Kiwamu and Dave.
Kiwamu made two restart of the h1suspr2 model, both required DAQ restarts to ingest the new INI files. The times of the DAQ restarts are
10:14 and 10:30 PST
[Ed, Evan]
We are preparing to make a measurement of the length of the PRC using the phase-locked auxiliary laser technique described by Chris Mueller (T1400047). Previously, this has been used to measure the Livingston IMC length (LLO alog 9599).
We set down a 520 mW Lightwave NPRO on the IOT2R table, along with a Faraday isolator and steering mirrors. We will inject this beam into the PRM_refl side of the IOT2R periscope. The beam will hit the back of IM4, and a small fraction (2400 ppm) will be transmitted toward the PRM. This gives 1.2 mW of auxiliary power on the PRM, compared to 9 mW of 45MHz PSL single-sideband power on the PRM.
Most of the auxiliary power should reflect from the back of IM4 and return to the IOT2R table via the IO_forward side of the periscope. For mode-matching, we hope that we can simply send part of the IO_forward beam onto a New Focus 1611 and maximize the observed beat. Currently, there is 3 mW of power in the IO_forward beam.
Using this beat, or otherwise, we will phase-lock the auxiliary laser to the PSL carrier beam. Then with PRMI locked on the PSL sideband, we will sweep the offset to the auxiliary PLL and monitor the RF coming out of POPAIR_B. We should see the strength of the RF reach a maximum whenever the auxiliary beam is coresonant with the the PSL sideband. By tracing out the Lorentzian profile of the RF amplitude across successive resonances of the PRC, we can extract the FSR of the PRC. Given a design length of 57.6557 m, we expect an FSR of 2 599 850 Hz. If we can measure the FSR to within 100 Hz, we can get the PRC length to within 2 mm.
Yesterday we got the NanoScan back from EX and Ed used it to measure the beam parameter coming out of the Faraday isolator. The waist is about 100 µm and located more or less in the middle of the isolator. The size is maybe a bit smaller than we want, but we appear to be able to get more than 90% of the power through, with a reasonably Gaussian mode.
After the FI, we placed a HWP to set the beam to be s-polarized. After this, we placed a New Focus 5104 as a first steering mirror. As a second steering mirror, we use IO_PRMR_BS1.
We removed a lens from between IO_PRMR_M3 and IO_PRMR_BS1. It was unlabeled, and anyway there is nothing after that lens except beamsplitters and dumps.
We did an ALM optimization to mode match to the PRM. Joe Gleason's IOT2R layout (D0902284) gives the distance from the bottom of the IOT2R periscope to the PRM as 3.6 m. The spot size is 2.24 mm, with a ROC of 11 m (T0900407, p 5). ALM told us to put an f = 500 mm lens about 3 inches before IO_PRMR_M3 ("before" meaning "closer to the FI").
We put down two irises in order to constrain the pointing of the PRM_Refl beam. We then blocked this beam and steered the auxiliary beam through the irises. With a little tweaking, we were able to see our beam coming out on the IO_Forward part of the periscope. We measured the power of this beam and found that it was only about 5% of what we were putting in. This initially confused us, until we realized that our path in HAM2 has to go through a 90% reflector which is intended for the ISS. Given that IO_PRMR_BS1 is a 90% reflector and ROM LH1 (in HAM2) is also a 90% reflector, we in fact only expect 90% × 90% × 10% = 8% of the power to come back onto the IOT2R table.
Yesterday, we put down the New Focus 1811, aligned the PSL and auxiliary beams from IO_forward onto the PD. We found a beat with the auxiliary laser temperature around 37.7 °C. By tweaking the auxiliary input pointing, we were able to get -4 dBm of RF beat out of the 1811 with about 1 mW of DC power from each beam in front of the PD (so 2 mW total).
