An original image slicer designed for Integral Field Spectroscopy with NIRSpec/JSWT

TL;DR

This paper introduces a novel fan-shaped image slicer design for Integral Field Spectroscopy with NIRSpec/JSWT, significantly reducing optical aberrations and improving image quality over classical slicers.

Contribution

The paper presents an original fan-shaped image slicer design that minimizes aberrations and enhances image quality for IFS instruments like NIRSpec/JSWT.

Findings

Wavefront error reduced by a factor of 2

Negligible differential aberration across the field

Design successfully applied to NIRSPEC/IFU

Abstract

Integral Field Spectroscopy (IFS) provides a spectrum simultaneously for each spatial sample of an extended, two-dimensional field. It consists of an Integral Field Unit (IFU) which slices and re-arranges the initial field along the entrance slit of a spectrograph. This article presents an original design of IFU based on the advanced image slicer concept. To reduce optical aberrations, pupil and slit mirrors are disposed in a fan-shaped configuration that means that angles between incident and reflected beams on each elements are minimized. The fan-shaped image slicer improves image quality in terms of wavefront error by a factor 2 comparing with classical image slicer and, furthermore it guaranties a negligible level of differential aberration in the field. As an exemple, we are presenting the design LAM used for its proposal at the NIRSPEC/IFU invitation of tender.