AOTF-transmission grating slitless spectrometer for stellar target observation

Acousto-optic tunable filters (AOTFs) have been widely applied in imaging spectrometers across various detection fields. However, sidelobe diffraction inherent to AOTFs can introduce spectral crosstalk, and single-AOTF configurations suffer from low sampling efficiency at high spectral resolution. Combining AOTFs with other dispersive elements often increases system size, while traditional slit-based designs limit throughput and degrade resolution. In this paper, a design scheme for a hyperspectral imaging spectrometer for observing stellar targets is presented, based on double diffraction in an AOTF-transmission grating. This configuration achieves high spectral resolution while suppressing sidelobe effects and compensating for image drift caused by crystal birefringence. The integrated design reduces system volume, and the slitless architecture enhances light collection efficiency. We analyze the theory of double diffraction and validate the designed optical system. The results show that this double-diffraction, slitless imaging spectrometer is well-designed, with the system's spectral resolution meeting the design expectations, surpassing 0.2 nm over 95% of the energy concentrated within the imaging pixels, and the PSF's FWHM at each wavelength meeting the requirements. This provides a compact solution for future point-source observations.