A Fourier optics approach to evaluate the astrometric performance of MICADO

Born, Joost van den; Jellema, Willem; Navarro, Ramón; Tolstoy, Eline; Jayawardhana, Bayu; Janssen, A.

doi:10.1117/12.2560912

Cited by 2 publications

(1 citation statement)

References 15 publications

(15 reference statements)

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“…35 Since the AO correction cannot reach this system, we do not analyze its distortions. Nevertheless, the distortion variations are expected to be very small since the imaging astrometric channel has no moving parts with the exception of the ADC, which is kept fixed during the exposure and can be calibrated out with a preobservation calibration 36 and with its optomechanics being immersed in a thermalized cryoenvironment. 37 4 Mid-Spatial Frequency Challenge…”

Section: Low-order Distortions and Plate Scale Driftsmentioning

confidence: 99%

Performance and limitations of using ELT and MCAO for 50 μas astrometry

Rodeghiero

Arcidiacono

Pott

et al. 2021

J. Astron. Telesc. Instrum. Syst.

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Multi-conjugated adaptive optics (MCAO) is essential for performing astrometry with the Extremely Large Telescope (ELT). Unlike most of the 8-m class telescopes, the ELT will be a fully adaptive telescope, and a significant portion of the adaptive optics (AO) dynamic range will be depleted by the correction and stabilization of the telescope aberrations and instabilities. MCAO systems are of particular interest for ground-based astrometry since they stabilize the low-order field distortions and transient plate scale instabilities, which originate from the telescope and in the instrument. All instruments have several optical elements relatively far away from the pupil that can potentially challenge the astrometric precision of the observations with their residual mid-spatial frequencies errors. Using a combined simulation of ray tracing and AO numerical codes, we assess the impact of these systematic errors at different field-ofview (FoV) scales and fitting scenarios. The distortions have been assessed at different sky position angles (PA) and indicate that over large FoVs only small PA ranges (AE1 deg to 3 deg) are accessible with astrometric residuals ≤50 μas. A full compliance with the astrometric requirement, at any PA, is achievable for 2 arc sec 2 FoV patches already with a third-order polynomial. The natural partition of the optical system into three segments, i.e., the ELT, the MAORY MCAO module, and the MICADO instrument, resembles a splitting of the astrometric problem into the three subsystems that are characterized by different distortion amplitudes and calibration strategies. The result is a family portrait of the different optical segments with their specifications, dynamic motions, conjugation height, and AO correctability, leading to tracing their role in the bigger puzzle of the 50-μas as astrometric endeavor. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Low-order Distortions and Plate Scale Driftsmentioning

confidence: 99%

Performance and limitations of using ELT and MCAO for 50 μas astrometry

Rodeghiero

Arcidiacono

Pott

et al. 2021

J. Astron. Telesc. Instrum. Syst.

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The MICADO atmospheric dispersion corrector: optomechanical design, expected performance and calibration techniques

Born

Romp

Janssen

et al. 2022

Ground-Based and Airborne Instrumentation for Astronomy IX

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The differential refraction of light passing through the atmosphere can have a severe impact on image quality if no atmospheric dispersion corrector (ADC) is used. For the Extremely Large Telescope (ELT) this holds true well into the infrared. MICADO, the near-infrared imaging camera for the ELT, will employ a cryogenic ADC consisting of two counter-rotating Amici prisms with diameters of 125 mm. The mechanism will reduce the atmospheric dispersion to below 2.5 milli arcseconds (mas), with a set goal of 1 mas. In this report, we provide an overview of the current status of the ADC in development for MICADO. We summarise the optomechanical design and discuss how the cryogenic environment impacts the performance. We will also discuss our plan to use a diffraction mask in the cold pupil to calibrate and validate the performance once the instrument is fully integrated.

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A Fourier optics approach to evaluate the astrometric performance of MICADO

Cited by 2 publications

References 15 publications

Performance and limitations of using ELT and MCAO for 50 μas astrometry

Performance and limitations of using ELT and MCAO for 50 μas astrometry

The MICADO atmospheric dispersion corrector: optomechanical design, expected performance and calibration techniques

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