I've set up a cavity scan to run as often as the GPIB-Ethernet/SR785 system allows (~ every 165 s), in preparation for observing shifts after the ring heater is turned on later today. Excitation B of Common Mode A will be left on for the duration of these measurements.
(corey, jim)
Have Capacitive Postition Sensor (CPS) mini-racks in place under HAM2 and they were powered up so leveling could be performed. While in the chamber we also cleaned up cabling a little. All of this was in efforts to prep this ISI for Hugo-testing.
[This is for work from Thursday]
(corey, hugo, jim)
HAM-ISI#7: Much of the day was devoted to helping out Hugo finish out items from his testing document (noting serial numbers, checking level, helping with tilt spectra measurements, etc.).
BSC-ISI#4: Optics Table Assy forklifted from granite table on to Stage0. Blade Posts were helicoiled and (2) of them screwed on to Stage0 (not torqued though). Did not put third one on because the dowel pin for it was a tight fit.
(work from Wed & today)
Before installing the HAM5 doors, wanted to connect the HAM5-ISI SEI in-vac cables to their respective feedthrus (roughly, not carefully dressed). This is so we can install both HAM5 doors today, but also still be able to have Vincent run basic sensor tests. The feedthrus were also labeled on the outside.
MC1 and MC3 HSTS have been moved to the LVEA. MC1 is placed (facing North) on the South end of the chamberside table and MC3 is in its storage container.
It seemed that the Arm caivty dropped lock, and th FIBR servo was railing (with the beat frequency at 79 MHz). I had a quick look around, but could not see anything wrong. I tried to relock the fiber with no success. I left the FIBR and Arm unlocked.
[Daniel and Bram]
With the appearance of the laser PZT resonance in the FIBR servo loop, we made a notch filter. We measured the PZT resonance in a previous entry 3857 to be at 287.55 kHz. After some searching and going back and forth we decided to go the easy way, using a passive notch filter (schematic attached 'FIBR_PZT_NOTCH.pdf'), which Daniel already has used in the TTFSS.
By the lack of finding the right capacitors, we used a 500 pF and a 100 pF parrallel, with a 0-100 pF variable capacitor (oh and we got a 470 uH SMD inductor!). With the help of EE-Dave we managed to pack it into a pomona box.
Also attached is a discustingly bad phone photo of the measured response (the RF analyser has a naughty floppy disk drive).
All in all success. We plugged it in and it worked, we can lock the FIBR Servo with a UGF of 28 kHz (another log entry will follow when I get the data from the disk).
The measured open-loop response is seen in the attached tiff file.
Upon returning from vacation I was annoyed by the fact that launching firefox as controls from any of the cds workstation takes forever (more than 5 minutes). I eventually found that the firefox command was overridden by a launcher script (/ligo/home/controls/bin/firefox) that rsyncs user profile to /tmp/somethingsomething, and unfortunately it copies seemingly useless things like Cache.Trash******* that contains over 3.8 million files!
Cache.Trash seems to serve some purpose when firefox exits abnormally and tries to recover session information, but somehow it keeps growing because of firefox bug. I just deleted Cache.Trash.
In addition, though I don't know why you want to rsync your user profile to /tmp, I changed the launcher script so rsync excludes Cache.Trash (or anything starting Cache). I don't care if the previous session is not recovered.
One of the goals of the OAT was that the residual arm motion measured by the green beam, with the VCO to arm offloading, is about 10 nm or so for f<0.5Hz.
Attached is the calibrated residual motion in nm/sqrtHz. Solid lines are with both ISI isolated (non-aggressive crossover, without Trillium), and the dashed are with both ISI only damped. These are not a true A/B comparison (different lock stretches, different seismic level, only 7 averages) but are good enough to show you some ball park numbers.
1. Even though the isolation helps greatly at 1Hz, it makes a huge peak at about 40 to 50 mHz with the RMS of about a micro meter. This might or might not be larger than expected, but as I understand from Vincent we expect some amplification at this frequency.
2. With or without the isolation, 0.46Hz peak is also big. Isolation might be helping a factor of 2 or so but we need a factor of 20 or more.
3. Though it's outside the scope of the stated OAT goal, 1Hz peak is not negligible. Without isolation, this should be reduced by a factor of at least 5 or so.
Vincent might be able to refine ISI further, but we shouldn't expect HEPI/ISI alone to bring the residual RMS down to 10nm level (or even 50nm for that matter, stated goal of OAT for HEPI/ISI is 200nm RMS and we're already quite close).
Regardless of the ISI isolation, we need a more aggressive VCO offloading to the length. Right now VCO is only offloaded to the HEPI, and the UGF of this path is smaller than 10 mHz. We need to use another path to the ETM and/or ITM suspension if we want a larger UGF to suppress e.g. 0.46Hz peak.
The reason why no work has been done for this for a long time, I think, is because there was a huge POS to PIT coupling when you drive M0. What's the current status of drive diagonalization (don't confuse this with sensing diagonalization)?
Message received by team SUS. We'll think on it.
