A 4-m Asymmetric Czerny-Turner Grating Spectrograph

Abstract

The design and construction of a high resolution asymmetric Czerny-Turner grating vacuum spectrograph are described. The two spherical mirrors are of equal radii but not concentric; the grating can be translated sideways so that various configurations, calculated by ray tracing to give minimum aberrations for different angles, can be established. The focal length is 4 m, and simple tests suggest that resolving powers of at least 700,000 in the green are attainable over the whole of a 50-cm plate.