We were then able to implement a PLL using an HP function generator and the LB1005 servo box. We set the function generator to ~30 MHz and +7 dBm, and used it to drive the LO of a mixer. We took the beat and put it into the mixer RF. The IF was terminated, filtered at 1.9 MHz, and then fed into the LB1005. The output of the LB1005 was then fed into the fast input of the laser. We were able to catch lock by turning the laser's temperature control knob to push the beat toward 30 MHz. The lock would hold for about 1 minute before the controller saturated. To maintain sanity, I suspect it will be necessary to implement a slow temperature loop to relieve the fast controller.
While pulling Dial Indicators at BSC9 yesterday I eyeballed the fluid catches and found the horizontal full and starting to drip. I cleaned up the catch and reinstalled. This hasn't been leaking as badly as the BS V2 had been but only no drips is tolerable. Changing this out will take HEPI down for a few hours--look for that next Tuesday.
HugoP reported on 12 Feb that we had an issue with the EndX HEPI being unable to tilt completely. We were requesting 390000nrads but only getting 350000. Hugo pushed it more and it went more but it would never go to the fuly requested value. Hint, hint--like there was an offset in the path...hummmm
I can't find an entry in the alog around Jan21, when this offset in the position request showed up (see Hugo's first link.) However, when I look a little deeper I find the offset was increase to 39000 on Friday Jan 17 by me to run the RY Tilt manually (I guess it shoould have been 390000.) It looks to me that on Monday the 21st, myself or Sebatian turned the HEPI position loops on but failed to turn off the offsets giving the offset observed since then. Obviously our 'greening' of the system must be more robust.
I found this yesterday after the RCG upgrade reboot attempting to get the system back on. The safe.snap was problematic so Dave reloaded form the 9am burt.
So by removing these offsets, the HEPI will now tilt that much more. If the alignment is intolerable, change the target/current setpoint on the DC BIAS medm from -389800 to -350000.
Pretty much as Fabrice directed and Shiela & Kiwamu report . One notable: The ITMX HEPI is off, not tripped. I think the safe.snap/burt restore process/setup for the SEI is troubled and needs attention. I guess that mainly means my job.
Unless someone tried to get the ITMX HEPI on and then left it in an unusual state, it came up screwy: Specifically--the Master switch is closed and the ISO gain is 1.0 but the Position Bias Screen is all zero. All the switches and filters are off on the IPSINF screen but the Switches are on and the filters are off on the L4CINF page. Etc etc...
This morning, Yuta complained that the alignment of PRY changed a lot and therefore he had to tweak either BS or ITMY by 60 urad or so --- of course, HEPIs and ISIs were tripped on ITMY and BS (see alog 10333).
After untripping them, we comfirmed that the alignment came back to where it should be without touching the suspension biases. The ISIs are currently in the damping mode.
They are now:
I found that ITMY had been tripped at the L1, L2 and L3 watchdogs. I untripped them. It is now in "aligned" state.
Arnaud, Sheila
We want to try the ETM drive diaonalization. One reason is that we can see that our longitudnal feedback to the top mass is causing pitch motion of the optic, and we will need the full drive diagonalization when we get the Y arm anyway, so we might as well do it now.
We had some disscussion about how to balance the coils when there are only 3 osems, in the end we decided to just do length 2 yaw, and then move on to measureing transfer functions. Tonight Arnaud and I had a first attempt at doing the length 2 yaw measurement, we just applied DC length offsets and used the OpLevs. This may need to be corrected if the OpLev calibration is revisited tomorow....
When we started there was a -0.004 in the length 2 yaw drivealign matrix, we could not tell from a search through the alog and talking to various people in the control room where this number came from, possibly it was copied over from ETMY. We have now replaced this with -0.0024.
Attached is a plot of our measurements and the script we used.
Daniel, Ed, Yuta, Stefan, After this morning's boot fest we noticed that the IMC reflected beam was completely misaligned, missing camera and WFS, and barley hitting the LSC diode. Interestingly, the IMC still locked with good build-up. We checked HPI, ISI and all involved SUSs for any drift. None showed any. Also, the PRX cavity still nicely locked. So we concluded that some mirror on IOT2L must have moved, and realigned that whole beam path. Everything worked fine again afterwards. In the process we also had accidentally moved an ASC POP picomoter (#6) horizontally (yaw). We were able go find the beam again, but once again confirmed that these picomotors are hugely asymmetric, i.e. the counters are only useful for suggesting an axis and direction.
