A Tolerance Allocation Method for AOTF Spectrometers Integrating Spectral and Spatial Optical Errors

The Acousto-Optic Tunable Filter (AOTF) imaging spectrometer, as an advanced spectral imaging technology, has gained widespread global adoption due to its advantages including stare imaging capability, flexible band switching, and absence of moving components. However, during AOTF installation and alignment, shifts in the central wavelength of diffracted light can be induced by alignment errors, consequently reducing diffraction efficiency, while the imaging quality is simultaneously significantly impacted by such errors. In conventional design processes, tolerance allocation has typically been performed separately, where an empirical tolerance distribution scheme would be developed to independently verify whether alignment errors meet design requirements for both imaging and spectral performance. Such approaches often result in excessively stringent tolerances with correspondingly high manufacturing costs. Through the establishment of a comprehensive model and simulation of the AOTF imaging spectrometer, sensitivity analyses of various alignment errors were conducted across both spectral and spatial dimensions. High-sensitivity and low-sensitivity parameter were identified through this analysis, enabling the development of assembly tolerances that simultaneously satisfy both requirements. The proposed tolerance allocation scheme was validated by Monte Carlo simulations, with results demonstrating that optical design outcomes meet specified performance metrics in both spectral and spatial dimensions under the allocated tolerances. Compared with conventional tolerance allocation approaches, tolerance requirements were significantly relaxed while production costs were reduced by the proposed method. Ultimately, an integrated tolerance design methodology was developed that holistically considers both the AOTF device itself and its optical-mechanical system, effectively addressing the historical issue of redundancy in AOTF spectrometer system tolerance design.