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Entry  Thu Jul 12 21:16:25 2018, aaron, Update, OMC, Checking OMC Electronics 
    Reply  Sat Jul 14 16:04:34 2018, aaron, Update, OMC, Checking OMC Electronics Screenshot_2018-07-14_17.53.40.pngScreenshot_2018-07-14_17.57.17.png
       Reply  Sat Jul 21 01:14:02 2018, gautam, Update, OMC, PZT Jena driver board check 
Message ID: 14095     Entry time: Sat Jul 21 01:14:02 2018     In reply to: 14072
Author: gautam 
Type: Update 
Category: OMC 
Subject: PZT Jena driver board check 

[Aaron, gautam]

We did a quick check of this board today. Main takeaways:

  • There are two voltages (HV pos and HV neg) that are output from this unit.
  • Presumably, these goto different piezoelectric elements, referenced to ground. Are there any spec sheets for these describing the geometry/threshold voltages?
  • The outputs are:
    • \mathrm{HV_{+}} = 10(V_{\mathrm{DAC}}+V_{\mathrm{offset}}), \mathrm{HV_{-}} = 10(-V_{\mathrm{DAC}}+V_{\mathrm{offset}})
    • So with V_{\mathrm{offset}} = 7.5 \mathrm{V}, we expect to be able to use +/- 7.5 V of DAC range.
  • The trim pot had to be adjusted to realize V_{\mathrm{offset}} = 7.5 \mathrm{V}​.
  • I assume 150V is some kind of damage threshold of the PZT, so there is no benefit to using 10V offset voltage (as this would result in 200 V at full range DAC voltages).

With the correct V_{\mathrm{offset}} = 7.5 \mathrm{V}, we expect 0V from the DAC to result in 0 actuation on the mirror, assuming that an equal 75V goes to 2 PZTs mounted diametrically opposite on the optic. Hopefully, this means we have sufficient range to scan the input pointing into the OMC and get some sort of signal in the REFL signal (while length PZT is being scanned) which indicates a resonance. 

We plan to carve out some IFO time for this work next week.

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