36:21 PDT 2011
I checked the dark and bright noise of the SRM oplev QPD. The SRM QPD has a rather high dark level for SUM of 478 counts. The dark noise for the SRM QPD looked a little high in the plot against the bright noise (see first attachment), so I plotted the dark noise with the ITMY QPD dark noise (see second attachment). It seems that the SRM QPD has a much higher dark noise level than the ITMY! In case anyone is wondering, to make these traces I record the data from the pitch and yaw test points, then multiply by the SUM (to correct for the fact that the test point signal has already been divided by SUM). I will check the individual quadrants of the SRM QPD to see if one in particular is very noisy. If so, we/I should probably fix it.
- We have checked the situation of the broken Piezo Jenna PZT (called PZT1)
- Tested PZT1 by applying a dc voltage on the cables. Found that pitch and yaw reasonably moving and the motions are well separated each other.
The pitch requires +20V to set the IPPOS spot on the QPD center.
- Made a high-voltage (actually middle voltage) amp to convert +/-10V EPICS control signal into -5 to +30V PZTout. It is working on the prototype board and will be put into the actual setup soon.
- The Piezo Jenna driver box has 4 modules. From the left-hand side, the HV module, Yaw controller, Pitch controller, and Ben abbot's connector converter.
- We checked the voltage on Ben's converter board. (Photo1)
It turned out that the red cable is the one have the driving voltage while the others stays zero.
- We hooked a 30V DC power supply between the red cable and the shield which is actually connected to the board ground.
- Applying +/-10V, we confirmed the strain gauge is reacting. If we actuated the pitch cable, we only saw the pitch strain gauge reacted. Same situation for yaw too.
- Kiwamu went to IPPOS QPD to see the spot position, while I change the voltage. We found that applying +20V to the pitch cable aligns the spot on the QPD center.
- I started to make a small amplifier boards which converts +/-10V EPICS signals into -5V to +30V PZT outs.
- The OPAMP is OPA452 which can deal with the supply voltages upto +/-40V. We will supply +/-30V. The noninerting amp has the gain of +2.
- It uses a 15V zener diode to produce -15V reference voltage from -30V. This results the output voltage swing from -5V to +35V.
The actual maximum output is +30V because of the supply voltage.
- On the circut test bench, I have applied +/-5V sinusoidal to the input and successfully obtained +5V to +25V swing.
- The board will be put on Ben's board today.
Kiwamu, Keiko, Anamaria
I started today with a different input beam, so I had to realign the REFL path again. Then we measured the RF signal out of the 4 REFL PDs and found them to be too low. We increased the power to around 10mA for each diode, and we can see the right modulation frequency on each diode, though REFL165 is way too weak so we might need an RF amplifier on it. We will measure demod board noise tomorrow.
We had an issue with REFL165 not giving the right DC level, low by a factor of 10, even though it was receiving the same optical power as the others. We fifteen-checked clipping and alignment, then pulled it out and measured it on the test stand - found it to be ok. So I uplugged its power cable at the rack and connected it to the AS165 slot. Problem sloved. Not sure what was wrong with the other power slot.
Then we found REFL55 to be clipping on its black glass, we fixed that. But the REFL55 DC power still changes a lot with seemingly not huge motions of the PRM. We'll investigate more tomorrow.
We added a lens in the path to REFL165 because unlike the others it is a 1mm diode. All diodes have about half a turn to a full turn flatness of maximum (on tiny steering mirror).
We set the whitening gain on all four diodes to 21 db.
Not sure if we should set the power to be different on these diodes since their sensitivity is different to RF, and now REFL11 sees huge signal.
We continued the DRMI locking attempt and brought in the SRC, using AS55I to control it. It kind of works/stays locked. We did manage to get MICH and PRC better controlled than last night, but with SRC in the mix, something is wrong. We have to redo f2a filters on SRM and hopefully things will be better after Jenne's suspension work tomorrow. Oplevs not optimized yet either.