Written by Yuta
This morning, I could dither PR2 and PRM from ASC-ADS, but I can't now.
For example, even if I put on H1:ASC-ADS_PRM_PIT_OSC, the signal doesn't show up at H1:SUS-PRM_M3_ISCINF_P_IN1.
Since it did this morning(6AMish~10AMish), I suspect this is related to the boot festival today.
If I lookup the simulink diagram, h1asc.mdl has H1:ASC_SUS_PRM_PIT_DITHER, but h1prm doesn't.
[PRMI dither alignent work this morning]
We want the alignment automation to speed up the PRMI commissioning.
I checked the guardian script for PRX dither alignment Evan and I made yesterday. It now works for PR2 dither alignment. PRX_ALIGN state closes PR2 (and PRM) dither alignment loop, wait for a while, and offloads the feedback offset (e.g. H1:SUS-PR2_M1_LOCK_P_OUT) to the alignment slider values (e.g. H1:SUS-PR2_M1_OPTICALIGN_P_OFFSET).
For PRM, I had to lower the excitation frequency for pitch/yaw from 14/11.5 Hz to 5.4/7.2 Hz, and excite not only M3 but also M2 to get the error signal. I haven't checked fully yet, but the guardian script should also work for PRM dither alignment.
Next work is to do BS(or ITMY) alignment using PRY.
Just to make it clear:
The excitation was not active because of a change in the ASC model rather than the SUS models. I was in the middle of splitting the ASC paths into the low frequency feedback and dither paths. Currently only PR2 is capable of having the split dither signal.
We have been experiencing issues with the BSC-ISI watchdogs since the models have been re-compiled this morning. They are not operating as they should. It may or may not be related to the rcg code update (it could also be due to some piece of SEI code that should not have been updated from the svn, for example). We have not found any obvious cause of the problem yet. The BSC-ISI units are currently working fine and safely in damping mode. As a measure of precaution, the master switches will be turned off at the end of the day.
ITMX and ETMX master switches are off
The cdsRampMuxMatrix part, which is new to RCG 2.8 (and updated in 2.8.3), allows for pre-writing a new matrix and then loading it with a specified ramp time from the current values to the new ones.
This part has been swaped into the PD_DOF_MTRX position in the main LSC library part in:
USERAPPS/lsc/common/models/lsc.mdl
The h1lsc model was rebuild/installed/restarted, and has been tested and seems to be working as expected.
The channel interface to the matrix has now changed. The readback channel retains the same form as the non-ramping matrix, but new channels are added to write the new matrix:
|
LSC-PD_DOF_MTRX_ |
current setting readback |
|
LSC-PD_DOF_MTRX_SETTING_ |
new setting value |
|
LSC-PD_DOF_MTRX_RAMPING_ |
indicator that element is ramping |
| LSC-PD_DOF_MTRX_TRAMP | ramp time |
| LSC-PD_DOF_MTRX_LOAD_MATRIX | load new values |
Scripts/guardian will need to be modified to write new matrix values accordingly.
The MEDM screens for the input matrix were updated with a new interface for the matrix. The updates screens are (screenshots below):
USERAPPS/lsc/common/medm/LSC_CUST_PD_DOF_MTRX_VAC.adl
USERAPPS/lsc/common/medm/LSC_CUST_PD_DOF_MTRX_AIR1F.adl
USERAPPS/lsc/common/medm/LSC_CUST_PD_DOF_MTRX_AIR2F.adl
USERAPPS/lsc/common/medm/LSC_CUST_PD_DOF_MTRX_CM.adl
Each matrix element is split vertically, with the readback of the current value at the top, and the new value at the bottom. The boxes are colored to indicate the state:
The "Kissel buttons" on the main LSC_OVERVIEW screen did not have to be modified since the readback channel did not change.
