40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  PSL  Not logged in ELOG logo
Message ID: 1312     Entry time: Fri Aug 23 19:00:13 2013
Author: Evan 
Type: DailyProgress 
Category: RefCav 
Subject: No more reflection overlap 

 [Tara, Evan]

Tara and I opened the CTN vacuum can this afternoon. Previously, the reflection from the vacuum window was overlapping with the reflection from the south refca, so Tara repositioned the seismic isolation stack in order to get rid of this overlap. We have now realigned into the two refcavs, and neither show any reflection overlap. The attached picture shows the two reflections at the PBS pickoff for the RFPD path for the south cavity. The large spot is the refcav reflection. Slightly to the left of it you can kind of make out a much smaller spot, which is the reflection from the vacuum window.

For the north cavity, the refcav reflection is currently clipping on the QWP nearest to the vacuum can, while the vacuum window reflection makes it through the QWP and onto the RFPD path. So evidently there's no overlap here either.

We also took some measurements of the impulse response of the seismic isolation stack, but that will be covered in a subsequent elog post.

Attachment 1: rr.jpg  157 kB  | Hide | Hide all
ELOG V3.1.3-