Sorrensen ps ouput of +15V at rack 1X9 was current limited to 10.3V @ 2A
Increased threshold to 2.1A and the voltage is up to 14.7V
Our fluorecent lights became obsolete. We'll have change fixtures over to some more energy efficient one. Do you have any recommendation regarding to less noise performer unit?
We may go this direction of LED fluorecent lamps ?
For the RF PD Frequency Response Measurement project, we get each PD signal from the "PD RF Mon" output of each demodulator board corresponding to our PD under test. Therefore we can't neglect the frequency response of various filters inside the demodulator board. I used our Agilent 4395 Network Analyzer to gather frequency response data for each demodulator board being considered for the RFPD frequency response project (AS55, REFL11, REFL33, REFL55, REFL165, POX11, POP22, POP110).
The NA swept over a frequency range of 1-500 MHz. Data was collected using NWAG4395A (from the netgpibdata directory). It should be noted that the command line options -a 16 -x 15 (averaging=16 and excitation amplitude=15 dBm[the max]), in addition to the usual command line options described in the help file, were used to minimize noise.
The data is located in /users/alex.cole. The file names are in the format [PDNAME]DemodFilt_1000000.dat (e.g. REFL11DemodFilt_1000000.dat). Results for POP110 are shown below.
This post pertains to the fiber-coupled diode laser mounted in rack 1Y1.
To turn the laser on, first turn the power supply's key (red) to the clockwise. Then make sure that the laser is in "current" mode by checking that the LED next to "I" in the "Laser Mode" box in lit up. If the light is not on, press the button to the right of the "I" light until it is. Now press the output button (green). This is like removing the safety for the laser. Then turn the dial (blue) until you have your desired current. Presently, the current limit is set to around 92 mA.
To turn the laser off, dial the current back down to 0mA and turn the key (red) counterclockwise.
I routed cables (RG405 SMA-SMA) from several demodulator boards in rack 1Y2 to the RF Switch in rack 1Y1 using the overhead track. Our switch chassis contains two 8x1 switches. The COM of the "right" switch goes to channel 7 of the "left" switch to effectively form a 16x1 switch. The following is a table of correspondences between PD and RF Switch input.
ThePOP110 demod board has not yet had a cable routed from it to the switch because I ran out of RG405.
We should also consider how important it is to include MCREFL in our setup. Doing so would require fabrication of a ~70 ft RG405 cable.
c1x01 timing issue was solved. Now all of the models on c1iscex are nicely running.
- c1x01 was synchronized to 1PPS in stead of TDS
- C1:DAQ-DC0_C1X01_STATUS (Upper right indicator) was red. The bits were 0x4000 or 0x2bad.
C1:DAQ-DC0_C1X01_CRC_SUM kept increasing
- c1scx, c1spx, c1asx could not get started.
- login to c1iscex "ssh c1iscex"
- Run "sudo shutdown -h now"
sudo shutdown -h now
- Walk down to the x end rack
- Make sure the supply voltages for the electronics are correct (See Steve's entry)
- Make sure the machine is already shutdown.
- Unplug two AC power supply of the machine.
- Turn off the front panel switch of the IO chassis
- Wait for 10sec
- Turn on the IO chassis
- Plug the AC power supply cables to the machine
- Push the power switch of the realtime machine
I aligned both the X and Y end green to the arms.
New AG4395, sn MY41101114 for West Bridge Labs was delivered. For the test purpose it is at the 40m now.
I made a series of tests in order to find anything broken.
Network analyzer test
- RF out / Rch test
RF out directly connected to R input channel.
The received power at the R-ch was measured while the output was swept from 10Hz to 500MHz.
The RF power was changed from -50dBm to +15dBm with +10dBm increment (but the last one).
The attenuator setting was changed from 50dB to 0dB.
=> The configured output power was properly detected by the R channel.
=> RF output is producing the signal properly. R-ch is detecting the produced signal properly.
- Ach/Bch test
Same test as above for Ach and Bch
=> Same result as above
=> A-ch and B-ch are detecting the produced signal properly.
- Transfer function test
Connect a power splitter to the RF out. Detect the split signals by R-ch and A-ch
=> Measurement is at around 0dB +/- 1dB up to 500MHz.
