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Thu Sep 25 15:24:05 2008
MC_F VCO calibration
I calibrated the VCO driving the AOM for the AO path of the MC feedback.
I injected DC voltage to the VCO and measured the output frequency with the SR620.
The attached plot shows the relation between the input voltage to the VCO and the output frequency.
The coefficient is 1.75MHz/V. Since the AOM is double path, the actual actuation efficiency is 3.5MHz/V.
We can use this value for the calibration of the MC_F. However, the MC_F DAQ channel is sampling the VCO input voltage through a 10Hz high-pass filter.
This filter has to be taken into account to convert the MC_F counts to frequency.
I will measure the transfer function from the VCO input to the MC_F counts tomorrow.