The MC_trans QPD Pitch and Yaw readout on the Lock_MC screen are now normalized by the trans_sum. I used the method described in my entry elog 1488.
/caltech/target/c1iool0/ioo.db now includes:
field(SCAN, ".1 second")
field(SCAN, ".1 second")
The Lock_MC screen was changed to show these new P and Y channels.
Yesterday we found that the channel C1:MDP-POS_EXC looked distorted and had what appeared to be doubled frequency componenets, in the dataviewer. This was because the dcu_rate in the file /caltech/target/fb/daqdrc was set to 16K while the adl file was set to 32K. When daqdrc was corrected it was fixed. I am going to recompile and run all these models at 16K. Once the 40 m moves over to the new front end system, we may find it advantageous to take advantage of the faster speeds, but maybe it's a good idea to get everything working at 16K first.
Last night Rana noticed that the overflows on the ITM and ETM coils were a crazy huge number. Today I rebooted c1dcuepics, c1iovme, c1sosvme, c1susvme1 and c1susvme2 (in that order). Rob helped me burt restore losepics and iscepics, which needs to be done whenever you reboot the epics computer.
Unfortunately this didn't help the overflow problem at all. I don't know what to do about that.
Just start by re-setting them to zero. Then you have to figure out what's causing them to saturate by watching time series and looking at spectra.
We put a simple pendulum into the MDP model, and everything communicates. We're still having some kind of TP or daq problem, so we're still in debugging mode. We went back to 32K in the .adl's, and when driving MDP, the MDC-ETMX_POS_OUT is nasty, it follows the sine wave envelope but goes to zero 16 times per second.
The breakout boards have arrived. The plan is to fix this daq problem, then demonstrate the model MDC/MDP system. Then we'll switch to the "external" system (called SAM) and match control TF to the model. Then we'd like to hook up ETMX, and run the system isolated from the rest of the IFO. Finally we'd like to tie it into the IFO using reflective memory.
After the mini boot fest that Jenne did today, I checked whether that fixed the overflow issues we yesterday prevented the alignemnt of the arms.
I ran the alignment script for the arms getting 0.85 for TRX and 0.75 for TRY: low values.
After I ran the script ,C1SUSVME1 and C1SUSVME2 started having problems with the FE SYNC (counter at 16378). I rebooted those two and fix the sync problem but the transmitted powers didn't improve.
Are we still having problem due to MC misalignment?
I have spent the past couple of days gathering optics and mounts so that I can observe the modulation of the EOM attached to the circuit I built using the optical spectrum analyzer (OSA). A rough diagram of the planned layout is attached.
I also built a short SMA cable so that the EOM did not have to be connected directly to the circuit box. The cable is shown attached to the EOM and circuit box in the attached photo. After checking to make sure that all of the connections in the cable were sound, I remeasured the input impedance of the circuit; the impedance measurement (black) is shown in the attached plot with the impedance before the SMA cable was added with and without the box (green and blue, respectively--these two are almost identical). The new impedance has a strange shape compared to the original measurements; I'd like to understand this a little better, since adding extra inductance in LTSpice doesn't seem to have that effect. Since I had already taken apart the setup used for the previous impedance measurements, I had to rebuild and recalibrate the setup; I guess the difference could be something about the new calibration, but I don't really think that that's the case.
I have spent the past couple of days gathering optics and mounts so that I can observe the modulation of the EOM attached to the circuit I built using the optical spectrum analyzer (OSA). A rough diagram of the planned layout is attached.
After investigating this a bit further, I discovered that some of the components in the circuit were pressed firmly up against the inside of the box, and when they were moved, the impedance plot changed shape dramatically. I think that originally, the components were not pressed against the box, but the box's SMA joint was rather loose; when I connected this to the SMA cable, I tightened it, and this seems to have twisted the circuit around inside the box, pushing the components up against the side. I have fixed the twisting, and since the SMA joint is now tight, the circuit should no longer have any twisting problems.
