红外合成孔径衍射光学系统成像特性建模与分析

Modeling and analysis for imaging characteristics of infrared array-aperture diffractive optical system

基于衍射成像机理,建立红外合成孔径衍射光学系统调制传递函数(MTF)和信噪比(SNR)模型。随后,基于三维时域有限差分(FDTD)方法计算成像系统衍射效率,进而结合调制传递函数与信噪比表征系统成像特性。最后,分析了不同工作波长、视场和填充因子对主镜成像特性的影响。分析结果表明,红外合成孔径衍射光学系统的衍射效率、MTF和信噪比均具有空变、谱变特性,且随主镜填充因子的减小而降低。当填充因子为0.6时,与理想的全孔径系统相比,MTF积分面积降低45.42%,信噪比减小4.92 dB。该模型可用于分析红外合成孔径衍射光学系统成像质量,为成像系统的设计提供参考。

This paper establishes the modulation transfer function(MTF)and signal-to-noise ratio(SNR)charac⁃terization models of the infrared array-aperture diffractive optical system based on the diffraction imaging mecha⁃nism.Subsequently,the imaging system diffraction efficiency is calculated based on the three-dimensional Finite Difference Time Domain(FDTD)method and the imaging characteristics are represented by combining the MTF and SNR.Finally,the effects of different working wavelengths,field of views and filling factors of the primary lens imaging characteristics are analyzed.The analysis results show that the diffraction efficiency,the MTF and SNR of infrared array-aperture diffractive optical system all have spectral and spatial variation characteristics,which reduce with the decrease of the primary lens filling factor.When the filling factor is 0.6,the integral area of MTF decreases by 45.42%and the SNR decreases by 4.92 dB compared with the ideal full aperture system.The established model can be used to characterize the imaging quality of infrared array-aperture diffractive optical system and provide reference to the imaging system design.