Evan, Paul

Yesterday we repeated the beam size measurements on ISCT1, with the quieter ITMX.

First we measured the PRM direct reflected beam, in reflection of the window after the ISCT1 periscope. We misaligned ITMX and ITMY for this measurement, and also misaligned the ALS beam from X-ARM with the PZTs. Slight disclaimer with this beam: since it's in reflection from a non-AR coated window, there are two beams of roughly equal power, separated by only a little over 1cm. I would therefore be a little less confident in the x-radius data for this beam. If possible, at some time it would be good to use a pick-off mirror that avoids this problem for the PRM direct reflection beam.

Then we moved the nanoscan to a position in transmission of the window and measured ITMX and ITMY direct reflected beams. For those two measurents we misaligned PRM, ETMX, and the ITM that we weren't measuring the beam from. During this time, 4W was being applied to the IMTY ring heater.

The beam radii we measured were:

The ITM beams we measured yesterday were slightly smaller than we observed last time. For ITMX at least, the motion of the beam on the nanoscan was significantly less than last time, so these results should be more reliable. Rich switched on some seismic isolation before we measured the ITMY beam, which appeared to result in a DC misalignment of ITMY. We adjusted the alignment offsets to account for this and left it aligned in that manner. The alignment offsets that were in place before we began were:

ITMX was at P=92.8 Y=-65.9

ITMY was at P=19.2 Y=-140.7

ETMX was at P=250.7 Y=87.1

PRM was at  P=-685 Y=-447

Attached are the beam motion / radius ASDs from the logged data from the nanoscan. Comparing with the ASDs attached to aLOG 9773, we can see that the ITMX beam motion was significantly less this time.

1.  Cabling.

QPD, picomotor and beam diverter were connected to the cables coming from the ISI. We spent an hour or so just to connect the green QPD cable (D1000568 s/nS1104468), as the male pins of DB25 don't align well with the female pins and the male pins are sort of deformed. This is a known issue with this specific connector, and hopefully this is the last time we have to do this.

2. Hartman reference path.

Two Siskiyou mounts and optics for Hartman reference path were removed from the assembly, as these are not in the production units. However, periscope for Hartman reference path stays as removing it might change the weight too much.

3. Black glass thing.

Attempted to install 5 black glass beam dumps (https://services.ligo-wa.caltech.edu/integrationissues/show_bug.cgi?id=5), but couldn't. The issue is that the head of the tensioner screw on the Siskiyou mount that is holding the picomotors is slightly sticking out from the mirror mount surface, and this interferes with the beam dump holder (https://dcc.ligo.org/LIGO-D1002701).

For newer production unit we remove one washer under the screw head before assembling and the screw head doesn't stick out any more, but in this case we need to retrofit, and removing the screw to remove the washer means that the picomotors come out and the alignment would be ruined.

After some discussion with John Worden, he showed me how to mill using clean tools, and we milled slots for the beam dump holders such that the slot would accomodate the screw head.

Tomorrow morning I'll give them to C/B people so they could be cleaned in untra sonic bath and then air baked. I hope that this can be done by the end of the day, without these things we cannot do initial alignment as 5 pieces of black glasses are heavy enough to change the table balance completely.

4. IAS target not found.

This is another thing that are necessary for  IAS to do their thing. Doug may have these, Corey couldn't find them in the EX lab.

This morning the X-arm accidentally locked to what looked like a second order higher order mode of the ALS beam. The power of the transmitted light in arbitrary units was

This would mean about ~15% of the incident power is not mode matched to the cavity.

(Gerardo and Margot)
ITM03 and ITM11 have both ears bonded on, and are back in their cake tins for curing.
ITM03 S1 also had its fc pulled, and coating inspected as seen in T1400043. A “ thick balanced layer” was re-applied to face, leaving a small part at 12 o’clock position off for welding alignment. 
Pulled PEN-ETM08 out and staged, will get at least one ear onto it tomorrow morning (friday). 
CP05: Fiducial measurement staged and completed (had to get granite table moved to bonding lab, and equipment set up etc.) Left CP05 in flipper under flow bench for getting its prisms on next week. Measurements are on the dcc under E1400054.  
LHO large optics inventory: Went through cabinets here, then updated nebula location and install vs spare status for CPs, ITMs, LHO PEN-ITMs, LHO PEN-ETMs, SRMs, SR2s, PRMs, and PR2s. 

Just for your information, from Jan 30th-Feb 6th the IMC has had a duty cycle of 81.5% (according to the ODC) and attached are the ASD of IMC-F and IMC-X for this period (i.e. all the good time in the past week). Plotted are the median ASD of this time period with the 5th and 95th percentile showing the shaded regions. As you can see the spectra look quite stable. 

