L’Ottica Adattiva in Astronomia in Italia

L’Ottica Adattiva in Astronomia in Italia

Roberto Piazzesi, INAF-Osservatorio Astronomico di Roma

SHARK-VIS final integration report

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.1

The SHARK-VIS high-contrast visible imager has completed its laboratory integration phase and is ready for installation at LBT. After completion of the PAE (Preliminary Acceptance in Europe), SHARK-VIS will perform a run as visiting instrument at the AEOS telescope in Hawai’i to test performance, speed up commissioning, and verify reduction pipelines before moving to LBT. We present here results of the performance tests on the ADONI testbench and a timeline for the near future.

Essna Ghose, INAF-Osservatorio Astrofisico di Arcetri

Current status of SOUL at the Large Binocular Telescope

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.2

SOUL project is the upgrade of the 4 SCAO systems at the Large Binocular Telescope with the goal of pushing the current guide star limits to about 2 magnitudes fainter – thanks to the Electron Multiplied CCD detectors. Here, we will report about the project status: both systems installed on the SX eye of LBT are now operational, while the commissioning of the DX ones is scheduled for the upcoming months. Further, we will mention some of the new technicalities introduced in order to improve both system performances and robustness. Finally, we will highlight some of the astronomical observations performed so far with SOUL, together with an eye on data reduction challenges.

Enrico Pinna, INAF-Osservatorio Astrofisico di Arcetri

MAVIS Adaptive Optics Module status

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.3

MAVIS is the next imager and spectrograph for the VLT, fed by a common MCAO system, that will provide a 30” FoV in the visible. The AO Module scheme includes means to sense 8 LGSs and 3 NGSs at the same time and drive more than 5000 actuators, divided into 3 DMs (including UT4 DSM). The system also includes some auxiliary loops, to push the stability of the main AO loop and the overall performance. Here we present the Preliminary Design of the AOM, its main calibration strategy and the main results of the performance and stability analyses

Cedric Antoine Adrien Gabriel Plantet, INAF-Osservatorio Astrofisico di Arcetri

Fine phasing of the Giant Magellan Telescope in closed loop

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.4

The Giant Magellan Telescope Organization (GMTO) and the Adaptive Optics (AO) team of Arcetri have been collaborating in the last decade to design the Natural guide star Wavefront Sensor (NGWS) for the Natural Guide Star AO mode of the GMT. The GMT’s primary and deformable secondary mirror are each composed of 7 segments, and a critical task of the NGWS will be to keep these 7 segments in phase in addition to the classical AO correction. The baseline defined several years ago has two pyramid wavefront sensors working in the visible. The first one is used to close the AO loop (main channel), but it is not sensitive to differential pistons that are multiples of its central wavelength (lambda1), leading to segment ejections. The second pyramid, sensing at a slightly higher wavelength, is then used as a slow “truth sensor” (2nd channel) to derive the sign of a segment ejection and correct it by steps of lambda1. However, the robustness of this solution with respect to noise and turbulence conditions is not satisfying.
We are now in a prototyping phase, for which the first step is to improve the baseline or find an alternative design for the 2nd channel in order to gain robustness. We present this study, based on three potential sensing solutions: the pyramid, the Zernike phase contrast and focal-plane sensing with LIFT. We also report on a few lessons learned on differential piston sensing that might be of interest for systems facing issues with the so-called island effect and/or low-wind effect.

Simone Antoniucci and Manuele Ettore Gangi, INAF-Osservatorio Astronomico di Roma

Science with ELVIS, the IFS upgrade of SHARK-VIS

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.5

ELVIS (Exoplanets at LBT with a Visible IFS for Shark-vis) is the integral field spectrograph upgrade that will be installed on SHARK-VIS. In this talk we will present some of the exciting new scientific aspects that ELVIS will allow us to investigate. We will focus in particular on the analysis of very young planets in formation within the disk of their parental star, which represent the key science project for SHARK-VIS. With a goal spectral resolution around R=15000, ELVIS will be able to resolve for the first time the profile of the Hα line emitted by accreting giant planets, which will provide crucial information to constrain planetary accretion and formation models. We will show simulations of ELVIS observations for a number of accreting planets with different parameters, which will highlight the capabilities of the instrument and its potential breakthrough scientific contribution.