A new plot is attached, showing the impedance of the circuit with nothing attached (blue), with the SMA cable and EOM attached (green), and with the EOM attached directly to it taken last friday with the old calibration of the setup (red). All three curves look roughly the same; the center peak is shifted slightly between the three curves, but the circuit with SMA and EOM is the version we'll be using, and it's central peak is close to the correct value.
The daq on megatron was nuts. Alex and I discovered that there was no gds installation for site_letter=C (i.e. Caltech) so the default M was being used (for MIT). Apparently we are the first Caltech installation. We added the appropriate line to the RCG Makefile and recompiled and reinstalled (at 16K). Now DV looks good on MDP and MDC, and I made a transfer function that replicates bounce-roll filter. So DTT works too.
The 40m-IFO vacuum envelope doors are sealed with dual viton O-rings and they are pumped through the annulos lines.
This allows easy access into the chambers. The compression of the o-rings are controlled by the o-ring grooves.
The OOC (output optic chamber)'s west side door has no such groove and it is sealed by just one single O-ring.
We have to protect this O-ring from total compression by 3 shims as shown below.
There were control shims in place before and they disappeared.
Let's remember that these shims are essential to keep our vacuum system in good condition.
I've now also trended the MOPA output power for the last 200 days to check a possible correlation with the FSS reflected power. See attachment.
The trend shows that the laser power has decayed but it seems that the FSS reflected power has done it even faster: 30% drop in the FSS vs 7% for the MOPA in the last 60 days (attachment n.2).
Here we trended also the PMC and the MZ. The drop in the PMC happens at the same rate as the MOPA's.
That let us think that the FSS transmitteed power has gone down because of the reference cavity progressive misalignment to the laser beam.
We need to adjust that alignment sometime.
The drop in the NPRO output power (upper row, 3rd plot: Ch10 C1:PSL_126MOPA_126MON) accompained an increase of "fuzziness" in PMCTRANSPD and both coincided in time with the day we tempoarirly removed the flap from the laser chiller's chiller (July 14 2009).
Stephanie has needed the doors to the PSL open all day, and still has them open, so I just turned the HEPAs on high.
For the past week Dmass and I have been ordering parts and getting ready to construct our own modified version of EUCLID (figure). Changes to the EUCLID design could include the removal of the first lens, the replacement of the cat's eye retroreflector with a lens focusing the beam waist on a mirror in that arm of the Michelson, and the removal of the linear polarizers. A beam dump was added above the first polarizing beam splitter and the beam at Photodetector 2 was attenuated with an additional polarizing beam splitter and beam dump. Another proposed alteration is to change the non-polarizing beam splitter from 50/50 to 33/66. By changing the reflectivity to 66\%, less power coming into the non-polarizing beam splitter would be ``lost" at the reference detector (1/3 instead of 1/2), and on the return trip less power would be lost at the polarizing beam splitter (1/6 instead of 1/4). Also, here's a noise plot comparing a few displacement sensors that are used to the shot noise levels for the three designs I've been looking at.
I thought slightly harder and I think that the beamsplitter stays. We will lose too much power on the first PD if we do that:
33/66: Pwr @ PD2 = 2/3*1/3*1/2 = 1/9 Pin
Pwr @ PD3 = 2/3*2/3*1/2 = 2/9 Pin
50:50 Pwr @ PD2 = PWR @ PD3 = 1/8 Pin
balancing them is probably better.
We aligned both the reference cavity and the PMC, each by looking at their Trans PD on Davaviewer, and adjusting the two steering mirrors to maximize the transmission power. We got a pretty good amount of improvement for the ref cav, but since the PMC hasn't decayed a whole lot, we got a much smaller amount of improvement.
I turned the HEPAs back down to ~50.
Stephanie and Koji
We left two carts near the PSL table.
We are using them for characterization of the tripple resonant EOM.
After Alberto and I worked on aligning the reference cavity, Rob asked the important and useful question: what is the visibility of the reference cavity. This helps tell us if we're optimally aligned or not even close.
