Moderate-Resolution Holographic Spectrograph

TL;DR

This paper introduces a novel moderate-resolution holographic spectrograph that uses a cascade of gratings to achieve broad wavelength coverage with high efficiency, suitable for astrophysical observations.

Contribution

The paper presents a new holographic spectrograph design that covers 430-680 nm with high efficiency and uniform spectral coverage using a cascade of three gratings.

Findings

Achieves spectral resolution of about 6000.

Covers 430-680 nm wavelength range without gaps.

Optical efficiency reaches up to 75%.

Abstract

We present a new scheme of a moderate-resolution spectrograph based on a cascade of serial holographic gratings each of which produces an individual spectrum with a resolution of about 6000 and a bandwidth of 80 nm. The gratings ensure centering of each part of the spectrum they produce so as to provide uniform coverage of the broadest possible wavelength interval. In this study we manage to simultaneously cover the 430-680 nm interval without gaps using three gratings. Efficiency of the spectrograph optical system itself from the entrance slit to the CCD detector is typically of about 60 % with a maximum of 75 %. We discuss the advantages and drawbacks of the new spectrograph scheme as well as the astrophysical tasks for which the instrument can be used.