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• Minutes20210413

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

Participants: Satoshi Tanioka, Kenta Tanaka, Naoki Koyama, Chiaki Hirose, Kentaro Somiya, Kiwamu Izumi, Koji Nagano, Marc Eisenmann, Masayuki Nakano, Naoki Aritomi, Shoichi Oshino, Tomotada Akutsu, Yua Michimura

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 JGW-T2112769 (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]