SOXS NIR: Optomechanical integration and alignment, optical performance verification before full instrument assembly

TL;DR

This paper details the opto-mechanical integration, alignment, and optical performance verification of the NIR arm of the SOXS instrument, a spectrograph for the ESO-NTT telescope, ensuring readiness for full assembly.

Contribution

It introduces the integration and alignment methods for the NIR arm and verifies its optical performance prior to full instrument assembly.

Findings

Successful integration and alignment of the NIR arm components.

Verification of image quality and spectral resolving power across the NIR range.

Preparation for full instrument assembly and acceptance testing in 2024.

Abstract

This paper presents the opto-mechanical integration and alignment, functional and optical performance verification of the NIR arm of Son Of X-Shooter (SOXS) instrument. SOXS will be a single object spectroscopic facility for the ESO-NTT 3.6-m telescope, made by two arms high efficiency spectrographs, able to cover the spectral range 350 2050 nm with a mean resolving power R~4500. In particular the NIR arm is a cryogenic echelle cross-dispersed spectrograph spanning the 780-2050 nm range. We describe the integration and alignment method performed to assemble the different opto-mechanical elements and their installation on the NIR vacuum vessel, which mostly relies on mechanical characterization. The tests done to assess the image quality, linear dispersion and orders trace in laboratory conditions are summarized. The full optical performance verification, namely echellogram format, image quality and resulting spectral resolving power in the whole NIR arm (optical path and science detector) is detailed. Such verification is one of the most relevant prerequisites for the subsequent full instrument assembly and provisional acceptance in Europe milestone, foreseen in 2024.