We intend to realign POY beam path so we can monitor power in cavities.
I tried again at plotting the ITMY_QPD noise spectra in for dark and bright operation. Before we had the strange situation where the dark noise seemed higher, but Kiwamu noticed this was caused by dividing by the SUM before the testpoint I was looking at. This time I tried just multiplying by the measured SUM for bright and dark to normalise the spectra against each other. The results looks more reasonable now, the dark noise is lower than the bright noise for a start! However, the dark noise spectrum now doesn't look the same as the one I showed in my previous post.
I changed some colors on the Summary of Suspension Sensor using my italian creativity.
I wrote a script in Python to change the thresholds for the "alarm mode" of the screen.
The script takes a GPS-format start time as the 1st argument and a duration time as the second argument.
For every channel shown in the screen, it compute the mean value during this time.
The 3rd argument is the ratio between the mean and the LOW threshold. The 4th argument is the ratio between the mean and the LOLO threshold.
Then it sets the thresholds simmetrycally for HIGH and HIHI threshold.
It does that for all channels skipping the Gains and the Off Sets because this data are not stored.
For example is ratio are 0.9 and 0.7 and the mean is 10, thresholds will be LOLO=7, LOW=9, HIGH=11, HIHI=13.
You can run the script on pianosa writing on a terminal '/opt/rtcds/caltech/c1/scripts/SUS/set_thresholds.py' and the arguments.
I already run my program with those arguments: 1000123215 600 0.9 0.7
The time is of this morning at 5:00 for 10 minutes
This is the help I wrote
HELP: This program set the thresholds for the "alarm mode" of the C1SUS_SUMMARY.adl medm screen.
Written by Manuel Marchio`, visiting student from University of Pisa - INFN for the 2011 summer at Ligo-Caltech. Thrusday, 15th September 2011.
The 1st argument is the time in gps format when you want to START the mean
The 2nd argument is the DURATION
The 3rd argument is the ratio of the LOW and the HIGH thresholds. It must be in the range [0,1]
The 4th argument is the ratio of the LOLO and the HIHI thresholds. It must be in the range [0,1]
Example: path/set_thresholds.py 1000123215 600 0.9 0.7
and if the the mean is 10, thresholds will be set as LOLO=7, LOW=9, HIGH=11, HIHI=13
I took a dark noise measurement for the ITMY QPD, for comparison with measurements of the oplev noise later on. Initially I was plotting the data from test points after multiplication by the oplev matrix (i.e. the OLPIT_IN1 / OLYAW_IN1), but found that the dark noise level seemed higher than the bright noise level (!?). Kiwamu realised that this is because at that test point the data is already divided by QPD SUM, thus making the dark noise level appear to be greater than the bright level, since QPD SUM is much smaller for the dark measurements. The way around this was to record the direct signals from each quadrant before the division. I took a power spectrum of the dark noise from each quadrant, then added them in quadrature, then divided by QPD SUM at the end to get an uncalibrated PSD. Next I will convert these into the equivalent for pitch and yaw noise spectra. To calibrate the plots in radians per root Hz requires some specific knowledge of the oplev path, so I won't do this until I have adjusted the path.
After Jamie installed the c1oaf model ( entry 5424 ) I went and checked the intermodel communication.
Remember the config is:
c1lsc ->SHMEM-> c1oaf
c1oaf ->SHMEM-> c1lsc
c1pem ->SHMEM-> c1rfm ->PCIE-> c1oaf
I checked at least one of every communications type.
-All signals reach their destinations.
-c1lsc_to_c1oaf_via_shmem is more noisy adding noise to the signal. lsc runs at 16kHz and oaf at 2kHz but that should actually smooth things out.
Just to give some heads up on how the setup on the PSL table does / will look. We start out with one of the two reflections of a window. Power about 2mW.
