Optical design and tolerancing of a hyperspectral imaging spectrometer

A hyperspectral imaging spectrometer covering the wavelength range from 420 nm to 1000 nm is designed for the purpose of monitoring Earth’s environmental change. It has an entrance slit length of 24 μm, f/# of 3, smile and keystone distortion smaller than 20% of the pixel pitch and a spectral resolution of 6.5 nm. We design and review thirteen systems including one Offner system, two Schwarzschild systems and ten TMA systems for such specifications. Freeform surface and aspheric surface are used in some of the systems to achieve the required system parameters. With all system performance being summarized and evaluated, advantages and disadvantages of three different system types are compared. We down select two systems for further fine adjustments and tolerancing analysis. Final systems with superior performance and detailed tolerancing analysis are given at the end.