Same measurement for B-ch
=> Same result
=> A/R and B/R indicates proper transfer function measurements.
RF out was split in to two. One was connected to R-ch. The other was connected to A-ch.
The thru response calibration was run.
=> The thru calibration was performed properly.
- Practical tranfer function measurements.
In the above calibration setup, various RF filters were inserted in the Ach path.
The measured data was extracted via GPIB connection.
=> Practical transfer function measurements were performed.
=> GPIB connectivity was confirmed
External reference test
- External 10MHz reference from an SRS frequency counter was connected to Ext Ref In
=> Ext Ref indicator on the screen appeard
=> The internal oscillator seemed to be locked to the external reference in
Spectrum analyzer test
- Measured the signals from DS345 by R/A/B ch
Sinusoidal signal (1V) swept from 10MHz to 30Mhz
=> Corresponding moving peak was detected in each case
- Noise level measurement
R/A/B channels were terminated. The attenuation at each port was set to 0dB.
Frequency span was changed between 500MHz, 10MHz, 100kHz, 1kHz.
=> Noise level of ~10nV/rtHz between 0.1-500MHz was confirmed. All R/A/B channels have the same performance.
As a part of the network analyzer test in the previous entry, the transfer functions of Mini-Circuits filters we have at the 40m were measured.
<<List of the filters>>
- LPF (SMA): SLP1.9, SLP5, SLP21.4, SLP30, SLP50, SLP100, SLP150, SLP750
- LPF (BNC): BLP1.9, BLP2_5, BLP5, BLP30
- BPF (SMA): SBP10.7, SBP21.4, SBP70
- HPF (SMA): SHP25, SHP100, SHP150, SHP200, SHP500
Since the RFM-Dolphin bridges for the ASX model was added to the c1rfm model, c1rfm kept timing-out from the single sample time of 60us.
The model had 19 dolphin accesses, 21 RFM accesses, and 9 shared memory (SHM) accesses.
At the beginning 2 RFM and 2 SHM accesses were moved to c1sus (i.e. they were mistakenly placed on c1rfm).
But this actually made the c1sus model timed out. So the model was reverted.
The current configuration is that the WFS related bridges were accommdated in the c1mcs model.
This made the timing of c1rfm ~40us. So it is safe now.
On the other hand, the c1mcs model has the time consumption of ~59us. This is marginal now.
We need to understand why any RFM access takes such huge delay.
Eric and Steve,
We removed Wilcoxon Accelerometer PS and Amplifier unit under the BS optical tabel yesterday. The six cabels going to DAQ were labeled and left in place. Gain setting were 100, except channel 3 was 10.
The ~ 40 m long 2 sets of 3 cables were very happy to get their kinks out. Especially the set going just south of ITMX optical table.
We have to take better care of these cables! Your data will be useless this way.
[Koji, Nic, Manasa]
Update from last night.
Koji and I realigned the green optics on the PSL to start working on the ALS.
We set on a beat note search. We couldn't find the beat note between any of the arm green transmission and the PSL green. All we could see was the beat between the X arm and the Y arm green leakage.
Since we had the beatnote between the 2 green transmission beams, we decided to scan the PSl temperature. We scanned the SLOW actuator adjust of PSL; but couldn't locate any beat note. The search will continue again today.
Beat notes were recovered for both the arms.
I locked the arms to IR using PDH and measured the ALS out of loop noise at the phase tracker output.
The Y arm has the same 300Hz/rtHz rms. The X arm rms noise measures nearly the same as the Y arm in the 5-500Hz region (X arm has improved nearly 10 times after the last whitening filter stage change old elog ).
The noise in the ALSX error signals could be related to the bad alignment and conditions at the X end.
After many, many moons of getting to know exactly how frustrating Altium can be, I have completed the PCB layout for my ISS board (final page of ISS_v3.pdf).