[Jamie, Jenne, Mirko]
We have installed the new c1oaf (online adaptive feed-forward) model. This model is now running on c1lsc. It's not really doing anything at the moment, but we wanted to get the model running, with all of it's interconnections to the other models.
c1oaf has interconnections to both c1lsc and c1pem via the following routes:
Therefore c1lsc, c1pem, and c1rfm also had to be modified to receive/send the relevant signals.
As always, when adding PCIx senders and receivers, we had to compile all the models multiple times in succession so that the /opt/rtcds/caltech/c1/chans/ipc/C1.ipc would be properly populated with the channel IPC info.
There were a couple of issues that came up when we installed and re/started the models:
When the c1oaf model was started, it had no C1:DAQ-FB0_C1OAF_STATUS channel, as it's supposed to. In the daqd log (/opt/rtcds/caltech/c1/target/fb/logs/daqd.log.19901) I found the following:
Unable to find GDS node 22 system c1oaf in INI files
It turns out this channel is actually created by the frame builder, and it could not find the channel definition file for the new model, so it was failing to create the channels for it. The frame builder "master" file (/opt/rtcds/caltech/c1/target/fb/master) needs to list the c1oaf daq ini files:
These were added, and the framebuilder was restarted. After which the C1:DAQ-FB0_C1OAF_STATUS appeared correctly.
This turned out to be because of an oversight in how we wired up the skeleton c1oaf model. For the moment the c1oaf model has only the PCIx sends and receives. I had therefore grounded the inputs to the SHMEM parts that were meant to send signals to C1LSC. However, this made the RCG think that these SHMEM parts were actually receivers, since it's the grounding of the inputs to these parts that actually tells the RCG that the part is a receiver. I fixed this by adding a filter module to the input of all the senders.
Once this was all fixed, the models were recompiled, installed, and restarted, and everything came up fine.
All model changes were of course committed to the cds_user_apps svn as well.
Just to find out where we are currently, I plotted the ITMY and SRM oplev spectra along with the ETMY oplev spectra. ETMY seems to be very good, so comparing with this seemed useful, so we know how much we have to improve by. The SRM power spectrum appears to be around 2 orders of magnitude higher than ETMY over pretty much the whole measurement band. The ITMY power spectrum is not so bad as the SRM above about 60Hz. Next thing to do is to check the dark noise level for the ITMY and SRM QPDs.
The title of this post should of course have been " ... - comparison with ETMY" not " ... - comparison with ITMY"
All the optcs were excited
Sat Sep 10 02:14:11 PDT 2011
pit yaw pos side butt
UL 0.601 0.680 1.260 -1.009 0.223
UR 0.769 -1.254 -0.175 -0.179 0.581
LR -1.231 0.065 0.566 -0.480 0.252
LL -1.399 2.000 2.000 -1.310 -2.944
SD -0.580 0.868 2.451 1.000 -1.597
pit yaw pos side butt
UL 1.067 0.485 1.145 -0.195 0.929
UR 0.548 -1.515 0.949 -0.142 -1.059
LR -1.452 -0.478 0.855 -0.101 1.051
LL -0.933 1.522 1.051 -0.153 -0.962
SD -0.530 0.903 2.115 1.000 0.142
pit yaw pos side butt
UL 0.842 1.547 1.588 -0.018 1.026
UR 0.126 -0.453 1.843 0.499 -1.173
LR -1.874 -0.428 0.412 0.511 0.934
LL -1.158 1.572 0.157 -0.006 -0.867
SD 1.834 3.513 -0.763 1.000 -0.133
pit yaw pos side butt
UL -0.344 1.280 1.425 -0.024 0.903
UR 1.038 -0.720 1.484 -0.056 -1.161
LR -0.618 -1.445 0.575 -0.040 0.753
