宽谱段一体化AOTF成像光谱仪光学系统设计

Design of Optical System for Broadband and Integrated AOTF Imaging Spectrometer

声光可调谐滤波器(AOTF)成像光谱仪能够同时获取图像、光谱及偏振信息,已成功应用于航天、农业、林业、医学及食品安全等领域,具有较好的发展前景。光学系统是AOTF成像光谱仪获取信息的关键部件之一。为此,研究国内外常见的AOTF成像光谱仪光学系统,介绍AOTF的工作原理及光谱仪的总体设计方案,计算全系统的前置、准直及成像等子系统光学设计参数,完成共口径光学系统的仿真设计。前置光学系统采用自由曲面离轴三反结构,与准直系统的光曈匹配,准直及成像系统为光阑前置的离轴三反系统。仿真设计结果表明,在工作谱段为0.4~5.0μm、焦距为125 mm、F数5和视场角为5.3°的情况下,系统的MTF值分别在谱段0.4~1.0μm、1.0~3.0μm和3.0~5.0μm下均接近于衍射极限且大于0.57,畸变小于5%,成像质量良好。

Acousto-optic tunable filter(AOTF)imaging spectrometer can acquire image,spectrum and polarization information simultaneously.It has been successfully applied to the aerospace,agriculture,forestry,medicine,food safety,and other fields,thus having good development prospects.Optical system is one of the key parts in an AOTF imaging spectrometer to obtain information.Therefore,the optical systems of common AOTF imaging spectrometers are studied in this paper,and the working principle of AOTF and the general design scheme of the spectrometers are introduced.Furthermore,the optical design parameters of the whole system,such as the front,collimating and imaging sub-systems are calculated,and the common-aperture optical system is simulated.The front optical system has an off-axis three-mirror structure based on free-form surface,which matches with the aperture stop of the collimating system,and the collimating and imaging systems are off-axis three-mirror systems with front offset of the aperture stop.The simulation results show that the system has an MTF values close to the diffraction limit and greater than 0.57 at the bands of 0.4--1.0μm,1.0--3.0μm,and 3.0--5.0μm,a distortion less than 5%,and good imaging quality,in the case of the working band of 0.4--5.0μm,F number 5,field of view angle of 5.3°.