hugh.radkins@LIGO.ORG - posted 13:11, Monday 15 December 2014 (15618)
ETMY EndY BSC10 HEPI Locked onto Stops
Secure for pushing & pulling.
Secure for pushing & pulling.
ITmy and ITMx HWS have both been aligned so that the green beam from the X-arm returns through the two irises and onto the respective HWS's. To do this I had to move both of the upper and both of the lower periscope mirrors about an inch to the right. No other optics were touched. I took some pictures of the original beam path. The beam going to the ITMy HWS looked clean as came onto the table (image 1), but clipped the periscope (images 2 & 3). There were a few beams coming from ITMx, but the brightest one missed the periscope entirely. I aligned the brightest beam to the HWS.
Once the green beams were returning to both HWS cameras, I tried looking at the HWS camera images to fine tune the alignement. I could open a camera image using the command
/opt/Hartmann_Sensor_SVN/release/bin/stream_image_X/distrib/stream_image_X/opt/Hartmann_Sensor_SVN/release/bin/stream_image_X/distrib/stream_image_X
but I couldn't see a beam in this image. I tried shining a flashlight on the cameras, including without the Hartmann plate for ITMy camera, but the image didn't change. Either the camera exposure needs to be increased (seems doubtful), or the camera image isn't updating properly. Once I've figured out how to get the camera image I'll go back and fine tune the alignment.
In summary, the health of the laser is okay. The first plot is of the output power of the frontend laser pump diodes, D1, D2, D3, and D4. The output power decline for D1 and D2 is fairly small, declining about 2.5% over the last 6 months. For diodes D3 and D4 the picture is less clear as the signal is a little noisier, but it looks like about 5% over the last 6 months. The second plot is of the diode currents. DCUR1 corresponds to the currents for D1 and D2. DCUR2 for D3 and D4. Considering that none of us have explicitly changed the diode current this should appear constant (and it does). The third plot is of the output power of the various stages in the power amplifier. The fluctuations in the power monitors for stages 1 through 3 might be due to relative humidity fluctuations in the LAE. The output of the frontend laser decreased by ~2 W about 120 days ago. This might be a real power decrease or the alignment of the beam onto the monitoring photodiode. The NPRO output power has steadily declined. Attached are 3 plots of the NPRO output power. 6 months, 2 years and going back to May 2012. To recover some out the output power, we should consider increasing the diode current. /* Note the frontend diode box was switched out on June 6th, 2014. */
Restarted cds wiki computer, it was unresponsive.
model restarts logged for Sun 14/Dec/2014
2014_12_14 14:27 h1fw1
2014_12_14 20:42 h1fw0
both unexpected restarts. Conlog frequently changing channels report attached.
In preparation for venting in the morning the Y end is laser safe.
As Richard requested I first removed the interlock jumper, the laser turned itself off. I've replace the jumper now, and left the key on top of the controller.
The end Y picomotors are software disabled.
Stefan, Sheila
We burt restored ETMX and ETMY sus models to december 3rd at 19:00 UTC. The difficulties with DIFF yesterday were caused by wrong filter settings probably due to a bad burt after the model restarts. We then had no problem locking ALS both DIFF and COMM, with the green WFS and tidal feedback on. The guardian is not yet controlling the tidal feedback correctly once ALS COMM and DIFF are locked. We need to think about how to get the common signal (from MC-L) to the tidal servo, possibly adding it in the front end.
Once we turned of the sensor correction DRMI locked well. We saw that the AS 36 signals were saturated so we changed the whitening gain (1 stage of whitening filters, gain of 30dB). We spent some time trying to close some loops on the SRC, we closed both AS_A 36I-> SRM in pitch and yaw. We were not convinced that either loop really works; when we misaling SRM, the error signal doesn't change much before we start mode hopping and the error signal becomes unusable. We also closed the AS_C -> SR2 pitch loop, while it did bring the beam to the center the SRM loops had truoble keeping up. We think the next step is to try using SRY and set the output matrix to a combination of SRM and SR2.
Stefan, Sheila
Today we had difficulty locking DRMI, we tried PRMI and found we had difficulty locking that as well. Then I found that I couldn't even keep MICH DARK locked. Stefan was able to keep it locked by turning the gain up to -1000, removing the limiter from the BS M3 ISCINF once it locks, and adding a boost (FM4 in LSC_MICH). I compared the control signal to what we saw on decmber 3rd at a time when DRMI was locked, and see that we have about a facotr of ten higher RMS, all due to motion below 0.2 Hz. I then tried turning off different parts of sensor correction, first just the ISI XY, then also the HEPI Z. turning off HEPI Z brought the RMS back down to the old value. For now I'm leaving it all off.
BS M2 DRIVEALIGN L2Y gain changed from -1 to -0.8. This significantly improved the BS DC balancing.
