The multi-wave imaging spectrometer with high spectral resolution and
high energy utilization is an essential tool to characterize the solar atmosphere. A
novel method based on the aberrations correction and high grating efficiency is
proposed to avoid the aberration and increase the temporal resolution. It is applied to
design a dual band high spectral resolution imaging spectrometer based on New
Vacuum Solar Telescope, it can simultaneously observe Hα 0.6563 um and CaII
0.8542 um lines, separately, improving the telescope observation efficiency. The ray
tracing and optimization for the optical system are carried out with Zemax software.
The results demonstrate that the wavefront RMS is roughly 0.06λ at 0.6563 um, and
0.04λ at 0.8542 um, within 3 arcmins field of view; The grating efficiency are all
better than 70% in the range from 0.6 um to 1.1 um, which are equivalent to that of
the fast imaging spectrograph (43%) installed in the New solar telescope at Big Bear
Solar Observatory. The method is proved to be feasible, and can be used as a guidance
to spectrometer design.