Multi-rate control of high-order adaptive optics systems

Next generation adaptive-optics systems (AO) have unprecedented complexity. The proposed number of degrees-of-freedom has considerably increased, putting the focus on the real-time processing capabilities. Second generation instrumentation for the Very-Large Telescope (VLT) is one such case. We present a method capable of lowering the average computational effort (i.e. lowering the average equivalent frame-rate) and deliver the same performance figures. It consists of applying a distributed set of frame rates to outperform the conventional vector-matrix multiplies (VMM) used for modal reconstruction and control in AO systems when Zernike polynomials or Karhunen-Loeve modes are used as basis. We analyse the low and high-noise regimes for which we outline the theoretical key points and present both semi-analytical and Monte-Carlo simulation results having as baseline a Planet-Finder-like (PF) system.