DOTIFS: spectrograph optical and opto-mechanical design

TL;DR

DOTIFS is a newly designed multi-IFU spectrograph for the 3.6m Devasthal telescope, capable of capturing 2,304 spectra across 370-740nm with high throughput and spectral resolution.

Contribution

This paper presents the optical and opto-mechanical design of DOTIFS, a multi-IFU spectrograph with eight identical units for the Devasthal telescope.

Findings

Spectrograph achieves 26% average throughput.

Design supports 2,304 spectra simultaneously.

Optics and components are under fabrication.

Abstract

Devasthal Optical Telescope Integral Field Spectrograph (DOTIFS) is a new multi-Integral Field Unit (IFU) instrument, planned to be mounted on the 3.6m Devasthal optical telescope in Nainital, India. It has eight identical, fiber-fed spectrographs to disperse light coming from 16 IFUs. The spectrographs produce 2,304 spectra over a 370-740nm wavelength range simultaneously with a spectral resolution of R=1200-2400. It is composed of all-refractive, all spherical optics designed to achieve on average 26.0% throughput from the telescope to the CCD with the help of high transmission spectrograph optics, volume phase holographic grating, and graded coated e2v 2K by 4K CCD. We present the optical and opto-mechanical design of the spectrograph as well as current development status. Optics and optomechanical components for the spectrographs are being fabricated.