双谱段Offner光谱成像仪设计

Design of dualband Offner spectral imager

相比基于平面或凹面光栅的光谱成像仪,采用凸面光栅作为分光元件的Offner光谱成像仪具有数值孔径大、无谱线弯曲、色畸变小、结构紧凑和加工装调简单等诸多优点,在各个领域获得越来越多的应用。为了满足深空探测任务对载荷高度集成化、宽光谱响应范围、轻小型化等多方面严格要求,采用Offner结构设计了一种双谱段光谱成像仪,并巧妙地利用光栅分区分光,使系统在宽谱段内具有优良的像质,且体积小、结构简单,满足了设计要求。光学系统所有反射曲面均为球面,公差较松,有利于加工和装调。对凸面光栅进行了设计,并分析了其衍射效率,该设计可以有效扩大整个系统的动态范围。

Compared with spectral imager based on the flat or concave grating, the Offner spectral imagerwhich utilizes convex grating as the diffractive element has several advantages, such as large numericalaperture, no Smile, small spectral Keystone,compact volume, easy manufacturing and alignment, etc.Consequently, it＇s becoming widely applied in many fields. In order to meet the requirements of highlyintegrated, broad working spectrum and miniaturized payload for deep space exploration mission, in thisarticle, an Offner spectral imager with dualband was designed. At the same time, a neatly spectralsplitting method using different part of grating was implemented. The system which met the designrequirements had fine image quality, small volume and compact configuration. All reflective curves of theoptics were designed sphere, which had loose tolerance and were convenient for manufacturing andalignment. The convex grating was framed and its diffraction efficiency was analyzed. The result showsthat the dynamic range of the whole system can be enlarged effectively using the elaborate design.