We propose a novel flat-field imaging spectrograph that consists of two plane gratings, four spherical mirrors, and two plane mirrors. The imaging spectrograph is designed in such a manner that the. primary and the secondary principal points of the whole optical system for the horizontal direction coincide with those for the vertical direction. In a paraxial approximation, it is essentially aberration free because an entrance slit and an imaging detector are placed on the primary and the secondary principal planes, respectively. Spot diagrams obtained from ray-tracing procedure8 have indicated that the proposed spectrograph is superior to the conventional Czerny-Turner mounting. # 1997 Optical Society of America
展开▼