Paolo Saracco, INAF-Osservatorio Astronomico di Brera

SHARP a near-IR suite for ELT

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.6

It is the joining of the largest aperture with the Adaptive Optics (AO) systems that will allow ELT to provide unparalleled data, sharper and deeper than JWST. Therefore, the spectrograph foreseen at the 2nd port of MAORY@ELT will be the most powerful and coveted instrument in the JWST era, the one able to see what the others cannot. SHARP is a concept study for a near-IR (0.95-2.5 mu) spectrograph conceived for the 2nd port of MAORY@ELT. SHARP is composed of a Multi-Object Spectrograph (MOS) and a multi Integral Field Unit (mIFU). The wavelength range extending up to ~2.5 mu and the AO-assisted observing mode, will complement MOSAIC and ANDES, both limited to 1.8 mu and not supported by AO systems, allowing us to study the physics of the formation and the evolution of galaxies and the very distant Universe at unprecedented details. In this talk I will present the scientific motivations behind SHARP, the main requirements, the current team, the status and the issues of the study. The aim is to stimulate interest among the technological community to find support and help to carry on the pre-phase A study of SHARP.

Ivan Di Antonio, INAF-Osservatorio Astronomico d’Abruzzo

A Calibration Unit for MAORY: current status & future challenges

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.7

The Calibration Unit (CU) is a subsystem of MAORY (Multi-conjugate adaptive Optics Relay for ELT Observations) that, providing suitable light sources, will enable MAORY to run calibration templates as well as verification and test procedures, in standalone mode, drastically reducing the amount of required night-time for such operations. The CU will be also used to ease the alignment of MAORY and to test and verify its performances (during the AIV phase). The requirements and constraints imposed at system and subsystem level have made the design challenging and have necessitated an in-depth study of every aspect of the design already in its preliminary phase.
The current status of the design is shown and the main analyses carried out to assess the performances and to validate the preliminary design are presented.

Marco Riva, INAF-Osservatorio Astronomico di Brera

Optomechanical Design

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.8

Alessio Turchi, INAF-Osservatorio Astrofisico di Arcetri

PSF forecast – A preliminary feasibility study

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.9

In recent years Manua Kea, LBT, and now also ESO, have been implementing an atmospheric turbulence forecast scheme. With advance knowledge of turbulence conditions becoming more and more available, and the availability of highly specialized simulation software such as PASSATA or the more recent TIPTOP, it has become conceivable to think about predicting the PSF figures of merit (namely SR and FWHM) for specific AO instruments and scientific targets. Such forecast is part of ALTA-2 project for LBT and potentially it can be of great help in planning AO observations to match the best atmospheric conditions and maximize the scientific throughput of a top-class telescope. In this contribution we present a preliminary evaluation of the current confidence limits of such an approach, comparing the results of PASSATA simulations to real time measurements of SR and FWHM obtained from SOUL (FLAO LBT upgrade) and SAXO (on SPHERE at Paranal). A comparison is also performed with respect to TIPTOP simulations.

Elena Masciadri, INAF-Osservatorio Astrofisico di Arcetri

Optical Turbulence Forecasts: towards a new hybrid strategy era

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.10

The OT forecast on a time scale of 1 or 2 hours (short time scales) is crucial for all kind of present and new generation instrumentation supported by adaptive optics that will be mainly operated in Service Mode. In this contribution I will summarise a few among the most recent and relevant results obtained in this context by our group and where we are going on. More precisely we undertook a hybrid approach that takes into account a synergic use of the numerical technique (atmospherical models) and statistical techniques such as autoregression/machine learning/deep learning. Our results tell us that we are able to obtain excellent performances with the two operational forecast systems we are leading: ALTA (@ LBT) and FATE (@ VLT). FATE recently as been selected winner proposal of an international Call for Tender opened by ESO aiming to provide nightly and daily forecasts of a set of astroclimatic and atmospheric parameters relevant for the VLT instrumentation. The ESO goals are: (1) to prepare the service mode of ELT by gaining experience on the use of forecast at VLT and by maximising the science return of the VLT, (2) to enable a more aggressive short term scheduling of observations with well understood risk, (3) to decrease the amount of out-of-constraint observations due to unforseen changes of atmospheric conditions. Such a hybrid approach will allow us in principle to tackle also the forecast of parameters not dependent simply on the atmosphere but also on the AO instruments specifications such as the PSF figures of merit (FWHM, SR, etc.).

