40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Fri Feb 3 20:19:38 2012, rana, Update, SUS, Oplev QPD Sum Trends are suspicious a.png
    Reply  Mon Feb 6 11:07:21 2012, steve, Update, SUS, Oplev QPD Sum Trends are suspicious oplevsums.png
Message ID: 6253     Entry time: Fri Feb 3 20:19:38 2012     Reply to this: 6256
Author: rana 
Type: Update 
Category: SUS 
Subject: Oplev QPD Sum Trends are suspicious 

The attached trend shows a problem with the QPD sums.

Why are ETMX and ITMX so much lower than ETMY and ITMY? Are the laser's dying? Or is it the gain inside the QPD? Or the reflectivity of the coatings?

Steve - please check on Monday the laser powers and the ETM/ITM reflectivity for HeNe lasers. Maybe we have to increase the transimpedance gain in the heads.

Attachment 1: a.png  18 kB  | Hide | Hide all
a.png
ELOG V3.1.3-