Design and calibration verification of the diffraction rotational snapshot spectral camera on the Tianwen-2 mission

<p indent="0mm">In the Tianwen-2 exploration mission, a spectral camera based on the diffracted rotation is deployed to capture the overall morphology and spectral information of the detected target at the moment of encounter with asteroids and other celestial bodies. The camera utilizes a diffractive optical element to encode the phase of incident light, resulting in point spread functions (PSFs) of different wavelengths exhibiting a similar shape while the PSFs rotates as the wavelength changes. These wavelength-dependent PSFs, acting as spectral priors for the imaging system, facilitate the reconstruction of spectral data from encoded images. This paper focuses on the design of the refractive-diffractive hybrid optical system and the calibration of the imaging system. The calibrated PSFs show strong consistency with the theoretically designed PSFs, confirming the accuracy and effectiveness of the calibration process and image data preprocessing.