= Simulation meeting 2021 Apr 27 17:00 =
Zoom2: https://zoom.us/j/6676627462

== Participants ==
Koyama, Hirose, June Gyu, Wang, Kokeyama, Eisenmann, Aso, Michimura

== Agenda ==
=== Updates from Projects ===
 * GUI
   * We are trying to install the angular misalignment and shortcut buttons are being developed for mirrors.
   * The sweep and transfer function feature is ready for commissioners (the sensitivity and misalignment functions are not).

 * Ifo model
   * Hirose is learning feedback signals of a Febry-Perot cavity with mirror maps in Finesse.

 * OMC model
   * June Gyu is trying yo build a theoretical model, and is perform some testing using Keiko's FPMI model.
   
 * Birefringence
   * Slide for updates [[ https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=12852|link]]
   * We have started studying the TWE map for the spare ETMX. Measurements at 0 and 180 degrees are missing. We are considering constructing maps for 0 and 180 degrees from measurements at other degrees (45, 90, 135, 225, 270 and 315 degrees).
   * We think that map(0)+map(90)=map(45)+map(135). We studied TWE maps for ITMs to check if this relation is correct. As ITMs are correctively polished using circular polarized beam, the sum of map(0) and map(90) should be close to zero. This should also work for the sum of map(45) and map(135). However, we found that the sum is not zero. This could be due to errors in the TWE map measurement. There are five DOFs: x, y, x-tilt, y-tilt and rotation. Each DOF can contribute to errors. We are going to scan these DOFs in the map to see if we can produce a smooth surface for the sum of maps. The scratches in the spare ETMX can help to relocate maps.