Rapid testing method for spectral smile and keystone in the alignment of imaging spectrometers

The measurement of spectral smile and keystone is crucial for both the performance evaluation and spectral retrieval of hyperspectral imagers. However, traditional methods are often either complex in procedure or low in accuracy. To address this issue, this paper proposes the discrepancy function matching (DFM) method and the error-predicted squared weighted centroiding (EPSWC) method for fast and high-precision testing. Considering the influence of spectral non-uniformity, a spectral peak-based spectral response non-uniformity (SRNU) correction method is proposed for non-uniformity correction in the spectral dimension. Relevant experimental results show that the SRNU correction-based DFM and EPSWC methods maintain very simple measurement procedures while achieving significantly improved measurement accuracy compared with other approaches. On this basis, a positioning distance evaluation function (PDEF)-based method is proposed to solve the degeneracy problem caused by variations in the shape and width of the spectrometer response function. Relevant simulation results demonstrate that the proposed method can maintain high localization accuracy and width measurement accuracy under different response function shapes and widths. The method proposed in this paper is applicable to various types of response functions. The related research will help improve the accuracy of imaging spectrometer alignment and performance testing, and promote the development of hyperspectral observation technology.