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| ==== Report for week of 11/19 ==== * BS * Fabian did some debugging on the BS and found that the calibration for the F0 LVDT was off due to an Excel error, and that the sag wasn't quite the 7 mm originally observed, but still enough to cause the suspension to touch down. Enzo tried applying LVDT actuation at the GAS filters and got it to lift off far enough to get sensible TFs, but the required BF offset was enough to put the IM OSEMs at the very edge of their usable range, so this is not a good long-term solution. We can probably raise the F0 keystone during the vent by removing mass and/or installing an auxiliary spring, which will then allow us to return the BF keystone to nominal height. * While working on the BS, Enzo noticed that one of the stepper drivers was not responding. It turned out to be water damaged from the rain issues earlier in the year. Enzo and Fujii-kun opened the rest of the BS chassises on the second floor but they seem to be OK. Tanaka-san had made a third driver chassis as a spare, so we reserved that and will install it in the week of 12/10. * SRM * The SRM-W optic arrived and we installed it in place of the SRM-M in the metal mass, taking care to use 1.4 mm shims as recommended by Hirose-san. The weight of the new assembly was within 1 g of the old and did not disturb the height of the payload. There was a very small change in pitch which we corrected with the IM picos. * We installed the shelf for the OL receiver. * We added the arc weights and geophones and went through several rounds of improving the centering of the IP and then realigning the security structure back to vertical. * We calibrated the F0 LVDT, and checked the F0 and IP actuation signs. * We adjusted the SF trim masses to set the SF pitch and roll, did an inventory of the trim mass and set the damper gap. * We did a final alignment of the whole chain and left the suspension ready for TFs during the f2f week. There is only a few hours of work left before we can install and we hope to do that on Monday 12/10. * SR2 * Enzo replaced the geophones and cables that had been borrowed for calibration and did several rounds of optimization of the IP frequency. He got as low as 46 mHz but with poor Q and so backed off a bit to 55 mHz and may back off a tiny bit more. * I derived updated IP matrices for the BS and SR, with more precise geometry data provided by Hirata-san, and published them as T1707205 and T1807663. * I created a CENTERING screen for the IP, with large panel meters for the LVDT signals and the derived L, T and Y signals. * Enzo confirmed that the fancy stepper control screen created by Shoda-san worked. * We installed a modified LPCD as IM-V for testing. * SR3 * We moved HPCDs from BS and SR2 to replace the ones that had been stolen from SR3, so as to create a working suspension with an OL for Kozu-kun. ==== To-Do Lists, Schedule ==== * [[KAGRA/Subgroups/VIS/TypeB/ToDoBS]] * [[KAGRA/Subgroups/VIS/TypeB/ToDoSR]] * [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7779|JGW-L1807779 Type B Schedule (SR)]] |
==== Report for the week of 3/11 ==== * Fabian helped Fujii-kun with the PRM most of the week. Hirata-san also helped at various times. * Fabian monitored the SRM yaw drift. It gradually reversed but so far remained small. We will try resetting it to zero with the pico and see if the trend changes. * Mark and Hirata-san debugged the BS: * We inspected the payload section and quickly found the problem: two RM EQ stops were touching, on the +L (-X,+Y) side at the top. This was probably because the stops had been adjusted with the IP unlocked and sitting a few mm to -L, whereas now we have the DCCTRL running and have been locking the IP at the LVDT zero. We drove the IP to L=+1.5 mm as a near-worst case, and backed off all the stops to give several mm of margin. Then we zeroed the IP pitch, roll and yaw with the picos. * We also opened the top of the BS and confirmed that the mechanical zero defined by the locking mechanism agreed with the LVDT zero. It was very close in L and T, but -728 µrad in Y, driven mostly by a -805 µm offset in H3. That much is probably not a dumb error but just a difference in technique among the three people using calipers to take data for the calibration. * We then prepared the BS for close-up: * We wiped and inspected the O-ring for the lid and replaced the lid. * We wiped all accessible surfaces in the lower half of the tank, rescued some dropped items (some PEEK tube and a small nut) and un-immobilized the LBB. * After all the above, the OL was a bit off-center but still on the QPD, and Nagano-san fairly quickly recovered the original alignment. |
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| * Terrence rebuilt the BS TILT OL according to a new layout suggested by Simon, which avoids scrambling the pitch/yaw at the first steering mirror and greatly reduces the amount of diagonalization required. He started on the LEN OL, but unfortunately the QPD stage fell and bent the brackets holding two of the micrometers. It's useable but we haven't installed it yet. * Terrence noticed some anomalous cross coupling on the SR2 (but not the SR3) and we investigated. * We suspected it might be an odd position of the beam spot on the optic, so we took pictures through the camera and LED viewports of SR3, and opened the SR2 tank and used a white target, but the beam spots were in very similar positions - close to central vertically and about 3 cm to the left of center horizontally. * We suspected it might be something touching at the IRM (because the IM OSEM TFs were fine), so we checked using a stick mirror with the IP centered, but all EQ stops were well backed off. * We suspected it might be a ghost beam from the LEN/TILT beamsplitter (and one was clearly visible on the SR2 TILT QPD) so Terrence set up a beam block, which improved things slightly but not completely. |
