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==== Report for the week of 3/4 ====
 * On Monday, Mark helped Aso-san with PR3, and Monday, Tuesday and Wednesday, Fabian helped Fujii-kun with PRM.
 * Mark and Terrence attempted to offload some BS IM/IRM yaw adjustments that had been done by Enomoto-san last Friday. They rezeroed the OL and then opened the tank lid and did a compensating adjustment to the F0 yaw stepper, then undid the IM/IRM yaw with the pico. However this did not have the desired effect, probably because the buoyancy correction had not been cancelled when Enomoto-san was working and the BF keystone was very high, with the IM-V OSEMs way too far in and possibly touching. We did our best to back out all the adjustments but the roll TFs were still messy and there were signs that the IM was not free in yaw (the IM/IRM Y varied oppositely to IP Y, indicating that the IMR was free and the IM wasn't). We ended up deciding to have Mirapro remove the ducts on the ±X sides of the tank so we could go in and inspect.
 * Terrence tuned the SR3 LEN OL to be free of yaw cross-coupling.
 * Terrence and Enzo did a full set of filters and a Guardian for SR2 and SR3.
 * Terrence did health checks on SR2 and SR3.
 * Enzo measured mode Qs on SR2.
==== Report for the week of 3/11 ====
 * Fabian mostly helped Fujii-kun with the PRM.
 * 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 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.
 * 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 and diagonalization procedure which allowed for it.
 * 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 notch filter to get rid of it for now.
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 * Install/test hardware watchdogs.

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 mostly helped Fujii-kun with the PRM.
  • 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 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.
  • 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 and diagonalization procedure which allowed for it.
  • 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 notch filter to get rid of it for now.

Plan for week of 3/11

  • Mark at Kamioka full week.
  • Enzo at Kamioka Mon, Tue, then JPS.
  • Hirata-san at Kamioka from Monday lunchtime through Friday.
  • Fix BS.
  • Final test of stepper remote enable system (someone in cleanroom checks the lights go on/off).
  • Continue monitoring SRM yaw drift.
  • More mode Q measurements.
  • Work on Type B paper.

Vacation/Travel Info

  • Enzo at JPS then final vacation, 3/13-29
  • Terrence's last day, 3/29.

KAGRA/Subgroups/VIS/TypeB/Minutes (last edited 2022-06-24 12:23:36 by fabian.arellano)