A Large Dynamic Range Digital Controller for use with CO₂ Pumped Fir Lasers

CO₂ pumped FIR (Far Infrared) lasers have a number of valuable uses in the diagnostics arena of fusion research. To maintain lasing, the tuning of the two lasers must be tightly coupled. This coupling presents interesting control problems. A number of analog approaches have been employed to implement tightly coupled tuning control. Such implementations, however, suffer from a lack of flexibility. A new digital controller has been developed that greatly increases the range of control strategies that may be implemented. Of further interest is the controller's capability to provide 96dB of dynamic range when driving −200V piezoelectric transducers. This paper will discuss the algorithms and hardware used in this controller. Lessons learned from the development effort will presented.