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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: 12624     Entry time: Thu Nov 17 21:54:11 2016     In reply to: 12618     Reply to this: 12704
Author: Johannes 
Type: Update 
Category: General 
Subject: Achievable armloss measurement accuracy 

I don't like AS110 or AS55. Neither of them are designed for DC and so the DC readout chain is hokey. How about use an actual transimpedance PD with a 100-1000 Ohm resistor and a 3 mm diode? This would eliminate the alignment sensitivity and the drifts due to electronics and room lights.

This looks much better. I'm planning to take more data with the AS110 PD rather than AS55 when I get the chance, increase the averaging time, and also sigma filter the datapoints. That should get us to a good spot and cut down the uncertainty even further.

 

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