FSM-300 or FSM-320 Fast Steering Mirror & FSM-CD300B ...

System Components 35
Logic Unit keeps the FSM’s on Internal Control and flags an error to the
operator.
The external feedback signals should be scaled so that ±10V yields ±26 mrad
of mechanical rotation. Care needs to be taken to align the external sensors so
that X and Y rotation axes of the FSM correspond to the correct X and Y
outputs of the quad / lateral effect cell amplifier.
Reference position voltages can be applied to the Command Inputs so that if
the INT/EXT selector switch voltage input returns to Internal Control mode,
the FSM will move to a defined position. Otherwise the mirror will return to
the powered-on null position.
Figure 19: FSM configured with external feedback sensor for laser beam stabilization.
6.7 Open Loop Control Mode
The Model FSM-CD300B controller/driver can be used in Open Loop mode,
which does not make use of External or Internal feedback signals. The Open
Loop mode is selected by applying a high TTL-level signal X_OL_SW
selector switch for X (Pin 9) and/or Y_OL_SW selector switch for Y (Pin
10). The Open Loop command signals are applied to the X_OL_CMD input
for X (Pin 22) and/or Y_OL_CMD input for Y (Pin 24). These input are
single-ended. Ground pins are adjacent on Pins 23 and 25.