arXiv subjects

Matteo Taccola

Publications and source records attributed to Matteo Taccola.

4 recordsLinked to original sources

arXiv2026

First high-contrast results on THD2 testbed after infrastructure upgrade

We present the first scientific results delivered by the upgraded THD2 high-contrast imaging testbed. We report two advances enabled by its improved stability and broadband performance. First, for the Roman Space Telescope, we demonstrate that Gaussian-shaped diversity probes outperform the baseline sinc probes by reducing non-linearities, supporting higher probe amplitudes, and improving electric field estimation efficiency. These results have led to their prioritization as an enhanced early observation for Roman. Second, within ESA's SUPPPPRESS project, we test new polarization-independent Vector Vortex Coronagraphs and design them to high-contrast performance approaching 1e-10 over a 20% bandwidth. We assess their behavior in narrow- and broadband light with active focal-plane wavefront control. Together, these results show how THD2 strengthens Europe's capability in high-contrast imaging, providing a unique platform reaching contrasts of 1e-8 to 1e-9 for developing next-generation coronagraphic technologies.

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arXiv2026

SUPPPPRESS: Prototyping and testing liquid-crystal vector vortex coronagraphs with reduced polarization leakage

The vortex coronagraph is one of the most promising candidates for the Habitable Worlds Observatory (HWO) due to its excellent theoretical performance for an off-axis telescope. A practical realization can be achieved using liquid-crystal polymers to form a vector vortex coronagraph (VVC). Reaching the $10^{-10}$ contrast required for Earth-like planet detection is, however, limited by polarization leakage caused by wavelength-dependent deviations from half-wave retardance. This effect can be mitigated using multi-layer twisted retarders to minimize leakage, and by combining the VVC with multiple polarization gratings (mgVVC) to diffract the polarization leakage out of the science path. We present recent progress within the ESA-funded SUPPPPRESS project, which aims to advance the manufacturing, assembly, and testing of high-performance VVCs. Central singularities of 2 and 6 $\mu$m have been achieved for charge 2 and charge 6 VVCs, respectively, with patterning accuracies better than 1 degree root-mean-square error. Fabrication procedures have been developed to produce individual components with a polarization leakage of $3\times10^{-4}$ over a 10% bandwidth and $8\times10^{-4}$ over a 20% bandwidth. We also report on the development of assembly and alignment procedures for mgVVCs and their metrology. Furthermore, we present initial high-contrast tests at the THD2 bench for both regular VVCs and a double-grating VVC. The double-grating VVC reaches an average contrast between 3 and 10 $\lambda$/D of $2 \times 10^{-8}$ over a small bandwidth and $6\times 10^{-8}$ over a 10% bandwidth. Finally, we report on successful space-environment tests of the assembled liquid-crystal masks.

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arXiv2024

Prototyping liquid-crystal coronagraphs for exo-Earth imaging

This paper presents initial results from the ESA-funded ``SUPPPPRESS'' project, which aims to develop high-performance liquid-crystal coronagraphs for direct imaging of Earth-like exoplanets in reflected light. The project focuses on addressing the significant challenge of polarization leakage in vector vortex coronagraphs (VVCs). We utilize newly manufactured multi-grating, liquid-crystal VVCs, consisting of a two- or three-element stack of vortex and grating patterns, to reduce this leakage to the $10^{-10}$ contrast level. We detail the experimental setups, including calibration techniques with polarization microscopes and Mueller matrix ellipsometers to enhance the direct-write accuracy of the liquid-crystal patterns. The performance testing of these coronagraph masks will be conducted on the THD2 high-contrast imaging testbed in Paris.

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arXiv2020

UV astronomy with small satellites

Small satellite platforms with high performance avionics are becoming more affordable. So far, with a few exceptions, small satellites have been mainly dedicated to earth observation. However, astronomy is a fascinating field with a history of large missions and a future of promising large mission candidates. This prompts many questions; can the recent affordability of small satellites change the landscape of space astronomy? What are the potential applications and scientific topics of interest, where small satellites could be instrumental for astronomy? What are the requirements and objectives that need to be fulfilled to successfully address the astronomical investigations of interest? Which kind of instrumentation suits the small platforms and the scientific use cases best? This paper discusses possible scientific use cases that can be achievable with a relatively small telescope aperture of 36 cm, as an example. The result of this survey points to a specific niche market -astronomy observation in the UV spectral range. UV astronomy is a research field which has had valuable scientific impact. It is, however, not the focus of many current or past astronomical investigations. UV astronomy measurements cannot be made from earth, due to atmospheric absorption in this spectral range. The research field is currently sparsely addressed but of scientific interest for a large community. Small satellites offer the opportunity to provide more means of research for UV astronomy. Therefore, this paper also presents an instrument design with a modest telescope aperture, a spectrometer and a detector that is suitable for observations in the UV. The observatory design can be accommodated on small platforms for the selected scientific use cases. It fulfills the scientific objectives and requirements of those use cases.

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