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Entry  Mon Mar 27 20:41:21 2017, rana, gautam, Update, PSL, PMC DAQ assay for feed-forward integration TEK00000.PNG20170327_194931.jpg20170327_204554.jpg
    Reply  Wed Mar 29 11:41:19 2017, gautam, Update, PSL, PMC DAQ assay for feed-forward integration C1ALS_PSLnamespace.pngPMCcheckout.pdfD980352-A-40m_151119.pdf
       Reply  Thu Mar 30 00:16:09 2017, gautam, Update, PSL, PSL NPRO PZT calibration 
          Reply  Mon Apr 3 17:25:13 2017, gautam, Update, PSL, PSL NPRO PZT calibration PDHerr.pdfNPROcalib.pdf
             Reply  Tue Apr 4 17:27:58 2017, rana, Update, PSL, PSL NPRO PZT calibration 
       Reply  Thu Mar 30 18:11:01 2017, rana, Update, PSL, PMC DAQ assay for feed-forward integration 
          Reply  Mon Apr 3 23:07:09 2017, gautam, Update, PSL, PMC DAQ assay for feed-forward integration 
             Reply  Tue Apr 11 00:38:37 2017, gautam, Update, PSL, PMC demod moved off servo board PMC_Ctrl_spec.pdf
                Reply  Wed Apr 12 00:36:53 2017, gautam, Update, PSL, PMC demod moved off servo board PMC_digitalSpec.pdfPMC_DAQ_spectra.pdf
                   Reply  Tue Apr 18 01:01:03 2017, gautam, Update, PSL, PMC OLTF measured, DAQ channels calibrated PMCspectra_calibrated.pdfPMC_MEDMs.png
                      Reply  Tue Apr 18 16:10:00 2017, gautam, Update, PSL, PMC OLTF measured, DAQ channels calibrated PMC_OLTF_170418.pdf
                         Reply  Tue Apr 18 23:37:15 2017, rana, Update, PSL, PMC OLTF measured, DAQ channels calibrated 
                         Reply  Wed Apr 19 15:13:30 2017, gautam, Update, PSL, PMC/MCL multicoherence PMC_MCL_multicoherence.pdf
Message ID: 12925     Entry time: Mon Apr 3 17:25:13 2017     In reply to: 12918     Reply to this: 12928
Author: gautam 
Type: Update 
Category: PSL 
Subject: PSL NPRO PZT calibration 

Summary:

By sweeping the laser frequency and looking at the PMC PDH error signal, I have determined the 2W Mephisto Innolight PZT actuator gain to be 1.47 +/- 0.04 MHz/V

Method:

  1. Re-aligned the input beam into the PMC to maximize transmission level on the oscilloscope on the PSL table to 0.73V.
  2. Disabled control signal from IMC servo to PSL. 
  3. Unlocked the PMC and disabled the loop by selecting "BLANK" on the PMC MEDM screen.
  4. Connected a 0.381 Hz 5Vpp triangular wave with SR function generator to the "SUM" input of the Fast I/F box just before the PSL PZT input. These params were chosen considering the Pomona box just before the NPRO has a corner at 2.9Hz, and also to sweep the voltage to the NPRO PZT over the full 150V permitted by the Thorlabs HV amplifier unit. Monitored the voltage to the Thorlabs HV amp from the "AFTER SUM" monitor point on the same box. Monitored the PMC PDH error signal using the single-pin LEMO monitor point on the PMC servo board (call this Vmon). Both of these signals were monitored using a Tektronix digital O'scope.
  5. Downloaded the data using ethernet.
  6. Fit a line to the voltage applied to the NPRO PZT - I assumed the actual voltage being applied to the PZT is 15*Vmon, the pre-factor being what the Thorlabs HV amplifier outputs. The zero crossings of the sideband resonances in the PDH error signal are separated by 2*fmod (separated by fmod from the carrier resonance, fmod = 35.5MHz assumed). With this information, the x-axis of the sweeps can be converted to Hz, from which we get the PZT actuator gain in MHz/V. 

An example of the data used to calculate the actuator gain (left), and the spread of the calculated actuator gain (right - error bars calculated assuming 5e-4 s uncertainty in the sideband zero-crossing interval, and using the error in the slope of the linear fit to the sweep voltage):

This will now allow calibration of the PMC DAQ channels into Hz.

GV 4 April - The y-axis of the lower plot in Attachment #1 has mis-labelled units. It should be [V], not [MHz/V].

Attachment 1: PDHerr.pdf  114 kB  | Hide | Hide all
PDHerr.pdf
Attachment 2: NPROcalib.pdf  16 kB  | Hide | Hide all
NPROcalib.pdf
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