Before I get into detail about the PCB, there is one significant schematic change to note: the comparator circuit was changed (with significant help from Koji) so that the voltage reference for boost triggering is established in a more logical way. Instead of the somewhat convoluted topology I had before, now there are only two feedback resistors, R82 and R83. Because their resistances (500k and 50k respectively) are so much larger than the total resistance of the 1k potentiometer (used to establish a tunable threshold voltage), the current flowing through the feedback loop is negligible compared to the 5 mA current flowing through the potentiometer (the pot is rated for 2 W and with 5 mA -> 25 mW dissapation). This allows one to set the threshold voltage for my schmitt trigger, at pin 2 of both the pot and the comparator, entirely with the pot. This trigger also has hysteresis given by the relation deltaV ~ (R83/R82) * (Voh - Vol) where deltaV is the separation between threshold voltages, Voh is the high-level comparator ouput and Vol is the low-level comparator output. Koji simulated this using CircuitLab and I plan to verify the behavior by making a quick prototype circuit.
Now, on to the PCB. The board itself is of a 'standard' LIGO size (11" x 6") has 3 routing layers and 3 internal planes, one for +15 V, one for -15 V and one for GND. In the attached pdf, red is the top routing layer, blue is the bottom layer and brown is the middle routing layer (used for ±5 V exclusively). The grey circles are pads and vias (drilled through) and anything in black is silkscreen overlay. I placed each component and track by hand, attempting to minimize the signal path and following the general rules below,
Sections of the board have been partitioned and labeled with silkscreen overlay to help in both signal pathway recognition as well as eventual troubleshooting.
On the board, I have also included holes so that it can be mounted inside of an enclosure. There is a DCC number printed as well as a 'barcode' (TrueType font: IDAutomationC39S), although they both contain filler asterisks as I haven't published this to the DCC and thus do not have a number.
Apparently all of the ION pump valves (VIPEE, VIPEV, VIPSV, VIPSE) opened, which vented the main volume up to 62 mTorr. All of the annulus valves (VAVSE, VAVSV, VAVBS, VAVEV, VAVEE) also appeared to be open. One of the roughing pumps was also turned on. Other stuff we didn't notice? Bad.
Several of the suspensions were kicked pretty hard (600+ mV on some sensors) as a result of this quick vent wind. All of the suspensions are damped now, so it doesn't look like we suffered any damage to suspensions.
CLOSE CALL on the vacuum system:
Jamie and I disabled V1, VM2 and VM3 gate valves by disconnecting their 120V solenoid actuator before the swap of the VME crate.
The vacuum controller unexpectedly lost control over the swap as Jamie described it. We were lucky not to do any damage! The ion pumps were cold and clean. We have not used them for years so their outgassing possibly accumulated to reach ~10-50 Torr
I disconnected_ immobilized and labelled the following 6 valves: the 4 large ion pump gate valves and VC1, VC2 of the cryo pump. Note: the valves on the cryo pump stayed closed. It is crucial that a warm cry pump is kept closed!
This will not allow the same thing to happen again and protect the IFO from warm cryo contamination.
The down side of this that the computer can not identify vacuum states any longer.
This vacuum system badly needs an upgrade. I will make a list.
While I was doing the oil change of the roughing pumps I accidentally touched the 24 V adjustment knob on the power supply.
All valve closed to default condition. I realized that the current indicator was red at 0.2A and the voltage fluctuated from 3-13V
Increased current limiter to 0.4A and set voltage to 24V I think this was the reason for the caos of valve switching during the VME swap.
Based on the facts above I reconnected VC1 and VC2 valves. State recognition is working. Ion pumps are turned off and their gate valves are disabled.
We learned that even with closed off gate valves while at atmosphere ion pumps outgass hydrocarbons at 1e-6 Torr level. We have not used them for this reason in the passed 9 rears.
I need help with implementing V1 interlock triggered by Maglev failure signal and-or P2 pressure.
MEDM screen agrees with vacuum rack signs.
Yesterday we cleaned up the ASX model and screens to have more straight forward structure of the screen
and the channel names, and to correct mistakes in the model/screens.
The true motivation is that I suspect the excess LF noise of the X arm ALS can be caused by misalignment
and beam jitter coupling to the intensity noise of the beat. I wanted to see how the noise is affected by the alignment.
Currently X-end green is highly misaligned in pitch.
- Any string "XEND" was replaced by "XARM", as many components in the system is not localized at the end table.
- The name like "XARM-ITMX" was changed to "XARM-ITM". This makes easier to create the corresponding model for the other arm.
- There was some inconsistency between the MEDM screens and the ASX model. This was fixed.
