Matt, Hang

We wrote some codes to optimize a2l coupling coeffecients. The script will measure omc dcpd's response to injected angular dither, and do a linear fit (for I and Q separately) of this response as a function of a2l gain. With a proper rotation of the I-Q plane s.t. the rotated Q' stays as a constant, the minimum of the response will be at the zero of the rotated I'. 

We ran the script for ITMX, ETMX, and ETMY. Results are shown in the attachments. The errorbars were underestimated because the raw data might be correlated if the sampling frequency was not low enough, thus we just plotted them as a reference but no minimization of chi-sq in the fit. 

Based on them, we did the following changes:

H1:SUS-ITMX_L2_DRIVEALIGN_P2L_GAIN: 2.300 -> 1.947
H1:SUS-ITMX_L2_DRIVEALIGN_Y2L_GAIN: 1.350 -> 0.632

H1:SUS-ETMX_L2_DRIVEALIGN_P2L_GAIN: 1.100 -> 0.927
H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_GAIN: 1.370 -> 0.927

H1:SUS-ETMY_L2_DRIVEALIGN_P2L_GAIN: -0.200 -> 0.000
H1:SUS-ETMY_L2_DRIVEALIGN_Y2L_GAIN: -0.600 -> -0.700