AOTF后楔角对光谱图像像质的影响

Influence of the AOTF rear cut angle on spectral image quality

针对AOTF成像光谱仪的光谱图像退化程度难以定量化评价的问题,提出了包含后楔角影响的AOTF器件调制传递函数(MTF)定量计算方法。该方法通过建立AOTF的光谱-空间维响应模型获取AOTF器件的线扩散函数(LSF),然后通过线扩散函数傅里叶变换得到理论MTF。在验证实验中,截止频率内的MTF理论值与实测值相对偏差小于15%,可以为AOTF的像质评估提供理论依据。进而,通过该定量计算方法讨论不同AOTF后楔角对光谱图像像质的影响。通过仿真分析得出,AOTF的后楔角难以同时满足横向色差校正与图像退化抑制,需要根据实际应用对于空间分辨率以及横向色差的要求进行取舍。所以,针对AOTF不同后楔角进行光谱图像像质的定量分析对于评估AOTF光谱图像像质具有重要意义,为AOTF器件设计提供了理论依据。

Spectral image degradation is a common problem of acousto-optic tunable filter(AOTF) imaging spectrometers,and it is difficult to quantitatively predict.To quantitatively evaluate the image quality of spectral images,a modulation transfer function(MTF) calculation method including the influence of the AOTF rear cut angle is proposed.In this method,the line spread function(LSF) of the AOTF device is obtained by establishing the spectrum-space dimension response model of the AOTF,and then the theoretical MTF is obtained by Fourier transform of the line spread function.In the validation experiment,the deviation between the measured MTF value and the theory is less than 15% within the cut-off frequency.It is a theoretical basis for image quality evaluation of the AOTF.Furthermore,the influence of different AOTF rear cut angles on spectral image quality is discussed by this quantitative method.After simulation,it is concluded that the rear cut angle of the AOTF has difficulty meeting the requirements of lateral chromatic aberration and image sharpness at the same time.The cut angle needs to be selected according to the requirements of practical application.Therefore,it is significant to evaluate the image quality of AOTFs with different rear cut angles.The method is an important theoretical basis for AOTF device design.