Image Processing Reference
In-Depth Information
Image-Stabilization Systems Simplified
Figure 5.7 A representative transfer function for the tilt mirror showing resonance
points in (a) amplitude and (b) phase space.
changes by 180 deg. As a result, when operating at resonance, the system is com-
pletely unstable. This is the fundamental limitation on the bandwidth of the tilt mir-
ror, and thus the image-stabilization system. If the system is pushed to operate at
higher speeds, it will become unstable and it will be impossible to control the posi-
tion of the light. Higher bandwidths can be achieved with this mirror system,
provided that speaker performance is compensated.
5.4.4 Control system
Image stabilization is provided by taking the signals from the PSD and converting
them into corrections that can be applied to the tilt compensator. The control sys-
tem accomplishes this. Many types of controllers are available for this task, but un-
der many situations the simplest and least expensive is built around a standard com-
puter. The computer provides the rules for adjusting the mirror position based on
the spot position on the optical sensor. The signals must still be processed and
brought into the computer.
The signal interfaces, though not part of the actual control system, bring signals
from the optical sensor into the computer and sends the driving signals out to the tilt
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