Beam Stabilization
A rather simple example is the stabilization of the position and direction of laser beam between modules in a large free space optical communication system. Fourier optics is used to control both direction and position. The actual beam is measured by photo diodes. This signal is fed into some Analog-to-digital converters and a microcontroller runs a PID controller algorithm. The controller drives some digital-to-analog converters which drive stepper motors attached to mirror mounts.
If the beam is to be centered onto 4-quadrant diodes, no Analog-to-digital converter is needed. Operational amplifiers are sufficient.
Read more about this topic: Adaptive Optics
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