After much of the day was spent for recovery from maintenance, we wanted to make green WFS wider band, for which we need to redo penultimate mass to final mass pit to pit and yaw to yaw measurement, and since we're using OLs, and since OL whitening were bad but are now good, and since ISI is performing much better than the beginning of the HIFO_X, we decided to calibrate OL using baffle PDs again. And since we might want to use TMS for alignment we also did the calibration measurement for TMS.
We only had time for TMS and ITMX for today.
TMS:
Used H1:AOS-ITMX_BAFFLEPD_1_POWER and 3_POWER (3 is actually connected to PD4). Also recorded H1:SUS-ETMX_M0_DAMP_P_IN1 and H1:SUS-ETMX_M0_DAMP_Y_IN1 and used tdsavg.
"delta claimed" is the TMS rotation measured as the difference of bias offsets between PD4 and PD1, "delta physical" is derived from baffle diode drawing and the arm length of 4000m (see the drawing in this alog: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=9087).
Positive PIT means the beam points down. Positive YAW means the beam rotates counter-clockwise viewed from the top.
| ITMX baffle PD1 | ITMX baffle PD4 (channel name is PD3) | delta claimed | delta physical | correction factor | |
| TMS bias slider (P, Y) | (203.3, -228.1) | (272.7, -289.7) | (69.4, -61) | (71.8, -72.0) | (1.035, 1.180) |
| TMS BOSEMs | (286.46 470.24) | (396.13, 415.91) | (109.67, -54.33) | (71.8, -72.0) | (0.654, 1.325) |
| power on baffle PD (mW) | 0.22 | 0.24 |
ITMX:
Used H1:AOS-ETMX_BAFFLEPD_1_POWER and H1:AOS-ETMX_BAFFLEPD_4_POWER. Also recorded H1:SUS-ITMX_L3_OPLEV_PIT_OUT and H1:SUS-ITMX_L3_OPLEV_YAW_OUT.
"delta reality" is half the angle formed by PD4, ETM and PD1 as the beam rotates twice the angle of the ETM.
Positive PIT means that the optic points down. Positive YAW means the beam rotates counter-clockwise viewed from the top. OL has different sign convention from SUS for PIT here.
| ETMX baffle PD1 | ETMX baffle PD4 | delta claimed | delta reality | Correction factor | |
| ITM bias slider (P, Y) | (34.6, -74.9) | (66.9, -42.2) | (32.3, 32.7) | (37.34, 37.37) | (1.156, 1.143) |
| ITM OLs | (8.643, -3.20) | (-11.115, 14.845) | (-17.94, 16.34) | (37.34, 37.37) | (-2.081, 2.287) |
| ITM top BOSEMs | (246.65, -386.038) | (349.14, -358.02) | (102.49, 28.02) | ||
| PM BOSEMs | (-2736.5, 193.8) | (-2709.41, 224.14) | (27.09, 30.34) | ||
| power on baffle PD (mW) | 0.65 | 0.65 |
Didn't have time to do ETMX.
ETM OL calibration was done using red beam while red team was doing red things.
| ITMX PD1 | ITMX PD3 (wired to PD4) | delta claimed | delta physical | correction factor | |
| ETM bias slider (P, Y) | (229.4, 90.5) | (253.4, 60.3) | (24.0, -30.2) | (35.9, -36.0) | (1.50, 1.19) |
| ETM OLs | (-16.97, -17.62) | (21.50, 24.07) | (38.5, 41.7) | (35.9, -36.0) | (0.932, -0.863) |
| ETM top BOSEMs | (163.25, 183.36) | (276.98, 153.34) | (113.7, -30.2) | ||
| PUM BOSEMs | (1114.59, -678.99) | (1160.02, -715.61) | (45.43, -15.9 ) | ||
| Power (mW) | about 0.16 max | about 0.16 max |
Unlike ITMX, the OL PIT sign convention of ETMX is consistent with SUS convention, but OL YAW convention is inconsistent.
Also, unlike ITMX, ETMX OL amplitude doesn't seem to have a factor of 2 error.
Sign convention of SUS is: Positive P = pointing down. Positive Y = counter clockwise viewed from the top.
Not sure if Filiberto is complete but maybe...
As far as SEI work goes:
CPS racks are located and all wired up sans sync cable.
