Jim, Corey, Hugo,
The following L4Cs were huddle tested after reception from shipment #3759:
Specra are attached.
Test data is availabe in the SVN.
Gerardo and I are attempting to align the optical lever, we are able to hit the ITM relatively easily but on the reflection back to the QPD, we get this terrible scattered pattern shown in the pictures attached. We thought it might be the telescope so we switched it out and it just gives us a different scattered pattern with fringes. It is clear that there are multiple reflections and fringes but we tried hitting all parts of the ITM to make sure we're not clipping somewhere and it doesn't change the pattern. We also looked at the beam coming out of the telescope and it looks very circular and focuses down well, approximately 25 meters away the spot size looks about 2 or 3 mm in diameter. So I'm confused, I'm thinking maybe during installation and de-installation the telescopes got bumped and need to be refocused(which I've never done before), or we're using the wrong ones all together. Another weak point would be the fiber optic cable getting crimped, but there's a possibility that we're hitting something inside the chamber is messing up our reflected beam (the pattern looks very similar to Van Gogh's Starry Night). Investigating causes now.
Paul Schwinberg, Peter King, Rick Savage We found that when we increased the gain of the frequency stabilization servo (Table-top Frequency Stabilization Servo - TTFSS D040105 Rev. B S/N LHO03) to achieve the required bandwidth of around 400 kHz the servo lost lock frequently and had difficulty re-acquiring lock. Investigations with the RF spectrum analyzer revealed peaks in the Open Loop Transfer Function (OLTF) presumably from resonances in the phase-correcting EOM (Pockels cell) near 793 kHz and 1.8 MHz. (See OLTF.TIF, attached) We loaded C16 = 150 pF and tuned the existing notch in the Pockels cell path to 793 kHz using C50. (See NOTCH.TIF, attached) We then added a 20 pF fixed capacitor and a 25 pF variable capacitor in parallel wired in series with a 220 uH inductor and installed between the upstream side of L2 and Ground. This was tuned to give a second notch in the PC path at 1.8 MHz. (See 2NOTCH.TIF, attached) Then, by locking the TTFSS with only the FAST path (PC path disconnected), we found a peak in the OLTF at 35.7 kHz which is likely from the FAST actuator (piezo) in the NPRO. (See FASTONLY.TIF, attached) We tuned the notch in the FAST path to 35.7 kHz after changing L3 to 1000 uH and C49 to 18 nF and 2.2 nF wired in parallel. (See FSTNOTCH.TIF, attached) After some tuning with the TTFSS installed, the OLTF was measured with the TTFSS locked using only the FAST actuator. (See OLTFFAST.TIF, attached). With both the FAST and the PC actuators connected, the crossover was adjusted and the loop UGF was set to about 400 kHz where we have about 50 deg. of phase margin and close to 20 dB of gain at 100 kHz. (See OLTF3.TIF, attached) The loop operates robustly in this configuration. Prior modifications: As found (and verified): R50 = 499 Ohm C62 = 1000 pF R44 = 4.75 kOhm R41= 24.9 kOhm
Attached are plots of dust counts > .5 microns.
- Leak test at HAM1, HAM2 - Still pumping y-beam manifold - SUS testing at EY, many alarms, watchdogs tripped all day - ALS working with IAS at EY - Ops: Meeting with PSL at 1pm tomorrow (Thursday) - PSL: crew working late (past 6:00pm so far) - Apollo - ICC, installing panel for Ski, backflow preventor for LDAS room - ICC upper section of BSC2, cleaned about ring, moved flooring, half chamber bottom - OpLev: Thomas aligning the OpLev beam on ITMY - CDS: rebooted h1daq - MichaelR replacing laser safety signs across the site - Ongoing discussions about viewport acceptance and installation - Temperature setpoint raised from 67-70F in LSB lab areas - Aidan coming next week and wants laser hazard in some areas - OSB doors locked at 4:15pm - Heavy rain in the evening
I tested on H1 DAQ and then released it on H2 DAQ. Some DAQ restarts were necessary between 16:00 and 17:00 today.
New data concentrator startup code takes the current set of INI and PAR files and puts them into a location removed from the RCG modification area. All DAQ components (concentrator, frame writers and NDS) have been reconfigured to use the saved configuration set and not the default area. Now if a frame writer or nds is restarted after an INI PAR file change, they run with the saved configuration and not with the latest configuration, maintaining configuration sync between all DAQ systems.
Code change to /etc/init.d/daqd_dc0 on h1dc0 and h2dc0
...
daqdir="/opt/rtcds/lho/h1/daq"
...
