Novel closed-loop sparse iterative control algorithms have recently
been introduced for single-conjugate and multi-conjugate adaptive optics
(MCAO) systems. We present a scalable conjugate gradient (CG) based
control algorithm using (i) a layer-oriented sparse low-pass filtering
iteration to disentangle the atmospheric layers and estimate the residual
error signal at all layers, and (ii) a temporal filtering step to control
a cascaded system of several high-order wavefront correctors conjugated to
different altitudes.