Astigmatism-reduced spherical concave grating holographically recorded by a cylindrical wave and a plane wave for Rowland circle mounting

摘要

We propose a new recording system that employs a cylindrical wave and a plane wave to holographically record astigmatism-reduced Rowland-circle spherical gratings. We find that the astigmatism of the grating can be sharply reduced, so that the spectral intensity is improved. Meanwhile, its defocus aberration and meridional coma remain zero throughout the working spectrum, meaning the spectral resolution is similar to that of a conventional grating recorded by symmetric dual plane waves. We designed and made one astigmatism-reduced grating and one conventional grating for an actual Rowland-circle spherical-grating spectrometer. Our experimental results showed that the spectral intensity of the astigmatism-reduced grating is about five times that of the conventional grating, while the resolution of the astigmatism-reduced grating is close to that of the conventional grating. (C) 2018 Optical Society of America