ISC Meeting on 2020/04/13 13:00 - 15:00

Participants:

Zoom meeting: https://zoom.us/j/6676627462

Your time zone: https://www.timeanddate.com/worldclock/fixedtime.html?iso=20210413T0400

Next meeting

TBD

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Minutes

Agenda

Summary of interferometer alignment in O3GK and RSE commissioning JGW-T2112594 (Michimura)
Discussion on how to proceed for O4
- Are we going to remove ISS setup at IMMT1T?
- Any upgrades necessary for IMC ASC?
- Can we automate the beam centering with Tcams for reproducibility?
- Any thoughts on why PRMI alignment has to be done before Yarm alignment?
- Are there better ways for daily alignment?
- What are the steps necessary for engaging WFS/QPD loops in O4?
Other recent topics related to ISC
- Fiber noise cancellation improvement plans for ALS [Tanioka]
- Non-polarized beam splitter https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=10506 [Michimura]
  - IMC REFL: Thorlabs BSW11 are used (Ts=~40%)
  - IMC TRANS: Probably Thorlabs BSW11 are used
  - REFL: Note that p-pol is coming out from the chamber. Newport 10Q20HBS.33S (for s-pol) are used. Thin film polarizers are also used and there seems to be a confusion.
  - POP: Newport 10Q20HBS.33S (for s-pol) is used. S-pol/P-pol power ratio can be confused with this BS.
  - POS: No BS placed.
  - AS: p-pol is coming out from the chamber. We agreed to use HWP to make them s-pol and to use Newport 10Q20HBS.33S (for s-pol). But this solution might be confusing.
  - Planning to order non-polarized BS soon.
- In-vac steering mirrors: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=12592 [Michimura]
  - For some steering mirrors, p-pol beam
    - STM1, STM2, POM1, POM2 around IFI (PYD-20 is used)
    - steering mirrors after OFI
    - PYD-20 has a transmission
      - T < 70ppm at 0 deg for s-pol (measured)
      - T < 25ppm at 30 deg for s-pol (measured)
      - T < 5ppm at 45 deg for s-pol (measured)
      - T ~ 1000pppm at 45 deg for p-pol (specsheet)
    - Also, specs of POP_POM and POS_POM for IR p-pol needs to be investigated
- Optical table cover for TRX/TRY and IMC REFL/IMC TRANS: Review page [Michimura]