RISTRETTO: Manufacturing of a single-mode visible high resolution spectrograph

TL;DR

The paper details the design and manufacturing status of RISTRETTO's high-resolution spectrograph, aimed at exoplanet detection via high contrast imaging and Doppler spectroscopy, with a focus on its technical specifications and thermal performance.

Contribution

It presents the final design and manufacturing progress of a high-resolution, compact spectrograph for exoplanet characterization, tailored for VLT installation.

Findings

Spectrograph resolution of 130,000 in 620-840 nm band

Successful thermal enclosure performance

Design similarities with HARPS and ESPRESSO

Abstract

The Spectrograph of the RISTRETTO instrument is now currently being manufactured. RISTETTO is an instrument designed to detect and characterize the reflected light of nearby exoplanets. It combines high contrast imaging and high resolution spectroscopy to detect the light of exoplanets. The high resolution spectrograph subject of this paper uses the doppler effect to disentangle the planetary signal from the stellar light leaks. In this paper we describe the final design of the spectrograph and report the status of its construction. The RISTRETTO spectrograph has seven diffraction limited spaxels. The spectrograph's resolution is 130000 in the 620-840 nm band. It is designed in a similar way as HARPS and ESPRESSO, being a warm, thermally controlled spectrograph under vacuum. It is designed to be compact and self contained so that it could be installed on different telescopes. It is however tailored to be installed on a nasmyth platform of a VLT telescope. We present updates to the design and the manufacturing of the instrument. In particular we present the performance of the thermal enclosure.