Optical design of high resolution echelle spectrograph

The general theories behind echelle and its applications in astronomy are briefed, and the differences between echelle spectrograph and plane grating spectrograph are analyzed and compared. An optical design, which features the use of white pupil collimator system, R4 echelle with large blaze angle, and the fold and off-axial Schmidt camera without center obstruction, has been made for a high resolution echelle spectrograph (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) under development, a more powerful tool for astrophysical research using high-resolution spectroscopy in China.