Question: Regarding dark port DARM control signal.

I see that the power in the dark port goes below zero at the dark port in the given plot, however I am not getting any negative values? is it just an offset or am I missing something?

2 comments on “Question: Regarding dark port DARM control signal.

  1. Hi Sagar,

    You’re right in that this is an offset, as this is the control signal, not the measured field – it’s impossible to obtain negative light power out of the detector! Hopefully you can see why this offset is present; consider if there was no offset, and the DARM control signal zero sat at the minimum of that dip. How would you correct for a slight change in DARM?

    1. To get the control signal I would subtract the value I had originally, so that I can implement PID or at least the proportional part of the control. I am guessing that is what’s happening here.

Leave a Reply