Design of an IR Imaging Channel for the Keck Observatory SCALES Instrument

TL;DR

This paper details the design and evaluation of a thermal infrared imaging channel for the upcoming SCALES instrument at Keck Observatory, aimed at exoplanet imaging and characterization.

Contribution

It introduces the optomechanical design of the imaging channel and assesses its capabilities for high-resolution infrared imaging in a next-generation spectrograph.

Findings

Designed an imaging channel with 12"x12" FOV and low distortion.

Evaluated the optical performance and throughput of the imager.

Supports high-resolution imaging and alignment for exoplanet studies.

Abstract

A next-generation instrument named, Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES), is being planned for the W. M. Keck Observatory. SCALES will have an integral field spectrograph (IFS) and a diffraction-limited imaging channel to discover and spectrally characterize the directly imaged exoplanets. Operating at thermal infrared wavelengths (1-5 micron, and a goal of 0.6-5 micron), the imaging channel of the SCALES is designed to cover a 12"x 12" field of view with low distortions and high throughput. Apart from expanding the mid-infrared science cases and providing a potential upgrade/alternative for the NIRC2, the H2RG detector of the imaging channel can take high-resolution images of the pupil to aid the alignment process.Further, the imaging camera would also assist in small field acquisition for the IFS arm. In this work, we present the optomechanical design of the imager and evaluate its capabilities and performances.