- A template StripTool screen was created. It is currently saved in users/koji/template as ASX.stp.
It will be moved to the script directory once it's usefulness is confirmed.
The next step is to go to the end table and manually adjust M2 mirror while M1 is controlled by the ASX.
The test mass dithering provides the error signal for this adjustment but the range of the PZT is not enough
to make the input spot position to be controlled. In the end, we need different kind of matching optics
in order to control the spot position. (But is that what we want? That makes any PZT drift significantly moves the beam.)
Rana and I connected the PMC_trans output to the BNC connector board on the west end of the PSL table (the channel is labeled). I took a few spectra off of PMC_trans and the SR785 was connected directly to the PMC_trans output for about an hour.
Data will follow.
I took the "aso-laptop" and made it into Ubuntu a couple months ago. Today I added it to the Martian network and then moved it to the X End.
I followed the instructions in (https://wiki-40m.ligo.caltech.edu/Network) and added it to the files in /var/named/chroot/var/named on linux1 and did the "service named restart".
The router already had his MAC address in its list (because Yoichi was illegally using his personal laptop on the Martian). The new laptop's name is 'asia'. This is a legal name according to our computer naming conventions and this Wikipedia page (http://en.wiktionary.org/wiki/Category:Italian_female_given_names). It has been added to the Name Pool on the wiki.
The terminal on the laptop still calls itself 'aso-laptop' so I need some help in fixing that. It successfully connects to 40MARS and displays a MEDM sitemap after sshing in to pianosa.
I use 'ssh -X -C' since I find that compression actually helps when the laptops are so far from the router.
Sun Aug 18 15:52:50 2013
Found the FB lights (C1:FEC-NN_FB_NET_STATUS and C1:DAQ-DC0_C1XXX_STATUS) RED for everything on the CDS_FE_STATUS screen.
I used the (! mxstream restart) button ro restart the mxstreams. Everything is green now.
PMC was out of lock- relocked it and the IMC locked itself as did the X & Y arms on IR. X was already green locked.
I noticed at LLO (?) that the LSC screen there uses up ~25-30% of the CPU time on a single core for the control room iMac workstations - this seems excessive.
Here is an accounting of CPU usage percentages for some of our screens:
These were measured using the program 'glances' on rosalba. MEDM running with only the sitemap used up 0.9% of a CPU. With the screens running, the fluctuation from sample to sample could be ~ +/- 0.5%. While the LSC screen seems to be the biggest pig, it is only big in comparison to small pigs. Certainly this pig has gotten bigger after getting sent to Louisiana.
JoeB and JamieR are working somewhat coherently on a set of python libraries to fulfill all of our command line CDS wants. This is being done mostly to satisfy The Guardian and the SkunkTools project.
I did an 'svn up' in /opt/rtcds/userapps (it might finish in ~1000 years) to get the things that they have so far (in particular, Joe's 'pyavg'). There's going to be some issues since the pylib stuff written by Yuta/Kiwamu has never been integrated with anything and is imported as 'epics' in many python scripts. As we move over to the new stuff there will be a lot of broken script functions since the new libraries are also used in that way.
ETMX sus damping restored
This is an elog about the activity on Friday night.
- The X arm green beam was aligned with assist of the ASX system.
- M1 PZT alignment was swept while M2 PZT was under the control of ASX.
- Everytime M1 was touched, M2 was restored by manual alignment so that the REFL beam hits the center of the REFL PD.
This way we could recover the lock of TEM00. Once TEM00 is recovered, ASX took care of the alignment of M2
- The error signal used by the cavity dither did not give us a good indication where the optimal alignment is.
- Thus the best alignment of M1 had to be manually scanned. The resulting maximum green transmission was ~0.88
- Once the beam was aligned, the out-of-loop stability of the Xarm was measured.
There has been no indication of the improvement compared to Manasa's measurement taken before our beam alignment.
Masayuki Nakano, a student of Seiji's from ICRR / U Tokyo, is visiting us here at the 40m lab for the next couple months.
He received 40m specific basic safety training this morning.
We can not leave cables connected like this. This is a burned toast award.
