Optimization method of wide flat-field holographic concave grating eliminating both astigmatism and coma

摘要

A merit function of coma and optimization method for the wide flat-field holographic concave gratings is proposed. Both the astigmatism and coma of concave gratings over the entire spectral range are designed to be eliminated. The numerical simulation demonstrates that the aberration is significantly decreased by eliminating astigmatism only, and thus the resolving power can be improved 1.5-3 times. Combined with pixel size of linear array detector, the spectral resolution of the dispersion system can be greatly further improved. This kind of concave grating can not only be produced by holographic method but also by mechanical method, which provides convenience for production.