Guido Agapito, INAF-Osservatorio Astrofisico di Arcetri

PASSATA and TIPTOP: simulation tools for Adaptive Optics systems in ADONI

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.11

In this work we present the status of two simulation tools for Adaptive Optics systems: PASSATA and TIPTOP. These tools have been developed mainly at Arcetri observatory and they are able to simulate a wide variety of systems. PASSATA (PyrAmid Simulator Software for Adaptive opTics Arcetri) is an IDL and CUDA based library capable of doing Monte-Carlo end-to-end simulations. It is currently used to simulate LBT SOUL, VLT ERIS and MAVIS, ELT MAORY and CaNaPy/ALASCA. TIPTOP is an analytical simulator that exploits simplifications given by the Fourier domain. It has been developed in Python by a collaboration between Laboratoire d’Astrophysique de Marseille (LAM) and INAF. TIPTOP is an early stage of development but its goals are high: integrating in the Exposure Time Calculators (ETC) for ELT instruments and VLT MAVIS, supporting observers in the choice of the Natural Guide Star asterism and working in PSF reconstruction pipelines.

Andrea Grazian, INAF-Osservatorio Astronomico di Padova

The PSF Reconstruction service for MICADO@ELT

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.12

MICADO is the first light adaptive optics instrument of ESO ELT, providing diffraction limited imaging and long-slit spectroscopy at near-infrared wavelengths. For most of the planned MICADO scientific applications, a detailed knowledge of the PSF is required. The PSF Reconstruction (PSF-R) Team of MICADO is currently developing, for the first time within all ESO telescopes, a software service devoted to the reconstruction of the instrumental PSF from telemetry data only, without accessing the scientific focal plane data themselves. The PSF-R tool will work both for data gathered with a single-conjugate natural guide star adaptive optics system (SCAO) and with a multi-conjugate laser guide star adaptive optics system (MCAO, developed by MAORY). The PSF-R service will support the state-of-the-art scientific analysis of the MICADO images and spectra, by further improving the reduction of AO data in a post processing phase. The functionalities and architecture of the PSF-R software will be highlighted in this presentation, together with an overview of the successful analysis of both MICADO simulated data and real data from the SCAO instrument SOUL at LBT. The development plan of the PSF-R service will be discussed, showing the status of the MICADO PSF-R deliverable and its readiness level. The PSF-R Team of MICADO has successfully fulfilled the Final Design Review recently, and it is ready to meet the ELT first light in 2027.

Matteo Simioni,INAF-Osservatorio Astronomico di Padova

Testing the MICADO@ELT PSF Reconstruction tool on SOUL@LBT data

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.13

A detailed knowledge of the point-spread function (PSF) is mandatory to fulfill most scientific requirements of the next generation adaptive optics (AO) instruments that will equip 30-meter class telescopes. Our blind PSF reconstructions (PSF-R) algorithm is currently being developed in the context of the MICADO@ELT consortium and it is aimed to reconstruct observation-specific PSFs without extracting information from the science data, relying only on telemetry and calibrations. After evaluating its reliability on end-to-end simulations, our PSF-R algorithm is mature enough to test it on real AO data. In this presentation we will discuss its performances and the uncertainties introduced in scientific measurements, for single-conjugated AO observations taken with the SOUL+LUCI instrument of the Large Binocular Telescope. In particular, the flexibility of our PSF-R software allowed the successful implementation of the pyramid wavefront-sensor. This is the first application of our algorithm to real data, demonstrating its readiness level and paving the way to further testing. For this reason, we focussed on observations of bright, on-axis point-like sources. By carefully calibrating the instrument response we were able to obtain a difference in Strehl ratio between the observed and the reconstructed PSFs of less than 2%. Furthermore, the full-width at half maximum of the reconstructed PSF differs less than 4.5% with respect to the observed PSF one. Finally, we will discuss a general method for performing the scientific evaluation of the reconstructed PSFs consisting of a dedicated set of simulated observations of an ideal science case. Specifically, the morphological characterization of a compact galaxy has been selected, being the typical case where a blind PSF-R approach is advantageous. The Sersic index results to be the only quantity affected by the use of the reconstructed PSF. Still, its measured deviation from the true value is small enough to allow the correct classification of the simulated galaxy

