Analytical design of three-spectral-resolution scanning imaging spectrometer based on concave grating with multiple groove densities

Abstract

Imaging spectrometers are generally designed with constant spectral resolution and do not have flexibility to achieve imaging different targets at respective spectral resolution. In addition, unnecessary increase in the data cube and transmission pressure result in an efficiency decrease in information gathering and processing. In this paper, a scanning imaging spectrometer with three spectral resolution (SISTR) is proposed. The concave grating with different groove densities is designed at the aperture stop. SISTR achieves the simultaneous acquisition of three sets of spectral images with the same spectral range but different spectral resolution. This paper studies the key issues of such broadband imaging spectrometers with different spectral resolution. Also evaluated are how groove densities of the concave grating affect the spectral overlap and the ways the diameters and decenters of three areas on the concave grating affect the uniformity of the energy distribution among three sets of spectral images. Accordingly, SISTR with three spectral resolution and high variation ratio is optimized. SISTR achieves a high numerical aperture of 0.33 and three spectral resolution of 0.31 nm, 0.64 nm, 1.40 nm in a wide spectral range of 400 to 800 nm. This paper provides a theoretical reference for further developments of imaging spectrometers with multiple resolution.