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Entry  Mon Dec 3 17:04:12 2012, Ayaka, Update, PSL, PMC calibration for MC_F calibration DSC_4955.JPGsweep_PZTdriver.pngPMC_PZT_FSR.pdftrans_fit.pngPMC-PZTcal_121203.zip
    Reply  Tue Dec 4 01:43:37 2012, rana, Update, PSL, PMC calibration for MC_F calibration 
    Reply  Tue Dec 4 11:30:36 2012, Zach, Update, PSL, PMC calibration for MC_F calibration 
       Reply  Thu Dec 13 17:24:53 2012, Ayaka, Update, PSL, PMC calibration for MC_F calibration 6x
Message ID: 7782     Entry time: Tue Dec 4 11:30:36 2012     In reply to: 7778     Reply to this: 7823
Author: Zach 
Type: Update 
Category: PSL 
Subject: PMC calibration for MC_F calibration 

In order to have less unknown, you can calibrate the PMC PZT separately. Lock the PMC and take a transfer function from either the NPRO PZT input or the FSS AOM VCO input to the PMC control signal. The VCO is better, since the calibration should be much better known, but I am not sure what the current setup of the 40m PSL is, so I don't know if the FSS is normally locked.

Since you know the NPRO PZT or VCO actuation coefficients, you can assume the PMC loop (where the OL gain is high enough) is correcting for the frequency fluctuations. So, simply multiply the known coefficient by the transfer function to get the PMC PZT gain.

Then, you can re-do your PMC PZT sweep measurement and be confident of the calibration. The FSR must be right, so you can get the finesse with confidence.

Quote:

Hmm... Does anyone find falses in my measurement?
If not, the finesse can be 4 times smaller than the value which was 5 years ago?

 

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