K. Venkateswara
Looks like Z sensor correction is producing excessive Rz (Yaw) motion of Stage 1 at all three CS BSCs, but particularly so at the Beamsplitter. Attached plot shows the ASD of the CPS_RZ from the same period. The REFs were taken when Z sensor correction (to HEPI) was ON for all three, and the normal traces were with it OFF. While the sensor correction reduces motion at ~0.15 Hz, it is unexpectedly inducing excess RZ in all three, but much more so in BS. The coherence plot on Page 2 shows that RZ of the BS was the reason the MICH was difficult to control.
I don't have an immediate answer but will investigate some more.
I think one solution to the above problem is to turn on Z to Rz subtraction and enable the Rz loop. Jim and I tried this last week briefly and the result appeared agreeable. So I tried it again at ITMX and the results are shown in the attached file. First page shows the CPS_RZ, second shows the T240_RZ and the third shows the OpLev_Yaw. Green curve is with no sensor correction, blue is with Z sensor correction to HEPI and the red is with Z sensor correction to HEPI and Z to Rz subtraction at Stage 1.
I will also try this at BS and ITMY chambers.
no restarts reported. Conlog frequently changing channels report attached.
I just discovered that the PLC2 ecat systems at both end stations were restarted. Last restart reported:
X1PLC2 16:08 12/13 2014
Y1PLC2 16:32 12/13 2014
With both WFS and tidal running on both arm, we quickly tried DIFF. It failed. We took out the clearing of the drivealign filters, which was the first culprit. But it still failed. Some more work is needed on DIFF. COMM however worked just fine.
The green slow and tidal servos have been engaged. This is done through the arm guardian which in turn select a corresponding state from the ALS auto-locker. These states are "End Locked", "Slow Engaged", "Transition" and "Red Locked". With "End Locked" neither the slow nor tidal servo are engaged. With "Slow Engaged" they are both on, tidal feedback only in "Transition" and tidal and common mode feedback in "Red Locked". These three new feedback paths use the new integrator filter module. When the green PDH is not locked, the integrators are bled off.
The feedback topology is as follows:
The "Red Locked" state triggeres on the transmitted red power. Once in this state, it no longer matters whether green is locked. It can only transition back, when the red lock is lost.
Here is a 1.33 hour trend plot. Both the arm and tidal error signals stay within a few µm of zero, whereas the HEPI drive slow ramps upwards to 8 µm. With the WFS enagaged the arm power is solid. (The jump towards the end is due to some stray light from the x arm.)
Here is a 21h trend plot of both green arms. WFS & tidal get a thumbs up.
Evan, Stefan Did some more WFS/camera loop work on both arms: - Added a 0.3Hz LP with a notch at the main pendulum modes into the WFS output filter modules. This allows for a ~3-5 times higher gain. - Carefully measured the output matrix for the camera loops (X and Y arm, yaw and pitch) by dragging the ETM around and letting the WFS follow. The new output matrix values are in the snaphots #3 below. With them the camera loop no longer relies on gain hierarchy - it's gain was increased ~x10. - Some gains were redistributed - see the attached snaps. - Cleaned up the arm Guardian. Removed all old slow feed-back stages, and instead added a state commanding Daniel's new setup. - Added a WFS relief step to the Guardian.
We noticed that the higher Camera gain can cause a too big kick during the WF engaging process. Thus we used the existing FM triggering to set up a 10 second delay. During those 10 seconds the DoF3 (P&Y) , i.e. the camera loops, have 20 times lower gain. This seems to take care of the engaging problem. The attached snapshot contains all elements that changed.
The experimentally measured output matrix to move TMS, ETM and ITM simultaneously to center the ITMX green camera (without misaligning the beam) is
X PIT: X YAW:
ITMX: 0.68 -0.43
ETMX: 1.00 1.00
TMSX: 1.43 1.00
Y PIT: Y YAW:
ITMY: 1.43 -1.23
ETMY: 1.00 1.00
TMSY: 1.54 1.15
The expected matrix would be
PIT:
ITM: 1.06 = -g1
ETM: 1.00
TMS: 1.00
YAW:
ITM: -1.06 = g1
ETM: 1.00
TMS: 1.00
This means that our angular actuation calibration is somewhat fishy...
For reference, the H1 installed optics radius of curvature are (from https://galaxy.ligo.caltech.edu/optics/, after coating measurements):
ETMX: ETM-08: RoC=2242m ± 2m, (LIGO-C1103233), g2= -0.7817
ITMX: ITM-03: RoC=1940m, (LIGO-C1103237), g1= -1.0590
X Arm length: L=3994.4704 m ± .3mm (alog 9626)
ETMY: ETM-12: RoC=2240 ± 2mm, (LIGO-C1103257), g2= -0.7832
ITMY: ITM-11: RoC=1939.4m, (LIGO-C1103255), g1= -1.0596
Y Arm length: L=3994.4691m ± .7mm (alog 11611)
model restarts logged for Fri 12/Dec/2014
2014_12_12 11:11 h1iscex
2014_12_12 11:14 h1iscex
2014_12_12 11:26 h1iscey
2014_12_12 11:28 h1fw1
2014_12_12 13:41 h1fw0
two unexpected restarts. ISC code changes at end stations (no daq restart needed). Conlog frequently changing channels report attached.