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| ==== Plan for week of 12/3 ==== * f2f Meeting at NAOJ - no Kamioka work. ==== Plan for week of 12/10 ==== * Crane SRM into tank. * Install new F0 yaw mechanisms on SRs. * Remove First Contact from SRM, unlock and realign. * Move SRM in-air cables over. |
* Finally Terrence discovered that the problem was mainly uneven sensitivities of the QPD quadrants, and devised a new calibration procedure which allowed for it. Later we discovered that one of the 3 dB gain stages on the whitening filter was engaged, even though the switch on the BIO Config card was not. It mysteriously came good after we removed and replugged the BIO Config card. * Enzo and Terrence did a health check of the SRM and it was fine except for some apparent electrical noise around 240 Hz. They put in a low-pass filter to get rid of it for now. ==== Plan for week of 3/18 ==== * Mark, Fabian, Terrence at Kamioka full week. * More OL stuff. * SRM OL setup. * Recalibration of all OLs per new procedure. * Improve mounting of BS OL RX breadboard. * Reinstall BS LEN OL. * SRM controls and Guardian. * Reset SRM yaw and continue monitoring yaw drift. * Length/pitch decoupling. * Assist with pump down. * Work on Type B paper. * Tidy up. * Throw out foil and other garbage. * Gather and clean tools. * Gather and organize unused parts and fasteners. * Pull out unused cables in cable tray near SR3. * Return all unused cables to tent. * Tidy up cables in rear of SR2 rack. ==== Vacation/Travel Info ==== * Enzo at JPS then final vacation, 3/13-29 * Terrence's last day, 3/29. |
Scraps of text for incorporation in the VIS Meeting Minutes
KAGRA/Subgroups/VIS/MeetingNAOJ
Type B (Mark)
Report for the week of 3/11
- Fabian helped Fujii-kun with the PRM most of the week. Hirata-san also helped at various times.
- Fabian monitored the SRM yaw drift. It gradually reversed but so far remained small. We will try resetting it to zero with the pico and see if the trend changes.
- Mark and Hirata-san debugged the BS:
- We inspected the payload section and quickly found the problem: two RM EQ stops were touching, on the +L (-X,+Y) side at the top. This was probably because the stops had been adjusted with the IP unlocked and sitting a few mm to -L, whereas now we have the DCCTRL running and have been locking the IP at the LVDT zero. We drove the IP to L=+1.5 mm as a near-worst case, and backed off all the stops to give several mm of margin. Then we zeroed the IP pitch, roll and yaw with the picos.
- We also opened the top of the BS and confirmed that the mechanical zero defined by the locking mechanism agreed with the LVDT zero. It was very close in L and T, but -728 µrad in Y, driven mostly by a -805 µm offset in H3. That much is probably not a dumb error but just a difference in technique among the three people using calipers to take data for the calibration.
- We then prepared the BS for close-up:
- We wiped and inspected the O-ring for the lid and replaced the lid.
- We wiped all accessible surfaces in the lower half of the tank, rescued some dropped items (some PEEK tube and a small nut) and un-immobilized the LBB.
- After all the above, the OL was a bit off-center but still on the QPD, and Nagano-san fairly quickly recovered the original alignment.
- Terrence rebuilt the BS TILT OL according to a new layout suggested by Simon, which avoids scrambling the pitch/yaw at the first steering mirror and greatly reduces the amount of diagonalization required. He started on the LEN OL, but unfortunately the QPD stage fell and bent the brackets holding two of the micrometers. It's useable but we haven't installed it yet.
- Terrence noticed some anomalous cross coupling on the SR2 (but not the SR3) and we investigated.
- We suspected it might be an odd position of the beam spot on the optic, so we took pictures through the camera and LED viewports of SR3, and opened the SR2 tank and used a white target, but the beam spots were in very similar positions - close to central vertically and about 3 cm to the left of center horizontally.
- We suspected it might be something touching at the IRM (because the IM OSEM TFs were fine), so we checked using a stick mirror with the IP centered, but all EQ stops were well backed off.
- We suspected it might be a ghost beam from the LEN/TILT beamsplitter (and one was clearly visible on the SR2 TILT QPD) so Terrence set up a beam block, which improved things slightly but not completely.
- Finally Terrence discovered that the problem was mainly uneven sensitivities of the QPD quadrants, and devised a new calibration procedure which allowed for it. Later we discovered that one of the 3 dB gain stages on the whitening filter was engaged, even though the switch on the BIO Config card was not. It mysteriously came good after we removed and replugged the BIO Config card.
- Enzo and Terrence did a health check of the SRM and it was fine except for some apparent electrical noise around 240 Hz. They put in a low-pass filter to get rid of it for now.
Plan for week of 3/18
- Mark, Fabian, Terrence at Kamioka full week.
- More OL stuff.
- SRM OL setup.
- Recalibration of all OLs per new procedure.
- Improve mounting of BS OL RX breadboard.
- Reinstall BS LEN OL.
- SRM controls and Guardian.
- Reset SRM yaw and continue monitoring yaw drift.
- Length/pitch decoupling.
- Assist with pump down.
- Work on Type B paper.
- Tidy up.
- Throw out foil and other garbage.
- Gather and clean tools.
- Gather and organize unused parts and fasteners.
- Pull out unused cables in cable tray near SR3.
- Return all unused cables to tent.
- Tidy up cables in rear of SR2 rack.
Vacation/Travel Info
- Enzo at JPS then final vacation, 3/13-29
- Terrence's last day, 3/29.