When I came in this morning, I noticed that the Mode Cleaner had not been locked for at least the past 8 hours. We moved the MC SUS sliders until the MC SUSPIT and SUSYAW values for each mirror were back to approximately the place they were the last time the MC was nicely locked (~12 hours ago). This got the MC flashing TEM00, so we thought we were doing well.
However, if the servo was enabled, any time the cavity flashed a small-order mode (especially 00), the mirrors would get super kicked. Not good.
We went to investigate, and discovered that the RFPD aux laser was left on again. We turned that off, however that didn't fix the situation.
Manasa suggested checking that the WFS were really, really off. When we looked at the WFS master screen, we noticed that although the WFS servos were off, the MC mirrors' ASC filter banks had non-zero inputs. We checked, and this is not from the MCASS, nor is it from the MC WFS lockins. At this point, I have no idea where these signals are coming from. I have turned off the ASC outputs for all the MC mirrors (which means that we cannot turn on the WFS), and the MC locks fine.
So, we need to know where the ASC signals are coming from. There isn't anything that I can see, from any screen that I can find, that indicates some signals being sent over there. Has anyone done anything lately? I know Koji was working on IPC stuff the other day, but the MC was locking fine over the weekend until yesterday afternoon, so I suspect that's not the culprit.
I have turned off the outputs of the WFS lockins, as part of my turning things off, so if whatever script needs them doesn't enable them, they should be turned back on by hand.
This disturbance in the MC ASC channels were fixed.
This craziness happened ~10pm last night. Was there any action at the time? >> Sunday-night workers? (RXA: No, Nakano-kun and I left before 9:30 PM)
We found that the signals came from c1ioo. However, restarting, recompiling c1ioo and c1mcs didn't help
to clean up this issue. Just in case we cleaned up the corresponding entries in the ipc file /opt/rtcds/caltech/c1/chans/ipc/C1.ipc
and recomplied c1ioo and c1mcs because these are the channels we touched last week to mitigate the timing out issue of c1rfm.
Incidentally, we fell into a strange mode of the RCG: IOPs could not restart. We ended up running "sudo shutdown -r now"
on each machine (except for c1lsc which was not affected by this issue). This solved the issue.
Even now c1oaf could not be running properly. This is not affecting the IFO operation right now, but we need to look into this issue again
in order to utilize OAF.
ASX scripts for PZT dither have been fixed appropriately. Script resides in scripts/ASX.
You can run the scripts from the ASX medm screen now.
Shutter moved, no more clipping.
Pick-off mirror 2" replaced by 1" one. Laseroptik HR 532nm, incident angle 30-45 degrees, AR 532 nm
Green REFL PD moved to 4" close to pick-off mirror. Pd being close to pick-off does not separate multiple reflections on it. I'll replace Laseroptic mirror with Al one. It is not easy to find.
Hole cut into side wall for doubler oven cable to exit.
- An Aluminum mirror instead of 2" unknown mirror for the pick-off for the rejected beam from the green faraday isolator (Steve)
=> Replaced. To be reviewed
- Faraday mount replacement. Check what we have for the replacement. (Steve)
- The green REFL PD should be closer to the pick-off mirror. (Steve)
=> Moved. To be reviewed
- A beam dump should be placed for the green REFL PD
- Move the green shutter to the place where the spot is small (Steve)
=> Moved. To be reviewed.
- The pole of the PZT mounting should be replaced with a reasonable one. (Steve with Manasa's supervision)
- Tidying up doubling oven cable. Make a hole on the wall. (Steve)
=> Done. To be reviewed.
- Tidying up the PZT cabling (Steve)
- The optics are dirty. To be drag wiped. (Manasa, Masayuki)
Here are a bunch of sensing signals. The configuration is always DRMI. Except for the optic noted in the title and the x-axis of any individual plot, other optics are held in their nominal position. DRMI condition is sidebands resonant in PRCL, 55MHz sideband resonant in SRCL. Each plot has an error signal, as well as the 2f signals at POP and AS.
The phases of POP22 and POP110 have been adjusted so that the I signal is maximized when everything is at the nominal positions (sideband resonant for PRMI). The phase of AS110 has been adjusted so that the I signal is maximized when the DRMI is in the nominal position (f2 resonant in SRC). The phases of the 1f1, 1f2, 2f1 and 2f2 REFL signals were all adjusted to have max PRCL signal in the I phase. AS55 was adjusted to have max SRCL signal in the Q phase.
