J. Kissel, A. Staley, S. Dwyer

While investigating the MICH OLTF on resonance, I noticed that the bounce mode notch in the oplev damping loop (ellip("BandStop",4,1.5,40,19.3,19.9)) was not the same as the M2_LOCKING_L notch FM10 (ellip("BandStop",4,1.5,40,17.7,17.9)). However, the roll modes were idenitcal (ellip("BandStop",4,3,40,25.7,26.4)). Using the oplev, I measured the bounce mode to be at 19.636 Hz and the roll mode to be at 26.211 Hz. So, I added another Bounce Roll M2 lock filter FM8 that matches the filter in the oplev damping. Using FM8 instead of FM10, seemed to have improved the MICH OLTF. However, later when we lost locked and tried re-acquiring DRMI the bounce mode rung up and we immediatly lost lock. I have reverted back to the original FM10, and we can now lock DRMI again. Unclear ...