Roberto Biasi, Matteo Tintori, Microgate S.r.l., A.D.S. International S.r.l.

Large, contactless deformable mirrors technology: past, present and future

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.14

Andrea Baruffolo, INAF-Osservatorio Astronomico di Padova

Preliminary Design of the MAORY@ELT Real-Time Computer

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.15

In this paper we report about the preliminary design of the Real Time Computer (RTC) for the MAORY@ELT Multi-Conjugate Adaptive Optics module for the ESO Extremely Large Telescope. The ELT MCAO module provides high sky coverage, large field, diffraction limited correction in the near infrared. It relies on the use of a constellation of six Laser Guide Stars (LGS) and up to three Natural Guide Stars (NGS) for tomographic atmospheric turbulence sensing, and multiple mirrors (ELT M4 and up to two post-focal deformable mirrors) for correction. In particular, we will discuss the overall RTC architecture, the main control strategy, including provision for vibrations compensation, auxiliary loops and tasks for optimization of correction. We will also briefly describe our product and quality assurance plans

Lorenzo Cabona, INAF-Osservatorio Astronomico di Padova

Continuous photo-controlled deformable mirror based on silicon photoconductor

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.16

The fabrication and characterization of a Silicon based photo-controlled deformable mirror (PCDM) for spatial light modulation and wavefront control is reported. The device is a 1-inch clear aperture membrane mirror (5 μm thick nitrocellulose membrane) coupled with a 1-inch monolithic non-pixelated Silicon photoconductive slab. A transparent ITO electrode is deposited on one side of the Silicon substrate. The device is electrically driven in AC and it is characterized by measuring the generated wavefront using a Shack-Hartmann sensor. The uniform illumination with a NIR LED induces a membrane deformation that increases with the applied voltage, its frequency and the light irradiance. The maximum deformation achieved is approximately 2 μm PtV (wavefront). The repeatability is tested confirming the reliability od th device. Concerning the time stability, this property is maintained in a timeframe suitable for this kind of devices. A response time of about 10 ms is measured. The device is suitable for an efficient adaptable focusing element with an important focus control.

Runa Antonio Briguglio Pellegrino, INAF-Osservatorio Astrofisico di Arcetri

Optical Calibration of Deformable Mirrors

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.17

Mariarita Murabito, INAF-Osservatorio Astronomico di Capodimonte

Small-scale magnetic features as science drivers for high-resolution solar observations

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.18

Mixed-polarity magnetic fields in the same resolution element of bi-dimensional solar images are known to produce an artificial magnetic flux cancellation. This effect often prevents us from investigating the rich dynamics of small-scale magnetic flux concentrations revealed by the sharpest observations of the solar atmosphere. In this contribution, we report on a selection of science cases that can take advantage of diffraction-limited facilities equipped with adaptive optics in the context of solar observations, like the evolution of quiet-Sun magnetic elements and the fine structure of sunspot umbrae and penumbrae.

Giorgio Viavattene, INAF-Osservatorio Astronomico di Roma

Splitting the pupil plane for large WF sensors

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.19

The 4-m class European Solar Telescope (EST) shall be provided with powerful MCAO to achieve the required > 80 arcsec corrected FoV. The EST MCAO system shall use large format high speed WFS detectors running at up to 2 kHz. We present a possible solution for multiplexing the wavefront sensing by splitting the pupil plane on two or more detectors that sample different regions of the pupil plane. We report on the results of laboratory tests of a multiplexed SH-WFS demonstrator realized at the Optical Laboratory of the INAF-OAR for the H2020 SOLARNET project. We describe its optical layout, based on two CMOS EoSens 3CXP cameras with a “true” Thorlabs SH-WFS, and a possible evolution of this concept based on the latest CMOS technology.

