The MICADO first light imager for the ELT: preliminary design of the MICADO Calibration Assembly

Ground-Based and Airborne Instrumentation for Astronomy VII

Riechert

et al. 2018

Self Cite

We report on our ongoing efforts to ensure that the MICADO NIR imager reaches differential absolute (often abbreviated: relative) astrometric performance limited by the SNR of typical observations. The exceptional 39m diameter collecting area in combination with a powerful multi-conjugate adaptive optics system (called MAORY) brings the nominal centroiding error, which scales as FWHM/SNR, down to a few 10 µas. Here we show that an exceptional effort is needed to provide a system which delivers adequate and calibrateable astrometric performance over the full field of view (up to 53 arcsec diameter).

Section: Instrumental Linear-term Controlmentioning

confidence: 99%

Section: Micado Astrometry Fundamental Limits -Scale: 002 Arcsecmentioning

confidence: 99%

The MICADO first light imager for ELT: its astrometric performance

Pott

Ground-Based and Airborne Instrumentation for Astronomy VII

Riechert

et al. 2018

Self Cite

Development of the Warm Astrometric Mask for MICADO Astrometry Calibration

Sawczuck

Pott

et al. 2019

PASP

The achievement of µarcsec relative astrometry with ground-based, near infrared, extremely large telescopes requires a significant endeavour of calibration strategies. In this paper we address the removal of instrument optical distortions coming from the ELT first light instrument MICADO and its adaptive optics system MAORY by means of an astrometric calibration mask. The results of the test campaign on a prototype mask (scale 1:2) has probed the manufacturing precision down to ∼ 50nm/1mm scale, leading to a relative precision δσ ∼ 5e − 5. The assessed manufacturing precision indicates that an astrometric relative precision of δσ ∼ 5e − 5 = 50µas 1ar csec is in principle achievable, disclosing µarcsec near infrared astrometry behind an extremely large telescope. The impact of ∼ 10-100 nm error residuals on the mask pinholes position is tolerable at a calibration level as confirmed by ray tracing simulations of realistic MICADO distortion patterns affected by mid spatial frequencies residuals. We demonstrated that the MICADO astrometric precision of 50 µas is achievable also in presence of a mid spatial frequencies pattern and manufacturing errors of the WAM by fitting the distorted WAM pattern seen through the instrument with a 10 th order Legendre polynomial.

Development of the MICADO Flat-field and Wavelength Calibration Unit: From Design to Prototyping

Häberle

Sauter

et al. 2020

PASP

Self Cite

We describe the evolution and the analysis of the design that led to the development of the Flat-field and wavelength Calibration Unit (FCU) for the Multi-AO Imaging CAmera for Deep Observations (MICADO) instrument. MICADO will be one of the first light instruments of the Extremely Large Telescope. The FCU challenge in terms of calibration is related to the large size of the MICADO entrance and final focal plane, ∼200 mm×200 mm. Such a focal plane scale and its segmentation in 3×3 detectors, require significant design modifications with respect to the calibration units of the current and past generation of instruments. The design analysis and ray tracing calculations are complemented with the test and verification of lab prototypes to assess the reliability of the FCU architecture in terms of flat-field illumination uniformity and signal to noise, spectral calibration line coverage and radial velocity stability of the wavelength solution provided to the instrument.