Stellar scintillations as a remote atmospheric wave-front sensor.

Stellar scintillations are considered noise in adaptive-optics sensors and are measured for calibration purposes only. We propose to use scintillations to provide direct instantaneous information about the structure of the atmosphere. As a result it will be possible to increase the field of view provided by adaptive optics. The scintillation pattern is created when stellar light is diffracted by high-altitude turbulence. Alternatively, this pattern can be viewed as a Laplacian of this turbulence and can thus be inverted to estimate it. The measurement is limited by the intensity and the angular size of the reference star, by the height distribution of the atmospheric turbulence, and by the detector resolution and spectral response.