MAORY is one of the approved instruments for the European Extremely Large Telescope. It is an adaptive optics module, enabling high-angular resolution observations in the near infrared by real-time compensation of the wavefront distortions due to atmospheric turbulence and other disturbances such as wind action on the telescope. An overview of the instrument design is given in this paper.
The Natural Guide Star (NGS) Wavefront Sensor (WFS) sub-system of MAORY implements 3 Low-Order and Reference (LOR) WFS needed by the Multi-Conjugate Adaptive Optics (MCAO) system. Each LOR WFS has 2 main purposes: first, to sense the fast low-order modes that are affected by atmospheric anisoplanatism and second, to de-trend the LGS measurements from the slow spatial and temporal drifts of the Sodium layer. These features require to implement 2 different WFS sharing the same NGS and optical breadboard but being respectively a 2×2 Shack-Hartman Sensor (SHS) working at infrared wavelengths and a slow 10×10 SHS at visible bands. The NG WFS sub-system also provides a common support plate for the 3 WFS and their control electronics and cabling. The paper summarizes the status of the preliminary design of the LOR Module on the road to the MAORY Preliminary Design Review (PDR), focusing mainly on the description and analysis of the opto-mechanical arrangement foreseen for the NGS WFS sub-system. Performances and the design trade-offs of the NGS WFS sub-system are analyzed in a complementary paper. First, the requirement imposed by MAORY AO system are discussed. Then the paper gives an overview of the opto-mechanical arrangement for the main components of the sub-system: the support plate, the 3 WFS units and their interfaces to the instrument rotator. In the end the paper discusses the sub-system pointing and WFE budgets derived from different analyses. The design concept for the electronic devices of the sub-system, the cabinet arrangement and the cabling sheme are given in second complementary paper.
The LOR WFS module will provide low and medium order sensing for the MAORY MCAO mode. It is composed of three identical units, hosting two Shack-Hartmann wavefront sensors each: an infrared 2×2 sub-apertures, used for low order modes, and a visible 10×10 sub-apertures for the slow truth sensing needed to correct the LGS WFS measurements. In this paper we show the current design of the NGS WFS control electronics and the interfaces with the MICADO instrument.
The Calibration Unit (CU) is a subsystem of the Enhanced Resolution Imager and Spectrograph (ERIS), the newgeneration instrument for the Cassegrain focus of the ESO UT4/VLT, aimed at performing AO-assisted imaging and medium resolution spectroscopy in the 1-5 micron wavelength range. The ERIS-CU is aimed to providing both focal plane artificial sources and uniform illumination over the 0.4 - 2.4 micron wavelengh range, for purposes of calibration and technical check of the SPIFFIER spectrograph, the NIX camera and the AO Module. Some challenging aspects emerged during the detailed design phase, mainly related to the need to cover such a broad wavelength range while ensuring adequate photon rates, excellent image quality and high Strehl. The technical solutions adopted to achieve the final design goals are presented and their implementation during the construction phase are shown and discussed.