Michele Punturo, INFN – Sezione di Perugia

Einstein Telescope: status of the project and the collaboration

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.20

Mirko Colapietro, INAF-Osservatorio Astronomico di Capodimonte

A PLC-based control system for the AO module of MAVIS

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.21

MAVIS (MCAO Assisted Visible Imager and Spectrograph) is a new instrument for the Adaptive Optics Facility (AOF) of the ESO VLT-UT4. It will consist of a multi-conjugate Adaptive Optics Module (AOM) that will feed an imager, a spectrograph and a possible third instrument, all operating in the visible band.
The MAVIS AOM will include several motorized functions that will be managed by a PLC-based control system, following the ESO standards, characterized by a modular architecture to ensure high reliability and maintainability of the system and simplify the integration activities foreseen in different sites.
The list of actuators will include also some tracking devices (e.g. a K-mirror and NGS XY positioning stages) for which a prototyping activity has been envisaged during the design phases.
This poster shows the current design of the MAVIS AOM instrument control electronics and some preliminary tests already carried out on tracking devices.

Bernardo Salasnich, INAF-Osservatorio Astronomico di Padova

Control Software for AO instruments: similarities and differences among ongoing INAF-OAPd projects

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.22

At INAF OAPd we participate in more than one project for ground based astronomical instrumentation. In particular, we have the responsibility for the Control Software work-package of ERIS and MAVIS for ESO’s VLT, SHARK-NIR for LBT and MAORY for ESO’s ELT. All these instruments include its own adaptive optics module and/or use the AO facilities provided by the hosting observatory. MAORY probably represents the extreme case being a huge AO module and not a scientific instrument. All these projects are at different development phases: ERIS commissioning is ongoing in these months, SHARK-NIR terminated the integration and just passed the acceptance in Europe, MAORY had the preliminary design review last year and MAVIS’s one is scheduled by the end of this year.
All these projects use Control Software based on different technologies. In this paper we first give an overview of the projects, we present the current status of the control SW, show the similarities of the SW architectures and the main differences in the AO. Finally we highlight the main difficulties and challenges we encountered so far.

Igor Coretti and Antonio Sulich, INAF-Osservatorio Astronomico di Trieste

PLC-based control systems

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.23

I PLC (Programmable Logic Controller) sono dispositivi di controllo ampiamente utilizzati nel mondo dell’automazione industriale, che stanno trovando diffusione sempre più ampia anche nel mondo della strumentazione astronomica. In questo tutorial verrà fatta una breve introduzione a questi dispositivi, con particolare riferimento alla linea Beckhoff, correntemente utilizzati nei progetti ESO. La semplicità e versatilità d’uso di questi componenti può essere però sfruttata anche all’infuori di questo ambito, per altri compiti di automazione in laboratorio o banco di misura. Verranno illustrati i concetti base ed i componenti essenziali con una veloce escursione dell’ambiente di sviluppo. Descriveremo il flusso di lavoro tipico, prendendo come esempio qualche device tra quelli più spesso utilizzati nella strumentazione astronomica, seguito da una dimostrazione pratica.

Simone Di Filippo, INAF-Osservatorio Astronomico di Padova

The Ingot Wavefront Sensor: general updates and lab activities

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.24

I PLC (Programmable Logic Controller) sono dispositivi di controllo ampiamente utilizzati nel mondo dell’automazione industriale, che stanno trovando diffusione sempre più ampia anche nel mondo della strumentazione astronomica. In questo tutorial verrà fatta una breve introduzione a questi dispositivi, con particolare riferimento alla linea Beckhoff, correntemente utilizzati nei progetti ESO. La semplicità e versatilità d’uso di questi componenti può essere però sfruttata anche all’infuori di questo ambito, per altri compiti di automazione in laboratorio o banco di misura. Verranno illustrati i concetti base ed i componenti essenziali con una veloce escursione dell’ambiente di sviluppo. Descriveremo il flusso di lavoro tipico, prendendo come esempio qualche device tra quelli più spesso utilizzati nella strumentazione astronomica, seguito da una dimostrazione pratica.

