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Lena/Oct 2016: Difference between revisions
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Low-frequency gain of the differential polarimeter seems to be larger than the of SR570. It's unclear if it's a feature or a bug or a poor connection.
== 10/24/2016 ==
=== Testing the difference/sum mode ===
Tested how the difference only mode compares to the difference/sum mode in terms of field sensitivity. Both measurements were taken with the same polarimeter board.
When the polarimeter is balanced, the probe sensitivity in both modes is the same. When the polarimeter is misaligned, the noise in 0-10 Hz band increases for the difference-only polarimeter, but not for the difference/sum polarimeter. In overall, the noise floor for difference/sum polarimeter is really good and the probe noise level drops rapidly in 0-0.5 Hz band.
=== Small polarimeter imbalance ===
Difference between channels' light powers is 1.4 μW.
[[https://wiki.physics.wisc.edu/zhivun/index.php/File:20161024SmallImbalance.png]]
=== Large polarimeter imbalance ===
Difference between channels' light powers is 6 μW.
[[https://wiki.physics.wisc.edu/zhivun/index.php/File:20161024LargeImbalance.png]]
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