Optical design of the SOXS spectrograph for ESO NTT

TL;DR

This paper details the optical design of the SOXS spectrograph for ESO NTT, highlighting its innovative features, optical components, and expected performance for wideband, medium-resolution spectroscopy.

Contribution

It presents the comprehensive optical design of SOXS, including novel UV-VIS grating technology and the application of the 4C design for NIR, preparing for the final design review.

Findings

Optical design achieves high throughput and spectral quality.

Innovative UV-VIS gratings improve efficiency.

Design readiness for final review and deployment.

Abstract

An overview of the optical design for the SOXS spectrograph is presented. SOXS (Son Of X-Shooter) is the new wideband, medium resolution (R>4500) spectrograph for the ESO 3.58m NTT telescope expected to start observations in 2021 at La Silla. The spectroscopic capabilities of SOXS are assured by two different arms. The UV-VIS (350-850 nm) arm is based on a novel concept that adopts the use of 4 ion-etched high efficiency transmission gratings. The NIR (800- 2000 nm) arm adopts the '4C' design (Collimator Correction of Camera Chromatism) successfully applied in X-Shooter. Other optical sub-systems are the imaging Acquisition Camera, the Calibration Unit and a pre-slit Common Path. We describe the optical design of the five sub-systems and report their performance in terms of spectral format, throughput and optical quality. This work is part of a series of contributions describing the SOXS design and properties as it is about to face the Final Design Review.