# Copy INI and PAR files to a secure location and create a master file which references them
# This will permit restarts to frame writers and nds machines against the channel configuration
# at the time of the data concentrator start, and prevent modified INI and PAR files from being used.
# D.Barker 23May2012
# INI and PAR files copied into a directory named by the current date-time
# a symlink called running is pointed to the latest directory
DATETIME='date +%d%m%y_%H:%M:%S'
#echo "${DATETIME}"
mkdir ${daqdir}/${DATETIME}
rm -rf ${daqdir}/running
ln -s ${daqdir}/${DATETIME} ${daqdir}/running
for f in 'grep "^/opt" /opt/rtcds/lho/h1/target/h1dc0/master'
do
#echo $f
cp $f ${daqdir}/${DATETIME}
done
# create new master file referencing this running configuration
for f in ${daqdir}/running/*
do
echo $f >> ${daqdir}/running/master
done
# End of INI-PAR copy change. DB.
And the change to daqdrc file in all DAQ systems (h1 system shown):
...
set master_config="/opt/rtcds/lho/h1/daq/running/master";
...
3 of the ~20 joints tested to this point are big leaks -> Bolts of leaking flanges feel "wrong". Bolt torque is uniform but bolts feel "soft" and far too compliant. Not sure if they had yielded on initial install or maybe wrong alloy? (Hex head silver plated - where did these come from?)
Bolts from MDC PO 75ADV-S120059. Bolt kits specifically for Conflat Mounting.
JimW EricA Greg This morning we disconnected the HEPI Actuators because the YAW correction needed by IAS was ~200urads or about .4mm at the HEPI foot. The range of motion is only +-1mm, plus, the attached actuators will fight that amount of motion and cause non-expected responses. Jason tweaked up the IAS gear and gave us the confirm on moving. We brought it from 180urad CCW to 15urad CCW with 1/4 of a turn on each of the big Double Start Counter Wound (DSCW) HEPI Springs. After lunch we set to reattaching the Actuators and while we'd like to see better centering of the Actuator Plates for max range of motion I think it will be plenty. We'll have to really do driven range of motion measurements to determine this. In the end based on the Dial Indicators relative the last In-Chamber Vertical survey of the optical table and post this mornings move and OK by IAS, HEPI has Yawed the Optic from 15urad ccw to 35urad cw (still in spec). We also improved the level of the optical table, depending on how the tilting of the HEPI actually translates into the tilting of the optical table, from 0.5mm p-p to 0.3mm p-p. So again all good; really we just got lucky. I've attached a few pages from my logbook recording the in-chamber vertical survey and all the HEPI DSCW Spring adjustments and the Dial indicators readings. Let me know if you want a guide or tour.
Brushing of BSC2 was completed and first vacuum started.
Unexpectedly, I found the ETMy undamped this morning and the loop switches in an inconsistent state of on or off. I restored the switches to their appropriate on or off and enabled the damping on R0 and M0. THe suspesnion should remained damped at all times. It might, however trigger off a few times today as alignment activities commence. I'll (or designee) try to keep it damped throughout the day.
The switch values on the MEDM were consistent. They explicitly display the state of each switch and watchdog state. ETMY damping loops were not closed last night (05/22/12). The damping loops were left open for AIS measurements yesterday afternoon. The ETMY SUS damping loops have been left open for several nights since the in-chamber installation. The damping loops will be left closed overnight henceforth.
At 06:28 local time Tuesday 22 May, h2fw0 crashed and restarted itself. Unfortunately the ini and par files had changed since the last DAQ restart and therefore h2fw0's frames contained bad data. The whole H2 DAQ was restarted at 8am to resync the whole system. A solution to the out-of-sync-configuration is being installed. The cause of the original crash is still under investigation.
The ring section and hand brushing of the upper chamber was completed yesterday. The flooring was shifted to one side and and half the chamber bottom was brushed.
Attached are plots of dust counts > .5 microns.
Over the past few days we've relocked the reference cavity in the optics lab, coupled the transmitted light into a fiber optic cable, and shot it down to End-Y. This will be used to stabilize the ALS laser using a phase-locked loop, at least until the new H1 PSL has a serviceable FSS. For the reference cavity, the setup is the same as that put in place by Matt, Bram, and Szymon last fall. After a few days of loop tuning and optics tweaking (label your optics! and for crying out loud, don't label something 'HWP' on one side and 'QWP' on the other!), we settled on a UGF of 120kHz with about 40 deg of phase margin. The loop is pretty stable, but experiences an intermittent high-frequency oscillation that causes an audible buzzing in the EOM. We're not sure what this is coming from, maybe insufficient gain in the fast path (relative to the fast-fast EOM path). The visibility through the cavity is not great, only about 20% at the moment. We take 95% of the transmitted light from the cavity and couple that into a fiber optic. This coupling isn't that great either, only about 30%; the mode matching could use some work. From there, the fiber runs to the mass storage room, and connects to a spigot of the communications cable that goes down the arm. Four kilometers later it emerges in the VEA field rack, about ten meters from the ALS table. We're using the first connector, in the upper left corner of the fiber patch panel. The transmission from the optics lab down the arm is quite respectable, only about 5.7dB is lost. Better than 1.5dB/km! Here are some numbers: 41.6mW incident on the reference cavity 7.0 mW transmitted through the cavity 2.2 mW coupled into the fiber 0.6mW at End-Y One potentially worrisome thing is that the fiber coupler appears to scatter light back into the reference cavity, which causes fringe wrapping or some other junk on the RFPD. There's a bunch of noise in REFL_DC when the beam is aligned into the fiber coupler, and it goes away when you block the coupler with your hand. We may have to install a Faraday isolator on the transmitted beam to keep this from polluting the PLL. Another thing: does the reference cavity have some seismic isolation inside the vacuum can? Like, is it sitting on springs? When we hip-check the optics table there's a vertical mode at about 4Hz that gets rung up. Currently for laser-safety reasons the fiber optic is disconnected in the optics lab, we'll plug it in once the cabling at the endstation is worked out.