The latest measurement of the ETMy M0 Diagonalization was earlier this year on May 21st. The attached PDF contains the M0 Vertical and Yaw DoF diagonalization measurement results. The motivation behind the measurements was to drive the OSEM coils at a single frequency within the resonance band for the Vertical and Yaw DoFs and measure the transfer function between this drive and the individual OSEMs. The desired result was to have the individual OSEMs not contributing to the drive signal have a response at least 15dB lower than the driving OSEMs. The Yaw DoF was driven at 1.3Hz with a 25-ct amplitude. The Yaw DoF is comprised of the M0-F2 and M0-F3 OSEMs. The response of the remaining OSEMs (M0-F1, LF, RT, SD) was at least 28dB lower than the drive signals. The Vertical DoF was driven at 2.2Hz with a 1000-ct amplitude. The M0-LF and M0-RT OSEMs constitute the Vertical DoF. The response of the other OSEMs was at least 23dB isolated from the driving OSEMs.
[Mike R., DF] We have placed a number of mirrors on the H1 PSL table to divert the beam after the periscope to the FI testing and alignment area. This was done by: a) moving three 1" IO_AB mirrors from their intended to new temporary positions b) placing three 2" mirrors from the eLIGO POY and POB on the table. The full setup will also require an HWP to control the polarization of the beam sent into the FI, and (maybe) a lens to get the correct beam size at the location of the FI. Note: the schematic diagram below does not properly identify the identities of the newly placed/moved mirrors, only their positions.
This morning Deepak brought several parts for the IO Faraday Isolator which had just come out of the bake oven, and I began putting the FI together. The assembly was performed in the H2 PSL enclosure, and so far does not include any optics, so it really is a "fit test". Everything fits, although some mods have to be made compared to the FI mechanical assembly E0900301-v5: 1. Same as at LLO, the removal of aluminum shims from between the rotator magnet and the magnet base resulted in magnet not being solidly held by the omega-shaped clamps. Same as at LLO, this was solved by inserting the same shims between the magnet and the omega-clamps on the upper side of the magnet. 2. The spacer plate is much thicker at LHO, and so 1" long screws are way short for attaching the magnet assy and spacer to the breadboard. 2" long screws work better, and I'll need to get more of those from the SUS people tomorrow. 3. Same as '2' for the HWP picomotor assembly and insert. This is close to what can be accomplished without inserting the optics.
Elli and I took transfer functions of the OLTF using common mode B. The optimal gain setting was found to be -14. This results in a UGF of approximately 10.4 kHz while keeping the resonance at 42 kHz below 0 dB (maximum about -2 dB).
At higher gains (-10, -12, -13), the 42 kHz peak was consistently greater than 0 dB.
I ran some ring heater measurements this morning. I incrementally increased the requested current from 0mA to 29mA in units of 1mA. The power radiated from the ring scales as the current squared. We were radiating aorund 6-10W at 630mA requested. With these measurements we would've been radiated no more than ~22mW.
The calculated resistance of the ring heater is 33.93 Ohms for Segment 1 and 34.06 Ohms for Segment 2.
There are some offsets and gain settings between the requested and measured currents that I need to fix.
PR2 was installed in HAM3 today, and traveled well on the Genie and Arm. It's sitting against it's cookie cutter, and dogged down overnight. The crew was Kurt Buckland and Scott Shankle, as well as Deepak and I
Pictures:
During course of R&Ring center down-facing feed-through flange and extending purge air header beneath HAM1,2.
Noisy day, which permited lots of noisy activities.
[Jax, Aidan, Elli]
This morning we calibrated the lever arm of the HWS. We added a beam splitter (CAL-BS) into the optical path to hit the HWS CCD with two beams (REFL and TRANS) at ~ 10mrad to each other. We removed the Hartmann plate from the sensor and recorded the resulting interference pattern on the CCD. The spatial frequency of the interference pattern allowed us to determine the exact angle between the two beams, 9.86mrad, with a precision of approximately 1:500. Next we replaced the Hartmann plate and measured the Hartmann sensor spot pattern of each beam separately by blocking first one and then the other beam. We centroided the spots and determined the mean centroid displacement, 8.507 pixels. Knowing the measured angle, the pixel size (12E-6 m) and the spot displacement, we determined that the lever arm distance (between the Hartmann plate and the CCD) is 10.35 +/- 0.03mm.
The data is attached. Also attached is an optical layout showing the additional beam splitter producing the reflected and transmitted beams.
We made certain to remove the beam splitter and check the final alignment of the HWS system was restored to nominal before closing up the ETM ALS table.
The reference lever arm that has been used before now is 10.0mm.
Replaced the fuse for the dust monitor in the clean room over HAM 3 (LVEA location 15). Restarted the EPICS IOC. Added a dust monitor in the clean room over HAM1 and 2 (LVEA location 9).
Collected as much serial number as possible on the nearly completed HAMISI#7 (just a few remaining tests for it). There was one item I was not able to get, namely the a Flexure; it was oriented in a way that made its s/n NOT viewable (waiting to see if someone jotted this info when they built the system). Below are all the other s/n's:
Stage0: 014
Stage1: 010
Optics Table: 009
Corner1
Actuators
GS13s
L4Cs
CPS Sensor
Flexure: -- not viewable, installed upside-down :(
Spring: 030
Support Post: 031
Corner2
Actuators
GS13s
L4Cs
CPS Sensor
Flexure: 046
Spring: 041
Support Post: 017
Corner3
Actuators
GS13s
L4Cs
CPS Sensor
Flexure: 040
Spring: 045
Support Post: 032