LL -2.000 0.555 0.516 -0.007 -1.184
SD -0.047 -0.038 0.986 1.000 0.083
pit yaw pos side butt
UL 1.549 0.655 0.393 0.263 0.997
UR 0.192 -1.345 1.701 -0.063 -0.949
LR -1.808 -0.206 1.607 -0.085 0.952
LL -0.451 1.794 0.299 0.241 -1.101
SD 0.724 0.293 -3.454 1.000 0.037
pit yaw pos side butt
UL 0.697 1.427 1.782 -0.337 0.934
UR 1.294 -0.573 0.660 -0.068 -0.943
LR -0.706 -1.027 0.218 0.016 0.867
LL -1.303 0.973 1.340 -0.254 -1.257
SD 0.369 -0.448 -0.496 1.000 0.456
pit yaw pos side butt
UL 0.872 0.986 0.160 0.054 0.000
UR 0.176 -0.752 0.917 0.018 0.000
LR -1.824 -2.000 1.840 0.002 3.999
LL -1.128 -0.262 1.083 0.038 -0.000
SD 0.041 0.036 -0.193 1.000 -0.001
pit yaw pos side butt
UL 1.042 0.767 0.980 0.131 0.928
UR 0.577 -1.233 1.076 -0.134 -0.905
LR -1.423 -0.640 1.020 -0.146 1.050
LL -0.958 1.360 0.924 0.120 -1.117
SD -0.073 -0.164 -0.702 1.000 -0.056
pit yaw pos side butt
UL 1.595 0.363 1.152 0.166 1.107
UR 0.025 -1.629 1.135 0.197 -0.994
LR -1.975 0.008 0.848 0.105 0.904
LL -0.405 2.000 0.865 0.074 -0.995
SD -0.433 0.400 -1.624 1.000 0.022
Put up a temp. setup on the laser table to measure the RF modulation depths using the optical spectrum analyzer. First with a pickoff beam with about 2mW => SNR of 8 of 1 peak per FSR.
Then with a beam with about 100mW. Much better SNR on the single peak but still no sidebands visible. Modematching not too good in either case. Shouldn't matter.
We have made a new plan for the ITMY and SRM oplev optical path which uses as few optics as possible. This should help to reduce coupling from vibrations of optics in the oplev path back into the GW channel. To get enough room for the turning mirror into the SRM it might be necessary to move the POY optics a bit nearer to the tank.
Today I worked on getting the ITMY and SRM oplevs back in working order. I aligned the SRM path back onto the QPD. I put excitations on the ITMY and SRM in pitch and yaw and observed the beam at the QPDs to check for clipping. They looked clean from clipping.
The f2a filters were newly designed and installed on BS and PRM.
So the lock of PRMI will be more stable .
I changed a filter bank name (C1IOO-WFS1_PIT) in c1ioo model reverting it to its earlier name. Had to restart c1ioo model and the fb
The PRM damping was restored at side sensor var 1050
The PRM sus damping restored.
We were able to lock PRC using REFL11I after improving the MICH dark fringe a bit (moving BS) and rotating AS55 and REFL11 such that the signal was maximized in the phases we were using. The dark port is not so dark... but the lock is stable.
I had finished the whole REFL path alignment, but I didn't have a good input beam reference at the time, which is why we had to realign the PDs and the camera. We only had strength to realign 11 and 55. Otherwise, we just need to tweak and center beam on 33 and 165, figure out what's up with 55 and be done with the AP table mods. I hope.
- We aligned MICH and were successfully locked MICH using AS55Q. The other mirrors were misaligned so that the other degrees of freedom didn't exist. AS55 was fed back to BS. The f2a filters on BS suspension were required to lock, because the pos feedback was unbalanced to angle degrees of freedom.
- We tried to lock PRCL next, however, because we aligned the MICH and the REFL beam paths were changed, REFL PDs didn't have the light anymore. The REFL paths were modified now, so we will try the PRCL locking next.
- We couldn't confirm REFL55 signals although we alined the REFL paths to REFL55 PD.