Gerardo and I started the long process of leak testing new conflat joints on the H1 input MC volume. Gerardo found a 6.1 x 10-7 torr*L/sec leak on HAM3 lower SW (1)12"x(3)4.5" feed-through (leak on 12" joint). Much more hunting in the next few days. Also, I accidentally shut of the instrument air to the safety valve on the YBM MTP and had to restart the MTP shortly after it began to spin down.
The latest SUS ETMY measurements indicate the M0 & R0 masses are fully free-swinging with nearly all of the resonances lining up with the QUAD model. The measurement from last night (05/21/12) is plotted with previous measurements of this QUAD with one from ITMY. The drive in the 0.1-4Hz band was increased by a factor of three for all DoFs on both masses. The result is a cleaner measurement in this band (compared to the 05/18/12 meas.) with a better SNR.
D. Cook, J. Oberling
We set our equipment back up and measured pitch and yaw of the ETMy this afternoon. The results are as follows:
As can be seen by these results, further adjustment is necessary to bring the ETMy pointing into spec.
When we went to BSC6 to check the viewport for the ALS green beam, we've quickly found out that the beam was not hitting the EY, not even the primary.
The beam was at least 4mm too high on the secondary (picture will be posted by Cheryl). That's a huge number.
Since there's no lens/curved mirror between the ALS table and the secondary of the TMS telescope, and since the distance between the top periscope mirror of the ALS table and the secondary on the TMS telescope is something like 3.5m roughly, we're talking about 1mrad-ish number if it is something on the ALS table, and much much more if it is something on the TMS.
Vincent assured me that the ISI was good.
Hugh looked at the dial gauges of the HEPI and told me that the changes since May/07 are all 0.1mm or less. That's over 3 or 4mm distance. That's nothing compared to what we're seeing.
There was no change in the TMS bias voltages since we "finalized" the alignment a week ago, and though the OSEM values showed some drift it's about 1000 counts maximum, and that doesn't sound that big. Nobody worked on the ALS table since the last alignment. Picomotor driver cable was disconnected last time we finished working on that.
At this point, there are three potential cause of this:
1. Wedge of the viewport
BSC6 high quality viewport was removed from BSC6 for cleaning after our "final" TMS alignment, and then installed again.
Though this is "no-wedge" viewport, the spec (E1100267) says "up to 5 arc minutes", which is 1/12 degrees or 1.45 mrad. Assuming the refractive index of n=1.45 and using a small incident angle approximation, the angle deviation caused by this viewport is approximately up to
1.45 mrad * (n-1) = 0.65 mrad.
If the viewport was rotated 180 degrees after cleaning, that will cause up to 1.3 mrad difference.
Since the distance from the viewport to the secondary along the optical path is roughly 3m, 1.3 mrad roughly corresponds to 4mm shift.
2. Bias of the PZT mirror on the ALS table
We've found that one of the four inputs for the PZT mirrors is 14 Volt for whatever reason. I'm quite certain that the offset was there when we aligned the TMS. Indeed, when I disconnected the input cable from the PZT driver, the beam was totally misaligned and didn't even come out of the ALS table.
We still don't know why there's such a stupid offset, but anyway it's not impossible (though not very likely) that this offset drifted over time. The iris is much closer to the PZT mirrors than to the TMS secondary, so a tiny change in the PZT mirror angle could lead to a big position change on the secondary.
3. TMS mirrors
It's not impossible that the TMS mirrors got bumped. Again this is not very likely, because there are only two relevant mirrors that are easy to bump, and it's kind of difficult to bump them to cause problem mostly in pitch only.
Whatever the cause of this is, we'd like to fix this by:
If possible at all we'd like to do this the first thing in the morning.
Bubba says that it was put back in rotated by 180 deg. He's sending somebody to rotate it back.
Picture showing the secondary telescope mirror and the ALS beam. The beam position is significantly above the center of the mirror, about 4mm, as measured on 5/22, but was well centered when TMS alignment was completed. Picture by Alberto.