Gianluca Li Causi, INAF-Osservatorio Astronomico di Roma
MFBD and IFT data modeling for high-resolution high-contrast imaging

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.25

In the context of high-contrast imaging of exoplanets in the visible band through extreme adaptive optics, the forthcoming SHARK-VIS imager for the LBT implements the concept of high-cadence imaging at millisecond frame rate, thanks to a low noise sCMOS camera that freezes the evolution of the AO residual speckles. This allows the simultaneous exploitation of both spatial and temporal information contained in the data, by means of new algorithms that we are investigating for pushing the contrast to the theoretical noise limit and achieving diffraction-limited resolution, with the final goal of detecting very faint planets at a few lambda/D separation from their host star. These algorithms do not perform a data reduction, instead they leverage on a forward data modeling of the image formation and acquisition process to reconstruct the astronomical source. I will describe and discuss two mathematical methods that we applied to real data sequences, namely the Kraken Multi-Frame Blind Deconvolution (MFBD), and the Information Field Theory (IFT).

Giorgio Viavattene, INAF-Osservatorio Astronomico di Roma
Integral Field Units (IFU) for AO focal plane: the case study of ELVIS, the new IFU for SHARK-VIS

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.26

ELVIS (Exoplanets at LBT with a Visible IFS for Shark-vis) is an add-on Integral Field Unit (IFU) to be integrated in the new LBT high-contrast high-resolution AO-assisted imager SHARK-VIS. The spectrograph, which provides a spectral resolution of 10-20k at H-alpha is fed by fiber bundles with at least 12×12 spaxels. This configuration, thanks to an optimized VPH dispersing element designed and made in INAF, allows for a very compact design that can be housed in a 19” rack unit. The preliminary optical design of this spectrograph, based on spherical lenses, is diffraction limited on the operational spectral range. Here we present different optical solutions we have investigated to increase the efficiency of the fiber bundle, comparing different approaches such as direct light injection, lenslet arrays or BIGRE arrays. Finally, we show preliminary results of laboratory tests for the proposed solutions with comparative tests between fiber IFU technologies and the alternative approach with a direct BIGRE focal plane segmentation.

Michele Frangiamore, Michele Frangiamore
INNOVATIVE VPH GRATINGS FOR ELVIS (Exoplanet LBT Visible Imaging Spectrograph)

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.27

The Exoplanet LBT Visible Imaging Spectrograph (ELVIS) embedded into the high contrast and resolution AO-assisted imager SHARK-VIS at Large Binocular Telescope 2 x 8.4m (LBT) is an upgrade of existing Integral Field Unit (IFU) to permit e newer comprehension of young accreting substellar and planetary companions with higher contrast (up to 10-5) in their H-alpha emission with respect to standard imagers.
ELVIS performances are strongly related to the dispersing element. Using a classical single channel Volume Phase Holographic Gratings (VPHG), the light is smeared out in a single spectrum. For covering large bandwidths at a certain resolving power, ELVIS will need a very wide detectors. Our approach to this issue is to Multiplex the VPHGs (M-VPHGs). Instead of having a single grating we use multiple gratings stacked together in a single piece of glass. Each grating diffracts different target spectral ranges toward the same direction mimicking an echellette spectrograph. The result is a combination of a wider spectral range together with a higher resolution. The M-VPHGs will be manufactured using high performance holographic materials (Bayfol®HX) by COVESTRO AG. A feasibility study in the case of ELVIS will be carried out starting from the instrument requirements. Such innovative approach is more general and it could be applied to other AO fed spectrographs working both in the visible and infrared, such as Medres for SPHERE+, Vis-X for MagAO-X.

Fernando Pedichini, INAF-Osservatorio Astronomico di Roma

IS THERE (ALWAYS) A BETTER DETECTOR IN THE FAST WORLD OF AO?