~75% of the in-air cables going to the Feed Thrus are Strain Relieved.
The harder half of the Dial Indicators are in place.
Cabling for SUS, ISC, and SEI are pulled and and connected to the feedthrus except for ISI Corner 1 Flange F6. Flange has DB25 connectors but should be 3 pin power connectors. Filiberto Clara
Daniel, Sheila, Alexa,
We pinned down the wandering peak in the IMC error signal. It was a beat note between the fixed frequency 78.2MHz and the IMC VCO. Moving the IMC VCO frequency (using the tune offset) moves it, it dissapears when the 79.2MHz is off. It becomes very small when the cable from the RF pacth panel in R1 to the doubler for the fiber distribution is disconnected from the patch panel, and can be small when the able is connected at the patch panel but not at the input to the doubler, perhaps depending on where the cable is. Disconnecting the output of the doubler has no impact. It seems like a purely electrical problem.
We still do not know why the UGF has changed, but the of the IMC error signal measured at Imon is 1.5V at the moment.
This is from last week.
We briefly measured the distance between optics and such, and used nanoscan to measure beam width/profile at various places though they were very very ugly.
See attached scribbling for layout (all dimensions in inches). Mirror names are arbitrary.
Measurement points are indicated by alphabet from A to I. Measurement points with prime (G'-I') means that the first lens in WFSB path (LWFSB1) was removed during the measurement.
The rest of the attachements are the nanoscan result. WFSB1.jpg-WFSB4.jpg=measurement point A-D. WFSA1.jpg and WFSA2.jpg=measurement point E and F. WFSC1.jpg-WFSC3.jpg=measurement point G', H' and I'.
The lenses as installed are:
LWFSA1 +250mm
LWFSA2 -75mm
LWFSB1 +250mm
LWFSB2 -100mm
This is an adaptation of the mode-matching solution by Bram Slagmolen used for the OAT WFS in D1100607-v10, and shown in the attached plots. This is not the simplest possible solution, but it has the very desirable quality of having great flexibility with WFS placement while keeping 90 (+/-10) degree Guoy phase separation.
It is important to note that the nominal mode-matching solution used to generate this layout did not account for the beam quality issues. In theory, the input beam should have been small enough that the beam expansion properties of the layout would have been necessary to get a usable beam size on the WFS. If this ends up being an issue, the mode-matching can be modified to reflect reality.
WFSa1.jpg in the original entry was bogus (it was a copy of WFSb1). Attached is the correct one.
J. Kissel Given that this morning's ETM motion provided for difficult arm cavity locking and CARM hand-offing again, I've continued to pursue the long-term stability of the X ARM ISI Performance, by studying the ISI performance at 3 different times. Here's what we learned (or re-learned) from the study today: (1) Today (2014-02-13 17:00 UTC) was a really high-wind day. Yesterday (2013-02-13 04:39 UTC) was a medium-wind day. Two days ago (2014-02-12 01:00 UTC) was a low-wind day. The green team really liked two days ago, they were marginally happy with yesterday, and could not get anything done today. (2) From Robert: "At the X-end, wind, which comes primarily from the Northwest and West and beats against the side of the building, tilting the building, slab, and ground. This motion is seen as increased signal in ground seismometers between 0.02 and 0.1 [Hz]. The corner station, being a shorter, squat building is much less sensitive to wind." (3) In the current configuration, with Level 3 controllers and TCrappy blends, The longitudinal motion of the ETM suspension point is dominated by RY motion between 0.2 and 2 [Hz]. (4) The Level 3 controllers and TCrappy blends attempt to get awesome performance between 0.2 and 2 [Hz], because -- during low-wind days -- the QUAD pitch motion at the test mass between 0.3 and 0.7 [Hz] dominates to cavity motion. When larger than ~80-100 [nrad/rtHz] @ ~0.5 [Hz], the 0.3-0.7 [Hz] angular fluctuations make holding the optical gain constant difficult, and due to the poor quality of the coatings in green the cavity is more likely to fall out of lock. (5) The wind / slab tilt does not obviously