Results from simulations

Previous theoretical studies have indicated that the timescales and isoplanatic angles relevant to speckle imaging may be larger than those for non-conjugate adaptive optics at many astronomical observatories. Numerical simulations presented here were broadly consistent with these predictions.

High Strehl ratio images would be expected from the Lucky Exposures technique even if there are aberrations in the telescope mirror, as the method will tend to select exposures at times when the atmosphere is counter-acting the mirror aberrations. Structure on the mirror surfaces which is on very different scales to the dominant atmospheric perturbations is much less likely to be corrected in this way.

Sinc-resampling of the short exposures can significantly improve the estimation of the Strehl ratio and position of the brightest speckle. In low signal-to-noise data, Fourier filtering can be used to improve the performance of the exposure selection and re-centring, and reduce the noise in the final reconstructed image.