I did a scan of the ref cav temperature, using /scripts/PSL/FSS/SLOWscan, but there seems to be no real signal is C1:PSL-FSS_RFPDDC. As shown in Alberto's 200-day plot, it does change sometimes, but if you zoom in on the flat parts, it seems like it's not really reading anything meaningful. I did a cursory check-out of it, but I'm not 100% sure where to go from here: There are (as with all of these gold-box PDs) 3 outputs: a ribbon cable (for ADC purposes I think), an SMA for the RF signal, and a BNC for the DC signal. The photodiode is clearly working, since if you stick the Lollypop in front of the PD, the cavity unlocks. I plugged a 'scope into the DC BNC, and it also behaves as expected: block the beam and the signal goes down; unblock the beam and the signal goes up. Something of note is that this readout gives a positive voltage, which decreases when the beam is blocked. However, looking at the dataviewer channel, nothing at all seems to happen when the beam is blocked/unblocked. So the problem lies somewhere in the get-signal-to-DAQ path. I unplugged and replugged in the ribbon cable, and the value at which the channel has been stuck changed. Many days ago, the value was -0.5, for the last few days it's been -1.5, and after my unplug/replug, it's now back to ~ -0.5 . The other day Alberto mentioned, and made the point again today that it's a little weird that the PD reads out a negative voltage. Hmm.
we have a tester cable, but you don't want it. Instead the problem is probably at the cross-connect. The D-cable goes to a cross-connect and you can probe there with a voltmeter. If the signal is good there, trace it to the ADC. Also trend for several years to see when this happened - Yoichi may know the history better.
Also, we still need to complete the FSS RFPD task list from last year.
For some reason a few minutes ago the FB DAQ crashed and I had to restarted.
Today I was able to make low frequency transfer function with DTT on megatron. There seems to have been a timing problem, perhaps Alex fixed it or it is intermittent.
I have attached the open loop transfer function for the un-optimized system, which is at least stable to step impulses with the current filters and gains. The next step is to optimize, transfer this knowledge to the ADC/DAC version, and hook it up to isolated ETMX.
After many issues, I finally have some Guralp box noise. I did not measure every single channel with high resolution at the low frequencies because that would have taken about 3 years, but I could perhaps take some faster measurements for all of them if necessary.
I called in the reinforcements today. Ben came over and we looked all around at all of the cross-connects and cables relating to the FSS. Everything looks pretty much okey-dokey, except that we still weren't getting signal in the DataViewer channels. Finally we looked at the psl.db file, which indicates that the C1:PSL-FSS_RFPDDC channel looks at channel 21 of the ADC cross connect thing. We followed the cable which was plugged into this, and it led to a cable which was disconnected, but laying right next to the Ref Cav refl PD. We plugged this into the DC out SMA connection of the photodiode (which had not been connected to anything), and suddenly everything was mostly golden again in dataviewer land. RFPDDC_F now has a signal, but RFPDDC is still flat.
Even though this seems to be working now, it's still not perfect. Rob suggested that instead of having this SMA cable going from the photodiode's DC out, we should take the signal from the ribbon cable. So I'm going to figure out which pin of the D-connector is the DC out, and take that from the cross connect to the ADC cross connect. This will help avoid some persnickity ground loops.
Shown below are the plots of the amplitude and phase of the Mephisto laser light modulated with a chopper as a square wave at about 1 kHz. The color bar for the phase should run from -pi to pi, and it does when I don't accidently comment out the color bar function. Anyway, the phase is consistently pi/4 or pi/4 plus or minus pi. Usually all three of these phases occur within the same image, as shown below. Also, the amplitude is a factor of two or so higher than it should be where this phase jump occurs. I think these problems are associated with the nature of the square wave. However, there is a software bug that appears to be independent of the input data: there is a rounding error that causes the amplitude to jump to infinity at certain points. This happened for only a dozen or so pixels so I deleted them from the amplitude plot shown below. I am currently working on a more robust code that will use the Newton-Raphson method for nonlinear systems of equations.
The images that I just posted were taken with the CMOS camera. We switched from the CCD to the CMOS because the CCD was exhibiting much higher blooming effects. Unlike the CCD, there is a slight background structure if you look carefully in the amplitude image, but I can correct for this consistent background by taking a uniformly exposed image by placing a convex lens in front of the CMOS. I will then divide each frame taken of the laser wavefront by the background image.
