Interferometer Control in a Laser Interferometer Gravitational Observatory

Martin Regehr, Physics, Caltech

The operation of a planned Laser Interferometer Gravitational Observatory (LIGO) and the need for a control system for it are explained. Procedures used to analyze and model the plant (the laser interferometer) are presented. The plant is ill-conditioned. Sources of disturbance and the degree to which they must be suppressed are identified, and bandwidth-limiting plant uncertainties are described. Loop gain requirements are discussed for the control of a 2x2 subsystem of the plant with two SISO controllers.