Scene-based non-uniformity correction for high-throughput LWIR imaging spectrometer using optical defocus method

For spatial-modulation imaging spectrometers, the conventional non-uniformity correction method cannot efficiently reduce the pattern noise caused by stationary interference fringes on the imaging plane. In this study, we apply optical the defocus method to realize scene-based non-uniformity correction. By applying severe defocusing, the diffraction effects can be neglected, and the point spread function of the system is equivalent to the geometric projection at the exit pupil. When the light of each spot is within the field of view, it illuminates the entire detector, and the detector obtains uniform irradiance. We can implement a single-point calibration or single-plus-two calibration using the uniform irradiance.