increase the ground seismometer signal between 0.3-0.7[Hz] band. (6) During high-wind days, 0.02-0.1 [Hz] pitch motion of the ETM supersedes the 0.3-0.7 [Hz] motion, increasing the RMS motion so much so that the green VCO regularly saturates, kicking the cavity out of lock, again above ~100 [nrad] RMS. (7) The TCrappy displacement sensor blend filter has a broad, factor-of-three-ish gain-peaking amplification hump between 0.01-0.07[Hz]. The filters were pretty good copies of L1's blend filters, where wind and 0.02-0.1 [Hz] motion is regularly pretty darn small. It's merely unfortunate that our ground motion is so volatile and different at these frequencies that we won't be able to use the exact same blend filters between the two IFOs. (8) In order to reduce the cavity motion below the saturation limit of the VCO, one could try to just offload the bulk of the control authority to HEPI along the IPC tidal path up to, say a little past the microseism (but before the QUAD suspension resonances to keep the loop design simple). BUT the ISI's TCrappy filters blend at ~0.06 [Hz], with a *ton* of loop gain from the Level 3 isolation controllers, so any motion injected into HEPI will get ignored / suppressed by the ISI's inertial sensors above the blend frequency. (9) The TCrappy blend filters we used in the design of the Level 3 controllers, and those particular blend filters are only "psuedo" complementary. Though this hasn't been thoroughly tested or confirmed, the belief that this means that TCrappy blends can *only* be used with the Level 3 controllers, and vice versa. The ISI had tripped one or two times while switching from this blend configuration to another, but there's not yet direct evidence that this marginal in-complementarity was cause. (10) The ITM is consistently performing better than the ETM, as measured by the optical lever -- but remember, it's unclear whether we can trust the short-armed ETM lever to be measuring pure pitch below ~0.5 [Hz]. (11) The ITM optical lever's signal consistently has some high-frequency fuzz on it, above 0.5 [Hz] that's clearly visible in the SUM. Stefan suggests we should investigate / replace the laser head to make sure this isn't mode hopping of an old dying diode. (12) One can monitor the blend filter status by watching the H1:ISI-ETMX_ST*_BLND_*_*_CUR_SWSTAT channels. At least in this case where we are using all TCrappy filters in FM5 of the filter banks, with the input, output, offset, and decimation buttons on, the bit-word is 7184. In conclusion, - We need to pay attention to tilt, not just the translational direction of the ISI. - Our performance is volatile, depending on the weather, so need to consider having windy-day vs. calm-day blend filters that we regularly are able to switch between without trouble. - We still have work to do on the ISIs. Sensor correction, which has not been commissioned on either X ARM platforms can perhaps help, but maybe not if we are blending so low. We should most certainly investigate a set of blends with less gain peak in the wind band.
A few things:
Wensday we couldn't get anything done either, in large part because of being tripped much of the day, and yesterday was actually better than Wednesday.
As far as complementarity of the filters, I know that I have been able to bring the ETM to level 3 on stage 1 with 250 blends, but that 750 blends tripped. Also, stage 2 has been at level 2 with 250 blends.
Also, Stefan and I looked at a strip tool yesterday of the control signal to the VCO, and ITM and ETM ST1+ST2 ISO_X output. One of The ETM was clearly moving in phase with the VCO control, and causing saturations.
J. Kissel, S. Dwyer, For reference, the green VCO range is df = 2 MHz (cf. LowNoiseVCO Wikipage). The equivalent length change is dL = 14 um. Calculation details dL / L = df_g / f_g dL / L = df_g / (c / lambda_g) dL = L * lambda_g * df_g / c dL = (4e3 [m]) * (532e-9 [m]) * (2e6 [Hz]) / (3e8 [m/s]) dL = 1.4187e-5 [m]
The data from this entry can be found in the Seismic Repository, under
${SeiSVN}/seismic/Common/Misc/2014-02-13_XARM_PerformanceASDs.xml
I added the dither signal paths in h1suspr2. This allows the dither signals to be separated from the ASC feedback.
I committed this change in the svn. The revision is at 7293.