Both Guralps and the Ranger have been placed in our nice new insulated foam box, complete with packing peanuts, in the corner between the x and y arms. The Guralp breakout box has been reinstalled and everything is plugged in in prepartion for the huddle test. However, we're having some issues with ADC channels, which will be worked out tomorrow (hopefully) so that data can be collected over the weekend.
Currently, one Guralp is plugged into the three SEIS-MC1 channels. We made new channels for the second Guralp (GUR-EW, GUR-NS, and GUR-VERT), but had issues with those. So, EW and NS have been plugged into PEM_AUDIO-MIC1 and MIC2 for the time being.
I found that several of the cables are unlabeled so I'm not sure what's plugged in. In the end, I found that the TEMP_2, _3, & _44 channels were working and so I plugged in anything that looked seismic into there.
TEMP_2 is now apparently the X channel of the 2nd Guralp. If someone can figure out which cable belongs to the Y channel, please plug it into TEMP_3 and then we can fix the channel names.
I also removed (gently) all of the accelerometers from MC2's chamber. This didn't break the lock, but I intentionally broke it to make sure it reacquired fine. It did and the MC TRANS QPD showed no significant shift afterwards.
Friday, we were seeing a 2 Hz harmonic series in all of the PEM channels. Today I found that some bad person had put in a 4V (!) signal into one of the channels with a signal generator. The generator was also sneakily stuck way back inside the DCU rack. NO SECRET SIGNAL INJECTIONS!
Since the ADC has a 2Vpk range, this was saturating and putting in harmonics in all the adjacent channels. I disconnected it and turned off the function generator.
This is very nice. We have, for the first time, a real time plant with which we can test our changes of the control system. From my understanding, we have a control system with the usual POS/PIT/YAW matrices and filter banks. The outputs go to a separate real-time system which is running something similar and where we have loaded the pendulum TF as a filter. Cross-couplings, AA & AI filters, and saturations to come later.
The attached plot is just the same as what Peter posted earlier, but with more resolution. I drove at the input to the SUSPOS filter bank and measured the open loop with the loop closed. The loop wants an overall gain of -0.003 or so to be stable.
The offending beam dump has been removed, and the PMC relocked.
The second set of Guralp channels is now plugged into the PEM ADCU, into channels which are confirmed to be working. (Method: 1Vpp sine wave into channel, check with DataViewer).
Direction, Channel Name, .ini chnum, BNC plug # on ADCU
Vertical: C1:PEM-SEIS_GUR_VERT, 15023, #24
N/S (should be Y when the seismometer is put in place): C1:PEM-TEMP_2, 15001, #2
E/W (should be X when the seismometer is put in place): C1:PEM-TEMP_3, 15002, #3
There is IFO work going on, so I don't want to rename the channels / restart fb40m until a little later, so I'll just use the old TEMP channel names for now.
There is something totally wrong with the E/W channel. I can look at all 3 channels on a 'scope (while it's on battery, so the op-amps in the breakout box aren't grounded), and VERT and NS look fine, and when I jump around ("seismic testing"), they show spikes. But the EW channel's signal on the 'scope is way smaller, and it doesn't show anything when I jump.
I might use the handheld Guralp tester breakout box to check the seismometer. Also, a suspicion I have is that whoever put the box back in on Friday night after our final noise measurements left the inputs shorted for this one channel. It's the 3rd channel in the set, so it would be most likely to be stuck shorted... Investigations will ensue.
Maybe it was Russell Crowe
I aligned the MZ. The reflection went from .86 to .374
I've added the PIT and YAW dofs to the MDC and MDP systems. The pendula frequencies in MDP are 0.8, 0.5, 0.6 Hz for POS, PIT, and YAW respectively. The three dofs are linear and uncoupled, and stable, but there is no modeled noise in the system (yet) and some gains may need bumping up in the presence of noise. The MDC filters are identical for each dof (3:0.0 and Cheby). The PIT and YAW transfer functions look pretty much like the one Rana recently took of POS, but of course with the different pendulum frequencies. I've attached one for YAW.
