Design and analysis of conical diffraction imaging spectrometer with high spectral resolution and wide spectral dispersion range

Abstract

Astigmatism and distortion aberrations of conventional Offner-type imaging spectrometer with an in-plane diffraction grating will increase dramatically as its spectral dispersion width so that such spectroscopic mounting is usually suitable for such situation that both slit length and spectrum width are medium and that the spectrum width is less than the slit length. To short slit and high dispersion, novel conical diffraction Offner mounting is more appropriate. Based on the operation principle of this kind mounting, a set of optimized designs, which the focal ratio is 4，the spectral region from 400nm to 900nm, the slit length from 0.5mm to 1mm, and the dispersion width from 9.8mm to 28mm are obtained under the same optical size. To evaluate the imaging quality of the designed and to get the relation between slit length and dispersion width, the merit function and spectral response function are considered. The results show that conical diffraction Offner imaging spectrometers can image well while the spectrum width is less than the slit length, but no more than its 20 times.