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Entry  Thu Sep 29 20:21:29 2016, Johannes, Update, General, YARM loss measurement 
    Reply  Mon Oct 3 21:24:02 2016, Johannes, Update, General, XARM loss measurement ReflectionLoss.pdf
       Reply  Tue Oct 4 22:18:24 2016, Johannes, Update, General, X/YARM loss measurement anomalousData.png
          Reply  Wed Oct 5 19:10:04 2016, gautam, Update, General, Arm loss measurement review 
             Reply  Mon Nov 14 19:15:57 2016, Johannes, Update, General, Achievable armloss measurement accuracy 
                Reply  Tue Nov 15 20:35:19 2016, Johannes, Update, General, Achievable armloss measurement accuracy 
                   Reply  Thu Nov 17 21:54:11 2016, Johannes, Update, General, Achievable armloss measurement accuracy 
                      Reply  Thu Jan 12 02:45:53 2017, Johannes, Update, General, Next armloss steps ass_illustration.pdf
                         Reply  Fri Jan 13 08:54:32 2017, Johannes, Update, General, DC PD installed ASDCPD_up.jpgASDCPD_down.jpgscrambled_osci.jpg
Message ID: 12528     Entry time: Mon Oct 3 21:24:02 2016     In reply to: 12524     Reply to this: 12531
Author: Johannes 
Type: Update 
Category: General 
Subject: XARM loss measurement 

[gautam, johannes]

I started a script on Friday night to collect some data for a reflection armloss measurement of the XARM. Unfortunately there seemed to have been a hickup in some data transfer and some errors were produced, so we couldn't really trust the numbers.

Instead, we took a series of manual measurements today and made sure the interferometer is well behaved during the averaging process. I wrote up the math behind the measurement in the attached pdf.

The numbers we used for the calculations are the following:

While we average about 50 ppm +/-15 ppm for the XARM loss with a handful of samples, in a few instances the calculations actually yielded negative numbers, so there's a flaw in the way I'm collecting the data. There seems to be a ~3% drift in the signal level on the PO port on the order of minutes that does not show in the modecleaner transmission. The signals are somewhat small so we're closing the shutter over night to see if it could be an offset and will investigate further tomorrow. I went back and checked my data for the YARM, but that doesn't seem to be affected by it.

Attachment 1: ReflectionLoss.pdf  125 kB  Uploaded Mon Oct 3 19:24:44 2016  | Hide | Hide all
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