We discussed a preliminary game plan for this project. The thing I really want to see is an ETMX RCG controller hooked into the existing frontend via reflective memory, and the 40 m behaving normally with this hybrid system, and my list is geared toward this. I suspect the list may cause controversy.
+ copy the MDC filters into SAM, and make sure everything looks good there with DTT and SR785.
+ get interface / wiring boards from Wilson House, to go between megatron and the analog ETMX system
+ test tying the ETMX pendulum and bare-bones SAM together (use existing watchdogs, and "bare-bones" needs defining)
+ work some reflective memory magic and create the hybrid frontend
In parallel with the above, the following should also happen:
+ MEDM screen design
+ add non-linear bits to the ETMX MDP/MDC model system
+ make game plan for the rest of the RCG frontend
All the channels are now good, and all the names are back to making sense.
The problem with EW2 was in fact that the alligator clip used to short the inputs during the noise test Friday night was left in the box. Not great, but now it's taken care of, and we have recorded data of the noise of the breakout box, so we can include that in our plots to see if we're at the limit of how good we can do at subtracting noise.
The channels are now named thusly:
C1:PEM-SEIS_GUR_VERT (BNC input #24, .ini channel #15023)
C1:PEM-SEIS_GUR_EW (BNC input #3, .ini channel #15002)
C1:PEM-SEIS_GUR_NS (BNC input #2, .ini channel #15001)
C1:PEM-SEIS_MC1_X (BNC input #11, .ini channel #15010)
C1:PEM-SEIS_MC1_Y (BNC input #12, .ini channel #15011)
C1:PEM-SEIS_MC1_Z (BNC input #10, .ini channel #15009)
C1:PEM-SEIS_MC2_Y (Ranger, which for the Huddle Test is oriented VERTICALLY) (BNC input #4, .ini channel #15003)
Now we wait.....and tomorrow extract the noise of each of the seismometers from this!
This afternoon we tried to improve the mode matching of the beam to the PMC. To do that we tuned the positions of the two lenses on the PSL table that come before the PMC.
We moved the first lens back an forth the without noticing any improvement on the PMC transmitted and reflected power. Then we moved the first backwards by about one cm (the order is set according to how the beam propagates). That made the things worse so we moved also the second lens in the same direction so that the distance in between the two didn't change significantly. After that, and some more adjustments on the steering mirrors all we could gain was about 0.2V on the PMC transmission.
We suspect that after the problems with the laser chiller of two months ago, the beam size changed and so the mode matching optics is not adequate anymore.
We have to replace the mode matching lenses with other ones.
the servo needs some work.
2 day trend
While writing my progress report, I redrew the Guralp breakout box circuit diagram with all the changes marked. Since only one hard copy exists, I thought it might be useful to post my drawing up in case it is needed for any reason. The two drawings are the same - the second has just been broken into two parts to make it easier to fit on a normal 8.5 x 11 or A4 sheet of paper. The gains for each opamp have not been marked, but they could very easily be added in if necessary. The black resistances and capacitances are the originals. All changes have been indicated in blue.
I was able to observe the three sets of modulation sidebands created by the EOM + triply resonant circuit yesterday. Quantitative results will be posted later.
Spent a lot of time aligning tonight. The BS is not staying put--sometimes after a lock loss it gets badly mis-aligned.
DD handoff is working, after putting beam on REFL diodes and running senseDRM script.
I measured the magnitude of modulation as a function of frequency using the optical spectrum analyzer and an oscilloscope while generating signals using a Marconi signal generator; the results are shown in the attached plot and are compared to the expected modulation given the measured transfer function of the circuit and the nominal modulation index of the EOM used (13 mrad/V). Using the oscilloscope, I found the resonant peaks to be at 11.11 MHz, 29.57 MHz, and 54.70 MHz. There are several different colors on the plot; this is because I had to take the data in several different segments and had to switch to measuring a different sideband partway through the measurment. I also separately found the modulation at each resonant peak for each sideband. The magnitude of modulation was measured by finding the ratio between the magnitude of the carrier and sideband powers using an oscilloscope, and calculating the magnitude of modulation from this. This method was also used to quantify the dependence of modulation magnitude on input power at each resonant peak; these results are also attached. These same results can also be plotted as modulation magnitude as a function of voltage into the resonant circuit; this is also attached (I'm not sure which is more useful).
