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• Minutes20250624

In-vac PD/QPD layout meeting 2025/06/24

Time: June 24, 2025 14:00-14:40

Participants: Huali Chen, Ryan Yang, Yoichi Aso, Yuta Michimura

Zoom meeting

Minutes

• REFL (Ryan)
  • Updated the in-air path so that the paths will be parallel to the grid of M6 screw holes of the optical table

  • https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=16702

  • TBD things:
    • Beam diverter need to be designed, and to be put in the in-vac layout.
    • Start designing the vacuum tank (consult with VAC people)
    • Beam dump locations
• AS (Ryan)
  • Made all 210 mm height optics to be 2 inch dia., 4 inch height optics to be 1 inch dia.

  • https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=16705

  • TBD things:
    • ORM1 post height need to be adjusted to match the height
    • In-vac periscopes, fast beam shutter, diverter for AS RF need to be designed and placed
    • Periscopes need to change the height from 210 mm to 4 inch - (base plate height = 15 mm?)
    • Base plate for RF QPDs
    • Beam dump locations
  • In-vac periscope references:

    • ALIGO IO L1 IN VACUUM INPUT PERISCOPE ASSEMBLY https://dcc.ligo.org/LIGO-D1002350

    • ISC TransMon Periscope Lens Bracket https://dcc.ligo.org/LIGO-D1003296/public

    • ALIGO IO H1 MC REFL PERISCOPE https://dcc.ligo.org/LIGO-D1201410

  • NOTE: OSTM wedge
    • Thicker side is OMC side in the original design

    • Thinner side is OMC side as installed currently https://klog.icrr.u-tokyo.ac.jp/osl/?r=30159

    • Black lines in https://gwdoc.icrr.u-tokyo.ac.jp/DocDB/0167/D2516705/001/OMC_chamber_20250530.png is for thinner side being OMC side

• POP (Yuta)

  • See last two pages: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=16178

  • GreenX path: Only in-air.
  • POP path: In-vac and in-air. Two RF PDs, two RF QPDs each for in-vac and in-air. Diverter for in-vac. Cameras and DC PDs for in-air.
  • Forward POP path: In-air only.

• A/I

  • Consult with VAC people to start designing REFL PD tank [Yuta]
  • Start in-vac periscope design [Ryan]
    • Try to use Opto-Sigma VMHG-50.8 instead of Siskiyou LIGO mirror mounts
  • Some comments from Akutsu-san and Sato-san on June 26
    • New optics for RF QPDs should be put on a single plate (or two plates). OMC table might be shaved so that the height does not change.
    • Beam dumps need to be placed for RF QPD reflections and lens reflections
    • Need to know the rough idea of (new) locations for OFI, beam shutter, diverter, periscopes, base plate for RF QPD paths, and beam dumps
      • By the end of this year
      • Weight is critical for OMC vibration isolation table design
    • Also need information on cables. Cables are heavy too.
      • Cables for RF QPDs, picomotors, PZTs, beam shutter, beam diverter
• Next meeting: TBD