Scraps of text for incorporation in the VIS Meeting Minutes

KAGRA/Subgroups/VIS/MeetingNAOJ

Type B (Mark)

Report for week of 1/14

• Etc
  • Hirata-san ordered three 41 mm spanners for adjusting the jacks under the top of the tanks.
  • Mirapro installed bellows on the -Y side of BS and the +Y side of SR2.
  • Simon got us an LED, a 2D QPD stage and a second 300x400 mm breadboard, which should be enough to do the SRM TILT OL. He's working on a few more items needed for the LEN OL.
  • Terada-san and Uchiyama-san placed height markers on the SR tank frames showing the BS height and the desired SR heights allowing for 1/300 gradient: SR2 BS+17 mm, SR3 BS+56 mm, and SRM BS+70 mm.

  • Terrence and Mark reworked the Type B Guardian code to simplify future maintenance, so that the scripts VIS_BS.py etc are now tiny stub files which call common code in TYPEB.py.

  • Mark, Terrence and Enzo updated all the Type B models and MEDM screens to add support for binary output to the stepper driver enable inputs, and Enzo ran cables from the front ends to the BIO adapters, and thence to the drivers. We tested the SRM setup but it doesn't yet work.
• BS
  • We installed the three new geophones originally prepared for SRM and then realized we'd made a serious mistake: the old wiring used adapters at both ends of the cable to compensate for the flipped preamps in the original geophones, and we forgot to take out the ones at the rack end. So two of the new ones appear to have been damaged and will have to be repaired. VIS has enough preamps to fix all the broken Type B geophones, but Type A will also need some more soon and there aren't enough in total, so we will have to repair them.
  • Hirata-san tried various things including turning the F0 FR carriage upside down to try to fix the jamming problem but it didn't seem to help. After advice from Takahashi-san and further debugging we discovered that we had a half-dead channel on the BS_GAS stepper driver, so we switched to a working channel, and that fixed things.
  • We recalibrated the F0 LVDT, this time measuring the height from the top down as we had been doing for the SRs. We also measured the range of the F0 FR in steps and millimeters and its effect on the keystone.
  • We tuned the IP for frequency and centered it in L, T and Y. We got 78 mHz.
• SRM
  • Hirata-san checked the F0 yaw stepper and it worked.
  • (CHECK!!) Hirata-san checked the channels on the SRM stepper drivers and found they all worked. However the F0 FR still didn't move, so he tried turning the carriage upside down, and that fixed it. So between the BS and SRM there were two independent causes of the same problem.
  • Fabian surveyed the height of the SRM relative to Terada-san's reference with the GAS filters at nominal height and found it was 3.5 mm low. This is well within the range of the jacks, so we will raise the entire suspension to fix it.
  • Fabian inspected the optic. It seems OK for dust, but there is still some residue left from removing the FC. We may try some more dabbing with acetone.
• SR2
  • Terrence and Enzo tested the third and last type of collimator (3500 mm) in the OL, but it had much too small a spot and dynamic range. We will standardize on 1.1 mm collimators for all OLs.
  • Fabian inspected the optic and found patterns that may be FC residue on both sides.
• SR3
  • Fabian and Ohishi-san tried using the Top Gun to remove dust found earlier by Hirose-san. The AR side came clean but the HR did not improve. Fabian wiped the security structure and LBB with Vectra10 wipes and ethanol.

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.