In order to produce these results (get the measurements in mrad/V) it was necessary to measure the gain of the amplifier. I used the signal generator to input signals of varying power and measured the output signal voltage using the oscilloscope; I then repeated this process at each resonant frequency. From this I was able to calculate the gain of the amplifier to be 28.1 dB at 11.11 MHz, 27.4 dB at 29.57 MHz, and 25.7 dB at 54.70 MHz. These values are in the same ballpark as the values in the Mini Circuits data sheet (all values are ~25-28 MHz).
Today I set up the EUCLID long range michelson design on the SP table; It's the same as the setup posted earlier, but without the pickoff (at PD1), which can be added later, and a few other minor changes (moved lenses, mirrors, PDs - nothing major). I hooked up the two PD's to the oscilliscope and got a readout that pointed to more power hitting PD2 than PD3.
So that I can collect a bit of free-swinging Mode Cleaner data, I started a script to wait 14400 seconds (4 hours), then unlock the mode cleaner. It should unlock the MC around 4am. As soon as someone gets in in the morning, you can relock it. I should have plenty of data by then.
When Rob and I were getting started on locking for the evening, Mode Cleaner lost lock a few times, but every time it lost lock, it took forever to reaquire, and was pretty insistent on locking in the TEM10 mode. I proposed that the alignment might be sketchy. I've been fiddling with the MC alignment sliders for the last hour and a half or so, but I think I'm not 100% in tune with the 3 mirror parameter space. The mode cleaner now locks, but I'm not in love with its' alignment. The WFS are definitely catywhompus. Before doing hardware things like recentering the WFS, I'm going to wait until tomorrow to consult with an alignment expert.
In case this is helpful for tomorrow, before I touched any of the sliders:
Optic, Pitch, Yaw
MC1, 3.1459, -0.7200
MC3, -0.8168, -3.0700
MC2, 3.6360, -1.0576
Now that mode cleaner locks, although not in a great alignment:
MC1, 3.1089, -0.7320
MC3, -0.7508, -3.0770
MC2, 3.6610, -1.0786
If I knew how to kill my script to unlock the mode cleaner, I would. But I sourced it, and Rob didn't know earlier this evening how to kill something which is started with 'source' since it doesn't seem to get a process number like when you './' to run a script. So the Mode Cleaner will probably be unlocked in the morning, and it may be persnickity to get it relocked, especially if the tree people are doing tree things with giant trucks again in the morning.
Rana, Jan, Jenne
We noticed that the Ranger data was all bogus at low frequencies. So we checked it and found that the proper procedure had not been used when changing it from horizontal to vertical last week. So the huddle test data from the weekend is not valid for the ranger; we will have to repeat it sometime.
So we used the manual, and extended the hanger rod on top of the Ranger to free the mass. It now has good response and coherence with the Guralps down to 0.1 Hz. See attached plot soon.
I put all three seismometers and all six accelerometers together in the foam box with peanuts. Three of the accelerometers are facing in the x-direction and three are in the y-direction. Both Guralps are aligned on the NS axis and the Ranger is pointing vertically.
**EDIT: The accelerometers are in the x and z directions, not x and y. Sorry, I was sleepy when I wrote this.**
One of the accelerometers was refusing to show anything, and after a few hours of checking connections and swapping cables, I discovered that someone had unplugged the cable from the ADC. A quick glance in the dataviewer shows that the channel has been unplugged since about 3 in the afternoon on August 8th (Saturday). So... obviously all the accelerometer measurements made with that channel since then did not actually get recorded. Yay.
Anyway, as of 2:45, everything is working and taking data. Clearly we're not getting a full night's worth... hopefully that's okay.