After all the succes of the RefCav and the PLL, we managed to restore the cavity alignement. We had to do some serious beam steering (with the ITM we steered the beam on either side and top and bottom of the ETM to centre the beam). Once we had some locking going out tdsdither script walked us to the top.

Engaging the PDH (CMB-B) servo initially it seemed to lock ok, but then the servo output started to oscillate between +/-10V. All gains seem ok (we even increased the input from -14 to -10 dB), with a 'UGF' of 11 kHz.

With this oscillation (at the limit), we were seeing the power fluctuations on the REFL_PWR_MON. I left the arm cavity unlocked, but kept the PLL going.

On another note, we did find the moment to align the WFS, so when we get the oscillaitons under control we can get the WFS going ...

If one wants to restore to a 'good' epics state for the ISC and SUS (I/ETMY) at LHO, local time of 1800h 24 July 2012 is good. It has the various gains correct and ITM and ETM offset so there is a resonance for locking. The PLL will be on, but the PDH servo is off.

Although the ISI was working as well, I think that Frabrice has made soem changes since.

A new low blend has been designed and installed on ITMY, Stage 1, longitudinal.

The plot attached shows the improvement on the stages motion. The red curve is the reference (Damped), Blue curve is a measurement with a 250 mHZ blend, green curve is the measurement with the 100 mHz Blend.

L4Cs are the in loop sensors and show a very nice suppression.

T240s are out of loop and also show good suppression, though not as good as the L4Cs. We'll investigate why (sensor noise, misalignment...)

GS13s show some suppression, but less than on Stage1. To be investigated as well.

for about an hour starting at July 24 2012 ~1900 PDT, July 25 2012 0200 UTC as requested by his daughter who called the control room as she was about to start. I gave her approval, after knowing from a prior conversation with Bram as he was leaving for the night that "the cavity is in a unstable state at the moment for unknown reasons"  and he's left it unlocked for the evening. 

[Alberto, Bram]

Today we were able to locke the ALS PLL again with similar settings as we used before. The laser temperature was 42.10 degrees when the beat note was at the working point frequency (40MHz).

We don't clearly understand why yesterday the laser temperature couldn't go above 38.45 degrees. Maybe the laser was getting some unwanted offset at the slow input from the slow controls connection? We didn't check that.

[Alberto, Bram]

Today we locked  the reference cavity with some optimized settings. We set the knobs in the TTFSS with these values:

COARSE: 690; FINE: 610; COMM: 988; FAST 520; OFFSET 294.

The laser temperature diplay read: 41.064 degrees.

We measured a UGF of 172 kHz.

Two peaks appeared initially in the loop gain measurements at about 2.4 Hz and 4 Hz. We found  that the first was due to the cleam room HEPA filters and the second one was the cavity motion due to us touching the table.

Attached are plots of dust counts > .5 microns in particles per cubic foot.

Got 6 of the 8 HAM3 HEPI Actuators attached today.  Would have been complete except for the 3 Up Vertical Lock Screws which can bind if they are turned too far out and they aren't well centered in the F-Clamp.  Or if they aren't turned too far out but aren't well centered and then you raise the whole system such as when you are correcting the elevation.  This is what we did yesterday.  This morning when I started the Actuator attachment, I found these set screws had bound on the back side.  After freeing them, the system slewed off to Narnia and I spent the majority of the morning getting the position back.  As I said, getting good at this.  Just the NW corner left.

Alberto and Bram

The Innolight laser lock fine to the fiber beatnote. The temp setting are at 42.1 deg C. The UGF is 21.5 kHz.

We had to change the CMB-A input sign from '-' to '+'. Also, the Temperature controller in the Beckhoff has a sign change.

Now we relocking the arm cavity.

• Ace porta-potty
• Unifirst on site
• Wooden crates picked up
• Dave added Hartmann sensor channels to the DAQ
• Hugh at HAM3 working on actuators
• Travis working in optics clean room by HAM3
• Thomas working on oplevs at EY
• Gerardo checking on vacuum equipment at BSC1-3, HAM4-6

After relocking the RefCav in the optics labs at the nominal settings from early yesterday, and tweaking the servo settings (UGF ~170 kHz!).

I took an SR785 spectrum of the RefCav transmitted beam and the ~2.6 Hz resonance is clearly visible. After turning off the HEPA filters, they dropping in amplitude, but a 4Hz spike appears.

The RefCav table has its HEPA filters turned OFF, hope that is ok.

Data will follow shortly.

