New monochromators of concave grating suitable for space telescopes

Abstract

Three types of new mono chromators based on the new mounting of concave grating by Singh Majumdar (SM) are described. These mono chromators are very compact and simple in operation, fulfilling the requirements of a mono chromator in a space telescope in the VUV region. It is found theoretically (by geo-metric optics theory of concave diffraction grating given by Beutler and modified by Namioka, and by a ray tracing procedure by drawing spot diagrams at different wavelengths) as well as experimentally in the laboratory by setting up the mono chromator and taking sample spectra photographically that the spectral im-ages have very little aberration as compared to other mono chromators in the VUV region. The improvement obtained is three times.