Strategies for the deconvolution of hypertelescope images

The authors present the simulation of hypertelescope images for an array of cophased densified apertures. They distinguish between two types of aperture densification, one called FAD corresponding to Labeyrie's original technique, and the other FSD corresponding to a densification factor twice as low. Images are compared to the Fizeau mode. A single image of the observed object is obtained in the hypertelescope modes, while in the Fizeau mode the response produces an ensemble of replicas of the object. Simulations are performed for noiseless images and in a photodetection regime. Assuming first that the point spread function (PSF) does not change much over the object extent, they use two classical techniques to deconvolve the images, namely the Richardson-Lucy and image space reconstruction algorithms. Both algorithms fail to achieve satisfying results. They interpret this as meaning that it is inappropriate to deconvolve a relation that is not a convolution, even if the variation in the PSF is very small across the object extent.