After yesterdays failed attempts at seeing drive on the MC2 M2 and M3 lower stage coils, Richard checked the electronics and found nothing.  So, we really think we just can't see the drive of these small AOSEMs.  Nonetheless, for the record here's what he checked and found to be healthy:

1) The signals on the cable from the satellite box to the AOSEMs

2) The signals on the cable into the satalite box

3) The satellite box lights were all green where appropriate

4) The offsets entered on the medm input were seen on the coil driver cable in

(Richard M, Gerardo M)

Attached is a comparasion of the iLIGO illuminator vs. a new illuminator (consists of 3 sets of LED lights) illuminating the inside of BSC05.

The conclusion is that the new illuminator works good as is, but Richard will add one more set of LED lights to the new illuminator to increase its illuminance.

Photos below:

iLIGO = iLIGO illuminator

New = New type of illuminator

Betsy, Filiberto and I tested the signal chain for the MC2 lower stage.  We were able to confirm Sensor signals are reading back.  The Coil driver drives a signal to the SatModule in the right order.  We also checked that Coils,PDs and LEDs were all on the appropriate pins of the cable from the SatModule to optic.

We installed a Beckhoff analog input module and uplink in the optics lab to monitor the RefCav transmission photo diode.  This temporary setup has an Ethernet cable from the optic lab to the MSR plugged directly into the Beckhoff Front End computer.  The photo diode signal it split off the BNC and converted to twisted pair and plugged into the beckhoff 3102 module.  At some point I need to extend this Cat5 cable to clean up the installation but the signal can be seen in the beckhoff system.

Starting this weekend, the slow down of the front end epics systems started on the H1 systems as h1boot was being backed up by cdsfs1. This is identical to the H2 problem which started July 4th.

Investigation is continuing, but for now the short term "fix" is to only rsync h1boot at 05:20 each morning. h2boot is rsynced at 05:40 each morning.

Changed gds software from gds-2.15.2 to gds-2.16.3 for linux workstations in control room.

Jeff K, Jeff G, Thomas V


We thought it might be necessary to map out the quadrants of the ETMY and ITMY optical levers via offsets induced onto the suspension stages, namely M0.

After centering the beam on the optical lever QPD on ETMY, we offset the pitch on the M0 stage by a positive amount and expected the two lower quadrants of the QPD to have a spike in intensity (as deduced by the coordinate system set by SUS to determine which direction is positive and negative pitch and yaw).  Then offset yaw in a positive amount, which we expect to see the the two left quadrants to have a spike in intensity.  This was different than was what showing as pitch and yaw in the SUS medm and also is different than what I had used in my earlier calibration parameters.  This being said, the outcome of the mapping is as follows as viewed facing the QPD for ETMY:
13
42 

Repeating the test with the same process on ITMY OptLev, we found that the mapping didn't correspond once again to what was previously recognized as the mapping and is as follows:
42
13

The plot thickens:
As you can see, the two QPD's are not the same rotated about the center axis, which begs a confusing question of what might be going wrong. The most obvious answer is that the pitch signs are flipped, but where might this come from?  It could be a wiring issue in the hardware connecting the QPD to the ADC, a problem with a few negative signs somewhere in the readouts, or a difference in polarity of the output coil drivers F2 and F3 on the M0 stage of the ITMY.  The last option was found when we were trouble shooting and found that aLOG 2109 written by Jeff K. had addressed this issue but we couldn't find a log that resolved it.  It might be a combination of these things, still a work in progress.  It might be worth it to put in the glass viewport protectors and remove the enclosures to do a laser pointer test again on these QPDs.  Either way, the discrepancy between the two scenarios via the same process is perplexing.

This afternoon we obtained the spectra of the lower stages (M2 and M3) of MC2 in both the damped and undamped states (using plothsts_spectra.m).  The spectra were taken over the lunch hour so the LVEA activity should have been pretty quiet.  Data was committed to svn.  WIll post a PDF shortly.

As well, I used awggui to try to verify that I could see drive on the coils of these lower stages (for example, exc H1:SUS-MC2_M2_COILOUTF_UL_EXC while watching the OSEMINF_OUT_DQ channel for UL).  This will need to continue later as at first pass, I couldn't see much signal on the M2 AOSEMs.

I have taken the calibration data and analyzed it. The plot of the linear response curve is attached.

I used a polynomial fitting program in python to get these numbers.  This should give you the conversion from volts to micro-radians.

           Slope            Y-intercept
Pitch   [  1.01902201e+06   8.42886118e+00]
Yaw     [  9.83122943e+05  -1.19329010e+01]