Modal Fourier wavefront reconstruction using graphics processing units

Large degree-of-freedom, real-time adaptive optics control requires reconstruction algorithms that are computationally efficient and readily parallelized for hardware implementation. Poyneer [J. Opt. Soc. Am. A , 2100-2111 (2002)] have shown that the wavefront reconstruction with the use of the fast Fourier transform (FFT) and spatial filtering is computationally tractable and sufficiently accurate for its use in large Shack-Hartmann-based adaptive optics systems (up to 10,000 actuators). We show here that by the use of graphical processing units (GPUs), a specialized hardware capable of performing FFTs on big sequences almost 5 times faster than a high-end CPU, a problem of up to 50,000 actuators can already be done within a 6-ms limit. We give the method to adapt the FFT in an efficient way for the underlying architecture of GPUs.