SCALES for Keck: Optical Design

TL;DR

SCALES is a sophisticated infrared instrument for Keck Observatory, combining high-contrast imaging and spectroscopy over a broad wavelength range with innovative optical design and performance modeling.

Contribution

This paper presents the complete optical design, performance analysis, and manufacturing considerations for the SCALES instrument, a novel high-contrast infrared imager and spectrograph.

Findings

Successful diffraction-limited imaging over 1.0-5.0 microns

Effective low and moderate spectral resolution capabilities

Comprehensive performance modeling and manufacturing insights

Abstract

SCALES is a high-contrast, infrared coronagraphic imager and integral field spectrograph (IFS) to be deployed behind the W.M. Keck Observatory adaptive optics system. A reflective optical design allows diffraction-limited imaging over a large wavelength range (1.0 - 5.0 microns). A microlens array-based IFS coupled with a lenslet reformatter ("slenslit") allow spectroscopy at both low (R = 35 - 250) and moderate (R = 2000 - 6500) spectral resolutions. The large wavelength range, diffraction-limited performance, high contrast coronagraphy and cryogenic operation present a unique optical design challenge. We present the full SCALES optical design, including performance modeling and analysis and manufacturing.