While Jenne was plotting, I locked and aligned the MICH with AS55_Q. Then I aligned the PRM and locked PRMI using REFL55_I/Q with triggering on POP22, but no power normalization.
I used this to set the phase for REFL11 and REFL55 (driving PRM at 111.3 Hz and minimizing the Q response using the DTT Sine Response tool). I flipped the sign on REFL11 by
The REFL11 gain is ~50x larger than REFL55; this is with the 15 dB whitening gain on REFL55 and none for REFL11. What's going on here? The attached PDF shows the two time series with the free swinging PRMI and both phases set to ~ +/- 2 deg. The REFL55 signals have been scaled up by 50x.
So then we went in and looked at the RF signals at the demod boards. To do this we disconnected the RFPD test cables and hooked the RF Mon outputs into the 50 Ohm inputs on a scope. The following PNG images show the scope traces. The REFL11 (yellow) traces are too big!! See how small the REFL55 (green) are. REFL11 is saturating - need to fix.
According to the wiki, REFL 11 has a transimpedance of 4.08kV/A, and REFL 55 has a transimpedance of 615V/A. This is a ratio of ~6.5 . My optickle simulations from earlier this evening indicate that, at maximum, there is a ~factor of 2 more signal in REFL 11 than REFL 55. This is a factor of order 10-15. Then, REFL 55 has 15dB whitening gain, which is a factor of ~4. So, this explains why we're seeing so much more digital signal on REFL11 than REFL55.
Tomorrow, I need to replace the 50/50 beam splitter that splits the beam between REFL55 and REFL11 (33 and 165 have already had their light picked off at this point). I want to put in a 10% reflector, 90% transmission beamsplitter. Steve, can you please find me one of these, and if we don't have one, order one? This will give us a little more light on 55, and less light on 11, so hopefully we won't be saturating things anymore.
Beam trap for Pd refl is in place. Cabeling is ti·died up.
Laseroptic 1" mirror is replaced by Al 1" mirror. Problem remains the same. This diffraction patter has to be coming from the Faraday.
Atm1, good separation when Pd is far
Atm2, bad separation when Pd is close
As I always tell everyone: Don't use a 10% reflector which produce ghost beams. Use a 90% reflector.
As I always tell everyone: Don't use a 10% reflector which produce ghost beams. Use a 90% reflector.
Hmmm, yes, I forgot (bad me). I'll find a 90% refl BS, and swap the positions of REFL11 and REFL55.
/home/cds is >98% full - below are some of the usage numbers:
controls@rosalba:/users/OLD 0$ du -h --max-depth=1
controls@rosalba:/opt/rtcds/userapps 0$ du -h --max-depth=1
linux1:cds>nice du -h --max-depth=1
du: `./llo/chans/daq/archive': Permission denied
du: `./llo/chans/daq/old': Permission denied
I have done the swap in the REFL path. First, I swapped the positions of REFL11 and REFL55. Then, I swapped out the 50/50 BS for a 90% reflection BS. (90% goes to REFL55, 10% goes to REFL11). I also changed the aluminum dump that was dumping the old REFL165 path into a razor dump.
Before: REFL11 had 4.0mW, REFL55 had 3.1mW. Now, REFL11 has 0.53mW, and REFL55 has 6.9mW. REFL165 still has around 61mW of light, and REFL33 has 3.3mW (the things that were changed were after 165 and 33 in the REFL path).
Now, the DC value of the REFL PDs are: REFL165 = 10.4V, REFL33 = 110mV, REFL55 = 232mV, REFL11 = 18.6mV.
As I was finishing aligning the beams onto all of the REFL diodes, Manasa asked for the IFO so she and Masayuki could continue their work on the Xarm, so I'll check the signals acquired a little later.
Today we measured the openloop transfer function of the PDH green lock of the x-arm.
Edit //manasa// The excitation was given from SR785 source. SR560 was used as the summing node at the PDH servo box output where the loop was broken to measure the OLTF. The SR785 was used to measure the frequency response (CH2/CH1; CH1 A SR560 output and CH2 A PDH servo output) in sweptsine mode.
