In-vac PD/QPD layout meeting 2025/01/23

Time: Nov 20, 2024 10:00-10:30

Participants: Ray-Kuang Lee, Huali Chen, Yoichi Aso, Yuta Michimura

Zoom meeting

Minutes

• Huali showed the layout idea for AS RF and OMC REFL, with squeezing injection optics.

  • Add periscope to reduce the height approx. 210 mm -> 4 inch) and use smaller pedestals (footprint for 210-mm-high mirror is dia. 78 mm; see JGW-D1503916).

  • Add existing AS RF in-air and OMC REFL in-air paths in the layout and see if all of them can co-exist.
  • Try to simplify the layout by removing some of the steering mirrors to avoid scattered light from steering mirrors as much as possible.
  • We can also add some extension plate to extend the table
  • Do we really need two steering mirrors (one for piezo and one for picomotor) before each QPD?
    • We can also mount disc+piezo+mirror on a picomotor mirror mount to realize both actuation with one steering mirror

• A/I

  • Check if OMC REFL RF QPD in-air is necessary [Michimura]

    • May be not. Beacon WFS is used only after locking OMC (before handing over to DC readout). LIGO is also not using OMC REFL in-air (they only have in-vac OMC REFL DC QPDs; LIGO-T1000264)

  • Check what LIGO is doing for RF QPD centering (only picomotors?) [Michimura]

    • REFL WFS: Two tip-tilts before WFS sled, two picomotor mirrors on WFS sled LIGO-D1000313

    • AS WFS: Two tip-tilts (OM1, OM2) before WFS sled, two picomotor mirrors on WFS sled LIGO-D1000342 LIGO-T1200410

  • Upload the slides to JGWdoc, and present the current status at the ISC meeting on Jan 27 from 15:00 JST [Huali]
• Next meeting: TBD