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.28

This short, not fully extensive, review presents some cases where the “correct” choose for the detector may do the difference at least on the project budget. Typical cases of night and solar AO astronomy are the test benchmark where we compare off-the-shelf detector performances with respect to the “ideal one” to derive selection and test criteria useful for both science and wave-front focal planes. RYXEL, the new ESO’s software for the simulation of existing and future generation of detectors, will help
AO scientists in searching for their dream detector.

Alessandro Terreri, INAF-Osservatorio Astronomico di Roma
Neural Networks and PCA coefficients to identify and correct aberrations in Adaptive Optics

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.29

Static and quasi-static aberrations represent a great limit for high contrast imaging in large telescopes. Among them the most important ones are all the aberrations not corrected by Adaptive Optics (AO) system, called Non-Common Path Aberrations (NCPA).
An estimate of the NCPA can be obtained by a trial-and-error approach or by more sophisticated techniques of focal plane wavefront sensing.
In all cases, a fast procedure is desirable to limit the telescope downtime and to repeat, if needed, the correction procedure to cope with the temporal variation of the NCPA.
In this work, through simulated images, I will describe the application of a supervised NN for the mitigation of NCPA in high contrast imaging at visible wavelengths and I will apply this method to fast imagers such as SHARK-VIS, the forthcoming visible band high-contrast imager for LBT.
Preliminary results show a measurement accuracy of the NCPA of 2 nm RMS for each sensed Zernike mode in turbulence-free conditions, and 5 nm RMS per mode in presence of a residual turbulence corresponding to a WFE=42.5 nm RMS, a typical value during LBT AO system calibration. This measurement accuracy is sufficient to guarantee that, after correction, NCPA residuals in the system are negligible compared to the typical WFE >100 nm RMS of the best AO systems at large telescopes.
Our simulations show this method is robust even in the presence of turbulence-induced aberrations that are not labelled in the training phase of the NN.

Claudio Arena, INAF-Osservatorio Astrofisico di Catania

Design of a Fine Guidance System for a high stability Low-Earth Orbit Mission

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.30

Astronomical space missions require stable and fast target pointing to achieve their science objectives. To obtain high pointing stability, a Fine Guidance System (FGS) mechanism is used to provide fine pointing control.
We developed a proof of concept FGS using piezoelectric actuators. Such a system allows for an FGS exhibiting stable pointing and fast, reliable operation.
An optical setup was designed and built to test the novel mechanism. The mechanical and thermal characteristics of the system were also studied using finite elements analysis.
A software simulator was developed to study the performance of the FGS mechanism in a possible high stability spectroscopy mission.
With such a proof of concept, we showed that a reliable and fast operating FGS can be implemented using piezoelectric actuators. This would allow future astronomy missions to reach a stability of 5–10 milli-arcsec at a correction rate of up to a few hundred hertz. This stability, together with other advantages such as the mechanical simplicity of the system, would make it ideal for many low Earth orbit satellites, for which many orbital disturbances need to be managed.

Runa Antonio Briguglio Pellegrino, INAF-Osservatorio Astrofisico di Arcetri
Adaptive Optics for future space telescopes: the SPLATT way

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.31

At INAF, the expertise matured during the development and testing of large format adaptive mirrors (e.g. LBT, VLT, M4) has been successfully transferred to space active optics during the LATT activities, which was an ESA technological research project with the goal to demonstrate a 40 cm diameter active primary controlled by 19 voice coil actuators. Recently, a follow-up has been proposed and funded with a TECNO-PRIN INAF. The new SPLATT project aims at investigating two main aspects in the context of space active optics: as first, the rejection of the external disturbances, offered “for free” by voice coil, contactless, actuators; secondarily, the sensitivity of a pyramid Wavefront sensor to achieve sub-nanometer correction stability for high contrast.
In the talk I will present the main concepts behind the project and the outputs of the laboratory and simulation activities in Arcetri.

Adriano Fontana, INAF-Osservatorio Astronomico di Roma
STILES – Strengthening the Italian Leadership in ELT and SKA

DOI: https://doi.org/10.36116/VIDEOMEM_1.2022.32

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