Image reconstruction for kernel phase interferometry with SCExAO/CHARIS using gradient descent

Alexander Chaushev; Stephanie Sallum

doi:10.1117/12.2677213

5 October 2023 Image reconstruction for kernel phase interferometry with SCExAO/CHARIS using gradient descent

Proceedings Volume 12680, Techniques and Instrumentation for Detection of Exoplanets XI; 126800O (2023) https://doi.org/10.1117/12.2677213
Event: SPIE Optical Engineering + Applications, 2023, San Diego, California, United States

Abstract

Kernel Phase Interferometry (KPI) is a data processing technique which enhances the angular resolution achievable by a conventional telescope in space or behind a powerful adaptive optics system. KPI is increasingly being applied to observations of young stars, which often host circumstellar disks with complex structure. Since such observations rely on fitting to an interferometric observable (the kernel phase), developing a flexible modelling approach in the form of an image reconstruction code would be greatly beneficial for recovering complex asymmetries. Here we present a proof-of-concept for such an image reconstructor that makes use of automatic differentiation to compute a gradient and Stochastic Gradient Descent (SGD) to find the best fitting image. Using simulated signals, we show that this approach works well for the case of a point-like companion but requires further development to robustly recover extended emission from a disk. This may be made possible by adding one of the many commonly applied regularizers for long-baseline or aperture masking image reconstruction and implementing a more sophisticated variant of gradient descent. Nevertheless, this simple combination of automatic differentiation and SGD shows promise for being a powerful addition to the KPI toolbox.

Conference Presentation

(2023) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Alexander Chaushev and Stephanie Sallum "Image reconstruction for kernel phase interferometry with SCExAO/CHARIS using gradient descent", Proc. SPIE 12680, Techniques and Instrumentation for Detection of Exoplanets XI, 126800O (5 October 2023); https://doi.org/10.1117/12.2677213

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