[Study on the advanced Schwarzschild imaging spectrometer with high resolution in broadband]

The Schwarzschild optical structure was studied for the application of imaging spectrometer. The perfect astigmatism-corrected condition was obtained based on the analysis of the astigmatism of the Schwarzschild structure. The structure was advanced in the paper. The Schwarzschild imaging spectrum system is composed of two Schwarzschild structures, which are the collimating mirror-convex mirror and the convex mirror-focusing mirror. The calculation was given to present the parameters of the imaging spectrum system. An example of the imaging spectrum system in the waveband of 340-500 nm was designed and proved our design theory. The solution of the initial optimum structure was designed by our theory and simulated. A system with NA 1.25, of which the modulation transfer functions (MTF) of all fields of view are more than 0.58 in the waveband in the required Nyquist frequency (20 lp x mm(-1)), is presented in the paper. The form of the design structure can be changed as C-T system, Ebert-Fastie system and Offner system. The result also certificated that the optical system theory can be applied to the small scale imaging spectrometer with high resolution and spectral broadband.