A new broadband atmospheric dispersion corrector for HROS-TMT

TL;DR

This paper introduces a novel broadband atmospheric dispersion corrector (RADC) for the HROS-TMT, utilizing optimized Amici prisms and a custom model to improve image quality and fiber coupling efficiency across 0.31-1 micron wavelengths.

Contribution

It presents a new optical design for a broadband atmospheric dispersion corrector using Amici prisms and a custom model implementation in Zemax for the HROS-TMT.

Findings

Effective correction of atmospheric dispersion across 0.31-1 micron range.

High transmission efficiency (>90%) of the Amici prisms.

First implementation of Filippenko model in Zemax via DLL.

Abstract

Atmospheric dispersion causes light from celestial objects with different wavelengths to refract at varying angles as it passes through Earth's atmosphere. This effect results in an elongated image at the focal plane of a telescope and diminishes fiber coupling efficiency into spectrographs. We propose an optical design that incorporates a Rotational Atmospheric Dispersion Corrector (RADC) to address the broadband dispersion encountered in the multi-object mode of the High-Resolution Optical Spectrograph (HROS) on the Thirty Meter Telescope (TMT). The RADC corrects the dispersion across the entire wavelength range (0.31-1 micron), using Amici prisms optimized for over 90% transmission efficiency and minimal angular deviation of the beam from the optical axis after dispersion correction. For enhanced accuracy, particularly in the blue region, we have, for the first time, implemented the Filippenko (1982) model in Zemax via a custom Dynamic-Link Library (DLL) file.