DOTIFS: fore-optics and calibration unit design

TL;DR

This paper details the design of the fore-optics and calibration unit for the DOTIFS instrument, focusing on optical modifications, calibration sources, and system compactness for improved spectroscopic performance.

Contribution

It introduces a novel combined fore-optics and calibration unit design that enhances system compactness and calibration accuracy for the DOTIFS instrument.

Findings

Design achieves telecentric beam delivery to IFUs.

Shared lenses reduce system size and complexity.

Calibration scheme ensures accurate wavelength calibration.

Abstract

We present fore-optics and calibration unit design of Devasthal Optical Telescope Integral Field Spectrograph (DOTIFS). DOTIFS fore-optics is designed to modify the focal ratio of the light and to match its plate scale to the physical size of Integral Field Units (IFUs). The fore-optics also delivers a telecentric beam to the IFUs on the telescope focal plane. There is a calibration unit part of which is combined with the fore-optics to have a light and compact system. We use Xenon-arc lamp as a continuum source and Krypton/Mercury-Neon lamps as wavelength calibration sources. Fore-optics and calibration unit shares two optical lenses to maintain compactness of the overall subsystem. Here we present optical and opto-mechanical design of the calibration unit and fore-optics as well as calibration scheme of DOTIFS.