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HA0303T Rev A Feb 2014
Chapter 4
4.4
Operating Modes
The MODE button on the top panel, is used to toggle between Monitor, Open Loop
and Closed Loop modes.
When operating in 'Monitor' mode (top panel OPEN and CLOSED LOOP LEDs not
lit), the X axis (XDIFF) and Y axis (YDIFF) difference signals from the detector, are
fed through to the rear panel SMA connectors for use in a monitoring application - see
Fig. 4.6.
Fig. 4.6 MONITOR Mode Schematic Diagram
When in ‘Open Loop’ mode, the signals on the rear panel LV OUT/XDIFF and
LV OUT/YDIFF connectors now represent the XOut and YOut position demand
signals, used to position the beam steering element. These signals are either fixed
at zero (0V), or held at the last Closed Loop value (depending on the ‘
Position
Demands In Open Loop Mode
’ parameter in the Settings panel - see Section 6.2.) -
see Fig. 4.7 This is useful when the system is being adjusted manually, to position
the light beam within the detector array.
PDQ80A
Quad Detector
A/D
A/D
A/D
DSP
XDIFF
YDIFF
SUM
USB
LV OUT XDIFF
LV OUT YDIFF
SUM
MONITOR MODE: The XDIFF, YDIFF and SUM signals are routed to the
corresponding SMA connectors.
The DSP
monitors
the position of the light beam and measures the XDIFF,
YDIFF and SUM signals.
