RECOVERY OF PLANETARY IMAGES BY SPECKLE IMAGING

Limits to the recovery of planetary images by speckle imaging were investigated by means of a numerical simulation of the image-forming process. Laboratory measurements established that the numerical model correctly represented the process. With this numerical model we studied the observing conditions required to obtain useful planetary data for Neptune and Io, and we learned which factors are important for the successful recovery of images. We also showed that our methods of amplitude and phase recovery do not contribute to image degradation, which is essentially caused by photon noise alone. From this conclusion we were led to two simple models of speckle imaging that involve neither details of the recovery procedure nor of the atmospheric behavior (except for the size of the seeing disk). Both models are governed by a dimensionless ratio that involves all parameters relevant to the process of image restoration. The models can be used by any observer, and they have been used by us to predict the performance of speckle imaging for T-tauri stars and for a Mars cloud study.