We measured with two different servo gain. We started with the servo gain of 3 and at that gain the UGF was 1.5 kHz and the phase margin was 50 degree. After that we increase the servo gain to 5.5 and at that gain the UGF was 6.2 kHz and the phase margin was 55 degree. In all the measurement we use the source amplitude of 1.0 mV for all frequencies (from 100 Hz to 100 kHz). We could not increase the gain and also the source amplitude any more because the green was kicked out of lock.
Next work list
1. In the earlier measurements we found the UGF of the PDH green lock of the x-arm as 10 kHz and the phase margin as 45 degree, so we will investigate what has changed from these measurements.elog 4490
2. We will measure the power spectrum of the error signal and the feedback signal.
3. We will calibrate the above signals to compare with ALS out of loop noise.
netgpib was taking forever to transfer data. So the measurements are just photos of the display.
attachment1 - servo gain 3
attachment2 - servo gain 5.5
One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.
On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.
I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.
(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)
Yes, this was not ELOG'd by me, unfortunately. This was the MC tickler which I described to some people in the control room when I turned it on.
As Koji points out, with the MCL path turned off this injects frequency noise and pointing fluctuations into the MC. With the MCL path back on it would have very small effect. After the pumpdown we can turn it back on and have it disabled after lock is acquired. Unfortunately, our LOCKIN modules don't have a ramp available for the excitation and so this will produce some transients (or perhaps we can ezcastep it for now). Eventually, we will modify this CDS part so that we can ramp the sine wave.
I've written a new TICKLE script using the newly found 'cavget' and 'cavput' programs. They are in the standard epics distribution as extension binaries. They allow multichannel read/write as well as ramping, delays, incremental steps, etc. http://www.aps.anl.gov/epics/tech-talk/2012/msg01465.php.
Running from the command line, they seem to work fine, but I've left it OFF for now. I'll switch it into the MC autolocker at some point soon.
Today we measured OLTF of PDH green lock of x-arm again. In the previous measurement the excitation signal was injected at the PDH servo box output(elog 9044), but in this measurement we changed the injection point to the RFPD mixer output (just before the servo input).
We measured the OLTF with the servo gain of 6.5 and source amplitude of 5 mV for all frequency band. The measured UGF was 11 kHz and the phase margin was 48 degree.
Next that measurement, we tried to measure the power spectrum density of the error signal and feedback signal. But the alignment was not so good, so we aligned the green light injection point. Tomorrow we will continue the alignment and will measure the PSD.
attatchment1 - OLTF of PDH green lock with servo gain of 6.5
It seems that the PRM violin mode freqs shifted from 625-ish to 640Hz.
The peaks rang up because of the servo.
Once the notch freq was shifted to 640Hz, the violin mode started to decay.
The DRMI has been locked!! And at least one time, it was for more than one minute!!
We are not 100% sure yet that it's correctly sideband locked. The test of this was to put a 50% BS in front of the AS camera (so after the beam has gone to AS55), and send the light over to a PDA10CF Thorlabs PD. I locked the Michelson on carrier for the alignment of this diode. Then I strung a cable to the control room, and plugged it into the RF spectrum analyzer. (First, I had turned off the green beat PD power, so there wasn't any RF stuff on the line that I unplugged). It's hard to watch the screen and a tv / dataviewer at the same time, so I've taken a video, so that we can see the nicely locked round DRMI beam on the AS camera, and the spectrum analyzer. My phone is working very hard at uploading the video, but we may have to wait until tomorrow for that. However, I think that we're locked on the 55MHz sideband. (Also, maybe I'm too tired or excited or something, but how do you make the real cameras take video??)
EDIT: Video uploaded. Pause the video at 10 seconds, and you'll see that we've got a strong 110MHz peak!! Hoooray! The TV in the upper right side of the video is AS. You can see as we flash, the peaks go up and down. When there's no resonance, the 110 peak goes away. (Ex., when I'm PRMI locked on the sideband, there isn't a visible peak).
Alignment procedure was as normal: Lock and align the arms. Misalign ETMs. Check that MICH fringes look good (ASS does a nice enough job that I don't actually lock and align the Michelson anymore). Restore the PRM. Lock PRMI. Tweak PRM alignment to maximize POP110I. At this point, Koji and I played a little with the PRMI, but when we finished with that, we restored the SRM, and tweaked its alignment by making nice overlap on the AS camera.
