Max F., Daniel S.

The ALS common mode board S1102638 had the following modifications applied:
R70 -> 40.2 Ohm from 1.2K
C121 -> 1 uF from 33n
This gives us a common compensation with a pole at 1.35Hz and a zero at 4kHz. The DC gain is still 40dB, but the high frequency gain is now -30dB. This allowed us to remove the Pomona box filter.

The temperature control for the laser was shorted to the shield of the controller cable. After inserting a breakout board we were able to move the laser temperature. 

This in turn allowed us to engage the slow temperature integrator which made the fiber servo lock without tediously adjusting the temperature controller manually. The fast gain is now at 0dB, the common gain was set to -20dB. This gives us a unity gain frequency of about 7kHz. Increasing the gain by 3dB will excite a resonance around 270kHz.