Efficient phase estimation for large-field-of-view adaptive optics

We propose a maximum a posteriori-based estimation of the turbulent phase i n a large field of view (FOV) to overcome the anisoplanatism limitation in adaptive optics. We show that, whatever the true atmospheric profile, a sma ll number of equivalent layers (two or three) is required for accurate rest oration of the phase in the whole FOV. The implications for multiconjugate adaptive optics are discussed in terms of the number and conjugated heights of the deformable mirrors. The number of guide stars required for wave-fro nt measurements in the field is also discussed: three (or even two) guide s tars are sufficient to produce good performance. (C) 1999 Optical Society o f America.