PDS Powered Optics RFI/CFT

The PDS (Phasing and Diagnostic Station), will be installed in the Prefocal Station of the next generation Telescope developed by ESO – the Extremely Large Telescope (ELT) – that includes a 39m segmented primary mirror (M1). The ELT is located in the Antofagasta Region in northern Chile, 120 km from Antofagasta city and 20 km from ESO’s Paranal Observatory. The PDS is the tool that helps to commission the telescope in terms of wavefront control and telescope verification and its functions span from phasing the segmented M1 to telescope diagnostics and verification tasks, using various wavefront and phasing sensors in order to ensure the telescope performances throughout its lifetime, currently set to 30 years (goal: 50 years). To condition the optical beam for the individual need of the several wavefront sensors, powered optics are designed and we are now in the process of purchase. The present document outlines the general technical specifications, and draft statement of work for the procurement of the powered optics for the PDS. After an internal review process, the PDS optics design has been updated as well as its procurement strategy. Compared to the initial RFI of 2020, which was carried out in the preliminary design phase of the project, ESO will now purchase the individual types of optics separately in 8 contracts. This RFI, followed by the CFT, covers the powered optics part, hence all lenses are mounted in barrels. Those lens barrels are used in an on-axis configuration, covering a relatively small field of 12 arcsec (see also Annex A with the angle of incidence column). The current RFI comprises a total of 28 all spherical lenses, mounted in doublets in suitable lens barrels. The overview and exact details of the optical elements can be found on AD1 and in Annex A of this document. The lenses are grouped by sub-systems and are required to be delivered mounted in barrels.