= In-vac PD/QPD layout meeting 2024/12/23 =
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.
  * Enclosure size for RF QPDs were different. Needs to be updated. RF QPD enclosure size is in [[https://dcc.ligo.org/LIGO-D1102002/public|LIGO-D1102002]].
  * Need to include OMC REFL RF QPDs as well.
  * In our case, we don't need to care about the Gouy phase separation between steering mirrors
 * Beam height
  * RF QPD height is 4 inch, but the beam height in the OMC chamber is 210 mm.
   * See [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=9819|JGW-D1909819]]
  * Put a periscope to lower the beam height?
 * Put optics on a breadboard to make maintenance/test easier (make it easier to remove and re-install OSTM)
  * Do we also need to have QPDs on the breadboard or not?
  * If QPDs are on the breadboard, we also have to remove the cables for QPDs when moving the breadboard.
 * Steering mirrors for RF QPDs: One PZT and one picomotor for QPD centering needed

 * '''A/I'''
  * Update the layout to include OMC REFL RF QPDs [Huali]
  * Send Huali the part numbers for in-vac steering mirror mounts [Yuta]
   * 2-inch ones in OMC chamber are [[https://jp.optosigma.com/en_jp/vmhg-50.8.html|Sigma-Koki VMHG-50.8]]. See, also [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3916|JGW-D1503916]]
  * Update [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=16178|JGW-T2416178]]. OMC REFL QPD should be RF, not DC. [Yuta]
   * DONE on Jan 7, 2025
 * Next meeting: in the week of Jan 20, 2025
  * Decided to Jan 23, 2025 14:00-15:00 (JST)