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Message ID: 7323     Entry time: Thu Aug 30 20:31:35 2012
Author: Jenne 
Type: Update 
Category: IOO 
Subject: PZT1 and PZT2 set to center of their ranges 

[Koji, Jenne]

Jamie and Koji pointed out that we need to be doing the in-vac alignment with the PZTs at the center of their ranges.  Also, we confirmed that they were set to "closed loop off", so the strain gauges were not supplying any feedback.

PZT1 was set to 0 for both pitch and yaw, since it has a very limited range of motion right now, so 0 is close enough.

For PZT2, Koji and I moved the slider in pitch and yaw, and watched the LCD output monitor on the PZT driver at the bottom of 1Y3.  We saw the value on the LCD change between slider values +4 to -6 for PZT2 yaw, so it is set to -1 as the center.  We saw the value on the LCD change between slider values -4 to +5 for PZT2 pitch, so it is set to +0.5 as the center.   Beyond these slider values (the sliders all go -10 to +10), the LCD value didn't change, either at 0, or at the maximum. 

Since PZT1 doesn't really move, this shouldn't affect any of the alignment work that Suresh and I did last night, although we should quickly confirm tomorrow. On the agenda for tomorrow is adjusting PZT2 such that we hit the center of PR2 (and hopefully that will also put us through the center of the PRM target, if the alignment was done well enough last time), so it's okay that we have only now set it to the center of its range.

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