  The Adaptive Optics Lucky Imager (AOLI) is a new instrument under development
to demonstrate near diffraction limited imaging in the visible on large
ground-based telescopes. We present the adaptive optics system being designed
for the instrument comprising a large stroke deformable mirror, fixed component
non-linear curvature wavefront sensor and photon-counting EMCCD detectors. We
describe the optical design of the wavefront sensor where two photoncounting
CCDs provide a total of four reference images. Simulations of the optical
characteristics of the system are discussed, with their relevance to low and
high order AO systems. The development and optimisation of high-speed wavefront
reconstruction algorithms are presented. Finally we discuss the results of
simulations to demonstrate the sensitivity of the system.
