Evan, Elli
The auxiliary laser can now lock to the carrier (IM4 transmitted beam) on IOT2R using a NewFocus LB1005 servo controller. LB1005 settings are gain=5, PI corner=3kHz, LF gain limit=60dB.
A 1.8GHZ network analyzer is used as the local oscillator to set the frequency offset. We can sweep the frequency offset over 3.5MHz.
We measured the open loop transfer function (see attached plot). The UGF is at 15kHz with 70 degrees of phase margin.