Upgrade of the Veloce high-resolution spectrograph at the Anglo-Australian Telescope

The Veloce spectrograph is a high resolution (R > 75000), compact, highly-stabilised, and hyper-calibrated echelle spectrograph to obtain Doppler velocities for Sun-like and M-dwarf at < 1 ms⁻¹.This spectrograph was built utilising multiple innovations to provide a “just -enough-stabilisation” platform, compensating the science observations with simultaneous collected data from an ultra-stabilised calibration source.The spectrograph consists of three spectral arms, one of which has been in operation while the additional two arms were undergoing construction.The first arm of the spectrograph, the Rosso arm, has a wavelength coverage of 580-930 nm was installed at the Anglo-Australian Telescope (AAT) and saw first light in September 2018.The Verde, 434-593 nm, and Azzurro, 378-437 nm, spectral arms passed the final design review in February of 2021 and were installed May and June of 2023 with first light occurring in early July 2023.This paper presents a review of the upgrade project along with discussions on the mechanical and optical designs in terms of procurement and manufacturability.We discuss the changes to the instrument driven from the lessons learned during the construction of the first arm of the spectrograph including detector electronics, optical mounts, and infrastructure, also the provisional acceptance of the installed instrument.We also include a discussion on the determination of the very tight slope error tolerances for the aspheric lenses in order to limit the influence of the mid-spatial frequencies on the spectra presented to the detector.