Scraps of text for incorporation in the VIS Meeting Minutes

KAGRA/Subgroups/VIS/MeetingNAOJ

Type B (Mark)

Report for week of 1/14

• Etc
• BS
• SR2
  • Hirata-san helped with installing the obelisk on the LBB, and added counterweights to get the LBB level and at the right height for the first rough alignment. However the springs were still at or near the top stops, so he later pulled down the LBB with excess mass, locked the blades at the bottom of their range and reset the LBB rods and damping magnet ring, aiming off by 10 mm so that it would be correct when the LBB was allowed to rise. However he left it pressed down for now so that Hirose-san could apply FC. Early next week he will release it and do the final ballasting.
• SR3
  • Enzo installed IM damping filters.
  • Mark installed a BIO Converter for the stepper remote enable (which will eventually also be used for the WD).
  • Fabian researched buoyancy compensation and pre-applied as much as possible. The total compensation needed is 0.19 mm for F0, 0.48 mm for SF and 0.46 mm for BF, total 1.23 mm.
• SRM
  • Mirapro helped us with the camera viewport issue by giving us a gasket of the same type but a different brand from their stock, which snapped easily into place. We then installed the viewport on the tank.
  • Fabian calibrated the F0 FR.

Report for week of 1/21

BS (top priority)

• Last Friday: We tuned the IP to have a lower frequency. At the begginig we measured 78mHz.
• Last Friday: With Lucia, we centered the IP and diagonalized the IP. After this process we measured a resonant frequency of 40mHz. We closed the position control loop for the IP.
• We checked during the weekend and the suspension was not in a healthy state. We checked the IM horizontal OSEM coil driver, and there were some cables in the wrong connectors. (Test in instead of ...)
• The adapter for the cable of the F0 fishing rod was not healtly. We fixed it but it might be good to replace it.
• The commissioning team steered the BS IM to reach the Y-end and then Terrence centered the oplev with this orientation (more than once).
• Fujii-san and Enzo fixed old BS geophones by replacing the Preamp.
• We replaced the Geophones for the recently fixed ones.
• Hirata-san and Fabian secured trim masses to the keystone.
• We installed GAS Filters and IM control loops
• Currently Terrence and Enzo are centering the IP using the horizontal fishing rods.

SR2 (priority 2)

• We measured the optic height. According to the measurement it was 0.1 mm off. However, the systematic error is likely larger (laser level, position of reference). Apparently, the RM has a small amount of roll but this should be investigated further. It might just be systemaric error of the measurement. The roll of IM was adjusted to a value close to zero before the measurement.
• We calibrated the F0 fishing rod stepper motor.
• We raised suspension using the jacks. We rotated the jacks by 180 degrees roughly.Compensation has to happen with F0, F1 and BF.
• We removed tape, writing etc on PI and PI items.
• We removed the trim mass.
• Terrence restored the OPLEV to the original layout with an 1.1 m collimator and calibrated the tilt sensing QPD. Expect a pitch range of +/-223 urad and a yaw range of +\-322 urad.
• We centered the IP by using the jacks. L and T came good but there is a large yaw ~ 5 mrad.

• We diagonalized the IP actuation matrix. We closed the position control loop for the IP. (This has not happened yet).

• We installed GAS Filters and IM control loops. (This has not happened yet).

SR3 (priority 2)

• The bouyancy correction was calculated. It's 1.3 mm.
• The strategy is rasing the suspension by 1.3 mm and then moving the keystone by 1.3 mm with the fishing rod so the alignment team can work.
• We measured the optic height using Terada-san's reference. The SR2 optic was at the correct height.
• We raised suspension using the jacks by an amount calculated with the jack thread: M42 with 2 mm special thread. We rotated the jacks by approximately 180 degrees.
• Terrence reinstalled OL LED, collimator (1.1 m) and relaigned the OL. Both QPDs were calibrated and expect a range of L: $\pm$332 $\mu m$, P: $\pm$217 $\mu rad$ and Y: $\pm$306 $\mu rad$.
• OPLEV diagonalization hasn't been done but we expect minimal coupling due to the OPLEV. Strange couplings (due to the geometry of TM) are expected but no conclusive results yet.
• We removed tape, writing etc on PI and PI items.
• We calibrated the F0 FR against the readout of the F0 LVDT. We removed the trim masses (110 g). Then we moved the F0 keystone by 1.3 mm downwards.
• We centered the IP by adjusting the height of the jacks by small amounts. Longitudinal and Transverse positions came good but there was a large yaw (-5 mrad) when the stepper motors were in mid-range. Currently the yaw is -1 mrad and the steppers are using 80% of their range already.
• The F0 yaw stepper should, in principle, give plus minus 125 mrad range. We should check with a measurement how good this range is (e.g. cables being pulled, components touching, etc.) We can use the vertical laser level as an oplev or the main interferometer beam

• The front of the optic was cleaned by Hirose-san with Hirata-san's help. Hirata-san and Fujii-kun released the optic. The IP is still locked.

• F1 fishing rod is not responsive. We have to check the cables.

• We diagonalized the IP actuation matrix. We closed the position control loop for the IP. (This has not happened yet).

• We installed GAS Filters and IM control loops. (This has not happened yet).

Talk about problems turning on and off control systems (Terrence and Enzo) From Terrence: Since the PI controller was implemented, the controller keeps accumulator displacements error and converts this error to the output. One problem arose from the mismatch of the control system and the actual hardware. Because the controller output could have a much larger value than the number of counts that can be input to the coil actuators (e.g. the controller says we should input 60000 counts to the actuators but the hardware limits the number of counts), the controller will not function as designed. As a result, the PI would shift to one side (due to insufficient driving force) while the voices coils became saturated at maximum output. Additionally, because the controller is still functioning, the integrator keeps accumulating error and hence the output of the controller keeps increasing but the object is actually stuck. This makes the IP very very unstable when the actuators are saturated.

Give status of oplevs (Terrence and Enzo).

SRM (low priority)

• Hirose-san, Hirata-san and Fujji-san fixed the RM to the SS and removed the SRM for cleaning.
• Terrence installed the optical breadboards on the shelfs for the OPLEV; and, assembled the beamsplitter assembly, lens assembly and the folding mirror assembly. The LED box, collimator and the fibre connected were placed on the lower breadboard and the others are placed on the upper one. Still missing steering mirror to complete a tilt setup and a lens for the length OPLEV.

Postponed

• Raise suspension 3.5 mm on jacks.
• Check/improve payload alignment and IM OSEMs. Recheck optic pitch with OL as needed.\
• Adjust F0 keystone trim to give desired height and secure weights in place.
• Install geophones and arc weights.
• Center and tune IP.
• Hook LBB and add just enough ballast to have it bouncing.
• Wipe inside tank with Vectra-Alpha wipes and IPA.
• Set up TILT OL.