Multi-grating spectrograph and method of changing gratings

摘要

An improved multiple grating spectrograph is provided comprising a grating changer for mounting gratings, and rotatable about an axis substantially perpendicular to grating lines such that changing from one grating to another preserves the wavelength-selecting angle of incidence of electromagnetic radiation. The grating changer preferably includes a grating holder, and an actuator for moving the holder about the axis.