Then, we tried some DRMI settings, started seeing some locks, and played a bit with trying to optmize the settings that we have.
PRCL ASC is on (with loop triggering). MICH gain = -0.8, PRCL gain = +0.05. FM4, FM5 always on, FM2 triggered. Loop and filter module triggering on POP22I. No power normalization. MICH and PRCL locked on REFL55 I&Q, with 1's in the LSC input matrix. PRCL actuating on PRM with +1, MICH actuating on BS with +0.5, PRM with -0.267.
I took transfer functions between REFL55 I&Q and REFL11 I&Q, to determine the relative gains and signs. REFL11I's gain should be -18dB relative to REFL55I, with the opposite sign. We tried PRMI locking with MICH = 1*REFL55Q and PRCL = -0.125*REFL11I for the input matrix. Still no power normalization (we haven't used power norm at all today, so I'll quit writing that).
I took transfer functions between REFL55 I&Q and REFL33 I&Q. REFL33I's gain is -8dB relative to REFL55I, but they have the same sign. We tried locking PRMI with MICH = 1*REFL55Q and PRCL = +0.6*REFL33I. Success.
Next up, some Optickle simulations, to help us go in the right direction for DRMI locking. I checked the signs of the error signals REFL55I (PRM sweep), REFL11I (PRM sweep) and REFL55Q (MICH sweep) in both PRMI and DRMI configurations. For all of these cases, the signs were the same (i.e. no sign flips needed to happen for DRMI locking, relative to PRMI locking). I checked the sensing matrices for DRMI and PRMI for those same signals, and took the ratios of the sensing matrix elements. This gave me the ratio of optical gains for each error signal, in the DRMI case vs. PRMI case, so any servo gain changes should be the inverse of these numbers. These numbers are all DRMI/PRMI: REFL55I PRCL response = 0.76, REFL11I PRCL response = 0.99, REFL55Q MICH response = 18. So, when trying to lock the DRMI, we wanted to keep the gains for PRCL about the same, reduce the servo gain for MICH by a factor of ~20, but keep the same signs for everything.
In doing that, we started seeing some short DRMI locks, so we twiddled some parameters (mostly the elements in the LSC input matrix) a bit. We eventually settled on: PRCL = -0.125*REFL11I, MICH = 0.1*REFL55Q, and SRCL = 1.0 * REFL55I. The output matrix was the same (MICH pushing on BS and PRM, PRCL on PRM), with the addition of a +1 in the SRCL -> SRM element. For all 3 degrees of freedom (PRCL, MICH, SRCL), FMs 4 and 5 were always on. For PRCL, FMs 2,3,6 were triggered to come on after 0.5 seconds of delay. The PRCL FM triggers helped enormously. I tried several other things, including changing the MICH input matrix element up and down in value, changing the SRCL input matrix element up and down in value, and engaging triggering for a few different filters in the MICH and SRCL degrees of freedom. However, none of these made things better, and several made things worse. Most notably, for SRCL, engaging triggering for FMs 2 and 3 kicked the cavities out of lock, which implies that perhaps our gain isn't high enough yet (and thus our UGF isn't very high yet). I changed FM1 of SRCL to be +3dB of gain (from +10dB), and it would live through that coming on (trigger delayed by 1 sec, then ramping up over 1 second), but within a second after the filter finishing coming on, the cavity would fall out of lock (not violently kicked, just not locked anymore).
At this point, we were trying to figure out a way to confirm what kind of lock we had. I checked Optickle again, and we do not expect to see a significant change in POP110I between the PRMI and DRMI cases, so that isn't a useful check. We dreamed of having our AS110 demod board, or the AS OSA set up, but neither of those was going to happen tonight. Instead, Koji suggested hooking up the PD, and looking directly at the output.
To-do: Set up the AS OSA. Also, perhaps temporarily borrow the 110 demod board from POP. We were triggering on POP22 tonight, and that seemed to work okay.
Very nice!! I was wondering, shouldn't the driving matrix be such that MICH pushes on SRM as well?
Wonderful ! I like the video -- the spatial mode looks pretty clean and much cleaner than what I observed in the old days.