Lena/Oct 2016
Jump to navigation
Jump to search
October 2016
BACK/NEXT
10/03/2016
fMCG setup TODO
- Feedback system to keep the fields from "running away". Only the main XYZ fields need to be stabilized, the gradients don't change much day to day
- Reduce the polarimeter noise when misbalanced
Eliminating polarimeter noise when misbalanced
The existing current amplifier consists of two photodiodes connected in a way to add or subtract their photocurrents. The output of this passive circuit is connected to an SR570 current preamplifier.
I want to replace this circuit with something that can output both sum and difference, so that the common mode variations can be cancelled. Apparently a circuit that is supposed to do that has already been designed (see the link). The circuit has very little documentation and needs to be modified to increase the gain. We need 1-2 μA/V on the differential channel and 100-200 μA/V on the sum channel.