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HA0373T Rev Ck May 2017
Chapter 4
4.6.6
Using the Target Display
The ‘target’ display shows the horizontal and vertical position of the laser beam within
the detector sensor array. When used in conjunction with the display on the piezo
cubes, it can also be used to show when the piezo actuators are near the ends of their
travel and need re-centering. This will require manual adjustments to the turning
mirror actuators.
For example, consider the situation shown below, when the unit is in open loop mode
and the spot is in the upper right side of the display. This indicates that the laser beam
is in the upper right hand quadrant of the detector array. Let’s also assume that the
piezo drivers controlling the piezo mirror show around 10V.
Fig. 4.11 TARGET and VOLTS Displays Showing Values Near Travel Limit
When the unit is switched to closed loop mode, the spot moves towards the center of
the display, as the piezo units drive the piezo mirror to reposition the laser beam.
Fig. 4.12 Repositioning the Laser Beam
But the piezo units now show 0V which means that the piezos are at the limit of their
travel and cannot drive the pi ezo mirror further. The piezo actuators must be
recentered (i.e. OUTPUT pot adjusted for 37.5V display), and the position error taken
up by manual adjustment.
Piezo Controller
MENU
Piezo Controller
MENU
V o l t a g e : 1 0 . 0 V
7 5 V N V
V o l t a g e : 1 0 . 0 V
7 5 V N V
Position Aligner
MENU
X + 8 . 6 9 1 + 0 . 0 0 0
Y + 8 . 0 6 5 + 0 . 0 0 0
Piezo Controller
MENU
Piezo Controller
MENU
V o l t a g e : 0 . 0 V
7 5 V N V
V o l t a g e : 0 . 0 V
7 5 V N V
Position Aligner
MENU
X + 4 . 7 9 1 + 0 . 0 0 0
Y + 4 . 1 3 4 + 0 . 0 0 0
