ANALYSIS OF MULTICONJUGATE ADAPTIVE OPTICS

We investigate a method for widening the compensated field of view of an adaptive-optical telescope with multiple deformable mirrors and an array of artificial guide stars. An ensemble of wave-front sensor measurements, made with the individual guide stars in the array, is used to estimate the contribution of a region of the atmosphere to the cumulative phase distortion. Our analysis includes the effects of measurement noise, wave-front-sensor sampling, and reconstruction of the wave front from slope measurements. We performed numerical computations for an atmosphere consisting of two turbulent layers: one at 1% of the guide-star altitude with 90% of the total turbulence strength and one at 10% of the guide-star altitude with the remaining 10% of the total turbulence strength. If we assume that r(0) = 0.15 m and that a photon-limited wave-front sensor detecting 50 photons/r(0)-sized subaperture is used, the results indicate that a 0.9-m-square telescope with a diagonal field of view of similar to 92 mu rad approximate to 19 arcsec can use two deformable mirrors, four laser guide stars, and a natural tilt reference star to achieve an rms residual phase error that is <lambda/7 over its entire field of view.