Direct imaging with highly diluted apertures. II. Properties of the point spread function of a hypertelescope

TL;DR

This paper investigates the properties of point spread functions in hypertelescopes, highlighting how array configuration affects image resolution, halo level, and field of view, with implications for future large-scale optical interferometers.

Contribution

It provides a detailed analysis of how array configuration impacts image quality and field of view in hypertelescope imaging, using numerical simulations to guide optimal design choices.

Findings

Regular array patterns optimize image quality but reduce field of view.

Non-redundant arrays are less sensitive to space aliasing effects.

Array configuration involves a trade-off between resolution, halo level, and field of view.

Abstract

In the future, optical stellar interferometers will provide true images thanks to larger number of telescopes and to advanced cophasing subsystems. These conditions are required to have sufficient resolution elements (resel) in the image and to provide direct images in the hypertelescope mode. It has already been shown that hypertelescopes provide snapshot images with a significant gain in sensitivity without inducing any loss of the useful field of view for direct imaging applications. This paper aims at studying the properties of the point spread functions of future large arrays using the hypertelescope mode. Numerical simulations have been performed and criteria have been defined to study the image properties. It is shown that the choice of the configuration of the array is a trade-off between the resolution, the halo level and the field of view. A regular pattern of the array of telescopes optimizes the image quality (low halo level and maximum encircled energy in the central peak), but decreases the useful field of view. Moreover, a non-redundant array is less sensitive to the space aliasing effect than a redundant array.