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HA0373T Rev Ck May 2017
Chapter 5
Using the GUI Displays
The small left hand display shows the detector XDiff, YDiff and Sum signal values in
Volts. Also shown are the XOut and YOutvalues, which are applicable in ‘closed loop
mode only. These values show the low voltage position demand signals applied to the
piezos in order to keep the beam central in the detector.
The main, right hand display shows either a representation of the XDIFF and YDIFF
values or the XOut and YOut position demand signals applied to the piezos,
depending on the XY Display Mode selected. The display also shows a bar graph,
which represents the Sum value from the detector.
Viewed together, these displays are useful in deciding when to center the piezo
actuators and make manual adjustments to the turning mirror actuators.
For example, consider the situation shown below, when the unit is in open loop mode
and the display shows the beam in the upper right hand quadrant of the detector
array. Let’s also assume that the output to the piezo drivers is around 1V as indicated
by the X Out and Y Out values. This means that the actual piezo drive voltages for a
75V piezo will be about 7.5V (15V for a 150V piezo
Fig. 5.9 Displays Showing Values Near Travel Limit
