title: Hierarchical wave-front sensing.
abstract: We present a new wave-front sensing technique for adaptive optics based on use of several wave-front sensors dedicated to the sensing of a different range of spatial frequencies. We call it a hierarchical wave-front sensor. We present the concept of a hierarchical wave-front sensor and apply it to the Shack-Hartmann sensor. We show the gain that is expected with two Shack-Hartmann sensors. We obtain a gain that increases with the size of the largest sensor, and we detail the application of hierarchical wave-front sensing to extreme adaptive optics and extremely large telescopes.
authors.affiliation: Osservatorio Astrofisico di Arcetri, Largo E. Fermi, Firenze 55125, Italy. leroux@arcetri.astro.it
authors.forename: Brice
authors.initials: B
authors.lastname: Le Roux
authors.forename: Julien
authors.initials: J
authors.lastname: Coyne
authors.forename: Roberto
authors.initials: R
authors.lastname: Ragazzoni