Not much progress has been made toward understanding the ITM charge mystery of aLOG 29699 and earlier. I tried to get quad-specific charge information before the earthquake hit tonight, but I found the data had insufficient SNR at my excitation amplitude.

To measure effective bias voltage of an ITM, read /ligo/home/chris.whittle/Documents/ITM_CHARGE_README.txt, set appropriate excitation amplitude/frequency and run /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/Scripts/ESD_TM_charge.py as (for example)

python ESD_TM_charge.py -l -m -o ITMX

(further instructions in the readme).

To perform a swept sine measurement, set the bias voltage to your desired value, then open the DTT template at /ligo/home/chris.whittle/Documents/charge/itm_charge_sweep_sine. You will have to set an envelope for the excitation frequencies. Previously, /ligo/home/chris.whittle/Documents/charge/analyse_sweep.py was used to calibrate and re-plot this data (requires transfer functions and coherences from charge measurement and pcal measurement).