I have changed the controls account desktop DTT icon to read DTT-debug, and have redirected it to start a test version of diaggui which should solve a critical bug that has generated complaints for the last few years.  The bug involves the inability for diaggui to properly restore Reference traces to the plot window when read from a .xml file.  This should show up on new logins of the control room computers running Ubuntu.

The command line invocation of diaggui still opens the non-test version.

Please use the desktop DTT-debug icon if you would like to test this.  Feedback is appreciated.  Once further testing is complete, a new version of the gds tools will be released.

Reloaded the Local to Cartesien Matrices to correct errors (per T1000388).

This changed the Location Monitor numbers mostly in sign but some minor magnitudes too. The X Y RX & RY values changed signs.  I reset the targets with the ISI off (and HEPI position loops on).  The Rz value changed by a couple urads.

I added back the Beckhoff channels minus a new list of ones that appeared to be changing too quickly. This time the update rate appears reasonable. Conlog is now monitoring 97,308 channels (target_grep_channel_list_minus_fast_beckhoff.txt). The list of fast channels I removed is also attached (beckhoff_ro.txt).

Jeff B & Andres R

   We moved the HLTS suspension SR3 into position to have the metal Bottom Mass replaced with the Glass Optic. We took height and blade tip breakoff measurements as a pre-installation base line. All measurements are within tolerances. 

Measurement Point            Target/Tolerance  	                         Measurement 
Top Blade Wire Breakoff       806.12mm	                                 804.93mm, 805.89mm 
Bottom of T-Block                 552.23mm	                                 552.60mm
Top of Intermediate Mass     461.63mm	                                 461.63mm
Lower Blade Wire Breakoff   608.84mm tip coplanar <0.5mm  607.75mm, 608.11mm, Coplanar = 0.36mm
Top of Bottom Mass              291.0mm +-1mm	                         291.17mm

   The next step is to center and adjust the OSEMs, and then run Phase 2A Transfer Functions.  

Corrected daqdrc file, restarted daqd on h1nds1.

  In preparation for installing sensor correction I took a ground to platform transfer function to see what kind of coherence we have, short answer is lots from 0,1 to a few hertz

The aLOG will be down for maintenance tomorrow at noon (pacific time).

Please post or save your log entries before the maintenance.

I commented out the DC watchdog components in /opt/rtcds/userapps/release/cds/h1/alarmfiles/h1cds_iop_sus_watchdog_b123.alhConfig.

I finally got a script working to step the alignment offsets on the IMC mirrors and record the transmitted power drop with MC2trans and IM4trans QPDs. 

The idea behind this was to compare the quadratic function for power drop with misalignment with the theoretical function, giving us a means of accurately calibrating the alignment offsets.

The reason I'm interested in calibrating these offsets accurately is for beam jitter measurements using the coupling from jitter to RIN in transmission of a misaligned IMC [see e.g. LHO aLOG entry 8190]. The coupling factor is determined by the slope of the quadratic function, so we can't calibrate jitter measurements made in this way any better than we can calibrate the DC alignment offset.

The first attached plot shows the normalized transmitted power obtained for each individual mirror DOF, from both IM4trans QPD and MC2trans QPD, over "intended" alignment offset. Also included is a plot of the normalized transmitted power from a Finesse model of the IMC over "real" misalignment offset. From these plots we can see that in general the alignment offsets actually applied to the MC mirrors are larger than the intended alignment offsets. However, the measured data is not always symmetric (especially for IM4). This could be due to clipping at the QPDs. The centering on IM4trans is not as good as the centering on MC2trans, so I would be more confident in the numbers from MC2trans.

I fitted a quadratic function P=A(x-h)^2+k to each of the curves. The calibration is then done by scaling the alignment offsets applied to the actual suspensions by sqrt(Amodel/Adata). The second attached plot shows each DOF again, but this time with the x-axis scaled for the measured data to fit the model. I used the scaling factors calculated from MC2trans data since the centering on this QPD was better. For the most part I'd say the data matches the model well after this scaling.

These scaling factors are:

I would propose to include these scaling factors in the calibration of the MC mirror offsets.

The script can be run again at any time to check for any possible changes in e.g. the OSEM coil driver gains over time. It might be beneficial to take more data points at some point too, but the script takes 15mins or so to run as it is (mainly due to the time given for optics to settle between changes of offset). Another improvement would be to step MC1 and MC3 pitch over a larger range, since the transmitted power is actually fairly insensitive to these DOFs. Both these things can be edited in the top few lines of the script.

In case anyone is interested in running this script in future, it is located at opt/rtcds/userapps/release/ioo/h1/scripts/imc/pfulda/IMC_align_calibrate.py

Be sure to run the mcWFSrelieve script located in opt/rtcds/userapps/release/ioo/h1/scripts/imc/ first though!

I attach the analysis scripts here too, including the measured data, Finesse model and results, and other functions used.